The Search for Bioprocess Productivity Improvement

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The biopharmaceutical industry has long been working to refine and improve the biomanufacturing process to improve monoclonal antibody (mAb) productivity. Some success has been achieved in upstream bioprocessing where cell titer has been greatly increased as the result of better cell-culture methods and improved bioreactor performance, as well as optimized nutrition in cell-culture media and supplements. Biomanufacturers, however, continue to seek new and improved ways to increase productivity, including innovations in bioprocessing.

Obstacles to mAb production

The biggest challenge in mAb production is improving mAb titer without impacting product quality, and this is dependent on the stability of the cell lines used as the source and the expression systems with which the mAbs are produced. In upstream processing, determining the duration of the cell-culture process, the relative low density of the cells, and/or accumulation of stress-generating byproducts such as lactate or ammonium are also critical challenges.

In addition, there still remains quite of bit of work to be done on the upstream side to increase yields, including work needed to fully characterize all the materials going into upstream processes. Currently, three grams of API per liter is traditional for mAbs, but some biomanufacturers are claiming higher concentrations at 10 g/L and up to 50 g/L, which, from a scale-up perspective, sounds aggressive, notes Claudia Berrón, vice-president of global commercial development, biopharma, at Avantor, a manufacturer and distributor of products, services, and solutions to the life-sciences and advanced technologies industries.

Depending on their characteristics, each raw material can react differently with the drug molecule, and many raw materials going into upstream cell-culture processes have not been fully characterized or optimized for the target molecule, Berrón explains. Thus, upstream optimization needs better characterization of all media components, and, more specifically, anything going into the cell-culture supplement with that particular molecule is crucial as people seek higher upstream productivity.

Improving productivity has largely been a question of progress in three areas, adds Nigel Darby, advisor to the CEO, GE Healthcare Life Sciences. First, mAbs were expressed at low levels in early bioprocessing in the early 1990s, typically 10- to 20-fold lower product titers than today, which necessitated the use of large bioreactors to manufacture sufficient product quantities. Second, downstream purification was limited by chromatography resins with four to five-fold lower capacity than today, particularly in the Protein A capture step, which necessitated the use of large volumes of resin to bind the product and wide-diameter chromatography columns to cope with the large volumes of dilute, clarified cell-culture supernatant coming out of the process. Third, both aspects of low productivity required big complex factories to manufacture significant quantities of mAb, which required high capital investments, long construction times, and significant financial risks if products failed in clinical trials, Darby explains.

To tackle these challenges, technology has fortunately been rapidly evolving to provide solutions. In the past 10 years, significant improvements in cell culture titers have been achieved, with 5–10 g/L being achieved and around five-fold improvement in Protein A resin capacity, Darby asserts. “The net effect of these improvements has considerable impact. Bioreactors have shrunk from 20,000-L volume to 2000 L, and two-meter chromatography columns are replaced with 50–80-cm columns … all to achieve the same production output,” he states.

In addition, single-use technology is beginning to replace the fixed stainless-steel facility designs that were once prevalent, particularly large stainless-steel bioreactors are being replaced with much smaller single-use bioreactors. Today, the most advanced biomanufacturing facilities are running with smaller unit operations and reduced infrastructure because of single-use technology, which is driving significant reduction in capital investment and construction times. Furthermore, the financial risk profile is much more favorable with scaled-down, right-sized facilities using single-use technology, according to Darby.

Engineer fixes

To meet the challenges faced today and efforts to improve mAb productivity, design and development engineers are employing several methods or approaches to resolve these issues. For example, at Agenus Inc., the company’s design engineers and scientists look into ways of developing efficient and high expressing vectors for cloning cell lines and sometimes may be sub-cloning for optimization. The company now has cell lines with excellent growth rates and high specific productivity for both fed-batch and perfusion cultures for several immunoglobulin G (IgG) isotypes, says Al Dadson, head of Global Biologics Manufacturing, Agenus, an immuno-oncology company specializing in antibodies, vaccines, cell therapies, and adjuvants for treating cancers.

“Our development engineers and scientists are working on both upstream, downstream, and analytical/formulation development platform processes to increase aspects of robustness, scalability, and reproducibility to complement high expression systems to reduce COGS [cost of goods sold],” Dadson says.

Meanwhile, at Avantor, the company has been focusing on dramatically improving materials characterization for upstream processing. The company is specifically working directly with mAb producers to find the right combination of cell-culture components to optimize upstream yields and has recently implemented new laboratories, one focused on mammalian upstream cell culture and another focused on microbial fermentation, at its facility in Bridgewater, NJ, according to Berrón.

In downstream bioprocessing, Avantor has process engineers working on optimizing three parameters: yield, process time, and purity. “Depending on the target protein molecule and other factors, we can optimize various parameters such as resin chemistry, buffer type, and specific additives that can modulate separation performance to get higher yield or higher purity, or we can reduce the number of process chromatography steps. In addition, we can optimize buffer conditions and flow rate through the columns to decrease processing time,” says Dr. Nandu Deorkar, vice-president of research and development, Avantor.

“One area where we are having success is more targeted ligands. Certain feedstock may contain closely related product impurities that may require multiple traditional chromatographic steps. It is a common challenge we see in recombinant protein, beyond traditional mAbs,” Deorkar further states. “To address this challenge, we have been engineering mixed-mode, multimode, and hydrophobic chromatography resins that help optimize the removal of these closely-related impurities. This method has mainly been applicable to any recombinant protein that is produced in a microbial fermentation process,” he adds.

Process engineers and scientists are also developing refined processes, such as implementation of perfusion steps, adds Melanie Diefenbacher, PhD, scientific consultant, Genedata, a data intelligence company that offers an integrated enterprise workflow platform to streamline R&D workflows and improve productivity. To achieve this refinement, they try to take a broader, integrated view on the overall process from the development of the manufacturing cell line up to the downstream and formulation steps. Process engineers and scientists are also using miniaturized, automated approaches to study factors influencing manufacturing success. “Therefore, digitalization methods, such as artificial intelligence and deep learning, are becoming increasingly important to support these efforts,” Diefenbacher says. “Using cyber-physical systems, the Internet of things, and cognitive computing, supported by smart laboratories and integrated and scalable information technology (IT) systems, R&D operations, and manufacturing systems are becoming decentralized, and at the same time intelligent, flexible, and highly integrated.”

Bioprocess innovation advancement

For the most part, the biopharmaceutical industry still has some challenges with assimilating the advances made in recent years to improve mAb productivity. There remain many operations that have not yet started to use the best technologies that are available today, according to Darby. “Given the lifecycles of many processes, it can be difficult to assimilate new technology quickly because of the constraints of regulation and cost as well as risk of change,” he says.

Darby points out, though, that progress in technology continues, nonetheless. “For example, in the challenging downstream area, we are moving to consider new higher productivity technologies in purification, such as the use of nanofiber products as an alternative to chromatography beads. On the other hand, there are things we can do better with the resources we have today, [such as] better use of manufacturing process and raw material data to optimize manufacturing output and quality.”

Compared to other industries, biopharmaceuticals are at a relatively early stage, but given the complexity of biomanufacturing, there are likely rapid gains to be made simply by understanding, for example, the effects of raw material variation on productivity and better understanding of how to control and predict that, Darby asserts.

Another area for potential bioprocessing productivity improvements is in downstream processing, where single-use technology can be combined with process chromatography columns, says Deorkar. “Using single-use systems has the potential to move from a batch-based approach to something approaching a connected continuous process. It will be possible to minimize the large storage tanks and use single-use systems to streamline how you collect the samples, how you load the samples, and so forth. There are single-use systems that make it much more of a continuous process and remove the time required to clean, dry, qualify, and validate sampling and storage systems between chromatographic steps,” he states.

Single-use systems have the potential to improve productivity across the entire mAb production process, especially in terms of sampling, adds Berrón. “Drug producers have to sample for quality and process control purposes many, many times continuously. Typically, to effectively sample, you sample more than what is needed, and, in some cases, it isn’t possible to sample exactly what is needed.”

The industry is using approaches like perfusion or some sort of continuous manufacturing to increase volumetric output and increase yield, in addition to developing high-producing cell lines, confirms Dadson. “Systems like the ATF [alternating tangential flow] and other tangential flow systems have been known to increase productivity by several fold. The use of PAT [process analytical technology] in platform facilities is another avenue being explored by industry,” he says.

Dadson also notes that certain approaches in cell-line engineering are using Chinese hamster ovary (CHO), nonsecreting null (NS0), Sp2/0, HEK293, and PER.C6 cell lines as host systems, although more than 70% of industry today is using CHO cells. New approaches also include transgenic plant and animal systems for host cells.

The Agenus West team in Berkeley, CA, for example, is working with Agenus’ cell line-development team in Cambridge, UK, and its Discovery/R&D teams in Lexington, MA, to ensure cell lines are developed with the required product quality attributes and commercial manufacturability. “The availability of desired cell lines for commercial production shortens manufacturing time for drug development. Coupled with this fully integrated approach, Agenus West thrives on the latest cutting-edge technology platforms in-house, making us self-reliant and giving us the advantage of manufacturing speed, cost efficiency, operational flexibility, and manufacturing technology transfer to commercial scale partners-all with desired product quality,” Dadson states.

Approaches to improving mAb productivity have included increasing throughput and reducing cycle times using new automation equipment, says Diefenbacher. Another approach involves using new and refined bioprocesses that include the application of fully or at least partially continuous processes, such as upstream perfusion process steps. “In terms of newer innovation, the biggest push right now in productivity improvement is expected to come from the digitalization of the biopharma industry, which will improve process robustness and product quality and result in a more efficient use of resources,” Diefenbacher states.

Future mAb enhancement

Future mAb production facilities are expected to see the implementation of a broad range of technologies, including the use of nanofiber technology in place of chromatography beads, increased automation and digitization of processes, and single-use systems. A few facilities are already exploring the use of some of these technologies today with many new facilities under construction, Darby observes. Meanwhile, innovations such as the nanofiber technology are still in development.

“The smaller highly flexible facility with a high content of single-use technology seems to be the future for much of the industry. Instead of scaling up, many now talk of scaling-out-building capacity as needed by rapid construction of new small-scale facilities rather than taking the risk to build a single large facility,” Darby says.

As the mAb production process continues to intensify, the lack of “downtime” that used to occur naturally as a consequence of the greater demands of cleaning and maintenance in standard infrastructure puts ever more pressure on manufacturing teams and extended supply chains to become more efficient, Darby also points out.

“The burden of some activities will be transferred to suppliers, as we see with the implementation of single-use technology, and this is expected to increase. We are still undergoing a significant transition in implementation of single-use technology with more operator training required to ensure these technologies can be applied successfully, particularly as productivity increases,” he states.

“Right now, the biggest push is expected to come from the digitalization of the biopharma industry, which will improve process robustness and product quality and result in more efficient use of resources,” Diefenbacher adds, noting that most big pharmaceutical companies today are already looking for ways to directly capture the huge amounts of data produced in R&D and manufacturing, such as cell-line selection, process optimization, or media development.

“The implementation of a central data backbone for sharing all data and driving digitalization across all development groups to connect information from upstream, downstream, formulation, and analytics development units is essential for every biopharma organization,” she says.

“We think there will be more use of single-use technology, although there will still be plenty of need for stainless-steel, fixed production systems,” Berrón interjects. Blockbuster drugs would still need stainless-steel production systems, she explains, because they have long production runs, and using stainless-steel is the most efficient way to produce a blockbuster drug. For faster change and faster turnarounds where smaller-volume drugs are involved, single-use technology continuously gains ground in this space.

“We also see greater investment and greater use of advanced data tools, and this is something that Avantor is making significant investments in-digital tools for process optimization,” adds Deorkar. Compared to other industries, even small molecule, the biopharmaceutical industry is lagging in terms of how data is captured, what kind of data is captured, and how it is mined and used productively, he says.

There is also a push for future bioprocess facilities to build efficient continuous processing facilities, Dadson states. The push for facilities that use high-expression cell lines in combination with end-to-end single-use systems to build smaller, cost-effective footprint facilities versus conventional stainless-steel facilities has become an industry focus. “One drawback is the maximum size of single-use systems (2 kL–3 kL) to handle high product demand, especially in oncology, versus >20 kL stainless-steel facilities,” he says.

Finally, the increase in automation to replace low-value activities, such as buffer management, and an increase in real-time data analytics in the management of processes will also require whole new skill sets in the workforce, Darby points out. “Time pressures will likely drive towards more analytical work being performed at or on-line during manufacturing, with paperless workflows. These innovations are just emerging in the most advanced operations but will require changing approaches from plant operators.”

Article Details 

Pharmaceutical Technology
Vol. 43, No. 5
May 2019
Pages: 16–22

Citation 

When referring to this article, please cite it as F. Mirasol, “The Search for Bioprocess Productivity Improvement,” Pharmaceutical Technology 43 (5) 2019.