PDCD1 and non-small cell lung carcinoma: The anti-programmed cell death protein 1 (PD-1) monoclonal antibody pembrolizumab has been shown to improve survival as monotherapy in the first-line setting of patients with advanced NSCLC and expression of programmed death-ligand 1 (PD-L1) in >50% of cancer cells2 and in combination with platinum-based chemotherapy in all patients with advanced disease irrespective of PD-L1 immunohistochemical expression.3