Isolation and characterization of therapeutic antibody charge variants using cation exchange displacement chromatography.

In this report, we have demonstrated the isolation and enrichment of charge variants of a monoclonal antibody IgG1 using cation exchange displacement chromatography. We successfully achieved the separation of acidic, main and basic charge variants with high recovery (>70%) and purity (>90%) by using a commercially available stationary phase in conjunction with a commercially available displacer. In addition, we have isolated and enriched a trace methionine-oxidized variant of the monoclonal antibody allowing a secondary means of identification of this variant while providing sufficient enrichment for further analysis, stability tests and potency determination. Further characterization of the displacement trains by SEC indicate the possibility of enrichment of high and low molecular weight species. Glycan analysis of the displacement fractions indicates minimal variation in glycan distribution patterns among a wide spectrum of charge variants. These results provide a case study demonstrating the utility of cation exchange displacement chromatography as a viable approach to isolate and enrich antibody charge variants for enhanced molecular characterization.