Clinical and Genome-wide Analysis of Cisplatin-induced Tinnitus Implicates Novel Ototoxic Mechanisms.

Purpose: Cisplatin, a commonly used chemotherapeutic, results in tinnitus, the phantom perception of sound. Our purpose was to identify the clinical and genetic determinants of tinnitus among testicular cancer survivors (TCS) following cisplatin-based chemotherapy.
Experimental Design: TCS ( n = 762) were dichotomized to cases (moderate/severe tinnitus; n = 154) and controls (none; n = 608). Logistic regression was used to evaluate associations with comorbidities and SNP dosages in genome-wide association study (GWAS) following quality control and imputation (covariates: age, noise exposure, cisplatin dose, genetic principal components). Pathway over-representation tests and functional studies in mouse auditory cells were performed.
Results: Cisplatin-induced tinnitus (CisIT) significantly associated with age at diagnosis ( P = 0.007) and cumulative cisplatin dose ( P = 0.007). CisIT prevalence was not significantly greater in 400 mg/m ² -treated TCS compared with 300 ( P = 0.41), but doses >400 mg/m ² (median 580, range 402-828) increased risk by 2.61-fold ( P < 0.0001). CisIT cases had worse hearing at each frequency (0.25-12 kHz, P < 0.0001), and reported more vertigo (OR = 6.47; P < 0.0001) and problems hearing in a crowd (OR = 8.22; P < 0.0001) than controls. Cases reported poorer health ( P < 0.0001) and greater psychotropic medication use (OR = 2.4; P = 0.003). GWAS suggested a variant near OTOS (rs7606353, P = 2 × 10 ^-6 ) and OTOS eQTLs were significantly enriched independently of that SNP ( P = 0.018). OTOS overexpression in HEI-OC1, a mouse auditory cell line, resulted in resistance to cisplatin-induced cytotoxicity. Pathway analysis implicated potassium ion transport (q = 0.007).
Conclusions: CisIT associated with several neuro-otological symptoms, increased use of psychotropic medication, and poorer health. OTOS , expressed in the cochlear lateral wall, was implicated as protective. Future studies should investigate otoprotective targets in supporting cochlear cells.
(©2019 American Association for Cancer Research.)