Safety and Efficacy of Pembrolizumab (MK-3475) Versus Placebo as Adjuvant Therapy in Participants With Hepatocellular Carcinoma (HCC) and Complete Radiological Response After Surgical Resection or Local Ablation (MK-3475-937 / KEYNOTE-937)

Exclusion Criteria

• •Has a known additional malignancy that is progressing or has required active antineoplastic treatment (including hormonal) or surgery within the past 3 years.
• •Has had esophageal or gastric variceal bleeding within the last 6 months.
• •Has clinically apparent ascites on physical examination.
• •Has had clinically diagnosed hepatic encephalopathy in the last 6 months.
• •Has received local therapy to liver ablation other than with radiofrequency or microwave ablation.
• •Has a history of (noninfectious) pneumonitis/interstitial lung disease that required steroids or has current pneumonitis/interstitial lung disease.
• •Has an active infection requiring systemic therapy.
• •Has dual active Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV) infection at study entry.
• •Has a known history of human immunodeficiency virus (HIV) infection.
• •Has known active tuberculosis (TB; Bacillus tuberculosis).
• •Has received prior therapy with an 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 (eg, CTLA-4, OX-40, CD137).
• •Has received prior systemic anti-cancer therapy for HCC including investigational agents.
• •Is receiving any of the following prohibited concomitant therapies:1) Antineoplastic systemic chemotherapy or biological therapy; 2) Immunotherapy not specified in this protocol; 3) Investigational agents other than pembrolizumab; 4) Radiation therapy; 5) Oncological surgical therapy; or systemic glucocorticoids for any purpose other than to modulate symptoms from an AE that is suspected to have an immunologic etiology.
• •Has received a live vaccine within 30 days prior to the first dose 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 prior to Cycle 1, Day 1.
• •Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to Cycle 1, Day 1.
• •Has severe hypersensitivity (≥Grade 3) to pembrolizumab and/or any of its excipients.
• •Has an active autoimmune disease that has required systemic treatment in past 2 years.
• •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.