Molecular Pharming: future targets and aspirations

Challenges and Strategies for Improving Access to Cancer Drugs in Malaysia: Summary of Opinions Expressed at the 2nd MACR International Scientific Conference 2022

Considerable progress has been made in cancer drug development in recent decades. However, for people in low- and middle-income countries, including Malaysia, many of these drugs are not readily available. During the 2nd Malaysian Association for Cancer Research (MACR) International Scientific Conference, a forum discussion was held to address these challenges and explore strategies to improve access to cancer medicines in the country. This paper presents the results of the said forum discussion. A few challenges to cancer drug access were highlighted, including lengthy approval and regulatory practices, cost of medicines, and manufacturing barriers. Besides, a few strategies for mitigating some of these challenges were proposed, such as mechanisms for cost reduction, uptake of biosimilars and generics, local manufacturing, public-private partnerships, strengthening the role of insurance companies, funding and regulation, and advocacy for fair pricing, by drawing examples from cancer medicines access initiatives in Malaysia and initiatives for different disease groups. Overall, this paper provides a comprehensive overview of the challenges and strategies for improving access to cancer medicines in Malaysia and provides valuable insights for policymakers, healthcare providers, the pharmaceutical industry, cancer patients, cancer support groups, and other stakeholders working on this important issue.

Efficiency Comparative Approach of Plant-Produced Monoclonal Antibodies against Rabies Virus Infection

Rabies encephalitis is a fatal zoonotic viral disease caused by the neurotropic rabies virus. It remains a major public health concern as it causes almost 100% fatality and has no effective medication after the onset of the disease. However, this illness is preventable with the timely administration of effective post-exposure prophylaxis (PEP) consisting of the rabies vaccine and passive immune globulins (HRIG and ERIG). Recently, conventional PEP has been shown to have many limitations, resulting in little support for these expensive and heterologous globulins. Monoclonal antibody (mAb) production via recombinant technology in animal and human cell cultures, as well as a plant-based platform, was introduced to overcome the costly and high-tech constraints of former preparations. We used transient expression technology to produce two mAbs against the rabies virus in Nicotiana benthamiana and compared their viral neutralizing activity in vitro and in vivo. The expression levels of selective mAbs E559 and 62-71-3 in plants were estimated to be 17.3 mg/kg and 28.6 mg/kg in fresh weight, respectively. The plant-produced mAbs effectively neutralized the challenge virus CVS-11 strain in a cell-based RFFIT. In addition, the combination of these two mAbs in a cocktail protected hamsters from rabies virus infection more effectively than standard HRIG and ERIG. This study suggests that the plant-produced rabies antibody cocktail has promising potential as an alternative biological to polyclonal RIG in rabies PEP.

Expression and immunogenicity assessment of a plant-made immunogen targeting the cytotoxic T-lymphocyte associated antigen-4: a possible approach for cancer immunotherapy

Cancer immunotherapy is a promising intervention to fight against this global health problem. In particular targeting immune checkpoints, such as cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) and programmed-death protein 1 (PD-1), by specific monoclonal antibodies is a current treatment for many malignances. A possible innovation in this field is based on the induction of humoral responses in the host by suppressing the effects of such immune checkpoints and as consequence favoring the activation of cellular immunity against the tumor cells. In this study, chimeric protein comprising the B subunit of Escherichia coli heat-labile enterotoxin as carrier and the extracellular domain of CTLA-4 (LTB-CTLA4) was produced in Nicotiana benthamiana by transient expression. The recombinant protein was accumulated up to 1.29 μg/g of leaves fresh weight on 4 day-post-infiltration. The integrity of the plant-made LTB-CTLA4 antigen was confirmed by western blot analysis and ELISA. Immunogenicity of the plant-made LTB-CTLA4 was assessed in BALB/c mice and the results showed that humoral responses were induced against both the LTB and CTLA-4 moieties. The plant-made LTB-CTLA4 stands as a promising candidate for the design of advanced protection studies against cancer in murine models.

New Hope for a "Cursed" Crop? Understanding Stakeholder Attitudes to Plant Molecular Farming With Modified Tobacco in Europe

Plant molecular farming (PMF) with tobacco could provide a sustainable and cheap platform for the production of high-value proteins for medical use. It could also offer European tobacco farmers an alternative, healthful end use for their crop. New plant breeding techniques (NPBTs) offer a means of quickly and precisely optimizing molecular farming platforms for this purpose. However, there has been little empirical research focussing on the barriers and facilitators of these technologies in the agricultural sphere. Here, we explore key stakeholder perceptions toward this combination of technologies, exploring their understanding of risk and opportunity. We interviewed N = 24 key stakeholders - tobacco farmers, agronomists, policymakers, and researchers - in three tobacco-growing areas of Spain and Italy. Our findings demonstrate these stakeholders have a favorable attitude toward PMF with tobacco due to its beneficial medical purpose and the opportunity it provides farmers to continue growing tobacco in a declining European market. Tobacco producers also reported favorable views toward NPBTs, though for some this was contingent on their use for non-food crops like tobacco. Most stakeholders' concerns are economic in nature, such as potential profitability and demands for new agronomic practices or infrastructure. Tobacco producer associations were thought to be important facilitators for future PMF scale-up. The attitude toward these technologies by smoking tobacco companies is, however, unknown and constitutes a potential risk to the development of PMF.

Shotguns vs Lasers: Identifying barriers and facilitators to scaling-up plant molecular farming for high-value health products

Plant molecular farming (PMF) is a convenient and cost-effective way to produce high-value recombinant proteins that can be used in the production of a range of health products, from pharmaceutical therapeutics to cosmetic products. New plant breeding techniques (NPBTs) provide a means to enhance PMF systems more quickly and with greater precision than ever before. However, the feasibility, regulatory standing and social acceptability of both PMF and NPBTs are in question. This paper explores the perceptions of key stakeholders on two European Union (EU) Horizon 2020 programmes-Pharma-Factory and Newcotiana-towards the barriers and facilitators of PMF and NPBTs in Europe. One-on-one qualitative interviews were undertaken with N = 20 individuals involved in one or both of the two projects at 16 institutions in seven countries (Belgium, France, Germany, Italy, Israel, Spain and the UK). The findings indicate that the current EU regulatory environment and the perception of the public towards biotechnology are seen as the main barriers to scaling-up PMF and NPBTs. Competition from existing systems and the lack of plant-specific regulations likewise present challenges for PMF developing beyond its current niche. However, respondents felt that the communication of the benefits and purpose of NPBT PMF could provide a platform for improving the social acceptance of genetic modification. The importance of the media in this process was highlighted. This article also uses the multi-level perspective to explore the ways in which NPBTs are being legitimated by interested parties and the systemic factors that have shaped and are continuing to shape the development of PMF in Europe.

Stable Expression of Adalimumab in Nicotiana tabacum

Production of monoclonal antibodies and pharmaceutical proteins in transgenic plants has been the focus of many research efforts for close to 30 years. Use of plants as bioreactors reduces large-scale production costs and minimizes risk for human pathogens contamination. Stable nuclear transformation of the plant genome offers a clear advantage in agricultural protein production platforms, limited only by the number of hectares that can be cultivated. We report here, for the first time, successful and stable expression of adalimumab in transgenic Nicotiana tabacum plants. The plant-derived adalimumab proved fully active and was shown to rescue L929 cells from the in vitro lethal effect of rhTNFα just as effectively as commercially available CHO-derived adalimumab (Humira). These results indicate that agricultural biopharming is an efficient alternative to mammalian cell-based expression platforms for the large-scale production of recombinant antibodies.

The Concept of Biosimilars: From Characterization to Evolution-A Narrative Review

Biologic agents are currently the fastest emerging segment of drug expenditure. Unlike chemically synthesized small-molecule drugs, biologics are more complex, medicinal products produced by a living organism. They have become part of the standard of care in the treatment of a large variety of diseases, such as growth disorders, autoimmune diseases, cancer, cardiovascular illnesses, hemophilia, and rare genetic conditions, to name a few. Biosimilars, which are copies of biologics that are highly similar, were introduced in the market with an aim to offer efficacy that is not clinically different from the originator or reference product, at lower prices. We aim to clarify the concept of biosimilar, from definitions, history, market entry, challenges faced, and future evolution. For that purpose, we performed a literature search on the sites of the medicines regulatory agencies and PubMed from 1990 to 2014 with the keywords "biosimilars," "market," and "regulatory." In 2006, the first biosimilar, somatropin [rDNA origin], was marketed and led the way for biosimilar drug manufacturing. As a result, manufacturers have entered a diversified competition, facing challenges in manufacturing these complex agents, such as immunogenicity and efficiency. Biosimilars are set to evolve differently in various markets, namely the U.S., Japan, the European Union, and the "pharmerging" economies.

IMPLICATIONS FOR PRACTICE

This article highlights the importance of biosimilars, as a cost-cutting strategy, in the delivery of state-of-the-art health care in developing countries, at a fraction of what a reference biological agent would cost.

Plasma-Derived Polyreactive Secretory-Like IgA and IgM Opsonizing Salmonella enterica Typhimurium Reduces Invasion and Gut Tissue Inflammation through Agglutination

Due to the increasing emergence of antibiotic-resistant strains of enteropathogenic bacteria, development of alternative treatments to fight against gut infections is a major health issue. While vaccination requires that a proper combination of antigen, adjuvant, and delivery route is defined to elicit protective immunity at mucosae, oral delivery of directly active antibody preparations, referred to as passive immunization, sounds like a valuable alternative. Along the gut, the strategy suffers, however, from the difficulty to obtain sufficient amounts of antibodies with the appropriate specificity and molecular structure for mucosal delivery. Physiologically, at the antibody level, the protection of gastrointestinal mucosal surfaces against enteropathogens is principally mediated by secretory IgA and secretory IgM. We previously demonstrated that purified human plasma-derived IgA and IgM can be associated with secretory component to generate biologically active secretory-like IgA and IgM (SCIgA/M) that can protect epithelial cells from infection by Shigella flexneri in vitro. In this study, we aimed at evaluating the protective potential of these antibody preparations in vivo. We now establish that such polyreactive preparations bind efficiently to Salmonella enterica Typhimurium and trigger bacterial agglutination, as observed by laser scanning confocal microscopy. Upon delivery into a mouse ligated intestinal loop, SCIgA/M-mediated aggregates persist in the intestinal environment and limit the entry of bacteria into intestinal Peyer’s patches via immune exclusion. Moreover, oral administration to mice of immune complexes composed of S. Typhimurium and SCIgA/M reduces mucosal infection, systemic dissemination, and local inflammation. Altogether, our data provide valuable clues for the future appraisal of passive oral administration of polyreactive plasma-derived SCIgA/M to combat infection by a variety of enteropathogens.

Exploiting virus-like particles as innovative vaccines against emerging viral infections

Emerging viruses pose a major threat to humans and livestock with global public health and economic burdens. Vaccination remains an effective tool to reduce this threat, and yet, the conventional cell culture often fails to produce sufficient vaccine dose. As an alternative to cell-culture based vaccine, virus-like particles (VLPs) are considered as a highpriority vaccine strategy against emerging viruses. VLPs represent highly ordered repetitive structures via macromolecular assemblies of viral proteins. The particulate nature allows efficient uptake into antigen presenting cells stimulating both innate and adaptive immune responses towards enhanced vaccine efficacy. Increasing research activity and translation opportunity necessitate the advances in the design of VLPs and new bioprocessing modalities for efficient and cost-effective production. Herein, we describe major achievements and challenges in this endeavor, with respect to designing strategies to harnessing the immunogenic potential, production platforms, downstream processes, and some exemplary cases in developing VLP-based vaccines.

Efficient genetic transformation and regeneration system from hairy root of Origanum vulgare

Origanum vulgare L is commonly known as a wild marjoram and winter sweet which has been used in the traditional medicine due to its therapeutic effects as stimulant, anticancer, antioxidant, antibacterial, anti-inflammatory and many other diseases. A reliable gene transfer system via Agrobacterium rhizogenes and plant regeneration via hairy roots was established in O. vulgare for the first time. The frequency of induced hairy roots was different by modification of the co-cultivation medium elements after infection by Agrobacterium rhizogenes strains K599 and ATCC15834. High transformation frequency (91.3 %) was achieved by co-cultivation of explants with A. rhizogenes on modified (MS) medium. The frequency of calli induction with an 81.5 % was achieved from hairy roots on MS medium with 0.25 mg/L(-1) 2,4-D. For shoot induction, initiated calli was transferred into a medium containing various concentrations of BA (0.1, 0.25, 0.5, 0.75 and 1 mg/L(-1)). The frequency of shoot generation (85.18 %) was achieved in medium fortified with 0.25 mg/L(-1) of BA. Shoots were placed on MS medium with 0.25 mg/l IBA for root induction. Roots appeared and induction rate was achieved after 15 days.

Efficient genetic transformation and regeneration system from hairy root of Origanum vulgare

Origanum vulgare L is commonly known as a wild marjoram and winter sweet which has been used in the traditional medicine due to its therapeutic effects as stimulant, anticancer, antioxidant, antibacterial, anti-inflammatory and many other diseases. A reliable gene transfer system via Agrobacterium rhizogenes and plant regeneration via hairy roots was established in O. vulgare for the first time. The frequency of induced hairy roots was different by modification of the co-cultivation medium elements after infection by Agrobacterium rhizogenes strains K599 and ATCC15834. High transformation frequency (91.3 %) was achieved by co-cultivation of explants with A. rhizogenes on modified (MS) medium. The frequency of calli induction with an 81.5 % was achieved from hairy roots on MS medium with 0.25 mg/L(-1) 2,4-D. For shoot induction, initiated calli was transferred into a medium containing various concentrations of BA (0.1, 0.25, 0.5, 0.75 and 1 mg/L(-1)). The frequency of shoot generation (85.18 %) was achieved in medium fortified with 0.25 mg/L(-1) of BA. Shoots were placed on MS medium with 0.25 mg/l IBA for root induction. Roots appeared and induction rate was achieved after 15 days.

Current Status and Development of Vaccines and Other Biologics for Human Rabies Prevention

Rabies is a neglected viral zoonosis with the highest case fatality of any infectious disease. Pasteur's historical accomplishments during the late 19(th) century began the process of human vaccine development, continuing to evolve into the 21(st) century. Over the past 35 years, great improvements occurred in the production of potent tissue culture vaccines and the gradual removal from the market of unsafe nerve tissue products. Timely and appropriate administration of modern biologics virtually assures survivorship, even after severe exposures. Nevertheless, in the developing world, if not provided for free nationally, the cost of a single course of human prophylaxis exceeds the average monthly wage of the common worker. Beyond traditional approaches, recombinant, sub-unit and other novel methods are underway to improve the availability of safe, effective and more affordable rabies biologics.

Assessment of heat shock protein 70 induction by heat in alfalfa varieties and constitutive overexpression in transgenic plants

Heat shock proteins (HSPs) are molecular chaperones involved in many cellular functions. It has been shown that mammalian cytosolic HSP70 binds antigenic peptides mediating the activation of the immune system, and that it plays a determining role in tumour immunogenicity. This suggests that HSP70 may be used for the production of conjugated vaccines. Human and plant HSPs share high sequence similarity and some important biological functions in vitro. In addition, plant HSPs have no endotoxic side effects. Extraction of HSP70 from plants for use as vaccine adjuvant requires enhancing its concentration in plant tissues. In this work, we explored the possibility to produce HSP70 in both transgenic and non-transgenic plants, using alfalfa as a model species. First, a transcriptional analysis of a constitutive and an inducible HSP70 genes was conducted in Arabidopsis thaliana. Then the coding sequence of the inducible form was cloned and introduced into alfalfa by Agrobacterium-mediated transformation, and the accumulation of the protein in leaf tissue of transgenic plants was demonstrated. We also tested diverse alfalfa varieties for heat-inducible expression of endogenous HSP70, revealing variety-specific responses to heat shock.

Marine Algae: a Source of Biomass for Biotechnological Applications

Biomass derived from marine microalgae and macroalgae is globally recognized as a source of valuable chemical constituents with applications in the agri-horticultural sector (including animal feeds and health and plant stimulants), as human food and food ingredients as well as in the nutraceutical, cosmeceutical, and pharmaceutical industries. Algal biomass supply of sufficient quality and quantity however remains a concern with increasing environmental pressures conflicting with the growing demand. Recent attempts in supplying consistent, safe and environmentally acceptable biomass through cultivation of (macro- and micro-) algal biomass have concentrated on characterizing natural variability in bioactives, and optimizing cultivated materials through strain selection and hybridization, as well as breeding and, more recently, genetic improvements of biomass. Biotechnological tools including metabolomics, transcriptomics, and genomics have recently been extended to algae but, in comparison to microbial or plant biomass, still remain underdeveloped. Current progress in algal biotechnology is driven by an increased demand for new sources of biomass due to several global challenges, new discoveries and technologies available as well as an increased global awareness of the many applications of algae. Algal diversity and complexity provides significant potential provided that shortages in suitable and safe biomass can be met, and consumer demands are matched by commercial investment in product development.

Engineering, expression in transgenic plants and characterisation of E559, a rabies virus-neutralising monoclonal antibody

Rabies post-exposure prophylaxis (PEP) currently comprises administration of rabies vaccine together with rabies immunoglobulin (RIG) of either equine or human origin. In the developing world, RIG preparations are expensive, often in short supply, and of variable efficacy. Therefore, we are seeking to develop a monoclonal antibody cocktail to replace RIG. Here, we describe the cloning, engineering and production in plants of a candidate monoclonal antibody (E559) for inclusion in such a cocktail. The murine constant domains of E559 were replaced with human IgG1κ constant domains and the resulting chimeric mouse-human genes were cloned into plant expression vectors for stable nuclear transformation of Nicotiana tabacum. The plant-expressed, chimeric antibody was purified and biochemically characterized, was demonstrated to neutralize rabies virus in a fluorescent antibody virus neutralization assay, and conferred protection in a hamster challenge model.

Single-dose monomeric HA subunit vaccine generates full protection from influenza challenge

Recombinant subunit vaccines are an efficient strategy to meet the demands of a possible influenza pandemic, because of rapid and scalable production. However, vaccines made from recombinant hemagglutinin (HA) subunit protein are often of low potency, requiring high dose or boosting to generate a sustained immune response. We have improved the immunogenicity of a plant-made HA vaccine by chemical conjugation to the surface of the Tobacco mosaic virus (TMV) which is non infectious in mammals. We have previously shown that TMV is taken up by mammalian dendritic cells and is a highly effective antigen carrier. In this work, we tested several TMV-HA conjugation chemistries, and compared immunogenicity in mice as measured by anti-HA IgG titers and hemagglutination inhibition (HAI). Importantly, pre-existing immunity to TMV did not reduce initial or boosted titers. Further optimization included dosing with and without alum or oil-in water adjuvants. Surprisingly, we were able to stimulate potent immunogenicity and HAI titers with a single 15 µg dose of HA as a TMV conjugate. We then evaluated the efficacy of the TMV-HA vaccine in a lethal virus challenge in mice. Our results show that a single dose of the TMV-HA conjugate vaccine is sufficient to generate 50% survival, or 100% survival with adjuvant, compared with 10% survival after vaccination with a commercially available H1N1 vaccine. TMV-HA is an effective dose-sparing influenza vaccine, using a single-step process to rapidly generate large quantities of highly effective flu vaccine from an otherwise low potency HA subunit protein.

How can plant genetic engineering contribute to cost-effective fish vaccine development for promoting sustainable aquaculture?

Aquaculture, the fastest growing food-producing sector, now accounts for nearly 50 % of the world's food fish (FAO in The state of world fisheries and aquaculture. FAO, Rome, 2010). The global aquaculture production of food fish reached 62.7 million tonnes in 2011 and is continuously increasing with an estimated production of food fish of 66.5 million tonnes in 2012 (a 9.4 % increase in 1 year, FAO, www.fao.org/fishery/topic/16140 ). Aquaculture is not only important for sustainable protein-based food fish production but also for the aquaculture industry and economy worldwide. Disease prevention is the key issue to maintain a sustainable development of aquaculture. Widespread use of antibiotics in aquaculture has led to the development of antibiotic-resistant bacteria and the accumulation of antibiotics in the environment, resulting in water and soil pollution. Thus, vaccination is the most effective and environmentally-friendly approach to combat diseases in aquaculture to manage fish health. Furthermore, when compared to >760 vaccines against human diseases, there are only about 30 fish vaccines commercially available, suggesting the urgent need for development and cost-effective production of fish vaccines for managing fish health, especially in the fast growing fish farming in Asia where profit is minimal and therefore given high priority. Plant genetic engineering has made significant contributions to production of biotech crops for food, feed, valuable recombinant proteins etc. in the past three decades. The use of plants for vaccine production offers several advantages such as low cost, safety and easy scaling up. To date a large number of plant-derived vaccines, antibodies and therapeutic proteins have been produced for human health, of which a few have been made commercially available. However, the development of animal vaccines in plants, especially fish vaccines by genetic engineering, has not yet been addressed. Therefore, there is a need to exploit plant biotechnology for cost effective fish vaccine development in plants, in particular, edible crops for oral fish vaccines. This review provides insight into (1) the current status of fish vaccine and vaccination in aquaculture, (2) plant biotechnology and edible crops for fish vaccines for oral administration, (3) regulatory constraints and (4) conclusions and future perspectives.

Combinatorial Analysis of Secretory Immunoglobulin A (sIgA) Expression in Plants

Delivery of secretory immunoglobulin A (sIgA) to mucosal surfaces as a passive immunotherapy agent is a promising strategy to prevent infectious diseases. Recombinant sIgA production in plants requires the co-expression of four transcriptional units encoding the light chain (LC), heavy chain (HC), joining chain (JC) and secretory component (SC). As a way to optimize sIgA production in plants, we tested the combinatorial expression of 16 versions of a human sIgA against the VP8* rotavirus antigen in Nicotiana benthamiana, using the recently developed GoldenBraid multigene assembly system. Each sIgA version was obtained by combining one of the two types of HC (α1 and α2) with one of the two LC types (k and λ) and linking or not a KDEL peptide to the HC and/or SC. From the analysis of the anti-VP8* activity, it was concluded that those sIgA versions carrying HCα1 and LCλ provided the highest yields. Moreover, ER retention significantly increased antibody production, particularly when the KDEL signal was linked to the SC. Maximum expression levels of 32.5 μg IgA/g fresh weight (FW) were obtained in the best performing combination, with an estimated 33% of it in the form of a secretory complex.

Virus Glycoproteins Tagged with the Human Fc Domain as Second Generation Vaccine Candidates

Traditional vaccines such as inactivated or live attenuated vaccines, are gradually giving way to more biochemically defined vaccines that are most often based on a recombinant antigen known to possess neutralizing epitopes. Such vaccines can offer improvements in speed, safety and manufacturing process but an inevitable consequence of their high degree of purification is that immunogenicity is reduced through the lack of the innate triggering molecules present in more complex preparations. Targeting recombinant vaccines to antigen presenting cells (APCs) such as dendritic cells however can improve immunogenicity by ensuring that antigen processing is as efficient as possible. Immune complexes, one of a number of routes of APC targeting, are mimicked by a recombinant approach, crystallizable fragment (Fc) fusion proteins, in which the target immunogen is linked directly to an antibody effector domain capable of interaction with receptors, FcR, on the APC cell surface. A number of virus Fc fusion proteins have been expressed in insect cells using the baculovirus expression system and shown to be efficiently produced and purified. Their use for immunization next to non-Fc tagged equivalents shows that they are powerfully immunogenic in the absence of added adjuvant and that immune stimulation is the result of the Fc-FcR interaction.