GSK has secured a broader-than-anticipated FDA approval for Ojjaara (momelotinib), its novel JAK1/JAK2 and activin A receptor type 1 (ACVR1) inhibitor, for the treatment of intermediate or high-risk myelofibrosis patients with anemia. The approval extends to both treatment-naïve and previously treated patients, marking a significant advancement in myelofibrosis care.
The regulatory decision follows a three-month delay due to FDA requests for additional information, but ultimately resulted in a more comprehensive label than initially expected. GSK had originally anticipated approval only for second-line use in patients previously treated with other JAK inhibitors.
Clinical Trial Results Support Broad Approval
The approval was supported by compelling data from the MOMENTUM trial, where Ojjaara demonstrated superior efficacy compared to danazol in reducing transfusion dependence. Key findings showed that 31% of Ojjaara-treated patients achieved transfusion independence at week 24, compared to 20% in the control group. Notably, 97% of initial responders maintained their response through week 48.
Additional support came from the SIMPLIFY-1 trial, which, despite not meeting overall success criteria, showed benefits in a subset of treatment-naïve patients with anemia.
Addressing an Unmet Medical Need
Current myelofibrosis treatments, including Novartis/Incyte's Jakafi (ruxolitinib), while effective for symptom relief and survival improvement, often exacerbate anemia - a common symptom that leads to treatment discontinuation in approximately 30% of cases.
Ojjaara distinguishes itself as the only approved therapy that simultaneously addresses three key manifestations of myelofibrosis: anemia, constitutional symptoms, and splenomegaly. This comprehensive approach could significantly impact treatment strategies for the roughly 50% of myelofibrosis patients who present with anemia.
Commercial Implications
The broader approval strengthens GSK's commercial position, building upon their $1.9 billion acquisition of Sierra Oncology. The company had previously projected potential sales exceeding $1 billion in just the second-line setting. With the expanded label, market potential could increase substantially, though still trailing behind Jakafi's projected 2023 sales of $2.4-2.8 billion.
Safety and Administration
Ojjaara is administered as a once-daily oral medication, offering a convenient dosing schedule for patients. The drug's ability to manage anemia without exacerbation represents a significant advantage over existing JAK inhibitors in the treatment landscape.
