'A landmark moment for the field': FDA approves first-ever gene therapy for inherited deafness

The U.S. Food and Drug Administration (FDA) has approved the first-ever gene therapy for inherited deafness.

The therapy, called Otarmeni, is approved to treat a form of hearing loss caused by mutations in the OTOF gene, which codes for a protein called otoferlin. Cells in the inner ear need otoferlin to translate vibrations into signals that can be interpreted by the brain. When people carry two defective copies of the OTOF gene — one from each parent — this line of communication between the inner ear and brain is cut, resulting in severe-to-profound hearing loss.

Otarmeni is a one-time treatment that uses harmless viruses to deliver working copies of OTOF into the ear. In a trial including 20 participants, 16 showed improved hearing within six months, and one additional person showed improvement within a year of treatment.

Some participants improved to the point that they could hear whispers, while all the participants who responded to the therapy reached a level of hearing that does not typically require cochlear implantation — meaning the use of a device to bypass the inner ear and restore some hearing. Many people with this form of hearing loss get cochlear implants, but the implants don't perfectly replicate natural hearing and require maintenance over time.

Based on the trial results, Otarmeni was approved for both children and adults with OTOF-related hearing loss, the therapy's maker Regeneron announced Thursday (April 23). The company has said that the treatment itself will be free to patients in the U.S., not including out-of-pocket administration costs that might be dictated by a patient's doctor and insurance.

"The FDA approval of this gene therapy is a landmark moment for the field and, most importantly, for patients," said Zheng-Yi Chen, an associate scientist at the Eaton-Peabody Laboratories at Mass Eye and Ear and an associate professor at Harvard Medical School. Chen has been involved in a trial of a similar gene therapy for OTOF-related deafness in China.

Chen said the data from the trial "convincingly demonstrate both safety and efficacy." The approval process was very fast, he added, taking less than three years from when the first patient was dosed in 2023. (Otarmeni was approved through a special FDA "fast track" process, in part because there were no existing treatments for OTOF-related hearing loss that address its underlying cause.)

The speed "underscores both the robust clinical results and the urgent, unmet medical need for children with OTOF-mediated congenital hearing loss," Chen told Live Science. "We are incredibly encouraged by this milestone, which will serve as a catalyst to accelerate the development of future genetic therapies for hearing loss."

OTOF-related hearing loss affects about 50 newborns per year in the U.S. The new therapy is approved for those with two defective copies of the OTOF gene and no history of using a cochlear implant in the ear intended for treatment. Installing these implants damages the inner ear, so a gene therapy is unlikely to work; but those who have only one cochlear implant can get the gene therapy in the opposite ear.

Patients seeking the therapy must also have intact outer hair cells, which are special cells in the ear that act as amplifiers, increasing the movement of the eardrum in response to sound.

An international trial testing Otarmeni is still ongoing and is recruiting children under 18 in the U.S., United Kingdom, Spain, Germany and Japan.

"I've witnessed firsthand my trial participant responding to their mother’s voice, dancing to music and interacting with the world, and these moments are now possible for more children born with this specific form of hearing loss," Dr. A. Eliot Shearer, an otolaryngologist at Boston Children’s Hospital, associate professor at Harvard Medical School and trial runner, said in the Regeneron statement.