Phase 1 trial of intravitreal photoswitch (KIO-301/BENAQ) in advanced retinitis pigmentosa published in Nature Medicine

A first-in-human phase 1 trial of intravitreal photoswitch therapy in advanced retinitis pigmentosa has been published in Nature Medicine. The trial used KIO-301, an intravitreal formulation of the photoswitch molecule BENAQ, which selectively enters retinal ganglion cells downstream of degenerated photoreceptors and renders endogenous voltage-gated channels light-sensitive without genetic manipulation.

Headline findings: a favorable safety and tolerability profile with no serious or definite drug-related adverse events, and exploratory signals consistent with light responsiveness — including a participant with no light perception at baseline who recovered light perception by 2 days post-injection, accompanied by enhanced fMRI signals in primary visual cortex within 2–14 days.

This is an important moment for our field and a direct point of reference for the Fortenbach Lab’s work on the circuit-level properties of photoswitch-mediated vision. The clinical results raise — rather than answer — the questions our lab is built to address: what kind of vision does photoswitch therapy actually produce, and how can we make it better?

Read the paper: Intravitreal photoswitch therapy in advanced retinitis pigmentosa: a phase 1 open-label trial (Nature Medicine, 2026).