A Study of the Safety and Efficacy of Various Combinations of Avelumab as Therapy in Locally Advanced or Metastatic Urothelial Carcinoma (JAVELIN Bladder Medley)

Inclusion Criteria: * Participants with histologically confirmed, unresectable locally advanced or metastatic urothelial carcinoma. Both transitional cell and mixed transitional/non- transitional cell histologies are allowed, but transitional cell carcinoma must be the predominant histology * Participants has documented Stage IIIA/IIIB with N1-N3, or Stage IV disease (per American Joint Committee on Cancer/International Union for Cancer Control Tumor Node Metastasis system, 8th edition) at the start of first line chemotherapy. * The last dose of first line chemotherapy must have been received no less than 4 weeks, and no more than 10 weeks, prior to randomization in the present study * Estimated life expectancy of at least 3 months * Participants without progressive disease as per RECIST v1.1 guidelines following completion of 4 to 6 cycles of 1L chemotherapy. Eligibility based on this criterion will be determined by Investigator review of pre chemotherapy and post chemotherapy radiological assessments (CT/MRI scans). * Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0 or 1 * Adequate hematological, hepatic, and renal function as defined in the protocol * Other protocol defined inclusion criteria could apply Exclusion Criteria: * Participants with prior immunotherapy with Interleukin-2 (IL-2), IL-15, interferon alfa (IFN-α), or an anti programmed death receptor-1 (PD-1), anti programmed death-ligand 1 (PD-L1), anti PD-L2, anti CD137, or cytotoxic T cell l…