T-cell immune checkpoint (ICP)

T-cell immune checkpoints are a diverse group of cell-surface receptors and ligands that function as critical regulators of the immune system's intensity and self-tolerance. These molecules can be broadly categorized into co-inhibitory signals, such as Programmed Cell Death Protein 1 (PD-1) and Cytotoxic T-Lymphocyte Associated Protein 4 (CTLA-4), which dampen immune responses, and co-stimulatory signals, such as CD28 or OX40, which amplify them (Pardoll, 2012, Nature Reviews Cancer). In many cancers, tumors exploit inhibitory checkpoint pathways to evade detection and destruction by the immune system. Therapeutic intervention typically involves the use of monoclonal antibodies, known as checkpoint inhibitors, which block these inhibitory interactions to restore and enhance the anti-tumor activity of T-cells (NCI Dictionary of Cancer Terms). While highly effective in treating various malignancies, these therapies can also lead to immune-related adverse events (irAEs) due to the loss of peripheral tolerance, resulting in inflammation of healthy tissues (PubMed, 2017, PMID: 28303822). The clinical success of targeting these molecules has revolutionized oncology, leading to the approval of numerous drugs across multiple cancer types. Ongoing research focuses on identifying new checkpoint targets, such as LAG-3 and TIM-3, and developing combination therapies to overcome resistance.

Other names

Immune checkpointCo-inhibitory receptorCo-stimulatory receptorT-cell regulatorCheckpoint protein

Blockade of inhibitory signaling pathways (e.g., PD-1/PD-L1 or CTLA-4) to restore T-cell mediated anti-tumor immunity or agonism of stimulatory pathways to treat autoimmunity.