KEYNOTE-676: This study is assessing whether a combination of immunotherapies (pembrolizumab and Bacillus Calmette-Guerin) is more effective than Bacillus Calmette-Guerin alone in the treatment of high-risk non-muscle invasive breast cancerA Phase 3, Randomized, Comparator-controlled Clinical Trial to Study the Efficacy and Safety of Pembrolizumab (MK-3475) in Combination With Bacillus Calmette-Guerin (BCG) in Participants With High-risk Non-muscle Invasive Bladder Cancer (HR NMIBC) That is Either Persistent or Recurrent Following BCG Induction or That is Naïve to BCG Treatment

Exclusion

• Has a history of or concurrent locally advanced (i.e., T2, T3, T4) or metastatic UC
• Has concurrent extra-vesical (i.e, urethra, ureter, renal pelvis) non-muscle invasive urothelial carcinoma or a history of extra-vesical non-muscle invasive UC
• Has received prior therapy with anti-PD-1, anti-PD-L1, or anti-PD-L2 agent or with an agent directed to another stimulatory or co-inhibitory T-cell receptor
• Has received prior systemic anti-cancer therapy including investigational agents within 4 weeks of start of study treatment
• Is currently participating in or has participated in a study of an investigational agent or has used an investigational device within 4 weeks of start of study treatment
• Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy or any other form of immunosuppressive therapy within 7 days of start of study treatment
• Has a known additional malignancy that is progressing or requires active treatment within the past 3 years
• Has an active autoimmune disease that has required systemic treatment in past 2 years
• Has a history of (non-infectious) pneumonitis/interstitial lung disease that required steroids or has current pneumonitis/interstitial lung disease
• Has one or more of the following contraindications to BCG: prior BCG sepsis or systemic infection, total bladder incontinence, or an adverse experience to a previous BCG instillation that resulted in treatment discontinuation and precludes retreating with BCG
• Has an active infection or diagnosis requiring systemic antimicrobial therapy
• Has a known history of human immunodeficiency virus (HIV) infection
• Has a known history of Hepatitis B or known active Hepatitis C virus infection
• Has current active tuberculosis
• Has had an allogenic-tissue/solid organ transplant
• Has any contraindication(s) to IV contrast or is otherwise unable to have screening imaging with IV contrast performed

BCG Post-induction Cohort (Cohort A) Only - Has persistent T1 disease following an induction course of BCG

BCG Naïve Cohort (Cohort B) Only

- Has received any prior treatment with BCG for their NMIBC within the past 2 years prior to study entry