Conclusion
In conclusion, clear differences in HCP profile were observed between steady state and non-steady state cultures, as well perfusion and fed-batch culture. Fewer HCPs were detected in SS perfusion process. This is likely due to the high viability and lower cell counts in steady state. Even though the level of HCPs in the final drug product would be very low (1-100 ppm), those trace amounts of difficult or problematic HCPs may effect on the quality attributes of mAb1. To characterize the HCPs potentially affecting mAb quality, the detailed analysis of HCPs in the culture supernatant of culture processing of mAb1 producing CHO cells was performed in this study.
HCPs that were present in HCCF from fed-batch and perfusion processes of mAb1 were identified and quantified using LC-MS approaches including lipases that cause mAb1 stability. Different profiles and levels of lipases were detected in the different cell culture processes. In perfusion process of mAb1, altered distribution of charged variant species may provide an opportunity to clear the lipases by downstream process. Our work demonstrates that future bioprocessing can be shaped by a deep understanding of the impact of cell culture process on specific product quality when we move from traditional fed-batch to next generation high productivity perfusion cell culture. A process specific ELISA assay is likely needed for perfusion process. Combining advanced downstream and analytical techniques in addition to tailored approaches to perfusion cultures can offer greater control over product quality, stability and ultimately the safety of biotherapeutics.
The authors would like to acknowledge contributions from the following: