FDA Grants Fast Track for Atsena's ATSN-201 Gene Therapy for X-linked Retinoschisis

On March 12, 2025, Atsena Therapeutics, a clinical-stage gene therapy enterprise, revealed that the U.S. Food and Drug Administration (FDA) has awarded a Fast Track designation to ATSN-201, its pioneering gene therapy candidate, for treating X-linked retinoschisis (XLRS). This innovative therapy uses the company’s breakthrough spreading capsid, AAV.SPR, to deliver therapeutic gene expression levels in the central retina's photoreceptors without the surgical risks associated with foveal detachment.

Patrick Ritschel, CEO of Atsena Therapeutics, expressed satisfaction with the FDA's decision, emphasizing that the Fast Track designation highlights ATSN-201's potential to address the unmet medical needs of XLRS, a rare inherited retinal disease lacking approved treatments. This designation complements previously awarded Orphan Drug and Rare Pediatric Disease designations, marking a significant milestone in advancing ATSN-201's development. Atsena is steadfast in its mission to create transformative gene therapies that enhance the quality of life for individuals affected by XLRS and other inherited retinal diseases.

Fast Track designation is reserved for drugs addressing serious or life-threatening conditions and demonstrating the potential to satisfy unmet medical needs. This designation facilitates more frequent interactions with the FDA during the drug development process and may also qualify treatments for Priority Review if certain criteria are fulfilled.

XLRS, which predominantly affects males, is usually diagnosed in early childhood and impacts roughly 30,000 individuals in the U.S. and EU. At present, no approved treatments exist for this condition. The safety and tolerability of ATSN-201 are being assessed in the ongoing LIGHTHOUSE study, a Phase I/II clinical trial involving male patients aged six and older diagnosed with XLRS due to RS1 gene mutations. This study is currently open for enrollment.

XLRS is a monogenic, X-linked disorder caused by mutations in the RS1 gene, which encodes retinoschisin, a protein primarily secreted by photoreceptors. The disease is marked by schisis, or the abnormal splitting of retinal layers, leading to reduced visual acuity that cannot be corrected with glasses, resulting in progressive vision loss and eventual blindness.

Atsena's AAV.SPR capsid is engineered to spread laterally beyond the subretinal injection site, enabling safe and efficient transduction of the central retina where schisis cavities are prevalent in XLRS patients. In preclinical studies involving non-human primates, AAV.SPR demonstrated enhanced transgene expression beyond the initial bleb margins, unlike conventional AAV vectors. At clinically relevant doses, AAV.SPR transduces foveal cones efficiently without requiring surgical detachment and exhibits a favorable safety profile compared to standard capsids.

Atsena Therapeutics is at the forefront of developing gene therapies aimed at reversing or preventing blindness caused by inherited retinal diseases. The company is leading efforts with ATSN-201 in an ongoing clinical trial to address XLRS, a genetic disorder often diagnosed in childhood that can result in blindness. Additionally, Atsena is advancing ATSN-101, an investigational gene therapy for Leber congenital amaurosis type 1 (LCA1), towards a global pivotal trial in collaboration with Nippon Shinyaku Co., Ltd., following positive results from a completed Phase 1/2 trial. Atsena's innovative pipeline is supported by new adeno-associated virus (AAV) technology designed to overcome challenges posed by inherited retinal diseases, with leadership from pioneers in ocular gene therapy committed to meeting the needs of patients experiencing vision loss.