title: Breaking the aggregation of the monoclonal antibody bevacizumab (avastin®) by dexamethasone phosphate: insights from molecular modelling and asymmetrical flow field-flow fractionation.
abstract: OBJECTIVE
  To investigate the mechanism behind the aggregation breaking properties of dexamethasone phosphate and related corticosteroids on the IgG1 antibody bevacizumab (Avastin®).
  
  
  METHODS
  An in silico 3D dimer model is developed to identify the bevacizumab-bevacizumab interface, and different corticosteroids are docked onto the model to distinguish preferred binding sites. In silico predictions are validated by in vitro stability studies, where the antibody is stressed in presence or absence of each corticosteroid and formed aggregates are quantified by asymmetrical flow field-flow fractionation.
  
  
  RESULTS
  The dimer model features one close crystal contact area: Lys445 on the Fc region interacts with one Fab arm of the second bevacizumab. Docking reveals an interaction between the phosphate group of dexamethasone phosphate and Lys445, while the rest of the molecule is hindering dimer formation. Predictions are confirmed in vitro, demonstrating that dexamethasone phosphate and betamethasone phosphate partly prevent antibody aggregation, whereas triamcinolone acetonide phosphate does not.
  
  
  CONCLUSIONS
  Results suggest that bevacizumab monomers follow a specific mechanism to form dimers in which a protein-protein interaction hotspot can be distinguished. The dimer formation can be hindered by corticosteroids in a specific way. This approach allows a simple way to stabilize IgG1 antibodies.
authors: School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland.
authors: Marieke
authors: M
authors: Veurink
authors: Yvonne
authors: Y
authors: Westermaier
authors: Robert
authors: R
authors: Gurny
authors: Leonardo
authors: L
authors: Scapozza
mesh_terms: D000893:Anti-Inflammatory Agents / Q000378:metabolism*; D061067:Antibodies, Monoclonal, Humanized / Q000737:chemistry / Q000378:metabolism*; D000068258:Bevacizumab; D003907:Dexamethasone / Q000031:analogs & derivatives* / Q000378:metabolism; D031521:Fractionation, Field Flow; D006801:Humans; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D055503:Protein Multimerization / Q000187:drug effects; D013314:Stress, Mechanical; D013696:Temperature
chemical_list: D000893:Anti-Inflammatory Agents; D061067:Antibodies, Monoclonal, Humanized; C004180:dexamethasone 21-phosphate; D000068258:Bevacizumab; D003907:Dexamethasone