Evaluation of high-capacity cation exchange chromatography for direct capture of monoclonal antibodies from high-titer cell culture processes

Advances in molecular biology and cell culture technology have led to monoclonal antibody titers in excess of 10g/L. Such an increase can pose concern to traditional antibody purification processes due to limitations in column hardware and binding capacity of Protein A resins. Recent development of high capacity cation exchangers can make cation exchange chromatography (CEX) a promising and economic alternative to Protein A capture. This work investigates the feasibility of using CEX for direct capture of monoclonal antibodies from high titer cell culture fluids. Two resin candidates were selected from seven newer generation cation exchangers for their higher binding capacity and selectivity. Two monoclonal antibodies with widely differing pI values were used to evaluate the capability of CEX as a platform capture step. Screening of loading pH and conductivity showed both resins to be capable of directly capturing both antibodies from undiluted cell culture fluid. At appropriate acidic pH range, product loading of over 65g/L resin was achieved for both antibodies. A systematic design of experiment (DOE) approach was used to optimize the elution conditions for the CEX step. Elution pH showed the most significant impact on clearance of host cell proteins (HCPs). Under optimal conditions, HCP reduction factors in the range of 9-44 were achieved on the CEX step based on the pI of the antibody. Apart from comparing CEX directly to Protein A as the capture method, material from either modality was also processed through the subsequent polishing steps to compare product quality at the drug substance level. Process performance and product quality was found to be acceptable using the non-affinity based process scheme. The results shown here present a cheaper and higher capacity generic capture method for high-titer antibody processes. Biotechnol. Bioeng. 2014;111: 1354-1364. (c) 2014 Wiley Periodicals, Inc.