Hemophilia A affects 1 in 5000 to 10,000 males and roughly 60 percent have severe disease, with factor VIII activity less than 1 percent of normal. Hemophilia A is about four times as common as hemophilia B. The worldwide incidence of hemophilia is estimated at more than 400,000 people. Approximately 75% of patients with hemophilia worldwide receive inadequate treatment or have no access to treatment. Untreated or inadequate treated patients tend to have recurrent bleedings, which occurs spontaneously or post-traumatically in any organ or tissue. When recurrent and untreated, or inadequately treated, hemarthrosis results in permanent damage to articular cartilage, which may lead to deforming and crippling arthropathy even by the second decade of life. There is currently no cure for hemophilia. However, there are effective treatments available, but they may require lifelong infusion of FVIII which is manufactured from human plasma or by recombinant biotechnology.
Over the last two decades, studies on gene therapy for hemophilia have been performed and they are currently in Phase III of clinical development. Moving from protein replacement to gene replacement overcomes many of the unmet challenges to hemophilia care. Gene therapy can result in endogenous expression of the needed clotting factor leading to steady state levels and a sustained duration of action. This would liberate individuals from prophylaxis and the need for regular intravenous infusions. This would have the greatest impact on the overall burden of therapy and therapy compliance will no longer be an issue. Our gene therapy program attempts to make this ideal cure a reality.