The purpose of this trial is to evaluate whether treatment with pelabresib in combination with ruxolitinib leads to improved clinical outcomes compared to ruxolitinib alone in patients with primary myelofibrosis (PMF), post-polycythemia vera myelofibrosis (PPV-MF), or post-essential thrombocythemia myelofibrosis (PET-MF) who have not previously received Janus kinase (JAK) inhibitor therapy.
Participants have diagnosis of primary myelofibrosis (PMF) or post-polycythemia vera myelofibrosis (post-PV MF) or post-essential thrombocythemia myelofibrosis (post-ET MF) according to the International Consensus Classification (ICC) of Myeloid Neoplasms and Acute Leukemias 2022
DIPSS risk category of intermediate-1, intermediate-2 or high-risk
Spleen volume ≥ 450 cm3 by CT or MRI scan (local read sufficient if no central read available)
Have an average TSS of ≥15 within 7 days prior to randomization, using MFSAF v. 4.0 (at least 4 out of 7 TSS assessments required for average calculation)
Prior splenectomy at any time or splenic irradiation in the previous 6 months
Prior hematopoietic cell transplant or participant anticipated to receive a hematopoietic cell transplant within 24 weeks from the date of randomization
Blasts ≥ 5% in bone marrow if results available at screening or history of accelerated phase (AP) or leukemic transformation
History of a malignancy (other than MF, PPV-MF or PET-MF) in the past 3 years in need of systemic treatment