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Feliza Mirasol is the science editor for BioPharm International.
The emergence of new biotherapeutics is both the driver and result of innovative drug development technologies.
The emergence of new biotherapeutics has prompted the advancement of innovative technologies that enable or support unique approaches to biotherapeutic drug development, including vaccines. Some of these new technologies include intranasal formulation technology, new cell reprogramming technology, and virus-like particle technology, among others. The progress of drug development technologies will also have implications for the future direction of new biotherapeutic modalities.
The challenges to creating new biotherapeutic modalities stems from technical, scientific, and clinical advances that are resulting in a wider range of these modalities. This wider range of biologic modalities has led to a frequent requirement for bespoke development and characterization on a product-by-product basis to ensure that all possible interests, concerns, and compliance requirements of the international regulatory authorities have been considered and addressed, points out Margaret Temple, business development director of SGS.
“For example,” Temple explains, “Novel cell therapies have very limited or no downstream purification, which leads to a requirement to conduct very detailed safety testing and characterization of the cell bank and clinical product.”
“The development of COVID-19 vaccines in 2020 required an enhanced focus on documentation and study timelines to ensure lot-by-lot data [were] available in a coordinated and timely manner, whilst ensuring full compliance with the product release criteria,” she adds.
Joe Foster, chief operating officer of Mogrify, a UK-based cell therapy company, adds that all medicinal products have strict manufacturing and quality standards to follow to deliver safe and efficacious treatments to patients. In situations where the active pharmaceutical ingredient is biological, variation in the raw material and manufacturing process is difficult to eliminate entirely, which challenges the scalability of manufacturing biological modalities.
“In cell therapy,” Foster notes, “the most clinically successful cell type, T cells, currently follows a highly standardized ad-hoc manufacturing process where the quality of the final product is subject to the quality of the source cells initially isolated from the patient.”
“While ad-hoc protocols are associated with high costs and limited scalability, a challenge more broadly encountered in the translation of cells into safe and efficacious cell therapies is the need to modify, expand, and maintain cells in ex-vivo conditions, evident in the scant number of cell types that have been delivered to the clinic,” Foster adds.
Challenges such as these are what have driven the innovation being seen in drug development and manufacturing technologies. For example, it is expected that the rapid development and regulatory authority approval of several COVID-19 vaccines will lead to a shorter timeframe to develop and approve new biologics, says Temple. This shortened timeframe will be aided by developments in the availability of more rapid testing and techniques, such as in-vitro toxicology and next-generation sequencing, she adds.
Meanwhile, translating new technologies to commercial-scale production poses its own set of challenges. “Scaling up of cell culture is a continued challenge in the application of stem and primary cells as therapeutics when compared to the scale up of, for example, stable cell lines such as [those derived from] CHO [Chinese hamster ovary] cells (1),” says Temple.
“In scaling up new technologies, manufacturers are expected to account for the requirements to generate sufficient clinical material and additional material for testing and stability study purposes,” Temple emphasizes.
Another potential challenge, Temple says, is clarifying the chemistry, manufacturing, and controls (CMC)-related studies that must be performed if a novel technology (e.g., novel equipment, novel manufacturing process, and/or novel biological substrates) is used, as there is little or no precedence to follow. However, on the positive side, innovations in the use of synthetic raw materials and disposable equipment are expected to enhance manufacturing process development, she says.
Intranasal vaccines: the challenges
The furious pace with which COVID-19 vaccines were developed has shone a spotlight on the need for more agile responses to health emergencies, including the need for quicker and easier administration of vaccines. While not necessarily a new technological idea, intranasal vaccines is one potential answer to addressing the need for global administration. US-based Meissa Vaccines is working to develop an intranasal live-attenuated vaccine (LAV) for COVID-19, with Phase I trials already underway (2). Meissa’s vaccine candidate can be manufactured cost-effectively with single-dose immunity to meet global demand, according to Marty Moore, founder and CEO of Meissa Vaccines.
Meissa is overcoming traditional challenges in attenuating a live virus for use in an intranasal vaccine. “The attenuation of a virus to produce a vaccine must balance reducing its virulence while retaining its ability to stimulate an effective immune response, or immunogenicity,” says Moore. The company started out to develop a pediatric vaccine for respiratory syncytial virus (RSV). “Natural RSV infection does not stimulate a robust immune response, and immunity following SARS-CoV-2 infection wanes, so vaccine technologies, such as our AttenuBlock platform, that enhance immunogenicity are required,” Moore explains.
The traditional processes for making live attenuated vaccines involve serial passage, gene deletions, or other mutation strategies, he notes. “These strategies, however, typically affect the viral replication machinery, which can compromise immunogenicity of the vaccine candidate.”
Intranasal vaccines: call to innovation
In Meissa’s case, the development of its intranasal live attenuated recombinant vaccine also carries important opportunities as an end game vaccine for COVID-19. Moore uses the example of the live oral polio vaccine, which was successful in its ability to block transmission. Compared to the inactivated polio vaccine, the oral live attenuated (replicating) polio vaccine provided strong immunity and blocked transmission well. This example motivated the company in its development of an intranasal vaccine candidate.
“That’s our goal for our COVID-19 recombinant live attenuated vaccine: provide strong immunity with a single dose that’s intranasal with a high potential to effectively block transmission,” Moore states.
Meissa’s proprietary platform, known as AttenuBlock, uses synthetic biology to generate live attenuated RSV vaccine candidates designed to increase antigen expression and decrease or eliminate the expression genes that counteract the immune response. “The AttenuBlock platform incorporates 10 years of research and development at Emory University, where researchers employed rational and precise codon deoptimization and other genetic strategies to produce hundreds of targeted mutations into the RSV genome, providing exquisite control over viral protein expression,” Moore explains.
“We used codon deoptimization to reduce the efficiency of translating viral mRNA [messenger RNA] into proteins. By carefully selecting and replacing commonly used codons with nonpreferred codons in viral genes that inhibit the immune response, the translation of these viral mRNAs into proteins becomes inefficient. This approach results in heavy attenuation, optimized immunity, and genetic stability,” Moore further states.
For COVID-19, Moore points out that it is important to note that Meissa’s vaccine candidate is not a whole SARS-CoV-2. “Ours is designed as a live attenuated RSV backbone that expresses a fully functional SARS-CoV-2 spike protein, in place of the RSV antigen. The reason we did that is because coronaviruses, as a family of viruses, have a high rate of recombination, and viruses like RSV do not. We viewed that genetic instability of coronaviruses as a major hurdle to the development of a traditional live attenuated SARS-CoV-2,” he explains.
Live attenuated vaccines are typically manufactured on a cell line with relatively high productivity of doses/liter of capacity, resulting in a significantly lower footprint and cost of goods to manufacture. In addition, the dose of a live attenuated vaccine is typically much lower than all the other non-replicating vaccine types, including genetic (RNA/DNA), viral vectors, protein subunit, inactivated, and virus-like particles (VLPs). Thus, to meet global supply and demand, Meissa is implementing straightforward, economical, and scalable vaccine manufacturing technologies, Moore says.
“Meissa’s vaccine candidates grow well in cell culture to support manufacturing. Furthermore, Meissa’s single, low-dose vaccine candidates allow for a smaller manufacturing footprint and fewer batches to support production,” Moore states.
Virus-like particles: the challenges
When the pandemic began, Icosavax, a US-based biotechnology company pursuing VLP technology applied its technology platform to develop a vaccine candidate against COVID-19. The company’s vaccine program is supported by a $10 million grant from the Bill & Melinda Gates Foundation and $6.5 million from Open Philanthropy, a US-based research and grantmaking foundation (3).
“Although the application of VLP technology to the prevention of respiratory pathogens is fairly new, VLPs have been around for a long time,” says Adam Simpson, CEO of Icosavax. “In fact, licensed VLP vaccines are extremely effective. For example, naturally occurring VLPs have delivered effective licensed vaccines, including against human papillomavirus and hepatitis B.”
Simpson explains that VLP-based vaccines present key parts of the pathogen in a symmetrical and repetitive way, similar to how a virus would present itself. Meanwhile, the immune system has evolved to detect things that are presented thus as a danger signal and to react strongly to them. “However, reworking naturally occurring VLPs has been difficult to do for the display of proteins from certain pathogens, including those with complex heterologous antigens, such as RSV and SARS-CoV-2,” he states.
In Icosavax’s case, the company’s technology is designed to enable the use of VLP vaccine technology for a broader array of pathogen targets. Naturally occurring VLPs have historically induced strong, broad, and durable immunogenicity and protection, Simpson asserts. “However, naturally occurring VLP vaccines have limitations in displaying complex heterologous antigens. Our technology is designed to overcome this limitation to enable the incorporation of a broad array of complex heterologous antigens into VLP structures,” he says.
Virus-like particles: call to innovation
The idea behind Icosavax’s technology is based, not on reliance on molecules that naturally form VLPs, but rather on starting from scratch and using the power of computational protein design to create fully self-assembling proteins, Simpson explains. “We do not have to rely on the limits of what we see in nature, and we can optimize the particles accordingly via our technology,” he says.
Icosavax’s computationally designed VLP technology is designed to solve the problem of constructing and manufacturing VLPs displaying complex antigens. “The technology generates computationally designed proteins that separate the folding of individual protein subunits from the assembly of the final macromolecular structure. The individual proteins are expressed and purified using traditional recombinant technologies and then self-assemble into VLPs when mixed,” Simpson illustrates.
“We often describe our VLP technology as a soccer ball. The black parts are at the base of the antigens (e.g., the prefusion structure of the RSV F glycoprotein or the SARS-Co-V receptor binding domain) and the white parts are there as the second piece to help create an icosahedral particle in the middle of the vaccine. When mixed, the black and white parts self-assemble into the soccer ball, displaying the antigens in a repetitive fashion, much like a virus,” Simpson says.
However, the translation from lab-scale to commercial-scale production can be challenging if the technology was not designed with large-scale manufacturing processes and purification methods in mind, Simpson cautions. In addition, he adds, new technologies often have stability challenges at temperatures above sub-zero, which can lead to commercial distribution challenges.
“Our technology utilizes self-assembly of two protein components that can be manufactured using traditional recombinant protein manufacturing techniques. The technology is designed to be highly scalable and distributable,” Simpson says. Icosavax can use off-the-shelf technologies available at many recombinant protein contract manufacturers, he assures. “Both key intermediate components for IVX-411 [the company’s VLP COVID-19 vaccine candidate] have high manufacturing yield, and all data gathered to date support a competitive cost-of-goods. In addition, our final vaccine product is expected to be stable at 2–8 °C,” he adds.
Cell therapy development: the challenges
Mogrify, meanwhile, has developed a proprietary suite of platform technologies that utilize a systematic big-data approach to drive the speed, efficiency, and maintenance of cellular reprogramming. Its platform technologies have applications in generating the scalable source of functional cell types required to underpin the development of ex-vivo cell therapies and also the potential to pioneer a new class of in-vivo reprogramming therapies for indications of high unmet clinical need in immuno-oncology, ophthalmology, and other disease areas.
The main hurdle for a new technology such as this in its translation into viable biotherapies is proving clinical benefit and safety in vivo, Foster says. “In cases of innovative treatment modalities, especially, there is limited experience and historic data to refer to,” he emphasizes. In terms of the development of allogeneic cell therapies, for example, clinical efficacy has been proven through autologous cell therapies, but the use of pluripotent cells as a starting material and the integration of genetic modification requires thorough risk assessment for tumorigenicity and genetic instability, he explains.
Cell therapy development: a call to innovation.
“To deliver safer, more efficacious, and scalable cell therapy to patients, particularly in immunotherapy, developers are aiming to reduce toxicity-inducing factors, shift toward allogeneic cell therapies, and expand the range of clinically viable cell types,” says Foster.
He points out some current developmental trends, such as the use of gene-editing tools to remove immunogenic components, incorporate safety switches, and reduce the expression of cytokines associated with severe adverse events. He explains that the expansion of therapeutic cell types has seen progress in the increase of alternative cell types reaching clinical trials, such as natural killer cells and macrophages. This progress is accompanied by continuous efforts into the
characterization of rare subtypes with high levels of desired functionality, such as gamma delta T cells, and the discovery of new cell types through single-cell innovations.
“Taking inspiration from [K. Takahashi et al.’s] discovery of the OKSM [OCT4, SOX2, KLF4 and MYC] pluripotency-inducing factors (4), the field has been working to generate a universal induced pluripotent stem cell (iPSC) source for the derivation of any cell type of interest,” Foster says.
“Considerable effort has been invested into the development of off-the-shelf cell therapies derived from iPSCs; however, progress has been limited by the field’s ability to identify and recapitulate developmental pathways to freely differentiate target cell types from iPSCs whilst also acquiring and maintaining their required functional maturity for therapeutic purposes,” Foster adds.
In the meantime, with the increasing availability of high-throughput bioinformatics data, researchers have developed innovative computational approaches to systematically tackle the challenges posed by cellular reprogramming.
Platform technologies, such as MOGRIFY, utilize transcriptomic and regulatory network data to predict the key regulatory factors and small molecules that direct cellular reprogramming, Foster explains. Using the data in this way enables the transdifferentiation of any target cell type from any source cell type. Other complementary technologies, such as epiMOGRIFY, deploy epigenetics to predict optimal xenogen-free culture conditions for cell maintenance and to support cell reprogramming.
“When combined, such techniques provide a unique opportunity to enhance existing stem-cell-forward reprogramming methods or bypass development pathways altogether, allowing the direct reprogramming of the scalable source of functional cell types required to transform the development of ex-vivo cell therapies, and furthermore, the exploration of new classes of in-vivo reprogramming therapies, which offer the potential to introduce cell reprogramming in situ,” Foster emphasizes.
The future direction of drug development technologies may largely follow the near-term results of biotherapies currently in development and how they are handled. For example, the long-term prospects for mRNA vaccines are contingent on improving on the current cold temperature requirements for storage and shipment.
“If this is feasible, it would be expected that development of nucleic acid-based technologies progresses to develop products with other applications for healthcare, such as protein-based therapeutics. The international regulatory authorities have been supportive of advances in molecular biology, both with regard to product analysis and testing and with regard to product application, and this would be expected to continue,” Temple says. She further adds that it is not unreasonable to suggest that more product and clinical data and data analysis may be required to answer the question of what direction RNA-based therapeutics may take in the future, and to compare the application of nucleic acid technology with, for example, the application of cell-culture derived viral vaccines, which have been developed and approved for a significantly longer time.
Intranasal, vaccines generate both mucosal (IgA) antibodies in the nasal cavity and antibodies that circulate in the blood (serum), providing an alternative to injected vaccines, which typically do not do a sufficient job in blocking transmission, points out Moore.
“In contrast, injected vaccines typically induce circulating but not mucosal antibodies. While circulating antibodies are important for preventing serious lung disease, mucosal antibodies are important for blocking infection and transmission of respiratory viruses,” he states.
“We believe that end-game vaccines for COVID-19 need to be able to do both: prevent disease and block transmission,” Moore adds.
The preclinical data for Meissa’s COVID-19 recombinant LAV candidate shows that the vaccine induces a SARS-CoV-2-specific mucosal IgA response, causes the generation of serum-neutralizing antibodies, and provides efficacy against challenge, Moore emphasizes.
“With the current injected vaccines, we are going to need boosters for both durability and protection against variants. A real mucosal transmission-blocking vaccine could put a tight lid on SARS-CoV-2 and be an important end-game strategy to really put this to bed and get back to normal. That’s why we need intranasal vaccines,” Moore concludes.
Moore says that Meissa’s vaccine candidate has the potential to deliver a single-dose of 104–106 plaque-forming units (PFU)/dose compared with multiple doses of 109–1011 PFU/dose of non-replicating vaccines or multiple milligrams for subunit vaccines. “The footprint for manufacturing live attenuated vaccines is significantly smaller and does not necessitate single use technologies,” he also adds.
Meanwhile, an aging population also poses a challenge for traditional vaccine technology because the older a person gets, the more difficult it is to induce a robust immune response. “We believe that a technology that induces higher neutralizing antibody titers will have the best chance of optimal and lasting protection in older adults,” says Simpson
“Our vaccine candidates have shown a strong immune response in preclinical models, and we believe that our candidates could become important for older adults, where immunosenescence plays a role in the effectiveness and durability of other vaccine technologies,” Simpson states.
“Furthermore,” he continues, “from a global health and access perspective, the high yield and stability of the assembled VLPs suggest that manufacture of VLP vaccines will be highly scalable, and our final vaccine product is not expected to require subzero storage.”
The advantage of Icosavax’ technology is that it was designed to be highly scalable and distributable, according to Simpson.
“That said, COVID-19-related efforts have resulted in near-term shortages in materials, and, with the number and scale of existing vaccine manufacturing efforts worldwide, there are limited openings and manufacturing facilities. Right now, the biggest challenge we face is similar to many vaccines and therapeutic manufacturers in the current environment: access to facilities and materials needed for manufacturing and fill and finish at a large scale,” Simpson says.
“Currently, there are a small number of cell types that have been successfully delivered as therapies to the clinic, due to the limited capacity in directing cell fate and cell conversion,” says Foster, speaking from a company translating cell reprogramming into viable cell and gene therapies.
Mogrify is currently in the preclinical proof-of-concept stages of development, so discussion of commercial-scale aspects is early at this point; however, with the broad opportunities offered by the company’s proprietary technology platforms, its biggest challenge to date has been the identification, consolidation, and prioritization of the disease areas of focus, says Foster.
“We have chosen to focus on immuno-oncology and ophthalmology because they are both areas with clear regulatory pathways, and building on known therapeutic potential, will allow us to deploy our novel science and progress our lead assets within a well-defined clinical roadmap,” Foster states.
1. C. Du and C. Webb, “Cellular Systems,” in Comprehensive Biotechnology, pp. 11–23 (Elsevier, Amsterdam, Netherlands, Second Edition, 2011).
2. Meissa Vaccines, “Meissa Announces IND Clearance for Phase 1 Study of COVID-19 Intranasal Live Attenuated Vaccine,” Press Release, March 16, 2021.
3. Icosavax, “Icosavax Launches COVID-19 Vaccine Program with Preclinical Data and $16.5 Million in New Funding,” Press Release, Oct. 30, 2020.
4. K. Takahashi, et al., Cell 131 (5) 861–872 (2007).
Feliza Mirasol is the science editor for BioPharm International.
Vol. 34, No. 6
When referring to this article, please cite it as F. Mirasol, “Next-Gen Therapies Drive Development Technologies,” BioPharm International 34 (6) 2021.