Tumor-associated antigens and pathogen antigens (TAA/PA)

Tumor-associated antigens (TAAs) and pathogen antigens are molecular markers expressed by diseased cells that distinguish them from healthy host tissue. TAAs include proteins that are overexpressed (e.g., HER2), lineage-specific (e.g., CD20), or neoantigens resulting from somatic mutations [National Cancer Institute, 2023]. Pathogen antigens are foreign proteins derived from viruses, bacteria, or parasites that are presented on the surface of infected cells, often in the context of Major Histocompatibility Complex (MHC) molecules [Janeway's Immunobiology, 2017]. These antigens serve as the fundamental targets for immunotherapies, including monoclonal antibodies, chimeric antigen receptor (CAR) T-cells, and therapeutic vaccines. By binding to these antigens, drugs can trigger direct apoptosis, neutralize signaling pathways, or recruit immune effector cells to destroy the target cell [Nature Reviews Cancer, 2021]. A significant challenge in targeting TAAs is the risk of "on-target, off-tumor" toxicity, where the immune system attacks normal cells expressing the same antigen at lower levels [Journal of Clinical Oncology, 2020]. Additionally, tumors may undergo "antigen escape," losing the target antigen to evade immune detection, which necessitates the development of multi-antigen targeting strategies [Cell, 2019].

Other names

Tumor antigensTumor-specific antigens (TSA)Cancer-testis antigens (CTA)NeoantigensViral antigensDisease-associated antigens

Targeted immune-mediated destruction of diseased cells via antibody-dependent cellular cytotoxicity (ADCC), T-cell activation, complement-dependent cytotoxicity (CDC), or direct inhibition of oncogenic signaling pathways.