Unidentified tumor-associated antigen on tumor cells (TAA)

Unidentified tumor-associated antigen on tumor cells is a placeholder designation used in clinical and pharmacological databases, such as the National Cancer Institute (NCI) Drug Dictionary, to describe the target of experimental therapies when the specific molecular identity of the antigen has not been publicly disclosed or fully characterized [1, 2, 20]. This terminology is typically applied to novel immunotherapies, including chimeric antigen receptor (CAR) T-cell therapies and antibody-based biologics, where the therapeutic agent is designed to bind a specific surface protein on cancer cells to induce immune-mediated destruction [1, 6]. For instance, the CAR-T therapy AMG 119 was initially described as targeting an unidentified tumor-associated antigen before its target was revealed to be Delta-like ligand 3 (DLL3) [7, 11]. Similarly, the biologic ABBV-461 is currently listed as targeting an unidentified antigen in its role as a switch for modular CAR-T systems like CLBR001 in breast cancer trials [6, 17]. Because the target is unidentified, its precise biological function and molecular family are unknown, though it is functionally defined by its selective expression on tumor tissue and its utility as a docking site for targeted anticancer agents [14, 16].

Other names

Tumor-associated antigenTAAUndisclosed tumor-associated antigenUnidentified TAAUndisclosed TAA

Binding of a therapeutic agent (such as a CAR-T cell or antibody fragment) to a surface antigen expressed on tumor cells to facilitate targeted immune-mediated cell death.