278675 Prediction and Accelerated Test of Antibody Aggregation

Tuesday, October 30, 2012: 1:24 PM
Washington (Westin )
Jonathan Rubin1, Lars Linden2, Wayne M. Coco3, Andreas S. Bommarius1 and Sven H. Behrens1, (1)Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, (2)Bayer Pharmaceuticals, Wuppertal, Germany, (3)Bayer Healthcare AG, Cologne, Germany

Physical stability is critical for any therapeutic protein’s efficacy and economic viability. No reliable theory exists to predict stability de novo, and modeling aggregation is challenging as this phenomenon involves unfolding and rearrangement of non-covalent bonds inter- and intra-molecularly in a complex sequence of poorly understood events. Despite this complexity, the simple observation of protein concentration-dependent diffusivity in stable, low ionic-strength solutions can provide valuable information about a protein’s propensity to aggregate at much higher salt concentrations and over longer time scales. We recently verified this notion using two model proteins, and other studies have shown that this strategy may be applicable to antibodies as well.  In this paper, we expand our previous study to a pharmaceutically relevant hIgG1 antibody and discuss the merits and limitations of stability assessments based on the diffusional virial coefficient kD.  We find this interaction parameter to be a good predictor of relative protein stability in solutions of different chaotropic salts, and a telling heuristic for the effect of kosmotropes. Both temperature and glycosylation are seen to have a strong influence on kD, and we examine how these factors affect stability assessments. Further, we monitor protein unfolding using a fluorescence assay to assist in interpreting the observed rates of salt-induced aggregation.

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