Immunogenicity Study of Globo H Analogues with Modification at the Reducing or Nonreducing End of the Tumor Antigen

Abstract

Globo H-based therapeutic cancer vaccines have been tested in clinical trials for the treatment of late stage breast, ovarian, and prostate cancers. In this study, we explored Globo H analogue antigens with an attempt to enhance the antigenic properties in vaccine design. The Globo H analogues with modification at the reducing or nonreducing end were synthesized using chemoenzymatic methods, and these modified Globo H antigens were then conjugated with the carrier protein diphtheria toxoid cross-reactive material (CRM) 197 (DT), and combined with a glycolipid C34 as an adjuvant designed to induce a class switch to form the vaccine candidates. After Balb/c mice injection, the immune response was studied by a glycan array and the results showed that modification at the C-6 position of reducing end glucose of Globo H with the fluoro, azido, or phenyl group elicited IgG antibody response to specifically recognize Globo H (GH) and the GH-related epitopes, stage-specific embryonic antigen 3 (SSEA3) (also called Gb5) and stage-specific embryonic antigen 4 (SSEA4). However, only the modification of Globo H with the azido group at the C-6 position of the nonreducing end fucose could elicit a strong IgG immune response. Moreover, the antibodies induced by these vaccines were shown to recognize GH expressing tumor cells (MCF-7) and mediate the complement-dependent cell cytotoxicity against tumor cells. Our data suggest a new potential approach to cancer vaccine development.

Carbohydrate‐based vaccines for oncotherapy

“…And the analogues were conjugated with diphtheria toxoid cross‐reactive material (CRM) 197 (DT) as protein carrier and a glycolipid C34 as adjuvant. However, only the modification of Globo H with the azido group at the C‐6 position of the nonreducing end of fucose could elicit a strong IgG immune response . Our group also developed a series of cross‐reactivity‐based modified cancer vaccines.…”

“…However, only the modification of Globo H with the azido group at the C-6 position of the nonreducing end of fucose could elicit a strong IgG immune response. 199 Our group also developed a series of cross-reactivity-based modified cancer vaccines. Early in 2010, we reported the synthesis of more than 40 structurally modified STn antigens, and the fluorine-containing modifications on the STn antigens conjugated to KLH displayed outstanding results with 3∼5 times higher and cross-reactive antibody titers in mice than those of natural STn-KLH.…”

Glycan Arrays: From Basic Biochemical Research to Bioanalytical and Biomedical Applications

“…Coupling is usually performed at slightly alkaline conditions (a pH of approximately 8.5) and remaining functional groups are quenched with an alkaline ethanolamine solution, therefore, attention has to be maintained with regard to functional groups on glycans prone to alkaline hydrolysis. The reliable amine/NHS coupling is the routine immobilization chemistry in many laboratories (18,24,39,40). Recently, it has been shown that the commonly used NHS hydrogel slides retain polysaccharides that are not amine functionalized, allowing immobilization of activated small glycans and unmodified polysaccharides on the same surface (13,39).…”

“…Based on these results, clinical trials with this new vaccine candidate are planned (130). Chemically modified analogs of Globo-H were tested as conjugates with the same carrier protein and adjuvant with the aim to further improve immunogenicity leading to the identification of an oligosaccharide containing an azide modification at the C6 of the terminal fucose (40). Aberrant regulation of glycosyltransferases in the O-glycosylation machinery creates TACAs that are fragments of normal O-glycans, such as the Thomsen-Friedenreich [TF; β-Gal(1→3)α-GalNAc(1→)Ser/Thr] or the Thomsen-nouvelle [Tn; α-GalNAc(1→)Ser/Thr] antigens (129).…”

Interrogation of side chain biases for oligomannose recognition by antibody 2G12 via structure-guided phage display libraries

“…Subtle changes in glycan composition of cellular surfaces can signal significant biological transitions, for example tumor metastasis 3 . However, detection and therapeutic targeting of such biologically important glycan changes is largely limited by a lack of specific and high-affinity binding reagents.…”