WuXi Biologics has achieved cell culture productivity for an Fc-fusion protein of 51 g/L and is confident it can be scaled up to 4,000 L. Single-use bioreactors are limited to 4,000 L in capacity (though many biomanufacturers put 2,000 L as their upper limit). Using these bioreactors with mammalian cell line tech is problematic for large-scale commercial use due to the generally low productivity of such expression systems, usually sub-10 g/L. But Chinese contract development and manufacturing organization (CDMO) WuXi…