Blocking the PD-1/PD-L1 interaction with anti-PD-1 or PD-L1 antibodies could reverse the dysfunctional status of PD-1+NK cells, which manifests as significantly augmented production of cytokines, NK cell cytotoxicity, and marked suppression of tumor growth in vivo (67, 69–71). Here, PDCD1 is linked to neoplasm.