Marstacimab

Marstacimab, sold under the brand name Hympavzi, is a monoclonal antibody medication used for the treatment of hemophilia A and hemophilia B. It is a tissue factor pathway inhibitor (TFPI) antagonist. It was developed by Pfizer. Marstacimab is a new type of medication that, rather than replacing a clotting factor, works by reducing the amount, and therefore, the activity of, the naturally occurring anticoagulation protein called tissue factor pathway inhibitor. This increases the amount of thrombin, an enzyme that is critical in blood clotting, that is generated. This is expected to reduce or prevent the frequency of bleeding episodes.

The most common side effects include injection site reactions, headache, and itching (pruritis).

Marstacimab was approved for medical use in the United States in October 2024, and in the European Union in November 2024. The US Food and Drug Administration (FDA) considers it to be a first-in-class medication.