LAG-3

Class

Anti-LAG-3 monoclonal antibody

LAG-3 (lymphocyte-activation gene 3) is a receptor expressed on the surface of activated T cells and some other immune cells. It belongs to the family of inhibitory immune checkpoints, proteins that dampen T-cell activity once they engage their ligands, most notably molecules of the major histocompatibility complex class II found on antigen-presenting and tumor cells. Under normal circumstances, this restraint prevents excessive or prolonged immune responses that could damage healthy tissue. Cancers can co-opt this same mechanism, driving LAG-3 expression on tumor-infiltrating T cells to blunt the immune attack against malignant cells, a state often described as T-cell exhaustion. Monoclonal antibodies that bind LAG-3 block its inhibitory signaling, helping to restore the functional capacity of these exhausted T cells so they can again recognize and destroy tumor cells. Because LAG-3 acts through a pathway distinct from, though overlapping with, other checkpoints such as PD-1, blocking it is frequently explored alongside PD-1 pathway blockade to achieve a broader lifting of immune restraint than either approach alone. This general strategy of checkpoint blockade underlies much of modern immuno-oncology and is being investigated across a range of solid and hematologic malignancies where T-cell exhaustion contributes to tumor immune evasion.