Different Post-load Wash Solutions Increase Host Cell Protein Removal of Toyopearl

Protein A has become a well-established platform for capturing of monoclonal antibodies and Fc-fusion proteins. Various Protein A resins have been commercialized, one with a higher dynamic binding capacity than the other. Especially the latest generation of Protein A resins was developed to bind large quantities of mAbs and Fc fusion proteins. One drawback of these resins is that host cell protein (HCP) clearance can be depending on the feedstream comparatively lower than for standard Protein A affinity resins. When aiming for a 2-step platform process, no compromises can be made with regards to HCP removal of the capturing step. The remaining impurity burden would have to be covered by just one subsequent chromatography step. Hence, development of strategies or procedures to reduce the HCP content of the Protein A elution pool are key for the development of such purification processes. Post load washing steps during Protein A chromatography may improve HCP clearance of the capturing step. However, the employed wash buffers must not affect other product related quality criteria, such as aggregate levels and mAb activity. Besides, the impact of different wash steps on the parameters determining process economics, that is product recovery, dynamic binding capacity and resin lifetime, should be evaluated. MATERIALS & METHODS