Differences in mAb Galactosylation Caused by the Leaching of Manganese Ions from Different Bioreactors

Protein N-glycosylation is one of the critical quality attributes of monoclonal antibody (mAb). Evaluating its scalability and batch-to-batch consistency is essential for ensuring process robustness and product safety and efficacy.

This study revealed that Project A exhibited significant scale differences in galactosylation ratio during process development and scale-up, with galactosylation levels in 2 L bioreactors being significantly greater than those in shake flasks and 200 L single-use bioreactors. We investigated the cause of this phenomenon and determined that the elevated galactosylation in 2 L bioreactor was due to the leaching of 0.05 μM to 0.06 μM manganese ions from the stainless-steel components in the 2 L glass bioreactor. These scale differences can be eliminated by adding 0.2 μM MnCl₂ · 4H₂O. Second, for projects with lower galactosylation levels, this paper suggests the use of shake flasks instead of bioreactors to guide the process scale-up of mAb glycosylation, thereby reducing trial-and-error costs and the production costs associated with replacing glass bioreactors with single-use bioreactors. Notably, the scale differences in mAb galactosylation observed in Project A do not apply to Project B, which showed no scale effect, indicating that this phenomenon may be more applicable to cell lines that are more sensitive to metal ions.

These findings demonstrate that metal ion leaching presents a substantial challenge to the process consistency of mAb. We have proposed a series of targeted and practical solutions to address the issue of "equipment and material leaching" during the production of mAb glycosylation amplification.