Designing an optimized purification process means maximizing yield and purity, and at the same time controlling costs. So, you remove a lot of bulk impurities during the first steps, and focus on high yield steps at the end, when every gram is precious. If you’re purifying mAbs, it would also be good to remove impurities before affinity chromatography to protect the protein A column and reduce the need for cleaning in place (CIP).
All the above could all be achieved by introducing a multimodal ion exchange column immediately after the harvesting steps to remove substances such as DNA and host cell proteins. It will render the rest of the downstream process more robust and protect the protein A column from factors that impact its performance. Multimodal ion exchange chromatography is a rather uncomplicated step in flow-through mode and will not make your purification process unnecessarily cumbersome.
Moreover, adding this column early in the downstream process should also result in a higher purity of the mAbs, and potentially higher overall yields.
You can read much more about this including examples and technical details in these articles: