Two years ago, scientists made history with a gene therapy that restored hearing for a small group of children who had been born deaf, allowing some of them to hear for the first time. Indistinct murmurs turned into audible whispers. The robust gains and lack of safety concerns led the Food and Drug Administration to approve Regeneron’s Otarmeni therapy in April for the small group of people with this rare genetic mutation.

“[Otoferlin-related mutations] are more of a Goldilocks. The ear stays completely intact in animal models, even into geriatric models,” said Joe Burns, former senior vice president of research at Decibel Therapeutics, which was acquired by Regeneron in 2023.

Scientists are now eyeing other hearing-loss targets, including the holy grail — the GJB2 gene. Startups in the United States, France, and China are racing to concoct a solution, with Skylark Bio emerging from stealth on Tuesday to announce that they have dosed their first patient with a therapy aimed at restoring hearing in a child with a GJB2 mutation.