Alterations in DNA Damage Repair Genes Before and After Neoadjuvant Cisplatin-based Chemotherapy in Muscle-invasive Bladder Cancer

BACKGROUND AND OBJECTIVE: The role of genetic variants in response to systemic therapy in muscle-invasive bladder cancer (MIBC) is still elusive. We assessed variations in genes involved in DNA damage repair (DDR) before and after cisplatin-based neoadjuvant chemotherapy (NAC) and correlation of alteration patterns with DNA damage and response to therapy. METHODS: Matched tissue from 46 patients with MIBC was investigated via Ion Torrent–based next-generation sequencing using a self-designed panel of 30 DDR genes. Phosphorylation of γ-histone 2A.X (H2AX) was analyzed via immunohistochemistry to evaluate DNA damage. Genetic variants were analyzed along with clinical data and quantitative phospho-H2AX data using the Kaplan-Meier method, Cox regression analysis, and factor analysis of mixed data. KEY FINDINGS AND LIMITATIONS: Twenty-five patients (54%) had a response (