Second dose of gene therapy proves successful in patients with inherited blindness

Scientists from the Perelman School of Medicine at the University of Pennsylvania and The Children’s Hospital of Philadelphia led a study on congenital blindness that tested the effectiveness and safety of gene therapy in treating the condition. Three patients suffering from congenital blindness, each previously treated with gene therapy in one of their eyes, have shown improvement after their other eyes were also treated. All of the patients had better vision in dim light, and two could navigate through low-light. The results were also objectively tested through brain imaging. After both doses of inserted genes, none of the patients experienced immune reactions that canceled the benefits, as has occurred in tests for previous therapies. The success of a second dose was crucial. “Our concern was that the first treatment might cause a vaccine-like immune response that could prime the individual’s immune system to react against a repeat exposure,” Jean Bennett, a co-leader of the study, explains.