Clearance of aggregates during protein purification is increasingly paramount as protein aggregates represent one of the major impurities in biopharmaceutical products. Aggregates, especially dimer species, represent a significant challenge for purification processing since aggregate separation coupled with high purity protein recovery can be difficult to accomplish. Biochemical characterization of the aggregate species from the hydrophobic interaction and cation exchange chromatography elution peaks revealed two different charged populations, i.e. heterogeneous charged aggregates, which led to further challenges for chromatographic removal. This paper compares multimodal versus conventional cation exchange or hydrophobic chromatography methodologies to remove heterogeneous aggregates. A full, mixed level factorial design of experiment strategy together with high throughput experimentation was employed to rapidly evaluate chromatographic parameters such as pH, conductivity, and loading. A variety of operating conditions were identified for the multimodal chromatography step, which lead to effective removal of two different charged populations of aggregate species. This multimodal chromatography step was incorporated into a monoclonal antibody purification process and successfully implemented at commercial manufacturing scale.

Application of scale-down high-throughput screening has become integral for process development of antibody therapeutic products. In this work, methods are described for using high-throughput techniques to develop a multicolumn chromatography purification protocol for a small domain antibody with very limited material (<200 mg). Screenings utilized resin slurry plates to explore and narrow potential operating space, and miniature columns were used to either confirm operating spaces or further explore impurity separations. Lab scale column confirmations were performed when appropriate. Affinity capture chromatography as well as ion exchange and multimodal polishing chromatography steps were explored. Feedstreams were pooled and recycled to preserve material for the different chromatography steps. Precise high-throughput analytical assays were developed to fully characterize the domain antibody to a similar extent as a typical commercial therapeutic protein program. Optimized two-column and three-column processes provided overall chromatography yields of 66 and 58%, respectively, and were able to meet typical early phase requirements for removal of impurities such as aggregates, host cell protein, endotoxin, and other product-related impurities. This study provides a comprehensive example of how a thorough biologics downstream process can be developed with a minimum of material.