An optogenetic gene therapy developed by Paris-based GenSight Biologics (Euronext: SIGHT) improved light sensitivity and aspects of visual function in patients with advanced retinitis pigmentosa, according to Phase I/II results published in the New England Journal of Medicine on October 7, 2026. Six of ten treated patients achieved clinically meaningful improvements in light sensitivity, while four of eight who completed behavioral testing improved in object detection or localization tasks.
The PIONEER trial evaluated GS030, which combines an intravitreal injection of an adeno-associated viral vector encoding the light-sensitive protein ChrimsonR with specialized goggles that convert visual scenes into pulses of amber light. The approach aims to restore limited visual perception by making surviving retinal ganglion cells responsive to light, bypassing photoreceptors damaged by the disease.
Seven of ten patients showed increased light sensitivity, with improvements ranging from twofold to more than 60-fold. Most ocular adverse events were mild or moderate, although one patient experienced transient central retinal artery occlusion immediately after injection, which resolved within minutes. The study primarily assessed safety, and the small sample size and exploratory nature of the visual assessments mean the efficacy findings require confirmation in larger trials.