Chimeric antigen receptor target antigen (CAR target)

A CAR-recognized cell-surface antigen is a generic term for any protein or molecule expressed on the exterior of a cell that is specifically targeted by a Chimeric Antigen Receptor (CAR). These antigens serve as the primary docking sites for engineered immune cells, such as CAR-T or CAR-NK cells, allowing them to identify and eliminate specific cell populations, most commonly malignant cells. The most well-validated examples include CD19, targeted in B-cell leukemias and lymphomas, and B-cell maturation antigen (BCMA), targeted in multiple myeloma. Unlike native T-cell receptors, CARs recognize these surface antigens in a major histocompatibility complex (MHC)-independent manner, which broadens the range of potential targets to include proteins, carbohydrates, and lipids. The selection of an appropriate antigen is the most critical factor in CAR therapy design, as the ideal target must be highly and uniformly expressed on tumor cells while being absent or minimally expressed on essential healthy tissues to avoid severe 'on-target, off-tumor' toxicities.

Other names

CAR-recognized cell-surface antigenCAR-recognized antigenCAR-T targetCAR ligandTumor-associated antigen (TAA)

Chimeric Antigen Receptor (CAR) immune cells (typically T cells or NK cells) express a synthetic receptor that binds specifically to a cell-surface antigen. This binding triggers intracellular signaling through the CAR's endodomain (often containing CD3-zeta and co-stimulatory domains like 4-1BB or CD28), leading to the activation, proliferation, and cytotoxic activity of the immune cell against the antigen-expressing target cell.