Unraveling what makes a monoclonal antibody difficult‐to‐express: From intracellular accumulation to incomplete folding and degradation via ERAD

• DOI: 10.1002/bit.27196
• Publication Date: 2019-10-21T08:24:50Z
• Authors: Sven Mathias; Anna Wippermann; Nadja Raab; Nikolas Zeh; René Handrick; Ingo Gorr; Patrick Schulz; Simon Fischer; Martin Gamer; Kerstin Otte
• Keywords: Endoplasmic-reticulum-associated protein degradation

Abstract Although most therapeutic monoclonal antibodies (mAbs) can routinely be produced in the multigram per litre range, some mAb candidates turn out to difficult‐to‐express (DTE). In addition, class of more complex biological formats is permanently increasing and mammalian expression systems like Chinese hamster ovary (CHO) cell lines show low performance. Hence, there an urgent need identify any rate limiting processing step during cellular synthesis. Therefore, we assessed intracellular location DTE antibody mAb2 by fluorescence electron microscopy (EM) revealed accumulation antibody, which led aberrant morphology endoplasmic reticulum (ER). Analysis underlying mechanisms that neither aggregation nor assembly, but folding represented reason for hampered secretion. We identified disulfide bridge formation within light chain (LC) was impaired due less recognition protein isomerase (PDI). As a consequence, molecule degraded intracellularly ubiquitin proteasome system via ER‐associated degradation (ERAD). This study with continuous emergence candidates, special attention needs drawn optimization processes ensure manufacturability.