By Cliff Mintz
Single-use, disposable products were first introduced to the biomanufacturing industry about a decade ago. Until recently, single-use manufacturers had to extol their benefits and virtues to convince biomanufacturers to consider trying them. However, today’s growing biopharmaceutical product diversity, increasing demand, and high development costs are forcing an increasing number of life sciences companies to incorporate single-use, disposable technologies into their biomanufacturing production trains.
The use of single-use, disposable products in biomanufacturing processes offers a number of advantages over traditional stainless steel systems — currently the industry standard. These include: 1) reduced capital investment in equipment and facility infrastructure; 2) fewer regulatory concerns and time, cost, and labor reductions in validation requirements for cleaning systems, including clean-in-place (CIP) and sterilize-in-place (SIP); 3) decreased risk of product cross-contamination; 4) quicker campaign turnaround times; 5) increased assurance of sterility; and 6) more flexibility in portability, scalability, and facility operations management. Other factors driving the adoption of single-use technologies include vastly improved cell culture protein yields; a trend toward development of increased potency, lower-dose biotechnology drugs; improved protein-based drug delivery systems; and a greater reliance on niche products in the personalized medicine and therapeutic vaccine industries.
Jeff Craig, global director of business development and marketing for ATMI Life Sciences, contends that, “Most, if not all, biomanufacturers are considering how to integrate single-use, disposable technologies into their manufacturing trains to improve operational efficiencies and cut costs.” He may be right — a 2008 survey conducted by BioPlan Associates, a company that tracks biomanufacturing trends, revealed that the disposable technology market is rapidly growing and single-use products are becoming increasingly popular. Steve Wilkowski of Dow Corning, a manufacturer of disposable silicon tubing, expects the size of the market to continue to grow 17% to 20% over the next few years “as more companies begin to recognize the portability, flexibility, and cost advantages offered by single-use products.”
Companies that manufacture single-use products continue to innovate and improve their products to meet customer needs and demands. Over the past five years, single-use, disposable products have been developed for every stage of the biomanufacturing process. Some of the products developed for upstream use include: disposable plastic bags, tubing and mixing solutions for preparation, storage and transfer of buffers and media, and disposable bioreactors and biosensors to grow host cells. For downstream processing, companies have developed disposable tangential and cross-flow filtration membranes and single-use chromatography cartridges for product capture, polishing, purification, and virus removal. Finally, several companies have introduced single-use, disposable solutions for sterile fill/finish operations. Uwe Gottschalk, VP of purification technologies at Sartorius AG, says, “The technology is available today to build an entire biomanufacturing production train using single-use, disposable products.” He adds, “In some cases, it may be preferable and the most cost-effective and appropriate choice — especially for production of clinical trials material.”
PREPARATION, TRANSFER, STORAGE OF MEDIA AND BUFFERS
“There is a lot of fluid transfer and storage in a typical biomanufacturing process,” says Dow’s Wilkowski. Therefore, it isn’t surprising that some of the first single-use products brought to market were disposable plastic storage bags, connectors, and tubing. Companies including Sartorius Stedim, Thermo Fisher Hyclone, and ATMI Life Sciences all offer a full array of disposable plastic bags and connectors for media/buffer preparation, storage, and transfer.
According to ATMI’s Craig, there are at least 15 to 25 mixing steps in a typical bioprocess train. Because of this, many single-use product manufacturers, including Thermo Fisher Hyclone, Sartorius Stedim, and Millipore, offer disposable bag-mixing systems that range in size from 5 to 3,500 L capacities. Other companies like Xcellerex and GE Healthcare/Wave also offer disposable bag-mixing solutions. Finally, ATMI Life Sciences offers five different mixing solutions ranging in capacity from 5 to 2,000 L that can be integrated and used at various stages of biomanufacturing.
While the use of disposable bag technologies can vastly improve operational efficiencies and reduce the risk of product cross-contamination, there is a growing concern among biomanufacturers about leachables and extractables that may appear in buffers, media, and product intermediates after prolonged storage in single-use bags. Approximately 75% of respondents in a 2009 BioPlan Associates’ survey indicated that leachables and extractables are a major concern that might restrict their use of single-use products. The anxiety of many biomanufacturers is being driven by the growing interest in leachables and extractables by the U.S. FDA and the possible effect of these substances on final product purity.
To address these concerns, several professional organizations, including the American Society of Mechanical Engineers Bioprocess Equipment (ASME BPE) plastic subcommittee and the Bioprocess Systems Alliance (BPSA) are trying to harmonize leachable and extractable guidelines and standards for single-use, disposable products. ATMI’s Craig says, “Leachables and extractables are a major concern for both customers and regulators. While most experts agree that they don’t pose serious safety problems, a lack of harmonized testing guidelines among single-use manufacturers inhibits product interchangeability by end users. Single-use manufacturers, ASME BPE, BPSA, and regulatory experts are working closely with the FDA to harmonize disposable leachable and extractable guidelines and standards.”
CELL CULTURE, BIOSENSORS, UPSTREAM PROCESSING
Major improvements in cell culture yields and upstream processing efficiencies have created a market for single-use, disposable bioreactor bags. ATMI Life Sciences, GE Healthcare/Wave, Sartorius Stedim, Thermo Fisher Hyclone, and Xcellerex make disposable bioreactor bags in various sizes and configurations.
Thermo Fisher Hyclone was the first to introduce the single-use, disposable bioreactor concept and offers various sizes of vertical, cylindrical bioreactor bags that are designed to fit into a stainless outer vessel support with a heating jacket and a disposable mixing mechanism. Aeration, mixing, and biosensor probes are introduced into the bag through welded elastomer sleeves. Sartorius Stedim and GE Healthcare/Wave manufacture bioreactor bags in a flat configuration agitated by the motion of a rocker platform. Like the Thermo Fisher Hyclone configuration, mixing, aeration, and probes are inserted into the Wave and Sartorius Stedim through welded bag ports. ATMI Life Sciences recently introduced a rectangular-shaped disposable bioreactor bag with a top-mounted agitator rod. Finally, Xcellerex manufactures a disposable bioreactor bag that fits into a support shell with a magnetically coupled bottom agitation system (stirred-tank) for mixing.
One of the major limitations of all of the disposable bioreactor bag systems is the reliance on conventional biosensor probes (developed for use in stainless steel systems) to measure bioreactor temperature, dissolved oxygen (DO), pH, conductivity, and osmolality. These probes must first be sterilized (via autoclaving) and then attached to penetration adapter fittings that are welded into bioreactor bags. Not surprisingly, this is a labor-intensive and time-consuming process that has the potential to compromise the integrity and sterility of single-use bioreactor bags. Because of this, several companies, including Finesse and Fluorometrix (recently acquired by Sartorius Stedim), have created single-use, membrane biosensors that can be added to or directly incorporated (during manufacturing) into single-use bioreactor bags.
Finesse manufactures disposable, fitting-based, autoclavable biosensors that use a combination of phased fluorometry and RFID (radio frequency identification) technology to measure and capture readouts for pH, DO, temperature, and cell density during upstream bioprocessing. Mark Selker, Finesse’s CTO, says, “Our disposable biosensor line of products is compatible with all of the single-use bioreactor systems available on the market today.”
In contrast, the biosensors manufactured by Fluorometrix are non-invasive, membrane sensors developed using optical fluorometric chemistries that can be directly incorporated into any disposable bioreactor bags. Govind Rao, a professor at the Center for Advanced Sensor Technology at the University of Maryland Baltimore County and a co-founder of Fluorometrix, says, “Because the sensors can be manufactured into any type of single-use bag, they are useful for both upstream and downstream applications.” Also, he suggested that the biosensors are “compatible with the FDA’s process analytical technology [PAT] initiative,” which aims to monitor and control biomanufacturing by measuring critical parameters throughout the manufacturing process.
Vastly improved cell culture product yields and technological advances in upstream bioprocessing are threatening to swamp the downstream capacity of many biomanufacturers. “Downstream processing bottlenecks represent the greatest challenge facing biomanufacturers today,” says Maik Jornitz, group VP at Sartorius Stedim North America.
Historically, downstream manufacturing had relied almost exclusively on resin-packed column chromatography for polishing, purification, and viral inactivation. While an increasing reliance on tangential flow and cross-flow filtration has helped improve downstream bioprocessing capabilities, the time, costs, and labor required for column cleaning and repacking and CIP and SIP for traditional filtration systems remain high. This has prompted several manufacturers to develop single-use, disposable solutions for membrane filtration and column chromatography.
Sartorius Stedim recently introduced single-use, disposable anion-exchange membrane adsorption cartridges which can be used for DNA and host cell protein removal or viral clearance. Likewise, Pall Corporation offers a similar disposable membrane product specifically designed for DNA removal. Other companies including GE Healthcare, Millipore, BioFlash Partners, and Tarpon Biosystems have developed prepacked and presanitized disposable-format chromatography columns. Most of these columns were designed for polishing applications except Tarpon’s, which can be also be used for the capture step in monoclonal antibody (MAb) purification. Sartorius’ Gottschalk says capture remains a major challenge and contributes to the downstream bottlenecks plaguing many MAb manufacturers. “There is growing pressure from our customers to improve downstream single-use, disposable products and make them more readily available,” he adds.
STERILLE FILL/FINISH DISPOSABLE SYSTEMS
“Sterile fill/finish is one of the most costly but frequently overlooked parts of the biomanufacturing production train,” says Jeff Jackson, PHL sales director at Bosch Packaging Technology North America. Recognizing this, Bosch developed a prevalidated, preassembled, and presterilized single-use, fill/finish system for the biopharmaceutical industry. All of the tubing, connectors, filling needles, and pump membranes were designed as single-use, disposable products. This provides fill/finish operators with unprecedented flexibility and the ability to reduce turnaround times and minimize the possibility of cross contamination at multiuse facilities. Early on, ATMI also recognized the importance of sterile fill/finish in the bioprocess production train and developed a single-use, disposable mixing system used for product formulation during fill/finish operations.
One of the major challenges facing the single-use, disposable industry is its impact on the environment. “While single-use technology can improve operational efficiencies, reduce facility turnaround times, and help cut labor and other costs, the disposal of the plastic waste generated by their use must be considered in the context of favorable environmental impact,” says ATMI’s Craig. “The biomanufacturing community is very aware and sensitive to the environmental questions surrounding single-use, disposable products and is actively discussing ways to creatively deal with these issues,” he adds. At present, approximately 60% of the companies using single-use products incinerate the plastic waste, 30% is buried in landfills, and about 10% use the waste as an alternative energy source. Many biomanufacturers contend that disposable technologies can help to reduce the biomanufacturing industry’s carbon footprint and also curb water usage by minimizing CIP and SIP activities.
The lack of defined leachable and extractable standards for disposable products poses regulatory challenges and limits the interchangeability options for many end users of these products. This frequently forces biomanufacturers that use disposable products to rely on a single supplier — something that could adversely affect production if the supplier experiences financial or manufacturing problems. With this in mind, biomanufacturers are pushing single-use companies and regulators to quickly establish guidelines and standards for disposable products so they can secure and rely on their disposable products’ supply chains.
Ongoing bottlenecks in downstream processing continue to cause headaches for many biomanufacturers. While several companies have introduced products to ease these bottlenecks, additional work on technologies to improve downstream processing capabilities is warranted. To that end, Madison, WI-based SciLog recently developed a fully automated, single-use purification platform that purportedly improves downstream processing efficiencies and may help cut costs. Other companies are developing disposable format expanded bed adsorption and high capacity monolith and membrane adsorbers to improve capacity during the capture stage in MAb biomanufacturing — an industry that is poised for explosive growth. Major improvements and innovations in disposable downstream technologies are necessary to prevent downstream operations from being “swamped” by vastly improved upstream operational efficiencies and cell culture product yields.
WHAT DOES THE FUTURE HOLD?
While most of the early growth in the single-use market was in disposable storage bags and mixing systems, the use of disposable bioreactors has almost quadrupled since 2005 according a 2009 BioPlan Associates survey. Further, there has been a steady increase in the number of biomanufacturers that are turning to single-use, disposable solutions to cut costs and increase facility turnaround times. Small-to-medium contract manufacturing organizations, especially those specializing in clinical-scale biomanufacturing, are the primary drivers of the single-use market — although the technology has also been well received by large biomanufacturers like Amgen, Genentech, and others. Industry thought leaders and biomanufacturing experts predict the single-use disposable market to continue growing as biopharmaceutical companies increasingly shift their focus to development of high-potency-low-dose niche products in the areas of oncology, therapeutic vaccines, and personalized medicine.
Despite the obvious savings in capital expenditures and labor costs and improved facility operations, it is unlikely that single-use, disposable technologies will entirely supplant or eliminate the use of stainless-steel systems in biomanufacturing. Sartorius’ Gottschalk contends that, “Stainless steel is appropriate when a single product manufacturing facility is responsible for commercial manufacture of a blockbuster drug.” Further, ATMI’s Craig suggests there are certain size limitations and physical constraints that must be considered before determining whether or not single-use, disposable products are appropriate for a biomanufacturing operation. “Bioreactor and storage bags larger than 2,000 L become unwieldy and difficult to manage,” says Craig. “Stainless steel bioreactors may be a better option for biopharmaceuticals that require larger upstream volumes,” he adds.
Finally, Gottschalk suggests that, “No single manufacturing model can fill all products and processes, and there is no value in dogmatically sticking to single-use, disposable or reusable options.” He and others contend that in the near future most biomanufacturing facilities will likely be hybrid operations that contain both stainless steel and single-use, disposable components. Nevertheless, the increasing use of disposable single-use products by biomanufacturers will continue to lower costs, improve operational efficiencies, and most importantly, provide biopharmaceutical companies with more manufacturing options as they attempt to develop and bring new medicines to market.