title: Selective antibody precipitation using polyelectrolytes: a novel approach to the purification of monoclonal antibodies.
abstract: We evaluated the potential for polyelectrolyte induced precipitation of antibodies to replace traditional chromatography purification. We investigated the impact of solution pH, solution ionic strength and polyelectrolyte molecular weight on the degree of precipitation using the anionic polyelectrolytes polyvinylsulfonic acid (PVS), polyacrylic acid (PAA), and polystyrenesulfonic acid (PSS). As we approached the pI of the antibody, charge neutralization of the antibody reduced the antibody-polyelectrolyte interaction, reducing antibody precipitation. At a given pH, increasing solution ionic strength prevented the ionic interaction between the polyelectrolyte and the antibody, reducing antibody precipitation. With increasing pH of precipitation, there was an increase in impurity clearance. Increasing polyelectrolyte molecular weight allowed the precipitation to be performed under conditions of higher ionic strength. PVS was selected as the preferred polyelectrolyte based on step yield following resolubilization, purification performance, as well as the nature of the precipitate. We evaluated PVS precipitation as a replacement for the initial capture step, as well as an intermediate polishing step in the purification of a humanized monoclonal antibody. PVS precipitation separated the antibody from host cell impurities such as host cell proteins (HCP) and DNA, process impurities such as leached protein A, insulin and gentamicin, as well as antibody fragments and aggregates. PVS was subsequently removed from antibody pools to < 1 microg/mg using anion exchange chromatography. PVS precipitation did not impact the biological activity of the resolubilized antibody.
authors.affiliation: Early Stage Purification, Process Research & Development, Genentech, Inc., DNA Way, South San Francisco, California 94080, USA. pmcd@gene.com
authors.forename: Paul
authors.initials: P
authors.lastname: McDonald
authors.forename: Corazon
authors.initials: C
authors.lastname: Victa
authors.forename: Jayme N
authors.initials: JN
authors.lastname: Carter-Franklin
authors.forename: Robert
authors.initials: R
authors.lastname: Fahrner
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000302:isolation & purification*; D016466:CHO Cells; D011232:Chemical Precipitation; D006224:Cricetinae; D003412:Cricetulus; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D009994:Osmolar Concentration; D011137:Polystyrenes / Q000737:chemistry / Q000378:metabolism*; D011145:Polyvinyls / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D013451:Sulfonic Acids / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000180:Acrylic Resins; D000911:Antibodies, Monoclonal; D011137:Polystyrenes; D011145:Polyvinyls; D013451:Sulfonic Acids; C008959:lyapolate; C006903:carbopol 940; C003321:polystyrene sulfonic acid