Study of Pembrolizumab (MK-3475) in Participants With Advanced Non-small Cell Lung Cancer (MK-3475-025/KEYNOTE-025)

Inclusion Criteria:

* Histologically or cytologically confirmed diagnosis of non-small cell lung cancer (NSCLC) that is PD-L1 positive per central laboratory review
* At least one measurable lesion
* Radiographic progression of NSCLC after treatment with a platinum-containing doublet for Stage IIIB/IV or recurrent disease
* Eastern Cooperative Oncology Group (ECOG) Performance Scale 0 or 1
* Adequate organ function

Exclusion Criteria:

* Systemic cytotoxic chemotherapy, biological therapy, or major surgery within 3 weeks of the first dose of trial treatment
* Systemic steroid therapy within 3 days prior to the first dose of trial treatment or any other form of immunosuppressive medication
* Expected to require any other form of systemic or localized antineoplastic therapy while on trial
* History of prior malignancy, with the exception of basal cell carcinoma of the skin, superficial bladder cancer, squamous cell carcinoma of the skin, or in situ cancer
* Active central nervous system (CNS) metastases and/or carcinomatous meningitis
* Active autoimmune disease or documented history of autoimmune disease or syndrome that requires systemic steroids or immunosuppressive agents
* Prior therapy with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) antibody
* Concurrent or past history of interstitial lung disease
* Pregnant or breast-feeding, or expecting to conceive or father children within the projected duration of the study, starting with screening visit through 120 days after the last dose of pembrolizumab