Synthesis of Fluorinated Tyr-GalNAc Antigens and Potent Antitumor Activity of Their Bacteriophage Qβ Conjugates

Abstract Tumor-associated carbohydrate antigens (TACAs) are promising targets for cancer immunotherapy but are limited by poor immunogenicity and antigen instability. Here, we report a vaccine lead platform targeting the noncanonical TACA GalNAcα-O-tyrosine (Tyr-GalNAc). To enhance antigen performance, fluorine atoms were introduced at the N-acetyl methyl group or the C6 position of the GalNAc moiety, and the resulting glycoepitopes were displayed on bacteriophage Qβ virus-like particles (VLPs) to enable dense multivalent presentation. The leading constructs, Qβ-Tyr-GalNFAc and Qβ-Tyr-GalNF2Ac, elicited strong T-cell-dependent IgG responses and antibodies that recognize native Tyr-GalNAc on tumor cells. These antibodies mediated potent complement-dependent cytotoxicity and antibody-dependent cellular phagocytosis in vitro. In vivo, vaccination conferred significant tumor protection in prophylactic models, with improved survival and partial long-term tumor control. This work identifies fluorinated Tyr-GalNAc as a promising antigen and demonstrates that rational glycan engineering combined with VLP display enhances functional antitumor immunity.