Atsena Therapeutics Announces Positive Clinical Data for Gene Therapy to Treat X-linked Retinoschisis (XLRS)
Atsena Therapeutics announced interim data from Part A of its phase 1/2 LIGHTHOUSE clinical trial evaluating ATSN-201 for the treatment of X-linked retinoschisis (XLRS). The study demonstrated a favorable safety profile and compelling signs of efficacy in adult patients, reinforcing the potential of the company’s proprietary gene therapy platform.
ATSN-201, Atsena’s lead candidate, utilizes AAV.SPR—a novel spreading capsid engineered to safely deliver therapeutic genes to photoreceptors in the central retina without detaching the fovea, a common risk in retinal surgery. The product candidate has received multiple designations from the FDA, including Regenerative Medicine Advanced Therapy (RMAT), Fast Track, Rare Pediatric Disease, and Orphan Drug.
“The full Part A data reinforce the favorable safety profile and demonstrate encouraging structural and functional benefits across all three dose levels of ATSN-201,” Kenji Fujita, MD, Chief Medical Officer at Atsena Therapeutics, said in a company news release. “The foveal schisis closure seen in 7 of 9 treated patients is particularly exciting—it validates the potential of our AAV.SPR capsid to spread laterally and safely deliver gene therapy to the central retina.”
In Part A of the LIGHTHOUSE study, nine adult males with XLRS received subretinal injections of ATSN-201 at escalating dose levels. The treatment was well tolerated, with no serious adverse events linked to the therapy. Most adverse events were minor (Grade 1–2) and related to the surgical procedure. One unrelated serious event—a fever of unknown origin—was reported, but no dose-limiting toxicities occurred and no patients discontinued participation.
Key findings from Part A include:
Foveal schisis closure observed in 7 of 9 treated eyes, not seen in untreated eyes
67% of treated eyes (6/9) showed ≥7 dB improvement on microperimetry in the least sensitive loci
Statistically significant improvements in both Best Corrected Visual Acuity (BCVA) and Low Luminance Visual Acuity (LLVA)
Strong correlation between anatomical improvements and functional vision gains
These results were presented at the 2025 Association for Research in Vision and Ophthalmology (ARVO) and American Society for Gene and Cell Therapy (ASGCT) annual meetings.
Looking Ahead: Part B Expansion Underway
With Part A complete, enrollment is ongoing for Part B of the LIGHTHOUSE study. This next phase will include nine additional adult participants divided into three arms—low volume, high volume, and control (deferred treatment)—as well as three pediatric patients. Children will be treated following a review of safety data from the adult cohort in Part B. As with Part A, researchers will evaluate safety, macular structure, microperimetry, and visual acuity outcomes.
XLRS is a rare inherited retinal condition that predominantly affects young males and is estimated to impact approximately 30,000 individuals across the US and Europe. It is caused by mutations in the RS1 gene and typically presents in early childhood with progressive vision loss.