Regeneron Pharmaceuticals announced preliminary, positive safety, and efficacy results from the first patient (<2 years of age) dosed in the Phase 1/2 CHORD trial investigating otoferlin gene therapy (DB-OTO) in children with profound genetic hearing loss due to mutations of the otoferlin gene.

“The children who are being enrolled in CHORD are often born with profound hearing loss due to mutations in a single gene, otoferlin, which essentially turns off their auditory circuits,” says Professor Manohar Bance, MB, an ear surgeon and principal trial investigator at Cambridge University Hospitals NHS Foundation Trust in the United Kingdom. “Cochlear implants are the current standard of care but are unable to replicate the full complexity and range of sound. With these very preliminary DB-OTO results, we now have encouraging evidence that this gene therapy may be able to help turn these auditory circuits back on. We look forward to following this child and others further to determine if DB-OTO gene therapy can restore clinically meaningful hearing as they are learning to interact with the world.”

In the trial, the child received an intracochlear injection of DB-OTO in one ear. At planned follow-ups, the child experienced improvements in auditory responses through week six compared to baseline, per auditory brainstem response (ABR) and behavioral (pure tone) audiometry. ABR, a clinically accepted physiologic measure of hearing sensitivity, is often absent in those with classic otoferlin-related hearing loss and was absent in both ears of the child at baseline. There were no concerning safety signals through week six following treatment.

Further reading: Regeneron Adds Hearing Loss Gene Therapy Program Via Decibel Therapeutics Acquisition

Congenital hearing loss (hearing loss present at birth) is a significant unmet medical need with no approved pharmacologic treatment options that affects approximately 1.7 out of every 1,000 children born in the U.S. While hearing loss caused by mutations of the otoferlin gene is ultra-rare, the majority of permanent, congenital hearing loss cases diagnosed in developed countries are sensorineural and result from a single gene defect, making them suitable targets for gene therapy.

“These preliminary DB-OTO results provide early and encouraging proof-of-concept for the treatment of otoferlin-related hearing loss, as well as our pipeline of gene therapies to address more common forms of genetic hearing loss and other therapeutic areas,” says Christos Kyratsous, PhD, senior VP of Research and co-head of Genetic Medicines at Regeneron. “The ongoing CHORD trial is our first clinical-stage auditory program, and we are incredibly grateful to the investigators and the family of this child for embarking on this breakthrough trial. We remain committed to advancing this research and hope these results mean that children with genetic hearing loss will eventually be able to benefit from the revolutionary promise of gene therapies like DB-OTO.”

DB-OTO was originally developed under a collaboration between Regeneron and Decibel Therapeutics that was initially established in 2017, with an extension announced in 2021. In September 2023, Regeneron acquired Decibel Therapeutics, cementing this long-standing collaboration. In addition to the DB-OTO development program, other clinical efforts include AAV.103 for people with GJB2-related hearing loss and AAV.104 for people with stereocilin (STRC)-related hearing loss.

The potential use of DB-OTO for otoferlin-related hearing loss is currently under clinical development, and its safety and efficacy have not been evaluated by any regulatory authority.

The CHORD Trial

The CHORD trial (NCT# 05788536) is a Phase 1/2 first-in-human, multicenter, open-label trial to evaluate the safety, tolerability, and preliminary efficacy of DB-OTO in pediatric patients with otoferlin mutations.

Currently enrolling children across sites in the U.S., United Kingdom and Spain (<18 years of age; staggered by age in the U.S.), CHORD is being conducted in two parts. In the initial dose-escalation cohort (Part A), patients will receive a single intracochlear injection of DB-OTO in one ear, while in expansion cohort (Part B), patients will receive single intracochlear injections of DB-OTO in both ears at the selected dose from Part A.

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