Biotherapeutic proteins usually are produced by either fed-batch or perfusion processes. Perfusion manufacturing can provide much higher levels of productivity than fed-batch systems can, thereby reducing production costs. A 2013 study showed that perfusion is more cost effective than fed-batch processes for most combinations of titers and production volumes (1). Moreover, because a perfusion process is much closer to steady state than is a fed-batch process, it often produces a more consistent product — especially for molecules that are sensitive…