In healthy cells, checkpoints regulate immune responses to prevent overactivity, which could damage normal tissues. However, cancer cells exploit these checkpoints to protect themselves from immune attacks. Checkpoint inhibitors block these proteins, such as PD-1 (Programmed Death-1), PD-L1 (Programmed Death-Ligand 1), and CTLA-4 (Cytotoxic T-Lymphocyte-Associated Protein 4), thereby enabling T-cells to recognize and kill cancer cells.
