A single injection of gene therapy has significantly improved hearing in all ten patients born with a genetic form of deafness, according to a new study. Researchers delivered a working copy of the OTOF gene into the inner ear, with most patients regaining hearing within one month. The treatment, tested in China, proved safe and effective across ages from one to 24.
Researchers from Karolinska Institutet in Sweden, collaborating with institutions in China, treated ten patients aged one to 24 at five hospitals. All had deafness caused by mutations in the OTOF gene, which impairs production of the otoferlin protein needed for sound signal transmission from the inner ear to the brain. The therapy used a synthetic adeno-associated virus to deliver a functional OTOF gene via a single injection through the round window membrane in the cochlea. Published in Nature Medicine, the study reported average hearing improvement from 106 decibels to 52 decibels after six months, with effects starting within one month for most participants. Children, particularly those aged five to eight, showed the strongest gains; a seven-year-old girl regained nearly full hearing and could converse with her mother after four months. Adults also experienced meaningful improvements. Maoli Duan, a consultant at Karolinska Institutet's Department of Clinical Science, Intervention and Technology and a corresponding author, called it a huge step forward. He noted that while smaller Chinese studies had succeeded in children, this was the first to include teenagers and adults. The therapy was well-tolerated, with the main side effect being a temporary decrease in neutrophils; no serious adverse reactions occurred over six to 12 months of follow-up. Funding came from Chinese research programs and Otovia Therapeutics Inc., which developed the therapy.
