Researchers at the Institute of Bioprocess Science and Engineering, BOKU University in Vienna, with co-authors from BASF SE, report that a cationic flocculant added at harvest can clarify monoclonal antibody (mAb) culture fluid and strip out host cell DNA and host cell proteins (HCPs) before any chromatography. The paper was published online in Biotechnology Progress on 2 November 2026. This brief draws only on the abstract, which was the only part of the paper we could open.
What was tested
The authors screened five cationic flocculants on two mAbs. They looked for clarification of the cell culture fluid, removal of host cell DNA and HCPs, and no loss of antibody yield or integrity. One polymer, called Polymer X in the abstract, performed best. It cut HCPs by 30% to 50% compared with an untreated reference.
The team then compared Polymer X with a commercially available polymer, Polymer D, on four different mAbs. The abstract reports a significantly higher and more robust HCP reduction with Polymer X. It also reports that Polymer X was better at removing selected high-risk HCPs, which the authors describe as known to negatively impact final product quality.
The reported numbers
- Turbidity: clarified fluid reached less than 25 NTU (nephelometric turbidity units, a measure of how cloudy the fluid is).
- Yield: more than 95% of the mAb was retained (the antibody yield after flocculation), in three of the four mAbs. The abstract does not give the figure for the fourth.
- Host cell DNA: reduced by over 99%.
- Total HCPs: reduced by up to 40%, with selected high-risk HCPs removed by over 90%.
The abstract does not give the polymer’s chemical identity, the dose, the culture format or the cell line. It does not report any scale beyond the lab experiments described, and it does not quantify the effect on downstream steps.
