Trial Outcomes & Findings for Exploratory Study of the Safety, Tolerability and Efficacy of Multiple Regimens of Natalizumab in Adult Participants With Relapsing Multiple Sclerosis (MS) (NCT NCT01405820)

NCT ID: NCT01405820

Last Updated: 2015-08-21

Results Overview

Cumulative number of combined unique active lesions (sum of the number of new gadolinium (Gd)-enhancing lesions and new or newly enlarging T2 hyperintense lesions not associated with Gd-enhancement on T1 weighted scans) based on brain magnetic resonance imaging (MRI) scans Up to Week 60.

• Recruitment status: COMPLETED
• Study phase: PHASE2
• Target enrollment: 290 participants
• Primary outcome timeframe: Up to Week 60
• Results posted on: 2015-08-21

Participant Flow

Four of the 6 arms in the Randomized Treatment Period (the 'every 12 weeks' arms) were closed prematurely. Participants who completed randomized treatment, met rescue criteria, or were impacted by arm closure (and met rescue criteria) were eligible to enroll in the open-label treatment period.

Participant milestones

Measure	Natalizumab 300 mg Intravenous (IV) Every 4 Weeks Natalizumab 300 mg IV every 4 weeks for 60 weeks. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Natalizumab 300 mg Subcutaneous (SC) Every 4 Weeks Natalizumab 300 mg SC every 4 weeks for 60 weeks. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Natalizumab 300 mg IV Every 12 Weeks Natalizumab 300 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Natalizumab 300 mg SC Every 12 Weeks Natalizumab 300 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Natalizumab 150 mg IV Every 12 Weeks Natalizumab 150 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Natalizumab 150 mg SC Every 12 Weeks Natalizumab 150 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.
Randomized Treatment Period STARTED	54	45	52	54	47	38
Randomized Treatment Period Safety Population	54	45	52	53	47	38
Randomized Treatment Period COMPLETED	43	35	9	3	2	1
Randomized Treatment Period NOT COMPLETED	11	10	43	51	45	37
Open-Label Treatment Period STARTED	44	35	42	42	42	32
Open-Label Treatment Period COMPLETED	40	33	39	37	40	30
Open-Label Treatment Period NOT COMPLETED	4	2	3	5	2	2

Reasons for withdrawal

Measure	Natalizumab 300 mg Intravenous (IV) Every 4 Weeks Natalizumab 300 mg IV every 4 weeks for 60 weeks. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Natalizumab 300 mg Subcutaneous (SC) Every 4 Weeks Natalizumab 300 mg SC every 4 weeks for 60 weeks. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Natalizumab 300 mg IV Every 12 Weeks Natalizumab 300 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Natalizumab 300 mg SC Every 12 Weeks Natalizumab 300 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Natalizumab 150 mg IV Every 12 Weeks Natalizumab 150 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Natalizumab 150 mg SC Every 12 Weeks Natalizumab 150 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.
Randomized Treatment Period Adverse Event	3	3	3	0	2	1
Randomized Treatment Period Withdrawal by Subject	6	2	2	2	0	0
Randomized Treatment Period Other	2	2	1	1	0	0
Randomized Treatment Period Physician Decision	0	2	1	0	0	0
Randomized Treatment Period Rescue	0	1	13	10	8	8
Randomized Treatment Period Incorrect Study Treatment	0	0	3	0	2	0
Randomized Treatment Period Treatment Arm Closed	0	0	20	36	33	28
Randomized Treatment Period Death	0	0	0	1	0	0
Randomized Treatment Period Withdrew Prior to Dosing	0	0	0	1	0	0
Open-Label Treatment Period Withdrawal by Subject	3	1	1	1	0	1
Open-Label Treatment Period Other	1	1	1	1	1	1
Open-Label Treatment Period Physician Decision	0	0	1	2	1	0
Open-Label Treatment Period Adverse Event	0	0	0	1	0	0

Baseline Characteristics

Exploratory Study of the Safety, Tolerability and Efficacy of Multiple Regimens of Natalizumab in Adult Participants With Relapsing Multiple Sclerosis (MS)

Baseline characteristics by cohort

Measure	Randomized Period: Natalizumab 300 mg IV Every 4 Weeks n=54 Participants Natalizumab 300 mg IV every 4 weeks for 60 weeks.	Randomized Period: Natalizumab 300 mg SC Every 4 Weeks n=45 Participants Natalizumab 300 mg SC every 4 weeks for 60 weeks.	Randomized Period: Natalizumab 300 mg IV Every 12 Weeks n=52 Participants Natalizumab 300 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 300 mg SC Every 12 Weeks n=54 Participants Natalizumab 300 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 150 mg IV Every 12 Weeks n=47 Participants Natalizumab 150 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 150 mg SC Every 12 Weeks n=38 Participants Natalizumab 150 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods.	Total n=290 Participants Total of all reporting groups
Age, Customized 20 to 29 years	7 participants n=5 Participants	11 participants n=7 Participants	7 participants n=5 Participants	7 participants n=4 Participants	5 participants n=21 Participants	11 participants n=10 Participants	48 participants n=115 Participants
Age, Customized 30 to 39 years	22 participants n=5 Participants	15 participants n=7 Participants	21 participants n=5 Participants	24 participants n=4 Participants	21 participants n=21 Participants	14 participants n=10 Participants	117 participants n=115 Participants
Age, Customized 40 to 49 years	20 participants n=5 Participants	16 participants n=7 Participants	17 participants n=5 Participants	17 participants n=4 Participants	16 participants n=21 Participants	9 participants n=10 Participants	95 participants n=115 Participants
Age, Customized 50 to 56 years	5 participants n=5 Participants	2 participants n=7 Participants	7 participants n=5 Participants	6 participants n=4 Participants	5 participants n=21 Participants	4 participants n=10 Participants	29 participants n=115 Participants
Age, Continuous	38.4 years STANDARD_DEVIATION 7.84 • n=5 Participants	36.3 years STANDARD_DEVIATION 8.92 • n=7 Participants	38.7 years STANDARD_DEVIATION 8.43 • n=5 Participants	38.7 years STANDARD_DEVIATION 7.85 • n=4 Participants	38.7 years STANDARD_DEVIATION 8.61 • n=21 Participants	36.0 years STANDARD_DEVIATION 9.03 • n=10 Participants	37.9 years STANDARD_DEVIATION 8.41 • n=115 Participants
Age, Customized 18 to 19 years	0 participants n=5 Participants	1 participants n=7 Participants	0 participants n=5 Participants	0 participants n=4 Participants	0 participants n=21 Participants	0 participants n=10 Participants	1 participants n=115 Participants
Sex: Female, Male Female	39 Participants n=5 Participants	29 Participants n=7 Participants	37 Participants n=5 Participants	41 Participants n=4 Participants	34 Participants n=21 Participants	24 Participants n=10 Participants	204 Participants n=115 Participants
Sex: Female, Male Male	15 Participants n=5 Participants	16 Participants n=7 Participants	15 Participants n=5 Participants	13 Participants n=4 Participants	13 Participants n=21 Participants	14 Participants n=10 Participants	86 Participants n=115 Participants

PRIMARY outcome

Timeframe: Up to Week 60

Population: Modified intent-to-treat (mITT) population: all randomized participants who received at least 1 dose of study drug, had at least 1 efficacy assessment, and had no statistical protocol deviations.

Cumulative number of combined unique active lesions (sum of the number of new gadolinium (Gd)-enhancing lesions and new or newly enlarging T2 hyperintense lesions not associated with Gd-enhancement on T1 weighted scans) based on brain magnetic resonance imaging (MRI) scans Up to Week 60.

Outcome measures

Measure	Randomized Period: Natalizumab 300 mg IV Every 4 Weeks n=52 Participants Natalizumab 300 mg IV every 4 weeks for 60 weeks.	Randomized Period: Natalizumab 300 mg SC Every 4 Weeks n=44 Participants Natalizumab 300 mg SC every 4 weeks for 60 weeks.	Randomized Period: Natalizumab 300 mg IV Every 12 Weeks n=45 Participants Natalizumab 300 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 300 mg SC Every 12 Weeks n=50 Participants Natalizumab 300 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 150 mg IV Every 12 Weeks n=35 Participants Natalizumab 150 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 150 mg SC Every 12 Weeks n=32 Participants Natalizumab 150 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods.
Cumulative Number of Combined Unique Active Lesions	0.23 lesions Standard Deviation 1.262	0.02 lesions Standard Deviation 0.151	3.84 lesions Standard Deviation 8.054	3.08 lesions Standard Deviation 8.216	6.09 lesions Standard Deviation 15.424	6.44 lesions Standard Deviation 11.285

Adverse Events

Randomized Period: Natalizumab 300 mg IV Every 4 Weeks

Serious events: 7 serious events

Other events: 40 other events

Deaths: 0 deaths

Randomized Period: Natalizumab 300 mg SC Every 4 Weeks

Serious events: 4 serious events

Other events: 31 other events

Deaths: 0 deaths

Randomized Period: Natalizumab 300 mg IV Every 12 Weeks

Serious events: 4 serious events

Other events: 31 other events

Deaths: 0 deaths

Randomized Period: Natalizumab 300 mg SC Every 12 Weeks

Serious events: 3 serious events

Other events: 34 other events

Deaths: 0 deaths

Randomized Period: Natalizumab 150 mg IV Every 12 Weeks

Serious events: 4 serious events

Other events: 31 other events

Deaths: 0 deaths

Randomized Period: Natalizumab 150 mg SC Every 12 Weeks

Serious events: 1 serious events

Other events: 17 other events

Deaths: 0 deaths

Open-label Period: Natalizumab 300 mg IV Every 4 Weeks

Serious events: 0 serious events

Other events: 2 other events

Deaths: 0 deaths

Open-label Period: Natalizumab 300 mg SC Every 4 Weeks

Serious events: 1 serious events

Other events: 4 other events

Deaths: 0 deaths

Open-label Period: Natalizumab 300 mg IV Every 12 Weeks

Serious events: 0 serious events

Other events: 2 other events

Deaths: 0 deaths

Open-label Period: Natalizumab 300 mg SC Every 12 Weeks

Serious events: 1 serious events

Other events: 0 other events

Deaths: 0 deaths

Open-label Period: Natalizumab 150 mg IV Every 12 Weeks

Serious events: 1 serious events

Other events: 4 other events

Deaths: 0 deaths

Open-label Period: Natalizumab 150 mg SC Every 12 Weeks

Serious events: 2 serious events

Other events: 6 other events

Deaths: 0 deaths

Serious adverse events

Measure	Randomized Period: Natalizumab 300 mg IV Every 4 Weeks n=54 participants at risk Natalizumab 300 mg IV every 4 weeks for 60 weeks.	Randomized Period: Natalizumab 300 mg SC Every 4 Weeks n=45 participants at risk Natalizumab 300 mg SC every 4 weeks for 60 weeks.	Randomized Period: Natalizumab 300 mg IV Every 12 Weeks n=52 participants at risk Natalizumab 300 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 300 mg SC Every 12 Weeks n=53 participants at risk Natalizumab 300 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 150 mg IV Every 12 Weeks n=47 participants at risk Natalizumab 150 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 150 mg SC Every 12 Weeks n=38 participants at risk Natalizumab 150 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods.	Open-label Period: Natalizumab 300 mg IV Every 4 Weeks n=44 participants at risk Natalizumab 300 mg IV every 4 weeks for 60 weeks. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Open-label Period: Natalizumab 300 mg SC Every 4 Weeks n=35 participants at risk Natalizumab 300 mg SC every 4 weeks for 60 weeks. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Open-label Period: Natalizumab 300 mg IV Every 12 Weeks n=42 participants at risk Natalizumab 300 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Open-label Period: Natalizumab 300 mg SC Every 12 Weeks n=42 participants at risk Natalizumab 300 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Open-label Period: Natalizumab 150 mg IV Every 12 Weeks n=42 participants at risk Natalizumab 150 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Open-label Period: Natalizumab 150 mg SC Every 12 Weeks n=32 participants at risk Natalizumab 150 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.
Infections and infestations Appendicitis	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Escherichia Urinary Tract Infection	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.1% 1/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Meningitis Enteroviral	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Progressive Multifocal Leukoencephalopathy	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Urosepsis	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Bronchitis	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.9% 1/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Neoplasms benign, malignant and unspecified (incl cysts and polyps) Carcinoma In Situ	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Neoplasms benign, malignant and unspecified (incl cysts and polyps) Lung Adenocarcinoma Metastatic	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Psychiatric disorders Bipolar I Disorder	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Psychiatric disorders Pathological Gambling	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Nervous system disorders Multiple Sclerosis Relapse	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	4.4% 2/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	4.3% 2/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.4% 1/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.4% 1/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.2% 2/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Nervous system disorders Epilepsy	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.1% 1/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Nervous system disorders Cerebrovascular Insufficiency	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Nervous system disorders Coma	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Nervous system disorders Polyneuropathy	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Gastrointestinal disorders Vomiting	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Gastrointestinal disorders Abdominal Pain	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.9% 1/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Musculoskeletal and connective tissue disorders Intervertebral Disc Protrusion	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Renal and urinary disorders Automatic Bladder	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Renal and urinary disorders Urinary Retention	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Investigations Nuclear Magnetic Resonance Imaging Abnormal	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Injury, poisoning and procedural complications Fall	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Injury, poisoning and procedural complications Radius Fracture	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.

Other adverse events

Measure	Randomized Period: Natalizumab 300 mg IV Every 4 Weeks n=54 participants at risk Natalizumab 300 mg IV every 4 weeks for 60 weeks.	Randomized Period: Natalizumab 300 mg SC Every 4 Weeks n=45 participants at risk Natalizumab 300 mg SC every 4 weeks for 60 weeks.	Randomized Period: Natalizumab 300 mg IV Every 12 Weeks n=52 participants at risk Natalizumab 300 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 300 mg SC Every 12 Weeks n=53 participants at risk Natalizumab 300 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 150 mg IV Every 12 Weeks n=47 participants at risk Natalizumab 150 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods.	Randomized Period: Natalizumab 150 mg SC Every 12 Weeks n=38 participants at risk Natalizumab 150 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods.	Open-label Period: Natalizumab 300 mg IV Every 4 Weeks n=44 participants at risk Natalizumab 300 mg IV every 4 weeks for 60 weeks. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Open-label Period: Natalizumab 300 mg SC Every 4 Weeks n=35 participants at risk Natalizumab 300 mg SC every 4 weeks for 60 weeks. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Open-label Period: Natalizumab 300 mg IV Every 12 Weeks n=42 participants at risk Natalizumab 300 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Open-label Period: Natalizumab 300 mg SC Every 12 Weeks n=42 participants at risk Natalizumab 300 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Open-label Period: Natalizumab 150 mg IV Every 12 Weeks n=42 participants at risk Natalizumab 150 mg IV every 12 weeks for 60 weeks with matching IV placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.	Open-label Period: Natalizumab 150 mg SC Every 12 Weeks n=32 participants at risk Natalizumab 150 mg SC every 12 weeks for 60 weeks with matching SC placebo administered during the intervening 4-week periods. Open-label natalizumab treatment 300 mg IV at Weeks 60, 64, and 68.
Infections and infestations Nasopharyngitis	24.1% 13/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	17.8% 8/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	15.4% 8/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	17.0% 9/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	17.0% 8/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	10.5% 4/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	4.5% 2/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.9% 1/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.4% 1/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.2% 2/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Urinary Tract Infection	14.8% 8/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	11.1% 5/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	5.8% 3/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	7.5% 4/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	8.5% 4/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Influenza	7.4% 4/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	4.4% 2/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	17.0% 8/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.9% 1/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.4% 1/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	9.4% 3/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Pharyngitis	5.6% 3/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	8.5% 4/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Bronchitis	3.7% 2/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.7% 3/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	7.5% 4/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	5.7% 2/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Gastroenteritis	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.7% 3/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Sinusitis	3.7% 2/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	5.8% 3/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	4.3% 2/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Infections and infestations Oral Herpes	7.4% 4/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.1% 1/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Psychiatric disorders Depression	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.7% 3/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Nervous system disorders Multiple Sclerosis Relapse	14.8% 8/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	13.3% 6/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	25.0% 13/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	32.1% 17/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	25.5% 12/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	13.2% 5/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.4% 1/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	7.1% 3/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.2% 2/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Nervous system disorders Headache	7.4% 4/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	20.0% 9/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	13.5% 7/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	9.4% 5/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.4% 3/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	10.5% 4/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Nervous system disorders Paraesthesia	3.7% 2/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	5.7% 3/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Nervous system disorders Sciatica	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	5.8% 3/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Vascular disorders Hypotension	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	5.8% 3/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Respiratory, thoracic and mediastinal disorders Oropharyngeal Pain	3.7% 2/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	7.5% 4/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Respiratory, thoracic and mediastinal disorders Cough	5.6% 3/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Gastrointestinal disorders Diarrhoea	7.4% 4/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	8.9% 4/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	8.5% 4/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Gastrointestinal disorders Nausea	5.6% 3/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	8.9% 4/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Gastrointestinal disorders Vomiting	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	8.9% 4/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.1% 1/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Gastrointestinal disorders Constipation	3.7% 2/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.4% 3/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Gastrointestinal disorders Abdominal Pain	1.9% 1/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	8.9% 4/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Gastrointestinal disorders Toothache	7.4% 4/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Musculoskeletal and connective tissue disorders Back Pain	5.6% 3/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	4.4% 2/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	5.8% 3/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	4.3% 2/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Musculoskeletal and connective tissue disorders Pain in Extremity	3.7% 2/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.7% 3/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	3.8% 2/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	4.3% 2/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Musculoskeletal and connective tissue disorders Arthralgia	5.6% 3/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	8.9% 4/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.4% 3/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
General disorders Fatigue	11.1% 6/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	13.3% 6/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	7.7% 4/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	4.3% 2/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
General disorders Injection Site Pain	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	5.7% 3/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	7.9% 3/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
General disorders Pyrexia	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.2% 1/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.4% 3/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	2.6% 1/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
General disorders Pain	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	6.7% 3/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.
Investigations Nuclear Magnetic Resonance Imaging Abnormal	0.00% 0/54 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/45 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/52 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	1.9% 1/53 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/47 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	5.3% 2/38 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/44 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/35 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/42 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.	0.00% 0/32 • AEs were analyzed during the randomized and open-label (OL) periods separately. Randomized period: AEs, after 1st randomized dose on Day 0 and prior to OL infusion of natalizumab at Week 60 (±5 days); SAEs also between Screening and dosing on Day 0. OL period: on or after OL infusion of natalizumab at Week 60 through to Week 72 (±2 weeks). If participant did not receive natalizumab infusions during the OL period (Week 60 to Week 72), all events with an onset date after Day 0 were considered as occurring during the randomized treatment period. AE data is presented for the Safety Population.

Additional Information

Biogen Study Medical Director

Biogen

Email: clinicaltrials@biogen.com

Results disclosure agreements

• Principal investigator is a sponsor employee Our agreement is subject to confidentiality but generally the PI can publish, for noncommercial purposes only, results and methods of the trial, but no other Sponsor Confidential Information. PI must give Sponsor no less than 60 days to review any manuscript for a proposed publication and must delay publication for up to an additional 90 days thereafter if Sponsor needs to file any patent application to protect any of Sponsor's intellectual property contained in the proposed publication.
• Publication restrictions are in place

Restriction type: OTHER