FDA Accepts NDA for GSK’s Myelofibrosis Drug

The FDA accepted GSK’s new drug application (NDA) for momelotinib, a potential new medicine that may address the significant unmet medical needs of patients with myelofibrosis who have anemia. The agency has assigned a Prescription Drug User Fee Act action date of June 16, 2023, GSK said in a statement.

Myelofibrosis is a cancer of the bone marrow and can lead to anemia. Momelotinib has the ability to inhibit three key signaling pathways: Janus kinase (JAK) 1, and JAK2 and activin A receptor, type I (ACVR1). Inhibition of JAK1 and JAK2 may improve symptoms and enlarged spleen, GSK said, and direct inhibition of ACVR1 leads to a decrease in circulating hepcidin, which is elevated in myelofibrosis and contributes to anemia.

Momelotinib was most recently developed by Sierra Oncology, which GSK acquired in July 2022. The NDA was submitted in June 2022 by Sierra.

The NDA is based on the results from key phase 3 trials, including the pivotal MOMENTUM trial, which met all primary and key secondary endpoints, including total symptom score, transfusion independence rate and splenic response rate.

MOMENTUM is a global, randomized, double-blind phase 3 clinical trial of momelotinib versus danazol (Danatrol, Danol, other brand names) in patients with myelofibrosis who were symptomatic and anemic and had been previously treated with an FDA-approved JAK inhibitor. After 24 weeks of treatment, patients on danazol were allowed to crossover to receive momelotinib. Early crossover to momelotinib was available for confirmed splenic progression.

The study demonstrated that momelotinib achieved statistically significant and clinically important efficacy across all prespecified and key secondary endpoints. Researchers found a trend toward improved overall survival in the momelotinib arm based on data up to week 24 and overall.

The rate of grade 3 or worse adverse events in the randomized treatment period was 54% in the momelotinib arm and 65% in the control arm. Serious treatment emergent adverse events were experience by 35% of patients in the momelotinib arm and 40% in the control arm. The most frequent non-hematologic adverse events were diarrhea, nausea, asthenia, pruritis and increased blood creatinine.

Momelotinib is not currently approved in any market.