PDCD1 and non-small cell lung carcinoma: However, only ∼20% of unselected non-small cell lung cancer patients respond to monotherapy targeting the Programmed Cell Death Protein 1 (PD-1)/Programmed Death Ligand 1 (PD-L1) axis (Borghaei et al, 2015; Brahmer et al, 2015; Garon et al, 2015).