Atsena Therapeutics recently announced that the first patient has been dosed in the phase 3 LIGHTHOUSE trial evaluating ATSN-201 for the treatment of x-linked retinoschisis (XLRS).
First up: ATSN-201.
Atsena’s lead asset is ATSN-201, a subretinal gene therapy under development for both XLRS and USH1B, that utilizes AAV.SPR, one of Atsena’s novel capsids that holds a key role in treating XLRS.
How: Efficient transduction of foveal cones without the need for surgical detachment and a favorable safety profile relative to benchmark capsids.
Note: ATSN-201 has received four FDA designations over the past 2 years, including:
- Regenerative Medicine Advanced Therapy (RMAT; April 2025)
- Fast Track (March 2025)
- Orphan Drug (September 2024)
- Rare Pediatric Disease (August 2024)
Give me a refresher on the technology behind ATSN-201.
The next-generation, adeno-associated virus (AAV) technologies feature novel, laterally-spreading capsids, dual vectors, and intravitreal capsids that deliver larger payloads for genetic mutations that are too large to treat with a single AAV vector.
In other words: The capsid spreads laterally beyond the subretinal injection site (bleb margins) to safely deliver retinoschisin (RS1) to photoreceptors within the central retina/fovea.
- Click here to learn more about the mechanism of action behind AAV.SPR.
Any recent news on the candidate?
Indeed. In May 2026, the company released interim 6-month results from Part B of the LIGHTHOUSE trial:
- Foveal schisis closure at Month 6 was confirmed in 4 of 6 treated adults (67%) in cohort 4
- Meaningful improvements in retinal and visual function as assessed by microperimetry, best-corrected visual acuity and low-luminance visual acuity
- A favorable safety profile was observed across all Part B cohorts with no serious adverse events (SAEs), instances of macular hole formation or retinal detachment, and no subject discontinuations
Let’s move on to this LIGHTHOUSE trial.
Originally initiated in 2023 with plans to conclude in 2028, this phase 1/2/3 open-label, dose-escalation, and dose-expansion trial (NCT05878860) consists of three parts (A, B, and C) and six cohorts.
Note: The phase 1/2 portion includes cohorts 1-3 (Part A) and cohorts 4-5 (Part B), while cohort 6 (Part C) will serve as the phase 3 portion of the study.
- Click here for more information on the set up of the LIGHTHOUSE trial.
So about this most recent update …
The phase 3 pivotal portion of the LIGHTHOUSE trial is enrolling 76 patients with XLRS, including both adults and children as young as 6, across medical centers in North America and Europe.
Since beginning enrollment in May, Atsena has already enrolled 10% of the study and expects rapid continued enrollment as additional planned sites are activated across North America and Europe.
When can we expect updates?
The company anticipates completing enrollment by the end of Q1 2027, with topline results anticipated in H1 2028.
Pending positive data: A Biologics License Application (BLA) filing is targeted for H2 2028.
Any comments from Atsena about this milestone?
“Brisk enrollment of the study reflects the significant unmet need in XLRS, a disease for which no approved treatments exist, and strong interest from leading clinicians and patients who have been following ATSN-201’s clinical progress,” stated Kenji Fujita, MD, chief medical officer of Atsena.
- “That interest is grounded in compelling early clinical results. The majority of treated patients in the phase 1/2 portion of the LIGHTHOUSE trial demonstrated closure of schisis cavities and meaningful improvements in retinal and visual function at levels consistent with FDA approvability, outcomes that have proven durable through at least one year of follow-up.”
Any other news from Atsena?
You may remember that back in 2024 the company entered an exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. for the development and commercialization of ATSN-101, its first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1).
Since then, Atsena has completed a phase 1/2 trial (NCT03920007) with positive results and expects to initiate a global pivotal phase 3 trial evaluating the candidate in H2 2026.