January 15, 2018 (Vol. 38, No. 2)
Vaccine Manufacturing Moves toward Mass Customization
Pathogens evolve and epitopes shift at an alarming rate, threatening to outpace the vaccine industry, which struggles to keep up, even though it has already started to upgrade its manufacturing technology. The vaccine industry needs to consolidate diverse technological advances if it is to truly hit its stride and respond to fast-emerging dangers such as Ebola and Zika.
Fortunately, speed-enhancing technologies are available, and they may be implemented up and down the vaccine production line.
Vaccine manufacturers that recognize the “need for speed” are:
- Elaborating on core molecules to build vaccines of different types, allowing the use of simplified manufacturing platforms.
- Deploying diverse vectors, transfection systems, and host cells to develop highly productive expression platforms.
- Using vaccine-like particles (VLPs) to support plug-and-play antigen-presentation platforms.
- Switching to single-use technologies to reduce downtime between batches, even if the batches consist of different products.
- Incorporating prefabricated and modular units to reconfigure or expand production facilities.
All these developments have a common theme: the streamlining of operations that might otherwise become unwieldy because vaccines need to incorporate more—and more varied—biomolecules. Although higher molecular diversity increases vaccine production complexity, such diversity can be managed.
The management of diversity will be discussed by the vaccine industry’s leaders at the next World Vaccine Congress, which will take place April 3–5, 2018 in Washington, DC. Whether they are slated to present papers or run exhibits on the show floor, these vaccine development and manufacturing experts are prepared to discuss the current state of the industry and its innovation-driven future. For a preview of the insights these experts intend to share, continue reading this GEN article.
Transfection Gets a Jolt
According to James Brady, Ph.D., vice president, Technical Applications and Customer Support, MaxCyte, flow electroporation technology can transfect up to 2 × 1011 cells in less than 30 minutes, obviating the time-consuming and labor-intensive steps associated with making producer cell lines. A wide range of vaccine formats can be produced in multiple adherent and suspension-adapted cell lines.
Flow electroporation is scalable (from 0.5 × 106 to 2 × 1011 cells per transfection run); has high transfection efficiency with multiple cell lines and loading agents; and is compatible with a wide range of culture formats and production systems. The system is cGMP compliant and supported by an FDA device master file.
As with all transient expression methodologies, sufficient quantities of loading agent—typically plasmid DNA or messenger RNA, specific to individual vaccine formats—must be prepared. Many commercial vendors supply loading agents at the scales and specifications required for GMP production. In addition, multiple technologies are available to address the large-scale cell-processing challenges, which are not unique to flow electroporation.
MaxCyte’s flow electroporation technology has been validated for a wide range of cell-engineering applications. It is being used to manufacture commercial cell therapy products, as well as to develop viral-vector and VLP vaccine candidates. The latter applications are being pursued by several commercial and governmental entities.
Single-Use Solutions in Manufacturing
In the past big, bulky, inflexible stainless-steel bioreactors with companion stainless-steel connections were used. Each component required washing, sanitizing, and qualification before use for a new batch or product. This costly endeavor involved considerable effort and time, and contamination was always a possibility.
“Nowadays, specialized bags go into the bioreactors and the connections are plastic tubing; everything is single use, reducing human error and contamination, upfront capital investment, and water usage,” says Daria Donati, Ph.D., director of business development and innovation, Enterprise Solutions, GE Healthcare Life Sciences. “Single-use solutions in manufacturing make it simpler to pass from one product or one batch to another.”
Single-use technologies are integral to GE Healthcare’s FlexFactory systems (Figure 1). “These manufacturing platforms can be deployed—assembled, validated, and qualified—in less than one year where needed,” says Dr. Donati. “Plus, our KUBio turnkey modular facilities reduce the time and risk needed to build facilities. KUBio facilities are available for monoclonal antibody production and are currently being developed for vaccine production.”
KUBio facilities include everything that is needed—from the facility itself to the process equipment for biopharmaceutical manufacture—and they can be delivered in less than half the time it takes to build a typical facility. On-site modular facilities can be assembled rapidly, within eight days of arrival at the site.
A Fast Trak team provides the customer with specific training on production and troubleshooting. This bridging service can also produce clinical material for toxicology studies, as well as for Phase I and Phase II trials, while the factory is being set-up. In addition, the analytical platform, Biacore surface plasmon resonance (SPR) technology (GE Healthcare), supports quality, toxicity, and potency testing. It can be used in both vaccine and biomolecule research and manufacture.
Insect Cell Platforms
ExpreS2ion Biotechnologies has developed ExpreS2, a nonviral, insect cell–based, protein-expression platform. ExpreS2 can produce complex proteins at very high yields and quality with uniformity of glycosylation and excellent protein folding. The platform consists of Drosophila melanogaster S2 cells, expression vectors for stable integration into the genome, and transfection reagent, enabling rapid production of recombinant proteins for in vitro and in vivo use, with a typical timeline of 3–4 weeks from DNA to purified protein (Figure 2).
S2 cells proliferate in suspension, reaching densities of 30–350 million cells/mL in shake flasks. Also, these cells are compatible with batch, fed-batch, and perfusion production modes. Frozen recombinant cells recover quickly, for on-demand, reproducible production of proteins within one week from thawing the cells.
“The ExpreS2 platform has been used in the production of more than 250 different proteins, even in cases where other expression systems have failed,” says Teit Max Moscote Soegaard, Ph.D., director of process development, Expres2ion Biotechnologies.
“Products have been approved by regulatory authorities in Europe and the United States, and some are currently running in Phase I/IIa trials, including two malaria vaccine candidates—a pregnancy-associated malaria vaccine developed by Copenhagen University, and a blood-stage vaccine developed by Oxford University.”
Unlike the lytic baculovirus expression vector systems (BEVs), the ExpreS2 platform relies on virus-free transfection and genomic integration followed by selection of stable polyclonal pools, or a monoclonal cell line. The protein of interest is secreted to the cell supernatant. Product secretion simplifies product harvesting and purification, and for VLP production, it has no baculovirus contamination. Secretion of fully processed viral glycoproteins in other systems (such as CHO systems) often requires overexpression of Furin protease to achieve the same level of homogeneity.
This provides batch-to-batch reproducibility and cultivation options, such as perfusion systems for high yield/reduced cost. Cell and process robustness facilitates the transfer to GMP facilities for manufacturing, decreases process transfer time, and lowers the risk of batch failure/rejection. Lytic systems, such as BEVs, have significant issues with proteolysis of the protein of interest, as well as instability of the viral stock over time.
ExpreS2ion and NextGen, a spin-out from the University of Copenhagen, recently formed AdaptVac, a joint venture company focused on expediting the development of plug-and-play vaccines. AdaptVac says that it utilizes the split-protein conjugation system to generate stable isopeptide-bound antigen-VLP complexes by simply mixing of the antigen and VLP components. That is, simple click-on chemistry is used to display antigens on the surface of generic VLPs.
Compared with single-antigen presentation, the multiple presentation of the antigen on this VLP platform, which in itself is highly immunogenic, elicits stronger and longer-lasting immune responses than traditional subunit vaccines. This provides the ability to efficiently break self-tolerance, which is required for targeting human tumor suppressor proteins. A recent paper1 presents very promising data constituting proof-of-concept-in-animals of a vaccine candidate for HER2-positive breast cancer in an advanced humanized mouse model of breast cancer.
1. A. Palladini et al. “Virus-Like Particle Display of HER2 Induces Potent Anti-Cancer Responses,” OncoImmunology (November 29, 2017), doi:10.1080/2162402X.2017.1408749.