Tumor‐associated carbohydrate antigens: A possible avenue for cancer prevention

Here we examine the use of glycopeptides containing tumour‐associated carbohydrate antigens (TACA) as potential preventive vaccines for carcinomas. Our recent results suggest that CD8+ T cells (CTL) are capable of recognizing TACA in a conventional class I MHC‐restricted fashion. The Thomsen–Friedenreich antigen (TF), a disaccharide, and Tn, its immediate precursor, are TACA largely expressed in carcinomas. TF and Tn can be successfully used as Th‐independent vaccines when conjugated to designer peptides with optimal binding affinity for class I MHC molecules. TF‐ and Tn‐specific CTL generated using this strategy are capable of recognizing TACA‐expressing tumours in vitro, suggesting that glycopeptides are as effectively presented by class I MHC molecules as non‐glycosylated peptides. Because the exact sequences of endogenously synthesized glycopeptides are unknown, the TACA‐specific T cell repertoire elicited by carbohydrate‐based vaccines is assumed to be degenerate. Here we report that mice genetically manipulated to develop TACA‐expressing mammary tumours are not tolerant to glycopeptide vaccination. Moreover, we tested the immunogenicity of designer glycopeptides capable of binding multiple HLA alleles as a novel approach for the development of vaccines potentially useful for vaccination of a large fraction of the general population. Our results have suggested that CTL derived from normal donors respond with high efficiency to glycopeptides in vitro, opening a new avenue for the design of prospective vaccines for cancer prevention.