Gene therapy fail sees company stock price tumble

The trial involved 37 patients with Leber hereditary optic neuropathy (LHON), a rare mitochondrial disease that causes irreversible vision loss, who were injected with the gene therapy GS010 in one eye and a placebo in the other.The participants’ treated eyes showed significant improvent and patients were, on average, able to read 11 more letters on the ETDRS eye chart within 12 months.However, the untreated eyes showed an equally large improvent, and the surprising results spooked investors and shaved 34% off the company’s EuroNext share price in one day.{{quote-A:R-W:450-I:2-Q: This meaningful improvent of untreated eyes observed at week 48 was totally unexpected given what is known and has been published about the natural history of this devastating disease. -WHO:Bernard Gilly, CEO of GenSight}}Spontaneous recovery of sight is possible in LHON patients with the G11778 ND4 mutation, but it is only reported in up to 22% of cases – a much lower rate than that recorded in the trial.While the results represented a setback given the trial failed to reach its primary endpoint, GenSight CEO Mr Bernard Gilly said it did raise the possibility that a single injection could benefit both eyes.“This meaningful improvent of untreated eyes observed at week 48 was totally unexpected given what is known and has been published about the natural history of this devastating disease,” Gilly said.“We will continue to analyse the data to better understand our results, but they suggest that GS010 benefits both eyes in a way that is still to be understood.”The company is proceeding with two more Phase III trials and the patients will continue to be monitored for the next four years. One trial will focus on patients affected by LHON for less than six months, while the other will study the effect of injecting the formula in both eyes.At the time of publication, GenSight’s share price had slightly recovered to euro 3.01 (AU$4.80).