Site‐specific chemoenzymatic glycoengineering of cetuximab, a therapeutic monoclonal antibody (607.16)

Abstract

IgG type monoclonal antibodies are an important class of therapeutic glycoproteins used in the treatment of a wide range of maladies: cancer, auto‐immune disorders, and infectious diseases. Cetuximab is a therapeutic monoclonal antibody, which is glycosylated at both the FAB and FC domains of the heavy chain at Asn ‐ 88 and Asn ‐ 299 respectively. The FAB glycan is composed of ca. 30% non‐human α ‐ gal and/or N‐glycolylneuramic acid (NGNA), which have been shown to cause allergic reactions in some patient populations, while the FC domain glycans are not optimal for effector functions. In this work, we perform site‐specific glycan remodeling of cetuximab by taking advantage of the substrate specificity of two endoglycosidases and their cognate glycosynthases. Endo F3, from E. meningosepticum, was initially used to remove glycans from both the FAB and FC domains. A fully galactosylated complex type glycan was precisely transferred to the FC using the glycosynthase mutant of Endo S from S. pyogenes. Finally a fully sialylated N‐glycan was added to the FAB glycosylation site using the Endo F3 glycosynthase mutant. The glyco‐reengineered cetuximab is expected to possess enhanced therapeutic efficacy without the allergic side effects. Our site‐specific glycosylation approach should be generally applicable to other therapeutic monoclonal antibodies.Grant Funding Source: NIH Grant R01 GM080374