FLICKR, HELGA BIRNA JÓNASDÓTTIR Patients with Leber’s congenital amaurosis (LCA), a genetic blindness disorder caused by a mutation in the retinal pigment epithelium 65 (RPE65) gene that encodes a rhodopsin-making enzyme, were the first to test the theory that gene therapy could restore sight. In 2007, surgeons injected a viral vector carrying an unmutated copy of RPE65 into one eye of each patient, many of whom experienced a heightened sensitivity to light within just a few days. But now, that improved vision is fading, suggesting that this original therapy may not lead to the permanent fix many were hoping for, trial researchers reported in two papers published this week (May 3) in The New England Journal of Medicine (NEJM).
The follow-up study to the trial conducted in the United States describes three LCA patients who received the gene therapy, each of whom showed improvement in visual sensitivity in the treated region. The improved sight peaked at one to three years following the treatment, then continued to decline, along with the concurrent loss of photoreceptors. “Our earlier results and these new measurements showed that photoreceptors continued to die at the same rate as they do in the natural course of the disease, regardless of treatment,” coauthor Samuel Jacobson of the Scheie Eye Institute at the University of Pennsylvania said in a statement.
The follow-up study of the trial, conducted in the United Kingdom, showed similar results: of the 12 LCA patients who received treatment, six ...
