Efficacy and Safety of Pembrolizumab (MK-3475) in Combination With Chemoradiotherapy (CRT) Versus CRT Alone in Muscle-invasive Bladder Cancer (MIBC) (MK-3475-992/KEYNOTE-992)

Inclusion Criteria:

Has a histologically confirmed initial diagnosis of muscle-invasive bladder cancer (MIBC) with predominant urothelial histology
Has clinically nonmetastatic bladder cancer (N0M0)
Has planned and is eligible to receive chemoradiotherapy (CRT) and one of the protocol-specified radiosensitizing chemotherapy regimens
Has Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2
Demonstrates adequate organ function

Male participants are eligible to participate if they agree to the following during the intervention period and for at least 90 days after the last dose of CRT treatment:

Refrain from donating sperm
Be abstinent from heterosexual intercourse as their preferred and usual lifestyle (abstinent on a long term and persistent basis) and agree to remain abstinent; or must agree to use contraception unless confirmed to be azoospermic

A female participant is eligible to participate if she is not pregnant or breastfeeding, and at least one of the following conditions applies:

Is not a woman of childbearing potential (WOCBP)
Is a WOCBP and using a contraceptive method that is highly effective (with a failure rate of <1% per year), with low user dependency or be abstinent from heterosexual intercourse as their preferred and usual lifestyle (abstinent on a long term and persistent basis), during the intervention period and for at least 180 days the time needed to eliminate each study intervention after the last dose of study intervention; and agrees not to donate eggs (ova, oocytes) to others or freeze/store for her own use for the purpose of reproduction during this period. The length of time required to continue contraception for each study intervention is as follows: MK-3475 - 120 days and CRT - 180 days

Exclusion Criteria:

Has the presence of diffuse carcinoma in situ (CIS) (multiple foci of CIS) throughout the bladder
Has the presence of urothelial carcinoma (UC) at any site outside of the urinary bladder in the previous 2 years except for Ta stage/T1 stage/CIS of the upper tract if the participant has undergone a complete nephroureterectomy
Has a known additional malignancy that is progressing or has required active therapy within the past 3 years, except basal cell carcinoma of the skin, squamous cell carcinoma of the skin, superficial bladder cancer or other carcinoma in situ that has undergone potentially curative therapy
Has the presence of bilateral hydronephrosis
Has limited bladder function with frequency of small amounts of urine (< 30 mL), urinary incontinence, or requires self-catheterization or a permanent indwelling catheter
Has received prior pelvic/local radiation therapy or any antineoplastic treatment for muscle-invasive bladder cancer (MIBC). Treatment for non-muscle invasive bladder cancer (NMIBC) with intravesical instillation therapy that was completed ≥28 days prior to randomization is allowed. Prior systemic treatment of NMIBC is not permitted.
Received prior therapy with an anti-PD-1 (programmed cell death protein 1), anti-PD-L1 (programmed death-ligand 1), or anti-PD-L2 (programmed cell death 1 ligand 2), or with an agent directed to another stimulatory or coinhibitory T-cell receptor (e.g., CTLA-4 [cytotoxic T-lymphocyte-associated protein 4], OX 40, or CD137 [cluster of differentiation 137])
Has received a live vaccine within 30 days before the first dose of study medication
Is currently participating in or has participated in a study of an investigational agent or has used an investigational device within 4 weeks before the first dose of study medication
Has known severe hypersensitivity (≥Grade 3) to the selected chemotherapy regimen, and/or any of their excipients and excipients of pembrolizumab
Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form of immunosuppressive therapy within 7 days before the first dose of study medication
Has an active autoimmune disease that has required systemic treatment in the past 2 years (ie, with use of disease modifying agents, corticosteroids or immunosuppressive drugs). Replacement therapy (eg, thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency) is not considered a form of systemic treatment and is allowed
Has a history of non-infectious pneumonitis that required steroids or has current pneumonitis
Has an active infection requiring systemic 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 a known history of active tuberculosis (TB; Bacillus tuberculosis)
Has a known psychiatric or substance abuse disorder that would interfere with the participant's ability to cooperate with the requirements of the study
Has had an allogenic tissue/solid organ transplant