Childhood deafness: gene therapy could regenerate hearing without cochlear implants

A gene therapy, still in the experimental and initial testing phase, to inoculate children who have been deaf since birth with the missing gene, otoferlin, and thus create an alternative to the only solution possible today: the cochlear prosthesis. A team of British, American and Spanish experts has been working on the gene therapy for some time, with results described as 'encouraging' by Manhoar Bance of Cambridge University, head of the team, and one of the seven international speakers at the 40th congress of the Italian Society of Audiology in Bari from 12 to 15 November (around 800 attendees), chaired by Nicola Quaranta, director of the Otorhinolaryngology Unit of the Bari polyclinic.

With gene therapy, administered in the first 48-96 weeks of a child's life who is deaf from birth, the missing gene is carried by a virus injected with a micro-needle into the inner ear. The virus thus infects the non-functioning cells with a functioning gene, restoring hearing in 50-60% of cases. When this trial - envisaged in the Chord project - began, there was no precedent, except for the start of a similar study in China. Having started the experimental treatment on one small patient, "everything worked well," said Bance, citing the case of one of the 12 girls worldwide undergoing the experimental treatment. And the results of the first trial were published in this weeks New England Journal. Three other trials are ongoing: one in China and two in the EU.

"We are still in phase 1," Bance said, "but we are encouraged to move forward. Approximately 70 per cent of the children treated with this therapy have had a recovery that has allowed them to have useful hearing and to develop or begin language development". Some aspects remain to be defined and worked on: how to carry out the genetic test and, above all, how to understand whether there are normal otoacoustic emissions, in which case the patient can, potentially, recover hearing. It will therefore take time,' Bance admitted when speaking to congress participants, 'because the treatment is complicated and could be very expensive, and the reaction of national health systems and pharmaceutical companies remains to be seen. Bance did not say how long it might take for further clinical trials and then commercialisation, but he described this therapy as "the right way to give an answer to genetic deafness sufferers".

 This therapy - conceived for a particular and very rare form of genetic deafness - could, in short, lead the way and thus affect the most common and frequent forms of deafness, which account for 50% of childhood deafness, amounting to an average of 500 cases every year in Italy. In Italy, the only centre authorised for this type of therapy - though it has not treated any children - is the Milan polyclinic, which has been accredited in this international trial. For totally deaf children, the therapy has no contraindications. 'One of the two ears in which it is to be applied is identified,' explains Quaranta, 'and in the other one the standard cochlear implant is applied. Then after six to twelve months, if he can hear again, nothing more is done, otherwise he might undergo a second cochlear implant. So now there is one more hope'. In short, a seed has been planted for the future: working on the DNA.