Long-Term Safety and Effectiveness Study of Marstacimab Injection for Males with Severe Hemophilia A or Moderate to Severe Hemophilia B Aged 1 to 74 Years

What this Trial Is About

Researchers are evaluating the long-term safety, tolerability, and effectiveness of marstacimab as a preventive treatment in males aged 1 to 74 years with severe hemophilia A or moderately severe to severe hemophilia B, including those with or without inhibitors. This open-label extension study follows participants who completed prior Phase 3 studies without early termination, aiming to gather extended data on marstacimabs impact over several years. Participants receive marstacimab as a subcutaneous injection using a prefilled pen or syringe. Those aged 12 years and older start with a 300 mg loading dose followed by 150 mg weekly, with possible dose escalation to 300 mg weekly. Children aged 6 to under 12 years receive a 150 mg loading dose followed by 75 mg weekly, with the option to increase to 150 mg weekly. The study provides devices for administration and allows some flexibility based on participant needs and country-specific availability. During the study, participants undergo regular assessments including monitoring of adverse events, laboratory tests, coagulation factor consumption, bleeding rates, joint health, and quality of life questionnaires over a period of up to seven years. Researchers will track safety outcomes such as thrombotic events, injection site reactions, and immune responses to the drug. This extended follow-up helps understand marstacimabs long-term effects and supports dosing decisions in younger age groups.

Open-Label Extension Study of Marstacimab in Hemophilia Participants With or Without Inhibitors