The Food and Drug Administration (FDA) has extended the review period for momelotinib, an investigational drug developed by GSK for the treatment of myelofibrosis. The decision, initially expected by June 16, has been pushed back to September 16 to allow the agency to review newly submitted data from GSK. This delay introduces uncertainty into the potential market entry of a drug considered a key asset in GSK's recent acquisition strategy.
Momelotinib's Potential in Myelofibrosis Treatment
Momelotinib, the primary focus of GSK's nearly $2 billion acquisition of Sierra Oncology last year, is designed to address the symptoms of myelofibrosis, a bone marrow cancer that can lead to anemia, fatigue, and the need for frequent blood transfusions. While stem cell transplants offer a curative option for some patients, others rely on JAK inhibitors to manage the disease. Momelotinib's unique mechanism of action, targeting a different protein than existing JAK inhibitors, could provide a valuable alternative, particularly for patients who experience anemia as a result of other treatments.
Competitive Landscape and Clinical Advantages
Currently, three JAK inhibitors are approved for myelofibrosis: Incyte's Jakafi, Bristol Myers Squibb's Inrebic, and CTI BioPharma's Vonjo. However, Jakafi and Inrebic can exacerbate anemia in some patients. Momelotinib has demonstrated the ability to reduce anemia and decrease transfusion dependence in clinical trials, potentially offering a significant advantage over existing therapies. Despite these promising results, Jakafi remains a well-established treatment, and some analysts question whether momelotinib can gain significant market share.
Implications of the Delay
The FDA's decision to extend the review period has sparked speculation about the scope of momelotinib's potential approval. RBC Capital Markets analyst Brian Abrahams suggested that the additional data submitted by GSK might be intended to support a broader indication for the drug. While the delay was unexpected, given the availability of other JAK inhibitors and positive expert opinions, Abrahams anticipates eventual approval. However, he believes Jakafi will likely remain the preferred first-line treatment, regardless of the final label for momelotinib.
