Regeneron presented results from an ongoing Phase I/II clinical trial for its investigational gene therapy, DB-OTO, at the annual American Society of Gene and Cell Therapy (ASGCT) meeting, being held in Baltimore, Md. from May 7–11.

DB-OTO, a gene therapy for genetic deafness, improved hearing in one child, treated at 11 months old to normal levels within 24 weeks. A second child, treated at 4 years old, also showed hearing improvements at a six-week assessment, according to the company (1). Both children were born with genetic deafness due to variants of the otoferlin gene.

The results are from the ongoing Phase I/II CHORD (NCT# 05788536) first-in-human, multicenter, open-label trial. The trial evaluates the safety, tolerability, and preliminary efficacy of DB-OTO in infants, children, and adolescents with otoferlin (OTOF) variants in the United States, United Kingdom, and Spain. CHORD is a two-part study where participants will receive a single intracochlear injection of DB-OTO in one ear in Part A of the study. In Part B, participants receive simultaneous single intracochlear injections of DB-OTO in both ears at the selected dose from Part A.

Congenital deafness impacts approximately 1.7 out of every 1000 children born in the United States, according to Regeneron (1). Otoferlin-related hearing loss is especially rare and caused by variants in the otoferlin gene, “which impairs the production of the OTOF protein that is critical for the communication between the sensory cells of the inner ear and the auditory nerve.”

Study data presented at ASGCT showsat the 24-week assessment the first participant, a 16-month-old child, had “improvement of hearing to normal levels across key speech frequencies, with an average 84 dB improvement from baseline and one frequency measure reaching 10 dB in hearing level per PTA. Across all tested frequencies, an average 80 dB improvement from baseline was observed.” There was also positive ABR responses, with best frequency reaching 45 dB.

The second participant, a four-year-old child, experienced consistent results to the first participant, including “initial improvement of hearing with responses to loud sounds, which was observed across key speech frequencies, with an average 19 dB improvement from baseline and one frequency measure reaching 80 dB in hearing level per PTA. Across all tested frequencies, an average 16 dB improvement from baseline was observed.” Positive ABR responses had best frequency reaching 75 dB.

“The opportunity of providing the full complexity and spectrum of sound in children born with profound genetic deafness is a phenomenon I did not expect to see in my lifetime,” said Lawrence R. Lustig, MD, chair of Columbia University’s Department of Otolaryngology–Head & Neck Surgery and a clinical trial investigator, in a press release. “These impressive results showcase the revolutionary promise of DB-OTO as a potential treatment for otoferlin-related deafness, and we are excited to see how this translates into an individual’s development, especially [because] early intervention is associated with better outcomes for speech development. With the DB-OTO CHORD trial now enrolling participants in sites across the US and Europe, we’re part of the beginning of a new era of gene therapy research that looks to create treatment options that address the root cause of profound genetic deafness.”

Reference

1. Regeneron. Latest DB-OTO Results Show Dramatically Improved Hearing to Normal Levels in a Child with Profound Genetic Deafness Within 24 Weeks and Initial Hearing Improvements in a Second Child at 6 Weeks. Press Release. May 8, 2024.