A MiniCEP290 gene replacement therapy to treat CEP290-Leber congenital amaurosis (LCA10)

Abstract

Purpose : Leber congenital amaurosis (LCA) is a debilitating eye disorder and is considered one of the most severe forms of retinal degeneration causing severe vision loss at infancy. Mutations in CEP290 (LCA10) are the most frequent cause of LCA and account for > 26% of all cases. Adeno-associated viral (AAV) vectors are currently the most efficient vectors for gene delivery to the retina. However, the CEP290 gene is too large to be packaged into standard AAV vectors, creating a challenge for the development of a LCA10 gene therapy. We designed a mutation-independent gene therapy delivered with an AAV vector to treat LCA10.

Methods : We designed shorter versions of CEP290 (miniCEP290) under photoreceptor-specific promoters that can be delivered using AAV vectors. Cep290-mutant mice (Cep290^rd16) were injected in the subretinal space at postnatal 10 days. Photoreceptor response to light was measured by electroretinography (ERG). Retinal structure and protein trafficking were evaluated by immunofluorescence using specific marker antibodies.

Results : After demonstrating the efficiency of a CEP290 minigene [CEP290 amino acid 580-1180 domain] under the control of a ubiquitous promoter to enhance function and survival of photoreceptors in neonatal Cep290^rd16 only until 5 weeks of age, this current study ‘s goal was to improve the efficacy of the miniCEP290 approach and optimize protein expression. We show that the expression of CEP290-580-1180 under the control of the rhodopsin kinase promoter improved the ERG response for both rod and cone photoreceptors by ~1.5 folds. Further, modification of the miniCEP290 gene construct with different CEP290 domains improved the photoreceptor structural and functional rescue by ~500% in the Cep290^rd16 mice. We also show that the expression of the new miniCEP290 prolonged the survival and improved the protein trafficking defects, in transduced photoreceptors.

Conclusions : Our preliminary results indicate that miniCEP290 approach with conventional AAV vectors may have the potential for mutation-independent gene therapy in LCA10 patients. These studies may also pave the way to develop new minigene therapies for retinal degenerative diseases caused by mutations in other large genes including Stargardt disease and Usher Syndrome, which are not currently amenable to treatment using conventional AAVs.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.