Abstract 1588: Using glyco-engineered cells with flexible expression of tumor-associated carbohydrates for the generation of highly tumor-specific antibodies
Authors: Kehler Patrik , Kast Naomi , Weiske Manon , Gurka Stephanie , Lischke Timo , Gellert Johanna , Danielczyk Antje 
Published: June 2023

Abstract
Introduction: Highly potent therapeutic approaches require clean targets. However, the majority of antibodies in clinical development or approved for cancer therapy address protein targets that are only over-expressed in cancer and yet often show significant expression in healthy organs. Besides protein expression, glycosylation is strongly altered in cancer, reflecting changes in tumor metabolism or genetic alterations. Mutated or mislocated glycosyltransferases, glycosidases, substrates and chaperones, give rise to tumor-associated, truncated O-glycans like Thomsen-Friedenreich (TF) or Thomsen novelle (Tn) which are expressed on proteins in different carcinomas, leukemias, lymphomas and their metastases. Due to the heterogeneous nature of glycan biosynthesis, variations of glycan-structure occur at a given site of a glycoprotein, making fine-tuning of antibodies against a specific glycoprotein challenging. Therefore, Glycotope developed a cell line based platform, able to express proteins carrying distinct tumor-related glycan-structures in order to generate highly tumor-specific protein/carbohydrate combined epitope binding antibodies, thus increasing tumor selectivity of protein targeting antibodies.
Experimental procedures: The presence of tumor-associated carbohydrates in cancer tissues was demonstrated by immunohistochemistry analysis. A platform comprising different glyco-engineered cell lines capable to express proteins with distinct glycoforms was developed and fully characterized. The cells’ ability to express specific protein/carbohydrate combined epitopes (GlycoTargets) with distinct carbohydrates was shown by flow cytometry, ELISA and mass spectrometry experiments. The versatile use of the platform for i) recombinant expression of GlycoTargets for the use as immunogens, ii) screening tool in antibody discovery campaigns, iii) characterization of antibody lead candidates, was shown in ELISA and flow cytometry experiments.
Results: Using our glyco-engineered cells, we showcase the potential of the platform as a tool for the generation of proteins with specific glycosylation and for screening of antibodies that bind to their target protein only in combination with a specific tumor-associated glycan structure.
Conclusion: Our platform enables tailored immunization and screening approaches in order to generate antibodies against specific protein/carbohydrate combined epitopes. These antibodies bind their protein target only in presence of tumor-associated carbohydrates, thereby showing markedly reduced binding to the protein expressed in healthy tissues. This cell-based platform provides the basis for target validation, antigen production, immunization and screening for highly specific antibodies, opening the field for more effective therapeutic approaches.
Citation Format: Patrik Kehler, Naomi Kast, Manon Weiske, Stephanie Gurka, Timo Lischke, Johanna Gellert, Antje Danielczyk. Using glyco-engineered cells with flexible expression of tumor-associated carbohydrates for the generation of highly tumor-specific antibodies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1588.