Decibel Therapeutics announced approval of its Clinical Trial Application (CTA) by the Spanish Agency of Medicines and Medical Devices (AEMPS) to initiate a Phase 1/2 clinical trial in pediatric patients of DB-OTO, its lead gene therapy product candidate. DB-OTO is being developed in collaboration with Regeneron Pharmaceuticals, Inc. and is a cell-selective, adeno- associated virus (AAV) gene therapy product candidate designed to provide durable, physiological hearing in individuals with profound, congenital hearing loss caused by mutations of the otoferlin gene. The CTA in Spain is part of an international regulatory strategy for clinical development of DB-OTO, which also includes a regulatory clearance for an Investigational New Drug (IND) application in the United States in October 2022 and a CTA approval by the U.K. Medicines and Healthcare Products Regulatory Agency (MHRA) in January 2023.

Decibel expects that clinical trial participants in the U.K. and Spain will be infants two years of age and younger. The Company anticipates reporting the initial safety and tolerability data and preliminary efficacy data, as measured by ABR, from the first patients in the Phase 1/2 clinical trials in the first quarter of 2024. The Phase 1/2 dose escalation clinical trial, known as CHORD(TM), is designed to evaluate the safety, tolerability and efficacy of DB-OTO in pediatric patients with congenital hearing loss due to an otoferlin deficiency.

In addition to safety and tolerability endpoints, the auditory brainstem response (ABR) -- an objective, clinically accepted, physiologic measure of hearing sensitivity -- will be used as an efficacy endpoint in the clinical trial. The ABR, which was used to characterize dose-response of DB-OTO after intra-cochlear delivery in translational studies in animal models, provides an opportunity to rapidly assess hearing functionality and sensitivity.