In 2018, twelve antibody therapeutics were awarded first approval in either the European Union (EU) or United States (US) and it is forecasted that another twelve may enter regulatory review in 2019.1 mAbs are complicated, large (150 kDa) multi-subunit proteins which undergo post-translational modifications to generate heterogenous products. The activity, efficacy and immunogenicity of mAbs are influenced by primary structure, post translational modifications and higher order structure and control of these should be demonstrated during development and manufacture. This discussion will concentrate on the analytics required for structural characterisation of a mAb in line with regulatory guidances such as the ICH Q6B. During such analysis, data on product related impurities also assist in identification of potential deleterious variants and allow assessment of product heterogeneity. 

Mab Services

• Intact molecular weight (MW) and MW distribution (mass spectrometry, SEC-MALS) 

• Amino acid sequence and composition (peptide mapping, mass spectrometry, amino acid analysis) 

• Glycan profiling (HILIC-FLR-MS) 

• Extinction coefficient determination and validation

• Electrophoretic and isoform patterns (cIEF, gel IEF, SDS PAGE, Western Blot, CZE)

• Liquid chromatographic patterns (RP-HPLC, Ion Exchange HPLC, SEC)

• Spectroscopic profile (CD, NMR, FTIR, Fluorescence) for secondary and higher order structure 

• Disulphide bridge mapping (Mass spectrometry)

• Terminal amino acid sequencing including K clipping, proline amidation, pyroglutamic acid. (mass spectrometry, CE)

• Evaluation of PTMs including oxidation and deamidation (Mass spectrometry, cIEF) 

• Cell based bioassays for potency

• Biologic potency assessment

• Product related impurity assessment (RP-HPLC, Ion exchange HPLC, Mass spectrometry) 

• Aggregation studies (SEC, DLS, western blot) 

• Forced degradation studies

• Quantification of host cell proteins (HCP) - total or individual HCPs and residual DNA

• Physicochemical properties (includes colour, clarity / opalescence, pH, particulates, turbidity, extractable volume, moisture, osmolality) 

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