title: Method development for the separation of monoclonal antibody charge variants in cation exchange chromatography, Part I: salt gradient approach.
abstract: Ion exchange chromatography (IEX) is a historical technique widely used for the detailed characterization of therapeutic proteins and can be considered as a reference and powerful technique for the qualitative and quantitative evaluation of charge variants. When applying salt gradient IEX approach for monoclonal antibodies (mAbs) characterization, this approach is described as time-consuming to develop and product-specific. The goal of this study was to tackle these two bottle-necks. By modeling the retention of several commercial mAbs and their variants in IEX, we proved that the mobile phase temperature was not relevant for tuning selectivity, while optimal salt gradient program can be easily found based on only two initial gradients of different slopes. Last but not least, the dependence of retention vs. pH being polynomial, three initial runs at different pH were required to optimize mobile phase pH. Finally, only 9h of initial experiments were necessary to simultaneously optimize salt gradient profile and pH in IEX. The data can then be treated with commercial modeling software to find out the optimal conditions to be used, and accuracy of retention times prediction was excellent (less than 1% variation between predicted and experimental values). Second, we also proved that generic IEX conditions can be applied for the characterization of mAbs possessing a wide range of pI, from 6.7 to 9.1. For this purpose, a strong cation exchange column has to be employed at a pH below 6 and using a proportion of NaCl up to 0.2M. Under these conditions, all the mAbs were properly eluted from the column. Therefore, salt gradient CEX can be considered as a generic multi-product approach.
authors.affiliation: School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Boulevard d'Yvoy 20, 1211 Geneva 4, Switzerland. Electronic address: szabolcs.fekete@unige.ch.
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Fekete
authors.affiliation: Center of Immunology Pierre Fabre, 5 Avenue Napoléon III, BP 60497, 74160 Saint-Julien-en-Genevois, France(1).
authors.forename: Alain
authors.initials: A
authors.lastname: Beck
authors.affiliation: Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Szt. Gellért tér 4., 1111 Budapest, Hungary.
authors.forename: Jenő
authors.initials: J
authors.lastname: Fekete
authors.affiliation: School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Boulevard d'Yvoy 20, 1211 Geneva 4, Switzerland.
authors.forename: Davy
authors.initials: D
authors.lastname: Guillarme
mesh_terms: D000911:Antibodies, Monoclonal / Q000032:analysis* / Q000737:chemistry*; D002852:Chromatography, Ion Exchange; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D012965:Sodium Chloride / Q000737:chemistry*; D013696:Temperature
chemical_list: D000911:Antibodies, Monoclonal; D012965:Sodium Chloride
keywords: Cetuximab; Ion exchange; Method development; Monoclonal antibody; Salt gradient