PT - JOURNAL ARTICLE AU - Xuanwen Li AU - Yan An AU - Jing Liao AU - Li Xiao AU - Michael Swanson AU - Kirby Martinez-Fonts AU - Jorge Alexander Pavon AU - Edward C. Sherer AU - Vibha Jawa AU - Xinliu Gao AU - Simon Letarte AU - Douglas D. Richardson TI - Identification and Characterization of a Residual Host Cell Protein Hexosaminidase B Associated with N-glycan Degradation During the Stability Study of a Therapeutic Recombinant Monoclonal Antibody Product AID - 10.1101/2020.09.17.302679 DP - 2020 Jan 01 TA - bioRxiv PG - 2020.09.17.302679 4099 - http://biorxiv.org/content/early/2020/09/18/2020.09.17.302679.short 4100 - http://biorxiv.org/content/early/2020/09/18/2020.09.17.302679.full AB - Host cell proteins (HCPs) are process-related impurities derived from host organisms, which need to be controlled to ensure adequate product quality and safety. In this study, product quality attributes were tracked for several mAbs under the intended storage and accelerated stability conditions. One product quality attribute not expected to be stability indicating is the N-glycan heterogeneity profile. However, significant N-glycan degradation was observed for one mAbs under accelerated and stressed stability conditions. The root cause for this instability was attributed to Hexosaminidase B (HEXB), an enzyme known to remove terminal N-acetylglucosamine (GlcNAc). HEXB was identified by liquid chromatography–mass spectrometry (LC-MS) based proteomics approach to be enriched in the impacted stability batches from mAb-1. Subsequently, enzymatic and targeted multiple reaction monitoring (MRM) MS assays were developed to support process and product characterization. A potential interaction between HEXB and mAb-1 was initially observed from the analysis of process intermediates by proteomics among several mAbs and later supported by computational modeling. An improved bioprocess was developed to significantly reduce HEXB levels in the final drug substance. A risk assessment was conducted by evaluating the in silico immunogenicity risk and the impact on product quality. To the best of our knowledge, HEXB is the first residual HCP reported to have impact on the glycan profile of a formulated drug product. The combination of different analytical tools, mass spectrometry and computational modeling provide a general strategy on how to study residual HCP for biotherapeutics development.Competing Interest StatementAll authors are employees of Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.