Glycoengineering of antibodies to modulate immune functions

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Project Summary Antibodies are an important class of therapeutics that are widely used for treatment of cancer, autoimmune diseases, and infectious diseases. Compelling experimental data have demonstrated that Fc glycosylation is a critical structural determinant for modulating antibody’s effector functions, including antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), activation of apoptosis, and anti- inflammatory activities. However, progress in understanding the functional roles of antibody glycosylation is hampered by the tremendous structural heterogeneity of Fc glycosylation. To address this problem, we have developed a chemoenzymatic method that permits site-specific Fc and Fab glycan remodeling to generate homogeneous antibody glycoforms. In ths application, we propose to exploit the site-specific chemoenzymatic glycan remodeling method as a key platform technology to address three important questions related to antibody functions, as highlighted in the following three specific aims. Aim 1 is to understand how Fc glycosylation modulate Fc receptor binding and ADCC activity by selective modification of the core fucose, by performing structural studies, and by synthesizing novel glycoforms, coupled with Fc receptor binding and ADCC assays. Aim 2 is to evaluate how site-specific sialylation of Fc glycans affects antibody’s anti- inflammatory activity by constructing asymmetrically sialylated or multiply sialylated glycoforms, coupled with animal studies. Aim 3 is to augment antibody’s complement-dependent cytotoxicity (CDC) by constructing structurally well-defined Gal/rhamnose antigen-antibody conjugates to recruit natural IgG and IgM antibodies in circulation. These studies will yield important new knowledge in glyco-immunology, which will facilitate the development of more effective antibody-based therapeutics.