Translating Engineered AAV Capsids Into Manufacturable Gene Therapies

By Jacob Smith, Head of Technical Development and CMC Strategy, Viralgen, Sabrina Triffault, Study Director, Preclinical and Clinical Testing, GenoSafe, Laurence Jeanson-Leh, Quality Control Manager, GenoSafe, Jacob Staudhammer, Senior Principal, Dark Horse Consulting Group, and Daniel Lourenco, Senior Consultant, Dark Horse Consulting Group

For more than two decades, AAV development has relied largely on naturally occurring serotypes with established tissue tropism and development experience. However, limitations including high systemic doses, suboptimal targeting, pre-existing immunity, and manufacturing constraints are driving greater use of engineered capsids developed through rational design, directed evolution, and AI-assisted approaches. These next-generation vectors aim to improve tissue specificity and transduction, reduce dosing requirements, and reach difficult targets such as the central nervous system. Yet capsid engineering also introduces new development considerations. Even modest sequence changes can affect upstream productivity, purification, chromatography, filtration, product quality, and impurity profiles. Established manufacturing processes therefore cannot automatically be assumed to perform identically with engineered variants.

Analytical development presents similar challenges, as capsid modifications may affect assay performance, reagent compatibility, identity and potency testing, safety assays, and immunogenicity assessment. In particular, newly engineered capsids may lack appropriate positive controls for antibody and neutralizing antibody assays. Ultimately, manufacturing feasibility, analytical readiness, quality strategy, immunogenicity assessment, and regulatory planning should advance alongside capsid discovery. Established platform knowledge remains valuable, but should be treated as a foundation for evidence-based evaluation and targeted optimization rather than an assumption of compatibility.