title: An XBP-1 dependent bottle-neck in production of IgG subtype antibodies in chemically defined serum-free Chinese hamster ovary (CHO) fed-batch processes.
abstract: The optimization of production processes for therapeutic antibodies is a continuing challenge in pharmaceutical biotechnology. Although it could be demonstrated that vector design and host cell engineering can improve transcriptional and translational efficiency and thereby result in generation of high producer cell lines, it is not clear whether introduction of transgenes that regulate protein transport or affect post-translational modifications could further improve such industrial processes. Here, we show that heterologous expression of the transcription factor X-box binding protein-1 (XBP-1) can lead to an increase in endoplasmic reticulum (ER) content and specific therapeutic antibody productivity of Chinese hamster ovary (CHO)-DG44 cells in inoculum suspension cultures. This effect translates into 40% increased overall antibody titers in a fed-batch format where cells are grown in chemically defined serum-free media. Protein-A purified antibody products from mock-transfected cells and XBP-1 transfected cells were found to be of comparable quality with regard to glycosylation pattern and physicochemical characteristics. The data demonstrate the potential of XBP-1 engineering to improve mammalian cell culture production processes to yield high amounts of a therapeutic protein product of desired quality.
authors.affiliation: Boehringer Ingelheim Pharma GmbH & Co. KG, BP Process Science, Birkendorferstrasse 65, 88397 Biberach an der Riss, Germany.
authors.forename: Eric
authors.initials: E
authors.lastname: Becker
authors.forename: Lore
authors.initials: L
authors.lastname: Florin
authors.forename: Klaus
authors.initials: K
authors.lastname: Pfizenmaier
authors.forename: Hitto
authors.initials: H
authors.lastname: Kaufmann
mesh_terms: D000818:Animals; D000906:Antibodies / Q000378:metabolism*; D015153:Blotting, Western; D016466:CHO Cells; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods; D006224:Cricetinae; D003412:Cricetulus; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis*; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014162:Transfection; D000071717:X-Box Binding Protein 1
chemical_list: D000906:Antibodies; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins; D007074:Immunoglobulin G; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human