Gene therapy shows gain in functional vision in continuation of phase 3 trial
Voretigene neparvovec demonstrated a gain in functional vision in patients with inherited retinal disease caused by the RPE65 gene, Spark Therapeutics announced in a press release.
The phase 3 trial included 20 patients who received voretigene neparvovec, formerly SPK-RPE65, in both eyes (intervention group) and a control group of nine patients. The primary endpoint of the randomized, controlled portion of the trial was change in bilateral mobility testing from baseline to 1 year. Spark previously announced a statistically and clinically significant improvement in bilateral mobility testing in treated patients compared with control patients.
After 1 year, all nine patients in the control group chose to cross over and receive voretigene neparvovec in both eyes. Eight of these patients then showed improvement in mobility testing at 1 year after administration. Mean improvement was 2.1 lux levels after 1 year in the crossover group and 1.9 lux levels after 2 years in the original intervention group, which was maintained from the first year.
Eight of nine crossover patients improved an average of almost 200-fold in full-field light sensitivity threshold testing after 1 year, compared with more than 100-fold in the original intervention group after 2 years, which was maintained from the first year.
Visual acuity improved an average of 4.5 letters in the crossover group and eight letters in the original intervention group.
No product candidate-related serious adverse events occurred. One eye experienced a serious adverse event that was related to the surgical procedure, not voretigene neparvovec.