More recently, programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) immune checkpoint inhibitors (ICIs) showed potent activity against metastatic NSCLC in subsets of clinical trials (Borghaei et al. 2015; Brahmer et al. 2015; Herbst et al. 2016). The gene discussed is PDCD1; the disease is non-small cell lung carcinoma.