FDA Approves Pfizer’s HYMPAVZI™ for Hemophilia A or B Treatment

Pfizer Inc. has announced that the U.S. Food and Drug Administration (FDA) has approved HYMPAVZI™ (marstacimab-hncq) as a new treatment option for hemophilia A or B. This groundbreaking therapy provides routine prophylaxis to prevent or reduce bleeding episodes in patients aged 12 and older who do not have inhibitors for factor VIII or IX. HYMPAVZI stands out as the first and only anti-tissue factor pathway inhibitor (anti-TFPI) approved in the U.S. for hemophilia and the first to be administered through a pre-filled, auto-injector pen.

The approval is based on results from the Phase 3 BASIS trial, which demonstrated that HYMPAVZI significantly reduced annualized bleeding rates (ABR) for patients compared to both routine prophylaxis (RP) and on-demand (OD) treatments. Specifically, it showed a 35% reduction in ABR against RP and a 92% reduction against OD treatments over a period of 12 months. The trial included 116 participants who were treated with HYMPAVZI, showcasing its effective bleed prevention capabilities with a once-weekly subcutaneous administration.

Dr. Suchitra S. Acharya, Director at Hemostasis and Thrombosis Center Northwell Health, commented on the significance of this approval, emphasizing that HYMPAVZI can alleviate the current treatment burden faced by patients who have had to endure frequent and time-consuming intravenous infusions. The new therapy offers a more manageable and less intrusive treatment regimen, potentially improving the quality of life for people with hemophilia A or B.

Hemophilia is a genetic disorder that affects the blood's ability to clot, leading to excessive bleeding. The condition is typically diagnosed in early childhood and impacts over 800,000 individuals globally. Continuous advancements in treatment have been made, but many patients still experience bleeding episodes and rely on frequent intravenous infusions, which can be demanding and disruptive to daily life.

Aamir Malik, Pfizer’s Chief U.S. Commercial Officer, expressed that HYMPAVZI marks a notable advancement in Pfizer’s long-term commitment to hemophilia care. This new treatment follows the recent approval of Pfizer’s other hemophilia therapies, expanding the company’s portfolio to now include anti-TFPI, gene therapy, and recombinant factor treatments, addressing a wide array of patient needs.

The BASIS trial's positive results were pivotal in securing FDA approval. The study also highlighted that HYMPAVZI was generally well-tolerated, with the most common side effects being injection site reactions, headache, and pruritus. The trial continues to evaluate the treatment in a cohort with inhibitors, with results anticipated by 2025. Additionally, Pfizer is conducting a separate BASIS KIDS study to assess the safety and efficacy of marstacimab in children aged 1 to 18.

For decades, hemophilia treatment primarily involved factor replacement therapies, which compensate for the missing clotting factors and help manage bleeding. Despite this, many patients face challenges with adherence due to the demanding nature of frequent infusions. Surveys indicate that time commitment is a significant barrier, especially for those on prophylactic regimens.

The approval of HYMPAVZI represents a significant step forward in hemophilia treatment, offering a more convenient and effective option for patients without inhibitors. This new therapy is set to reduce the frequency and severity of bleeding episodes, potentially transforming the standard of care for hemophilia A and B.