Injecting a gene therapy vector into one eye of someone suffering from LHON, the most common cause of mitochondrial blindness, significantly improves vision in both eyes, scientists have found.
During a phase 3 clinical trial, the international team from the University of Cambridge, University of Pittsburgh and Institut de La Vision Paris, successfully treated 37 patients suffering with ‘LHON’ (leber hereditary optic neuropathy).
The study (published in the journal Science Transitional Medicine) indicates that 78% of treated patients experienced significant visual improvement in both eyes, suggesting the improvement in the untreated eyes could be due to the transfer of ‘viral vector DNA’, from the eye which had been injected. This success marks hope that the treatment could help thousands of people across the world regain their sight.
The researchers used a technology called ‘mitochondrial targeting’ (developed by the Institut de la Vision in Paris) injecting a viral vector containing modified cDNA, in to the vitreous cavity of the eye of 37 different patients, who had suffered vision loss for between 6-12 months. The other eye received a placebo injection.
“We expected vision to improve in the eyes treated with the gene therapy vector only. Rather unexpectedly, both eyes improved for 78% of patients in the trial following the same trajectory over 2 years of follow-up.” said Dr Yu-Wai-Man, from Cambridge’s Department of Clinical Neuroscience.
Overall the treated eyes showed great improvement, with those still in the dynamic phase of the disease process showing an even greater improvement. The researchers found that the treated eyes were three times more likely to achieve vision better or equal than 20/200.
Dr Yu-Wai-Man said: “Saving sight with gene therapy is now a reality. The treatment has been shown to be safe and we are currently exploring the optimal therapeutic window.” Adding further Dr Sahel stated: “Other mitochondrial diseases could be treated using the same technology.”
The study was fully funded and sponsored by GenSight Biologics.