Enhanced CA15-3 Production Using Microcarrier-Based ZR75-1 Cultures

Abstract

Fujirebio Diagnostics AB (FDAB) produce tumour markers for clinical diagnostics, including CA15-3, which is used to monitor breast cancer. Currently, CA15-3 is produced using ZR75-1 cells cultured in roller flasks, a manual, time-consuming process with limited scalability. To improve this, there is growing interest in transitioning to bioreactor-based systems using microcarriers, which offer higher surface area-to-volume ratios suitable for adherent cell growth. This thesis explores whether microcarrier-based cultivation can improve CA15-3 production and serve as a scalable alternative to the roller bottle process. ZR75-1 cells were cultured on various microcarriers (CultiSpher G, Corning Enhanced Attachment, BioNOC II, and Fibra-Cel) in spinner flasks, and antigen levels (CA15-3, CA125, and CEA) were monitored. Attachment efficiency, cell density, and viability were also assessed. CultiSpher G showed the best performance and was used in bioreactor trials with perfusion. Peak productivity in spinner cultures reached 23 kU/L/day, about 167% higher than estimated roller flask levels. In contrast, bioreactor productivity reached 3.7 kU/L/day but was limited by premature perfusion and cell density loss. These findings demonstrate that microcarrier cultures, particularly with CultiSpher G, can significantly enhance CA15-3 production and have strong potential for scale-up. Further optimization of attachment, perfusion timing, and bioreactor conditions is needed. Transitioning to such systems could reduce manual handling at FDAB and improve process efficiency for future antigen production.