Tumor antigen (TA) (TA)

Tumor antigens are molecules, primarily proteins or peptides, that are expressed by cancer cells and can be recognized by the immune system [NCI, 2023]. They are broadly categorized into tumor-associated antigens (TAAs), which are overexpressed or inappropriately expressed self-proteins, and tumor-specific antigens (TSAs) or neoantigens, which arise from non-synonymous somatic mutations unique to the tumor [Nature Reviews Cancer, 2018]. These antigens are presented on the cell surface either as intact proteins or as degraded peptide fragments bound to Major Histocompatibility Complex (MHC) molecules. In modern oncology, they serve as the fundamental targets for immunotherapies such as CAR-T cells, bispecific T-cell engagers (BiTEs), and cancer vaccines, which aim to direct cytotoxic T-cells to eliminate malignant cells [Science, 2015]. The effectiveness of targeting these antigens depends on their specificity to the tumor and the density of their expression on the cell surface. However, therapeutic challenges include "antigen escape," where tumors lose the target antigen to evade immune pressure, and "on-target off-tumor" toxicity, where the therapy attacks healthy tissues expressing the same antigen [Journal of Clinical Oncology, 2020].

Other names

Tumor-associated antigen (TAA)Tumor-specific antigen (TSA)NeoantigenCancer-testis antigen (CTA)Oncofetal antigenTumor-restricted antigen

Therapeutic agents target tumor antigens through direct binding by antibodies, recognition by engineered T-cell receptors (TCRs) or chimeric antigen receptors (CARs), or by priming the endogenous immune system via vaccines to recognize peptide-MHC complexes, leading to selective destruction of antigen-expressing malignant cells [NCI, 2023; Science, 2015].