Rationally designed chimeric AAV capsids demonstrate reduced liver tropism and enhanced muscle transduction in both rodents and non-human primates

Background & Aim: Recombinant adeno-associated viral (rAAV) vectors have emerged as essential tools for gene delivery in therapeutic applications. However, their clinical efficacy is often hindered by insufficient tissue-specific transduction and undesirable off-target effects, particularly liver toxicity. To address these issues, we developed a two-step AAV capsid engineering strategy aimed at reducing liver tropism and enhancing target-specific transduction. Methodology: To evaluate PG007’s therapeutic potential, we compared its performance to AAV9, which is under clinical investigation for Duchenne muscular dystrophy (DMD). Systemic administration of a micro-dystrophin gene (2E+13 vg/kg) in dystrophin-deficient (DMD-KO) mice showed that PG007 significantly improved muscle strength, reduced CK and AST levels, and lowered liver and muscle damage compared to AAV9. PG007-treated mice also exhibited broader micro-dystrophin expression in muscles and lower off-target transduction in the liver and kidney. Results: Immunofluorescence confirmed enhanced dystrophin restoration in skeletal and cardiac muscles of PG007-treated mice. Over a 10-month period, PG007 increased survival rates significantly compared to both AAV9 and vehicle-treated controls. Conclusion: Our study underscores PG007's therapeutic efficacy and its potential as a next-generation capsid for muscle-targeted gene therapy. Additionally, AAV.Zero1 and AAV.Zero3 serve as versatile backbones for tissue-specific targeting. The π-Icosa serotype screening platform provides a robust pipeline for the rapid development of optimized AAV vectors across various tissues and species, accelerating human gene therapy advancements.