A fully synthetic glycopeptide antitumor vaccine based on multiple antigen presentation on a hyperbranched polymer.

For antitumor vaccines both the selected tumor-associated antigen, as well as the mode of its presentation, affect the immune response. According to the principle of multiple antigen presentation, a tumor-associated MUC1 glycopeptide combined with the immunostimulating T-cell epitope P2 from tetanus toxoid was coupled to a multi-functionalized hyperbranched polyglycerol by "click chemistry". This globular polymeric carrier has a flexible dendrimer-like structure, which allows optimal antigen presentation to the immune system. The resulting fully synthetic vaccine induced strong immune responses in mice and IgG antibodies recognizing human breast-cancer cells.

Immunogenicity of a Fully Synthetic MUC1 Glycopeptide Antitumor Vaccine Enhanced by Poly(I:C) as a TLR3-Activating Adjuvant.

Fully synthetic MUC1 glycopeptide antitumor vaccines have a precisely specified structure and induce a targeted immune response without suppression of the immune response when using an immunogenic carrier protein. However, tumor-associated aberrantly glycosylated MUC1 glycopeptides are endogenous structures, “self-antigens”, that exhibit only low immunogenicity. To overcome this obstacle, a fully synthetic MUC1 glycopeptide antitumor vaccine was combined with poly(inosinic acid:cytidylic acid), poly(I:C), as a structurally defined Toll-like receptor 3 (TLR3)-activating adjuvant. This vaccine preparation elicited extraordinary titers of IgG antibodies which strongly bound human breast cancer…

A Fully Synthetic Four-Component Antitumor Vaccine Consisting of a Mucin Glycopeptide Antigen Combined with Three Different T-Helper-Cell Epitopes

In a new concept of fully synthetic vaccines, the role of T-helper cells is emphasized. Here, a synthetic antitumor vaccine consisting of a diglycosylated tumor-associated MUC1 glycopeptide as the B-cell epitope was covalently cross-linked with three different T-helper-cell epitopes via squaric acid ligation of two linear (glyco)peptides. In mice this four-component vaccine administered without external immune-stimulating promoters elicit titers of MUC1-specific antibodies that were about eight times higher than those induced by a vaccine containing only one T-helper-cell epitope. The promising results indicate that multiple activation of different T-helper cells is useful for applications …

Synthetic Antitumor Vaccines Through Coupling of Mucin Glycopeptide Antigens to Proteins

The requirements for coupling reactions of carbohydrate molecules very much depend upon the biological recognition processes that should be investigated and upon the target structures of the desired carbohydrate ligand. If the carbohydrate conjugate itself is the recognized ligand, as for example, the binding site of a P-selectin ligand comprising sialyl-LewisX and a specific peptide sequence, the natural glycoside bond must be installed. A stereoselective and regioselective block glycosylation between a sialyl-LewisX trichloroacetimidate and a partially deprotected Thomsen–Friedenreich antigen derivative was developed to achieve this aim. In contrast, the coupling reactions by which glycop…

ChemInform Abstract: Mucin Glycopeptide-Protein Conjugates - Promising Antitumor Vaccine Candidates

Recent efforts towards the development of synthetic glycopeptide vaccines, which aim at the active immunization of patients against their own tumor tissues, are outlined. To achieve sufficient tumor selectivity, glycopeptides of the tandem repeat region of tumor-associated mucin, MUC1, have been synthesized. Since the endogenous structures usually exert low immunogenicity, these glycopeptide antigens, as B-cell epitopes, were conjugated with immunostimulating components. In the present short review, work is outlined in which the MUC1 B-cell epitope peptides are conjugated with bovine serum albumin (BSA), keyhole limpet hemocyanin (KLH), or tetanus toxoid (TTox). In particular, the synthetic…

A Synthetic MUC1 Anticancer Vaccine Containing Mannose Ligands for Targeting Macrophages and Dendritic Cells

A MUC1 anticancer vaccine equipped with covalently linked divalent mannose ligands was found to improve the antigen uptake and presentation by targeting mannose-receptor-positive macrophages and dendritic cells. It induced much stronger specific IgG immune responses in mice than the non-mannosylated reference vaccine. Mannose coupling also led to increased numbers of macrophages, dendritic cells, and CD4+ T cells in the local lymph organs. Comparison of di- and tetravalent mannose ligands revealed an increased binding of the tetravalent version, suggesting that higher valency improves binding to the mannose receptor. The mannose-coupled vaccine and the non-mannosylated reference vaccine ind…

Synthetic MUC1 Antitumor Vaccine with Incorporated 2,3-Sialyl-T Carbohydrate Antigen Inducing Strong Immune Responses with Isotype Specificity

The endothelial glycoprotein MUC1 is known to underlie alterations in cancer by means of aberrant glycosylation accompanied by changes in morphology. The heavily shortened glycans induce a collapse of the peptide backbone and enable accessibility of the latter to immune cells, rendering it a tumor-associated antigen. Synthetic vaccines based on MUC1 tandem repeat motifs, comprising tumor-associated 2,3-sialyl-T antigen, conjugated to the immunostimulating tetanus toxoid, are reported herein. Immunization with these vaccines in a simple water/oil emulsion produced a strong immune response in mice to which stimulation with complete Freund's adjuvant (CFA) was not superior. In both cases, high…

Eine vollsynthetische Vier-Komponenten-Antitumor-Vakzine mit einem MUC1-Glycopeptid und drei verschiedenen T-Helferzell- Epitopen

In einem neuen Konzept fur vollsynthetische Vakzine wird die Rolle von T-Helferzellen hervorgehoben. In einer solchen synthetischen Antitumor-Vakzine wurde ein zweifach glycosyliertes tumorassoziiertes MUC1-Glycopeptid als B-Zellepitop mit drei verschiedenen T-Helferzell-Epitopen durch Quadratsaurekonjugation zweier linearer (Glyco)Peptide kovalent verknupft. In Mausen loste die Impfung mit dieser Vier-Komponenten-Vakzine ohne zusatzliche Immunstimulantien etwa achtmal hohere MUC1-spezifische Antikorpertiter aus als eine Vakzine, die nur ein T-Helferzell-Epitop enthielt. Diese ermutigenden Ergebnisse zeigen, dass die gleichzeitige Aktivierung von T-Helferzellen verschiedener Spezifitat nutz…

ChemInform Abstract: Tumor-Associated Glycopeptide Antigens and Their Modification in Anticancer Vaccines

Immunization with a Synthetic Human MUC1 Glycopeptide Vaccine against Tumor-Associated MUC1 Breaks Tolerance in Human MUC1 Transgenic Mice.

Breaking tolerance is crucial for effective tumor immunotherapy. We showed that vaccines containing tumor-associated human MUC1 glycopeptides induce strong humoral antitumor responses in mice. The question remained whether such vaccines work in humans, in systems where huMUC1 is a self-antigen. To clarify the question, mice transgenic in expressing huMUC1, mimicking the self-tolerant environment, and wild-type mice were vaccinated with a synthetic vaccine. This vaccine comprised STn and Tn antigens bound to a MUC1 tandem repeat peptide coupled to tetanus toxoid. The vaccine induced strong immune responses in wild-type and huMUC1-transgenic mice without auto-aggressive side effects. All anti…

Enhanced immunogenicity of multivalent MUC1 glycopeptide antitumour vaccines based on hyperbranched polymers.

Enhancing the immunogenicity of an antitumour vaccine still poses a major challenge. It depends upon the selected antigen and the mode of its presentation. We here describe a fully synthetic antitumour vaccine, which addresses both aspects. For the antigen, a tumour-associated MUC1 glycopeptide as B-cell epitope was synthesised and linked to the immunostimulating T-cell epitope P2 derived from tetanus toxoid. The MUC1-P2 conjugate is presented multivalently on a hyperbranched polyglycerol to the immune system. In comparison to a related vaccine of lower multivalency, this vaccine exposing more antigen structures on the hyperbranched polymer induced significantly stronger immune responses in…

CpG-Loaded Multifunctional Cationic Nanohydrogel Particles as Self-Adjuvanting Glycopeptide Antitumor Vaccines

Self-adjuvanting antitumor vaccines by multifunctional cationic nanohydrogels loaded with CpG. A conjugate consisting of tumor-associated MUC1-glycopeptide B-cell epitope and tetanus toxin T-cell epitope P2 is linked to cationic nanogels. Oligonucleotide CpG complexation enhances toll-like receptor (TLR) stimulated T-cell proliferation and rapid immune activation. This co-delivery promotes induction of specific MUC1-antibodies binding to human breast tumor cells without external adjuvant.

Mucin Glycopeptide-Protein Conjugates - Promising Antitumor Vaccine Candidates

Recent efforts towards the development of synthetic glycopeptide vaccines, which aim at the active immunization of patients against their own tumor tissues, are outlined. To achieve sufficient tumor selectivity, glycopeptides of the tandem repeat region of tumor-associated mucin, MUC1, have been synthesized. Since the endogenous structures usually exert low immunogenicity, these glycopeptide antigens, as B-cell epitopes, were conjugated with immunostimulating components. In the present short review, work is outlined in which the MUC1 B-cell epitope peptides are conjugated with bovine serum albumin (BSA), keyhole limpet hemocyanin (KLH), or tetanus toxoid (TTox). In particular, the synthetic…