•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 PD-L2 agent or with an agent directed to another stimulatory or co-inhibitory T-cell receptor (e.g. cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4], tumor necrosis factor receptor superfamily member 4 [OX-40], tumor necrosis factor receptor superfamily member 9 [CD137])
•Has received prior radiotherapy to the thorax, including radiotherapy to the esophagus, mediastinum, or breast
•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 the first dose of study treatment. Note: Participants who have entered the follow-up phase of an investigational study may participate as long as it has been 4 weeks after the last dose of the previous investigational agent
•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 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.
•Has a known hypersensitivity (≥Grade 3) to pembrolizumab and/or any of its excipients
•Has a history of (non-infectious) pneumonitis that required steroids or has current pneumonitis
•Has a known history of Hepatitis B or known active Hepatitis C virus infection
•Has an active autoimmune disease that has required systemic treatment in past 2 years (i.e., with use of disease modifying agents, corticosteroids or immunosuppressive drugs). However, replacement therapy (e.g. thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency), while systemic, will be permitted for study eligibility.
•Has an active infection requiring systemic therapy
•Has a known history of human immunodeficiency virus (HIV) 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
•Has had an allogenic tissue/solid organ transplant
