The experimental therapy focuses on hereditary deafness and one rare condition only. Genes are responsible for as much as 60% of deafness and hearing loss in children.
Gene therapy has allowed several children born with inherited deafness to hear.
Researchers observed the children for about six months. They don’t know why the treatment didn’t work in one of them. But the five others, who previously had complete deafness, can now hear a regular conversation and talk with others. Chen estimates they now hear at a level around 60% to 70% of normal. The therapy caused no major side effects.
Preliminary results from other research have been just as positive. New York’s Regeneron Pharmaceuticals announced in October that a child under 2 in a study they sponsored with Decibel Therapeutics showed improvements six weeks after gene therapy. The Philadelphia hospital — one of several sites in a test sponsored by a subsidiary of Eli Lilly called Akouos — reported that their patient, Aissam Dam of Spain, heard sounds for the first time after being treated in October. Though they are muffled like he’s wearing foam earplugs, he’s now able to hear his father’s voice and cars on the road, said Dr. John Germiller, who led the research in Philadelphia.
“It was a dramatic improvement,” Germiller said. “His hearing is improved from a state of complete and profound deafness with no sound at all to the level of mild to moderate hearing loss, which you can say is a mild disability. And that’s very exciting for us and for everyone. ”
Columbia University’s Dr. Lawrence Lustig, who is involved in the Regeneron trial, said although the children in these studies don’t wind up with perfect hearing, “even a moderate hearing loss recovery in these kids is pretty astounding.”
Still, he added, many questions remain, such as how long the therapies will last and whether hearing will continue to improve in the kids.
Also, some people consider gene therapy for deafness ethically problematic. Teresa Blankmeyer Burke, a deaf philosophy professor and bioethicist at Gallaudet University, said in an email that there’s no consensus about the need for gene therapy targeting deafness. She also pointed out that deafness doesn’t cause severe or deadly illness like, for example, sickle cell disease. She said it’s important to engage with deaf community members about prioritization of gene therapy, “particularly as this is perceived by many as potentially an existential threat to the flourishing of signing Deaf communities.”
Meanwhile, researchers said their work is moving forward.
“This is real proof showing gene therapy is working,” Chen said. “It opens up the whole field.”