Monoclonal antibody N-glycosylation profiling using capillary electrophoresis - Mass spectrometry: Assessment and method validation.

Characterization of therapeutic proteins represents a major challenge for analytical sciences due to their heterogeneity caused by post-translational modifications (PTM). Among these PTM, glycosylation which is possibly the most prominent, require comprehensive identification because of their major influence on protein structure and effector functions of monoclonal antibodies (mAbs). As a consequence, glycosylation profiling must be deeply characterized. For this application, several analytical methods such as separation-based or MS-based methods, were evaluated. However, no CE-ESI-MS approach has been assessed and validated. Here, we illustrate how the use of CE-ESI-MS method permits the comprehensive characterization of mAbs N-glycosylation at the glycopeptide level to perform relative quantitation of N-glycan species. Validation of the CE-ESI-MS method in terms of robustness and reproducibility was demonstrated through the relative quantitation of glycosylation profiles for ten different mAbs produced in different cell lines. Glycosylation patterns obtained for each mAbs were compared to Hydrophilic Interaction Chromatography of 2-aminobenzamide labelled glycans with fluorescence detector (HILIC-FD) analysis considered as a reference method. Very similar glycoprofiling were obtained with the CE-ESI-MS and HILIC-FD demonstrating the attractiveness of CE-ESI-MS method to characterize and quantify the glycosylation heterogeneity of a wide range of therapeutic mAbs with high accuracy and precision.