Pfizer announced that the European Commission granted a marketing authorization to expand the approved indication of Hympavzi (marstacimab) for the treatment of certain patients with hemophilia A or hemophilia B. The treatment is now indicated for patients with hemophilia A with FVIII inhibitors or hemophilia B with FIX inhibitors who are aged 12 or older and weigh at least 35 kg, according to a company press release issued on May 13th, 2026.
Patients with inhibitors to FVIII and FIX inhibitors are unable to continue taking factor replacement therapies, according to the release, as those therapies are neutralized by the inhibitors. Marstacimab is a once-weekly subcutaneous injection designed to offer the inhibitor patient population superior blood protection relative to on-demand (OD) treatments. The treatment has a unique mechanism of action relative to FVIII and FIX replacement treatments, wherein it targets the Kunitz 2 domain of tissue factor pathway inhibitor (TFPI), which inhibits the initiation of blood clotting. This is ultimately designed to help re-establish balance between bleeding and blood clot formation.
The indication extension is based on results from the Phase III BASIS trial, which evaluated marstacimab in adults and adolescents 12 years and older with severe hemophilia A or moderately severe to severe hemophilia B with inhibitors. The study found that treatment with marstacimab resulted in a statistically significant and clinically meaningful 93% reduction in the mean treated annualized bleeding rate and demonstrated superiority over OD therapy, according to the release.
“Inhibitors present a substantial challenge for people living with hemophilia as they neutralize traditional factor replacement therapies, in turn limiting treatment options and leaving patients vulnerable to uncontrolled bleeding episodes,” said Dr. Laurent Frenzel, Head of the Hemophilia Treatment and Research Center, Necker-Enfants Malades Hospital (Paris Cité), in the release. “The approval of [marstacimab] offers adults and adolescents in the EU a once-weekly subcutaneous option that has demonstrated the ability to reduce bleeding episodes and maintain bleed reduction based on observation to date in a long-term extension study.”
“For people living with hemophilia with inhibitors, recurring bleeding episodes can lead to damaged joints and introduce real limitations and disruptions to everyday life,” said Alexandre de Germay, Chief International Commercial Officer and Executive Vice President, Pfizer, in the release. “This approval brings a once-weekly medicine to the EU that meets a critical need for patients who face a treatment journey that can be complex and challenging with limited options available today, representing the latest step in Pfizer’s more than 40-year commitment to advancing care for people living with hemophilia. We look forward to working with regulators globally to continue bringing [marstacimab] to those who can benefit from it.”
