Immune checkpoint inhibitor

The term "checkpoint inhibitor" does not refer to a specific molecular target, but rather to a class of therapeutic agents—primarily monoclonal antibodies—that block immune checkpoint proteins on immune cells such as T lymphocytes or, less commonly, on tumor cells. The most widely targeted immune checkpoints in cancer therapy are PD-1, PD-L1, and CTLA-4. Checkpoint inhibitors prevent these proteins from inhibiting T cell activity, thereby boosting the immune system's ability to detect and destroy cancer cells. Drugs in this class have transformed the treatment landscape for multiple cancer types by providing durable responses for some patients, though their use is limited by serious immune-related side effects. Accurate description of a "checkpoint inhibitor" requires reference to its specific molecular target, such as "Programmed cell death protein 1 (PD-1)" or "Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4)"[5][6][4][1][2][3]. Note: "Checkpoint inhibitor" is a class/therapeutic approach, not a single molecule or receptor—thus, marking as is_incorrect=true for a molecular target index. Specific molecular targets within this class include PD-1, PD-L1, CTLA-4, LAG-3, etc.

Other names

Checkpoint inhibitorImmune checkpoint blockadeICI

Blockade of immune checkpoint receptors or ligands (e.g., PD-1, PD-L1, CTLA-4) on T cells and/or tumor cells, thereby preventing negative regulation of the immune response and enabling enhanced T cell activation against cancer cells[5][6].