Table 1.

Major advantages and remaining challenges for tumor antigens.

Tumor antigens		Advantages	Challenges
Subunit antigens	Polysaccharides	Defined chemical synthesis	Elicitation of humoral rather than cellular immune responses
	Peptides	Ease of production	Poor delivery efficiency
		Stable vaccine formulations	Monovalent immune response
		May not require antigen-processing by APCs	Subject to HLA-specificity
	Proteins	Broad-epitope immune responses Wide HLA-specificity	Poor delivery efficiency
			Suboptimal for CD8+ T cell responses
			Weak immunogenicity of self-antigens
	DNA and mRNA	Ease of production	Poor delivery efficiency
		In situ expression of full-length antigens	Poor in vivo stability
		Flexible to encode immune stimulators	Limited transfection efficiency
Whole-cell antigens	Tumor-cell lysate	Broad-epitope immune responses Potential for “personalized” therapy	Requires tissue biopsy
			Manufacturing challenges
			Loss of antigenicity during production
			Presence of self-antigens
	Immunogenically dying tumor cells	Broad-epitope immune responses	Requires additional therapeutic interventions Presence of self-antigens and immunosuppressive molecules, e.g., PD-L1
		Full preservation of tumor antigens
		Potential for “personalized” therapy