Atsena Therapeutics Selects ATSN-401 Clinical Candidate, a Potential Best-in-Class Gene Therapy for Stargardt Disease

Proprietary dual-vector platform delivers full-length ABCA4, enabled by Atsena's laterally spreading AAV.SPR capsid for delivery to the central retina without 
foveal detachment

ATSN-401 advancing in IND-enabling studies

DURHAM, N.C., July 09, 2026 (GLOBE NEWSWIRE) -- Atsena Therapeutics, a clinical-stage gene therapy company focused on reversing and preventing blindness from inherited retinal diseases, today announced the selection of a lead clinical candidate for ATSN-401, a potential best-in-class gene therapy for Stargardt disease (STGD), the most common inherited macular dystrophy. Atsena is now advancing ATSN-401 in IND-enabling studies.

“For patients with Stargardt disease, there is no approved treatment that addresses the underlying cause, and we believe ATSN-401 has the potential to change that," said Patrick Ritschel, Chief Executive Officer of Atsena. "This program is powered by two proprietary technologies: AAV.SPR, our laterally spreading capsid, which is in a pivotal Phase 3 clinical trial in XLRS, and our dual vector DNA recombination platform, which has achieved above-wildtype gene expression in primate retina in our ATSN-301 USH1B program. With our XLRS and LCA1 programs in late-stage clinical development, and our pipeline candidates for USH1B and Stargardt also advancing toward the clinic, we believe Atsena is well positioned for sustained growth.”

"Our clinical candidate for ATSN-401 stood out clearly across our criteria of expression, efficacy, and safety in both mouse and primate models,” said Shannon Boye, Ph.D., Chief Scientific Officer of Atsena. “We saw robust, properly localized ABCA4 expression, meaningful bisretinoid reduction at well-tolerated doses, and spreading behavior from AAV.SPR that confirms the capsid reaches the central retina from a peripheral injection site. That last point is critical for Stargardt patients: the ability to avoid injecting into a dystrophic macula is not just a surgical convenience, it is a potential safety advantage that we believe will be an important differentiator for ATSN-401.”

Stargardt disease is the most common inherited macular dystrophy, affecting approximately 60,000 patients in the United States, Canada, and the European Union. It is caused by mutations in the ABCA4 gene, which encodes a transporter expressed in photoreceptors. Loss of functional ABCA4 leads to accumulation of toxic bisretinoid compounds in the retinal pigment epithelium (RPE), driving progressive photoreceptor and RPE cell death and bilateral central vision loss that typically begins in the first decade of life. There are currently no approved treatments addressing the underlying genetic cause.

ATSN-401 is designed to deliver full-length, functional ABCA4 to photoreceptors in the central retina. Because the ABCA4 coding sequence exceeds the capacity of a single adeno-associated virus (AAV) vector, Atsena's proprietary dual vector DNA recombination platform splits the gene across two vectors; upon co-transduction, the halves recombine at the DNA level to produce full-length ABCA4 mRNA and protein, directly targeting the root cause of bisretinoid accumulation. ATSN-401 also employs Atsena's AAV.SPR laterally spreading capsid, which has demonstrated its unique lateral spreading capability in human subjects in the ongoing Phase 1/2/3 LIGHTHOUSE clinical trial evaluating ATSN-201 for X-linked retinoschisis (XLRS). AAV.SPR spreads beyond peripheral injection sites to transduce photoreceptors throughout the central retina, allowing retinal specialists to avoid surgical detachment of the dystrophic macula, a step required with conventional capsids. Preclinical studies in mouse and non-human primate models demonstrated robust, properly localized ABCA4 expression, bisretinoid reduction, and a manageable safety profile, supporting the program's best-in-class potential.

About 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 (IRD). The company's lead program is evaluating ATSN-201 in a pivotal clinical trial for X-linked retinoschisis (XLRS). Its pipeline also includes gene therapy programs for Usher Syndrome Type 1B, Stargardt disease, and three other undisclosed IRD targets, as well as ATSN-101 for Leber congenital amaurosis type 1 (LCA1), which is advancing in late-stage development in collaboration with Nippon Shinyaku Co., Ltd. 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, visit atsenatx.com.

Investor and Media Contact:
Argot Partners | atsena@argotpartners.com

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