Bone marrow fibrosis changes do not correlate with efficacy outcomes in myelofibrosis: Analysis of more than 300 JAK inhibitor-naïve patients treated with momelotinib or ruxolitinib

Using bone marrow fibrosis (BMF) biopsies collected from patients with myelofibrosis before and after 24 weeks of treatment with either momelotinib (MMB) or ruxolitinib (RUX), researchers found that 22% of those in the MMB arm experienced ≥ grade 1 improvement, compared with 23% of those in the RUX arm. According to these data from the double-blind, randomized, phase 3 SIMPLIFY-1 trial—presented during the 2022 American Society of Hematology Annual Meeting—85% of patients receiving MMB experienced stable or improved BMF, versus 81% for those receiving RUX. There was no association between BMF outcome and spleen or symptom outcomes noted for the MMB or RUX arms, and anemia improvement was not linked with BMF changes.