The goal of protein formulation development is to identify optimal conditions for long-term storage. Certain commercial conditions (e.g., high protein concentration or turbid adjuvanted samples) impart additional challenges to biophysical characterization. Formulation screening studies for such conditions are usually performed using a simplified format in which the target protein is studied at a low concentration in a clear solution. The failure of study conditions to model the actual formulation environment may cause a loss of ability to identify the optimal condition for target proteins in their final commercial formulations. In this study, we utilized a steady-state/lifetime fluorescence-based, high-throughput platform to develop a general workflow for direct formulation optimization under analytically challenging but commercially relevant conditions. A high-concentration monoclonal antibody (mAb) and an Alhydrogel-adjuvanted antigen were investigated. A large discrepancy in screening results was observed for both proteins under these two different conditions (simplified and commercially relevant). This study demonstrates the feasibility of using a steady-state/lifetime fluorescence plate reader for direct optimization of challenging formulation conditions and highlights the importance of performing formulation optimization under commercially relevant conditions.
Keywords: excipient screening; high-throughput; intrinsic fluorescence; melting temperature; protein formulation.