Several children born with a rare, inherited form of deafness can now hear thanks to two new gene therapies, clinical trial results show.
Both therapies target the gene for otoferlin, a protein in the inner ear that lets nerve cells translate vibrations from sound into electrical signals that can be interpreted by the brain. Mutations in the otoferlin gene cause about 1% to 8% of cases of congenital deafness, in which a child is born deaf. Still, mutations in the gene are fairly rare, affecting an estimated 200,000 people worldwide.
The new gene therapies use harmless, modified viruses to deliver working otoferlin genes directly into the inner ear. Early data suggest that the treatments work for most patients — although much more research is needed to get the therapies fully approved.
“The results from this study are truly remarkable,” Zheng-Yi Chen, an associate scientist at the Eaton-Peabody Laboratories at Mass Eye and Ear and an associate professor at Harvard Medical School, said in a statement. “We saw the hearing ability of children improve dramatically week by week,” said Chen, who is involved in one of the trials.
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Chen and colleagues’ trial results were published Wednesday (Jan. 24) in the journal The Lancet. They will also be presented Feb. 3 at the annual meeting of the Association for Research in Otolaryngology (ARO).
The trial included six children who were treated at a hospital affiliated with Fudan University in Shanghai. All of the kids had two mutant copies of the otoferlin gene, and they had complete hearing loss prior to treatment. They ranged from 1 to 6 years old.
The gene therapy they received contained adeno-associated viruses — a type of virus often used for gene therapy — whose genes had been scooped out and replaced with the otoferlin gene. Because of the otoferlin gene’s large size, though, the scientists actually split its genetic material in half, placing each half in its own viral vessel. The researchers had previously tested the safety and effectiveness of this treatment in animals, including mice and nonhuman primates.
During the trial, each child had the gene therapy injected into one ear, through a membrane that separates the middle ear from the inner ear. All but one of the children showed “robust hearing recovery” within 26 weeks. These hearing improvements began to appear about four to six weeks post-treatment,…
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