Gene therapy for hemophilia: So close, yet so far away

After decades of research, a gene therapy for hemophilia appeared within reach last year. Steady progress in clinical testing had brought two promising treatments close to the finish line. One, for the most common form of the inherited blood disease, hemophilia A, was under regulatory review in the U.S. Another for the rarer hemophilia B form was close behind in the last leg of a late-stage study.