• Participants must have the capacity to participate/enroll in the study and to provide informed consent

• Histologically confirmed muscle-invasive UC (also termed TCC) of the bladder or upper urinary tract

• TNM classification (UICC/AJCC 7th edition) at pathological examination of surgical resection specimen of (y)pT3-4 or (y)pN+ and M0

• Surgical resection of MIUC of the bladder or upper tract

• Participants who have not received prior neoadjuvant cisplatin chemotherapy (NAC) must be ineligible to receive adjuvant cisplatin therapy due to participant refusal, cisplatin ineligibility or investigator decision

• Tumor tissue must be provided for biomarker analysis

• Absence of residual disease and absence of metastasis, as confirmed by a negative baseline Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) scan of the pelvis, abdomen, and chest no more than 28 days prior to randomization.

• Full recovery from cystectomy or nephroureterectomy within 120 days following surgery

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

• Negative HIV test at screening

• Negative hepatitis B surface antigen (HbsAg) test at screening

• Positive hepatitis B surface antibody (HBsAb), or a negative HBsAb at screening accompanied by either of the following: negative total hepatitis B core antibody (HBcAb) or positive total HBcAb test followed by quantitative hepatitis B virus (HBV) DNA \< 500 international units/milliliter (IU/mL)

• Negative hepatitis C virus (HCV) antibody test at screening, or a positive HCV antibody test followed by a negative HCV RNA test at screening