DEAF-INITELY A BREAKTHROUGH: Hearing restored by single injection in just weeks, study finds

Diane Joy Galos

A single injection may now be all it takes to turn up the volume on life—literally.

Researchers from Karolinska Institute, along with several Chinese institutions, reported that a single gene therapy injection helped restore hearing in children and adults born with congenital deafness or severe hearing loss.

All ten patients involved in the study showed improved hearing, and the treatment was found to be safe and well-tolerated.

The research was a collaboration between institutions in Sweden and China and was published in Nature Medicine.

"This is a huge step forward in the genetic treatment of deafness, one that can be life-changing for children and adults," said Maoli Duan, a consultant and docent at Karolinska Institutet and co-author of the study.

The study included ten participants aged 1 to 24 years, all of whom had hearing loss caused by mutations in the OTOF gene. These mutations prevented the production of otoferlin, a protein necessary for sending sound signals from the ear to the brain.

Researchers used a synthetic adeno-associated virus (AAV) to deliver a working copy of the OTOF gene into the inner ear through a one-time injection.

The injection was administered through the round window, a membrane at the base of the cochlea. Most patients showed some hearing recovery within a month of receiving the treatment.

By six months, all participants showed marked improvement, with the average level of hearing improving from 106 decibels to 52 decibels. Children responded especially well, particularly those between ages five and eight.

"Smaller studies in China have previously shown positive results in children, but this is the first time that the method has been tested in teenagers and adults, too," said Dr. Duan.

One standout case was a seven-year-old girl who regained nearly full hearing and could chat easily with her mother just four months post-treatment. Despite the therapy working best in younger patients, it also produced positive outcomes for teens and adults.

"Hearing was greatly improved in many of the participants, which can have a profound effect on their quality of life. We will now be following these patients to see how lasting the effect is," he added.

The therapy was generally safe, with no serious side effects reported during the 6 to 12-month follow-up period. The most common minor side effect was a drop in neutrophil levels, a type of white blood cell.

"OTOF is just the beginning," said Dr. Duan.

He explained that they are now expanding research to other common deafness-related genes like GJB2 and TMC1, which are more complex but promising in animal trials.

The study was carried out with partners including Zhongda Hospital, Southeast University in China, and was funded by Chinese research programs and Otovia Therapeutics Inc., the company behind the gene therapy.