FDA considers gene therapy that may cure one type of blindness

A new gene therapy treatment has proven effective at restoring vision for individuals suffering from a particular type of eye disease, and now the FDA is considering approving it. Should the treatment be approved, it will mark the first time gene therapy has been given the thumbs up to treat an inherited disease in the US...in this case, Leber congenital amaurosis, otherwise known as LCA.

LCA is caused by issues with the gene RPE65, which lacks the ability to make a necessary protein used by the retina. Someone with this disease will slowly lose their sight, often first being afflicted with very poor vision limited to just light and vague shapes, eventually leading to full blindness.

The gene therapy is called Voretigene neparvovec, and it involves sub-retinal injections for each eye. The patient must have a certain number of 'viable retinal cells' to undergo the patient, according to a document posted by the FDA. This procedure gives the patient a functional form of the RPE65 gene, which works to restore the vision cycle that would ordinarily happen in an healthy eye.

Though the treatment doesn't fully restore vision to normal, it was found to improve the patient's vision in a significant way, doing so for up to three years at a time. This is a breakthrough treatment, as thus far there haven't been any pharmacological treatments for the disease, leaving patients with simple visual aids to use until their vision decreases too much to be of use.

The majority of patients who underwent the gene therapy experienced only mild to moderate adverse effects which went away over time, including things like headache and nausea. The paper explains that a small number of individuals — many of whom had preexisting conditions — suffered more severe adverse effects. The treatment's benefits start appearing within a month of being administered.