Host cell proteins (HCPs)

Host cell proteins (HCPs) are a heterogeneous collection of proteins produced by the host cell expression system, such as Chinese Hamster Ovary (CHO) cells or E. coli, during the manufacture of recombinant biotherapeutic products (Wang et al., 2009, Biotechnology and Bioengineering). These proteins are considered process-related impurities that must be removed during downstream purification to ensure the safety and efficacy of the final drug (Vanderlaan et al., 2018, Journal of Pharmaceutical Sciences). While many HCPs are benign, certain species can be highly immunogenic or possess enzymatic activity, such as proteases, which can degrade the therapeutic protein (Bracewell et al., 2015, Biotechnology and Bioengineering). Regulatory agencies require stringent monitoring of HCP levels, typically using enzyme-linked immunosorbent assays (ELISA) to ensure they remain within acceptable safety limits (Hogwood et al., 2014, Current Opinion in Biotechnology). Because HCPs represent a diverse group of endogenous proteins rather than a specific molecule intended for therapeutic modulation, they are classified as contaminants rather than therapeutic targets. Their presence in a final formulation is a significant safety concern due to the potential for adverse immune reactions in patients.

Other names

Process-related impuritiesHost cell-derived proteinsEndogenous host proteins

Not applicable