Factorial screening of antibody purification processes using three chromatography steps without protein A

Protein A affinity chromatography is often employed as a capture step to meet the purity, yield, and throughput requirements for pharmaceutical antibody purification. However, a trade-off exists between step performance and price. Protein A resin removes 99.9% of feed stream impurities; however, its price is significantly greater than those of non-affinity media. With many therapeutic indications for antibodies requiring high doses and/or chronic administration, the consideration of process economics is critical. We have systematically evaluated the purification performance of cation-exchange, anion-exchange, hydroxyapatite, hydrophobic interaction, hydrophobic charge induction, and small-molecule ligand resins in each step of a three-step chromatographic purification process for a CHO-derived monoclonal antibody. Host cell proteins were removed to less-than-detectable for three processes (cation-exchange–anion-exchange–hydrophobic interaction chromatography, cation-exchange–anion-exchange–mixed cation-exchange chromatography, and cation-exchange–mixed cation-exchange–anion-exchange chromatography). The order of the process steps affected purification performance significantly.