A novel gene therapy for hemophilia A led to sustained expression of the clotting factor those patients lack, resulting in a reduction—or in some cases complete elimination—of painful and potentially life-threatening bleeding events, according to a new study led by researchers at Children’s Hospital of Philadelphia (CHOP). The results of the phase 1/2 trial, which were published today in the New England Journal of Medicine, are the first to demonstrate stable coagulation factor VIII in hemophilia A patients following gene therapy.