ASRS 2026: MCO-010 optogenetic therapy sustains 3-line vision gains at 3 years in retinitis pigmentosa

MCO-010 (sonpiretigene isteparvovec; Nanoscope Therapeutics), a disease-agnostic optogenetic therapy, produced durable, clinically meaningful vision gains through 3 years in patients with severe vision loss from retinitis pigmentosa (RP), according to REMAIN follow-up data from the phase 2b/3 RESTORE (NCT04945772) trial reported at the 2026 American Society of Retina Specialists (ASRS) annual meeting. Benjamin Bakall, MD, PhD, of Associated Retina Consultants, reported the findings.

MCO-010 delivers a multi-characteristic opsin transgene through a single intravitreal adeno-associated virus (AAV2) injection, transducing intact bipolar cells so they express a photosensitive opsin and respond to light despite photoreceptor loss. In RESTORE, 27 patients received a high dose (1.2E11 gc/eye), a low dose (0.9E11 gc/eye), or sham. At the week-52 and week-76 end points, both doses produced statistically significant best-corrected visual acuity (BCVA) improvements versus sham of approximately three lines on the Freiburg visual acuity test (high dose, P = .001 at week 76).

Durability and predictors of response

At week 152—approximately 3 years—the treatment groups maintained mean BCVA gains of 0.264 ± 0.112 LogMAR (high dose) and 0.453 ± 0.140 LogMAR (low dose), sustaining the roughly 3 ETDRS-line benefit seen at the primary end points. Across the cohort, 15 distinct gene mutations were represented, and mutation type did not correlate with outcome—supporting a gene-agnostic mechanism. Better baseline BCVA and greater MCO-010 expression on fundus autofluorescence imaging positively correlated with visual gains. Patients also described functional improvements, such as identifying utensils and a plate at a table and detecting moving cars nearby.¹

Safety and outlook

MCO-010 was well-tolerated, with only mild-to-moderate, treatable inflammation and no treatment-related serious adverse events. Bakall framed the therapy as a durable option for patients with advanced RP who, in his words, "have been told nothing can be done," while cautioning against overpromising. He noted a broadening field—from roughly one inherited retinal disease trial a decade ago to more than 60 today—and pointed to potential future applications in Stargardt disease and advanced age-related macular degeneration. A biologics license application for MCO-010 in RP is underway.

Reference
1. Bakall B, Zak V, Bergstrom L, et al. Durable vision improvement with MCO-010 optogenetic therapy: 3-year REMAIN follow-up data from the RESTORE phase 2b/3 trial for retinitis pigmentosa. Presented at: American Society of Retina Specialists 44th Annual Meeting; July 15-18, 2026; Montréal, Québec, Canada. Abstract 5.