Synthetic Multivalent Glycopeptide-Lipopeptide Antitumor Vaccines: Impact of the Cluster Effect on the Killing of Tumor Cells

Multivalent synthetic vaccines were obtained by solid-phase synthesis of tumor-associated MUC1 glycopeptide antigens and their coupling to a Pam(3)Cys lipopeptide through click reactions. These vaccines elicited immune responses in mice without the use of any external adjuvant. The vaccine containing four copies of a MUC1 sialyl-T-N antigen showed a significant cluster effect. It induced in mice prevailing IgG(2a) antibodies, which bind to MCF-7 breast tumor cells and initiate the killing of these tumor cells by activation of the complement-dependent cytotoxicity complex.