Immune checkpoint

Immune checkpoints are regulators of the immune system. These pathways are crucial for self-tolerance, which prevents the immune system from attacking cells indiscriminately.

Inhibitory checkpoint molecules have been increasingly considered as new targets for cancer immunotherapy due to their potential for use in multiple types of cancers. Currently approved checkpoint inhibitors block CTLA4 and PD-1 and PD-L1.

Four stimulatory checkpoint molecules are members of the tumor necrosis factor (TNF) receptor superfamily - CD27, CD40, OX40, GITR and CD137. Another two stimulatory checkpoint molecules belongs to the B7-CD28 superfamily - CD28 itself and ICOS.

Drugs or drug candidates that inhibit/block the inhibitory checkpoint molecules are sometimes known as checkpoint inhibitors; this idea is often referred to as immune checkpoint blockade, or simply checkpoint blockade. Checkpoint inhibitor drugs have seen growth in pharmaceutical research in cancer by companies including Merck and AstraZeneca.

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