Effective protocol for the investigation of physicochemical and conformational stability and aggregation kinetics measurements of therapeutic IgG2 monoclonal antibody.

Characterisation of monoclonal antibodies (mAbs) represents an ongoing challenge due to their diverse 3-dimensional structures that can affect their stability, immunogenicity and/or toxicity. Although circular dichroism (CD) spectroscopy provides rapid determinations of protein secondary structure in solutions, there is a pressing need for an improvement in current practices in applying the technique for batch QC. There is a lack of experimental evidence in the literature which is concerned with improving the current practices. This work is based on an effective protocol for the study of IgG2a stability in solution using the simultaneous measurements of absorbance, turbidity and CD. A novel approach has been developed for the study of the effects of pH and additives with minimum protein shock that may cause premature aggregation and deceptive results. A computer programme has been designed for the rapid and simultaneous analysis of aggregation during UV and CD measurements, also, highlighting instrumental variations. Temperature stability determination, elucidation of unfolding pathways and aggregation kinetics were estimated with accuracy. This experimental approach provides important information about mAbs physicochemical and conformational stability, helps distinguish between unfolded, refolded, aggregated, and flocculated states and is an excellent tool in the development of therapeutic antibodies.