Gene Therapy Breakthrough Restores Hearing in Children with Rare Deafness: Long-Term Success Confirmed in Clinical Trials

Regeneron Pharmaceuticals has received U.S. Food and Drug Administration approval for Otarmeni™ (lunsotogene parvec-cwha), the first-ever gene therapy for genetic hearing loss, marking a significant milestone in the treatment of inherited deafness.

The therapy is designed to treat children born deaf due to mutations in the OTOF gene, which accounts for between 2 percent and 8 percent of genetic hearing loss cases worldwide. Babies with this mutation are completely deaf at birth, which impairs speech acquisition and can hinder cognitive development if left untreated.

Clinical trial data showed that 90 percent of participants experienced improved hearing after receiving the one-time gene therapy, with half achieving normal hearing levels by the study’s endpoint at 2½ years. Patients aged 18 and younger demonstrated the strongest gains in both hearing ability and speech recognition, while adults also showed improvements, though to a lesser extent.

“How well it worked is really amazing,” said Zheng-Yi Chen, co-senior author of the study and associate professor of otolaryngology-head and neck surgery at Harvard Medical School and Mass Eye and Ear. “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 treatment works by delivering a functional copy of the OTOF gene using a modified viral vector, thereby correcting the underlying genetic defect that prevents proper sound signal transmission from the inner ear to the brain. This approach not only restores auditory function but also supports language development in young children who would otherwise face lifelong communication challenges.

Worldwide, approximately 430 million people live with disabling hearing loss requiring rehabilitation, including 34 million children, according to the World Health Organization. In newborns, about 60 percent of deafness has genetic causes, and while OTOF mutations represent a smaller subset of these cases, researchers believe the platform developed for this therapy can be adapted to target other genes associated with hereditary hearing loss.

Regeneron’s research team is already working to modify the therapy to address mutations in the GJB2 gene, the most common cause of genetic hearing loss, potentially expanding the treatment’s reach to a much larger patient population in the future.

This approval represents the first time a gene therapy has been authorized in the United States to restore a sensory function, opening new possibilities for treating other forms of genetic sensory disorders through similar molecular approaches.