Rebalancing the hemophilia teeter-totter

In this issue of Blood, Matino et al 1 demonstrate the safety and efficacy of the anti-tissue factor pathway inhibitor (TFPI) rebalancing agent marstacimab in severe hemophilia A (HA; 1%) or moderate-severe hemophilia B (HB; 2%) without inhibitory antibodies.Marstacimab joins concizumab as a US Food and Drug Administration (FDA)-approved monoclonal antibody agent directed against TFPI; both demonstrate superiority of anti-TFPI vs on-demand (OD) therapy in preventing bleeding and more patient-friendly subcutaneous (SC) administration.