Update on Reneneron's Gene Therapy for Hearing Loss

I previously mentioned in my recent video on promising treatments being developed for hearing loss and tinnitus the work of a company called Regeneron who, along with a couple other companies, have been developing a gene therapy for a specific form of inherited hearing loss.

This blog post is an update on that work because Regeneron this month released results of their Phase I/II CHORD study assessing their therapy called DB-OTO and the outcome is exciting.

First let’s provide a little background:

How DB-OTO Works

Some babies are born deaf because they carry mutations in a gene called OTOF. This gene makes a protein called otoferlin, which helps the tiny sensory hair cells in the inner ear send sound signals to the brain. Without it, sound can’t be transmitted — even if the ear itself is healthy.

DB-OTO delivers a healthy copy of the OTOF gene directly into the inner ear using two harmless AAV (adeno-associated virus) carriers. Surgeons place the therapy into the cochlea through a gentle injection during a short ear surgery. Once inside, the virus carriers enter the inner ear hair cells and introduce the new functional OTOF genes, allowing the cells to create normal functional otoferlin proteins. The hope is that the treatment results in enough otoferlin protein production that the hair cell function is restored.

What the New Study Showed

In October 2025, results published in the New England Journal of Medicine showed that DB-OTO restored meaningful hearing in most of the children treated. Out of 12 participants, nine could hear much softer sounds than before, and several even reached normal hearing levels. The improvements began within weeks and continued over time. Side effects were generally mild and temporary.

Fast-Track Support from the FDA

The U.S. Food and Drug Administration recognized DB-OTO’s potential by granting Regeneron a special priority review voucher, allowing a much faster evaluation once the company submits its final data. This could shorten approval time by months, meaning the therapy may reach children sooner.

Who Could Benefit

OTOF-related hearing loss is rare — affecting an estimated 20 to 50 babies a year in the U.S., and perhaps hundreds worldwide — but for these families, DB-OTO could be life-changing. As newborn genetic testing becomes more common, more children will be identified early enough to benefit. This therapy would be considered as an alternative to cochlear implantation among this population.

A Glimpse Into the Future

This therapeutic approach marks the first time gene therapy has been shown to restore hearing rather than just assist it. It opens the door to treating other inherited forms of deafness and perhaps even some inner-ear conditions linked to tinnitus. For the hearing-loss community, this is more than medical progress — it’s the beginning of a new era of hearing restoration. It should be acknowledged that a few other companies are working on a similar therapy including Akuous (owned by Eli Lily), Sensorion, and Refreshgene therapeutics but Regeneron is the first one to reach FDA review. I’m excited to see what inner ear conditions will be targeted next with similar approaches.