Bioreactor productivities are highly dependent on the process used to cultivate mammalian cells. These productivities directly affect the manufacturing plant capacity, and thereby the economics of production of monoclonal antibodies (MAbs). Historically, companies have chosen bioreactor process strategies that emphasize simplicity of scale-up at the expense of productivity, and conducted manufacturing using well-characterized and relatively straightforward batch processes. Such processes have successfully produced small or moderate quantities (ranging from ~100 g to ~ 1 kg per lot) of the desired antibody. Given the anticipated demand for large-scale quantities of MAbs (and the high stakes for the companies investing in these new biological entities), it is worthwhile to revisit these past selection strategies and see if — and under what conditions — they remain optimal today…