Kiora's Phase 1 ABACUS Study of KIO-301 in Retinitis Pigmentosa Published in Nature Medicine; Phase 2 Trial Underway

Encinitas, California--(Newsfile Corp. - April 14, 2026) - Kiora Pharmaceuticals (NASDAQ: KPRX) today announced the publication of the results from its Phase 1 ABACUS-1 study of KIO-301 in

. The publication adds clinical detail to a program aimed at restoring light responsiveness with a small molecule "photoswitch" in patients with the advanced inherited retinal disease, retinitis pigmentosa. The publication may be accessed at the following link - 

The open-label, first-in-human, dose-escalation trial assessed safety and feasibility in people with late-stage retinitis pigmentosa, irrespective of the underlying genetic mutation. KIO-301 was delivered intravitreally to 12 eyes in six participants. The primary endpoint was ocular and systemic safety over 30 days, with secondary and exploratory endpoints spanning functional vision testing, visual acuity, kinetic visual fields, functional MRI and participant-reported outcomes.

"Publication of the KIO-301 Phase 1 findings in

is a meaningful milestone that brings early clinical support for a molecular photoswitch into the peer-reviewed literature," said Dr. Robert Casson, Principal Investigator of the study from the Royal Adelaide Hospital. "The results of the trial provide evidence of short-term ocular safety and feasibility, while underscoring that larger, controlled studies are still needed to determine whether any functional changes translate into reliable, everyday vision benefit."

"Based on Phase 1 results, we initiated a randomized, controlled Phase 2 clinical trial, dubbed ABACUS-2," said Brian M. Strem, Ph.D., President and Chief Executive Officer of Kiora. "The trial is designed to evaluate higher doses of KIO-301 with the goal of measuring, among other endpoints, functional visual improvements and comparing them to a control group, who will be eligible for KIO-301 treatment as part of an open-label extension. We appreciate the invaluable participation of patients, along with work by our team, investigators and the strategic and financial support from our development and commercialization partner(s), including Théa Open Innovation."

As described in the publication, the primary safety outcome was met with no serious adverse events nor dose-limiting toxicities, drug-related intraocular inflammation, nor structural retinal changes (as assessed by autofluorescence or optical coherence tomography). Reported ocular adverse events were described as mild and transient and consistent with known effects of intravitreal injection procedures, including transient discomfort and mild elevations in intraocular pressure in a single patient.

Secondary and Exploratory Endpoints in ABACUS-1

	What was evaluated	Reported result
Participants/dosing	Six participants; 12 eyes; intravitreal	Dosed eyes monitored for 30 days
Primary endpoint	Ocular & systemic safety > 30 days	Met
Functional vision	Light perception and functional vision measures	Temporal variation observed in some participants
Neuroimaging	fMRI BOLD signal in visual cortex	Light-induced changes consistent with pharmacodynamic activity
Patient-reported outcomes	Quality-of-life measures	Scores improved over study period

 

"The science of molecular photoswitches, including KIO-301, has come a long way from our early research at the University of Washinton and UC Berkeley to a successful Phase 1 study and ongoing Phase 2 randomized, controlled trial," said Russell N. Van Gelder, M.D., Ph.D., Professor and Chair, Department of Ophthalmology, University of Washington School of Medicine. "This publication reflects this progress and ongoing need to determine, with additional trials, if these early signals translate into consistent functional benefit."

Exploratory assessments identified temporal variation in light perception and functional vision measures in some participants. The researchers also reported light-induced changes in neural activity (using functional MRI) within the visual cortical region of the brain following dosing, with a time course consistent with the pharmacodynamic activity window. Participant-reported quality-of-life scores also showed improvements during the study period.

KIO-301 is a small molecule designed to include a light-reactive azobenzene. Its mechanism of action, based on preclinical and

research, suggests it preferentially targets and enters retinal ganglion cells downstream of degenerated photoreceptors. From here, it renders voltage-gated ion channels responsive to light, causing neural activation and direct signaling to the brain. This MOA is potentially applicable to patients with multiple types of retinal degeneration irrespective of the underlying gene mutation or age-related cause. The authors noted that repeated intravitreal injections are widely used in retinal care as part of in-office procedures and this dosing regimen is incorporated into the ABACUS-2 trial.

Kiora Pharmaceuticals is a clinical-stage biotechnology company developing advanced therapies for retinal disease. We target critical pathways underlying retinal diseases using innovative small molecules to slow, stop, or restore vision loss. KIO-104 is being developed for the treatment of retinal inflammation. It is a next-generation, non-steroidal, immuno-modulatory, and small-molecule inhibitor of dihydroorotate dehydrogenase (DHODH). KIO-301 is being developed for the treatment of retinitis pigmentosa, choroideremia, and Stargardt disease. It is a molecular photoswitch that has the potential to restore vision in patients with inherited and/or age-related retinal degeneration.