Gene therapy can restore hearing function in children suffering from hereditary deafness, new research from the US and China has found.
The research team found the novel gene therapy to be an effective treatment for patients with a specific form of autosomal recessive deafness.
This was the first human clinical trial to administer gene therapy for treating this condition, with the most patients treated and longest follow-up to date.
Zheng-Yi Chen, DPhil is an associate scientist in the Eaton-Peabody Laboratories at Mass Eye and Ear and associate professor of Otolaryngology–Head and Neck Surgery at Harvard Medical School.
The researcher said: “If children are unable to hear, their brains can develop abnormally without intervention.
“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.”
DFNB9 is a hereditary condition caused by mutations of the OTOF gene and a failure to produce a functioning otoferlin protein, which is necessary for the transmission of the sound signals from the ear to the brain.
There are currently no FDA-approved drugs to treat hereditary deafness, which has opened the door for new solutions like gene therapies.
In order to test the novel treatment, six children with DFNB9 were observed over a 26-week period at the Eye & ENT Hospital of Fudan University.
The Mass Eye and Ear collaborators utilised an adeno-associated virus (AAV) carrying a version of the human OTOF gene to carefully introduce the gene into the inner ears of the patients through a special surgical procedure.
Differing doses of the single injection of the viral vector were used in the study.
All six of the children in the study had total deafness, as indicated by an average auditory brainstem response (ABR) threshold of over 95 decibels.
After 26 weeks, five children showed hearing recovery, showing a 40-57 decibel reduction in ABR testing, dramatic improvements in speech perception and the restored ability to conduct normal conversation.
At follow-up, 48 adverse events were observed, with a significant majority (96 per cent) being low grade, and the rest being transitory with no long-term impact.
The study was led by Yilai Shu, MD of the Eye & ENT Hospital of Fudan University at Fudan University.
The researcher said: “We are the first to initiate the clinical trial of OTOF gene therapy.
“It is thrilling that our team translated the work from basic research in animal model of DFNB9 to hearing restoration in children with DFNB9.
“I am truly excited about our future work on other forms of genetic hearing loss to bring treatments to more patients.”
The research team plans to expand the trial to a larger sample size as well as track their outcomes over a longer timeline.
Chen said: “Not since cochlear implants were invented 60 years ago, has there been an effective treatment for deafness.
“This is a huge milestone that symbolises a new era in the fight against all types of hearing loss.”
