Atsena Therapeutics Advances to Pivotal Phase 3 Trial for X-Linked Retinoschisis

Atsena Therapeutics has reached a significant milestone in its development of ATSN-201, an investigational gene therapy for X-linked retinoschisis (XLRS). The independent Data Monitoring Committee (DMC) for the ongoing LIGHTHOUSE trial has completed its review of safety and efficacy data from the study's early phases and recommended that the company proceed with the pivotal Phase 3 portion of the trial.

Patient screening for the registration-enabling study begins this month, bringing the potential first approved therapy for XLRS one step closer to patients.

XLRS is a genetic eye disease that primarily affects males and is typically diagnosed in early childhood. Caused by mutations in the RS1 gene, the condition leads to abnormal splitting of retinal layers, which causes progressive vision loss that cannot be corrected with glasses. The disease affects approximately 30,000 males in the United States and the European Union and currently has no approved treatments available.

ATSN-201 represents a breakthrough in treating XLRS through its unique delivery system. The therapy uses AAV.SPR, a novel capsid that spreads laterally beyond the subretinal injection site to efficiently target photoreceptors in the central retina. This innovative approach allows treatment of the critical foveal area while avoiding the surgical risks associated with foveal detachment.

In earlier phases of the LIGHTHOUSE trial, ATSN-201 became the first XLRS gene therapy to demonstrate preliminary evidence of both safety and efficacy. The majority of treated patients showed improvements in retinal structure, including closure of foveal schises, as well as meaningful improvements in visual function measures.

The pivotal Phase 3 portion will enroll 76 patients across clinical sites in North America and Europe. The study will compare treated patients with a control group, with control patients having the option to receive treatment after a 12-month observation period. Enrollment is expected to be completed by the end of the first quarter of 2027, with data from this phase supporting a Biologics License Application filing in 2028.

"We're not surprised to see Atsena's XLRS program advance to this pivotal phase," said Rusty Kelley, Managing Director of the RD Fund. "The DMC's recommendation to proceed reflects the strength of the safety and efficacy data accumulated to date and brings us one step closer to an approved therapy for XLRS patients.”

The RD Fund, the venture arm of the Foundation Fighting Blindness, was a seed investor in Atsena and has participated in every financing round, including the most recent Series C round led by Bain Capital.

ATSN-201 has received significant regulatory support, including Regenerative Medicine Advanced Therapy, Fast Track, Rare Pediatric Disease, and Orphan Drug designations from the FDA, as well as Orphan Designation from the European Medicines Agency.