(468c) New Multimodal Anion-Exchange Membranes for Purification of Therapeutic Proteins

Multimodal membranes bind proteins and bioprocess impurities through combinations of interaction modes that include Coulombic interactions, hydrophobic interactions, and hydrogen bonding. Because of the available modes of binding, these membranes can operate over a wider range of conditions than conventional membranes, enabling their use in chromatographic purification steps with minimal or no pretreatment of the feed.

In this study, we are evaluating the performance of Purilogics’ new multimodal anion exchange (MM-AEX) membrane in bind-and-elute and flow-through bioprocess operations. We begin by presenting performance data from dynamic binding capacity measurements for human immunoglobulin G, and salmon sperm DNA for a range of conductivities (1-30 mS/cm) and pH values (5-9). After showing that these membranes have high capacities at short residence times and from low to high conductivity, we will demonstrate their unmatched performance for aggregate removal during polishing step antibody purification. Protein aggregation is a growing problem in the manufacturing of biologics due to increasing solution titers. Antibody aggregates and other impurities often are removed in a three or four-step process involving ion-exchange and hydrophobic interaction chromatography columns after an initial Protein A capture step. We present case studies in which aggregates and host cell proteins (HCP) are removed in a simplified two-step monoclonal antibody (mAb) purification scheme. In this scheme, the mAb is isolated from supernatant using a Protein A chromatography step followed by a polishing step purification using Purilogics’ MM-AEX membranes operating in flow-through mode. Several mAbs were purified using the two-step purification strategy. Different buffer types (e.g., tris base, phosphate buffers) and buffer conductivities (1-15 mS/cm) were explored. HCP level and fractions of monomer, dimer and higher-order aggregates were compared before and after the polishing step. The results were compared with studies using two other leading commercial membrane products.