CUSTOMIZED QUANTIFICATION OF HOST CELL PROTEIN WITH BIO-LAYER INTERFEROMETRY

Abstract: Host cell protein (HCP) is quantified in the purification steps of biopharmaceutical production and is part of ensuring the purity of the final drug product. The gold standard method for HCP quantification is enzyme-linked immunosorbent assay (ELISA), but a new approach is proposed here with fully customized bio-layer interferometry assays for yeast and chinese hamster ovary (CHO) cells. The new method has been developed by proceeding from a kit assay, but exchanging and optimizing each step of the assay to ensure a fully customized assay with the maximum binding rates possible to maximize the sensitivity. Originally, 3,3'-diaminobenzidine (DAB) was used as a signal enhancer, but exchanging it to the less hazardous substrate 3-amino-9-ethylcarbazole (AEC) gave higher assay signals and better sensitivity. The developed yeast HCP quantification assay showed the ability to quantify HCP levels in samples of different concentrations. The estimated precision and lower limit of quantification (LLOQ) were of promising values, comparable to the analytical parameters of the currently used ELISA. The bio-layer interferometry (BLI) approach has the ability to reduce assay time from ELISA's usual 2 days down to 2 hours and can be almost fully automized together with a liquid handler. For pharmaceutical development, a faster HCP quantification could result in a faster feedback-loop allowing earlier adjustments to the purification process, and could be a great advantage for the aggressive deadlines that the biopharmaceutical discovery space experience.