Weak partitioning chromatography (WPC) is an isocratic chromatographic protein separation method performed under mobile phase conditions where a significant amount of the product protein binds to the resin, well in excess of typical flowthrough operations. The more stringent load and wash conditions lead to improved removal of more tightly binding impurities, although at the cost of a reduction in step yield. The step yield can be restored by extending the column load and incorporating a short wash at the end of the load stage. The use of WPC with anion exchange resins enables a two-column cGMP purification platform to be used for many different mAbs. The operating window for WPC can be easily established using high throughput batch-binding screens. Under conditions that favor very strong product binding, competitive effects from product binding can give rise to a reduction in column loading capacity. Robust performance of WPC anion exchange chromatography has been demonstrated in multiple cGMP mAb purification processes. Excellent clearance of host cell proteins, leached Protein A, DNA, high molecular weight species, and model virus has been achieved.

Ion-exchange (IEX) chromatography steps are widely applied in protein purification processes because of their high capacity, selectivity, robust operation, and well-understood principles. Optimization of IEX steps typically involves resin screening and selection of the pH and counterion concentrations of the load, wash, and elution steps. Time and material constraints associated with operating laboratory columns often preclude evaluating more than 20-50 conditions during early stages of process development. To overcome this limitation, a high-throughput screening (HTS) system employing a robotic liquid handling system and 96-well filterplates was used to evaluate various operating conditions for IEX steps for monoclonal antibody (mAb) purification. A screening study for an adsorptive cation-exchange step evaluated eight different resins. Sodium chloride concentrations defining the operating boundaries of product binding and elution were established at four different pH levels for each resin. Adsorption isotherms were measured for 24 different pH and salt combinations for a single resin. An anion-exchange flowthrough step was then examined, generating data on mAb adsorption for 48 different combinations of pH and counterion concentration for three different resins. The mAb partition coefficients were calculated and used to estimate the characteristic charge of the resin-protein interaction. Host cell protein and residual Protein A impurity levels were also measured, providing information on selectivity within this operating window. The HTS system shows promise for accelerating process development of IEX steps, enabling rapid acquisition of large datasets addressing the performance of the chromatography step under many different operating conditions.

In the biopharmaceutical industry, well‐executed process development and characterization studies ensure robust manufacturing processes. In conventional chromatography, these studies are carried out in series with ≥10 mL bed volumes, thus requiring large quantities of feed material and operator oversight. For that reason, the screening of large process spaces becomes very expensive and has the potential to negatively impact other projects in a company's portfolio competing for similar resources. In this study, we evaluated the ability of the three high‐throughput process development formats 96‐well filter plates, pipette tips, and mini columns to reduce resources in a late‐phase process characterization Protein A capture step. The study used a Protein A capture step with a single experimental design, mAb feed material, and analytical package. The evaluation was based on how identical batch and dynamic process parameters impacted the quality and process performance attributes of monomer purity, host cell protein levels, and yield. All formats were able to provide similar models for product yield and monomer purity. Except for practical limitations of PreDictor plates, all formats could identify significant factors for host cell protein levels. RoboColumn units enabled dynamic factor evaluation and the results were the most comparable to conventional chromatography.