A gene therapy has restored significant hearing ability in children, teens, and young adults with congenital deafness, a study published in Nature Medicine has revealed.

Adeno-Associated Virus (AAV)-OTOF is a new type of gene therapy that helps some deaf people hear again.

Ten participants aged 1.5 to 23.9 years across five sites in China were treated with a specially engineered AAV vector, designed to deliver functional copies of the OTOF gene. This gene is essential for normal auditory function.

The therapy was reported to be “well tolerated”, with 162 Grade I/II adverse events, most of which were mild. “Decreased neutrophil percentage was the most common event (16 of 162),” the researchers wrote, emphasizing the relative safety of the procedure so far.

Dramatic Improvements in Hearing

The early results are nothing short of remarkable. “All ten participants had at least 6 months of follow-up and improved their pure-tone-average hearing level from baseline 106 ± 9 (mean ± s.d.) to 52 ± 30 decibels (dB),” the study states.

The researchers also noted substantial progress in other auditory measurements:

“The average click auditory brainstem response (ABR) threshold” improved from “101 ± 1 to 48 ± 26 dB”

The “tone-burst ABR threshold” went from “91 ± 4 to 57 ± 19 dB”

And the “auditory steady-state response” showed a reduction from “80 ± 14 to 64 ± 21 dB”

Speed and Predictability of Recovery

The therapeutic effect of the gene therapy appeared rapidly. “Therapeutic effect was rapid, taking 1 month to achieve most of the overall hearing improvement,” the authors observed.

Interestingly, some measurements proved better predictors of long-term outcomes than others. “Click and tone-burst ABR thresholds, but not the auditory steady-state response, reliably predicted the behavioral pure-tone-average thresholds after 4 months (R² = 0.68, 0.73 and 0.17, respectively).”

Age Matters

One of the most significant findings was the age-dependency of the treatment’s effectiveness. “An age-dependent therapeutic effect was observed, with optimal outcomes in 5- to 8-year-olds,” the team reported. This suggests a critical window during which the therapy is most likely to yield dramatic hearing restoration.

While the trial is ongoing, the researchers are optimistic about the future of gene therapy for deafness. They note, “These preliminary results show that AAV-OTOF was safe and well tolerated in patients ranging from toddlerhood to adulthood. The trial remains ongoing and requires extended follow-up to confirm the long-term safety and efficacy.”

Also read: STUDY: Deaf cases in China set to reach 623 million by 2060