Oct 18, 2021

Atsena Therapeutics Developing X-Linked Retinoschisis Gene Therapy

Eye On the Cure Research News

The emerging gene therapy is being designed to more safely reach the fovea

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Atsena Therapeutics, a company developing gene therapies for inherited retinal diseases (IRDs), has announced development of a gene therapy for X-linked retinoschisis (XLRS), an IRD characterized by splitting of retinal layers leading to significant vision loss. XLRS is caused by mutations in the gene RS1, which expresses a protein called retinoschsisin that plays a critical role in the maintenance of the retinal structure and cell-to-cell adhesion.

As an X-linked condition, XLRS usually affects males with females as carriers. XLRS is usually diagnosed in boys before the age of 10.

Previous clinical trials for XLRS gene therapies conducted by other groups have not reported significant efficacy. In these trials, the RS1 gene copies were administered by intravitreal injection — i.e., injections into the soft gel in the middle of the eye.

Atsena’s emerging XLRS gene therapy is injected subretinally (underneath the retina). The company says this approach gets the treatment more effectively to the area of the retina where the treatment is needed – i.e., the cavities in the central retina caused by the splitting of retinal layers. The gene therapy uses a specially designed adeno-associated virus delivery system (AAV.SPR) that is able to reach the fragile fovea, the tiny pit in the central retina responsible for visual acuity, without an injection in the foveal region.

“AAV.SPR was born out of a desire to drive therapeutic levels of gene expression in photoreceptors while avoiding the surgical risks of foveal detachment and the immunological complications of intravitreal delivery. The ability to safely and efficiently target foveal cones and to transduce wider expanses of retinal tissue represents a major leap forward in our field,” says Shannon Boye, PhD, co-founder, and director at Atsena and scientist at the University of Florida.

“Dr. Boye and her team are outstanding innovators, leveraging the lessons learned from previous XLRS gene therapy studies to design a better approach and boost chances for success,” says Benjamin Yerxa, PhD, chief executive officer at the Foundation. “This is how good science and therapy development work. Even when trials and experiments fail, we glean new knowledge for moving forward.”

Atsena currently has a Phase 1/2 gene therapy trial underway for Leber congenital amaurosis (LCA1, GUCY2D mutations) and an Usher syndrome type 1B (MYO7A) dual-vector gene therapy in preclinical development.

The RD Fund, the Foundation’s venture philanthropy fund for advancing emerging treatments into and through early stage clinical trials, is a founding investor in Atsena.