Key Takeaways

  • At 18 months, 7 of 9 ATSN-201-treated eyes maintained foveal schisis closure, while 6 of 9 achieved at least a 7-dB improvement in microperimetry
  • No drug-related serious adverse events, dose-limiting toxicities, or patient discontinuations were reported among the 9 adults in Part A of the LIGHTHOUSE trial
  • Enrollment in the pivotal Phase 3 Part C cohort is ongoing, with topline results anticipated in the first half of 2028 and a potential BLA filing targeted for the second half of that year

Atsena Therapeutics has reported 18-month safety and efficacy findings from Part A of the phase 1/2/3 LIGHTHOUSE trial evaluating ATSN-201 gene therapy in patients with X-linked retinoschisis (XLRS).

The results were presented by Laura Pardon, OD, PhD, associate director of clinical development at Atsena Therapeutics, during the American Academy of Optometry 2026 annual meeting, held September 30 to October 3 in Anaheim, California. The abstract was also selected for presentation during the meeting’s Innovations in Vision and Eye Care press conference.

Part A evaluated 3 doses of ATSN-201 administered by subretinal injection to 1 eye of each participant. Three patients were enrolled in each dose cohort, for a total of 9 adult patients.

At 18 months, foveal schisis closure was maintained in 7 of 9 treated eyes, according to Atsena. The company reported that closure was not observed in the untreated fellow eyes. Treated eyes also demonstrated statistically significant improvements in central retinal thickness, microperimetry, best-corrected visual acuity (BCVA), and low-luminance visual acuity (LLVA), the company reported.

Six of 9 treated eyes achieved an improvement of at least 7 dB on microperimetry at 18 months, compared with none of the 9 untreated eyes. The 7-dB responder threshold is also being used for the primary endpoint in the pivotal Part C portion of LIGHTHOUSE. In addition, 7 of 9 treated eyes achieved an improvement of at least 10 letters in either BCVA or LLVA at 18 months, compared with 1 of 9 untreated eyes.

“We are encouraged by these Part A results, which reinforce ATSN-201’s ability to deliver durable structural and functional improvements for patients with XLRS,” Kenji Fujita, MD, chief medical officer of Atsena Therapeutics, said in the company’s announcement.

Dr. Fujita noted that the foveal schisis findings and improvements in visual function have been sustained through at least 18 months following treatment.

The company also reported that ATSN-201 continued to be well tolerated across the 9-patient Part A cohort. There were no drug-related serious adverse events, dose-limiting toxicities, or patient discontinuations.

Because Part A enrolled only 9 patients and was designed primarily to assess safety and tolerability across different dose levels, the efficacy findings will require confirmation in the larger pivotal portion of the study.

Enrollment is ongoing in Part C of LIGHTHOUSE, the pivotal phase 3 cohort. Atsena expects enrollment to be completed by the end of the first quarter of 2027, with topline results anticipated in the first half of 2028. The company said data from the Phase 3 cohort are expected to support a Biologics License Application filing for ATSN-201, which is targeted for the second half of 2028.