Gene Treatment Could Cure Hearing Loss

Seeking to dominate the gene therapy field, global healthcare heavyweight, Novartis, has received approval to commence human testing on patients with partial or total hearing loss due to inner ear trauma. Dr. Lawrence Lustig, Columbia University professor and chair of the Department of Otolaryngology, has begun recruiting patients for the Novartis-sponsored clinical trial to identify whether or not his ATOH1 gene therapy will work to restore lost hearing in the human ear.

“If we could re-grow the hair cells of the inner ear of humans, there's no question that the hearing would be better than it would be with an implant,” Lustig says.

ATOH1, also commonly known as Math1, is responsible for stimulating the development of hair cells in embryos.

While there are other initiatives underway to cure deafness caused by genetic mutations at birth, Dr. Lustig’s goal is to restore hearing to patients who have lost their hearing from years of overexposure to high decibel sounds or habitual drug use. Trauma to the inner ear can cause varying degrees of hearing loss, and Lustig expects to see drastic improvement across patients in his latest clinical trial.

The highly-anticipated trial marks the second round of Novartis’ ATOH1 gene therapy testing in humans. These clinical trials target the treatment of disabling hearing loss, a condition that affects 360 million individuals globally and about a third of people over 65. Lustig’s course of treatment stems from promising clinical studies conducted on lab animals.

In 2003, a US-Japanese team out of Ann Arbor, Michigan, was able to improve hearing in Guinea pigs with damaged inner-ear hair cells by up to 80%. The team applied a harmless, lab-engineered virus containing the ATOH1 gene into the cells lining the scala media, the chamber of the cochlea containing the hair cells.

By using sensory electrodes positioned around the animals’ heads, the researchers were able to confirm that the treated animals were successfully registering sound. According to Yehoash Raphael, professor at The University of Michigan and head of the US-Japanese coalition that conducted the study, the injections worked beyond expectation.

“The recovery of hair cells brought the treated ears to between 50% and 80% of their original hearing thresholds,” stated Raphael. “It’s the first time anyone has biologically repaired the hearing of animals,” he added.

Yehoash’s efforts were duplicated in 2013, when University of Kansas professor Hinrich Staecker conducted similar trials on lab mice with damaged hearing. Once again, ATOH1 was concealed inside a harmless virus and injected into the inner ear of each subject. Within two months, the rodents’ ability to hear had improved by about 20%.

A year later, Staecker, backed by Novartis, received the go-ahead to perform the same trials on humans. To date, 45 individuals have been injected with the same ATOH1 gene/virus pairing under Stacker’s trails. Results are expected in 2017.

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