Biopharmaceutical drug-substance (DS) manufacturing consists of several unit operations. Upstream production includes multiple steps in growing bacterial or mammalian cells in culture. Upstream activities are followed by a series of downstream processing units including chromatography and filtration steps for removing impurities and purifying a therapeutic molecule (1). All these operations are inherently complex because of the natural variability associated with growing living cells and the intricacy of purification techniques used for collecting biological products. The US Food and Drug Administration…