An application of Nano Differential Scanning Fluorimetry for Higher Order Structure assessment between mAb originator and biosimilars: Trastuzumab and Rituximab as case studies

Differential scanning fluorimetry (DSF) or thermal shift has emerged in recent years as a high-throughput screening method in biotherapeutic formulation studies. The present article reports on a fast-track assessment platform for rapid investigation of therapeutic proteins such as monoclonal antibodies (mAb) with minimal sample concentration, volume, and preparation. The proposed nanoDSF platform has been demonstrated for rapid assessment of two commercial IgG 1 drug products (DP), trastuzumab and rituximab, and their biosimilars with respect to their conformational and colloidal stability. Domain specific differences for each of the IgGs have been elucidated with respect to onset of domain unfolding (T-onset) and melting temperatures. These thermal unfolding and transition midpoint (T-m) measurements are based on the intrinsic aromatic amino acid residue fluorescence of proteins. Moreover, to understand the possibility of nanoDSF as a predictive tool, data from nanoDSF has been correlated with accelerated stability studies. Melting temperatures across brands were found to be highly comparable to the rate of heating, thereby exhibiting a significant domain specific effect on melting temperatures for both trastuzumab and rituximab. Conservation of higher order structure (HOS) through reversible unfolding was also examined and both the mAbs were found to regain tertiary structure up till the first transition midpoint. No clear correlation was found between formation of higher molecular weight species (HMWS) and unfolding parameters (T-onset and T-agg) for accelerated stability studies. Finally, a discussion on the need for fast predictive assessment of conformation and colloidal stability as well as a comparison of advantages and limitations of the technique with routine/classical tools such as circular dichroism spectrophotometry and differential scanning calorimetry has been presented. (C) 2020 Elsevier B.V. All rights reserved.