Improved Identification and Quantification of Host Cell Proteins (HCPs) in Biotherapeutics Using Liquid Chromatography-Mass Spectrometry

Host cell proteins (HCPs) are classified as one of the major process-related impurities in the production of recombinant therapeutic proteins. The presence of host cell proteins in the final drug product can elicit adverse patient immunogenic reaction and result in a loss of drug efficacy. Regulatory guidelines mandate the establishment of suitable analytical methods to ensure accurate determination of residual HCPs and demonstrate that contaminant levels are minimized during the bioprocess development of the therapeutic modality. Detailed analytical information on HCP composition can help to develop an efficient and robust bioprocess so the final products meet the HCP regulatory guidelines, therefore protecting patient safety. The aim of this chapter is to compare different analytical methods that are commonly used by the biopharmaceutical industry (also globally accepted by regulatory bodies) for the analysis of HCPs, review the strengths and limitations of the analytical methodologies, and then propose a rational, cost-effective strategy based on liquid chromatography-mass spectrometry (LC-MS) for HCP identification and quantitation. A range of immunospecific (e.g. enzyme-linked immunosorbent immunities assays (ELISA) and Western blot) and non-specific methods (e.g. two-dimensional difference gel electrophoresis (2D-DIGE) and LC-MS) are discussed with a primary focus on the application of LC-MS approaches for HCP analysis for bioprocessing strategies and purification development. The chapter also presents several case studies on how 2D-LC-MS methods are used to acquire the identity and measure the concentration of individual HCP in biopharmaceutical samples from bioprocess development, demonstrating the power of the technique for defining a pharmaceutical product.