Marstacimab for People with Severe Hemophilia A or Moderate to Severe Hemophilia B Without Inhibitors: A Plain Language Summary of Publication of the BASIS Study.

What is this summary about? This is a summary of the results from a clinical study of treatment for people with severe hemophilia A or moderately severe to severe hemophilia B without inhibitors. Because severe hemophilia A and B predominantly affect men and boys, this study only included men and boys aged 12 to 74 years. The study was published in Blood. People with hemophilia either have low amounts of clotting factors or are missing certain clotting factors in their blood. There are medicines that people with hemophilia can take to replace the missing clotting factor. These medicines must be injected into a vein and are usually given more than once a week. Marstacimab is an antibody that works by attaching to a protein in the blood called tissue factor pathway inhibitor (or TFPI). TFPI works separately from clotting factors. Marstacimab helps the balance between blood flowing freely and clotting. Marstacimab is given by a simple injection under the skin (not in a vein or muscle) and can be taken less often than clotting factors. Marstacimab may offer a new way to help people with hemophilia. What were the results of the study? The study showed that men with hemophilia had fewer treated bleed events during 1 year with marstacimab treatment compared to previous factor replacement therapy. The researchers reported that marstacimab was safe and most side effects were mild to moderate. What do the results mean? These studies showed that marstacimab could help prevent bleeding in men with hemophilia A or B, without inhibitors.