Monitoring of host cell proteins (HCPs) by ELISA to show clearance during drug substance (DS) purification is an essential function of process development and quality control groups in the biopharmaceutical industry. To qualify whether an ELISA is fit for the purpose of downstream process monitoring, dilutional linearity, accuracy, precision, and LLOQ, data are collected with in-process and DS samples. A coverage assessment is performed on the antibody to demonstrate that the antibodies used in the assay are broadly reactive to the HCPs in the process to complete the qualification package. Antibody coverage assessments report the percentage of HCPs in a bioprocess that are immunoreactive, detected, and can be quantified by the ELISA.
Biopharmaceutical companies use qualification data packages as the basis for performing their ELISA assay validation. Once validated ELISA assays have been approved by regulatory groups, it can be difficult to change them and time intensive to re-validate in a cGMP environment. It is imperative to ensure a stock of validated ELISA assays from trusted suppliers can last throughout the lifetime of a program, supporting Phase I to III clinical trials and post-market product lifecycles. However, since ELISA polyclonal antibodies and kits do not have indefinite supplies, bridging studies to compare the performance of new or resupply reagents are required for continued HCP clearance monitoring. Typically, Quality Control (QC) groups will revalidate the resupply reagents and often outsource the antibody coverage assessment work.
Cygnus Technologies is transitioning the CHO HCP ELISA, 3G Kit (Item Number F550) to the resupply version (Item Number F550-1). To enable the HCP community to seamlessly transition from the original F550 kit to the F550-1 CHO HCP ELISA 3G, we performed a comparative coverage analysis study to assess reactivity of anti-CHO HCP antibodies that support F550 and F550-1 kits, respectively. The study was carried out using AAE-MS for HCP detection.