What are tumor-associated antigens (TAAs) and neoantigens, and how do they differ?

• A. TAAs are self-antigens overexpressed in tumors; Neoantigens arise from tumor-specific mutations and are non-self.
• B. TAAs are non-self; Neoantigens are self overexpressed
• C. TAAs are bacterial antigens; Neoantigens are viral antigens
• D. TAAs are only expressed in normal tissues; Neoantigens in tumors

Answer: (A)

The main idea is that tumor antigens come from two different sources: normal proteins that are simply overexpressed in cancer cells, and new peptides created by cancer-specific mutations. Tumor-associated antigens are self-proteins that are present in normal cells but are produced at much higher levels in tumor cells. Neoantigens, on the other hand, come from mutations that occur in the tumor; these mutated peptides are new to the immune system and are perceived as non-self.

This distinction matters because T cells often show tolerance to self-proteins, so TAAs can provoke weaker immune responses. Neoantigens, being novel and not present during thymic selection, are typically more immunogenic and can drive stronger T cell responses. That’s why the best description is that tumor-associated antigens are self-derived overexpressed proteins in tumors, while neoantigens are derived from tumor-specific mutations and are non-self.