A cutting-edge technique, trialled by Fudan University in Shanghai in collaboration with the Massachusetts Eye and Ear hospital in Boston, has been proposed for children with hearing problems. A specially-modified virus was used to “transport” to the unhealthy cells inside the ear the genetic material required to return those cells to normal.
Gene therapy could become one of the options offered to the parents of children suffering from profound deafness of an hereditary nature, in particular the type caused by the mutation of a gene called OTOF, which encodes a protein (otoferlin) crucial for the transmission of auditory stimuli from the ear to the brain.
Over the course of just a few weeks, the results of a number of studies have come out that prove it is possible to correct the defective gene using a safe technique, one that can at least partially restore hearing to nearly all of the children on which it was trialled.
The last, chronologically speaking, was a study published in the Lancet scientific journal, in which paediatricians and audiologists from Fudan University in Shanghai (China), in collaboration with their colleagues from the Massachusetts Eye and Ear hospital in Boston (United States), trialled the therapy on six children, chosen from an initial sample group of 425. Using a specially modified adenovirus (similar to those that cause the common cold) the researchers were able to insert into the unhealthy cells in the ear a segment of DNA capable of restoring those cells’ normal function.
Deaf children’s hearing restored to 70% capacity
The researchers stayed in touch with their young patients for 26 weeks and were able to verify that all of them, except for one, began to hear, with a dramatic and positive change to their hearing parameters (and, as a result, their ability to recognise sounds and learn to speak). According to the estimates, their hearing capacity now stands at 60–70% that of hearing children, though it still remains unclear why one of the children did not respond to the therapy (efforts are now being made to understand what happened).
As far as side effects are concerned, 48 different ones are possible, but in 96% of cases these are minor and transient. The genetic approach, meanwhile, is state of the art. Until now, attempts to transport the healthy version of the OTOF gene, which is quite large, had failed. However, the adenovirus used by the Chinese and U.S. researchers was “dual”, meaning, to put it very simply, that it was able to carry the OTOF gene in two pieces.
Additional trials to solve deafness in children also meeting with success
While the researchers are making plans to continue the above trials on a larger sample group, while also extending the follow-up time for the children, an article in TIME magazine, which shines a light on various ongoing studies, has published the outcomes achieved with another two children in China. Lastly, just a few days ago, the Children's Hospital of Philadelphia made public the successful treatment of its first such patient, an 11-year-old boy.
What’s more, over the last few months, there have been other signs pointing in this direction. For instance, in October, the Regeneron Pharmaceuticals company, together with Decibel Therapeutics, announced that it had provided the gene therapy needed to successfully treat a child younger than two years of age. The number of young patients treated using a genetic approach is therefore growing, and the hope is that a sufficient number of cases may soon be reached to request approval from public health authorities, such as the U.S. Food and Drug Administration (FDA) or the European Medicines Agency (EMA).
According to some estimates, 34 million children around the world suffer from profound deafness, which, in six out of ten cases, is congenital.
