CIRM Awards $8M to Ray Therapeutics for Optogenetic Vision Trial

Ray Therapeutics, a Berkeley biotechnology company, is trying to make surviving retinal cells do a job they were never built for. The California Institute for Regenerative Medicine has awarded the company an $8M grant to support clinical development of RTx-015, an optogenetic gene therapy for retinitis pigmentosa. CIRM approved the award, numbered CLIN2-17086, on April 24, 2025, and currently lists it as active. The grant is non-dilutive public funding, not an equity financing round.

RTx-015 is designed to deliver a bioengineered light-sensitive protein to retinal ganglion cells, which can remain after photoreceptor loss, making those surviving cells respond to light and send a new signal into the existing visual pathway. The therapy is being tested in ENVISION, a Phase 1 open-label, non-randomized, dose-escalation study in adults with retinitis pigmentosa or choroideremia, with a single injection into one eye and planned five-year follow-up. ClinicalTrials.gov lists an actual study start date of August 27, 2024; the February 2026 registry record describes the trial as active but not recruiting, with 10 participants enrolled. Ray co-founder and CEO Paul Bresge is named as principal investigator on the grant.

Retinitis pigmentosa is a group of inherited retinal diseases in which rods and cones progressively stop working and die. Once enough photoreceptors are lost, replacing one defective gene may no longer address the practical problem in front of the patient. RTx-015 takes a mutation-independent route, which widens the theoretical patient population because it is not built around one causative mutation. But it also creates a demanding proof burden: a cell responding to light is not the same as a person recovering useful vision. The signal has to be strong enough, safe enough and stable enough for the retina and brain to turn it into function.

CIRM's award extends a public funding relationship from translational research into human testing. Ray previously received two CIRM translational grants, one supporting an optogenetic therapy for retinitis pigmentosa and other inherited retinal diseases, the other supporting work in geographic atrophy. CIRM's institution record now lists three Ray Therapeutics awards totaling $15,973,707.

The clinical evidence boundary is clear when set against the FDA-approved Luxturna, which treats patients with confirmed biallelic RPE65 mutation-associated retinal dystrophy, a narrowly defined genetic population. Ray is pursuing a different idea: restore photosensitivity downstream of the lost photoreceptors without requiring the same mutation-specific match. A September 2026 review in Gene Therapy described optogenetic vision restoration as a mutation-agnostic strategy with an expanding clinical pipeline, while also identifying unresolved translational barriers including light sensitivity, immune response, cell targeting and the absence of standardized endpoints for people with profound visual impairment.