The use of single-use components in the biopharmaceutical industry is not new. For more than a decade, a range of disposables have been available and commonly used — plastic film bioprocessing containers, microbial sampling bags, encapsulated filters, sterile connection devices, tubing, flasks, roller bottles and hollow-fiber membrane systems, to name a few. What began as a handful of individual components is now evolving into a category of preassembled, sterilized, and validated integrated disposable systems. The latest innovations to hit the market are 500-L to 2,000-L disposable bioreactors and cryogenic storage bags, further expanding the design space for single-use applications in biopharmaceutical manufacturing processes.

Over time, the biopharmaceutical industry’s level of comfort with single-use options has grown. Sales of disposable bags, containers, and tubing are increasing annually by 10–20%, according to a recent worldwide report surveying 187 biopharmaceutical manufacturers and contract manufacturing organizations (1). As options for innovative single-use technology continue to expand, the attractiveness and feasibility of a fully disposable approach also increases — for certain situations. Although solutions that reduce costs and increase flexibility and speed are key to our industry, the current questions are strategic. When and how are disposables best integrated into a pharmaceutical manufacturing pipeline? The answers are far from simple.

Equipment is expensive for this industry. Any major investment can pose risk in light of uncertainties about whether clinical-trial molecules are efficacious, whether capacity is on target, and whether business models operate according to plan. Disposables offer faster response times and can allow companies to defer or reduce capital costs associated with building large plants for products that are at risk pending clinical-trial outcomes. Yet it’s unclear where disposables are most cost-effective. Procurement and disposal of inventory do incur certain costs, and up-front costs of disposables tend to be higher than for other systems. So a key question that remains to be answered regards when and to what extent to incorporate such components. In addressing this, we at Wyeth have had to look closely and carefully at a wide range of variables.

The Andover, MA, campus of Wyeth Biotech (the organization within Wyeth that is dedicated to development and manufacturing of recombinant-protein biopharmaceuticals and vaccines) is one of the largest biopharmaceutical operations in the United States. Nearly 1,900 scientists, engineers, technicians, and other biopharmaceutical professionals work in a team-based environment there to develop production processes and analytical methods and to manufacture and control product candidates for clinical trials and products for global markets. Wyeth Biotech is home to leading experts in development and commercialization of human pharmaceuticals using recombinant DNA and other technologies. The company has a diversified product pipeline for therapeutics in treatment areas such as anemia, Alzheimer’s disease, hemophilia, cancer, bone damage, inflammatory conditions, and immune system disorders.

WYETH BIOPHARMA (WWW.WYETH.COM)

Over a decade ago, Wyeth Biotech began incorporating single-use technologies into preexisting large-scale manufacturing facilities. We found that the availability of bioprocess containers (BPCs), encapsulated filters, and multisampling devices offered advantages in certain scenarios. The advantages included labor reduction by eliminating vessel set-up as well as clean-in-place (CIP) and steam-in-place (SIP) activities.

For Wyeth Biotech, the initial incursion into BPC use was undertaken for situations in which the components were used in simple but key operations. Processes using pressure vessels of 200 L or smaller for solution storage of media, buffers, and process intermediate collection/storage events were of early interest. Our requirements for BPC technology were basic: A disposable bag had to offer integral storage of solution, and it had to be compatible with process solution chemistries. To ensure connectivity with existing unit operations, we scrutinized closely our selection of filters, tubing sizes, and aseptic connectors. Tube welding and sealing were influential in guiding our tubing selection.

We immediately made operational time-saving efficiencies through some elimination of CIP and SIP activities. The use of BPCs expanded to include larger volume applications (>2,000 L). Ancillary savings were realized when preventative maintenance and calibration of mobile and fixed equipment were eliminated for cases in which BPCs were implemented. Additionally, encapsulated filters and disposable sampling devices offered opportunities for incremental time-saving and labor efficiencies by removing preparatory and cleaning work associated with sample equipment devices, filter housings, and inserts.

Quality Control

At first glance, purchasing a preassembled, sterilized system or using disposable components appears to shift the burden of associated validation from drug manufacturer to single-use supplier. However, the burden of responsibility remains with the biopharmaceutical manufacturer even so. No matter what equipment or components are used in the manufacturing process of a medicinal product, a comprehensive program is required to ensure the safety, identity, strength, quality or purity of that drug.

Increased use of disposables raises questions in uncharted new territory. Consider the potential regulatory and validation issues surrounding the chemistry of extractables and leachables. To establish what chemicals/compounds might be introduced into a process and product as a result of interactions between a pharmaceutical solution and its bioprocess container system, strong solvents are used to extract substances from the contact surfaces to establish an extractables profile. Leachables are chemicals/compounds introduced through the interactions of disposables and actual process solutions. They are generally a subset of the extractables. Just as the question of leachables and their impact on a product is routinely addressed with filtration, it needs to be addressed in terms of disposables. The risk of extractables and leachables from a disposable system must be explored in detail.

For Wyeth Biotech, there are several facets to the qualification of disposables. The first is reviewing a vendor’s validation package. It typically includes information related to materials of construction, USP Class VI, extractables, heavy metals, particulates, pyrogens, and cytotoxicity testing. Vendor studies of leachables and extractables are often based on model solutions that represent worst-case scenarios, necessitating further investigation by end users. We build upon this foundation with process-specific qualifications that include solution chemical stability, microbiological integrity, and process performance studies such as cell culture performance studies using entirely disposable systems. In certain cases, Wyeth partners with vendors to conduct additional extractables and leachables testing using an array of solutions or specific process solution to further support the acceptable use of a single-use technology.

Meeting Market Demand

Manufacturing drugs targeted to “blockbuster” markets requires facilities that can take years to come online, although fewer than one in 10 candidate drugs survive clinical trials. Before an organization has all the information needed to determine whether a drug in clinical trials is viable, a make-
or-buy decision must be made on whether to invest in a large-scale facility. Single-use bioreactors can give companies the flexibility to handle more products and increase capacity more quickly than expansion of a conventional stainless steel facility could. This could increase the economic viability of small-market therapeutics, paving the way toward personalized medicine manufacturing.

Over the past five years, Wyeth has developed a research and development model designed to increase project success rates while reducing project cycle times. Key 2006 elements of this model included advancement of 15 new compounds and two new vaccines into development and entry of 12 new medicines into first-in-human clinical trials. In 2006, Wyeth spent about $3.1 billion on R&D, with an emphasis on pharmaceutical, vaccine, and biopharmaceutical approaches to treating and preventing disease. The company has been able to put as many as six biopharmaceutical candidates into the clinic each year. At any one time, it has up to 10–15 such projects in development for neuroscience, inflammatory disease, cardiovascular and metabolic disorders, oncology, and women’s health.

This company’s large-scale commercial plants speak to high-quantity market demands. Dedicated large-scale bioreactors >1,000–2,000 L in capacity are most likely to remain stainless steel. But when commercial plants are saturated, judicious use of disposables could provide speed and cost-effectiveness without incurring costly renovations or capital investments. Wyeth BioPharma’s clinical manufacturing facility is rarely dedicated for an extended period to any one product candidate. Therefore, approaches that offer advantages for speed of change, elimination of cleaning validation efforts, addressing capacity fluctuations, and flexible fluid movement are very attractive. In many situations, single-use technology offers strategic advantages for clinical manufacturing.

Hybrid Systems and Beyond

Our drug substance clinical manufacturing operations involve a hybrid approach that incorporates disposables in concert with fixed and mobile equipment to offer flexibility, efficiency, and reliability. Integrating disposables into existing facilities this way can increase speed and capacity. For clinical and commercial operations, if the disposable systems work as expected, we can implement them in closer to real time to address our needs for increased capacity until long-term manufacturing needs based on clinical efficacy and market requirements become clear.

WYETH BIOPHARMA (WWW.WYETH.COM)

As single-use technology continues to evolve, disposable cell-cultivation systems offering effective mixing and aeration conditions are becoming available. The first were rocking motion systems that delivered conditions comparable to those achieved in shaker and spinner flask seed-expansion operations. The advantages of such technology included ease of use, elimination of spinner-flask cleaning, and improved cell-culture process performance. Today, our commercial and clinical biotech manufacturing operations incorporate such systems predominately for seed-expansion operations.

Recently, Wyeth BioPharma conducted preliminary characterization and cell-culture performance investigations of larger, more sophisticated disposable bioreactor systems. If mammalian cell culture single-use technology has been around for some time, what has driven our recent interest in it? The answer lies in increased process yields. In the past 20-some years, cell cultivation processes mainly achieved low-to-moderate protein expression yields of about 10 mg/L to 1 g/L. To meet product market demands with such low- to moderate-yield processes, thousands of liters of culture were required.

So a lack of scalability in previous disposable systems for cell culture limited their attractiveness. Because of mixing and aeration limitations, this technology could be scaled up only by increasing the overall number of devices. Resulting operations would grow cumbersome, labor-intensive and costly because of the large number of disposable devices and systems required. An alternative approach involved large stainless-steel bioreactors (2,500–15,000 L) that delivered appropriately controlled conditions (e.g., mixing, aeration, pH, temperature) while providing an economy-of-scale advantage.

Advances in antibody-like protein expression technology have increased yields up to 5–10 g/L, an order of magnitude and greater improvement over years past. Advances in controlled mixing and aeration conditions with disposable bioreactors, along with the significant protein expression technology yield improvements, are allowing companies such as Wyeth BioPharma to consider disposable bioreactor applications as cost-effective options for manufacturing large quantities of proteins.

Our development pilot-production cell culture operations have executed bioprocesses that use disposables alone. From vial thaw through seed expansion into a 500–L disposable production bioreactor, single-use technology proved to be robust and easy to use while providing desired culture performance. Comparisons conducted at Wyeth BioPharma of a disposable 500–L system and 500–L stainless-steel bioreactors showed that these systems performed similarly. With higher cell-culture productivities, material generation from a 500–L disposable line can produce up to 5 kg of material per cell-culture batch.

Currently, our column chromatography, cell separation, and ultrafiltration operations are not unit operations amenable to single-use technology. However, the solution delivery, connectivity, filtration, and in-process pool storage operations all involve single-use technology.

Looking Ahead

It is clear that an increasing array of disposable components offer biopharmaceutical manufacturers opportunities for improved production efficiencies, safety advantages, and plant flexibility. The industry’s needs for consistent, high-yield production that can respond nimbly to changes in clinical prospects, market demand and development cycles, and lowered investment in production infrastructure may be addressed with the aid of single-use systems. But these widely touted advantages must be evaluated in the context of a bigger picture, one that varies from one biopharmaceutical manufacturer to the next.

Use of disposable systems is not a stand-alone concept. It has to be considered along with a long list of variables involved in a complex assessment process. Moving toward a plant with totally disposable bioreactors is far more complex than simply adding a handful of single-use components. Whereas traditional stainless steel systems represent years (sometimes decades) of engineering tweaks and improvements, disposables introduce some new unknowns.

Nevertheless, the use of disposables will continue to expand in the biopharmaceutical industry. Yet as long as single-use systems lack even some of the functionality of stainless-steel technology, they may most often end up filling the needs of niche users. Disposables manufacturers must continue addressing the inevitable limitations in their system capabilities as both industries collaborate to move toward ensuring well-designed, integrated processes for incorporating single-use products into bioprocess manufacturing operations.

REFERENCES

1.) 2005.Third Annual Report and Survey of Biopharmaceutical Manufacturing Capacity and Production, BioPlan Associates, Inc., Rockville.