Separation of populations of antibody variants by fine tuning of hydrophobic-interaction chromatography operating conditions.

The following report describes the use of hydrophobic-interaction chromatography (HIC) to separate and characterize populations of monoclonal antibodies resulting from variable N- and C-terminal processing, stressed-induced covalent modifications and conformationally altered populations present in the drug product. We investigated the use of HIC to characterize heterogeneity in the intact molecule and the Fab and Fc sub-domains resulting from papain cleavage. We found that certain classes of covalent modifications to antibodies are highly amenable to HIC separation. Specific covalent modifications occurring on antibodies could be separated into pure fractions which contained unmodified, singly modified (on 1 heavy or light chain) and doubly modified (on both heavy or light chains) molecules. This report demonstrates the utility of HIC for assessing the heterogeneity, stability and, in some cases, potency of monoclonal antibodies.