(620n) Characterization and Reduction of Host Cell Protein Contaminants Via Mass Spec, Purification Optimization and Cellular Engineering

Host cell proteins (HCP) generated during cell culture processes to produce monoclonal antibody (mAb) therapeutics continue to be a contaminant in purified drug substance. Interactions between the HCPs and mAb products or purification matrices have made it difficult to remove these contaminants and result in significant downstream processing and ultimately increased production costs. Because we apply a platform cell culture process to our antibody programs, this provides a unique opportunity for characterization of the specific HCPs generated by our hosts and potential for engineering of the host cell line to reduce or eliminate expression of these proteins. To this end, we propose using mass spectroscopy to characterize the HCPs produced by our Chinese hamster ovary (CHO) host line expressing different platform antibody products. By comparing these products to material made using a null CHO host we will gain fundamental understanding of how different antibody expression affects the HCP profile. In addition, we will identify common HCPs which are non-essential to cellular function as candidates for cellular engineering, and perform proof of concept experiments to demonstrate reduction or removal of these HCPs in the culture supernatant. In parallel, studies optimizing purification conditions will be conducted to determine whether the process can be improved to reduce the HCPs without modification to the host cell line. We hope that this collaborative approach will not only strengthen our understanding of the cell’s expression of HCP contaminants but also provide novel methods to remove some of the HCPs during downstream purification of monoclonal antibody products.