Consolidation Pembrolizumab Following Chemoradiation in Patients With Inoperable/Unresectable Stage III NSCLC

OUTLINE: This is a multi-center study. Eligible patients must have completed concurrent chemoradiation with a standard chemotherapy regimen (either cisplatin/etoposide or carboplatin/paclitaxel) and a dose of radiation ranging from 59.4-66.6Gy, with restaging completed 28 days to 56 days post-chemoradiation. Patients with progressive disease will not be eligible for investigational treatment. Patients with stable disease/response will be eligible to register for investigational treatment of consolidation therapy to begin a minimum of 28 days and a maximum of 56 days from completion of chemoradiotherapy. INVESTIGATIONAL TREATMENT: Pembrolizumab, 200 mg IV every 3 weeks (until progressive disease (PD), unacceptable toxicity, or after 12 months (52 weeks) of therapy with pembrolizumab. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. Hematopoietic: * Absolute neutrophil count (ANC) ≥1,500/mcL * Platelets ≥100,000/mcL * Hemoglobin ≥9 g/dL or ≥5.6 mmol/L Renal: * Serum creatinine OR measured or calculated creatinine clearance ≤1.5 X institutional upper limit of normal (ULN) OR ≥60 mL/min for subject with creatinine levels \> 1.5 X institutional ULN (glomerular filtration rate (GFR) can also be used in place of creatinine or CrCl) Hepatic: * Serum total bilirubin ≤ 1.5 X institutional ULN OR direct bilirubin ≤ ULN for subjects with total bilirubin levels \> 1.5 institutional ULN * Aspartate transaminase (AST), serum glutamic oxaloacetic transaminase (SGOT), alanine transaminase (ALT), serum glutamic pyruvic transaminase (SGPT) ≤ 2.5 X institutional ULN Coagulation: * International Normalized Ratio (INR) or Prothrombin Time (PT) ≤1.5 X institutional ULN unless subject is receiving anticoagulant therapy as long as PT/INR/PTT is within therapeutic range of intended use of anticoagulants.