FDA approves JAK inhibitor Momelotinib for Myelofibrosis in Anemic adults

The US Food and Drug Administration (FDA) has approved momelotinib for the treatment of intermediate or high-risk myelofibrosis, including primary myelofibrosis or secondary myelofibrosis, in adults with anemia. It is a once-a-day, oral JAK1/JAK2 and activin A receptor type 1 (ACVR1) inhibitor. To date, it is the only approved medicine for both newly diagnosed and previously treated myelofibrosis patients with anemia that addresses the key manifestations of the disease, namely anemia, constitutional symptoms, and splenomegaly.

Myelofibrosis is a blood cancer associated with low blood counts, including anemia and thrombocytopenia. It often causes debilitating symptoms such as fatigue, night sweats, and bone pain, along with an enlarged spleen. Approximately 40% of patients have moderate to severe anemia at diagnosis, and almost all develop anemia during the disease's progression. Treating myelofibrosis patients with anemia has been challenging, often requiring transfusions. Sadly, more than 30% of these patients must discontinue treatment due to anemia. For those dependent on transfusions, prognosis and survival are grim.

The FDA approved momelotinib based on data from the MOMENTUM study and a subgroup of adult patients with anemia from the SIMPLIFY-1 trial. MOMENTUM aimed to assess momelotinib's safety and effectiveness compared to danazol for treating myelofibrosis symptoms in an anemic population who had previously used JAK inhibitors. This trial successfully met its primary and key secondary endpoints, showing significant improvements in constitutional symptoms, splenic response, and transfusion independence with momelotinib compared to danazol. SIMPLIFY-1, on the other hand, evaluated momelotinib against ruxolitinib in myelofibrosis patients who hadn't received prior JAK inhibitor therapy, focusing on a subset of patients with anemia.

Reference: GSK press release