The Road Ahead—What’s Next for Host Cell Protein Analytics?

Host cell protein (HCP) analytics have come a long way over the last 25 years—from a black box–type approach that produced semiquantitative data at best, to groundbreaking mass spectrometry techniques that can identify every HCP in a drug substance (DS) sample. Adoption of advanced LC-MS–based methods for HCP antibody coverage analysis and identification of HCP in the final DS samples ensure that an HCP ELISA is appropriate for use in each drug substance process.

While LC-MS remains the most effective approach for identifying host HCPs, the presence of DS-derived peptides can limit sensitivity as compared with total quantification by HCP ELISA. Full HCP characterization requires combining quantification strategies. Data-independent acquisition (DIA)–based relative quantification provides broad, global profiling of the total HCP population, enabling assessment of overall process trends and comparison across samples. In contrast, stable isotope–labeled (SIL) peptides deliver accurate, absolute quantification for selected HCPs of concern in final DS samples. Used together, DIA relative quantification and SIL-based absolute quantification create a comprehensive HCP analysis workflow. Along with HCP ELISA, this integrated approach improves both process understanding and risk assessment for biologics development.