4543Background: CIPN is a potentially permanent side effect of cisplatin chemotherapy. CIPN remains a major clinical challenge due to lack of effective treatment, impact on quality of life and unexplained inter-individual variability. Methods: Testicular cancer patients (n = 847) given cisplatin-based therapy (median dose: 400 mg/m2) were assessed for responses to the validated EORTC QLQ-CIPN20 questionnaire. Associations were evaluated between frequency of sensory neuropathy and cumulative cisplatin dose, smoking history and age. Using the Illumina HumanOmniExpressExome chip and with imputation, 5.1 million SNPs passed quality control (QC) for GWAS inclusion. A gene-based method, PrediXcan, was used to consider associations between the genetically determined component of gene expression and CIPN. Results: Sensory neuropathy was common (57% having any symptom). CIPN sensory items (n = 8) indicated excellent internal consistency (alpha coefficient = 0.88). Using each patient’s mean sensory neuropathy score...