Trial Outcomes & Findings for A Study to Assess the Long-term Safety and Efficacy of a Subcutaneous Formulation of Efgartigimod PH20 SC in Adults With Pemphigus (Vulgaris or Foliaceus) (NCT NCT04598477)

Last Updated: 2025-03-30

Results Overview

Incidence rates were calculated as 100 × n/PYFU. PYFU=participant-years of follow-up. The safety data sets includes participants with pemphigus vulgaris (PV) and pemphigus foliaceus (PF).

Recruitment status

TERMINATED

Study phase

PHASE3

Target enrollment

183 participants

Primary outcome timeframe

Up to 60 weeks

Results posted on

2025-03-30

Participant Flow

This study was terminated early based on the lack of observed efficacy in antecedent ARGX-113-1904. A total of 183 participants rolled over from ARGX-113-1904. Of these, 57 participants had a CRmin status (complete remission on minimal prednisone therapy) at rollover of which 34 participants did not receive efgartigimod PH20 SC in this ARGX-113-1905 study.

Two main analysis sets were analyzed in the outcome measures: Roll-over set includes all participants regardless of whether they received efgartigimod PH20 SC treatment during this study. Safety set includes participants who received at least 1 dose of efgartigimod PH20 SC during this study. Additional restrictions to the analysis set might apply in the different outcome measures. These are described in the analysis population descriptions.

Participant milestones

Participant milestones
Measure	Efgartigimod-efgartigimod PH20 SC Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Overall Study STARTED	123	60
Overall Study COMPLETED	64	23
Overall Study NOT COMPLETED	59	37

Reasons for withdrawal

Reasons for withdrawal
Measure	Efgartigimod-efgartigimod PH20 SC Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Overall Study Adverse Event	2	0
Overall Study Death	0	1
Overall Study Lost to Follow-up	1	0
Overall Study Physician Decision	7	2
Overall Study Pregnancy	0	1
Overall Study Requires Prohibited Medication	0	1
Overall Study Study Terminated by Sponsor	18	12
Overall Study Withdrawal by Subject	16	12
Overall Study Other	15	8

Baseline Characteristics

A Study to Assess the Long-term Safety and Efficacy of a Subcutaneous Formulation of Efgartigimod PH20 SC in Adults With Pemphigus (Vulgaris or Foliaceus)

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Efgartigimod-efgartigimod PH20 SC n=123 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=60 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.	Total n=183 Participants Total of all reporting groups
Age, Continuous	50.1 years STANDARD_DEVIATION 11.40 • n=93 Participants	52.4 years STANDARD_DEVIATION 13.02 • n=4 Participants	50.8 years STANDARD_DEVIATION 11.97 • n=27 Participants
Sex: Female, Male Female	61 Participants n=93 Participants	32 Participants n=4 Participants	93 Participants n=27 Participants
Sex: Female, Male Male	62 Participants n=93 Participants	28 Participants n=4 Participants	90 Participants n=27 Participants
Race/Ethnicity, Customized Asian	40 Participants n=93 Participants	9 Participants n=4 Participants	49 Participants n=27 Participants
Race/Ethnicity, Customized Black or African American	1 Participants n=93 Participants	2 Participants n=4 Participants	3 Participants n=27 Participants
Race/Ethnicity, Customized White	81 Participants n=93 Participants	47 Participants n=4 Participants	128 Participants n=27 Participants
Race/Ethnicity, Customized Other	1 Participants n=93 Participants	2 Participants n=4 Participants	3 Participants n=27 Participants
Race/Ethnicity, Customized Hispanic or Latino	3 Participants n=93 Participants	4 Participants n=4 Participants	7 Participants n=27 Participants
Race/Ethnicity, Customized Not Hispanic or Latino	120 Participants n=93 Participants	56 Participants n=4 Participants	176 Participants n=27 Participants

PRIMARY outcome

Timeframe: Up to 60 weeks

Population: Safety set

Incidence rates were calculated as 100 × n/PYFU. PYFU=participant-years of follow-up. The safety data sets includes participants with pemphigus vulgaris (PV) and pemphigus foliaceus (PF).

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=101 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=48 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Incidence of Treatment-Emergent Adverse Events (TEAE), Adverse Events of Special Interest (AESI), and Serious Adverse Events (SAE) Treatment-Emergent Adverse Event (TEAE)	116.4 number of events x 100/PYFU	113.0 number of events x 100/PYFU
Incidence of Treatment-Emergent Adverse Events (TEAE), Adverse Events of Special Interest (AESI), and Serious Adverse Events (SAE) Adverse Event of Special Interest (AESI)	72.0 number of events x 100/PYFU	69.3 number of events x 100/PYFU
Incidence of Treatment-Emergent Adverse Events (TEAE), Adverse Events of Special Interest (AESI), and Serious Adverse Events (SAE) Serious Adverse Event (SAE)	24.5 number of events x 100/PYFU	14.6 number of events x 100/PYFU

SECONDARY outcome

Timeframe: Up to 60 weeks

Population: Safety set

CRmin defined as the absence of new lesions and complete healing of established lesions while the participant was receiving prednisone at ≤10 mg/day for at least 8 weeks.

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=101 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=48 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Proportion of Participants With Pemphigus Vulgaris (PV) and Pemphigus Foliaceus (PF) Who Achieve CRmin	55 Participants	26 Participants

SECONDARY outcome

Timeframe: Up to 60 weeks

Population: Safety set - Participants with PV

CRmin (complete clinical remission on minimal prednisone therapy) defined as the absence of new lesions and complete healing of established lesions while the participant was receiving prednisone at ≤10 mg/day for at least 8 weeks.

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=86 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=41 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Proportion of Participants With Pemphigus Vulgaris (PV) Who Achieve CRmin	47 Participants	22 Participants

SECONDARY outcome

Timeframe: Up to 52 weeks

Population: Safety set - Participants with status DC at the roll-over visit were not included in the analysis.

Disease Control (DC) defined as absence of new lesions and the start of healing of established lesions

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=26 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=17 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Time to DC in Participants With PV and PF	8.5 days Interval 8.0 to 15.0	15.0 days Interval 8.0 to 22.0

SECONDARY outcome

Timeframe: Up to 52 weeks

Population: Safety set - Participants with status CR at the roll-over visit were not included in this analysis.

CR (Complete clinical remission) defined as the absence of new lesions and complete healing of established lesions

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=61 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=34 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Time to CR in Participants With PV and PF	66.0 Days Interval 43.0 to 182.0	71.0 Days Interval 41.0 to 100.0

SECONDARY outcome

Timeframe: Up to 52 weeks

Population: Safety set - Participants with status CRmin at the roll-over visit were not included in this analysis.

CRmin defined as the absence of new lesions and complete healing of established lesions while the participant was receiving prednisone at ≤10 mg/day for at least 8 weeks.

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=83 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=43 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Time to CRmin in Participants With PV and PF	229.0 days Interval 161.0 to The upper limit of 95% CI could not be reported because of insufficient number of participants with events.	169.0 days Interval 141.0 to 322.0

SECONDARY outcome

Timeframe: Up to 52 weeks

Population: Safety set - Participants with status CRoff at the roll-over visit were not included in this analysis.

Complete remission off therapy (CRoff) is defined as the absence of new and established lesions completely healed while the patient is receiving no prednisone therapy for at least 8 weeks.

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=83 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=43 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Time to CRoff in Participants With PV and PF	NA days The median survival time (95% CI) could not be calculated because the survival probability (95% CI) exceeded 50% at the longest time	NA days The median survival time (95% CI) could not be calculated because the survival probability (95% CI) exceeded 50% at the longest time

SECONDARY outcome

Timeframe: Up to 52 weeks

Population: Safety set - Only participants who achieved CRmin were considered for the analysis.

CRmin defined as defined as the absence of new lesions and complete healing of established lesions while the participant was receiving prednisone at ≤10 mg/day for at least 8 weeks.

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=42 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=23 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Time to Flare After CRmin in Participants With PV and PF	339.0 days Interval 223.0 to The upper limit of the 95% CI could not be reported because of insufficient number of participants with events.	168.0 days Interval 64.0 to The upper limit of 95% CI could not be reported because of insufficient number of participants with events.

SECONDARY outcome

Timeframe: Up to 52 weeks

Population: Safety set

The absence of DC with oral prednisone 1.5 mg/kg/day for a minimum of 3 weeks, or absence of DC due to prednisone-related SAE, or flare before CRmin resulting in withdrawal of the participant.

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=101 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=48 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Rate of Treatment Failure in Participants With PV and PF	3 Participants	1 Participants

SECONDARY outcome

Timeframe: Up to 60 weeks

Population: Roll-over set - Only participants who achieved DC were considered for the analysis.

A flare is defined as the appearance of 3 or more new lesions in a 4-week period that do not heal spontaneously within 1 week or the extension, of established lesions in a participant who had achieved DC.

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=122 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=59 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Number of Flares in Participants With PV and PF	0.8 Flares Standard Deviation 1.03	0.7 Flares Standard Deviation 0.79

SECONDARY outcome

Timeframe: Up to 60 weeks

Population: Roll-over set - For participants that do not achieve CRmin (or CRoff), NCPD until CRmin (or CRoff) is not calculated

Normalized Cumulative prednisone dose (NCPD, mg/kg/day) is the average daily intake of all weight-adjusted prednisone doses received during the study, taking into account the number of days in study

Outcome measures

Outcome measures
Measure	Efgartigimod-efgartigimod PH20 SC n=123 Participants Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=60 Participants Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Normalized Cumulative Prednisone Dose in Participants With PV and PF	0.212 mg/kg/day Standard Deviation 0.2018	0.241 mg/kg/day Standard Deviation 0.2401

Adverse Events

Efgartigimod-efgartigimod PH20 SC

Serious events: 16 serious events

Other events: 46 other events

Deaths: 0 deaths

Placebo-efgartigimod PH20 SC

Serious events: 4 serious events

Other events: 19 other events

Deaths: 1 deaths

Serious adverse events

Other adverse events

Additional Information

Regulatory Manager

Argenx

Phone: Please email:

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place

Measure	Efgartigimod-efgartigimod PH20 SC n=101 participants at risk Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=48 participants at risk Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Gastrointestinal disorders ANAL FISTULA	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Gastrointestinal disorders GASTRITIS EROSIVE	2.0% 2/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Gastrointestinal disorders INTESTINAL OBSTRUCTION	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Gastrointestinal disorders REFLUX GASTRITIS	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
General disorders DISEASE PROGRESSION	2.0% 2/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations ANAL ABSCESS	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations COVID-19	2.0% 2/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations EPIGLOTTITIS	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations LUNG ABSCESS	0.00% 0/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	2.1% 1/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations PNEUMONIA	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations SEPSIS	0.00% 0/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	2.1% 1/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations SEPTIC SHOCK	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations SKIN INFECTION	0.00% 0/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	2.1% 1/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Injury, poisoning and procedural complications PATELLA FRACTURE	0.00% 0/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	2.1% 1/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Injury, poisoning and procedural complications TIBIA FRACTURE	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Injury, poisoning and procedural complications WOUND	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Investigations BLOOD IMMUNOGLOBULIN G DECREASED	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Investigations BLOOD PRESSURE INCREASED	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Musculoskeletal and connective tissue disorders MUSCULOSKELETAL PAIN	0.00% 0/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	2.1% 1/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Musculoskeletal and connective tissue disorders OSTEONECROSIS	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Respiratory, thoracic and mediastinal disorders RESPIRATORY FAILURE	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Skin and subcutaneous tissue disorders PEMPHIGUS	3.0% 3/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	2.1% 1/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Vascular disorders DEEP VEIN THROMBOSIS	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Vascular disorders HYPERTENSION	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Vascular disorders SHOCK HAEMORRHAGIC	0.00% 0/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	2.1% 1/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.

Measure	Efgartigimod-efgartigimod PH20 SC n=101 participants at risk Participants who received efgartigimod PH20 SC in antecedent study ARGX-113-1904.	Placebo-efgartigimod PH20 SC n=48 participants at risk Participants who received placebo PH20 SC in antecedent study ARGX-113-1904.
Blood and lymphatic system disorders INCREASED TENDENCY TO BRUISE	0.00% 0/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	6.2% 3/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Cardiac disorders TACHYCARDIA	0.99% 1/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	6.2% 3/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
General disorders INJECTION SITE ERYTHEMA	4.0% 4/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	6.2% 3/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations COVID-19	11.9% 12/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	10.4% 5/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations FOLLICULITIS	5.0% 5/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	2.1% 1/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations NASOPHARYNGITIS	5.0% 5/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	2.1% 1/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations ORAL CANDIDIASIS	5.9% 6/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Infections and infestations URINARY TRACT INFECTION	5.0% 5/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	4.2% 2/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Investigations BLOOD LACTATE DEHYDROGENASE INCREASED	6.9% 7/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	2.1% 1/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Investigations BLOOD URIC ACID INCREASED	5.0% 5/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Investigations GLYCOSYLATED HAEMOGLOBIN INCREASED	5.9% 6/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Investigations LOW DENSITY LIPOPROTEIN INCREASED	5.0% 5/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Metabolism and nutrition disorders HYPERCHOLESTEROLAEMIA	5.0% 5/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	0.00% 0/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Musculoskeletal and connective tissue disorders MYOPATHY	2.0% 2/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	6.2% 3/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Nervous system disorders HEADACHE	3.0% 3/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	8.3% 4/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Renal and urinary disorders HAEMATURIA	2.0% 2/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	6.2% 3/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.
Skin and subcutaneous tissue disorders PRURITUS	2.0% 2/101 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.	6.2% 3/48 • Up to 60 weeks Participants who rolled over from the antecedent study ARGX-113-1904, and received at least 1 dose of efgartigimod PH20 SC during this ARGX-113-1905 study (Safety set). Laboratory abnormalities were reported as AEs.