FDA Picks Abeona’s XLRS Gene Therapy ABO-503 for RDEA Pilot Program

Abeona Therapeutics’ ABO-503, an investigational adeno-associated virus (AAV) vector-based gene therapy intended to treat X-linked retinoschisis (XLRS), has been chosen by the FDA for its Rare Disease Endpoint Advancement (RDEA) Pilot Program.¹

The RDEA program is meant to support use of novel end points for measuring efficacy in clinical studies for therapies aimed at treating rare diseases. It will allow the company to obtain frequent advice from the FDA and have conversations as needed with the agency in order to help establish product-specific efficacy end points for the program.

“XLRS is an underserved area with a large unmet need,” Vish Seshadri, PhD, the chief executive officer of Abeona, said in a statement.¹ “We are honored that ABO-503 gene therapy for XLRS has been chosen for the FDA’s highly competitive RDEA pilot program. We believe our participation will meaningfully improve the success rate of our XLRS clinical development efforts, and more broadly, could help facilitate pipeline innovation by using novel efficacy end points in new therapy development across other inherited retinal diseases.”

ABO-503 uses a novel capsid referred to as AAV204 and is intended to deliver a functional copy of the human RS1 gene. The therapy is currently in preclinical development, but Abeona expects that by the second half of next year investigational new drug (IND)-enabling studies will be finished. In a mouse model of XLRS, ABO-503 showed efficacy when administered to the retina. Furthermore, improvements in cone photoreceptor density and overall photoreceptor cell survival, elimination of XLRS-characteristic cysts, and betterment of visual function were seen in preclinical studies.

ABO-503 is not the only gene therapy product currently in development for XLRS. Atsena Therapeutics ATSN-201, an investigational AAV gene therapy, is currently being evaluated in the phase 1/2/3 LIGHTHOUSE clinical trial (NCT05878860) for patients with XLRS associated with mutations in the RS1 gene.² In September of this year, Atsena finished dosing adult patients in part B of LIGHTHOUSE. Part B of LIGHTHOUSE enrolled 9 adult patients and is expected to enroll 3 pediatric patients. At the time of the announcement, Atsena stated its expectation that it will begin recruitment of pediatric patients in the final quarter of this year if the study’s data monitoring committee gives a green light. The adult patients participating in the trial were assigned to either a low-volume group, a high-volume group, or a control group, with the patients in the control group having the choice to receive ATSN-201 after 1 year of observation.

“Dosing of adult patients in all groups of part B is now complete, and follow-up is ongoing,” Kenji Fujita, MD, the chief medical officer of Atsena Therapeutics, said in a September 2025 statement.² “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.”

Although Abeona’s XLRS program is less far along than Atsena’s, Abeona notably has an FDA gene therapy approval under its belt already in the form of prademagene zamikeracel (pz-cel, marketed as Zevaskyn), an autologous gene-corrected epidermal sheet therapy approved for the treatment of patients with recessive dystrophic epidermolysis bullosa (RDEB).³ The dermatological therapeutic garnered the approval in April of this year, with the FDA’s decision having been based on results from the phase 3 VIITAL clinical trial (NCT04227106) and a phase 1/2a clinical (NCT01263379), both of which are now completed.⁴

“Zevaskyn was well-tolerated and efficacious in clinical studies, providing clinically meaningful improvements in wound healing, pain reduction, and other associated symptoms in large chronic RDEB wounds after a single application,” lead principal investigator of VIITAL Jean Tang, MD, PhD, a professor of dermatology, said in a statement at the time of the approval.³ “In the completed phase 1/2a study of Zevaskyn, we have observed wound healing and pain reduction that have lasted for years after a single application. Today we can celebrate the availability of an exciting new therapeutic option made possible by the incredible courage of patients and families who participated in these clinical studies.”

REFERENCES
1. Abeona Therapeutics® announces ABO-503 gene therapy for X-linked retinoschisis (XLRS) selected by FDA for rare disease endpoint advancement (RDEA) pilot program. News release. Abeona Therapeutics Inc. October 13, 2025. Accessed October 14, 2025. https://investors.abeonatherapeutics.com/press-releases/detail/323/abeona-therapeutics-announces-abo-503-gene-therapy-for
2.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. News release. Atsena Therapeutics. September 23, 2025. Accessed October 14, 2025. https://atsenatx.com/press-release/atsena-therapeutics-announces-dosing-complete-in-adults-in-part-b-of-the-phase-i-ii-iii-lighthouse-trial-evaluating-atsn-201-to-treat-x-linked-retinoschisis/
3. US FDA approves ZEVASKYN™ (prademagene zamikeracel), the first and only cell-based gene therapy for patients with recessive dystrophic epidermolysis bullosa (RDEB). News release. Abeona Therapeutics Inc. April 29, 2025. Accessed April 29, 2025. https://investors.abeonatherapeutics.com/press-releases/detail/303/u-s-fda-approves-zevaskyn-prademagene-zamikeracel
4. Abeona Therapeutics Provides Regulatory Update on Pz-cel. News release. Abeona Therapeutics. April 22, 2024. Accessed October 14, 2025. https://finance.yahoo.com/news/abeona-therapeutics-provides-regulatory-pz-200500676.html