Preclinical Efficacy And Safety Evaluation of AAV‐OTOF in DFNB9 Mouse Model And Nonhuman Primate

Abstract

OTOF mutations are the principal causes of auditory neuropathy. There are reports on Otof‐related gene therapy in mice, but there is no preclinical research on the drug evaluations. Here, Anc80L65 and the mouse hair cell‐specific Myo15 promoter (mMyo15) are used to selectively and effectively deliver human OTOF to hair cells in mice and nonhuman primates to evaluate the efficacy and safety of OTOF gene therapy drugs. A new dual‐AAV‐OTOF‐hybrid strategy to transfer full‐length OTOF is generated, which can stably restore hearing in adult OTOFp.Q939*/Q939* mice with profound deafness, with the longest duration being at least 150 days, and the best therapeutic effect without difference in hearing from wild‐type mice. An AAV microinjection method into the cochlea of cynomolgus monkeys without hearing impairment is further established and found the OTOF can be safely and effectively driven by the mMyo15 promoter in hair cells. In addition, the therapeutic dose of AAV drugs has no impact on normal hearing and does not cause significant systemic toxicity both in mouse and nonhuman primates. In summary, this study develops a potential gene therapy strategy for DFNB9 patients in the clinic and provides complete, standardized, and systematic research data for clinical research and application.

Advancements and future prospects of adeno-associated virus-mediated gene therapy for sensorineural hearing loss

“…Specifically, the hearing of treated mice was restored to nearly WT mice level at least 6 months, and IHCs reinstated the release of synaptic vesicles ( Tang et al, 2023 ). Qi et al (2023) pioneered a novel dual-AAV-OTOF-hybrid approach for delivering full-length OTOF, successfully restoring stable hearing in adult Otof p.Q939*/Q939* mice suffering from profound deafness. Furthermore, they evaluated the transduction efficiency and safety of dual-AAV-OTOF in nonhuman primates (NHPs), providing crucial systematic research data to advance clinical investigations for DFNB9 patients ( Qi et al, 2023 ).…”

“… Qi et al (2023) pioneered a novel dual-AAV-OTOF-hybrid approach for delivering full-length OTOF, successfully restoring stable hearing in adult Otof p.Q939*/Q939* mice suffering from profound deafness. Furthermore, they evaluated the transduction efficiency and safety of dual-AAV-OTOF in nonhuman primates (NHPs), providing crucial systematic research data to advance clinical investigations for DFNB9 patients ( Qi et al, 2023 ). Based on these studies, clinical trials for dual-AAV-mediated gene therapy targeting OTOF have commenced.…”

Data_Sheet_1.XLSX

“…When present in the same cell, the two vectors reconstitute a functional OTOF gene cassette for expressing full-length OTOF protein isoform 5. While this dual vector technique has been shown to restore hearing in OTOFdeficient mice (Akil et al, 2019;Al-Moyed et al, 2019;Qi et al, 2023;Zhang et al, 2023), little is known about the dynamics of dual vector recombination. An understanding of these kinetics will enable a better understanding for the timing of recovery of hearing in human patients treated with dual vector AAV-based gene therapy and for the kinetics of dual vector recombination therapy in general.…”

“…While use of this promoter may provide therapeutic benefit, it adds complication for answering questions regarding dual vector recombination due to lack of Myo15 expression in publicly available cell lines. Additionally, while a dual vector recombination strategy recovers hearing thresholds in mouse studies (Akil et al, 2019;Al-Moyed et al, 2019;Qi et al, 2023;Zhang et al, 2023), potential variability due to surgical delivery to the inner ear, make determining recombined RNA and protein kinetics challenging for in vivo dosed samples.…”

Data_Sheet_4.XLSX

“…Recently, promising work demonstrated recovery of hearing in a mouse model of otoferlin deficiency using AAV-based gene therapy (Akil et al, 2019;Al-Moyed et al, 2019;Qi et al, 2023;Zhang et al, 2023), suggesting the potential of gene therapy in DFNB9 patients.…”