The biopharmaceutical industry generally acknowledges that upstream and downstream aspects of drug-substance manufacturing are experiencing a capacity mismatch. Today, many recombinant proteins can be produced at expression titers of 3 g/L, with some yields exceeding 10 g/L. Such titers represent 100-fold increases in production capability compared with values from twenty years ago (1, 2). Increases in cell-culture density and improvements to perfusion-mode bioreactor systems hold promise for increasing yields further still. Such developments, combined with the broad availability of concentrated…