Predicting accelerated aggregation rates for monoclonal antibody formulations, and challenges for low-temperature predictions.

Nonnative aggregation is a common degradation route for therapeutic proteins. Control of aggregate levels inherently requires control and/or prediction of aggregation rates at formulation conditions and storage temperatures of practical interest. Additionally, formulation screening often involves generation of accelerated stability data at one or more temperatures. A temperature-scanning approach for measuring nonnative aggregation rates as a function of temperature is proposed and evaluated here for a monoclonal antibody across different formulation conditions. Observed rate coefficients of aggregation (kobs ) were determined from isothermal kinetic studies for a range of pH and salt conditions at several temperatures, corresponding to shelf lives spanning multiple orders of magnitude. Isothermal kobs values were efficiently and quantitatively predicted by the temperature-scanning monomer loss (TSML) approach at accelerated conditions (half lives of the order 10(-1) -10(2) h). At lower temperatures, non-Arrhenius behavior was apparent in some cases, and was semi-quantitatively described by nonlinear van't Hoff contributions to monomer unfolding free energies. Overall, the results demonstrate a novel strategy to quantitatively determine aggregation rates at time scales of industrial interest, based on kobs values from TSML, which are sample- and time-sparing as compared with traditional isothermal approaches, and illustrate challenges for shelf-life prediction with non-Arrhenius kinetics.