Fig. 3. Cancer immunity cycle (Reprinted from Immunity, Vol. 39 Issue 1, Daniel S. Chen, Ira Mellman, Oncology meets immunology: the cancer-immunity cycle, page 10, Copyright (2013)32, with permission from Elsevier (Supplementary Material)).
The cycle consists of step-wise events characterising the immune response against cancer cells. Various stimulatory and inhibitory immune factors play a role in each event by activating or suppressing the anti-cancer immune response. Immune checkpoints such as CTLA-4, PD-1, PD-L1 and LAG-3 act as inhibitory factors to suppress T cell activation and prevent the killing of cancer cells.