Marstacimab, an Anti-Tissue Factor Pathway Inhibitor, in Participants with Hemophilia Α or B, with and without Inhibitors: An Integrated Analysis of Safety

Background: Marstacimab (PF-06741086) targets tissue factor pathway inhibitor (TFPI) to restore hemostasis via the extrinsic pathway of blood coagulation. In phase 1/2 studies, long-term subcutaneous (SC) administration of marstacimab reduced bleeding episodes in adults with severe hemophilia A (HA) or hemophilia B (HB) (factor VIII or factor IX [FIX] ˂1%, respectively), with or without inhibitors. BASIS, the pivotal phase 3 study of marstacimab in adolescents and adults with severe HA (<1%) or moderately severe to severe (FIX ≤2%) HB, is ongoing. Given the potential risk for thrombotic and thromboembolic complications with novel non-factor-based agents, integrated safety analysis of studies of such agents are of interest. Wereport an integrated analysis of marstacimab safety in participants with HA or HB.