New Gene Therapy on the Horizon for Hearing Loss
As lewd and crude and rude as it sounds, it is the general response for the person on the street, even if muttered underneath his or her breath, when dealing with someone—friend, family, co-worker, etc.—who suffers from mild to moderate hearing loss.
Aside from some surgical procedures that are not as commonly known, hearing devices—while being constantly upgraded in the digital age—have been the traditional source of help.
But there is one other ray of hope burgeoning on the horizon: Gene therapy.
From the Ivy League to the University of Miami to the University of Michigan to Oregon State to Tel Aviv, experts are on the verge of cracking the case.
“Although not yet available, inner ear gene therapy for monogenic hearing loss is an emerging technology,” explained Jeffrey R. Holt, PhD, a professor of Otolaryngology & Neurology at Harvard Medical School and of Boston Children’s -Hospital. “There is growing interest from scientists, funding agencies, industry and patients, all spurred on by recent proof-of-concept studies showing recovery of auditory function in animal models of human hearing loss.”
Holt added that genetic treatments for hearing loss sit on the horizon and the significance of this new therapeutic strategy for patients and families is high.
Nonetheless, he cautioned that the most common forms of genetic hearing loss, the result of mutations in GJB2, may be difficult to treat using gene therapy. Other rare forms of genetic hearing loss, due to mutations in OTOF, TMC1, or Usher syndrome, may be those first in line, but others will like follow.
Fan-Gang Zeng, PhD, the director of the Center of Hearing Research at the University of California-Irvine School of Medicine, explained that gene therapy addresses hearing loss biologically by repairing or restoring damaged cells, which hearing aids or cochlear implants do not accomplish.
“Gene therapy is the future, but we don’t know when the future will come,” he said. “While gene therapy is still in infancy, genetic screening of hearing loss is relatively matured. Concurrent screening with traditional audiological measures (OAE and ABR) and genetic testing can improve both the accuracy and prognosis of hearing loss while helping patients and doctors predict its course of development and management on an individual basis.”
Yehoash Raphael, PhD, is a professor of Otolaryngology at the University of Michigan’s Kresge Research Institute. He has been recognized around the globe for his research, the interests of which include inner ear biology, protection and regeneration, gene therapy, genetic deafness, CHARGE Syndrome and stem cell therapy.
Raphael believes gene therapy should be advanced for several clinical conditions, both environmental and genetic.
“At the cellular level, the goals would be related to repair and regeneration of cells that are injured or lost,” he said. “At present, amplification or cochlear implants provide an acceptable solution for many patients.”
He cautioned, however, the biological therapy that restores function may work better, but is not currently available.
“Ideally, we would like gene therapy to improve so it can be used for treating genetic deafness and sensorineural hearing loss caused by hair cell loss due to overstimulation, aminoglycosides, or infections,” he said. “As such, gene therapy presents an exciting prospect for future hearing restoration therapies.”
At Michigan, Raphael and his colleagues are using combinatorial gene transfer methods to enhance the efficiency of new hair cells and are planning to enhance this approach and include other genes.
“We are working on two mouse models for genetic inner ear disease, trying to better understand the biology of the mutation and also to design therapies,” he said, adding that the research on therapies has met with mixed results.
Holt’s lab has focused on development of gene therapy for patients with mutations in TMC1 and for Usher syndrome patients.
“We have remarkable data showing full recovery auditory function in some cases,” he said. “We are working with industry partners to bring these therapies into the clinic.”
Article originally appeared on The Hearing Journal