Biopharmaceutical development at PLS begins with a stage-appropriate approach to understand the key biophysical and chemical properties of the biologic drug substance. In general, early-stage development can be supported with a limited number of analytical methods, for example SEC, cIEF, UV-Vis spectroscopy, CE-SDS and LC-MS. As the program advances, however, additional techniques are implemented to better characterize the drug substance, and additional chromatographic methods are developed to support formulation development. Pace develops the requisite methods de novo or installs existing methods. With complex molecules, whether they are proteins, antibodies or various conjugates, a battery of orthogonal methods typically determines all relevant properties of either the drug substance or the drug product. The higher order structure and folding properties of biologics are interrogated through an array of biophysical characterizations.
Secondary Structure
Circular dichroism is used to determine the composition of secondary structural elements in a protein. This technique is also used to determine changes in secondary structure as a function of storage conditions or environmental stressors, such as heat.
Propensity for Self-Association
The propensity of mAb molecules to self interact in solution is another important preformulation assessment that can inform clone selection or the identity of formulation excipients. Experiments conducted using DLS plate reader to determine the interaction parameter kD or the second virial coefficient (A2) by SEC-MALS or AF4-MALS can be an early stage predictor of constructs or formulations that will be susceptible to biologic aggregation.
Propensity for Unfolding and Aggregation
In addition to the tracking of chemical changes that are largely covered by the suite of analytical tools. Screening and ranking of conformational and colloidal stability is important for initial determinations of solution stability in a particular formulation or when determining a lead construct. This is accomplished by an array of biophysical tools to look at thermodynamic parameters and secondary structure changes during local unfolding, global unfolding, and aggregation and precipitation processes. Processing and storage conditions that are important for downstream developability are also worth assessing, such as the environmental destabilizers of light, agitation, freeze-thaw and shear and assessing the physicochemical changes that may occur upon exposure to various processing, storage and administration materials. Our assessments include CD thermomelt, DSF, DSC, DLS thermomelt and turbidity by UV/Fluorescence.
