Synthesis and Evaluation of Glycoconjugates Comprising N-Acyl-Modified Thomsen-Friedenreich Antigens as Anticancer Vaccines

Thomsen-Friedenreich (TF) antigen is an important tumor-associated carbohydrate antigen. Its low immunogenicity, however, limits its application in the development of anticancer vaccines. To solve this problem, several N-acyl-modified TF derivatives were synthesized and conjugated with carrier protein CRM197 (a mutated diphtheria toxoid cross-reactive material). The immunological results in BALB/c mice demonstrated that these modified TF antigen conjugates could stimulate the production of higher titers of IgG antibodies that cross-reacted with native TF antigen. These glycoconjugates showed strong lymphocyte proliferative response, suggesting that they can induce cellular immunity. Furthermore, the elicited antisera reacted strongly with TF-positive tumor cells (4T1). In particular, the N-monofluoroacetyl-modified TF conjugate 4-CRM197 showed the strongest complement-dependent cytotoxicity effect against 4T1 cells, implying the potential of this glycoconjugate as an anticancer vaccine.