Host cell proteins (HCPs) represent one of the most complex and challenging classes of process-related impurities in biopharmaceutical manufacturing. Their presence and levels are important product quality attributes that must be monitored and controlled to ensure product safety and quality. Managing HCPs is particularly challenging because of the complexity and diversity of HCP populations, the wide range of HCP concentrations, and the potential for individual HCPs to affect product quality, stability, and patient safety. Understanding how upstream processing influences HCP expression and release, and how downstream purification processes remove HCPs, is essential to developing effective control strategies.

Analytical methods used to detect and quantify HCPs, including enzyme-linked immunosorbent assays (ELISA) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), are technically complex and have inherent limitations in their ability to comprehensively characterize HCP populations. Continued advances in bioprocessing technologies, analytical methods, and risk-based control strategies are essential to improving HCP characterization and control throughout biopharmaceutical development and manufacturing. The BEBPA HCP conferences provide a welcoming, collaborative, and intellectually stimulating environment for scientists from industry, academia, and regulatory agencies to exchange knowledge, discuss technical challenges, share best practices, and advance the science of HCP characterization and control.