• Objective Response Rate (ORR) [ Time Frame: Up to 3 Years, approximately ]
  Defined as the proportion of participants who had confirmed complete response (CR) or partial response (PR) assessed by Independent Review Committee (IRC) using RECIST version 1.1
• Duration of Response (DOR) [ Time Frame: Up to 3 Years, approximately ]
  Defined as the time from the first determination of a confirmed objective response by IRC according to RECIST version 1.1 until the first documentation of progression or death, whichever comes first
• Progression-Free Survival (PFS) [ Time Frame: Up to 3 Years, approximately ]
  Defined as the time from the date of first dose of study drug to the date of first documentation of disease progression assessed by IRC using RECIST version 1.1 or death, whichever occurs first
• Disease Control Rate (DCR) [ Time Frame: Up to 3 Years, approximately ]
  Defined as the proportion of participants who achieve CR, PR and stable disease (SD) assessed by IRC using RECIST version 1.1
• Overall Survival (OS) [ Time Frame: Up to 3 Years, approximately ]
  Defined as the time from the date of first dose of study drug until the date of death from any cause

• Objective Response Rate (ORR) [ Time Frame: Up to 3 Years, approximately ]
  Defined as the proportion of subjects who had confirmed complete response (CR) or partial response (PR) assessed by IRC using RECIST version 1.1
• Duration of Response (DOR) [ Time Frame: Up to 3 Years, approximately ]
  Defined as the time from the first determination of a confirmed objective response by IRC according to RECIST version 1.1 until the first documentation of progression or death, whichever comes first
• Progression-Free Survival (PFS) [ Time Frame: Up to 3 Years, approximately ]
  Defined as the time from the date of first dose of study drug to the date of first documentation of disease progression assessed by IRC using RECIST version 1.1 or death, whichever occurs first
• Disease Control Rate (DCR) [ Time Frame: Up to 3 Years, approximately ]
  Defined as the proportion of subjects who achieve CR, PR and stable disease (SD) assessed by IRC using RECIST version 1.1
• Overall Survival (OS) [ Time Frame: Up to 3 Years, approximately ]
  Defined as the time from the date of first dose of study drug until the date of death from any cause

Key Inclusion Criteria:

1. Participants with histologically or cytologically documented locally advanced or metastatic transitional cell carcinoma (TCC) of the urothelium
2. Disease progression during or following treatment with at least one platinum-containing regimen for inoperable locally advanced or metastatic urothelial carcinoma or disease recurrence
3. Participants must submit archival tumor tissue for determination of program death ligand-1 (PD-L1) expression and other biomarker analyses. PD-L1 expression will be assessed centrally, and participants who are tested as PD-L1 high are eligible.
4. Participants must have at least one measurable lesion as defined per RECIST version 1.1 assessed by the investigator
5. Male or female, aged ≥18 years on day of signing informed consent
6. Participants have voluntarily agreed to participate by giving written informed consent
7. Eastern Cooperative Oncology Group (ECOG) performance status of ≤1
8. Life expectancy ≥12 weeks

9. Participant must have adequate organ function as indicated by the following screening laboratory values obtained within 7 days prior to the first study treatment

   1. Absolute neutrophil count (ANC) ≥1.5×109/L
   2. Platelets ≥100×109/L
   3. Hemoglobin ≥9 g/dL or ≥5.6 mmol /L (Note: Criteria must be met without a transfusion within 14 days of obtaining the sample)
   4. Calculated creatinine clearance ≥ 30 milliliter (mL)/min (Cockcroft-Gault formula, see Appendix 5)
   5. Serum total bilirubin ≤ 1.5 X upper limit of normal (ULN) (total bilirubin must be <4 X ULN for participants with Gilbert's syndrome)
   6. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 X ULN OR ≤ 5 X ULN for participants with liver metastases

10. Female participants are eligible to enter and participate in the study if they are of:

    1. Non-childbearing potential (ie, physiologically incapable of becoming pregnant), including any female who i) Has had a hysterectomy ii) Has had a bilateral oophorectomy (ovariectomy) iii) Has had a bilateral tubal ligation iv) Is post menopausal (total cessation of menses for ≥1 year)
    2. Childbearing potential, has a negative serum pregnancy test at screening (within 7 days before the first investigational product administration), not be breast feeding, and agree to remain abstinent (refrain from heterosexual intercourse) or uses adequate contraceptive methods that result in a failure rate of <1% per year before study entry and throughout the study until 120 days after the last investigational product administration
11. Male participants are eligible to participate in the study if they are vasectomized or agree to use contraception during the study treatment period and for at least 120 days after the last dose of study drug

Key Exclusion Criteria:

1. History of severe hypersensitivity reactions to other humanized monoclonal antibodies
2. Prior active malignancy within 2 years prior to Cycle 1 Day 1.
3. Prior therapies targeting PD-1 or PD-L1.
4. Active brain or leptomeningeal metastases as determined by computed tomography (CT) or magnetic resonance imaging (MRI) evaluation during screening and prior radiographic assessments.
5. Participants with active autoimmune diseases or history of autoimmune diseases that may relapse should be excluded.
6. Participants should be excluded if they have conditions requiring systemic treatment with either corticosteroids (>10 mg daily prednisone equivalents) or other immunosuppressive medications within 14 days of study drug administration.
7. Has history of interstitial lung disease or non-infectious pneumonitis except for those induced by radiation therapies
8. With severe chronic or active infections (including tuberculosis infection, etc) requiring systemic antibacterial, antifungal or antiviral therapy within 14 days prior to first dose of study drug.
9. With uncontrollable pleural effusion, pericardial effusion or ascites requiring pleurocentesis or abdominal tapping less than 4 weeks
10. Significant cardiovascular disease, such as New York Heart Association (NYHA) cardiac disease (Class II or greater), myocardial infarction within the previous 3 months, unstable arrhythmias, or unstable angina
11. Known history of Human Immunodeficiency Virus (HIV)
12. Participants with untreated chronic hepatitis B or chronic hepatitis B virus (HBV) carrier with HBV deoxyribonucleic acid (DNA) ≥500 IU/mL (or 2.5 × 103 cps/mL), or active hepatitis C should be excluded. Participant with inactive hepatitis B surface antigen (HBsAg) carrier, active HBV infection with sustained anti-HBV suppression (HBV DNA <500 IU/mL or 2.5 × 103 cps/mL) and participants whose hepatitis C has been cured (hepatitis C virus [HCV] ribonucleic acid [RNA] is lower than detection limit) can be enrolled
13. Underlying medical conditions that, in the investigator's opinion, will make the administration of study drug hazardous or obscure the interpretation of toxicity determination or adverse events (AEs)
14. Prior chemotherapy, radiotherapy, immunotherapy or any investigational therapies (including Chinese herbal medicine and Chinese patent medicines) used to control cancer within 2 weeks of Cycle 1 Day 1. AEs associated with these therapies must be Grade 0-1, baseline or stabilized (except for alopecia)
15. Prior allogeneic stem cell or solid organ transplant
16. Administration of a live or attenuated vaccine within 4 weeks prior to study drug administration
17. Major surgical procedure other than for diagnosis within 28 days prior to study drug administration

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.