mAb Capture by Multicolumn Chromatography
Tarpon Biosystems (www.tarponbiosystems.com) seeks to lower downstream purification costs by combining the technologies of chromatography media and columns in a novel format. With industrialization of biotechnology moving at a rapid pace, purification has become the dominant expenditure of biomanufacturing, now up to 65% of total downstream processing costs.
Tarpon, through a deal with BioFlash Partners (www.bioflashpartners.com), has exclusive access to a product line of prepacked, disposable, presanitized cartridges. BioFlach DFC™ are disposable-format chromatography cartridges for multicolumn chromatography applications. According to bioprocessing director Marc Bisschops, Ph.D., these cartridges can provide high chromatographic performance with virtually any medium and eliminate the labor-intensive task of cleaning and revalidating columns. “Moreover, the units are scalable from bench to large-scale manufacturing,” Dr. Bisschops stated.
The company has adapted traditional simulated moving bed technology (SMB) to address the requirement for sanitary processing in biotherapeutic manufacturing through the use of biocompatible, cost- effective disposable-format components such as valve cassettes. These items are proprietary to Tarpon, which has assigned them the product name of BioSMB™.
SMB was invented within the petroleum industry a half century ago and has since found application in pharma, the food industry, and in biotechnology. The rationale for adoption of SMB is to minimize solvent use and separation media in order to reduce the cost of operation as compared to traditional batch chromatography.
The modular column units can be assembled in series, so one feeds into the next, and products can be shunted off when their concentration is optimized. This operation mode provides a continuous chromatography system. BioSMB as a purification strategy is a volume-driven process, rather than mass driven.
This means that as cell culture titers continue to increase upstream, a BioSMB downstream system can handle varying titers efficiently without changing system hardware, simply by adding more disposable valve cassettes and cartridges. In a cost of goods analysis, taking into account production, labor, consumables, materials, and equipment, the BioSMB system was far superior to conventional separation, Dr. Bisschops concluded.
Another firm seeking to optimize its downstream processing technology is Boehringer-Ingelheim (www.boehringeringelheim.com). Dorothee Ambrosius, Ph.D., director of downstream development, and her coworkers are probing the limits of these manipulations. The company has a significant commitment to contract manufacturing of biologics, using both mammalian cells and microbial systems.
Dr. Ambrosius’ approach is to think commercially from the beginning of a biologics production project, with the aim of reducing the time to the clinical phase and shortening the overall time to market. Regarding the clinical phases, however, opposite goals have to be fulfilled. In early project phases, the primary focus is on fast-track development by means of platform technologies, whereas in later clinical phases, process robustness, scalability, and productivity are the key performance indicators.
A typical platform for mAb purification calls on Protein A affinity chromatography for capture, the decision being based on speed and yield. The details of the platform may require considerable customizing because of variations in the physical properties of individual antibodies as well as differences in impurity levels and other ancillary features of a particular batch. Indeed, Dr. Ambrosius showed that the optimum pH for elution off the protein A column can vary substantially from antibody to antibody. These preliminary investigations may reveal that a certain mAb candidate is not suitable for commercial exploitation.
In later clinical phases and for commercial manufacturing, the typical platform processes are not well-suited and do not meet the demands for robustness and process economy. Further optimization of a platform process often leads to significant improvements in yield, up to fourfold.
Hence, Boehringer Ingelheim has adopted a rapid, automated protein purification technology referred to as RAPPTor®, a screening system for any type of chromatographic resin in a 96-well format. This approach allows rapid testing of the loading, washing, and elution steps of different resins in parallel.
Subsequently, read-out tools have been transferred into the 96-well plates and automatically evaluated for the amount of protein by absorption at 280 nm and purity by different methods. Dr. Ambrosius endorsed the speed of this approach, citing an example in which only three days were required to obtain the best resin and conditions for high-yield antibody purification.