Tumor antigen

VIB-RUG Department of Molecular Biomedical Research

Molecular ImmunoBiotechnology Unit

What are tumor associated antigens (TAA)?

Cancer cells originate from normal cells ("self"), and mutate to become insensitive to normal growth control, to become immortal, to be able to invade surrounding tissue and to be able to form metastases at a distant place. The development of cancer takes a long time (up to 20 years). This is explained by the fact that the development of the cancer cell requires multiple events (mutations) to take place. Several genes are known that, when mutated, give a higher chance of developing cancer. But this mutagenesis is not specific for these genes: the mutations accumulate random in the pre-cancer cell genome. From time to time, a cell arises with a mutation that gives it one of the traits needed to become a cancer cell. These cells survive since they have a selective advantage over cells with other mutations (at least short term).

So cancer cells have accumulated mutations that are possibly recognized as non-self by the immune system. These mutations are different for each tumor. Sometimes, these mutations trigger an immune response. We will refer to these antigens as Specific Tumor Antigens (STA). STAs can be derived from intracellular or extracellular proteins, and can be presented in a way that they can be recognized by T-cells.

Also, cancer cells often produce much more of certain normal receptors, or produce them in a different way (e.g. different glycosylation). These antigens are sometimes common in a certain subpopulation of tumors. We will refer to these antigens as Common Tumor Antigens (CTA). CTAs can be used as a marker to categorize the tumor, or to monitor disease progression. Usually, a CTA is exposed to the extracellular environment and can be recognized by antibodies.