Optogenetics, a technique that allows the control of nerve cell activity using light, was honored with the 2026 Nobel Prize in Medicine, awarded on October 5th to Karl Deisseroth, Peter Hegemann, and Georg Nagel. This major breakthrough in neuroscience opens significant therapeutic avenues, particularly for combating blindness.
Research teams, including those from the Institut de la Vision (Sorbonne Université/Inserm/CNRS) and the 15-20 rare disease center, had already achieved a world first in 2021, enabling a blind patient to partially regain some visual capabilities. Results from a more recent study, published on October 8th in the New England Journal of Medicine, confirm the potential of this approach in ten patients with retinitis pigmentosa.
Retinitis pigmentosa, affecting approximately one in 4,000 people worldwide, is an inherited retinal disease leading to the progressive degeneration of photoreceptor cells, which are essential for vision. In the absence of a cure, researchers have been exploring for over twenty years the idea of making other retinal cells light-sensitive.
Optogenetics, at the intersection of genetics and neuroscience, involves introducing a gene that produces a light-sensitive protein into nerve cells. These cells can then be activated by targeted light stimulation, independent of the specific genetic mutation causing the disease, thus offering potential benefits for various forms of retinitis pigmentosa.
The experimental treatment GS030, developed by GenSight Biologics, combines gene therapy with light-stimulating glasses. The gene therapy introduces a gene encoding the light-sensitive protein ChrimsonR into retinal ganglion cells, making them responsive to light. The glasses, equipped with a camera, capture images and project them onto the retina as light pulses to activate these cells.
The international PIONEER clinical trial, conducted on ten patients with advanced retinitis pigmentosa, aimed to assess the safety and tolerability of GS030. Although nine participants experienced ocular adverse events, mostly mild, none were deemed related to the treatment. Exploratory evaluations showed a clinically relevant improvement in light sensitivity in six patients.
Furthermore, four out of eight patients who underwent behavioral tests showed improved visual performance with the light-stimulating glasses, particularly in detecting, localizing objects, or distinguishing orientations. Electroencephalography (EEG) recordings also suggested the transmission of visual signals to the visual cortex.
Professor José-Alain Sahel, founder and former director of the Institut de la Vision, highlights these results as a significant step, demonstrating the possibility of achieving measurable visual responses by bypassing photoreceptor loss. While exploratory, these advancements open a promising path for patients with limited therapeutic options.
This publication is the result of collaboration between researchers, clinicians, and innovation stakeholders, including the Institut de la Vision, GenSight Biologics, and the Hôpital national des 15-20, coordinated by Professor Isabelle Audo. The RefeRet rare disease reference center and Streetlab participated in clinical evaluations alongside several international expert centers.
Professor Isabelle Audo, coordinator of CRMR RefeRet, emphasizes the importance of this approach for patients with advanced retinitis pigmentosa and highlights the value of clinical research conducted in close collaboration with research teams and innovation players, united within the IHU FOReSIGHT.
These results do not restore normal vision or color perception, and the visual capabilities remain partial and vary among individuals. Future research will focus on refining the glasses, optimizing the gene therapy product, and enhancing patient training programs.
