Cation exchange membrane chromatography: An efficient alternative to multi-column for avoiding the impact of loading density variation on performance

Background: Resin-based cation exchange (CEX) column chromatography is widely used for charge variant separation/reduction. However, in a CEX process where a wash step is introduced to reduce weakly bound acidic charge variants, its performance is greatly affected by the loading density, resulting in poor robustness. We previously demonstrated that multi-column chromatography could resovle this problem, with the key strategy involving converting 3–4 large cycles into a greater number of small cycles. Recently, membrane chromatography has emerged as a promising alternative to column chromatography. CEX membrane, which can be operated under high flow rate, naturally supports the conversion of a large cycle into numerous small cycles. Objective: This study aimed to demonstrate that CEX membrane chromatography offers a superior option for addressing the low robustness in the chromatography’s wash step. Methods: CEX membrane chromatography was applied to reduce acidic charge variants, and its effectiveness was evaluated using capillary isoelectric focusing analysis of the purified samples. Results: Under appropriate conditions, CEX membrane chromatography consistently lowered acidic charge variants to the required level. Conclusion: Compared to the multi-column approach, CEX membrane chromatography allows for a more straightforward implementation, has higher productivity, and achieves greater cost efficiency. Therefore, it serves as a better alternative to address the low robustness issue.