PDCD1 and neoplasm: Subsequently in 2016, the FDA approved monotherapy with the PD-1 inhibitor pembrolizumab in the first-line setting for patients with metastatic NSCLC with programmed cell death 1 ligand 1 (PD-L1) Tumor Proportion Score (TPS) ≥ 50% and expanded the indication in April 2019 based on the results of the KEYNOTE-042 trial for the first-line treatment of patients with stage III patients who are not candidates for surgical resection or definitive CRT or metastatic NSCLC with TPS ≥ 1% determined by an FDA-approved test.