Kiora's Phase 1 ABACUS Study of KIO-301 in Retinitis Pigmentosa Published in Nature Medicine; Phase 2 Trial Underway
Rhea-AI Summary
Kiora Pharmaceuticals (NASDAQ: KPRX) reported publication of Phase 1 ABACUS-1 results for KIO-301 in Nature Medicine on April 14, 2026. The open-label, dose-escalation study dosed 12 eyes in six participants and met the primary 30-day ocular and systemic safety endpoint with no serious adverse events.
Exploratory findings included temporal changes in functional vision, light-induced fMRI activity in visual cortex, and improved participant-reported quality-of-life; a randomized, controlled Phase 2 trial (ABACUS-2) has been initiated to evaluate higher doses and functional endpoints.
Positive
- Primary safety endpoint met with no serious adverse events or dose-limiting toxicities reported
- fMRI evidence of light-induced visual cortex activation consistent with pharmacodynamic activity
- Patient-reported QoL improved over the ABACUS-1 study period
- ABACUS-2 randomized Phase 2 initiated to evaluate higher doses and controlled functional endpoints
Negative
- Very small cohort: six participants, 12 eyes limits statistical confidence
- Short follow-up: primary safety assessed only through 30 days
- Functional signals variable: temporal variation observed in light perception and vision measures
Key Figures
Previous Clinical trial Reports
| Date | Event | Sentiment | 24h Move | Catalyst |
|---|---|---|---|---|
| Mar 25 | Pipeline & earnings | Positive | -1.0% | Reported 2025 results and advanced two Phase 2 retinal trials. |
| May 05 | Preclinical data | Positive | -1.6% | Presented preclinical KIO-104 data showing reduced retinal scarring in animals. |
| Feb 11 | Trial initiation | Positive | -9.4% | Received approval to begin KLARITY, a Phase 2 trial of KIO-104. |
| Oct 29 | Trial approval | Positive | -4.7% | Received IND approval to initiate ABACUS-2 Phase 2 trial of KIO-301. |
| May 06 | Clinical data | Positive | +1.5% | Reported KIO-301 data showing increased visual cortex activity and vision gains. |
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Clinical and pipeline updates have generally been positive in tone but have often seen mildly negative next-day price moves, indicating frequent divergences between news quality and short-term trading.
Over the past year, Kiora has repeatedly highlighted progress in its retinal pipeline, including ABACUS-2 for KIO-301 and Phase 2 work on KIO-104. Prior clinical and preclinical updates, such as the May 6, 2024 visual cortex activity data and the October 29, 2024 ABACUS-2 initiation news, were largely constructive but often met with modest or negative price reactions. This Nature Medicine Phase 1 publication and ongoing Phase 2 trial continue that pattern of incremental, clinically focused advancement.
Key Terms
retinitis pigmentosa medical
intravitreally medical
functional MRI medical
optical coherence tomography medical
retinal ganglion cells medical
voltage-gated ion channels medical
pharmacodynamic medical
intraocular pressure medical
AI-generated analysis. How Rhea-AI works. Not financial advice.
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 Nature Medicine. 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 - https://www.nature.com/articles/s41591-026-04317-6
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 Nature Medicine 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 in vitro 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.
About Kiora Pharmaceuticals
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.
In addition to news releases and SEC filings, we expect to post information on our website, www.kiorapharma.com, and social media accounts that could be relevant to investors. We encourage investors to follow us on X and LinkedIn as well as to visit our website and/or subscribe to email alerts.
Forward-Looking Statements
Some of the statements in this press release are "forward-looking" and are made pursuant to the safe harbor provision of the Private Securities Litigation Reform Act of 1995. These "forward-looking" statements include statements relating to, among other things, Kiora's ability to execute on development and commercialization efforts and other regulatory or marketing approval efforts pertaining to Kiora's development-stage products, including KIO-104 and KIO-301, as well as the success thereof, with such approvals or success may not be obtained or achieved on a timely basis or at all, and the positioning of KIO-301 for potential success in clinical trials and potential commercialization. These statements involve risks and uncertainties that may cause results to differ materially from the statements set forth in this press release, including, among other things, the ability to conduct clinical trials on a timely basis, market and other conditions and certain risk factors described under the heading "Risk Factors" contained in Kiora's Annual Report on Form 10-K filed with the SEC on March 25, 2026 or described in Kiora's other public filings, including on Form 10-Q filed with the SEC on November 7, 2025. Kiora's results may also be affected by factors of which Kiora is not currently aware. The forward-looking statements in this press release speak only as of the date of this press release. Kiora expressly disclaims any obligation or undertaking to release publicly any updates or revisions to such statements to reflect any change in its expectations with regard thereto or any changes in the events, conditions, or circumstances on which any such statement is based, except as required by law.
Contacts:
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