DNA vaccines suppress tumor growth and metastases by the induction of anti-angiogenesis.

Four novel oral DNA vaccines provide long-lived protection against melanoma, colon, breast, and non-small cell lung carcinoma in mouse model systems. The vaccines are delivered by attenuated Salmonella typhimurium to secondary lymphoid organs and are directed against targets such as carcinoembryonic antigen, tyrosine-related protein, vascular endothelial growth factor receptor-2 [also called fetal liver kinase-1 (FLK-1)], and transcription factor Fos-related antigen-1 (Fra-1). The FLK-1 and Fra-1 vaccines are effective in suppressing angiogenesis in the tumor vasculature. All four vaccines are capable of inducing potent cell-mediated protective immunity, breaking peripheral T-cell tolerance against these self-antigens resulting in effective suppression of tumor growth and metastasis. It is anticipated that such research efforts will contribute toward the rational design of future DNA vaccines that will be effective for prevention and treatment of human cancer.