Researchers have recently found an enzyme-inhibitor drug that could effectively treat hearing loss induced by chemotherapy drug cisplatin, usually known to cause 70% irreversible damage to cochlear cells.

Researchers have found that inhibiting a new enzyme protects mice and rats from noise or drug-induced hearing loss. The study suggests that CDK2 inhibitors prevent the death of inner ear cells, which has the potential to save the hearing of millions of people around the world. A team of researchers screened over 4,000 drugs for their ability to protect cochlear cells from the chemotherapy agent cisplatin.

Cisplatin is used to treat a variety of cancers but causes irreversible hearing loss in up to 70 per cent of patients, the researcher said. The researchers identified multiple compounds that protected cochlear cells from cisplatin, several of which are already approved to treat other conditions. Three of the ten most effective compounds were inhibitors of an enzyme called CDK2.

One of these CDK2 inhibitors, kenpaullone, was more effective than four other compounds that are currently in clinical trials for treating hearing loss, the researcher said. Injecting kenpaullone into the middle ear protected both mice and rats from cisplatin-induced hearing loss, they added. Moreover, kenpaullone also protected the hearing of mice to noise as loud as 100 dB.

"Given that 100-dB noise is in the range of noise insults commonly experienced by people in our society, kenpaullone could have significant clinical application in treating noise-induced hearing loss," said the lead author, Jian Zuo from the St. Jude Children's Research Hospital. In the case of cisplatin-induced hearing loss, kenpaullone appears to protect hair cells by preventing CDK2 from stimulating the production of toxic reactive oxygen species from the cells' mitochondria, the researcher said.

"The robust protection conferred by one-time local delivery of kenpaullone suggests that CDK2 inhibitors may transform the clinical prevention and treatment of cisplatin - and noise-induced hearing loss in patients," Zuo said in a paper published in the Journal of Experimental Medicine.