ABSTRACT
Modifications like asparagine deamidation, aspartate isomerization, methionine oxidation, and lysine glycation are typical degradations for recombinant antibodies. For the identification and functional evaluation of antibody critical quality attributes (CQAs) derived from chemical modifications in the complementary-determining regions (CDRs) and the conserved regions, an approach employing specific stress conditions, elevated temperatures, pH, oxidizing agents, and forced glycation with glucose incubation, was applied. The application of the specific stress conditions combined with ion exchange chromatography, proteolytic peptide mapping, quantitative liquid chromatography mass spectrometry, and functional evaluation by surface plasmon resonance analysis was adequate to identify and functionally assess chemical modification sites in the CDRs of a recombinant IgG1. LC-Met-4, LC-Asn-30/31, LC-Asn-92, HC-Met-100c, and HC Lys-33 were identified as potential CQAs. However, none of the assessed degradation products led to a complete loss of functionality if only one light or heavy chain of the native antibody was affected.
Subject(s)
Complementarity Determining Regions/metabolism , Glycation End Products, Advanced/metabolism , Immunoglobulin G/metabolism , Peptide Mapping/methods , Recombinant Proteins/metabolism , Chromatography, Ion Exchange , Chromatography, Liquid , Hot Temperature , Humans , Hydrogen-Ion Concentration , Mass Spectrometry , Oxidative Stress , Protein Processing, Post-Translational , Proteolysis , Surface Plasmon ResonanceABSTRACT
The presence of oxidized methionine residues in therapeutic monoclonal antibodies can potentially impact drug efficacy, safety, as well as antibody half-life in vivo. Therefore, methionine oxidation of antibodies is a strong focus during pharmaceutical development and a well-known degradation pathway. The monitoring of methionine oxidation is currently routinely performed by peptide mapping/liquid chromatography-mass spectrometry techniques, which are laborious and time consuming. We have established analytical protein A chromatography as a method of choice for fast and quantitative screening of total Fc methionine oxidation during formulation and process development. The principle of this method relies on the lower binding affinity of protein A for immunoglobulin G-Fc domains containing oxidized methionines, compared with nonoxidized Fc domains. Our data reveal that highly conserved Fc methionines situated close to the binding site to protein A can serve as marker for the oxidation of other surface-exposed methionine residues. In case of poor separation of oxidized species by protein A chromatography, analytical protein G chromatography is proposed as alternative. We demonstrate that analytical protein A chromatography, and alternatively protein G chromatography, is a valuable tool for the screening of methionine oxidation in therapeutic antibodies during formulation and process development.
