Protocols for the analytical characterization of therapeutic monoclonal antibodies. I - Non-denaturing chromatographic techniques.

Size-, charge- and hydrophobicity-related variants of a biopharmaceutical product have to be deeply characterized for batch consistency and for the assessment of immunogenicity and safety effects. Size exclusion chromatography (SEC) and ion exchange chromatography (IEX) are considered as the gold standard for the analysis of high molecular weight species (HMWS) and charge-related variants, respectively. Hydrophobic interaction chromatography (HIC) has drawn renewed attention to monitor the small drug payload distribution in the cysteine-linked antibody-drug conjugates (ADC). These three chromatographic techniques, namely SEC, HIC and IEX, are historical, non-denaturing and robust approaches widely used for the characterization of biopharmaceutical proteins. Despite the broad spectrum of monoclonal antibodies (mAbs) structures, isoelectric points (pIs) and hydrophobicities, generic protocols can be applied to separate their size-, charge- and hydrophobicity-related variants, using the last generation of chromatographic columns and appropriate mobile phase conditions. Straightforward protocols are described in this manuscript with representative chromatograms of ten distinct Food and Drug Administration (FDA) and European Medicines Agency (EMA) approved therapeutic mAb products to illustrate the performance of the SEC, IEX and HIC methods.