The FDA’s final action date this week is for GSK’s investigational drug, momelotinib, which the company is proposing to treat myelofibrosis patients with anemia. The decision is set to be released by June 16.
According to GSK, momelotinib works through a differentiated mechanism of action that involves the inhibition of three signaling pathways: the JAK1 and JAK2 cascades, as well as the activin receptor type I (ACVR1) pathway. By disrupting JAK1 and JAK2 signaling, momelotinib induces improvements in patient constitution and symptoms of splenomegaly. Meanwhile, its ACVR1 activity could decrease levels of hepcidin, which contribute to anemia in myelofibrosis.
Data from the pivotal Phase III MOMENTUM trial supported momelotinib’s FDA bid. In December 2022, GSK reported 48-week results from MOMENTUM at the 64th American Society of Hematology (ASH) Annual Meeting. Momelotinib achieved its primary efficacy endpoint of an at-least 50% reduction in Total Symptom Score after 24 weeks.
GSK’s myelofibrosis candidate also met key secondary endpoints including transfusion independence and splenic response rate, both likewise measured at 24 weeks.
MOMENTUM is a randomized and double-blinded clinical trial that randomized nearly 200 patients, at a 2:1 ratio, to receive either momelotinib or danazol, a common treatment used in myelofibrosis. At 24 weeks, patients on danazol were allowed to switch to momelotinib.

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