PDCD1 and lung cancer: In the last decade, immune checkpoint inhibitors (ICIs) targeting the programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) axis had produced remarkably durable responses in non-small cell lung cancer (NSCLC) which accounts for about 85% of all lung cancers, leading to prolonged survival in select patients [2,3].