This is a Phase 2, single arm study of a tailored immunotherapy approach with nivolumab in adult (≥ 18 years) subjects with previously untreated (1st line) or pretreated (2nd and 3rd line), surgically unresectable or metastatic TCC (further designated "advanced TCC"). The study targets to recruit 130 untreated (1st line) and 120 pretreated (2nd / 3rd line) patients, respectively. Tumor tissue obtained at least 2 years prior to screening must be available for a central pathology assessment. Subjects must have advanced (not amenable to curative surgery or radiation) or metastatic TCC, and must not have received more than two prior platinum-based chemotherapies for the treatment of advanced TCC.