Study of Pembrolizumab (MK-3475) Versus Placebo in Participants With Esophageal Carcinoma Who Are Receiving Chemotherapy and Radiation Therapy (MK-3475-975/KEYNOTE-975)

Has direct invasion of tumor into adjacent organs such as the aorta or trachea or has radiographic evidence of \>90 degree encasement or invasion of a major blood vessel, or of intratumoral cavitation

Has had major surgery other than for insertion of a feeding tube, open biopsy, or significant traumatic injury within 28 days prior to randomization, or anticipates the need for major surgery during study treatment; participants with gastric or esophageal fistulae are excluded

Has had weight loss of \>20% in the previous 3 months

Has had prior chemotherapy or radiotherapy for esophageal cancer

Has had a myocardial infarction within the past 6 months

Has symptomatic congestive heart failure

Has received prior therapy with an anti-programmed cell death-1 (anti-PD-1), anti-programmed cell death-ligand 1 (anti-PD-L1), or anti-programmed cell death-ligand 2 (anti-PD-L2) agent or with an agent directed to another stimulatory or coinhibitory T-cell receptor (e.g. cytotoxic T-lymphocyte-associated protein 4 \[CTLA-4\], OX-40, CD137)

Has received a live or live-attenuated vaccine within 30 days prior to the first dose of study intervention; administration of killed vaccines is allowed

Has received any prior systemic anticancer therapy for esophageal cancer including investigational agents

Has not recovered from all adverse events (AEs) due to previous non-anticancer therapies to ≤Grade 1 or Baseline

Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior the first dose of study treatment

Has a known additional malignancy that is progressing or has required active treatment within the past 3 years. Note: Participants with basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or carcinoma in situ (e.g. breast carcinoma, cervical cancer in situ) that have undergone potentially curative therapy are not excluded from the study. Participants with localized prostate cancer that has undergone potentially curative treatment can be enrolled in the study.

Has severe hypersensitivity (≥Grade 3) to pembrolizumab, any of the study chemotherapy agents, or their excipients

Has an active autoimmune disease that has required systemic treatment in past 2 years

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)

Is pregnant or breastfeeding or expecting to conceive or father children within the projected duration of the study, starting with the screening visit through 120 days after the last dose of study treatment (180 days for participants receiving cisplatin who are breastfeeding)

Has had an allogeneic tissue/solid organ transplant

What this study is about