Pfizer’s Hympavzi gains EU approval for hard-to-treat hemophilia patients

Pfizer (NYSE:PFE) announced Wednesday that European regulators have cleared Hympavzi for adolescents and adults with hemophilia A or B with inhibitors, marking a significant expansion for the non-factor therapy in the 27 EU member states, Iceland, Liechtenstein, and Norway.

The approval addresses a critical complication in hemophilia care.

Approximately 20% of patients with hemophilia A and 3% with hemophilia B develop inhibitors—antibodies that neutralize traditional factor replacement therapies, rendering them ineffective.

These patients are often refractory to standard immune tolerance induction, leaving them vulnerable to chronic joint damage and life-threatening bleeds.

Clinical data from the Phase 3 BASIS trial supported the authorization, showing that Hympavzi reduced the mean annualized bleeding rate (ABR) by 93% compared to on-demand treatment.

In the study, the mean ABR dropped to 1.39 for patients on Hympavzi, down from 19.78 in the on-demand group.

Long-term interim data also suggested sustained efficacy, with bleeding rates remaining low for up to 53 months of treatment.

Unlike some traditional treatments, Hympavzi does not require routine laboratory monitoring.

While the safety profile remained consistent with earlier trials—with common side effects including headaches and injection site reactions—Pfizer noted that the most serious adverse event reported was thrombosis.

The regulatory momentum for Hympavzi continues in the U.S., where the FDA has granted Priority Review for a supplemental Biologics License Application.

This would potentially expand the drug's U.S. label to include children as young as six.

A PDUFA action date is expected in the second quarter of 2026.