Development and manufacturability assessment of chemically‐defined medium for the production of protein therapeutics in CHO cells

Advantages of using internally developed chemically-defined (CD) media for cell culture-based therapeutic protein production over commercial media include better raw material control and medium vendor options, and most importantly, flexibility for process development and subsequent optimization needed for therapeutic protein production. Through several rounds of design of experiment (DOE) screening, and medium component supplementation and optimization studies, we successfully developed a CD basal medium (CDM) for CHO cell culture. The internally prepared liquid CDM demonstrated comparable cell culture performance to that from a commercially available control medium. However, when the same CDM formulation was transferred to two major commercial medium suppliers for manufacturing, cell culture performance utilizing these newly prepared media was significantly reduced compared with the in-house prepared counterpart. An investigation was launched to assess whether key medium components were sensitive to large-scale preparation of the final bulk media by the vendors. Further work necessitated the reformulation of the original CDM formulation into a core medium that was suitable for large-scale media manufacturing. The modified preparation of the core medium with two separate supplements to generate the final CDM was able to recover the expected cell culture performance and monoclonal antibody (mAb) productivity. Confirmation of cell culture robustness in cell growth and production was corroborated in two additional mAb-expressing cell lines. This work demonstrates that a robust CD medium is not only one that performs during the development stage, but also one that must be reproducible by commercial media vendors.