Synthetic, peptide-based, self-adjuvanting vaccines based on the cancer-related MUC1 antigen, a T-helper epitope and a saponin immunoadjuvant (#68)
Tumor-associated mucin-1 (TA-MUC1) is a key target for therapeutic anticancer vaccine development, but subunit vaccines based on such weakly immunogenic glycopeptide antigens require immunopotentiating approaches to generate optimal immune responses. An emerging but underexploited strategy involves the design of unimolecular self-adjuvanting vaccine constructs that do not need to be conjugated to carrier proteins or coadministered with external adjuvants [1]. Herein, we report the synthesis, immune-evaluation in mice, and NMR studies of new, self-adjuvanting, and self-assembling tricomponent vaccines based on TA-MUC1 (glyco)peptide antigens covalently linked to a saponin immunoadjuvant and a helper T-cell peptide epitope [2]. These candidates were synthesized from unprotected building blocks in high yields using a modular chemoselective approach that harnessed two distal attachment points on the adjuvant platform to conjugate the respective peptide elements via orthogonal ligations. In mouse immunizations, the tricomponent constructs induced significant IgG antibodies that recognized the native antigen on MCF7 cancer cells, unlike dicomponent or unconjugated combinations of the corresponding invididual components. By NMR, these immunogenic candidates were shown to self-assemble into stably organized, particulate aggregates that displayed the more hydrophilic TA-MUC1 moiety on the surface and were not disrupted upon dilution. The observed correlation between higher molecular organization, structural stability and increased immunogenicity suggests a longer half-life and enhanced antigen multivalent presentation of these conjugates in physiological media, which together with the modularity and streamlined nature of synthetic strategy, makes these self-adjuvanting tricomponent vaccines as promising candidates for further development.
- Nat Rev Chem. 2021, 5, 197-216. doi: 10.1038/s41570-020-00244-3. Pifferi C, Fuentes R, Fernández-Tejada A.
- Chem Sci. 2023, 14, 3501-3513. doi: 10.1039/d2sc05639a. Pifferi C, Aguinagalde L, Ruiz-de-Angulo A, Sacristán N, Baschirotto PT, Poveda A, Jiménez-Barbero J, Anguita J, Fernández-Tejada A.