Effect of polyol sugars on the stabilization of monoclonal antibodies

- Sugars and polyols reduce mAb aggregation propensity by increasing the mAb conformational stability.
- The stabilization is interpreted from a kinetic perspective as an increase in the energy barrier of protein unfolding.
- An alternative thermodynamic view involving a shift of the native state ensemble towards a compact structure is proposed.
- The stabilization effect increases as a function of polyol size until a plateau is reached at large polyol sizes.
- The mAb stabilization depends both on the volume fraction filled by the polyol molecules and on the polyol chemistry.

We investigate the impact of sugars and polyols on the heat-induced aggregation of a model monoclonal antibody whose monomer depletion is rate-limited by protein unfolding. We follow the kinetics of monomer consumption by size exclusion chromatography, and we interpret the results in the frame of two mechanistic schemes describing the enhanced protein stability in the presence of polyols. It is found that the stabilization effect increases with increasing polyol concentration with a comparable trend for all of the tested polyols. However, the stabilization effect at a given polyol concentration is polyol specific. In particular, the stabilization effect increases as a function of polyol size until a plateau is reached above a critical polyol size corresponding to six carbon atoms. Our results show that the stabilization by polyols does not depend solely on the volume fraction filled by the polyol molecules, but is also affected by the polyol chemistry.