Modeling on-column reduction of trisulfide bonds in monoclonal antibodies during protein A chromatography

- Trisulfide formation in monoclonal antibodies is a source of product heterogeneity that needs to be controlled for consistent product quality.
- Incorporating cysteine wash during Protein A chromatography can help to lower trisulfides to acceptable levels.
- A simple mathematical predictive model can really aid our fundamental understanding and be a valuable tool to guide future optimization of this wash step.

Trisulfides can be a common post-translational modification in many recombinant monoclonal antibodies. These are a source of product heterogeneity that add to the complexity of product characterization and hence, need to be reduced for consistent product quality. Trisulfide bonds can be converted to the regular disulfide bonds by incorporating a novel cysteine wash step during Protein A affinity chromatography. An empirical model is developed for this on-column reduction reaction to compare the reaction rates as a function of typical operating parameters such as temperature, cysteine concentration, reaction time and starting level of trisulfides. The model presented here is anticipated to assist in the development of optimal wash conditions for the Protein A step to effectively reduce trisulfides to desired levels.