The US Food and Drug Administration (FDA) has approved an expanded indication for Hympavzi (marstacimab) to include treatment of patients with hemophilia A or B who are 12 years and older with inhibitors, as well as pediatric patients (ages 6 to 11 years) with or without inhibitors.
Hemophilia is a rare bleeding disorder that slows the blood clotting process. Serious complications can result from bleeding into the joints, muscles, brain, or other internal organs. The major types of this disorder are Hemophilia A and Hemophilia B. Although the two types have very similar signs and symptoms, they are caused by mutations in genes encoding for coagulation factor VIII or factor IX, respectively.
Marstacimab is designed to target tissue factor pathway inhibitors (TFPI), and thus inhibits TFPI’s natural attenuation of blood clot formation. By targeting the Kunitz 2 domain of TFPI, marstacimab may help re-establish hemostasis with the goal of offering a combination of bleed protection and straightforward administration.
The approval is largely based on results from the phase 3, global, open-label, multicenter BASIS trial (NCT03938792) evaluating the safety and efficacy of marstacimab in adolescent and adult participants ages 12 to 75 years of age with severe hemophilia A or moderately severe to severe hemophilia B with or without inhibitors. The results demonstrated the superiority of marstacimab in improving key bleeding outcomes, including significantly reducing mean treated annualized bleeding rate (ABR) by 93% compared to on-demand intravenous treatment with bypassing agents.
Additionally, interim results from the phase 3, global, open-label BASIS KIDS trial (NCT05611801) evaluating the safety and efficacy of marstacimab in children 1 to 17 years of age, supported the approval of marstacimab in children ages 6 to 17 years with hemophilia A or B with or without inhibitors. Results illustrated a mean treated ABR of 1.8 observed in patients who received marstacimab compared to a historical model-based mean ABR of treated bleeds of 3.6 in patients who received routine prophylaxis.
In children 6 to 17 years old with inhibitors, a mean treated ABR of 1.4 was observed in patients who received marstacimab compared to a historical model-based mean ABR of treated bleeds of 18.9 in patients who received OD therapy. Finally, in children 6 to 11 years old with inhibitors who were previously on on-demand therapy or without inhibitors who were previously receiving routine prophylaxis, respectively, a model-based mean treated ABR of 1.3 and 1.4 and a median ABR of 1.0 and 1.0 were observed.
The most common adverse reactions in adult and pediatric patients 6 years of age and older with or without inhibitors were injection site reaction, headache, pyrexia, arthralgia, diarrhea, pruritus, and rash. Thromboembolic events in two patients were observed among a total of 259 patients who received marstacimab in the open-label extension study. Thromboembolic events, hypersensitivity, embryofetal toxicity, and increased laboratory values of fibrin D-dimer and prothrombin fragment 1.2 are noted within the Warnings and Precautions section of the U.S. label.
For more information, click here.
To learn more about hemophilia and other rare hematology conditions, visit https://checkrare.com/diseases/hematologic-disorders/
