Synthetic self‐adjuvanted multivalent Mucin 1 (MUC1) glycopeptide vaccines with improved in vivo antitumor efficacy

Abstract The tumor‐associated glycoprotein Mucin 1 (MUC1) is aberrantly glycosylated on cancer cells and is considered a promising target for antitumor vaccines. The weak immunogenicity and low sequence homology of mouse mucins and human MUC1 are the main obstacles for the development of vaccines. Herein, a self‐adjuvanted strategy combining toll‐like receptor 2 lipopeptide ligands and T‐cell epitopes and the multivalent effect were used to amplify the immune response and evade the unpredictable immunogenicity, generating two self‐adjuvanted three‐component MUC1 vaccines (mono‐ and trivalent MUC1 vaccines). To simulate the aberrantly glycosylated MUC1 glycoprotein, the MUC1 tandem repeat peptide was bounded with Tn antigens at T9, S15, and T16, and served as B‐cell epitopes. Results showed that both vaccines elicited a robust antibody response in wild‐type mice compared with a weaker response in MUC1 transgenic mice. The trivalent vaccine did not elevate the antibody response level compared with the monovalent vaccine; however, a more delayed tumor growth and prolonged survival time was realized in wild‐type and transgenic mouse models treated with the trivalent vaccine. These results indicate that the self‐adjuvanted three‐component MUC1 vaccines, especially the trivalent vaccine, can trigger robust antitumor effects regardless of sequence homology, and, therefore, show promise for clinical translation.