Table 1.

Selected Tumor Escape Mechanisms.

Mechanism	Basis of Escape Mechanism
Ignorance	Lack of danger signals
	Decreased neoantigen burden
Impaired antigen presentation	Mutation or downregulation of tumor antigens
	Mutation or downregulation of MHC genes
Expression of immunosuppressive molecules	Cytokines (TGF-β, IL-10, VEGF, prostaglandins, etc)
	Checkpoint proteins (PD-1, CTLA-4, TIM-3, LAG-3, etc)
	Indolamine 2,3-diooxygenase (IDO)
Tolerance induction	Regulatory T cells and MDSCs
	Mitigation of pro-inflammatory cytokine secretion

Abbreviations: TGF-β, transforming growth factor-β; VEGF, IL-10, interleukin-10; vascular endothelial growth factor; MDSCs, myeloid-derived suppressor cells.