Taas

Tumor-associated antigens (TAAs) are proteins or peptides expressed by cancer cells and recognizable by the immune system, while also being present in some normal tissues. TAAs are distinguished from tumor-specific antigens (TSAs), which arise from tumor-specific mutations and are not found in normal tissues. TAAs typically arise through overexpression of normal proteins, aberrant expression of differentiation antigens, or ectopic expression of antigens normally restricted to reproductive tissues or embryonic development.

TAAs can be categorized into several groups. Overexpressed self-antigens include proteins such as HER2/neu, MUC1, and EGFR. Differentiation antigens are lineage-specific proteins normally present in healthy cells of a given tissue, such as Melan-A/MART-1 or Tyrosinase in melanocytes. Cancer-testis antigens (CTAs) like NY-ESO-1 and the MAGEA family are normally restricted to testis and placenta but are aberrantly expressed in various tumors. Other TAAs include embryonic or tissue-restricted proteins and cancer stem cell markers, as well as telomerase components like hTERT, which are reactivated in many cancers.

TAAs have been explored as targets for cancer immunotherapy. Approaches include peptide and protein vaccines, dendritic cell–based vaccines, and adoptive T cell therapies directed against TAAs. Checkpoint inhibitors can enhance responses to TAAs by relieving T cell inhibition. Challenges include limited immunogenicity, tumor heterogeneity, immune tolerance, and the risk of autoimmunity due to expression of the same antigens in some normal tissues.

Identification of TAAs relies on expression profiling, serological screening (serology-assisted discovery), and immunopeptidomics to identify peptides presented by HLA molecules. TAAs remain a focus of research to improve specificity and safety while enabling effective immune responses against tumors.