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 Pam3 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-TN antigen showed a significant cluster effect. It induced in mice prevailing IgG2a 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.