Flocculation using selected cationic polymers reduces high‐risk host cell proteins in monoclonal antibody processes already during primary recovery

Highly intensified monoclonal antibody (mAb) production needs next-generation purification technologies for process streamlining. Cationic flocculants aid in clarification and can reduce DNA and host cell proteins (HCPs) decreasing the burden on purification. Using two different mAbs, we screened five different cationic flocculants for their potential to clarify cell culture fluid, while simultaneously removing host cell DNA and HCPs without affecting antibody yield and integrity. We identified Polymer X as the best performer, excelling in HCP reduction with 30%-50% reduction compared to an un-treated reference. Comparison to a commercially available polymer (Polymer D), showed a significantly higher and more robust reduction of HCPs for four different mAbs. Additionally, we investigated the reduction of high-risk HCPs, that are known to negatively impact final product quality or patient safety. We demonstrated that Polymer X excels in reduction of those compared to flocculation with Polymer D. Polymer X could be used to successfully (1) aid cell culture clarification, with achieved turbidities of less than 25 NTU, (2) maintain high mAb titers, with over 95% yield (in three out of four mAbs), (3) reduce host cell DNA by over 99% and (4) reduce total HCPs by up to 40%, including selected high-risk HCPs to be removed by over 90%. In a typical mAb purification scheme, an anion exchange chromatography is used to get rid of DNA and residual HCPs. The robust removal of HCPs and DNA shown by Polymer X might support streamlining of the purification.