PDCD1 and neoplasm: Besides, higher levels of GZMA and XCL1 were observed in the NK cells from the PD-1+SMI group compared with those in the remaining groups, suggesting that the PD-1 inhibitor combined with SMI induced cytotoxic NK cells to infiltrate the NSCLC tumor and may recruit DCs into the tumor via NK cells, thus improving the antitumor efficacy.