Abstract
The widely used chemotherapy cisplatin causes permanent hearing loss in 40-60% of cancer patients. One drug, sodium thiosulfate, is approved by the FDA for use in pediatric patients with localized solid tumors for preventing cisplatin-induced hearing loss, but more drugs are desperately needed. Here, we tested dabrafenib, an FDA-approved BRAF kinase inhibitor and anticancer drug, in a clinically relevant multi-dose cisplatin mouse model. The protective effects of dabrafenib, given orally twice daily with cisplatin, were determined by functional hearing tests and cochlear outer hair cells counts. Toxicity of the drugs co-treatment was evaluated, and levels of pERK were measured. Dabrafenib, in dose of 3 mg/kg/bw, twice daily, in mice, was determined to be the minimum effective dose and it is equivalent to one tenth of the daily FDA-approved dose for human cancer treatment. The levels of hearing protection acquired, 20-25 dB at the three frequencies tested, in both female and male mice, persisted for four months after completion of treatments. Moreover, dabrafenib exhibited a good in vivo therapeutic index (> 25), hearing protection in two different mouse strains, and diminished cisplatin-induced weight loss. Altogether, this study demonstrates that dabrafenib is a promising candidate drug for protection from cisplatin-induced hearing loss.