Australian-developed blood cancer treatment approved by FDA

The US FDA has approved GSK’s cancer drug Ojjaara (momelotinib) for the treatment of intermediate or high-risk myelofibrosis, including primary myelofibrosis or secondary myelofibrosis (post-polycythaemia vera and post-essential thrombocythaemia), in adults with anaemia. To date, it is the only approved medicine for both newly diagnosed and previously treated myelofibrosis patients with anaemia that addresses the key manifestations of the disease.

Myelofibrosis is a rare bone marrow blood cancer that can lead to severely low blood counts, including anaemia and thrombocytopaenia; constitutional symptoms such as fatigue, night sweats and bone pain; and splenomegaly (enlarged spleen). About 40% of patients have moderate to severe anaemia at the time of diagnosis, and nearly all patients are estimated to develop anaemia over the course of the disease. Myelofibrosis patients with anaemia often require transfusions and more than 30% will discontinue treatment due to anaemia. Patients who are transfusion dependent thus have a poor prognosis and shortened survival.

Ojjaara is an oral drug with a differentiated mechanism of action, featuring inhibitory ability along three key signalling pathways: Janus kinase (JAK) 1, JAK2 and activin A receptor, type I (ACVR1). Inhibition of JAK1 and JAK2 may improve constitutional symptoms and splenomegaly. Additionally, inhibition of ACVR1 leads to a decrease in circulating hepcidin, which is elevated in myelofibrosis and contributes to anaemia.

The FDA approval of momelotinib is supported by data from the pivotal MOMENTUM study and a subpopulation of adult patients with anaemia from the SIMPLIFY-1 phase III trial. 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. The trial met all its primary and key secondary endpoints, demonstrating statistically significant response with respect to constitutional symptoms, splenic response and transfusion independence. 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. Safety and efficacy results for SIMPLIFY-1 were based upon a subset of patients with anaemia.

“We are proud to add Ojjaara to our oncology portfolio and address a significant medical need in the community,” said Nina Mojas, Senior Vice President, Oncology Global Product Strategy at GSK. “We look forward to helping improve outcomes in this difficult-to-treat blood cancer.”

Momelotinib was originally invented at Cytopia, an Australian biotech founded in 1999 by Professor Andrew Wilks. The drug was the only asset of Sierra Oncology, which was ultimately acquired by GSK in 2022 for US$1.9 billion in an all-cash deal, making it the highest known acquisition amount paid for a drug invented in Australia.

According to Wilks, FDA approval for momelotinib is not only a personal victory but a triumph for the many scientists and clinicians with whom he worked across Australia. The molecule also has the potential to gain additional approvals for treating a number of inflammatory diseases, Wilks claims.

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