Novel tumor-associated proximity antigen pair (TAPA)

The term Novel tumor-associated proximity antigen pair refers to a therapeutic strategy rather than a single molecular entity. It describes a combinatorial targeting approach where two different antigens (e.g., CD19 and CD22, or HER2 and MUC1) must be present in close proximity on the surface of a single cancer cell to trigger the activity of a drug, such as a logic-gated CAR-T cell or a proximity-activated bispecific antibody. This method is designed to enhance tumor specificity and reduce 'on-target, off-tumor' toxicities by ensuring that the treatment only attacks cells expressing the specific combination of markers, which is ideally unique to the malignancy. Because this is a conceptual framework for target selection in immunotherapy, it does not have a single canonical protein structure but represents an emerging class of precision oncology targets.

Other names

Tumor-associated proximity antigenProximity-dependent antigen pairLogic-gated antigen pairCombinatorial antigen target

Proximity-based activation (e.g., AND-gate logic) where a therapeutic effect is only triggered when two distinct antigens are expressed in close proximity on the same cell surface.