Abstract 14481: Engineered Cardiac-Specific AAV Capsids From a Novel Next-Generation Platform (next-CAP) With Cross-Species Selection for Cardiac-Targeted Gene Therapy

Background: Adeno-associated virus (AAV) based gene therapy bears the potential to transform future clinical care of hereditary and acquired heart failure. However, the broadly used AAV9 serotype exhibits fatal liver toxicity in clinical studies and requires long-term immunosuppressive therapy when used systemically e.g., for LAMP2 gene-associated cardiomyopathy.

Hypothesis: AAVs with genetically-engineered cardiac tropism are key for safe and efficient delivery of therapeutic gene replacement, silencing or editing systems to the diseased heart with minimized off-target organ transduction after a simple systemic administration.

Technology & Results: We developed novel cardiac-specific AAV capsids by a next-generation experimental-bioinformatic AAV capsid development platform (next-CAP) employing mouse, farm pig and non-human primate models. A highly diverse capsid library with more than 100 million variants was generated from novel mammalian heart AAV isolates integrating DNA shuffling and peptide display approaches and underwent a two-step cross-species in vivo evolution. Implementing a unique molecular identifier strategy eventually allowed for combined long- and short-term sequencing to capture 77 novel AAV capsid variants displaying highest enrichment in hearts over all other organs, including the liver with superior patterns to AAV9. Subgroups of the top heart-AAV capsid portfolio displayed an overall sequence homology of up to 99.5% identity highlighting the presence of novel cross-species conserved heart-homing motifs. As producibility was another inherent screening criteria, our cardiac-specific AAV capsid portfolio already provides scalable manufacturing characteristics for in vivo indications.

Conclusion: Our proprietary portfolio of novel heart-specific AAV capsids now enables the systematic development of optimal therapeutic capsid-promoter-transgene ensembles for further dose-expression, -efficacy and -toxicity assessments for various hereditary and acquired HF indications in suitable model systems. In summary, we developed an efficient and versatile platform for the generation of next-generation AAV capsids for heart-specific gene therapy of yet uncurable rare and common cardiac diseases.