Atsena Aligns with FDA on Regulatory Pathway for ATSN-201 in XLRS

Atsena Therapeutics has announced a key regulatory milestone, reporting that the US Food and Drug Administration (FDA) has agreed to expand the ongoing phase 1/2 LIGHTHOUSE study of ATSN-201 into a continuous phase 1/2/3 trial. This change allows the study to serve as a pivotal trial supporting a future Biologics License Application (BLA) submission for the treatment of X-linked retinoschisis (XLRS). Atsena anticipates submitting the BLA in early 2028.

Accelerating the Path to Potential First Treatment for XLRS

“This regulatory milestone marks another significant step toward delivering a potentially first- and best-in-class gene therapy for patients living with XLRS,” said Patrick Ritschel, MBA, Chief Executive Officer of Atsena Therapeutics. “The agency’s agreement will expedite the clinical development of ATSN-201 by at least 1.5 years, compared to a separate phase 3 clinical trial. If approved, this would be the first available treatment for XLRS, offering hope to patients and families affected by this inherited retinal disease. We’re grateful for the FDA’s continued guidance as we advance this trial and prepare for filing a BLA in early 2028.”

Regulatory Support and Expanded Study Design

ATSN-201 has received Regenerative Medicine Advanced Therapy (RMAT), Fast Track, Rare Pediatric Disease, and Orphan Drug Designations from the FDA. This recent regulatory advancement follows an RMAT meeting during which the agency agreed on the proposed study design, endpoints, and patient population to support potential registration.

The LIGHTHOUSE study will now include an additional cohort of approximately 30 adult and pediatric patients, randomized 1:1 between treatment and control groups. Patients in the control arm will have the opportunity to receive treatment after one year. The study will assess efficacy and safety across all patients using measures such as microperimetry, visual acuity, and macular structure.

The pivotal cohort is expected to begin enrollment in the first quarter of 2026, with pivotal data anticipated in the second half of 2027.

Promising Early Data and First Use of Novel Vector

Kenji Fujita, MD, Chief Medical Officer of Atsena Therapeutics, highlighted the program’s progress:

“Data from the ongoing trial show that subretinal delivery of ATSN-201 has been well tolerated to date, including in patients with severe schisis cavities, and has led to encouraging improvements in both retinal structure and visual function. This program marks the first clinical use of our laterally spreading subretinal vector, offering important proof of principle for our ocular gene therapy platform. With the study’s expansion, we’re positioned to generate the pivotal data needed to potentially bring the first treatment for XLRS across the finish line.”

About XLRS and the LIGHTHOUSE Study

XLRS is an inherited retinal disease typically diagnosed in early childhood, affecting approximately 30,000 males in the US and EU combined. There are currently no approved treatments for this condition.

The LIGHTHOUSE study is a dose-escalation and dose-expansion clinical trial enrolling male patients aged 6 and older with a clinical diagnosis of XLRS caused by mutations in the RS1 gene. Enrollment for the study remains ongoing.