Synthesis of Azido-Globo H Analogs for Immunogenicity Evaluation

Chiang-Yun Chen; Yu-Wei Lin; Szu-Wen Wang; Yung-Chu Lin; Yang-Yu Cheng; Chien-Tai Ren; Chi-Huey Wong; Chung-Yi Wu

doi:10.1021/acscentsci.1c01277

Synthesis of Azido-Globo H Analogs for Immunogenicity Evaluation

ACS Cent Sci. 2022 Jan 26;8(1):77-85. doi: 10.1021/acscentsci.1c01277. Epub 2021 Dec 21.

Authors

Chiang-Yun Chen^{1

2

3}, Yu-Wei Lin¹, Szu-Wen Wang^{1

4}, Yung-Chu Lin¹, Yang-Yu Cheng^{1

5}, Chien-Tai Ren¹, Chi-Huey Wong^{1

2

4

6}, Chung-Yi Wu^{1

2}

Affiliations

¹ Genomics Research Center, Academia Sinica, Taipei 115, Taiwan.
² Chemical Biology and Molecular Biophysics, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan.
³ Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan.
⁴ Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan.
⁵ Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 112, Taiwan.
⁶ Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States.

Abstract

Globo H (GH) is a tumor-associated carbohydrate antigen (TACA), and GH conjugations have been evaluated as potential cancer vaccines. However, like all carbohydrate-based vaccines, low immunogenicity is a major issue. Modifications of the TACA increase its immunogenicity, but the systemic modification on GH is challenging and the synthesis is cumbersome. In this study, we synthesized several azido-GH analogs for evaluation, using galactose oxidase to selectively oxidize C6-OH of the terminal galactose or N-acetylgalactosamine on lactose, Gb3, Gb4, and SSEA3 into C6 aldehyde, which was then transformed chemically to the azido group. The azido-derivatives were further glycosylated to azido-GH analogs by glycosyltransferases coupled with sugar nucleotide regeneration. These azido-GH analogs and native GH were conjugated to diphtheria toxoid cross-reactive material CRM197 for vaccination with C34 adjuvant in mice. Glycan array analysis of antisera indicated that the azido-GH glycoconjugate with azide at Gal-C6 of Lac (1-CRM197) elicited the highest antibody response not only to GH, SSEA3, and SSEA4, which share the common SSEA3 epitope, but also to MCF-7 cancer cells, which express these Globo-series glycans.