Online monitoring of quality attributes (QAs) directly within the bioreactor can provide the basis for advanced modes of protein production including process intensification, smart manufacturing, and real-time release testing. The development of technologies to enable monitoring of QAs has been highly challenging due to the relative immaturity of commercial technologies for online analysis, generally low abundance of the attributes requiring highly specialized analytics not always amenable to automation, and the significant burden on development organizations to demonstrate the comparability and suitability of the online technologies resulting in low investment interest. In this study, we present for the first time a fully automated and highly flexible method for direct monitoring of QAs from the bioreactor. The method combines an automated sampling system and multi-dimensional (mD) LC-MS/MS technology to provide a means of quantifying post-translational modifications (PTMs) during the cell culture process and making real-time process decisions based on the resulting peptide mapping data. In doing so, a wide variety of PTMs can be identified and quantified including, but not limited to, oxidation, succinimidation, deamidation, isomerization, and glycosylation. The potential of this analytical workflow for the monitoring and trending of multiple attributes during cell culture production processes was first demonstrated with a standard IgG1 antibody over the production process. Then, the online workflow was applied to a complex format Fc-fusion protein to monitor sialylation. The ability to monitor sialylation offers a unique opportunity to develop process control schemes to ensure the final product meets quality specifications, showing the potential of this workflow in the context of online process analytical technology (PAT).
Keywords: Bioreactor; Fc-fusion protein; Quality attributes; Real-time monitoring; Sialylation.
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