Hsu et al. demonstrated that NK cells were essential for the therapeutic efficacy of PD-1/PD-L1 pathway blockade against RMA-S or CT26 mouse tumors engineered to express PD-L1 [79]; and Huang et al. used a mouse glioma model to illustrate the ability of anti-PD-1 mAbs to improve the efficacy of adoptive NK cell transfer therapy [95]. The gene discussed is PDCD1; the disease is central nervous system cancer.