Key Inclusion Criteria:

          -  Provide written, informed consent to participate in the study and follow the study
             procedures

          -  Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 2

          -  Measurable disease per RECIST 1.1 criteria

          -  Histologically or cytologically documented inoperable, locally advanced or metastatic
             urothelial cell carcinoma (also termed TCC)

          -  Fresh biopsy or archival tissue

          -  No prior systemic chemotherapy or investigational agent for inoperable locally
             advanced or mUC

          -  Ineligible for cisplatin

        Key Exclusion Criteria:

          -  Patients who have an active, known or suspected autoimmune disease

          -  Patients must not have received prior IL-2 therapy

          -  Prior treatment with an anti PD-1, anti PD-L1, or anti cytotoxic T lymphocyte
             associated protein 4 (anti CTLA-4) antibody, agents that target IL-2 pathway, or any
             other antibody or drug specifically targeting T-cell co-stimulation or immune
             checkpoint pathways

          -  Patients with hypertension must be on a stable antihypertensive regimen for the 14
             days prior to Cycle 1 Day 1

        Additional protocol-defined inclusion/exclusion criteria will apply