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New techniques—including single-use technology and continuous processing—simplify the production and improve the products
The term bioprocessing covers a lot of ground. If something uses living cells or something from them—say, an enzyme—to make something else, like a medicine, that’s a bioprocess.
Much bioprocessing work revolves around medicine. When asked if there are any interesting new applications of bioprocessing, Eva Lindskog, marketing solutions leader for life sciences at GE Healthcare in Amersham, U.K., replied, “There is an increased focus on targeted therapies with better efficacy for smaller patient populations.” These approaches include cell therapies, gene therapies and bioconjugate therapies.
“In cell therapy,” Lindskog explains, “cells can be extracted from one patient and expanded in vitro before infusion in the same patient—autologous therapy—or in other patients—allogeneic therapy.” In gene therapy, a patient receives specific DNA to change expression levels of proteins that act like a medicine. “Bioconjugates,” says Lindskog, “are a therapy class where one biomolecule is coupled with, for example, a toxin, an antibiotic or another biomolecule.” She adds, “The combination can make the final drug both highly efficacious and very specific.”
All of this requires bioprocessing, and many other applications exist.
Feeding the process
The goal in bioprocessing is to consistently get the best product yield or titer with the highest product quality. To do this, process scientists analyze variables to fit the best profile possible, such as the effects of glycosylation—for example, protein folding, solubility, enzymatic activity, etcetera—during cell culture. “In many cases, additives tend to provide a partial modulation of glycans, making it difficult to target the desired glycan profile and get predictable results,” says Mark Stramaglia, associate director of technical leadership at Thermo Fisher. “Thermo Fisher Scientific has developed their most advanced feeds, Gibco GlycanTune+ Total Feed and Gibco EfficientFeed+ Supplements, to make it easy to get the desired glycan profile reliably. A transition methodology between them provides a more predictive modulation of forms desired, ensuring product quality.”
Eric Nalbach, associate director of product management at Thermo Fisher, says, “Both feeds take advantage of the Gibco AGT [Advanced Granulation Technology] dry format, further increasing reliability by reducing overall process steps and risks through super concentrations—up to 3×—and auto-adjusting pH and osmality.” He adds, “Once reconstituted, these feeds can be stored at room temperature within the bioreactor suite for 30 days.”
Building better bioprocessing
GE Healthcare’s Xcellerex stirred-tank bioreactors can be used in single-use approaches to bioprocessing. (Image courtesy of GE Healthcare.)“Single-use technology and technologies that enable continuous manufacturing are two current trends,” says Lindskog. With single-use technology (SUT), bioprocessing takes place in a plastic container that is disposed of after the process. “Compared with traditional stainless steel or glass [which can be reused], single use increases the flexibility of the process, minimizes the cleaning requirements and simplifies facility design,” Lindskog explains.
For single-use approaches, scientists can use GE Healthcare’s Xcellerex stirred-tank bioreactors and the ÄKTA ready chromatography system for purification.
With continuous processing—increasing the production cycle from 7–21 to 45–60 days—less time is lost between batches, which increases productivity. “Continuous manufacturing can also be used, for example, [to maintain] the same productivity at a smaller-scale operation,” Lindskog says. “Technologies that enable continuous manufacturing include hollow-fiber filters used with bioreactors in production, and the ÄKTA pcc continuous purification system.”
To expand SUT, says Lindskog, companies must be confident of an ongoing supply of high-quality components, noting that manufacturing could stop if the supply chain doesn’t work properly. “The quality is essential because many single-use products are in direct contact with the pharmaceutical ingredient,” she says, so nothing harmful can leak from the components to the product.
Switching to continuous flow, Lindskog says, is “not always straightforward,” because “additional instrumentation is required, demands on process robustness are increased and the logistics to ensure a continuous flow of material through the facility become more complex.” Still, continuous operation is being used more.
The challenge cluster
The combination of SUT and continuous processing creates many challenges. “One is the fitness of SUT equipment and consumables for continuous bioprocess manufacturing—for us, upstream operations are the primary area of concern,” says Donald Young, senior global product manager for single-use technology at Thermo Fisher Scientific’s bioproduction division.
The SUT materials must fit the application. “Material compatibility of the SUT products used during cell-proliferation operations have become a great concern of our customers, from a risk-avoidance and risk-aversion perspective,” Young explains. “The ideal situation is a fluid contact material that does not alter or impact the contents of the bioprocess liquid held within the SUT product.” Still, a customer must prove “that the SUT products do not alter or otherwise impact their bioprocess liquids,” Young says, and the supplier of the SUT products and the customer must work together to provide the needed testing data.
Consequently, vendors must provide tools for testing. “Standardized tests are available for biological compatibility, as well as mechanical, physical and physicochemical characterizations,” Young says, “but the testing of highest concern is compatibility of the fluid contact material in worst-case situations—extractables testing—and in ‘as-used’ situations—leachables testing.” To do that properly, customers need consistent tests.
As Young explains, “A new extractables testing standard has emerged from a consortium of end-users called the BioPhorum Operations Group, or BPOG.” He adds, “BPOG has proposed an extractables testing protocol that redefines worst-case testing, and provides testing requirements for the individual components that make up single-use technology products, providing the ability for end-users to make side-by-side comparisons between different components and comparable SUT products sold by different suppliers.”
Improved isolation
FibroSelect technology captures specific analytes from bioprocessing with ligands attached to the product’s nanofibers. (Image courtesy of Puridify.)Getting the right components from bioprocessing often requires some form of separation, such as chromatography. Puridify in Stevenage, U.K., developed FibroSelect for efficient isolations of specific components. CEO Oliver Hardick says, “FibroSelect is a solid 3-D matrix structure of cellulosic nanofibers.”
This technology, he says, “delivers a 50-fold purification productivity improvement while maintaining the product-critical quality attributes required for drug safety and efficacy.”
This technology captures specific analytes targeted by the ligands on FibroSelect. “Most notably,” Hardick says, “we use an industry-standard Protein A ligand to select for monoclonal antibodies and similar therapeutic molecules. FibroSelect presents the Protein A ligand on a surface, which enables processors to use the ligand much more effectively and carry out the unit operation in a much faster and more flexible manner.”
This technology improves throughput. As Hardick says, “The drug manufacturer can choose to make single-use operation economically feasible by reducing the unit process size so that the chromatography cartridge’s lifetime—in terms of cycles—can be exhausted over a single batch, or trade that off with running their unit operation significantly faster.”
All steps in bioprocessing medicines must be carefully engineered and monitored. Any modification to the protein being produced—such as adding a carbohydrate, or glycosylation—can impact safety and efficacy. As one group of scientists wrote: “Many factors shape the glycosylation of biotherapeutics, ranging from expression systems and cell culture processes to downstream purification strategies,” and they concluded that “an integrated approach is required to harness glycosylation for the production of optimal and consistent glycoprotein-based therapeutic drugs.”1
To manufacture the best biologically based products, scientists and engineers need tools that allow the finest control, and making the processes as efficient depends on evolv- ing techniques.
Reference
- Zhang, P.; Woen, S. et al. Challenges of glycosylation analysis and control: an integrated approach to producing optimal and consistent therapeutic drugs. Drug Discov. Today 2016; doi:10.1016/j.drudis.2016.01.006.
Mike May is a freelance writer and editor living in Florida. He can be reached at [email protected].