New Analytical Tools Can Reduce Response Times and Increase Capacity for Manufacturing Vaccines

By Barry Buckland, Ruben G. Carbonelle, Christopher J. Roberts, and Kelvin H. Lee

The unique beneficial role that vaccines play in improving human health globally is well established. The World Health Organization (WHO) estimates that 2 to 3 million lives are saved each year by the use of vaccines. In a little less than 30 years, from 1990 to 2018, the number of deaths per 1,000 live births for children less than 5 years old dropped from 93 to 39, a nearly 58% decrease. There are now 25 different licensed vaccines being used worldwide to prevent and control a concomitant number of infectious diseases, greatly increasing the impact of vaccines on the economic and social well-being of mankind.

The most important components of any vaccine are the antigens that can induce an immune response in the patient to confer protection against the disease. The antigen can consist of surface proteins of viruses or bacteria causing the disease, as well as glycoproteins, polysaccharides, and other toxins produced by these microorganisms. The antigens illicit an immune response by activating B Cells that make antibodies or T Cells that can fight pathogens that reside inside cells, such as viruses. The B and T Cells become memory immune cells that are reactivated upon future exposure to the disease.

Early vaccines were based on killed or attenuated virus or bacteria. The evolution over time has been toward the purified antigen and very recently, in the case of proteins, to the RNA or DNA that codes for the antigen. Live attenuated viral vaccines, killed virus vaccines, viral-like particles and protein-polysaccharide conjugate vaccines are all effective and currently in use, but it can take years to develop and deploy these modalities to treat new diseases. SARS-CoV-2 provided a poignant recent challenge, as a virus with the capability of very rapidly infecting many millions of people throughout the world with more than 128 million confirmed cases by March 31, 2021 (about a year after the WHO declared a global pandemic). Such developments clarified the need for new, more rapid, approaches to vaccine deployment.

Vaccine manufacturers turned to technologies that have been in development for several years for gene therapy that rely on the insertion of nucleic acids (DNA, RNA) into a patient’s cells to treat or prevent disease. In that context, once a new viral or bacterial pathogen is identified (for SARS-CoV-2 or more generally), proteomic and genomic tools can be applied to rapidly determine the amino acid sequences of the surface proteins on the microorganism, as well as its complete genetic makeup. With this information, it is possible to determine the genes in the viral vector that are responsible for producing specific proteins on the surface of the virus or bacteria. This enables the possibility of inserting these genes into the patient to illicit an immune response to develop safe and effective vaccines.

“The first licensed vaccine based on this approach was against Ebola, introduced in 2019. This approach involved the use of a recombinant live attenuated vesicular stomatitis virus (rVSV), where the viral vector contains a gene from the Ebola virus glycoprotein that replaces that of the native VSV glycoprotein. When introduced into the body, the virus infects the patient’s cells, which then produce the Ebola glycoprotein to induce the necessary immune response. The development of the Ebola vaccine was one of the most accelerated of any vaccine to that point in time.

Vaccines effective against COVID-19

Recognizing the need for a rapid response to the COVID-19 epidemic, manufacturers deployed vaccines based on delivery of RNA or DNA. The approach followed by the Pfizer-BioNTech and Moderna vaccines involves packaging the messenger RNA (mRNA) required to make the surface spike glycoprotein on the COVID-19 virus into nanoscale phospholipid vesicles that are then injected into the patient. The mRNA provides the protein-building instructions for the genetic machinery of the cells to produce the spike protein. The vesicles protect the mRNA molecules from degradation in vitro and in vivo, and can help to target delivery of the mRNA to the person’s cells. The mRNA is destroyed by the cells once the message is read and the protein production begins.

A second approach, pursued separately by Johnson & Johnson/ Janssen and AstraZeneca/Oxford University, utilizes a modified Adenovirus as a viral vector that cannot replicate in the person, but the vector contains the DNA encoding the gene to produce the spike protein. In this case, the vector essentially infects the person’s cells and introduces the gene for the spike protein into the cell so that it can produce the antigen and generate the immune response.

These mRNA and DNA-based vaccines have opened up many exciting possibilities for fast responses to a wide variety of infectious diseases, and they are sure to play a key role in the future as the world faces new pandemic challenges. However, because they are new, there is much to learn about the clinical response of individuals to these types of treatments, and how to manufacture these vaccines such that they are potent, effective, efficient, safe, affordable and accessible to the world’s population. Improvements are needed in a number of areas for these vaccines, including: how they are manufactured and key quality attributes for the final product; their storage stability and how that relates to product formulation; the expansion of supply chains for assuring high quality raw materials for manufacturing, such as proteolytic enzymes; adjuvants and excipients, including the components of delivery vehicles (e.g., lipid nanoparticles); and the development of new approaches for testing product potency and quality. Tse et al., provide a thorough study of the current status and future of vaccines against emerging coronaviruses, and advocate for the development of “plug and play” platform technologies that enable rapid deployment of vaccines in the future.

The success of the industry in moving quickly from identification of virus targets to providing vaccines across multiple vaccine platforms, and taking significant development risks while leveraging government support, is an excellent example of the power of public- private partnerships in advancing biopharmaceutical development. These relationships can be transformative for global health, but it is not simple to quickly change the biopharmaceutical ecosystem that spans from the supply chain, to companies that develop new medicines, to contract manufacturers for broader product supply, to regulatory agencies and local governments for product approvals and distribution. There remain many risks and challenges to be navigated for innovators of new medicines, particularly those as complex as vaccines and related biopharmaceuticals and medical countermeasures.

The impressive pace at which new vaccines were developed in 2020, tested in clinical trials, and produced for distribution is based, at least in part, on compressed timelines and emergency authorizations by health authorities. Many of the early vaccine candidates for COVID-19 will need to evolve into second generation versions to address new COVID-19 variants or families of variants, and to incorporate improved processes and formulations for greater stability and accessibility. All of these activities may need to be done with the pressure of even shorter timelines, as we know by analogy with perennial examples from seasonal influenza.

Improving manufacturing capacity for COVID-19 vaccines

Regardless of the platform, the timeline for vaccine manufacturing includes several weeks after all the process steps are complete to run batch release assays, and there is great interest by all vaccine manufacturers to reduce this time.

Some of the traditional assays required to release a batch of vaccine are standard and generally used, but may be so time consuming that they significantly delay availability of the manufactured drug product (e.g., due to required sterility testing or adventitious agent testing). Second and third generations of the recently developed vaccines may involve the same vaccine platform, but may also require manufacturing changes that could result in unintended changes in the efficacy or safety of the final product. Examples include increasing the scale of manufacturing, moving to a different manufacturing site, introducing a process improvement, changing the product formulation, or a change in a critical release assay.

A Clinical Bridging Study may be run to reassure the Regulatory Authorities (RA) and the manufacturer that no change in efficacy or safety has occurred, but these studies are very time consuming and expensive. If possible, it is far better to use detailed product characterization assays as a basis for reassurance that the desired change can be implemented in routine GMP manufacturing, with validated methods, and also provide stability data.

A key difference between vaccines and therapeutic proteins is the goal of achieving a strong immune response in patients. As a result, the analytical techniques and the complexity of the data analysis for vaccines can differ significantly from those used for therapeutic proteins. In addition, vaccines are a prophylactic rather than a treatment after the patient is diagnosed with a disease. This treatment of generally healthy individuals requires rapid scale-up/ out of manufacturing during pandemic and seasonal responses, with more difficult projections of yearly patient need compared to other therapeutics.

Advances in molecular and cell biology, biochemistry, and analytical sciences have made possible a new era in which vaccine products can be better characterized with analytical methods. Major improvements in instruments and robotics, and in handling huge amounts of data, enable rapid generation, analysis and secure transfer of information. An ecosystem-wide center focused on analytical, potency, and related assays (i.e., a Vaccine Analytics and Assays Center) that brings together the best scientists in academia and government (e.g., NIST, NIH, CDC and FDA), vaccine developers, vendors and suppliers, and original equipment manufacturers (OEMs) can play a key role in manufacturing high quality, safe and potent vaccines, and foster a shared understanding of analytical capabilities and therefore enable rapid responses to future pandemics. Such a center could result in major advances in several important assays:

• Rapid adventitious agent testing of vaccine batches by next- generation sequencing (NGS)
• Characterization of lipid nanoparticles (LNP) for mRNA vaccines and gene therapies
• Potency assays for mRNA vaccines and how to define a dose
• Rapid cell-based assays for any virus or viral vector and how to define a dose
• Improved potency assays to replace single radial immunodiffusion SRID assays for Influenza
• Quantification of full versus empty virus and between infectious and non-infectious virus
• Rapid sterility tests for batch release testing
• Rapid identity tests
• Characterization of adjuvants
• Characterization of virus-like particles (VLP) by size and shape

In the rapid response to COVID-19, companies have started up multiple manufacturing sites in parallel at increasing scales of operation. Sophisticated analytical comparability is needed to ensure quality from each location and such a center could help enable those studies.

Global human health would also benefit from the development of more temperature-stable formulations and development of these approaches requires meaningful stability assays that can preferably be run in a high throughput manner. There is a significant effort in the development of new formulations for LNPs to increase stability and efficacy of mRNA therapeutics, and the potential for continuous production of liposomal drug products is also being considered.

More vaccine manufacturing innovation investment is needed

The current COVID-19 pandemic will cost our economy an estimated $16 trillion dollars in the U.S. alone. The aforementioned Vaccine Analytics and Assays Center will significantly improve the response capability and capacity of vaccine companies to more rapidly develop and manufacture safe and effective vaccines. Vaccinating most people in the world is a required goal for winning the fight against this ongoing pandemic and current vaccines are likely to require booster doses. Rapid response to new variants of COVID-19, as well as other pandemics, such as influenza, will probably also become necessary.

As we move past society’s response to the COVID-19 pandemic and its variants, and look forward to the need to be better prepared for the next pandemic, one of the important lessons learned involves the need to ensure the availability of reliable manufacturing platforms. Having reliable and ready manufacturing platforms requires multiple elements: agile and unconstrained supply chains for materials and equipment needed to rapidly respond to a pandemic; available physical infrastructure to perform all of the manufacturing steps needed for vaccines and medical countermeasures; manufacturing innovations that enable manufacturing processes to be fast, agile, intensive, robust, and effective; and a skilled workforce that can be deployed for manufacturing operations.

The National Institute for Innovation in Manufacturing Biopharmaceuticals (NIIMBL) is a public-private partnership in the U.S. focused on manufacturing innovation for biopharmaceuticals including vaccines. NIIMBL seeks to collaboratively innovate manufacturing technologies and train a world-leading workforce in support of biopharmaceutical and vaccine manufacturing by working across stakeholders including biopharma manufacturers, suppliers, academia, community colleges, state governments, and Federal agencies. Like similar programs in other nations (for example, the United Kingdom’s Catapult program), NIIMBL focuses on global competitiveness in key advanced manufacturing fields.

Public-private partnerships, such as NIIMBL, create opportunities for stakeholders to develop and demonstrate important manufacturing- related technologies in the pre-competitive space. By co-investing in technology demonstrations of improved manufacturing technologies, participants develop a shared understanding of new technologies, collaborate to develop worker training programs, and advance the state of the art. Given the importance of vaccine development generally, and especially in the age of SARS-CoV-2, NIIMBL is looking forward to establishing a Vaccine Analytics and Assays Center that will help ensure rapid deployment of important analytical measures to accelerate the development timelines for new vaccines and facilitate rapid updates to analytical approaches used to ensure the safety and quality of vaccines deployed to the public.

This is an excerpt from an article that appeared in American Pharmaceutical Review on April 14, 2021. To read the complete article including references, click here.