TLR4 downregulation protects against cisplatin-induced ototoxicity in adult and pediatric patients with cancer.

Cisplatin causes permanent hearing loss or cisplatin-induced ototoxicity in over 50% of treated patients with cancer, leading to significant social and functional limitations. Interindividual variability in developing hearing loss suggests the role of genetic predispositions to cisplatin-induced hearing loss. We investigated genetic associations between cisplatin-induced ototoxicity and toll-like receptor 4 (TLR4), an immune receptor known to mediate inflammatory responses to cisplatin. Using a case-control candidate gene approach, we identified 20 single nucleotide polymorphisms at the TLR4 locus with significant protection against ototoxicity in a cohort of 213 adult patients, followed by an independent pediatric patient cohort (n = 357). Combined cohort analysis demonstrated a significant association between cisplatin-induced ototoxicity protection and a single variant in the TLR4 promoter, rs10759932. We showed that rs10759932 downregulated TLR4 expression that is normally induced by cisplatin. This work provides pharmacogenetic and functional evidence to implicate TLR4 with cisplatin-induced hearing loss in patients. SIGNIFICANCE STATEMENT: Adult and pediatric patients carrying toll-like receptor 4 (TLR4) genetic variants were protected against developing cisplatin-induced hearing loss following cisplatin treatment. Important variants in the TLR4 promoter disrupted a drug-gene interaction between cisplatin and TLR4, mirroring the protective effect conferred by genetic inhibition of TLR4. These variants have the potential to improve the prediction of cisplatin toxicity, allowing for more precise chemotherapy treatment.