European Commission expands Pfizer's Hympavzi approval for hemophilia patients with inhibitors

The European Commission has granted marketing authorization to expand the approved indication for Hympavzi (marstacimab) to include patients 12 years of age and older weighing at least 35 kg with hemophilia A with FVIII inhibitors or hemophilia B with FIX inhibitors. This marketing authorization is valid in all 27 EU member states, as well as in Iceland, Liechtenstein, and Norway. Hympavzi is approved in the EU for people living with hemophilia A or B, with or without inhibitors.

Inhibitors limit treatment options for people living with hemophilia and are associated with an increased risk of uncontrolled bleeding. Of the more than 800,000 people in the world living with hemophilia A or hemophilia B, approximately 20% of those with hemophilia A and 3% of those with hemophilia B developed inhibitors to FVIII and FIX, respectively, and these therapies no longer prevent or stop bleeding episodes, particularly in individuals who are refractory to immune tolerance induction therapy.

This indication extension is based on results from the Phase 3 BASIS trial (NCT03938792) that evaluated the efficacy and safety of Hympavzi in adults and adolescents 12 years and older with severe hemophilia A or moderately severe to severe hemophilia B with inhibitors. In the active treatment period of the study, Hympavzi treatment resulted in a statistically significant and clinically meaningful 93% reduction in the mean treated annualized bleeding rate (ABR) (1.39 [95% CI: 0.85-2.29] vs. 19.78 [95% CI: 16.12-24.27]; p<0.0001), demonstrating superiority over on-demand therapy.

Superiority (p≤0.0001) of Hympavzi was also demonstrated across all measured bleeding-related secondary endpoints – spontaneous bleeds, joint bleeds, target joint bleeds, and total treated and untreated bleeds. In an interim analysis of the open-label extension trial, where patients were treated with Hympavzi for up to an additional 41 months, a total of 53 months of treatment, the mean (1.19 [95% CI: 0.72-1.95]) and median (0.00 [95% CI: 0.00-1.18]) treated ABRs remained low.

The safety profile for Hympavzi was consistent with Phase 1/2 results, and the most frequently reported adverse events in the study were injection site reactions, headache, pruritus, hypertension, and rash. The most serious adverse event reported from the clinical studies with Hympavzi was thrombosis.

Separately, the U.S. Food and Drug Administration accepted and granted Priority Review for the supplemental Biologics License Application for Hympavzi to expand its approved indication to include the treatment of hemophilia A or B patients 6 years and older with inhibitors, and pediatric patients ages 6 to 11 with hemophilia A or B without inhibitors. In the United States, Hympavzi is currently approved for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adult and pediatric patients 12 years of age and older with hemophilia A without factor VIII inhibitors or hemophilia B without factor IX inhibitors.