Get access

A mechanistic understanding of production instability in CHO cell lines expressing recombinant monoclonal antibodies

Authors

  • Minsoo Kim,

    1. Department of Chemical and Biological Engineering, University of Sheffield, Mappin St., Sheffield S1 3JD, UK; telephone: +44-114-222-7505; fax: +44-114-222-7501
    Current affiliation:
    1. Present address: Cell Science Team, R&D Center, Celltrion Inc., Incheon 406-840, South Korea.
    Search for more papers by this author
  • Peter M. O'Callaghan,

    1. Department of Chemical and Biological Engineering, University of Sheffield, Mappin St., Sheffield S1 3JD, UK; telephone: +44-114-222-7505; fax: +44-114-222-7501
    Search for more papers by this author
  • Kurt A. Droms,

    1. BioTherapeutics Research and Development, Pfizer Corporation, 700 Chesterfield Parkway West, Chesterfield, Missouri 63017
    Search for more papers by this author
  • David C. James

    Corresponding author
    1. Department of Chemical and Biological Engineering, University of Sheffield, Mappin St., Sheffield S1 3JD, UK; telephone: +44-114-222-7505; fax: +44-114-222-7501
    • Department of Chemical and Biological Engineering, University of Sheffield, Mappin St., Sheffield S1 3JD, UK; telephone: +44-114-222-7505; fax: +44-114-222-7501.
    Search for more papers by this author

  • Minsoo Kim and Peter M. O'Callaghan contributed equally to this work.

Abstract

One of the most significant problems in industrial bioprocessing of recombinant proteins using engineered mammalian cells is the phenomenon of cell line instability, where a production cell line suffers a loss of specific productivity (qP). This phenomenon occurs with unpredictable kinetics and has been widely observed in Chinese hamster ovary (CHO) cell lines and with all commonly used gene expression systems. The underlying causes (both genetic and physiological) and the precise molecular mechanisms underpinning cell line instability have yet to be fully elucidated, although recombinant gene silencing and loss of recombinant gene copies have been shown to cause qP loss. In this work we have investigated the molecular mechanisms underpinning qP instability over long-term sub-culture in CHO cell lines producing recombinant IgG1 and IgG2 monoclonal antibodies (Mab's). We demonstrate that production instability derives from two primary mechanisms: (i) epigenetic—methylation-induced transcriptional silencing of the CMV promoter driving Mab gene transcription and (ii) genetic—progressive loss of recombinant Mab gene copies in a proliferating CHO cell population. We suggest that qP decline resulting from loss of recombinant genes is a consequence of the inherent genetic instability of recombinant CHO cell lines. Biotechnol. Bioeng. 2011;108: 2434–2446. © 2011 Wiley Periodicals, Inc.

Ancillary