Table 2.

Different types of tumor antigens.

	Class of tumor antigen	Description	Tumor specificity	Example of tumor antigen	References
Tumor-associated antigens (TAA)	Overexpressed antigens	Antigens overexpressed in tumor cells and normal level of expression in healthy cells	Variable	HER-2, hTERT, mesothelin, MUC-1, and p53	[16–19]
	Differentiation antigens	Antigens expressed on tumor cells and normal cells	Variable	gp100, MART-1, PSA, PAP, and tyrosinase	[20–24]
	Cancer-testis antigens	Antigens are primarily expressed on testes, fetal ovaries, and trophoblasts	High	BAGE, MAGE, GAGE, PRAME, NY-ESO-1	[25–28]
Tumor-specific antigens (TSA)	Oncogenic viral antigens	Abnormal expression in cells infected with an oncovirus	High	EBV LMP-1/LMP-2A, HPV-E6/E7, HTLV-1	[29–32]
	Tumor-specific mutated antigens	Mutations result in the generation of a new peptide. Mutations could arise at the gene level from chromosome translocations or due to posttranslational modifications	High	KRAS, NRAS, epitopes from BCR-ABL translocation, ETV6, NPM/ALK and ALK	[33]

HER-2, human epidermal growth factor receptor 2; hTERT, human telomerase reverse transcriptase; MUC-1, mucin 1; MART-1, melanoma antigen recognized by T cells; PSA, prostate-specific antigen; PAP, prostatic acid phosphatase, MAGE, melanoma antigen; NY-ESO-1, New York esophageal squamous cell carcinoma 1; GAGE, G antigen; BAGE, B melanoma antigen; EBV, Epstein–Barr virus; LMP-1, latent membrane protein 1; LMP-2A, latent membrane protein 2A; HPV, human papillomavirus; HTLV-1, human T cell lymphotropic virus type 1; KRAS, Kirsten rat sarcoma virus; NRAS, neuroblastoma RAS viral oncogene homolog; BCR, breakpoint cluster region gene; ABL, Abelson proto-oncogene; NPM, nucleophosmin; ALK, anaplastic lymphoma kinase.