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On February 25, 2025, at the 48th Annual Meeting of the Association for Research in Otolaryngology (ARO) held in Orlando, Regeneron presented the Phase I/II data of the gene therapy DB-OTO. This treatment partially restored hearing in 10 out of 12 children with severe deafness (otoferlin gene mutation-related deafness), further confirming the preliminary results announced at the American Society of Gene and Cell Therapy Annual Meeting last year, when two children regained their hearing after treatment, drawing widespread attention.Otoferlin is a protein that connects the sensory cells of the inner ear to the auditory nerve leading to the brain. Mutations in otoferlin can disrupt the transmission of external sound signals. When the protein mutates, the signal cannot be transmitted, but the structure of the ear remains intact. The biological characteristics of otoferlin are key to the initial success of this therapy, as mutations in this gene cause deafness without damaging the structure or cells of the ear.DB-OTO was acquired by Regeneron in 2023 for $109 million from its long-term development partner, Decibel Therapeutics.It is a gene therapy candidate based on the dual-vector AAV1, which addresses the issue of the OTOF gene (encoding Otoferlin) being too large for a single AAV vector by segmenting and packaging the OTOF cDNA into two AAV vectors. DB-OTO is administered via intracochlear injection and can be used to restore congenital deafness caused by mutations in the OTOF gene.In the Phase 1/2 CHORD trial, 12 children received DB-OTO treatment, most of whom were under the age of 4, although two participants were already 16 years old at the time of treatment. One ear of nine patients received DB-OTO treatment, while both ears of the other three patients (all approximately 1 year old) were treated.Before the trial, the 10 patients could only hear sounds of approximately 100-120 decibels. Within 12 weeks after the treatment, all these patients showed some degree of improvement. Five of the patients were reassessed at 24 weeks, and three of these five patients were able to hear sounds as low as 40 decibels after the treatment. None of the 12 patients experienced any adverse reactions to the DB-OTO treatment.At least five companies globally have laid out gene therapy strategies targeting otoferlin mutation-related deafness, with Regeneron being one of them. In 2022, Eli Lilly acquired Akuous for $487 million to obtain the company’s treatment solutions for inner ear diseases. Sensorion, headquartered in Montpellier, France, announced positive Phase I/II data for its otoferlin mutation-related deafness gene therapy at the end of last year. Another company based in China, Dingxin Gene, also restored hearing in children with otoferlin mutation-related deafness through gene therapy in 2023.1.https://www.biospace.com/drug-development/regenerons-gene-therapy-restores-hearing-in-patients-with-rare-genetic-deafness
