Enhancement of the Immunogenicity of Synthetic Carbohydrate Vaccines by Chemical Modifications of STn Antigen

The abnormal glycans expressed on the surface of tumor cells, known as tumor-associated carbohydrate antigens, increase the chance to develop carbohydrate-based anticancer vaccines. However, carbohydrate antigens pose certain difficulties, and the major drawback is their weak immunogenicity. To tackle this problem, numerous structurally modified STn antigens were designed and synthesized in this work. These synthetic antigens were screened in vitro by using competitive ELISA method, and the antigens with positive response were conjugated to the protein carrier for vaccination. The vaccination results on mice showed that some fluorine-containing modifications on the STn antigen can significantly increase the anti-STn IgG titers and improve the ratios of anti-STn IgG/IgM. The antisera can recognize the tumor cells expressing the native STn antigen.