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Feature Articles : Feb 1, 2007 ( )
Disposables Win Downstream
Single-Use Processes Replace Hard-Piped Operations for Many Companies!--h2>
Last year was a banner year for uptake in single-use products in biomanufacturing, but not so much for novel technology. “There’s nothing out there that wasn’t, in one form or another, in 2005,” says Vijay Singh, Ph.D. president, Wave Biotech LLC (www.wavebiotech.com). “What’s really changing is the acceptance level of disposables.”
Disposability confers well-known advantages of less cleaning and cleaning validation, but as disposables trickle down into mainstream bioprocessing, manufacturers who adopt these products are experiencing greater flexibility. Single-use products are replacing hard-piped processes and unit operations. Even facility engineers are figuring disposables into their plant designs.
Dr. Singh sees radical changes in his customer base since last year, with an increase in the percentage of customers using disposables for production rising from 20–30% to more than 60%. This suggests that fewer customers view disposables as a risk. And with the maturation of single-use products, customers are demanding a wider range of services to support them. Wave, for example, has tripled its validation and regulatory staff.
Improvements in cell culture product titers have created an interesting dynamic in bioprocessing, where “bigger is better” was the motto for many years. Processes are shrinking, thus making disposable equipment that was once suitable only for small, experimental batches appropriate for manufacturing. Wave’s largest-volume bioreactor bag holds 500 liters—quite small by production standards. The company plans to introduce a 1,000-L product early in 2007.
Manufacturers of niche or low-volume products have especially benefited from rising titers and the availability of disposable bioreactor equipment. Wave’s disposable Flex reactors are catching on for microbial fermentations, and a Danish manufacturer of smallpox vaccine uses six Wave Bioreactors to make a batch. Dr. Singh sees vaccines as a growth market for disposables, especially for a fully disposable, all-inclusive vaccine manufacturing kit.
According to Paul Priebe, who manages process filtration and disposables at Sartorius (www.sartorius.com), “virtually all” bioprocessors are specifying or considering disposable equipment. Priebe sees the trend as part of a natural evolution, as more and more unit operations become available in disposable formats. He notes that enabling technologies, particularly membrane chromatography, sterile connecting, welding and sealing devices, aseptic agitation systems, and disposable sensors are paving the way for robust, integrated unit operations with fully disposable fluid paths that provide the benefits of disposability without sacrificing performance. Moreover, systems are evolving for complete disposability in traditionally hardware-intensive unit operations.
“This started several years ago with disposable bioreactors, but now traditional hardware and systems companies are getting into the game,” says Priebe. Sartorius recently partnered with Wave AG (www.wavebiotech.ch) to combine the Sartorius Biostat control system with a disposable, rocking bioreactor bag. The Sartorius system incorporates two disposable optical chemical sensors for pH and dissolved oxygen, both with feedback control, controllers for oxygen, nitrogen, CO2, and mass flow, and a pressure transmitter to monitor and control gas flow.
Disposables are already ubiquitous in media and buffer preparation, crossflow filtration, concentration and diafiltration, low-pH viral inactivation, and ion exchange chromatography. Disposable separations, in the form of ion exchange membrane chromatography, are fine for removing trace contaminants.
Unfortunately, disposable affinity chromatography remains elusive and probably will be for several years. One workaround may be to switch to relatively low-cost resins, for example substituting hydroxyapatite for Protein A. Developing chromatography media inexpensive enough to use only once would probably entail a tradeoff in capacity, but the trend of high protein titers, which continues unabated, creates a situation where media capacity will struggle to catch up, or keep up, with titers.
“It’s a race between capacity and titers,” says Rich Richieri, Sr. vp of manufacturing for Avid Biosciences, a subsidiary of Peregrine Pharmaceuticals (www.peregrineinc.com). And at least for now, titers are winning.
Buffer prep is the operation where disposables save the most time and generate the most economic payback for companies like Avid. In the past year the company replaced a Q resin column, which required packing, qualifying, and cleaning, with a membrane absorber. Avid is also beginning to look closely at disposable bioreactors, where the company expects to see savings equal to or greater than that for buffers. “Single-use reactors are going to be a game changer for contract manufacturers,” Richieri says. “Not just because they’re disposable, but for their impact on process footprint and facilities.”
For unit operations where single use is not economically feasible, such as affinity chromatography, Priebe believes that disposables can play a support role. Protein A affinity chromatography may be too expensive to use only once, but treating bioprocess fluids with a flow-through disposable chromatography device before the capture step dramatically increases the efficiency of Protein A media. And the column may be connected to a skid that utilizes a disposable fluid path.
“These support equipment designs will allow processors to utilize and benefit from disposables while maintaining much of the feel and control that they have had in traditional systems,” Priebe adds.
Denise DiTomasso, technical marketing manager at SAFC Biosciences (www.safcbiosciences.com), reports that while adoption of disposables in downstream processing is rising, manufacturers remain skeptical for some applications where single-use surfaces come into contact with a “live” protein. Such concerns arise, to some degree, from the relative lack of regulatory guidance on proper use of disposable equipment.
“We can demonstrate product safety to our satisfaction, but what will the FDA ask for or expect? Manufacturers are doing the best they can, but there are still many unknowns.” She cites initiatives from the Bioprocess Systems Alliance, an organization of vendors and suppliers, to develop workable guidelines. “But in the end regulatory agencies will need to provide input,” she notes. SAFC sells sterile, single-use, polyethylene process kits based on its BIOEAZE™ bags, which range in size from 1 L up to 1,000 L.
Systems vs. Components
Increasingly, end-users are looking for design, technical, and validation support for integrated single-use systems, rather than for individual components. The environment where manufacturers order tubing from one vendor, bags from another, a mixing system from yet another, assemble systems in a sterile enclosure, and all the while keep abreast of material compatibility and regulatory status, are fading fast.
Integrators who can put the pieces together in custom, validated formats are becoming the leaders in the disposables marketplace. DiTomasso compares the situation with that of media development and formulation. “Biomanufacturers can do it themselves, but hardly ever do any more.”
Meissner’s (www.meissner.com) DPS™ (Disposable Processing System) incorporates what the company calls “prevalidated building blocks” from the company’s disposable products: pre-assembled, single-use filter, tubing and flexible biocontainer system incorporate the end user’s choice of Meissner’s sterilizing-grade EverLUX™ PES (polyethersulfone), STyLUX® PES or SteriLUX® PVDF membrane filters. Filter configurations include capsules, UltraCap® high-capacity capsules, or UltraCap® H.D. (heavy-duty) high-capacity capsules. DPS assemblies are customized to user’s requirements for processing 5 L to 2,000 L of biopharmaceutical process or products through sterile filling, dispensing, sampling, transporting, and mixing through temporary hold and long-term storage, with both bulk and purified products.
Millipore (www.millipore.com) has been focusing on tools to integrate disposable equipment such as sterile-to-sterile connectors. The company’s acquisition last year of Newport Biosystems, a disposable bio-bag manufacturer, adds a new dimension to Millipore’s single-use product line.
One upshot is a new film technology, PureFlex, a high-purity, medical-grade, monolayer, coextruded film that provides strength, flexibility (with maximum resistance to flex-crack), gas barrier performance, and inert contact. In June, 2006, Millipore introduced a new line of Mobius™ disposable, self-contained assemblies for tangential flow filtration, which are used with the company’s Pellicon® disposable TFF filtration cassettes. Together, the Newport bags and Mobius products position Millipore among the integrator vendors.
For Bob Smith-McCollum, director of marketing, North America for Stedim Biosystems (www.stedim.com), the advance of disposable biomanufacturing is evident in growing customer confidence in manufacturing and quality capabilities of vendors and integrators, and the application of single-use products in more-complex applications, further downstream in the manufacturing process. “Single-use applications are becoming more demanding technically, and systems are in contact with components and products of higher value, such as bulk drug substance.”
Increasingly, disposable system vendors are valued as partners for design, implementation, and validation, in addition to selling the equipment. Stedim has established fee-for-service validation to expedite customer-specific extractables/leachables, chemical compatibility, and other studies on a for-fee basis. Its new disposable products include models of the Flexel® 3D Impeller Mixing system, one of which is targeted for dissolution of powders, and the other for liquid-liquid mixing and blending.
As these trends continue, users will demand greater sophistication from disposable systems. “A good example is the growing interest in single-use, non-invasive sensors for a variety of single-use applications from cell culture to downstream purification.”
Technology Breeds Confidence
According to Juliette Schick, Ph.D., president of SciLog (www.scilog.com), end users are interested in equipment that can either be disposed along with the process ware, or reused under the right circumstances.
This is especially true in R&D, where cleaning and reusing a disposable product is acceptable. Some of SciLog’s customers have cleaned and reused the firm’s disposable sensors more than 10 times without loss of calibration.
Single-use quality and functionality need to be equivalent to, or even surpass, existing technology yet be modestly priced. Success entails drawing on and combining advances in materials, electronics, and fabrication into novel products. “New disposable products do not simply try to adapt 1960s technology to a disposable housing,” states Dr. Schick.
SciLog’s disposable sensors are a good example. The low-cost, precalibrated devices incorporate “smart” identifiers and calibration values in embedded memory. This information may be compiled, along with the data from a process run, into a spreadsheet or graph in real-time
In 2006 SciLog introduced the SciCon disposable, precalibrated conductivity/temperature sensors and monitor, and in 2007 the SciPres disposable, precalibrated pressure sensor/monitor with built-in alarms and calculation of differential pressure and transmembrane pressures. Also this year, the company introduced SciTemp, a high-precision temperature sensor and monitor. All three new products are disposable, precalibrated, and operate in-line.
Research Markets Also Benefit
Disposables are also catching on in research and development. New Brunswick Scientific (www.nbsc.com) now offers two versions of its low-cost disposable FibraStage™ cell culture system. In addition to the original batch system, the company has introduced a new model with pump module for continuous media exchange for production of research quantities of proteins, viruses, or cell mass from anchorage-dependent or suspension cultures. FibraStage consists of 500-mL disposable bottles, presterilized and filled with FibraCel disks, a solid-support matrix providing a low-shear environment and high surface area for cell growth.
Gas exchange and media mixing occur inside the the FibraStage module, which compresses and expands the bottles, forcing media through the disk bed. Pumps simplify nutrient addition and waste removal, while reducing the potential for contamination during media replacement.
Other companies are working on small systems in which desktop-sized hardware holds one or more disposable bioreactors. Dasgip (www.dasgip.com) is developing a research-grade bioreactor with 5-mL disposable vessels under full control for nutrient addition, waste products, gases, temperature, and other parameters. And Biovest (www.biovest.com) employs its AutoVaxID to create personalized medicines for its clinical testing program. AutoVaxID uses a self-contained, disposable hollow-fiber bioreactor module, or “culture ware,” housed in a GMP-compliant cell growth instrument about the size of a liquid chromatography system.
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