MPN-483 Thrombocytopenic Myelofibrosis (MF) Patients Previously Treated With a JAK Inhibitor in a Phase 3 Randomized Study of Momelotinib (MMB) versus Danazol (DAN) [MOMENTUM]

MMB, an oral JAK1/2 and ACVR1/ALK2 inhibitor, was evaluated (vs DAN) in a pivotal phase 3 study of MF patients previously treated with a JAK inhibitor (JAKi). This subgroup analysis evaluated MOMENTUM patients with baseline platelet counts ≤150 × 10Eligibility: Primary or post-ET/PV MF; DIPSS high risk, Int-2, or Int-1; total symptom score (TSS) ≥10; hemoglobin10 g/dL; prior JAKi ≥90 days, or ≥28 days if RBC transfusions ≥4 units in 8 weeks or Grade 3/4 thrombocytopenia, anemia, or hematoma; palpable spleen ≥5 cm; platelets ≥25 × 10TSS response (≥50% reduction from baseline) rate at week 24. Secondary endpoints at week 24: transfusion independence (TI) rate, splenic response rate (SRR; ≥25% volume reduction from baseline), TSS change from baseline, SRR (≥35% reduction), and rate of zero transfusions since baseline.Mean baseline TSS: 29 MMB, 26 DAN, hemoglobin: 8.1 MMB, 7.8 DAN g/dL, and platelets: 74 × 10In symptomatic, anemic, and thrombocytopenic MF patients, MMB was superior to DAN for symptom responses, transfusion requirements, and spleen responses with comparable safety and favorable survival. MMB may address a critical unmet need in thrombocytopenic MF patients. NCT04173494.