FDA Grants RMAT Designation to ATSN-201 Gene Therapy for XLRS

The US Food and Drug Administration (FDA) has granted Regenerative Medicine Advanced Therapy (RMAT) designation to ATSN-201 gene therapy, a first-of-its-kind treatment for X-linked retinoschisis (XLRS).1

Announced by Atsena Therapeutics on April 15, 2025, ATSN-201 has previously been granted Fast Track, Rare Pediatric Disease, and Orphan Drug designations. With the addition of RMAT, the FDA is now directly guiding the development process, including potentially granting Priority Review to the drug’s biologics license application (BLA).1

A treatment is considered eligible for RMAT if intended to treat, reverse, cure, or modify a life-threatening or serious disease or condition. In addition, the treatment must exhibit the potential to address unmet medical needs for that condition or disease.1

“We’re honored that the FDA has granted Regenerative Medicine Advanced Therapy (RMAT) designation to ATSN-201, further underscoring its potential to address the urgent, unmet need in XLRS,” said Patrick Ritschel, chief executive officer of Atsena Therapeutics.1

XLRS is an inherited genetic disorder that primarily affects males, caused by mutations in the RS1 gene that lead to abnormal retinal layer separation and visual impairment that cannot be corrected with glasses. Roughly 30,000 male patients in the US and EU are affected by XLRS, and it has no approved treatments.1

ATSN-201 makes use of Atsena’s novel capsid AAV.SPR, which spreads around the injection site to allow for safe and efficient transduction of the central retina. Previous trials have indicated that AAV.SPR is capable of transducing foveal cones without surgical detachment and has a favorable safety profile compared to benchmark capsids.1

In December 2024, Atsena Therapeutics announced completion of Part A of their LIGHTHOUSE study, a Phase I and II trial to evaluate subretinal injection of ATSN-201 to treat XLRS. Part A evaluated the safety and efficacy of 3 dose levels of ATSN-201, including 9 adult participants with XLRS. There were no reports of adverse effects linked to the trial, and this initial portion demonstrated structural and functional benefits at all dose levels.2

Part B of the trial commenced in January of 2025, which took the form of a multicenter clinical trial evaluating 9 additional adults and 3 children with XLRS. Investigators will break participants into three major groups: high volume, low volume, and control. The control arm will be observed off-therapy for one year and then have the opportunity for treatment. The pediatric cohort will be dosed after data from the adult cohort have been evaluated. Enrollment for this portion of the trial is ongoing as of April 2025.3

“This regulatory momentum, coupled with the recent close of our oversubscribed $150 million Series C financing, reinforces our commitment to advancing meaningful gene therapies that have the potential to improve vision and quality of life for individuals living with XLRS and other inherited retinal diseases,” Ritschel said.1

References

1. Haserick B. Atsena Therapeutics granted U.S. FDA Regenerative Medicine Advanced Therapy Designation for ATSN-201 Gene Therapy to treat X-linked retinoschisis. Atsena Therapeutics. April 15, 2025. Accessed April 15, 2025. https://atsenatx.com/press-release/atsena-therapeutics-granted-us-fda-regenerative-medicine-advanced-therapy-designation-for-atsn-201-gene-therapy-to-treat-x-linked-retinoschisis/

2. Haserick B. Atsena Therapeutics announces dosing completed in part A of phase I/II clinical trial evaluating Gene Therapy ATSN-201 to treat X-linked retinoschisis. Atsena Therapeutics. December 16, 2024. Accessed March 12, 2025. https://atsenatx.com/press-release/atsena-therapeutics-announces-dosing-completed-in-part-a-of-phase-i-ii-clinical-trial-evaluating-gene-therapy-atsn-201-to-treat-x-linked-retinoschisis/.

3. Haserick B. Atsena Therapeutics initiates part B of phase I/II clinical trial evaluating Gene Therapy ATSN-201 to treat X-linked retinoschisis. Atsena Therapeutics. January 8, 2025. Accessed March 12, 2025. https://atsenatx.com/press-release/atsena-therapeutics-initiates-part-b-of-phase-i-ii-clinical-trial-evaluating-gene-therapy-atsn-201-to-treat-x-linked-retinoschisis/.