Discussion

An optimized and transferable process was developed in the 2- and 5-L glass vessels by monitoring, controlling, and adjusting process parameters such as pH, temperature, and partial pressure of carbon dioxide (pCO₂). The final process, a 14 day fed-batch culture with a day 2 feed of 12% of the working volume, a temperature shift mid-culture, and a pH drift after day 9 when necessary, was transferred to 50-, 250- and 1,000-L stirred-tank single-use bioreactors (SUBs). The performance of the optimized process was comparable across all scales, determining that the HyClone SUB was a suitable disposable bioreactor for manufacturing at Acceleron.

In addition to implementing disposable bioreactors, fiber optic dissolved oxygen probes and sensors were evaluated. Autoclavable probes from both PreSens and Finesse were compared to the traditional polarographic dissolved oxygen probes, and the disposable sensor from Finesse was also evaluated. Although additional studies need to be performed, initial results showed that the fiber optic technology used in the disposable sensors was comparable to the technology used in the traditional sensors and was feasible for implementation in Acceleron's biopharmaceutical manufacturing process.

REFERENCES

1. Trummer E, Fauland K, Seidinger S, Schriebl K, Lattenmayer C, Kunert R, et al. Process parameter shifting: Part I. effect of DOT, pH, and temperature on the performance of Epo-Fc expressing CHO cells cultivated in controlled batch bioreactors. Biotechnol Bioeng. 2006 Aug 20;94(6):1033–44.