New high-throughput screening method for Chinese hamster ovary cell lines expressing low reduced monoclonal antibody levels: Application of a system controlling the gas phase over cell lysates in miniature bioreactors and facilitating multiple sample setup

Interchain disulfide bonds in monoclonal antibodies (mAbs) may be reduced during large-scale mAb production using Chinese hamster ovary (CHO) cells. This reaction lowers the mAb product yield and purity; however, it may be prevented by screening cell lines that are unsusceptible to reduction and using them in mAb production. Antibody reduction susceptibility may be cell line-dependent. To the best of our knowledge, however, an efficient method of screening reduction-unsusceptible CHO cell lines has not been previously reported. Here, we report a novel screening method that can simultaneously detect and identify mAb reduction susceptibility in lysates containing ≤ 48 CHO cell lines. This evaluation system was equally effective and generated similar results at all culture scales, including 250 mL, 3 L, and 1,000 L. Furthermore, we discovered that reduction-susceptible cell lines contained higher total intracellular nicotinamide adenine dinucleotide phosphate (NADPH) and NADP + concentrations than reduction-unsusceptible cell lines, regardless of whether they expressed immunoglobulin (Ig)G4 or IgG1. NADPH or NADP + supplementation in the lysate of reduction-unsusceptible cells resulted in mAb reduction. Application of the innovative CHO cell line screening approach could mitigate or prevent reductions in large-scale mAb generation from CHO cells.