Efficacy and safety of momelotinib in Janus kinase inhibitor-experienced Asian patients with myelofibrosis and anemia

Introduction: This post hoc analysis investigated the efficacy and safety of momelotinib in the Asian subpopulation of MOMENTUM (NCT04173494). Methods: Patients were randomized 2:1 to momelotinib 200 mg once daily (QD) plus danazol placebo (momelotinib group) or danazol 600 mg QD plus momelotinib placebo (danazol group) for 24 weeks (W), after which they could receive open-label momelotinib or danazol. Primary endpoint: W24 total symptom score (TSS) response rate (≥ 50% reduction from baseline). W24 key secondary endpoints: transfusion independence rate; mean TSS change from baseline; splenic response rate; rate of zero transfusions. Results: Seventeen Asian patients with myelofibrosis were included (momelotinib: n = 11; danazol: n = 6). TSS response rate at W24 was 36.4% with momelotinib and 0% with danazol. Secondary endpoints favored momelotinib and were consistent with the intention-to-treat population. Grade ≥ 3 treatment-emergent adverse events were reported in 36.4 and 66.7% of the momelotinib and danazol groups, respectively, including one grade ≥ 3 anemia in the momelotinib group. Treatment interruption and/or dose reduction occurred in 18.2 and 16.7% of the momelotinib and danazol groups, respectively. Two danazol-treated patients discontinued study treatment. Conclusion: In the Asian subpopulation of MOMENTUM, momelotinib improved myelofibrosis-associated symptoms, anemia measures, and spleen response, with generally favorable safety versus danazol.