An experimental gene therapy has led to durable hearing improvements in patients with an inherited form of deafness, according to a study published on April 22. The research involved correcting mutations in the OTOF gene and showed that 90 percent of recipients experienced improved hearing, with half reaching normal levels after two and a half years.
The findings are significant because they suggest a new treatment option for those affected by genetic forms of deafness, particularly children who are born completely deaf due to OTOF mutations. Early intervention is important as it can affect speech acquisition and cognitive development.
Zheng-Yi Chen, co-senior author of the study and associate professor at Harvard Medical School, said, “How well it worked is really amazing. After 2½ years, more than half of them reached a normal level. They can hear a whisper. At that level, it’s better than mine.”
The international research team included members from Mass Eye and Ear, Harvard Medical School, Fudan University, and other trial sites in China. The therapy involved injecting a neutralized virus carrying a normal copy of the OTOF gene into the inner ear fluid. This allowed production of otoferlin protein in cochlear hair cells and restored the connection between the cochlea and nerves leading to the brain.
Yilai Shu, co-senior author from Fudan University’s Eye and ENT Hospital, said about patient progress: “As follow-up time goes on, these children continue to bring us ongoing surprises. They progress from responding to sounds, to imitating speech, to speaking in short sentences, then to reciting poems and even singing. They always fill us with joy and encouragement.”
The study treated 42 participants aged nine months to 32 years at eight centers across China. While most saw rapid improvement within weeks or months that lasted through two-and-a-half years without serious side effects or toxicity concerns reported by researchers like Chen.
Looking ahead, scientists plan further monitoring over five years while exploring regulatory approval starting in China before expanding elsewhere such as the United States. “We have been working in this field for decades and there was nothing,” Chen said. “Then the treatment came out… now more trials are coming… We’re looking forward to what the future will bring for patients.”
