The European Commission has approved Pfizer Inc.'s (NYSE: PFE) HYMPAVZI for treatment of patients 12 years and older with hemophilia A or B who have developed inhibitors to traditional factor replacement therapies.

The approval expands HYMPAVZI's indication to include patients weighing at least 35 kg with hemophilia A or B with inhibitors, a population that faces limited treatment options when standard factor replacement therapies become ineffective.

The decision was based on results from the Phase 3 BASIS trial, which showed HYMPAVZI reduced bleeding episodes by 93% compared to on-demand therapy. The study included 48 patients with hemophilia and inhibitors who received HYMPAVZI during a 12-month treatment period.

Inhibitors develop in approximately 20% of hemophilia A patients and 3% of hemophilia B patients, neutralizing factor replacement therapies and leaving patients vulnerable to uncontrolled bleeding episodes.

HYMPAVZI is administered as a once-weekly subcutaneous injection. The most frequently reported side effects in clinical trials included injection site reactions, headache, itching, high blood pressure, and rash. The most serious adverse event reported was thrombosis.

The marketing authorization is valid in all 27 EU member states, plus Iceland, Liechtenstein, and Norway. In the United States, Pfizer has submitted a supplemental application to the FDA to expand HYMPAVZI's indication to include patients 6 years and older with inhibitors, with an action date set for the second quarter of 2026.

HYMPAVZI has received regulatory approvals in more than 40 countries for eligible patients with hemophilia A or B without inhibitors, according to the company's press release statement.