The use of mammalian expression systems results in a remarkable heterogeneity of mAb products, generally due to post-translational modifications, and glycosylation is a critical post-translation modification because it has a profound impact on the safety and efficacy of mAbs. The present study was designed to explore the impact of a different expression system on mAb N-glycosylation. The detailed structures of individual glycans between anti-EGFR monoclonal antibodies produced by different expression systems were successfully characterized at the level of free oligosaccharides using liquid chromatography electrospray ionization quadrupole time-of-fight mass spectrometry (LC-ESI-QTof MS). An alternating low and elevated collision energy scan, in source collision-induced dissociation and MS/MS in combination with exoglycosidase digestion method was also adopted. The combined data revealed that the Fab region of anti-EGFR antibody produced by CHO cell expression system had a pattern of glycosylation differing from that of the SP2/0 cell expression system whereas the Fc region remained basically unchanged. We confirmed that anti-EGFR antibody produced by SP2/0 cell expression system had a much more diverse mixture of glycans with α-Gal and an undesired, aberrant form of sialylation N-glycolylneuraminic acid (NGNA). The α-Gal was absent in mAb produced by CHO cell expression system containing sialic acid predominantly N-acetyl neuraminic acid (NANA) which is the desired, normal human-type sialylation. This study theoretically predicts that anti-EGFR antibody produced by CHO cell expression system may show better clinical tolerance, and very low potential for active hypersensitivity reactions, CHO cell lines can be the preferred expression system for producing anti-EGFR biobetter.

We compared the similarity of Omalizumab (Xolair; a humanized anti-immunoglobulin E monoclonal antibody) and it's biosimilar CMAB007. An in depth characterization of a candidate biosimilar was carried out using a systematic approach, the approach provides a set of routine tools that combine accurate intact mass measurement, peptide mapping, and released glycan profiling. CMAB007 and Omalizumab had the same primary structure and exhibited almost the same content of C-terminal lysine variants. The types of detected free oligosaccharides were very similar, such as sialylation, fucosylation and high mannose types. CMAB007 could be considered as a highly similar molecular to Omalizumab and expected to be the first humanized anti-immunoglobulin E monoclonal antibody drug in China.
Biosimilar Pharmaceuticals ; chemistry ; Chromatography, Liquid ; Glycosylation ; Humans ; Mannose ; chemistry ; Mass Spectrometry ; Omalizumab ; chemistry ; Peptide Mapping ; Polysaccharides ; chemistry