India Pharma Outlook Team | Tuesday, 09 December 2025
Pfizer is drawing global attention today with new Phase 3 data showing its investigational therapy HYMPAVZI could shift treatment for people with hemophilia A or B who develop inhibitors.
These patients often face some of the toughest treatment hurdles, as inhibitors can block standard factor-replacement therapies.
The pivotal BASIS study—presented at the 67th American Society of Hematology Annual Meeting and published in Blood—found that HYMPAVZI cut annual bleeding rates by more than 90% compared with on-demand treatment. This marks one of the strongest signals yet for patients whose options have long been limited.
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Inhibitors, which neutralize FVIII or FIX therapies, affect about 20% of people with hemophilia A and 3% with hemophilia B globally. “The emergence of inhibitors poses significant treatment challenges and can increase disease burden for people living with hemophilia A or B,” said Davide Matino, BASIS Principal Investigator and Associate Professor of Medicine at McMaster University. He noted that the study showed once-weekly HYMPAVZI not only reduced bleeding episodes but also improved certain quality-of-life measures.
Safety data further support its potential. Among 51 participants in the safety group, no deaths or thromboembolic events occurred, and most side effects were mild or moderate. Only one treatment-related serious event led to discontinuation.
Michael Vincent, Chief Inflammation & Immunology Officer at Pfizer, said the findings underscore HYMPAVZI’s promise as a therapy that blends efficacy, safety, and simple administration. Pfizer has submitted the results to the FDA and the European Medicines Agency, aiming to expand access beyond the more than 40 countries where HYMPAVZI is already cleared for patients without inhibitors.
Unlike factor-replacement treatments, HYMPAVZI targets and blocks TFPI to help restore normal clotting, offering a streamlined weekly injection option that may redefine care for patients with inhibitors.
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