(630e) Model-Based Insights on the Effect of Bioreactor pH and Temperature on N-Linked Glycosylation of Mabs Produced By CHO Cells

Optimization of the monoclonal antibody (mAb) bio-manufacturing process requires efforts in cell line development, media formulation, process monitoring, process control and determining optimal bioreactor operating conditions while meeting critical quality attributes (CQAs) such as those pertaining to N-Linked glycosylation, mAb aggregation and mAb fragmentation [1]. Quality by design (QbD) guidelines set by the FDA emphasizes the need to establish the relationship between process parameters and CQAs when designing a bio-manufacturing process [2]. Choosing the correct pH and optimizing temperature shift strategies is important for bioreactor operation as it can affect N-Linked glycosylation of mAbs, cell growth rate and titer production rate [3, 4]. There is evidence in the literature based on model based investigation of CHO cell-based processes that addition of manganese and galactose has substantial effects on N-Linked glycosylation of the mAbs [5]. However, the literature on model-based efforts to study the effect of bioreactor operating parameters such as temperature and pH on N-Linked glycosylation of mAbs is limited. The effect of such parameters on glycosylation is usually cell line dependent. Hence, more model based efforts can provide insights into developing general trends. Design space evaluation of Temperature and pH is important while designing a bio-manufacturing process. Computational tools such as that presented in this work will provide a platform to do this while utilizing an approach that is in line with the QbD guidelines.
Investigation into process parameters influencing the mAb bio-process was done for a CHO cell line producing a recombinant mAb biosimilar for Trastuzumab by varying pH and Temperature during mid-exponential phase of cell growth to identify metabolic differences that may influence mAb quality. Key metabolites such as glucose, lactate, ammonia as well as extracellular amino acid concentrations were measured along with mAb titer and N-linked glycosylation pattern. A kinetic model was developed to describe the effects of pH and temperature on CHO cell growth, titer production, ammonia profiles and consumption of glucose, aspartic acid and asparagine. An N-linked glycosylation model from the literature [6] was modified to include the effects of pH and temperature and subsequently integrated with the kinetic model for metabolism. Parameter regression was carried out to determine the kinetic and glycosylation model parameters. Sensitivity analysis provides insights into the effect of temperature and pH on the effect of different enzymes in the glycosylation pathway. This model here can be used to improve the understanding of bioreactor operation by capturing the dynamic profile of the protein glycosylation process and further guiding the production of high productivity and high-quality mAb product.
References
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