Figure 1.

Schematic symphony of peptides in cancer-immunity cycle (CIC). CIC can be divided into seven steps (numbered 1–7): 1) antigens release from dying tumor cells, 2) APCs uptake tumor antigens, 3) T-cell priming and activation in local lymph nodes, 4) trafficking of T cells to tumors via blood vessels, 5) infiltration of T cells into tumor tissues, 6) recognition of tumor cells by T cells, and 7) T-cell-mediated killing of tumor cells in the tumor microenvironment; then, dying tumor cells further contribute to a new round of CIC. Among them, peptides are mainly involved in four steps of the above cycle: (A) therapeutic vaccines, (B) improving APC activation, (C) enhancing T-cell response, and (D) strengthening T-cell recognition.