A Clinical Study of MK-3120 in People With Bladder Cancer (MK-3120-003)

Inclusion Criteria: * Has histologically confirmed carcinoma in situ (CIS) +/- papillary high-risk non-muscle invasive bladder cancer (NMIBC), confirmed locally. * Is an individual whose most recent transurethral resection of bladder tumor (TURBT) was performed within 12 weeks before allocation and showed high-risk NMIBC histology. For individuals with papillary tumors (Ta and T1), a complete TURBT must have been performed, as characterized by attainment of a visually complete resection of all papillary tumors (Ta and T1). * Is either: a) Bacillus Calmette-Guérin (BCG)-naïve, defined as either having never received BCG or having received BCG more than 2 years before CIS +/- papillary high-risk NMIBC recurrence. Recurrence must be at least 24 months from the last exposure to BCG with evidence of complete response during the 2-year period post-BCG OR; b) BCG-exposed and received adequate BCG therapy and had recurrence of CIS +/- papillary high-risk NMIBC \>12 months but ≤24 months after the last BCG dose. * Human immunodeficiency virus (HIV)-infected participants must have well-controlled HIV on antiretroviral therapy. * Participants who are hepatitis B surface antigen positive are eligible if they have received hepatitis B virus (HBV) antiviral therapy for at least 4 weeks, and have undetectable HBV viral load prior to allocation. * Participants with history of hepatitis C virus (HCV) infection are eligible if HCV viral load is undetectable at screening. Exclusion Criteria: …