The programmed cell death-1(PD-1)/programmed cell death-ligand 1(PD-L1)pathway is important in the negative regulation of cell-mediated immune responses.Immunotherapy targeting the PD-1/PD-L1 axis has great promise in treating many types of cancer and was a breakthrough in cancer treatment.The cover art shows that the intensity of PD-1 expression on CD8(+)T cells in primary tumors and in metastatic lymph nodes were stronger than that in tumor-free lymph nodes from the same patient.For more details,please read the article on pages 560-573 of this CJC issue.