Before reaching human clinical trials, the development of gene therapy for Retinitis Punctata Albescens (RPA) relied heavily on successful preclinical studies in animal models. Research utilizing Rlbp1 knockout mice has been instrumental in demonstrating the potential of AAV-mediated gene replacement to restore visual function.
In these studies, researchers designed an adeno-associated viral (AAV) vector, specifically AAV8, to deliver a functional copy of the human RLBP1 gene. The vector utilized a short RLBP1 promoter to restrict gene expression specifically to the retinal pigment epithelium (RPE) and Müller cells, the natural sites of CRALBP expression. This targeted approach was crucial to avoid aberrant expression in photoreceptors, which could interfere with normal visual processes.
Following subretinal injection of the scAAV8-pRLBP1(short)-hRLBP1 vector, the treated mice exhibited a significant, dose-dependent improvement in the rate of dark adaptation. Electroretinogram (ERG) recordings showed that within 1 to 3 months post-injection, the rate of dark adaptation returned to normal or near-normal levels. Remarkably, this improvement persisted for at least 50 weeks after a single injection.
These preclinical findings provided the necessary proof-of-concept that restoring CRALBP function can correct the visual cycle defects associated with RLBP1 mutations. The success in mouse models directly supported the initiation of the current Phase 1/2 clinical trials, offering a promising therapeutic avenue for patients with RPA.
Medical Disclaimer: This information is for educational purposes only and does not constitute medical advice. Genetic testing and clinical management should be performed by qualified healthcare professionals.