Inclusion criteria

          1. Have full knowledge on this study and are willing to sign informed consent form (ICF);

          2. Age 18-75 years at time of signing ICF, male or female;

          3. The investigator judged that the subject is eligible for platinum-based chemotherapy;

          4. Presence of histopathologically confirmed unresectable locally advanced (T4, any N; or
             any T, N2-3) or metastatic urothelial carcinoma;

          5. No prior systemic anti-tumor therapy;

          6. Subjects who are able to provide tumor tissue slides (≥ 5 slides) for PD-L1 test and
             the corresponding pathology report and whose PD-L1 test must be positive before
             randomization;

          7. With at least one measurable lesion as per RECIST 1.1 criteria;

          8. ECOG performance status score of 0-1;

          9. Adequate function of vital organs.

        Exclusion criteria

          1. Have received anti-tumor treatments, including chemotherapy, radiotherapy or
             investigational product within 28 days before randomization;

          2. Have received traditional Chinese medicines with anti-tumor activity or
             immunomodulators (eg. Interferon and Interleukin) within 14 days before randomization;

          3. Previous use of anti-PD-1/PD-L1 agent or a drug acting on another co-inhibitory T cell
             receptor;

          4. Subjects who are currently participating in or have participated in a study with
             investigational product within 4 weeks before administration;

          5. Having received systemic corticosteroid therapy (dose equivalent to prednisone > 10
             mg/day) within 14 days before randomization;

          6. Subjects with active central nervous system (CNS) metastasis;

          7. Grade 2 or higher peripheral neuropathy or hearing loss.