Category: Formulation and Quality
Purpose: Host cell protein (HCPs) are a significant class of process-related impurities commonly present in biologics and vaccines that are produced using living organisms. HCPs are also introduced into small molecule chemical drugs that are biosynthesized using crude enzyme catalysis. In both cases, residual HCPs need to be monitored and adequately removed in final drug substance to ensure product purity and patient safety. Although great attentions have focused on defining a universally acceptable limit for those impurities, the risks associated with residual HCPs on product quality, efficacy, and safety often need to be determined on a case by case basis. In this presentation, we aim to use some case studies to demonstrate the importance of holistic analytical characterization of HCP impurities for a knowledge-based risk control and risk mitigation during pharmaceutical process development.
Methods: Sandwich enzyme-linked immunosorbent assay (ELISA) was used as the workhorse for total residual HCP measurement; 1D and 2D SDS-PAGE with silver staining together with 2D-DIGE and 2D-Western blot were used to visualize the presence of residual HCPs and assess the HCP coverage by the antibody reagents used in ELISA; LC-MS/MS was used to identify and quantify individual HCPs present in process intermediates or drug substance of several pipeline products in development.
Results: Similar total amounts of residual HCP were detected in two different monoclonal antibody products under clinical development, mAb A and mAb B, both of which were purified by a platform two-column process. However, DS stability data showed significant degradation of PS80 in mAb A but not in mAb B at 3.5 months. An investigation on the HCP composition difference between mAb A and mAb B by LC-MS/MS identified PLBL2 as the major residual HCP in mAb A, whereas in mAb B other HCPs were detected without known lipase activities. This investigation helped process development team to assess the risk to product quality in each case and mitigated the risk in mAb A case by adding a third column. Similarly, in a biosynthesized chemical drug, residual HCP characterization by multiple orthogonal methods helped to build a holistic understanding on not only the total amount of HCPs but also the abundance level of individual HCP to facilitate a knowledge-based risk control for process development.
Conclusion: Given the limitations of each analytical tool for residual HCP detection and quantitation, a holistic phase-appropriate analytical characterization is required to build up the understanding of process clearance patterns of HCPs and the profile of residual HCPs in final drug substance. The knowledge built up through analytical characterization, together with process capability assessment, disease indication, and dosage form etc., helps to identify the risk priority and mitigate HCP related risks through further process development as necessary.
Dennis Driscoll– Kenilworth, New Jersey
David Chin– Kenilworth, New Jersey
Yuetian Chen– Kenilworth, New Jersey
Erik Hoyt– Rahway, New Jersey
Erik Guetschow– Rahway, New Jersey
Xuanwen Li– Kenilworth, New Jersey
Yan-Hui Liu– Kenilworth, New Jersey
Douglas Richardson– Kenilworth, New Jersey
Daisy Richardson– Kenilworth, New Jersey
Narayan Variankaval– Rahway, New Jersey
Joseph Smith– Rahway, New Jersey