Recent advances in sample preparation and LC-MS technology have enabled identification of low-level host cell proteins in drug substance (DS) samples. While LC–MS remains the most effective approach for identifying HCPs, presence of DS-derived peptides can limit sensitivity as compared to total quantification by HCP ELISA. As a result, obtaining a comprehensive quantitative HCP profile requires a combination of LC-MS acquisition strategies.

In this webcast, Cygnus Technologies describes how data-independent acquisition (DIA)–based relative quantification provides broad, global coverage of the total HCP population, enabling assessment of overall process trends and comparative profiling 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. When combined with HCP ELISA, this integrated approach improves both process understanding and risk assessment for biologics development.

Key takeaways:

• Obtaining a comprehensive quantitative HCP profile requires a combination of untargeted and targeted LC-MS acquisition strategies.
• Absolute quantification with spiked-in peptides is a targeted method that yields high precision and accuracy, and is most suitable for analyses of critical problematic HCPs (e.g. Cygnus CHO 6xLipase™ assay) for process validation and lot release testing.
• Untargeted discovery methods, such as inSPECt™ DIA with label-free quantification, are not as accurate as absolute quantification, but are a crucial tool for comprehensive HCP profiling during process development.