Pfizer's hemophilia therapy lowers bleeding in late-stage study

US drugmaker Pfizer Inc said this week late-stage study data for its experimental hemophilia therapy showed superiority to the current standard of care treatment in reducing bleeding rates in patients. The therapy, marstacimab, met its main trial goal, demonstrating superiority to factor replacement therapies, with a 92 per cent reduction in bleeding in patients with severe hemophilia A and moderately severe to severe hemophilia B, Pfizer said. Hemophilia hampers the body's ability to make blood-clotting proteins, leading to prolonged bleeding following injuries or surgery, and it primarily affects males, according to government data.

The estimated prevalence in the United States is 12 cases per 100,000 males for hemophilia A and 3.7 cases per 100,000 males for hemophilia B. The current standard of care requires regular infusion of the missing proteins. Pfizer's once weekly marstacimab is an anti-tissue factor pathway inhibitor that could help initiate blood clotting. Australian drugmaker CSL Ltd's gene therapy Hemgenix offers a long-term solution for hemophilia B patients, but is among the world's most expensive treatments. Pfizer is developing at least two other therapies for treating hemophilia.

Last year in December, the drugmaker met its main goal in a late-stage study for a hemophilia B gene therapy. The current trial of marstacimab only tested patients who did not have any antibodies that stop the production of the blood-clotting proteins called factor VIII or factor IX. Pfizer is also testing marstacimab in patients with those inhibitors, with data expected in late 2024.