Trial Outcomes & Findings for A Study Evaluating Tolerability and Efficacy of Navitoclax Alone or in Combination With Ruxolitinib in Participants With Myelofibrosis (NCT NCT03222609)

NCT ID: NCT03222609

Last Updated: 2026-01-20

Results Overview

Reduction in spleen volume is measured by magnetic resonance imaging/computerized tomography (MRI/CT).

Recruitment status

COMPLETED

Study phase

PHASE2

Target enrollment

191 participants

Primary outcome timeframe

Baseline, Week 24

Results posted on

2026-01-20

Participant Flow

This trial was conducted at 57 sites in 13 countries./territories.

Participants enrolled in Cohort 1a must have received ruxolitinib therapy for at least 12 weeks and currently be on a stable dose of ≥10 mg twice daily of ruxolitinib. For Cohort 1b, participants must have received prior treatment with ruxolitinib. For Cohort 2, participants must have received prior treatment with a JAK-2 inhibitor. For Cohort 3, participants must not have received prior treatment with a JAK-2 inhibitor or BET inhibitor.

Participant milestones

Participant milestones
Measure	Navitoclax + Ruxolitinib (Cohort 1a) Participants must have received ruxolitinib for at least 12 weeks and on stable dose of ≥10 mg tablets orally twice daily (BID) for ≥8 weeks prior to the 1st dose of navitoclax. Navitoclax tablets are administered once daily (QD) at a starting dose of 50 mg. This was increased after approximately ≥7 days to next dose level if platelet count is ≥75 × 10\^9/L up to a maximum dose of navitoclax 300 mg QD. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 1b) Those receiving ruxolitinib at Screening must be on a stable dose ≥10 mg tablets orally twice daily (BID) for ≥ 4 weeks prior to 1st dose of navitoclax. Those not receiving ruxolitinib at Screening received 10 mg ruxolitinib BID starting on Day 1. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose was increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax (Cohort 2) Participants must have received prior treatment with a Janus Kinase 2 (JAK-2) inhibitor. Those with Baseline platelet count \>150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 200 mg. Those with a Baseline platelet count ≤150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 100 mg, which could be increased to 200 mg once daily after 7 days provided the platelet count is ≥75 × 10\^9/L. Navitoclax didn't exceed 200 mg QD for the first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 3) Prior treatment with a Janus Kinase 2 (JAK-2) or Bromodomain and Extra-Terminal motif (BET) proteins inhibitor was prohibited. Ruxolitinib tablets administered orally twice daily (BID) based on Baseline platelet count as per the local approved label. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).
Overall Study STARTED	34	91	34	32
Overall Study COMPLETED	0	0	0	0
Overall Study NOT COMPLETED	34	91	34	32

Reasons for withdrawal

Reasons for withdrawal
Measure	Navitoclax + Ruxolitinib (Cohort 1a) Participants must have received ruxolitinib for at least 12 weeks and on stable dose of ≥10 mg tablets orally twice daily (BID) for ≥8 weeks prior to the 1st dose of navitoclax. Navitoclax tablets are administered once daily (QD) at a starting dose of 50 mg. This was increased after approximately ≥7 days to next dose level if platelet count is ≥75 × 10\^9/L up to a maximum dose of navitoclax 300 mg QD. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 1b) Those receiving ruxolitinib at Screening must be on a stable dose ≥10 mg tablets orally twice daily (BID) for ≥ 4 weeks prior to 1st dose of navitoclax. Those not receiving ruxolitinib at Screening received 10 mg ruxolitinib BID starting on Day 1. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose was increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax (Cohort 2) Participants must have received prior treatment with a Janus Kinase 2 (JAK-2) inhibitor. Those with Baseline platelet count \>150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 200 mg. Those with a Baseline platelet count ≤150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 100 mg, which could be increased to 200 mg once daily after 7 days provided the platelet count is ≥75 × 10\^9/L. Navitoclax didn't exceed 200 mg QD for the first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 3) Prior treatment with a Janus Kinase 2 (JAK-2) or Bromodomain and Extra-Terminal motif (BET) proteins inhibitor was prohibited. Ruxolitinib tablets administered orally twice daily (BID) based on Baseline platelet count as per the local approved label. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).
Overall Study Withdrew consent	3	9	4	2
Overall Study Lost to Follow-up	2	2	1	0
Overall Study Death	20	38	18	10
Overall Study Other, not specified	9	42	11	20

Baseline Characteristics

A Study Evaluating Tolerability and Efficacy of Navitoclax Alone or in Combination With Ruxolitinib in Participants With Myelofibrosis

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Navitoclax + Ruxolitinib (Cohort 1a) n=34 Participants Participants must have received ruxolitinib for at least 12 weeks and on stable dose of ≥10 mg tablets orally twice daily (BID) for ≥8 weeks prior to the 1st dose of navitoclax. Navitoclax tablets are administered once daily (QD) at a starting dose of 50 mg. This was increased after approximately ≥7 days to next dose level if platelet count is ≥75 × 10\^9/L up to a maximum dose of navitoclax 300 mg QD. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 1b) n=91 Participants Those receiving ruxolitinib at Screening must be on a stable dose ≥10 mg tablets orally twice daily (BID) for ≥ 4 weeks prior to 1st dose of navitoclax. Those not receiving ruxolitinib at Screening received 10 mg ruxolitinib BID starting on Day 1. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose was increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax (Cohort 2) n=34 Participants Participants must have received prior treatment with a Janus Kinase 2 (JAK-2) inhibitor. Those with Baseline platelet count \>150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 200 mg. Those with a Baseline platelet count ≤150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 100 mg, which could be increased to 200 mg once daily after 7 days provided the platelet count is ≥75 × 10\^9/L. Navitoclax didn't exceed 200 mg QD for the first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 3) n=32 Participants Prior treatment with a Janus Kinase 2 (JAK-2) or Bromodomain and Extra-Terminal motif (BET) proteins inhibitor was prohibited. Ruxolitinib tablets administered orally twice daily (BID) based on Baseline platelet count as per the local approved label. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Total n=191 Participants Total of all reporting groups
Race (NIH/OMB) Black or African American	2 Participants n=37 Participants	0 Participants n=44 Participants	1 Participants n=40 Participants	2 Participants n=121 Participants	5 Participants n=84 Participants
Age, Continuous	67.4 years STANDARD_DEVIATION 10.38 • n=37 Participants	66.5 years STANDARD_DEVIATION 9.26 • n=44 Participants	69.0 years STANDARD_DEVIATION 6.56 • n=40 Participants	68.0 years STANDARD_DEVIATION 10.10 • n=121 Participants	67.4 years STANDARD_DEVIATION 9.18 • n=84 Participants
Sex: Female, Male Female	11 Participants n=37 Participants	34 Participants n=44 Participants	14 Participants n=40 Participants	12 Participants n=121 Participants	71 Participants n=84 Participants
Sex: Female, Male Male	23 Participants n=37 Participants	57 Participants n=44 Participants	20 Participants n=40 Participants	20 Participants n=121 Participants	120 Participants n=84 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	2 Participants n=37 Participants	7 Participants n=44 Participants	4 Participants n=40 Participants	6 Participants n=121 Participants	19 Participants n=84 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	32 Participants n=37 Participants	84 Participants n=44 Participants	30 Participants n=40 Participants	26 Participants n=121 Participants	172 Participants n=84 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	0 Participants n=37 Participants	0 Participants n=44 Participants	0 Participants n=40 Participants	0 Participants n=121 Participants	0 Participants n=84 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=37 Participants	0 Participants n=44 Participants	0 Participants n=40 Participants	0 Participants n=121 Participants	0 Participants n=84 Participants
Race (NIH/OMB) Asian	0 Participants n=37 Participants	15 Participants n=44 Participants	3 Participants n=40 Participants	0 Participants n=121 Participants	18 Participants n=84 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=37 Participants	0 Participants n=44 Participants	0 Participants n=40 Participants	0 Participants n=121 Participants	0 Participants n=84 Participants
Race (NIH/OMB) White	32 Participants n=37 Participants	76 Participants n=44 Participants	30 Participants n=40 Participants	29 Participants n=121 Participants	167 Participants n=84 Participants
Race (NIH/OMB) More than one race	0 Participants n=37 Participants	0 Participants n=44 Participants	0 Participants n=40 Participants	1 Participants n=121 Participants	1 Participants n=84 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=37 Participants	0 Participants n=44 Participants	0 Participants n=40 Participants	0 Participants n=121 Participants	0 Participants n=84 Participants

PRIMARY outcome

Timeframe: Baseline, Week 24

Population: Full Analysis Set (FAS): all participants who take at least one dose of navitoclax

Reduction in spleen volume is measured by magnetic resonance imaging/computerized tomography (MRI/CT).

Outcome measures

Outcome measures
Measure	Navitoclax + Ruxolitinib (Cohort 1a) n=34 Participants Participants must have received ruxolitinib for at least 12 weeks and on stable dose of ≥10 mg tablets orally twice daily (BID) for ≥8 weeks prior to the 1st dose of navitoclax. Navitoclax tablets are administered once daily (QD) at a starting dose of 50 mg. This was increased after approximately ≥7 days to next dose level if platelet count is ≥75 × 10\^9/L up to a maximum dose of navitoclax 300 mg QD. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 1b) n=91 Participants Those receiving ruxolitinib at Screening must be on a stable dose ≥10 mg tablets orally twice daily (BID) for ≥ 4 weeks prior to 1st dose of navitoclax. Those not receiving ruxolitinib at Screening received 10 mg ruxolitinib BID starting on Day 1. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose was increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax (Cohort 2) n=34 Participants Participants must have received prior treatment with a Janus Kinase 2 (JAK-2) inhibitor. Those with Baseline platelet count \>150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 200 mg. Those with a Baseline platelet count ≤150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 100 mg, which could be increased to 200 mg once daily after 7 days provided the platelet count is ≥75 × 10\^9/L. Navitoclax didn't exceed 200 mg QD for the first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 3) n=32 Participants Prior treatment with a Janus Kinase 2 (JAK-2) or Bromodomain and Extra-Terminal motif (BET) proteins inhibitor was prohibited. Ruxolitinib tablets administered orally twice daily (BID) based on Baseline platelet count as per the local approved label. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).
Percentage of Participants With ≥ 35% Reduction From Baseline in Spleen Volume at Week 24	26.47 percentage of participants Interval 12.88 to 44.36	21.98 percentage of participants Interval 13.97 to 31.88	11.76 percentage of participants Interval 3.3 to 27.45	62.50 percentage of participants Interval 43.69 to 78.9

SECONDARY outcome

Timeframe: Baseline, Week 24

Population: Full Analysis Set (FAS): all participants who take at least one dose of navitoclax

TSS is assessed by the Myelofibrosis Symptom Assessment Form (MFSAF) version 4.0. Participants complete a symptom diary and rate the following seven MF symptoms: fatigue, night sweats, abdominal discomfort, pruritus, pain under the ribs on the left side, early satiety, and bone pain daily using a scale from 0 (absent) to 10 (worst imaginable), and the scores are averaged over 7 days, with a minimum of 4 days required to calculate the average score. Participants for whom a valid average score cannot be calculated either at baseline or post-baseline are considered non-responders. The TSS reflects the sum of the scores of these symptoms, for a maximum possible score of 70 (i.e., most severe symptom experience).

Outcome measures

Outcome measures
Measure	Navitoclax + Ruxolitinib (Cohort 1a) n=34 Participants Participants must have received ruxolitinib for at least 12 weeks and on stable dose of ≥10 mg tablets orally twice daily (BID) for ≥8 weeks prior to the 1st dose of navitoclax. Navitoclax tablets are administered once daily (QD) at a starting dose of 50 mg. This was increased after approximately ≥7 days to next dose level if platelet count is ≥75 × 10\^9/L up to a maximum dose of navitoclax 300 mg QD. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 1b) n=91 Participants Those receiving ruxolitinib at Screening must be on a stable dose ≥10 mg tablets orally twice daily (BID) for ≥ 4 weeks prior to 1st dose of navitoclax. Those not receiving ruxolitinib at Screening received 10 mg ruxolitinib BID starting on Day 1. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose was increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax (Cohort 2) n=34 Participants Participants must have received prior treatment with a Janus Kinase 2 (JAK-2) inhibitor. Those with Baseline platelet count \>150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 200 mg. Those with a Baseline platelet count ≤150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 100 mg, which could be increased to 200 mg once daily after 7 days provided the platelet count is ≥75 × 10\^9/L. Navitoclax didn't exceed 200 mg QD for the first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 3) n=32 Participants Prior treatment with a Janus Kinase 2 (JAK-2) or Bromodomain and Extra-Terminal motif (BET) proteins inhibitor was prohibited. Ruxolitinib tablets administered orally twice daily (BID) based on Baseline platelet count as per the local approved label. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).
Percentage of Participants Achieving ≥ 50% Reduction From Baseline in Total System Score (TSS) at Week 24	20.59 percentage of participants Interval 8.7 to 37.9	25.27 percentage of participants Interval 16.75 to 35.47	8.82 percentage of participants Interval 1.86 to 23.68	34.38 percentage of participants Interval 18.57 to 53.19

SECONDARY outcome

Timeframe: Up to 254 weeks

Population: Full Analysis Set (FAS): all participants who take at least one dose of navitoclax; participants who were Baseline transfusion independent with baseline hemoglobin of ≥10 g/dL were excluded from the analysis since they were not evaluable for anemia response. Missing post-Baseline anemia response in Full Analysis Set applicable to evaluation of anemia response are considered as non-responders of anemia response.

For a participant who is transfusion independent (TI) at Baseline with hemoglobin value \< 10 g/dL, anemia response is achieved if the post-Baseline hemoglobin level increases by ≥2 g/dL without receiving packed red blood cells (PRBC) transfusion (for any reason) within 2 weeks and without any erythropoietin or mimetics within the last 4 weeks prior to the increase in hemoglobin level by ≥2g/dL was observed. Hemoglobin values more than 30 days after the last dose of study treatment or after the start of post-study treatment or disease progression, whichever is earlier, will not be considered in the analysis of anemia response. For a participant who is transfusion dependent (TD) at Baseline, anemia response is defined as a period of at least 12 consecutive weeks without PRBC transfusion at any time after the first dose of study drug and on or prior to 30 days post last dose of study drug, the start of post-study treatment, disease progression or death, whichever occurs earlier.

Outcome measures

Outcome measures
Measure	Navitoclax + Ruxolitinib (Cohort 1a) n=11 Participants Participants must have received ruxolitinib for at least 12 weeks and on stable dose of ≥10 mg tablets orally twice daily (BID) for ≥8 weeks prior to the 1st dose of navitoclax. Navitoclax tablets are administered once daily (QD) at a starting dose of 50 mg. This was increased after approximately ≥7 days to next dose level if platelet count is ≥75 × 10\^9/L up to a maximum dose of navitoclax 300 mg QD. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 1b) n=50 Participants Those receiving ruxolitinib at Screening must be on a stable dose ≥10 mg tablets orally twice daily (BID) for ≥ 4 weeks prior to 1st dose of navitoclax. Those not receiving ruxolitinib at Screening received 10 mg ruxolitinib BID starting on Day 1. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose was increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax (Cohort 2) n=25 Participants Participants must have received prior treatment with a Janus Kinase 2 (JAK-2) inhibitor. Those with Baseline platelet count \>150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 200 mg. Those with a Baseline platelet count ≤150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 100 mg, which could be increased to 200 mg once daily after 7 days provided the platelet count is ≥75 × 10\^9/L. Navitoclax didn't exceed 200 mg QD for the first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 3) n=15 Participants Prior treatment with a Janus Kinase 2 (JAK-2) or Bromodomain and Extra-Terminal motif (BET) proteins inhibitor was prohibited. Ruxolitinib tablets administered orally twice daily (BID) based on Baseline platelet count as per the local approved label. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).
Percentage of Participants Achieving Anemia Response Baseline transfusion independent with Baseline HGB <10 g/dL	28.57 percentage of participants Interval 3.67 to 70.96	23.68 percentage of participants Interval 11.44 to 40.24	52.94 percentage of participants Interval 27.81 to 77.02	38.46 percentage of participants Interval 13.86 to 68.42
Percentage of Participants Achieving Anemia Response Baseline transfusion dependent	50.00 percentage of participants Interval 6.76 to 93.24	16.67 percentage of participants Interval 2.09 to 48.41	37.50 percentage of participants Interval 8.52 to 75.51	100 percentage of participants Interval 15.81 to 100.0
Percentage of Participants Achieving Anemia Response Overall	36.36 percentage of participants Interval 10.93 to 69.21	22.00 percentage of participants Interval 11.53 to 35.96	48.00 percentage of participants Interval 27.8 to 68.69	46.67 percentage of participants Interval 21.27 to 73.41

SECONDARY outcome

Timeframe: Up to 254 weeks

Population: Full Analysis Set (FAS): all participants who take at least one dose of navitoclax; participants with missing bone marrow fibrosis grade (either Baseline or post-Baseline) or those with bone marrow fibrosis Grade 0 at Baseline were excluded from the analysis for the change in bone marrow fibrosis grade

Bone marrow grading is assessed according to the European Consensus Grading System. The 4-point grading scale ranges from MF-0, which corresponds to normal bone marrow, to MF-3, diffuse and dense increase in reticulin with extensive intersections with coarse bundles of collagen, often associated with significant osteosclerosis.

Outcome measures

Outcome measures
Measure	Navitoclax + Ruxolitinib (Cohort 1a) n=31 Participants Participants must have received ruxolitinib for at least 12 weeks and on stable dose of ≥10 mg tablets orally twice daily (BID) for ≥8 weeks prior to the 1st dose of navitoclax. Navitoclax tablets are administered once daily (QD) at a starting dose of 50 mg. This was increased after approximately ≥7 days to next dose level if platelet count is ≥75 × 10\^9/L up to a maximum dose of navitoclax 300 mg QD. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 1b) n=77 Participants Those receiving ruxolitinib at Screening must be on a stable dose ≥10 mg tablets orally twice daily (BID) for ≥ 4 weeks prior to 1st dose of navitoclax. Those not receiving ruxolitinib at Screening received 10 mg ruxolitinib BID starting on Day 1. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose was increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax (Cohort 2) n=22 Participants Participants must have received prior treatment with a Janus Kinase 2 (JAK-2) inhibitor. Those with Baseline platelet count \>150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 200 mg. Those with a Baseline platelet count ≤150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 100 mg, which could be increased to 200 mg once daily after 7 days provided the platelet count is ≥75 × 10\^9/L. Navitoclax didn't exceed 200 mg QD for the first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 3) n=27 Participants Prior treatment with a Janus Kinase 2 (JAK-2) or Bromodomain and Extra-Terminal motif (BET) proteins inhibitor was prohibited. Ruxolitinib tablets administered orally twice daily (BID) based on Baseline platelet count as per the local approved label. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).
Percentage of Participants With ≥ 1 Grade Reduction From Baseline in Fibrosis Grade At Any Time Week 24	23.08 percentage of participants Interval 8.97 to 43.65	24.07 percentage of participants Interval 13.49 to 37.64	40.00 percentage of participants Interval 16.34 to 67.71	30.43 percentage of participants Interval 13.21 to 52.92
Percentage of Participants With ≥ 1 Grade Reduction From Baseline in Fibrosis Grade At Any Time Anytime during the post-Baseline period	41.94 percentage of participants Interval 24.55 to 60.92	41.56 percentage of participants Interval 30.43 to 53.36	40.91 percentage of participants Interval 20.71 to 63.65	48.15 percentage of participants Interval 28.67 to 68.05

SECONDARY outcome

Timeframe: Up to 254 weeks

Population: Full Analysis Set (FAS): all participants who take at least one dose of navitoclax; participants with Baseline bone marrow fibrosis grade \>0 and post-Baseline bone marrow fibrosis grade are included in the analysis

Grade of bone marrow fibrosis was assessed by investigators according to the European Consensus Grading System. The 4-point grading scale ranges from MF-0, which corresponds to normal bone marrow, to MF-3, diffuse and dense increase in reticulin with extensive intersections with coarse bundles of collagen, often associated with significant osteosclerosis. The time to first achieving a reduction of at least 1 grade in bone marrow fibrosis from Baseline was summarized.

Outcome measures

Outcome measures
Measure	Navitoclax + Ruxolitinib (Cohort 1a) n=13 Participants Participants must have received ruxolitinib for at least 12 weeks and on stable dose of ≥10 mg tablets orally twice daily (BID) for ≥8 weeks prior to the 1st dose of navitoclax. Navitoclax tablets are administered once daily (QD) at a starting dose of 50 mg. This was increased after approximately ≥7 days to next dose level if platelet count is ≥75 × 10\^9/L up to a maximum dose of navitoclax 300 mg QD. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 1b) n=32 Participants Those receiving ruxolitinib at Screening must be on a stable dose ≥10 mg tablets orally twice daily (BID) for ≥ 4 weeks prior to 1st dose of navitoclax. Those not receiving ruxolitinib at Screening received 10 mg ruxolitinib BID starting on Day 1. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose was increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax (Cohort 2) n=9 Participants Participants must have received prior treatment with a Janus Kinase 2 (JAK-2) inhibitor. Those with Baseline platelet count \>150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 200 mg. Those with a Baseline platelet count ≤150 × 10\^9/L initiated navitoclax film-coated tablets orally once daily (QD) at the starting dose of 100 mg, which could be increased to 200 mg once daily after 7 days provided the platelet count is ≥75 × 10\^9/L. Navitoclax didn't exceed 200 mg QD for the first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of the Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).	Navitoclax + Ruxolitinib (Cohort 3) n=13 Participants Prior treatment with a Janus Kinase 2 (JAK-2) or Bromodomain and Extra-Terminal motif (BET) proteins inhibitor was prohibited. Ruxolitinib tablets administered orally twice daily (BID) based on Baseline platelet count as per the local approved label. Navitoclax tablets were administered orally once daily (QD) per Baseline platelet count (\>150 × 10\^9/L starting dose of 200 mg; ≤150 × 10\^9/L starting dose of 100 mg, which could be increased to 200 mg QD after 7 days provided platelet count is ≥75 × 10\^9/L). Navitoclax didn't exceed 200 mg QD for first 24 weeks of treatment. After Week 24 disease assessment, navitoclax dose may be increased to 300 mg QD at discretion of Investigator for those with suboptimal spleen response defined as failure to achieve spleen volume reduction of at least 10% per imaging. Participants continued their treatment until the end of clinical benefit, unacceptable toxicity, or they met other protocol criteria for discontinuation (whichever occurred first).
Time to First Reduction in Fibrosis Grade	24.1 weeks Interval 11.1 to 107.1	24.1 weeks Interval 9.3 to 97.1	12.4 weeks Interval 11.9 to 48.1	12.3 weeks Interval 7.0 to 96.1

Adverse Events

Navitoclax + Ruxolitinib (Cohort 1a)

Serious events: 21 serious events

Other events: 34 other events

Deaths: 20 deaths

Navitoclax + Ruxolitinib (Cohort 1b)

Serious events: 35 serious events

Other events: 91 other events

Deaths: 39 deaths

Navitoclax (Cohort 2)

Serious events: 18 serious events

Other events: 34 other events

Deaths: 18 deaths

Navitoclax + Ruxolitinib (Cohort 3)

Serious events: 12 serious events

Other events: 32 other events

Deaths: 10 deaths

Serious adverse events

Other adverse events

Additional Information

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Restriction type: OTHER