Study of Tislelizumab in Combination With Chemotherapy Compared to Chemotherapy Alone for Participants With Urothelial Carcinoma

Key Inclusion Criteria:

• Male or female aged 18 to 75 years on the day of signing the Informed Consent Form (ICF)
• Histologically confirmed, inoperable, locally advanced, or metastatic urothelial cancer (UC)
• Must be eligible to receive cisplatin or carboplatin in the investigator's judgment
• Have had no prior systemic chemotherapy for locally advanced or metastatic UC
• Must be able to provide fresh or archival tumor tissues with an associated pathological report.
• Must have evaluable disease (either measurable or non-measurable) as defined per RECIST v1.1.
• Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1.
• Adequate organ function before randomization:

Key Exclusion Criteria:

• Received prior therapies targeting PD-1, PD-L1, PD-L2, CTLA4, or any other antibody or drug specifically targeting T-cell co-stimulation or checkpoint pathways.
• Any approved anticancer therapy within 28 days before randomization.
• Active leptomeningeal disease or uncontrolled, untreated brain metastasis
• Participants with uncontrolled hypercalcemia
• Participants with active autoimmune diseases or history of autoimmune diseases that may relapse
• History of interstitial lung disease, noninfectious pneumonitis, or uncontrolled diseases
• A known history of HIV infection.
• Prior allogeneic stem cell transplantation or organ transplantation.
• History of severe hypersensitivity reactions to other monoclonal antibodies. 10．History of allergic reactions to cisplatin, carboplatin, or other platinum-containing compounds.

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