Gene therapy brings vision back to the blind

Last month, three more patients treated with an experimental gene therapy reported improved vision. Add this to the first successful gene therapy for inherited blindness earlier this year and the science gets instant boost.

Despite years of work and resources devoted to it, experimental gene therapy had very little proven success in clinical trials. Some of the factors preventing it from effectively treating disease are the problem with viral vectors and the host’s reaction to the foreign object, in this case a virus. In 1999, a young patient participating in an experimental therapy for ornithine transcarboxylase deficiency (OTCD) died when his immune response rejected the virus. Four years later, a patient developed leukemia-like conditions.

This year’s clinical trials on the congenital blindness Leber congenital amaurosis (LCA) showed that gene therapy is safe and improved sight. The effects of the  new treatment lasted only for three months and are confined to the area of the eye where the new genes were inserted, so there is much work to be done.