(238a) Towards Scaled-up Biologics Purification By Using Continuous Crystallization

Monoclonal antibodies (mAbs) have been used for diagnosis, disease treatment, and research for years. With the recent COVID-19 pandemic, the ability of antibodies to recognize and treat this particular infection has increased interest by researchers in the manufacturing of mAbs. Despite of their broad usage from treatment of various diseases to measurement of hormone levels, their high cost remains due to the existing purification processes being expensive. Typical industrial estimates attribute 50 to 70% of the cost of goods for a typical mAb process to being associated with the purification processes.

This presentation describes a methodological approach to develop a continuous precipitation and crystallization system for mAbs as a means of eliminating the most expensive purification step while providing an effective method for scaleup. Our methodology can be described as conducting micro-scale scale experiments to investigate the crystallization behavior and to construct the phase diagram followed by small-scale experiments to investigate the crystallization kinetics such as induction time and effects of process variables such as mixing. Crystallization of commercial mAbs are achieved by using only salt within 45 minutes in 1.5 mL after constructing the phase diagrams via micro-well experiments where the induction time was around 12 hours. Then the process is scaled up to a tubular precipitator followed by a tangential flow filter and continuous 2-stage mixed suspension–mixed product removal (MSMPR) crystallizer with 25 mL volume for each MSMPR with pressure-driven transfer. Pressure, temperature, inlet pH, flow rates, salt concentration, and the liquid-phase concentration are recorded along with the slurry density by using Raman spectroscopy. Off-line characterization tools such as high-pressure liquid chromatography (HPLC) and Raman microscopy are used to validate the use of crystallization in mAbs purification. Although continuous mAbs crystallization is attractive due to being readily scalable, inexpensive, and fast, this promise is only achievable if the processes can be operated at high yield. Recent studies from this work are aimed to maximize the yield by conducting further experiments and developing the process model for process optimization.