Most clinically approved large biotherapeutics are monoclonal antibodies (mAbs), primarily belonging to immunoglobulin G subclass-1 (IgG1) and, to a lesser extent, IgG2 and IgG4. Glycosylation is the main source of post-translational heterogeneity of mAbs, impacting their drug therapeutic mechanism of action (MOA). Glycosylation is also one of the critical factors in drug product solubility, kinetics, stability and efficacy. Thus, monitoring glycan critical quality attributes (CQAs) is an essential part of any biopharmaceutical development. The binding affinity of an IgG to its cellular Fc receptor (FcR) depends on both its IgG subclass and Fc domain glycosylation pattern. Since composition of the N-glycans also correlates to the Antibody-Dependent Cellular Cytotoxicity (ADCC), the glycosylation pattern needs to be monitored for consistency in potency and efficacy. This applies for the original mAb biologics as well as biosimilars. In this chapter, we present a truly novel way to assess the variances in mAb glycoforms using FcγRIIIa-based affinity chromatography. First, a brief overview of the Fc receptor function is presented. Then, the principle of FcR-based affinity chromatography is explained including how this column’s potential to analyze a variety of mAbs according to their N-glycan content is highly selective and robust. Finally, we provide examples of the FcR column’s potential to improve analytical characterization of mAbs with practical applications such as effective cell line screening, monitoring of glycoengineering, process development and process control in manufacturing.
Part of the book: Monoclonal Antibodies