Gene therapy restores hearing in 5 of 6 deaf children in trial

SHANGHAI – An experimental gene therapy being developed by a Chinese company restored hearing in children with congenital deafness, researchers working on a clinical trial reported on Jan 24, adding to growing evidence of the efficacy of such treatments.

Five of six young children with profound deafness experienced hearing recovery and improvements in speech recognition six months after treatment with the therapy from Refreshgene Therapeutics, according to the report published in medical journal The Lancet.

“The results from this study are truly remarkable. We saw the hearing ability of children improve dramatically week by week, as well as the regaining of their speech,” Dr Zheng-Yi Chen of Mass Eye and Ear, a teaching hospital of Harvard Medical School, who worked on the trial, said in a statement.

All of the children had profound deafness caused by mutations of the OTOF (otoferlin) gene. Functioning otoferlin protein is necessary for the transmission of sound signals from the ear to the brain.

OTOF mutations account for two per cent to eight per cent of cases of congenital deafness, earlier research suggests. One out of every 1,000 children born in the United States has moderate to profound hearing loss.

In surgical procedures performed at the Eye & ENT Hospital of Fudan University in Shanghai, researchers used a harmless virus to carry a version of the human OTOF gene into patients’ inner ears.

After 26 weeks, five of the six children demonstrated hearing recovery, with dramatic improvements in speech perception and the ability to conduct conversation, the researchers reported.

Most side effects were minor and none had long-term impact, they said.

The researchers are not sure why the sixth child did not respond. One possible explanation is that some of the gene therapy solution leaked from the inner ear during or after surgery.

Refreshgene is also working with OBio Technology Shanghai on a gene therapy for the eye disease neovascular age-related macular degeneration.

On Jan 23, a separate team of researchers announced hearing restoration in an 11-year-old who was the first patient to receive pharmaceutical company Eli Lilly’s OTOF gene therapy.

In October 2023, Regeneron Pharmaceuticals announced positive safety and efficacy results in the first child with profound OTOF-related hearing loss to receive its otoferlin gene therapy.

Updated results from these trials will be presented at the Association for Research in Otolaryngology’s mid-winter meeting in February.

“Not since cochlear implants were invented 60 years ago has there been an effective treatment for deafness,” said Dr Chen. “This is a huge milestone that symbolises a new era in the fight against all types of hearing loss.”

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