Doctors have managed to halt the progression and even improve the vision of patients suffering from a genetic condition that causes them to go blind using a new gene therapy. Not only that, but the results have so far lasted at least four years, giving hope that there may yet be a cure for genetic-related blindness.
The use of gene therapy is by no means a novel treatment. Doctors have been working for decades to try and develop a similar remedy for the thousands of sufferers of cystic fibrosis, which is also caused by the action of a single faulty gene, yet these tests have been met with limited results which have not been permanent. This is why this latest experiment has been met with such excitement as it is one of few to tentatively indicate that the changes introduced into the patient’s eyes are potentially enduring.
“To permanently restore sight to people with inherited blindness would be a remarkable medical achievement,” explains Dr. Stephen Caddick, Director of Innovation at the Wellcome Trust, who part-funded the study. “This is the first time we've seen what appears to be a permanent change in vision after just one round of treatment. It's a real step forwards towards an era where gene therapy is part of routine care for these patients.”
The gene therapy has been used to treat people suffering from the genetic condition called choroideremia, which affects roughly 1 in every 50,000 people in the U.K. Caused by a faulty gene, the disease means that people who are unfortunate enough to have the mutation experience the slow loss of vision as the retinal photoreceptors in the eye are destroyed, eventually leading to many sufferers going completely blind. In the new study, six patients were given the latest treatment, with the results published in the New England Journal of Medicine.
The treatment works by injecting an engineered virus that contains the correct gene directly into the retina’s light-sensitive cells, the virus then splices the gene into the host cell’s DNA, with the new gene then compensating for the patient's faulty version. While the researchers thought that the treatment might simply halt the progression of blindness in the subjects, which is exactly what they saw in three of the patients, two others actually experienced significant improvements in vision. A sixth patient unfortunately experienced a decline in vision, after they had received a lower dose of the virus.
“The left eye is much improved to such an extent that I use it mostly to get about these days,” says Jonathan Wyatt, the first person in the world to be treated with the new therapy, which doubled the level of vision in his left eye. “It has substantially improved, it is fantastic. I feel very lucky, privileged and honored to be part of the fantastic John Radcliffe research group. I feel that even though I am the meat in a sandwich, my life will be making a contribution to help others.”