
WFH and NBDF statement on severe adverse event with marstacimab rebalancing agent for hemophilia
The World Federation of Hemophilia (WFH) and National Bleeding Disorders Foundation (NBDF) have been informed by Pfizer of a severe adverse event that occurred December 14 in an individual on prophylaxis with marstacimab (Hympavzi®) who had suffered a fatal thrombotic stroke after minor surgery. The individual with hemophilia A and active inhibitors was a participant in Pfizer’s marstacimab clinical trial program who had been on marstacimab prophylaxis at the standard maintenance dose (150 mg once weekly) for three years. The thrombotic event occurred during the long-term open label extension (OLE) study. Pfizer is actively gathering information to better understand the causality of the event. Marstacimab is not currently approved by regulatory authorities for use in hemophilia with inhibitors and remains under clinical investigation.











