This clinical trial study uses a modified adeno-associated virus (AAV) to carry the human factor VIII gene to the liver. In the liver is where factor VIII protein is made. The study product, SPK-8011, is available only to participants in this research study. This product has not been approved yet for use in the general public. This will be the first hemophilia A gene transfer research study done in the United States. To learn more about the benefits and risks related to this study, please contact Dr. Lindsey George at (267) 425-0132.In order to participate in this study, you must be male, 18 years or older, have hemophilia A with FVIII activity levels less or equal to 2%, a history of bleeding that requires prophylaxis or on demand therapy, and no history of inhibitor to factor VIII. This study requires a number of visits over the course of 12 months. All costs related to participation in the study will either be covered or reimbursed by the Sponsor of the study, Spark Therapeutics, and participants will be compensated for their time.

Individuals with a certain type of beta thalassemia that is treated with regular transfusions, and who are 50 years old and younger, may be able to participate. A number of screening tests will be done to determine if subjects can participate. These include review of your past medical history, blood and urine tests, bone marrow aspirate/biopsy, bone age/ DEXA scan, heart ultrasound, electrocardiogram, magnetic resonance imaging (MRI) of the heart and liver, and liver biopsy. If eligible, blood stem cells will be collected by apheresis or by bone marrow harvest. These stem cells will then have a healthy beta globin gene inserted. You will then be hospitalized and chemotherapy will be given to empty out the bone marrow. The stem cells, with the inserted gene, will then be given back to you. You will be followed for side effects and to see if the inserted gene helps you make hemoglobin.