Pfizer Inc. announced that the European Commission has approved an expanded indication for HYMPAVZI, allowing its use in patients aged 12 years and older with hemophilia A or hemophilia B who have developed inhibitors to standard factor replacement therapies.
The approval covers adolescents and adults weighing at least 35 kilograms who have congenital factor VIII deficiency with FVIII inhibitors or congenital factor IX deficiency with FIX inhibitors. The decision expands treatment options for a particularly difficult-to-treat group of hemophilia patients who often face recurring bleeding episodes and limited therapeutic choices.
HYMPAVZI is administered as a once-weekly subcutaneous injection and does not require routine treatment-related laboratory monitoring. According to Pfizer, the therapy demonstrated superior bleed protection compared with on-demand treatment while maintaining a manageable safety profile.
Hemophilia is a rare inherited bleeding disorder caused by deficiencies in clotting factors. Patients with inhibitors develop antibodies that neutralize conventional factor replacement therapies, making standard treatment ineffective. Industry estimates indicate that approximately 20% of patients with hemophilia A and around 3% of patients with hemophilia B eventually develop inhibitors, leaving many vulnerable to uncontrolled bleeding and long-term complications such as joint damage.
Laurent Frenzel, Head of the Hemophilia Treatment and Research Center at Necker-Enfants malades Hospital in Paris, said inhibitors create major treatment challenges because they reduce the effectiveness of traditional therapies. He noted that HYMPAVZI offers patients in the European Union a once-weekly treatment option that has shown durable reductions in bleeding episodes during long-term follow-up studies.
The approval was supported by findings from the Phase 3 BASIS clinical trial, which evaluated the efficacy and safety of HYMPAVZI in adults and adolescents with severe hemophilia A or moderately severe to severe hemophilia B with inhibitors. During the active treatment phase, HYMPAVZI reduced the mean treated annualized bleeding rate by 93% compared with on-demand therapy. Researchers reported a treated annualized bleeding rate of 1.39 compared with 19.78 in the comparator group.
The therapy also demonstrated superiority across several secondary bleeding-related endpoints, including spontaneous bleeds, joint bleeds, target joint bleeds, and total treated and untreated bleeding episodes.
An interim analysis from the open-label extension study showed that bleeding control remained durable for up to 53 months of total treatment exposure. Investigators reported consistently low annualized bleeding rates during long-term follow-up.
Safety findings from the BASIS trial were consistent with earlier Phase 1 and 2 studies. The most commonly reported side effects included injection site reactions, headache, itching, hypertension, and rash. Thrombosis was identified as the most serious adverse event observed during clinical development.
Alexandre de Germay, Chief International Commercial Officer and Executive Vice President at Pfizer, said the approval addresses a critical unmet need for hemophilia patients living with inhibitors, whose treatment journeys are often complex and restrictive. He added that the authorization reflects Pfizer’s long-standing commitment to advancing hemophilia care globally.
The European Commission authorization is valid across all 27 European Union member states as well as Iceland, Liechtenstein, and Norway.
Separately, Pfizer said the U.S. Food and Drug Administration has accepted and granted Priority Review to a supplemental Biologics License Application seeking to further expand HYMPAVZI’s indication in the United States. The FDA is expected to make a decision during the second quarter of 2026.