Host Cell Protein (HCP)

Host Cell Protein (HCP) designates process-related impurities originating from the cells used to produce biologics, including residual proteins from expression hosts such as CHO cells, E. coli, or yeast. These impurities may persist through manufacturing and must be reduced to acceptable levels because they can impact product safety, immunogenicity, and stability.

The biopharmaceutical industry treats HCP control as a critical quality requirement in biologics manufacturing. Purification trains and process optimisation aim to remove HCPs effectively while maintaining product yield and integrity. Analytical testing commonly employs ELISA-based assays for total HCP quantification, alongside mass spectrometry methods identifying specific problematic proteins. Regulatory submissions include HCP clearance data and justification of acceptable limits, with ongoing monitoring ensuring batch consistency. Biosimilar developers must demonstrate comparable impurity profiles and robust HCP control strategies. As novel modalities and intensified processes emerge, HCP management remains essential for delivering safe, high-quality biologics.