Immune Checkpoint Inhibitor

An immune checkpoint inhibitor is a major category of cancer immunotherapy drug that blocks inhibitory checkpoint receptors, proteins that normally slow the immune response and prevent the immune system from attacking the body's own cells. By binding to these proteins and preventing them from functioning normally, checkpoint inhibitors increase immune system activity against tumors, including through the PD-1 and PD-L1 pathway and the CTLA-4 pathway, both of which normally limit immune cell activity until blocked by these drugs.