Atsena Therapeutics Announces Dosing Complete for Adults in Part B of the Phase I/II/III LIGHTHOUSE Trial Evaluating ATSN-201 to Treat X-linked Retinoschisis

Pediatric dosing expected to begin in Q4 2025

Pivotal cohort expected to begin enrolling in Q1 2026

BLA submission anticipated in early 2028

Part A results demonstrated efficacy and safety; ATSN-201 on track to be first gene therapy and one-time treatment for XLRS

DURHAM, N.C., Sept. 23, 2025 (GLOBE NEWSWIRE) -- Atsena Therapeutics, a clinical-stage gene therapy company focused on using the life-changing power of genetic medicine to reverse or prevent blindness, today announced that dosing is complete in adults enrolled in Part B of the LIGHTHOUSE study, the Phase I/II/III clinical trial evaluating subretinal injection of ATSN-201 for the treatment of X-linked retinoschisis (XLRS). Based on the evaluation of preliminary data from the adult cohort, dosing of the pediatric patients is expected to begin in the fourth quarter of 2025, pending approval from the Data Monitoring Committee.

“Dosing of adult patients in all groups of Part B is now complete, and follow-up is ongoing,” said Kenji Fujita, MD, Chief Medical Officer of Atsena Therapeutics. “Preliminary safety data remain favorable, and early structural and functional readouts, including improvements in foveal schisis and retinal sensitivity, are consistent with the positive signals observed in Part A. These findings will enable initiation of pediatric dosing, a critical next step in assessing the full therapeutic potential of ATSN-201 across the XLRS patient population.”

Part B of the ongoing multicenter clinical trial is evaluating a total of nine adults and three pediatric patients with XLRS. Adults are separated into three groups: low volume, high volume and control. Patients in the control group will be observed off-therapy for one year and then have the option to receive treatment. In July 2025, the U.S. Food and Drug Administration (FDA) agreed to the expansion of the study to serve as a pivotal trial and support a Biologics License Application (BLA), anticipated in early 2028.

“Completing adult dosing in Part B of the LIGHTHOUSE study represents a meaningful milestone as we advance ATSN-201 through the pivotal trial pathway,” said Patrick Ritschel, MBA, Chief Executive Officer of Atsena Therapeutics. “The FDA’s alignment on our trial design underscores the growing momentum behind this program. With no approved therapies, we remain committed to progressing this potential first- and best-in-class gene therapy as rapidly and rigorously as possible to patients with XLRS.”

About X-linked Retinoschisis (XLRS)
XLRS is a monogenic X-linked disease caused by mutations in the RS1 gene which encodes retinoschisin, a protein secreted primarily by photoreceptors. RS1 is localized to the extracellular surface of rods, cones and bipolar cells. XLRS is characterized by schisis, or abnormal splitting of retinal layers, which causes impaired visual acuity that is not correctable with glasses and leads to progressive vision loss and ultimately blindness. XLRS primarily affects males and is typically diagnosed in early childhood. Approximately 30,000 males in the U.S. and EU have XLRS, for which there are currently no approved treatments.

About ATSN-201
ATSN-201 is Atsena’s investigational gene therapy leveraging AAV.SPR, a novel, laterally spreading capsid designed to efficiently target photoreceptors in the central retina while avoiding the surgical risks of foveal detachment. It is currently being evaluated in the Phase I/II/III LIGHTHOUSE Trial which consists of three parts (A, B and C) and six cohorts. The Phase I/II portion includes cohorts 1-3 (Part A) and cohorts 4-5 (Part B), while the remaining cohort 6 (Part C) will serve as the Phase III portion of the study.

ATSN-201 is the first XLRS gene therapy to demonstrate efficacy and positive safety data in a Phase I/II trial, with the majority of patients demonstrating improvements in retinal structure (foveal schisis closure) and meaningful improvements in retinal and visual function as assessed by microperimetry, best-corrected visual acuity and low-luminance visual acuity. ATSN-201 has demonstrated a favorable safety profile and has been well-tolerated for at least one year post-treatment with no serious adverse events reported to date. If approved, ATSN-201 will be the first gene therapy approved for XLRS. The best-in-class gene therapy product candidate has received Regenerative Medicine Advanced Therapy, Fast Track, Rare Pediatric Disease and Orphan Drug Designations from the U.S. Food and Drug Administration. Enrollment for this study is ongoing. For more information, visit ClinicalTrials.gov (Identifier: NCT05878860).

About AAV.SPR
AAV.SPR, one of Atsena’s novel capsids, spreads laterally beyond the subretinal injection site to enable safe and efficient transduction of the central retina (where schisis cavities predominate in XLRS patient retinas) when injected into areas outside the macula. A preclinical study in non-human primates demonstrated that AAV.SPR promotes transgene expression well beyond subretinal injection bleb margins. This is in contrast to benchmark AAV vectors, which remain confined to the original bleb margins. At clinically relevant doses, AAV.SPR efficiently transduces foveal cones without the need for surgical detachment and has a favorable safety profile relative to benchmark capsids. For more information about the preclinical study and how AAV.SPR works, visit https://atsenatx.com/our-approach/laterally-spreading-aav/.

About Atsena Therapeutics
Atsena Therapeutics (“Atsena”) is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 in an ongoing Phase I/II/III clinical trial for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. ATSN-101, Atsena’s first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1) has completed a Phase I/II trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8). Atsena is advancing ATSN-101 toward the initiation of a global pivotal trial as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. Atsena’s pipeline is powered by novel adeno-associated virus (AAV) technology tailored to overcome the hurdles presented by inherited retinal diseases. Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

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