title: Aggregation and chemical modification of monoclonal antibodies under upstream processing conditions.
abstract: OBJECTIVE
  To investigate antibody stability and formation of modified species under upstream processing conditions.
  
  
  METHODS
  The stability of 11 purified monoclonal human IgG1 and IgG4 antibodies, including an IgG1-based bispecific CrossMab, was compared in downscale mixing stress models. One of these molecules was further evaluated in realistic bioreactor stress models and in cell culture fermentations. Analytical techniques include size exclusion chromatography (SEC), turbidity measurements, cation exchange chromatography (cIEX), dynamic light scattering (DLS) and differential scanning calorimetry (DSC).
  
  
  RESULTS
  Sensitivity in downscale stress models varies among antibodies and results in formation of high molecular weight (HMW) aggregates. Stability is increased in cell culture medium and in bioreactors. Media components stabilizing the proteins were identified. Extensive chemical modifications were detected both in stress models as well as during production of antibodies in cell culture fermentations.
  
  
  CONCLUSIONS
  Protective compounds must be present in chemically defined fermentation media in order to stabilize antibodies against the formation of HMW aggregates. An increase in chemical modifications is detectable in bioreactor stress models and over the course of cell culture fermentations; this increase is dependent on the expression rate, pH, temperature and fermentation time. Consequently, product heterogeneity increases during upstream processing, and this compromises the product quality.
authors: Pharma Research and Early Development, Roche Diagnostics GmbH, Nonnenwald 2, 82372, Penzberg, Germany.
authors: Stefan
authors: S
authors: Dengl
authors: Marc
authors: M
authors: Wehmer
authors: Friederike
authors: F
authors: Hesse
authors: Florian
authors: F
authors: Lipsmeier
authors: Oliver
authors: O
authors: Popp
authors: Kurt
authors: K
authors: Lang
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D019149:Bioreactors; D016466:CHO Cells; D018929:Cell Culture Techniques; D006224:Cricetinae; D005285:Fermentation; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry*; D055550:Protein Stability; D013314:Stress, Mechanical; D013696:Temperature
chemical_list: D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G