New Hope for Hereditary Deafness: Latest Results

(Posted on Thursday, June 27, 2024)

Approximately 430 million people live with disabling hearing loss, and 26 million individuals are affected by congenital hearing loss, with 60% of cases attributed to genetic factors. Given the large number of people affected by this type of hearing loss, the recent success in treating baby Opal Sandy with gene therapy has brought attention to this promising treatment for hereditary deafness. This new approach provides hope for individuals without positive results from traditional interventions. There is now compelling evidence that we can successfully treat both ears with this gene therapy.

Understanding Binaural Gene Therapy

Binaural adeno-associated virus gene therapy is an advanced method for treating genetic mutations that cause hearing loss. This therapy uses a viral vector to deliver a healthy gene directly to the cochlea’s inner hair cells. The goal is to stimulate the production of essential proteins, such as otoferlin, necessary for normal auditory function.

Initial studies with treatment in one ear showed promising results, leading to the current focus on treating both ears. This approach helps improve hearing in both ears, enhancing overall auditory perception and speech recognition.

This new study is significant because it applies the same methods to both ears as the CHORD trial, of which baby Opal was a part. The therapy aims to achieve more complete and balanced hearing restoration by targeting both ears simultaneously. Its effectiveness has been thoroughly tested in children with autosomal recessive deafness, a type of hereditary deafness caused by mutations in the otoferlin gene.

Restoration of Hearing

One of the most promising results is the improvement in hearing observed in all five patients. Initially, all patients had an average auditory brainstem response (ABR) threshold of over 95 decibels (dB) in both ears. After treatment, significant improvements were recorded.

After 26 weeks of treatment, one patient’s average auditory brainstem response threshold improved to 58 dB in both ears, while another showed improvement to 75 dB in the right ear and 85 dB in the left ear. Similar positive outcomes were observed in other patients, confirming the therapy’s effectiveness. In addition to improved hearing, the treatment positively impacted speech perception and sound source localization. All five patients reported significant improvements in their ability to understand speech and identify the direction of sounds, highlighting the comprehensive benefits of the therapy.

Implications for the Future

The success of the binaural adeno-associated gene therapy in these initial trials offers a promising glimpse into the future of treating hereditary deafness. This therapy could be an alternative to cochlear implants for individuals with otoferlin gene mutations. It aims to address the genetic root cause and restore physiological hearing, significantly improving the quality of life for affected individuals.

While the initial results look promising, it’s essential to acknowledge that this field is still in its early stages. Long-term follow-up is needed to confirm the treatment’s effectiveness and monitor for possible side effects. In addition, we need to address challenges such as high treatment costs, ethical considerations, and regulatory hurdles to make this therapy widely accessible.

As research continues and more data becomes available, the future of gene therapy looks increasingly bright, promising transformative changes in how we approach and treat genetic disorders. 

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This story is part of a series on the current progression in Regenerative Medicine. In 1999, I defined regenerative medicine as the collection of interventions that restore tissues and organs damaged by disease, injured by trauma, or worn by time to normal function. I include a full spectrum of chemical, gene, and protein-based medicines, cell-based therapies, and biomechanical interventions that achieve that goal.

In this subseries, we focus specifically on gene therapies. We explore the current treatments and examine the advances poised to transform healthcare. Each article in this collection delves into a different aspect of gene therapy’s role within the larger narrative of Regenerative Medicine. 

To learn more about regenerative medicine, read more stories at www.williamhaseltine.com