Preclinical evaluation of the efficacy and safety of AAV1-hOTOF in mice and nonhuman primates.

Pathogenic mutations in the gene cause autosomal recessive hearing loss (DFNB9), one of the most common forms of auditory neuropathy. There is no biological treatment for DFNB9. Here, we designed an gene therapy agent by dual-adeno-associated virus 1 (AAV1) carrying human coding sequences with the expression driven by the hair cell-specific promoter , AAV1-hOTOF. To develop a clinical application of AAV1-hOTOF gene therapy, we evaluated its efficacy and safety in animal models using pharmacodynamics, behavior, and histopathology. AAV1-hOTOF inner ear delivery significantly improved hearing in mice without affecting normal hearing in wild-type mice. AAV1 was predominately distributed to the cochlea, although it was detected in other organs such as the CNS and the liver, and no obvious toxic effects of AAV1-hOTOF were observed in mice. To further evaluate the safety of promoter-driven AAV1-transgene, AAV1-GFP was delivered into the inner ear of via the round window membrane. AAV1-GFP transduced 60%-94% of the inner hair cells along the cochlear turns. AAV1-GFP was detected in isolated organs and no significant adverse effects were detected. These results suggest that AAV1-hOTOF is well tolerated and effective in animals, providing critical support for its clinical translation.