Hemophilia A Gene Therapy — Some Answers, More Questions

Hemophilia A is an X-linked disorder caused by the loss of coagulation factor VIII function. The phenotype of hemophilia A closely correlates with plasma factor VIII activity and is characterized by spontaneous or trauma-induced bleeding, classically hemarthrosis, that after repeated instances results in disabling hemophilic arthropathy. The current standard care is recurrent intravenous administration of factor VIII or subcutaneous delivery of a bispecific antibody, emicizumab, that mimics some of the functions of activated factor VIII. These therapies convert severe hemophilia A to moderate hemophilia A (characterized by infrequent, spontaneous bleeding) or mild hemophilia A (characterized by bleeding that is typically . . .