Little more than a month after the U.S. FDA approved the first gene therapy for adults with hemophilia B, Uniqure NV’s Hemgenix, strong phase III data have come from Pfizer Inc. The Pfizer results show fidanacogene elaparvovec, a vector containing an AAV capsid and a high-activity human coagulation factor IX (FIX) gene for treating adult men with moderately severe to severe hemophilia B, hit the primary endpoint in the phase III Benegene-2 study. The one-time therapy is designed to allow those living with hemophilia B to be able to produce FIX instead of receiving regular, ongoing doses of exogenous FIX.