Advanced Characterization of Host Cell Protein Antibodies

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Importance of Host Cell Proteins in Biological Drugs

Host Cell Proteins represent a major group of process-related impurities in biological drugs produced using cell culture methods. While many HCPs are benign, some may interfere with drug efficacy and stability or cause adverse reactions in patients. In addition to performing dilution linearity, precision and accuracy studies for a given immunoassay, regulatory guidelines also require that manufacturers use orthogonal methods to ensure that the selected HCP ELISA method is fit for its intended use.

Antibody Affinity Extraction: An Advanced Orthogonal Method

Antibody Affinity Extraction (AAE) is an advanced orthogonal method used by Cygnus technologies to assess polyclonal antibody coverage for an array of HCPs that are present in a biomanufacturing process and for downstream-process-specific HCPs that could be purified alongside drug substances. This method overcomes analytical deficiencies commonly observed with two-dimensional western blotting and two-dimensional differential in-blot electrophoresis (2D DIBE) methods, which are still used by some manufacturers to assess antibody coverage to total HCP content. Unlike these electrophoresis-based methods, AAE more closely mimics the biophysical environment for the interaction between the HCP antibodies and antigens, making this assay superior in terms of predictive value.

Enrichment and Assessment of Immunoreactive HCPs

In this article, we describe how AAE enriches for immunoreactive HCPs present in your processed material, and how this method can be performed in concert with either 2D-PAGE/Silver Stain or LC-MS (AAE-MS) to provide accurate coverage assessments. Importantly, the AAE-MS method is currently the only approach that can reliably assess HCP antibody coverage when the only available sample is a product (drug substance) containing harvest material and not clarified culture fluid derived from a null cell line. Moreover, AAE-MS allows manufacturers to uncover information about which HCPs may be present in their bioprocess, providing important insights for future process improvements.

Impact on Drug Efficacy and Stability

Ultimately, AAE combined with MS provides important information impacting drug efficacy and stability, helping to minimize risk and instill confidence that the chosen HCP assay enables biomanufacturers to reduce HCPs to safe levels.