Protein stability is critical to the success or failure of the development of a biopharmaceutical. Protein stability is an important parameter during production, manufacturing, formulation, long term storage, delivery to patient, and efficacy.

Highly stable proteins will likely have fewer issues during the manufacturing process, are more cost-effective to produce, and will have a better chance of remaining functional during formulation and storage without chemical alteration or aggregation. In the "Quality by Design" (QbD) approach for biopharmaceutical development, stability characterization is part of the assessment of the ‘developability’ or ‘drugability’ of a potential drug candidate, as well as during process development and manufacturing. Stability data is also incorporated in higher order structure (HOS) characterization and ‘fingerprinting’ used for manufacturing support, biocomparability and biosimilarity. Protein HOS characterization is also increasingly expected in regulatory submissions for new biopharmaceutical drugs and biosimilars.

Due to the complex nature of proteins, biophysical tools are important in the complete characterization of a biopharmaceutical product. There are several biophysical tools used to assess protein stability, including (but not limited to) circular dichroism (CD), dynamic and static light scattering (DLS and SLS), size exclusion chromatography-multi-angle light scattering (SEC-MALS), Fourier transform infrared spectroscopy (FTIR), analytical ultrafiltration (AUC), size exclusion chromatography (SEC), differential scanning fluorescence (DSF), intrinsic fluorescence (IF) and differential scanning calorimetry (DSC).

While all of these biophysical assays play an important role in biopharmaceutical development, characterizing thermal stability by DSC is critical. In a 2015 article about biophysical techniques for monoclonal antibody higher order structure characterization, Gokarn et al. stated: "DSC remains as an unparalleled technique to assess the thermodynamic stability of proteins in a given buffer condition"[1].

The focus of this whitepaper is on the use of DSC to characterize the thermal stability of protein biopharmaceuticals (primarily antibodies), and as a HOS characterization tool for the comparability of biopharmaceuticals (batch-tobatch comparison, effect of process changes, etc), and for the development of biosimilars.