Genetic Engineering & Biotechnology News

SEP15 2017

Genetic Engineering & Biotechnology News (GEN) is the world's most widely read biotech publication. It provides the R&D community with critical information on the tools, technologies, and trends that drive the biotech industry.

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8 | SEPTEMBER 15, 2017 | chromatography provides unique purification, particularly through the combination of multiple media with orthogonal separations. MilliporeSigma has demonstrated how these two modes may be used together to clear host-cell proteins (HCPs), antibody fragments, and low-molecular-weight impurities from solutions of monoclonal antibodies (mAbs). Recoveries higher than 85% and reduction of HCPs to below 10 ppm suggest that the flow-through approach may be adapted to existing (and new) mAb downstream opera- tions without compromising quality or process economics. "The operations may be positioned in numerous spots," Bulpin explains, "such as before the Protein A step to remove species that may typically foul the Protein A capture media, after low-pH virus inactivation to remove precipitated material, as a replacement train for polishing to remove impuri- ties to attain purity targets, or before virus filtration (to increase loading capacity). Regardless of the process proximity, Protein A capture would still be necessary." For example, MilliporeSigma's CR40 carbon-based depth filter re- moves HCPs, DNA, leached Protein A, mAb fragments, cell culture media components, and other impurities. In a study published that year, research- ers demonstrated that a combination of anion- and cation-exchange col- umns work for the flow-through chro- matography component. Combined, the ion-exchange media are expected to clear leached Protein A, protein aggregates, HCPs, DNA, and virus to levels acceptable for lot release. Productivity vs. Time The collaboration between LEWA, whose specialty is precision pumps and systems for biopharmaceutical production, and ChromaCon (con- tinuous chromatography) illustrates the breadth of expertise demanded for large-scale implementation of continu- ous purification. ChromaCon AG holds patents for CaptureSMB ® (2C–PCC), a two- column continuous chromatography process with dynamic process control, and markets the Contichrom ® CUBE benchtop two-column fast protein liq- uid chromatography (FPLC) lab-scale purification systems. Contichrom CUBE runs CaptureSMB and two other twin column countercurrent processes for polishing membranes and columns, in addition to two-step connected batch and traditional single-column batch purification. CaptureSMB ("capture" using "simulated moving bed" technol- ogy) was developed by ChromaCon, and ETH Zürich is validating Cap- tureSMB and other continuous bio- process technologies in the context of end-to-end continuous integrated bioprocessing of mAbs. CaptureSMB performance relies on the optimized timing of subpro- cesses using just two columns. Other systems, with three to eight columns, are less flexible in terms of flow rates, and they use more complex hardware. CaptureSMB-based processes rapidly achieve steady state by the time mate- rial exits the first column. Dynamic process control, AutomAb ® , is embed- ded in CUBE's process-control software to keep processes at optimal set points. EcoPrime ® Twin LPLC, the fam- ily of chromatography systems Continuous Bioprocessing Is Coming Continued from page 6 CO N T I N U O U S B I O P R O C E S S I N G ➜ Most commercial cell-retention systems, the basis of continuous cell culture, operate at bench scale and higher volumes, but are unsuit- able for volumes below two or three liters, where process developers are accustomed to working. Yet process development volumes for batch cultures are generally trending downward, with the benefits of reduced media and materials usage, a higher degree of parallelism, and lower costs. By contrast, spin filters, which are still available and used in re- search labs, lack upward scalability. "Since spin filters are unavailable at large scale, process developers are unable to extrapolate results beyond the benchtop," explains John Poppleton, marketing director at Applikon Biotechnology. "Spin filters also require extensive optimization, and they clog upon extended use. Thus, the advantages of long-term perfusion cultures are lost." Applikon's Biosep cell-retention system is a nonfouling device that separates trapped cells from expressed protein product through acoustics rather than size. Biosep allows continuous harvest from a perfusion culture, while retaining cells within the bioreactor at an op- timal concentration of approximately 100 million cells per milliliter. n Upstream Scalability Continous harvest from perfusion culture may be carried at at laboratory scale with Applikon Biotechnology's Biosep cell-retention system.

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