During the development of protein formulations, excipients are tested mostly under accelerated stress conditions. To induce conformational changes and aggregation in a protein formulation and to study the influence of excipients on it, the protein is subjected to e. g. low pH, high temperatures, and different mechanical and chemical stresses in solution. Cation exchange chromatography is generally considered a mild protein purification technique. Recently it has been shown that it can lead to conformational changes and even aggregation of protein when bound to the surface of the stationary phase. <br/>The objective of this project is to establish an analytical screening method for the evaluation of excipients on the conformational stability and surface-induced aggregation of monoclonal antibodies. In contrast to in-solution tests, aggregation is induced by loading the monoclonal antibody on a strong cation exchange column and keep it idle for a specific time before eluting in a salt gradient. Depending on pH, ligand density, hold time, and temperature, the mAb changes into (partially) reversible aggregates. The effects of excipients on this reversible self-association can be evaluated on-column as well as after elution. The results are compared to conventional screening methods, e. g. nano-DSF.<br/>The approach is relevant not only for formulation development but also for solvent-modulated chromatography steps in the downstream processing of proteins.

Influence of excipients on surface-induced aggregation of a monoclonal antibody in cation exchange chromatography

ACS Fall 2021

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