The bioprocessing industry today is being yanked in two directions, as single-use technologies gain the ascendant, while at the same time there is still a demand for cold, hard steel for large-scale production. In order to gauge their performance, single-use technologies are evaluated on a small scale. Thus scalability is an important consideration, since modeling strategies depend upon their applicability when developing large commercial operations.

Investigators must take cognizance of the construction materials, design of modules and other components, efficiency, and overall cost factors, according to a number of speakers at the recent annual Bioprocessing International conference in Boston.

Protecting Bulk Drug Substance During Cold Chain Handling

Storage, preservation, and transport of bulk drug products demand robust and resilient materials, explained Joe Cintavey, product manager and material science specialist with the PharmBIO division of Gore. Cintavey discussed the use of PTFE (polytetrafluoroethylene), a versatile polymer that has long been the core of the company’s product offerings, and its newest application in the area of bulk transport and storage.

With much of drug development moving into the area of biologics, including vaccines, monoclonal antibodies (mAbs), and antibody drug conjugates (ADCs), keeping temperature-sensitive products stable is essential, as they are often frozen at temperatures from –40°C to –86°C.  At these temperatures, the choice of materials is greatly narrowed because of the tendency of traditional polymer-based materials to become brittle and fragile while frozen. “Breaking and cracking is a major concern when handling a bulk drug which may be valued in the hundreds of thousands of dollars,” said Cintavey.

Elaborating on these statements he continues, “we have developed a single-use container composed of a PTFE composite that can be used to store drug substances at low (–86°C) temperatures while remaining flexible and not becoming brittle.”

PTFE’s use in the STA-PURE™ flexible freeze container makes sense because one of PTFE’s most interesting qualities is its durability when frozen. PTFE is also well known for its high purity, inertness, and biocompatibility.

“Because of the molecular stability of fluoropolymers, like PTFE, used in the construction of these containers, contamination of the product due to leachables and extractables is not a concern as is the case with traditional polymer-based container materials,” added Cintavey.

Although Gore’s PTFE material is endowed with a number of positives as a construction material for low temperature storage containers, it cannot be gamma sterilized, the method of choice in pharmaceutical processing.  “We have found that irradiation is not an option, as it causes unacceptable degradation to the molecular structure of the material,” he stated. Instead, the bags are sterilized with ethylene oxide, an approach commonly used in implantable medical devices.

Ramping Up Single-Use Manufacturing for Commercial Production

The decision to pursue single-use technologies in biologics manufacturing as opposed to multiple use is by its nature complex, but even more so in large pharmas with footprints that cover the planet, as exemplified by Bristol-Myers Squibb (BMS). With operations in many countries, its bioprocessing protocols are under constant updating and revision, as companies scramble to keep ahead of one another. “As we move our molecules into clinical production, we are converting previous hybrid operations to entirely single use,” said Lance Marquardt, associate director for upstream processing at the BMS Hopewell, NJ, facility.

The biologics under scrutiny at the various plants are mAbs, manufactured on a small scale with single-use consumables. These products are noteworthy as they allow decreased turn around time and do not require validation. However, “we had to triple our warehouse storage space,” Marquardt stated, “as moving to full single-use processing required a one month’s supply of single-use consumables.”

With a large number of different molecules, the Hopewell site is geared to handle 10 different projects with up to 4 underway at any one time. There are two separate suites, and the upstream and downstream facilities may simultaneously process different molecules. These turn around activities can be completed in as little as one day in the upstream phase.

The Hopewell facility and the company’s clinical manufacturing facilities in Devens, MA, are now 100% single use with the exception of the downstream purification columns. Another site, in Cruiserath, Ireland, has integrated single use for production up to the 2000-L scale in the seed train and up to 1000-L for media and buffer preparations, with about 30% of all operations done in single-use or disposable systems. The company’s large-scale plants in Devens, MA, and Syracuse, NY, utilize mainly stainless steel, but employ single use and disposables throughout the cell expansion phase to the 25-L scale and up to 200 L for media and buffer preparation.  Less than 20% of all operations at these plants are single use.

Facilities typically have their own site-level management structure. There is a supply planning group that coordinates overall commercial and clinical supplies with internal and external manufacturing capabilities and determines which plant site will be asked to manufacture which product and how much to be produced in a given campaign.

Looking to the future, Marquardt asserted, “We are looking at expanding the implementation of single-use equipment within the BMS manufacturing network; while there are many challenges, we do not see any that are insurmountable as we move forward.”

Lean Principles Applied to Single Use

MilliporeSigma is currently carrying out a major program for improving site design, according to William Faria, head of operations, and Sara Bell, senior marketing manager, both of whom work out of the company’s Danvers, MA, facility. The aim is to advance efficiency and speed the delivery of product.

“We use the ‘lean principles’ approach, a new program for improving the process flow, that uses cultural modification and incorporation of ideas from our teams to make the operations more cost-effective and productive,” said Faria. “We improved our production floor configuration, modeling the space by using cardboard cutouts laid out on the floor, to yield a full-scale picture of traffic flow. Then, with input from our staff operators, we were able to greatly improve the efficiency of the process. The redesign of the workspace resulted in a lead time that was cut in half, and there was a dramatic decrease in customer complaints.”

In addition, the team introduced other updates and modifications, such as “English As a Second Language” instruction. “Since communication and workforce input are a major part of our program, given our international team, we felt a responsibility to optimize the process,” said Bell. “But the main focus of the program is to build a culture of continuous improvement, by encouraging the staff to aim constantly toward improving product quality, producing more, and working more efficiently.”

As a company with an international presence, MilliporeSigma operates facilities all over the world. But while water, utilities, construction costs, and salaries may vary widely, these are not the deciding factors in plant location and design. Strategic fit, customer reach, and availability of talent are the most important part of this decision. But the primary need “is the overall footprint and how it fits into our long-range strategic plan,” states Faria.

Can SUBs and SUMs Be Best Friends with QC Micro and EHS?

“Single-use technology can reduce new manufacturing facility startup timelines since clean-in-place and sterilize-in-place (CIP-SIP) cycles do not have to be developed and become certified,” stated Katherine Leitch, director of technical services at Alexion; she discussed microbiology quality control (QC Micro) guidelines and environmental, health, and safety (EHS) guidelines and their impact on the adoption of single-use bioreactors (SUBs) and single-use mixers (SUMs).

In a wide-ranging discussion, she elaborates on how the properties and constraints of single-use technologies affect planning decisions for ongoing capital project at Alexion’s Athlone, Ireland manufacturing facility. “The implementation of safety aspects that are important to consider with single-use technology are minimizing ergonomic and potential for falls from heights,” she explained. The current Alexion Athlone manufacturing facility capital project utilizing single-use technology has incorporated worker safety considerations early in the project during the user requirement specification (URS) development and subsequent design reviews. The potential employee safety risks are lower with single-use technology since by design there is less interaction with hazardous energy.”

The safety advantages of single-use technology include the reduction of high hazard safety risks to operators. When using single-use technology there is less potential exposure of operators to hazardous energy since there are no CIP cycles, no SIP cycles, and no high processing pressures.

Leitch asserts that an important advantage of SUBs is that any sterile boundary integrity issues are highly visible so there aren’t unknown concerns, as is the case with stainless-steel systems which may be endowed with complex automated valve sequences. Although the potential for bag leaks is a disadvantage, this exigency can be dealt with through adoption of a pre-use pressure test after bag installation.

She adds that SUMs have an advantage over SUBs in that generally bag leaks from a SUM have less potential impact to product quality and batch success than leaks from SUBs.

Leitch also mentions bioburden control and the risk of microbial contamination in single-use technology. The economic impact of batch failure due to a bioburden incident is enormous and could cost a firm billions of dollars in lost revenues and correction of the root causes. A significant advantage of single-use bioreactors is that integrity issues of the sterile boundary are highly visible. From a bioburden control perspective, since there are no reusable product contact surfaces in single-use systems, there are no risks of biofilm development which reduces potential multi-lot product quality risks.

Balancing Options

In choosing between single-use and multi-use solutions, there are a number of factors that need to be reckoned with, as companies seek to develop a set of general principles to govern the selection process. Today, the overriding consideration is the scale of the operation, with decision makers favoring using single-use technology in batches under 1000 L and multi-use solutions for larger quantities. Other factors affecting the decision include the type of product (batch versus continuous), the phase (clinical or research) of the product, reductions in cleaning requirements, capital investment, turnaround time, and risk of product cross-contamination. The weight of these considerations is sure to change in the future, as the technology is changing rapidly, which is sure to influence the decision.

Confronting Viral Production Challenges

Optimization of lentiviral vector production requires a detailed analysis of upstream processing, notes Carol Knevelman, Ph.D., head of process R&D at Oxford BioMedica. She presented her team’s work on the design and application of this technology for use in gene therapy protocols at the Sartorius Stedim Biotech Upstream & Downstream Technology Forum in Goettingen, Germany, earlier this year.

“We have focused on understanding and improving our suspension cell culture production process,” Dr. Knevelman explained. “Our strategy was to employ small-scale systems in order to study the impact of process parameters on vector titer and quality. With the increased number of experiments afforded by this strategy, we were able to employ ‘design of experiment’ approaches in a shorter time frame.”

The Oxford Biomedica team sought to evaluate the engineering characteristics important for successful scale-up and process robustness in order to maximize the chances for success at commercial scale. With this knowledge, the team assessed several commercially available bioreactors and selected a system that met the critical parameters required for the process. “We have been successful in developing a GMP-compliant manufacturing process at 200-L scale,” Dr. Knevelman continued. “And we have recently invested in the automated ambr® 250 high throughput system, which we plan to qualify for future process development and characterization activities.”

Oxford BioMedica’s LentiVector® platform is an advanced lentiviral-based gene delivery system designed to overcome the safety and delivery challenges associated with earlier-generation vectors. The platform was designed so the vector can be modified for a wide range of applications, including selective targeting for gene and cell therapies. The vector has been adapted for CAR-T cancer therapy and has been successfully employed in a long-term Parkinson’s disease project, recently licensed out to Axovant Sciences. Clinical trials utilizing the first candidate product, ProSavin®, have previously demonstrated encouraging clinical benefits in Parkinson’s patients.

Subsequent optimization of the vector system has led to the development of a second-generation vector, AXO-Lenti-PD. The vector delivers three genes that encode key dopamine synthesis enzymes. When injected directly into the brain’s striatum, AXO-Lenti-PD genetically modifies cells to produce dopamine, replacing that which is lost during the course of the disease. If this gene therapy strategy is successful, it will provide long-term benefit for a number of years following a single administration, unlike current drug treatments which lose efficacy with continuous use. “When we began this program a number of years ago, we envisioned a one-shot injection protocol,” noted Dr. Knevelman. “Axovant is now advancing to a trial of the second-generation product. Oxford BioMedica is also developing a LentiVector platform–based treatment of wet age-related macular degeneration which has completed Phase I clinical trials.”

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