GSK plc announced that Japan's Ministry of Health, Labour and Welfare (MHLW) has approved Omjjara (momelotinib) for the treatment of myelofibrosis. Omjjara is a once-a-day, oral JAK1/JAK2 and activin A receptor type 1 (ACVR1) inhibitor. The approval is based on data from the pivotal phase III MOMENTUM and SIMPLIFY-1 trials.

This is the fourth major regulatory approval for GSK's momelotinib in the treatment of myelofibrosis, following approval under the brand name Ojjaara from the US Food and Drug Administration and authorisations under the brand name Omjjara from the European Commission and the Medicines and Healthcare products Regulatory Agency in the UK. Myelofibrosis is a blood cancer that affects approximately 1 in 500,000 people worldwide, with up to 5,000 patients impacted in Japan. In Japan, about 70% of patients diagnosed with primary myelofibrosis, and about half of those patients diagnosed with secondary myelofibrosis, have moderate to severe anaemia at the time of diagnosis.

Nearly all patients are estimated to develop anaemia over the course of the disease. Myelofibrosis patients with anaemia require additional supportive care, including transfusions, and more than 30% will discontinue treatment with established therapies due to anaemia. Patients who are anaemic and transfusion dependent have a poor prognosis and shortened survival.

The approval is based on data from the MOMENTUM and SIMPLIFY-1 pivotal phase III trials. MOMENTUM was designed to evaluate the safety and efficacy of momelotinib versus danazol for the treatment and reduction of key manifestations of myelofibrosis in an anaemic, symptomatic, JAK inhibitor-experienced population. SIMPLIFY-1 was designed to evaluate the efficacy and safety of momelotinib versus ruxolitinib in myelofibrosis patients who had not received a prior JAK inhibitor therapy.