(523e) Enhancing Aggregate Reduction Using Anion Exchange Hybrid Filter in an Immunocytokine Diabody Fusion Protein Purification Process

An immunocytokine diabody fusion protein presented severe aggregation issue. To reduce aggregates in the purification process, a variety of depth filters were evaluated for harvest clarification and post-Protein A intermediate filtration. A fully synthetic quaternary amine functionalized anion exchange (AEX) hybrid nonwoven filter (Emphaze™ AEX Hybrid Purifier) demonstrated significant aggregate reduction in both harvest clarification and post-Protein A intermediate filtrations. Pre-filters were identified to improve Emphaze filter throughput and further enhance aggregate reduction during the harvest clarification. The effect of operating pH and feed stream aggregate level were evaluated for Emphaze filter for the post-Protein A intermediate filtration. Furthermore, the aggregate binding capacity of the Emphaze filter was assessed to optimize the aggregate removal. Finally, the aggregate binding mechanism was elucidated as a dominating electrostatic adsorption and was compared against another fully synthetic depth filter. The implementation of Emphaze filter resulted in greater than 20% aggregates reduction, which significantly reduced the impurity clearance workload on chromatography steps and simplified the process while achieving a desirable product quality for the diabody fusion protein.

Keywords: Immunocytokine, Diabody, Fusion Protein, Clarification, Depth Filtration, Aggregates, Host Cell Protein, Anion Exchange.