(618i) Optimization of Ultrafiltration and Diafiltration Process for a Shear Sensitive and Aggregation Prone Monoclonal Antibody

A traditional process for monoclonal antibody (mAb) purification ends with an ultrafiltration and diafiltration step. The purpose of Ultrafiltration (UF) is to concentrate and buffer exchange the monoclonal antibody into final formulation. In this case study, the final purification chromatography before the UF step is the hydrophobic interaction chromatography (HIC). The HIC was a prior polishing step to remove process impurities and aggregates, and the target mAb was eluted into a high concentration of sodium sulfate buffer. The HIC chromatography separated impurities from mAb based on hydrophobic interactions of the resin ligand and non-polar regions of the protein. The biochemical properties coupled with the high sodium sulfate concentration in the HIC process conditions resulted in low step yield and increase of aggregates over time under stress conditions. It was expected that during the initial concentration phase of the UF step, the presence of high concentrated sodium sulfate might lead to a higher surface hydrophobicity increasing antibody self-association and binding to the UF membrane. Multiple process parameters were investigated to mitigate the issue: sodium sulfate concentration for UF feed, membrane loading capacities, protein concentration of feed during at diafiltration, and impact of shear force on aggregate formation. Rheometer studies using feed streams with varying sodium sulfate concentration and impurity levels suggested that protein aggregation increased in the presence of high sodium sulfate concentration. Additional studies including investigation of loading capacities and diafiltration feed concentrations were executed to define the ultrafiltration parameters for scale-up. The developed UF process was incorporated into a successful pilot and GMP manufacturing scale to support clinical demands.