NEW YORK, USA – June 8, 2026
Pfizer has secured U.S. Food and Drug Administration (FDA) approval for an expanded indication of HYMPAVZI® (marstacimab-hncq), significantly broadening access to its once-weekly subcutaneous treatment for people living with hemophilia A or hemophilia B. The latest approval extends HYMPAVZI’s use to include patients aged 12 years and older with inhibitors, as well as pediatric patients aged 6 to 11 years with or without inhibitors, marking an important advancement for individuals facing limited treatment options. Notably, HYMPAVZI becomes the first subcutaneous non-factor therapy approved for children aged 6 to 11 years with hemophilia B, addressing a major unmet need in pediatric bleeding disorder care. The regulatory milestone strengthens Pfizer’s leadership in hemophilia innovation and provides a simpler treatment approach that may help improve adherence, reduce bleeding episodes, and enhance quality of life for patients and caregivers worldwide.
FDA Approval Expands Access for Patients with Significant Unmet Needs
The FDA approval significantly broadens the treatment population eligible to receive HYMPAVZI, which is now indicated for routine prophylaxis to prevent or reduce bleeding episodes in adults and children six years of age and older with hemophilia A or hemophilia B, with or without inhibitors. Inhibitors remain one of the most challenging complications in hemophilia treatment, developing in approximately 20% of patients with hemophilia A and 3% of patients with hemophilia B. These inhibitory antibodies can render traditional factor replacement therapies ineffective, leaving patients vulnerable to uncontrolled bleeding and long-term complications.
The expanded indication offers an important new treatment option for these patients through a once-weekly subcutaneous injection that does not require routine treatment-related laboratory monitoring, potentially reducing treatment burden and improving disease management. Experts believe the availability of a simplified prophylactic option could transform care for both pediatric and adult populations living with complex forms of hemophilia.
Strong Phase 3 Data Demonstrate Significant Bleeding Reduction
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The approval was supported by results from the Phase 3 BASIS and BASIS KIDS clinical trials, which demonstrated substantial reductions in annualized bleeding rates (ABR). In patients aged 12 years and older with inhibitors, HYMPAVZI achieved a remarkable 93% reduction in treated annualized bleeding rate compared with on-demand intravenous bypassing therapy, highlighting its effectiveness in controlling bleeding episodes. Additional data from the BASIS KIDS trial demonstrated encouraging outcomes in children aged 6 to 17 years with or without inhibitors. Among pediatric patients receiving HYMPAVZI, mean treated annualized bleeding rates were substantially lower compared with historical treatment benchmarks, reinforcing the therapy’s potential to provide consistent bleed protection across multiple patient groups.
The strong efficacy profile was accompanied by a manageable safety profile consistent with previous studies, with the most commonly reported adverse events including injection-site reactions, headache, fever, joint pain, diarrhea, itching, and rash. These findings further strengthen confidence in HYMPAVZI as a meaningful advancement in hemophilia care.
A New Era for Hemophilia Treatment Innovation
HYMPAVZI represents a differentiated approach to hemophilia management through its novel mechanism of action targeting tissue factor pathway inhibitor (TFPI) rather than replacing missing clotting factors. By restoring balance between bleeding and coagulation, the therapy aims to provide durable bleed protection through convenient once-weekly administration. Since becoming the first anti-TFPI therapy approved in both the United States and Europe, HYMPAVZI has continued to gain regulatory momentum across global markets. The latest FDA approval reinforces Pfizer’s commitment to advancing care for rare bleeding disorders and highlights ongoing innovation in non-factor therapies.
With more than 800,000 people worldwide affected by hemophilia, and many patients continuing to face challenges associated with treatment burden, venous access, and inhibitor development, the expanded availability of HYMPAVZI could help reshape the standard of care. As healthcare providers increasingly seek effective and convenient prophylactic therapies, Pfizer’s latest achievement marks a significant step forward in improving outcomes for children and adults living with hemophilia.
Source: Pfizer press release
