Titer of trastuzumab produced by a Chinese hamster ovary cell line is associated with tricarboxylic acid cycle activity rather than lactate metabolism

• Two contrasting cell lines A and B were characterized by metabolomic analysis.
• High antibody titer in cell line A was due to high TCA cycle activity.
• Different defucosylation levels were not due to different GDP-fucose levels.
• Higher covalent aggregate content in cell line A was due to high oxidative stress.

Achieving high productivity and quality is the final goal of therapeutic antibody development, but the productivity and quality of antibodies are known to be substantially dependent on the nature of the cell lines expressing the antibodies. We characterized two contrasting cell lines that produce trastuzumab, namely cell line A with a high titer and a low aggregate content and cell line B with a low titer and a high aggregate content to identify the causes of the differences. We observed the following differences: cell growth (A > B), proportion of defucosylated oligosaccharides on antibodies (A < B), and proportion of covalent antibody aggregates (A > B). Our results suggest that the high monoclonal antibody (mAb) titers in cell line A is associated with the high proliferation and is not caused by the lactate metabolism shift (switching from lactate production to net lactate consumption). Rather, these differences can be accounted for by the following: levels of tricarboxylic acid cycle intermediates (A > B), ammonium ion levels (A ≤ B), and oxidative stress (A > B).