Dose-Escalation Study Of A Self Complementary Adeno-Associated Viral Vector For Gene Transfer in Hemophilia B

Hemophilia B is caused by an absence or abnormality in the gene that produces the factor IX protein. Affected individuals cannot make a blood clot effectively and suffer from severe bleeding episodes. Repeated bleeding episodes, specifically into joints, can cause chronic joint disease and lead to disability. This research study will test the safety of giving an affected individual a normal factor IX gene which can produce factor IX protein in his body. We will give the normal gene for factor IX by using an inactivated (not able to function) virus called "the vector." The vector used in this study was developed from an adeno-associated virus that has been changed so that it is unable to cause a viral infection in humans. This inactivated virus was further altered to carry the factor IX gene and to locate within liver cells where factor IX protein is normally made. The protocol long-term follow-up (LTFU) period was changed from 15 years to 5 years in accordance with the FDA guidance for participants who received human gene therapy products. The FDA updated the guidance stating their current recommendations for the duration of an LTFU protocol, based on product, to be up to five years for AAV vectors. All study participants have completed 5 years of follow-up and are being transitioned off study.