During large-scale production of a monoclonal antibody product, we observed significant reduction of the antibody's interchain disulfide bonds. This reduction event culminated in lost product as the bulk failed to meet product quality specifications. Small-scale laboratory studies revealed that the cause of the reduction was due to mechanical shearing of the cells, which resulted in the release of cellular enzymes that in turn reduced the antibody product. To further investigate the mechanism, the cytosolic isoform of thioredoxin, TXN1, was knocked down by lentiviral-mediated RNAi to determine if inhibiting its expression and/or activity could attenuate (or prevent) antibody disulfide reduction. The results of these experiments provided the rationale to design a strategy to develop a host cell line that is devoid of antibody disulfide reduction and to further analyze how the thioredoxin pathway may be modulated during our CHO cell culture processes.

Molecular mechanism of antibody disulfide bond reduction in CHO cell culture processes

243rd National Meeting (2012)

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