Gene Therapy is the process that allows the transfer of genetic material (DNA or RNA) in order to prevent or cure a disease. Gene therapy is the transfer of a functioning gene that is mutated in the patient. Once integrated in the genome (the genetic heritage) of the patient, the functioning gene begins to restore the correct activity of the corresponding protein. Although the basic idea of gene therapy is simple, however, its practical realization is a real obstacle.
The first application of gene therapy in ophthalmology was performed for the treatment of Leber’s Congenital Amaurosis, a serious hereditary disease (related to the transmission of mitochondrial DNA), which leads to progressive loss of vision since the age of youth. The gene involved is called RPE65 and controls the production of an enzyme responsible for the recycling of retinol. The first results of this gene therapy were published in the New England Journal of Medicine (N Engl J Med 2008 22, 358: 2231-2239 and N Engl J Med 2008 22, 358: 2240-2248): the patients showed an improvement of the visual field and the sensitivity of the retina to light. There were no reported adverse effects.
Another important step in the development of gene therapy has been led by the company Avalanche Biotech for the treatment of age-related macular degeneration (AVA-101). The experiments conducted on animals (phase 2) have already shown that this technique is effective and safe. The study is currently on phase 2. Recently, a new gene therapy for the treatment of X-linked juvenile retinoschisis is going to be started using the AVA-311 product by Avalanche Biotech.