A new gene therapy treatment has restored some sight in a handful of blind patients suffering from Leber’s congenital amaurosis, a syndrome in which, because of a broken or missing gene called RPE65, retinal photoreceptor cells malfunction and eventually die. In separate studies at the University of Pennsylvania and University College London, researchers injected viral particles carrying a working copy of RPE65 into six patients’ retinas. The virus then ferried the replacement gene into retinal cells.
After treatment, two of the six patients were able to navigate a dimly lit maze. In the University of Pennsylvania trial, led by Jean Bennett, all three patients did better reading lines on an eye chart. “They would still have a hard time reading a book like War and Peace,” Bennett says, but “they can find their way around a room.” The results were published in May in The New England Journal of Medicine.
Most Leber’s sufferers have some vision as children but gradually grow completely blind by age 30. The adult subjects of these preliminary safety trials had already reached an advanced stage of the disease, which made the success of the treatment particularly promising, says Robin Ali, who led the University College London trial. “The fact that we had any efficacy in advanced degeneration is just hugely exciting,” he says. In the future, the therapy will target young patients to slow or halt the disease.