Major Breakthrough: Gene Therapy ATSN-201 Advances to Phase III for X-Linked Retinoschisis

XLRS is a monogenic X-linked disease caused by mutations in the RS1 gene, which encodes retinoschisin, a protein primarily secreted by photoreceptors. RS1 is located on the extracellular surfaces of rod cells, cone cells, and bipolar cells. XLRS is characterized by splitting or abnormal layering of the retina, leading to impaired vision that cannot be corrected with glasses, progressive vision loss, and eventual blindness. XLRS predominantly affects males and is typically diagnosed in early childhood. Approximately 30,000 males in the United States and the European Union are affected by XLRS, with no approved treatments currently available.

DMC's review conclusion fully recognized the previous safety and efficacy data of ATSN-201, laying the foundation for subsequent trials. The LIGHTHOUSE clinical trial consists of three parts (A, B, and C) and six cohorts. Part C, as the pivotal Phase III component, plans to recruit 76 XLRS patients across leading clinical institutions in North America and Europe, divided into a treatment group and a control group. Screening is set to begin in April 2026, with recruitment expected to conclude by the end of the first quarter of 2027. The data will support the submission of a Biologics License Application (BLA) in 2028.

ATSN-201 is a gene therapy developed by Atsena Therapeutics using AAV technology. It employs a novel laterally spreading capsid, SPR, which efficiently targets central retinal photoreceptors while avoiding surgical risks. As the first XLRS gene therapy to preliminarily demonstrate efficacy and safety in Phase I/II trials, the majority of patients showed significant improvements in retinal structure and visual function, with good tolerance maintained for at least one year post-treatment.

The therapy has received multiple designations from the U.S. FDA, including Regenerative Medicine Advanced Therapy (RMAT) and Fast Track, as well as Orphan Drug Designation from the European EMA, accelerating its development and market approval process. Dr. Kenji Fujita, Chief Medical Officer of Atsena Therapeutics, stated that the DMC's recommendation reflects the strength of the data, bringing them one step closer to realizing the first approved treatment for XLRS.

Global Rare Disease Drug Development Accelerates: Advancement of ATSN-201 Clinical Trials Could Fill Treatment Gap for XLRS, Offering Experience for Gene Therapy in Other Rare Diseases. The Rare Disease Information Network will continue to monitor subsequent developments, promptly relay information, and help patients gain more hope.

Source: Rare Disease Information Network