Host cell protein monitoring during downstream processing using micro-pillar array columns combined with mass spectrometry

Protein biopharmaceuticals have substantially reshaped the pharmaceutical market and today over 350 products have been approved for human use in the United States and the European Union. Protein biopharmaceuticals are commonly produced recombinantly in mammalian, yeast, or bacterial expression systems. Next to the therapeutic protein, these cells produce endogenous host cell proteins (HCPs) that can contaminate the biopharmaceutical product despite multiple purification steps in a process. Since these process‑related impurities can affect product safety and efficacy, they need to be closely monitored. Enzyme-linked immunosorbent assays (ELISA) are recognized as the gold standard for measuring HCPs because of their high sensitivity and high throughput. Mass spectrometry (MS), however, is gaining acceptance as an alternative and complementary technology for HCP characterization. This article reports on the use of micro-pillar array columns combined with MS for the characterization and in-depth monitoring of HCPs during downstream processing.