Pfizer has received FDA priority review for a supplemental biologics license application to expand the indication of Hympavzi (marstacimab).
The proposed label expansion would include patients with hemophilia A or B ages 6 and older with inhibitors and pediatric patients ages 6-11 without inhibitors, according to a Feb. 6 company news release. Hympavzi is currently approved in the U.S. to treat individuals ages 12 and older with hemophilia A or B without inhibitors.
If approved, Hympavzi would be the first non-factor prophylactic treatment for children ages 6-11 with hemophilia B. The FDA assigned a Prescription Drug User Fee Act action date in the second quarter of 2026.
Pfizer leaders said the treatment could become a transformative option for populations with limited or burdensome therapies.
The supplemental biologics license application is supported by data from Pfizer’s phase 3 BASIS and BASIS KIDS trials. The FDA previously granted Hympavzi Breakthrough Therapy Designation for routine prophylaxis in children ages 6 to younger than 12 with hemophilia B with or without inhibitors.
