PDCD1 and neoplasm: Anti–PD-1/PD-L1 therapy (immunotherapy) works by disrupting the PD-1 and PD-L1 interactions in the tumor microenvironment, as well as in nontumor tissues (Li et al., 2017; Medina & Adams, 2016; Nishino et al., 2016a; Tada et al., 2017).