AAV gene therapy for autosomal recessive deafness 9: a single-arm trial

Gene therapy for congenital deafness has shown promising results in children but lacks data in older populations. We conducted a single-arm trial of adeno-associated virus (AAV)-OTOF gene therapy using the Anc80L65 capsid in ten participants with autosomal recessive deafness 9 aged 1.5 to 23.9 years at five sites in China. The primary endpoints were safety and tolerability within 5 years, and secondary endpoints assessed auditory function. Initial findings from the ten patients with 6–12 months of follow-up, including one patient who received two injections, revealed that the therapy was well tolerated, with 162 grade I/II adverse events. Decreased neutrophil percentage was the most common event (16 of 162). All ten participants had at least 6 months of follow-up and improved their pure-tone-average hearing level from baseline 106 ± 9 (mean ± s.d.) to 52 ± 30 decibels (dB). Other secondary endpoints showed similar improvements, including the average click auditory brainstem response (ABR) threshold, the tone-burst ABR threshold and the auditory steady-state response (101 ± 1 to 48 ± 26 dB, 91 ± 4 to 57 ± 19 dB and 80 ± 14 to 64 ± 21 dB, respectively). Post hoc analyses were conducted to evaluate the timecourse and factors contributing to the hearing improvement. Therapeutic effect was rapid, taking 1 month to achieve most of the overall hearing improvement. On an individual level, click and tone-burst ABR thresholds, but not the auditory steady-state response, reliably predicted the behavioral pure-tone-average thresholds after 4 months (R² = 0.68, 0.73 and 0.17, respectively). An age-dependent therapeutic effect was observed, with optimal outcomes in 5- to 8-year-olds. These preliminary results show that AAV-OTOF was safe and well tolerated in patients ranging from toddlerhood to adulthood. The trial remains ongoing and requires extended follow-up to confirm the long-term safety and efficacy. ClinicalTrials.gov registration: NCT05901480.