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A “shot in the arm” for cancer therapy: Coupling of synthetic glycopeptide tandem‐repeat sequences of the epithelial mucin MUC1 with the Thomsen–Friedenreich (T) antigen (A) or a difluoro analogue (B) to tetanus toxoid (TTox) affords synthetic vaccines, which induce very strong immune responses in mice overriding the natural tolerance of the immune system. The induced antibodies are selectively directed against the tumor‐associated MUC1 structures and strongly bind to breast cancer cells of the MCF‐7 cell line.

A shot in the arm for cancer treatment: two MUC1 tetanus toxoid vaccines were synthesized and induced a strong immune response in mice. The antibodies elicited by the vaccines show a high selectivity for the tumor cells in mammary carcinoma tissues and also distinguish between tumor tissues at different stages.

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The membrane-bound mucin glycoprotein MUC1 is extensively overexpressed on epithelial tumor cells and considered an attractive target in the development of cancer immunotherapy and immunodiagnostics. In epithelial tumors downregulation of glycosyltransferases, in particular the core 2 b-1,6-N-acetylglucosaminyltransferase, and up-regulation of sialyltransferases results in the formation of short saccharides with premature sialylation of the extracellular domain of mucins, [1][2][3][4] exposure of the peptide backbone of these otherwise heavily glycosylated proteins, and formation of a tumor-associated epitope consisting of both the saccharide and the peptide structure.[5]The MUC1 extracellular domain consists of numerous tandem repeats of the sequence HGVTSAPDTRPAPG-STAPPA which embodies five potential glycosylation sites (Scheme 1 a). The development of synthetic vaccines based on the exposed MUC1-tandem-repeat peptide backbone, the tumor associated glycans, such as T N , T, sialyl-T N , sialyl-T, and recent tandem-repeat glycopeptides has been the subject of intensive research efforts. [6][7][8][9] Such vaccines need to induce a specific immune response, which leads to the formation of antibodies that differentiate between normal and cancer epithelial cells. This requirement and the substantial effort required to synthesize and conjugate the carbohydrate and glycopeptide antigens call for the development of miniaturized analytical technologies which allow rapid and reliable mapping of antibody specificity. The immobilization of biomolecules such as peptides, [10][11][12][13] oligonucleotides, [14,15] carbohydrates, [16][17][18] and proteins [10,[19][20][21] in microarray formats and their use in bioassays has proven to be a very valuable, time-and material-saving methodology; it is also a viable alternative to the established solution-phase bioassays, such as the ELISA-based formats. Herein we report on the development of a microarray platform for mapping the specificity of antibodies raised against tumor-associated mucin MUC1 glycopeptides. (for previous work on glycopeptide microarrays see reference [22]).Recently, we synthesized vaccine constructs consisting of sialyl-T N -and T N -20-mer tandem-repeat MUC1 glycopeptides connected to a T H -cell peptide epitope from ovalbumin (OVA [323][324][325][326][327][328][329][330][331][332][333][334][335][336][337][338][339] ). Immunization of transgenic mice whose T cells express a receptor recognizing the OVA 323-339 T-cell epitope, induced a humoral immune response, [6] thereby leading to the formation of antibodies directed against the MUC1 glycopeptide B-cell epitope. To evaluate the specificity of these antibodies we have now synthesized a number of MUC1 glycopeptides having variations in the glycan structure, the glycan position on the tandem-repeat peptide, and the number of tandem repeats or shorter peptides excluding parts of the repeat (Scheme 1 b and Scheme 2); for a description of the synthesis see the Supporting Information). These glycopeptides were equ...