Preclinical evaluation of AAV2 anti-VEGF gene therapy using scFv for choroidal neovascularization

Single-chain variable fragments (scFvs) have been proposed as efficient therapeutic cargoes for gene therapy. However, their safety and efficacy in clinical settings remain to be fully established. In this study, we constructed a recombinant adeno-associated virus 2 (AAV2) vector encoding an anti-VEGF scFv to inhibit choroidal neovascularization (CNV), and evaluated its efficacy, biodistribution, and safety in non-human primates (NHPs) and chinchilla rabbits. Pharmacological studies demonstrated sustained inhibition of neovascularization and vascular leakage both in vivo and in vitro. Pharmacokinetic and biodistribution analyses further showed that a single subretinal injection of AAV2-antiVEGFscFv resulted in prolonged retention of the transgene product in the retina and choroid, with minimal distribution to non-target tissues. These results indicate that AAV2-antiVEGFscFv may provide a safe and durable therapeutic approach for wet age-related macular degeneration (AMD). Collectively, our results support the potential of scFvs as efficient and well-tolerated therapeutic payloads for in vivo gene therapy, with the capacity to overcome key limitations of conventional antibody-based therapies.