(204d) Design of a Scalable Continuous Precipitation Process for the High Throughput Capture and Purification of High Titer Monoclonal Antibodies
AIChE Annual Meeting
2010
2010 Annual Meeting
Food, Pharmaceutical & Bioengineering Division
Bioseparations and Downstream Processing
Tuesday, November 9, 2010 - 9:06am to 9:24am
Continuous improvements in cell culture technology have driven bioreactor titers for monoclonal antibodies to unprecedented levels. The biotechnology industry is operating under a new paradigm: mAb titers exceeding 10 g/L ? once considered a benchmark for future productivity ? are no longer an uphill climb. As a consequence, the emphasis on increasing process efficiency has been shifted to downstream purification steps. To maximize throughput downstream, we precipitate monoclonal antibodies with a synergistic combination of polyethylene glycol and zinc chloride as an alternative to bind-and-elute chromatography. Our initial efforts focused on optimizing precipitation conditions using an upfront concentration step, followed by precipitation in stirred batch reactors. However, antibody titers greater than 2 G/L presented challenges in obtaining adequate precipitate yield, morphology, and size distribution when scaling-up the batch precipitation process. In addition, the scaled batch precipitation process did not lend itself to precipitate separation via continuous disc stack centrifugation. Thus, we developed a continuous precipitation process using static mixers with in-line additions of zinc chloride and polyethylene glycol, to provide a more consistent, scalable mixing environment (e.g. predictable scaling behavior, consistent precipitate morphology and size distributions). Techniques for optimal precipitate isolation (microfiltration, depth filtration, centrifugation) were then evaluated. The continuous precipitation process was successfully integrated into a downstream purification train consisting of precipitate isolation, precipitate storage, and downstream purification through two flow-through chromatography steps designed to maximize process throughput (mass loadings) and impurity reduction.