Snakebite envenoming is a neglected tropical disease that requires immediate attention. Conventional plasma-derived snakebite antivenoms have existed for more than 120 years and have been ...instrumental in saving thousands of lives. However, both a need and an opportunity exist for harnessing biotechnology and modern drug development approaches to develop novel snakebite antivenoms with better efficacy, safety, and affordability. For this to be realized, though, development approaches, clinical testing, and manufacturing must be feasible for any novel treatment modality to be brought to the clinic. Here, we present engineering, manufacturing, and regulatory considerations that need to be taken into account for any development process for a novel antivenom product, with a particular emphasis on novel antivenoms based on mixtures of monoclonal antibodies. We highlight key drug development challenges that must be addressed, and we attempt to outline some of the important shifts that may have to occur in the ways snakebite antivenoms are designed and evaluated.
Snakebite envenoming is a neglected tropical disease that each year claims the lives of 80,000⁻140,000 victims worldwide. The only effective treatment against envenoming involves intravenous ...administration of antivenoms that comprise antibodies that have been isolated from the plasma of immunized animals, typically horses. The drawbacks of such conventional horse-derived antivenoms include their propensity for causing allergenic adverse reactions due to their heterologous and foreign nature, an inability to effectively neutralize toxins in distal tissue, a low content of toxin-neutralizing antibodies, and a complex manufacturing process that is dependent on husbandry and procurement of snake venoms. In recent years, an opportunity to develop a fundamentally novel type of antivenom has presented itself. By using modern antibody discovery strategies, such as phage display selection, and repurposing small molecule enzyme inhibitors, next-generation antivenoms that obviate the drawbacks of existing plasma-derived antivenoms could be developed. This article describes the conceptualization of a novel therapeutic development strategy for biosynthetic oligoclonal antivenom (BOA) for snakebites based on recombinantly expressed oligoclonal mixtures of human monoclonal antibodies, possibly combined with repurposed small molecule enzyme inhibitors.
Snakes, scorpions, and spiders are venomous animals that pose a threat to human health, and severe envenomings from the bites or stings of these animals must be treated with antivenom. Current ...antivenoms are based on plasma-derived immunoglobulins or immunoglobulin fragments from hyper-immunized animals. Although these medicines have been life-saving for more than 120 years, opportunities to improve envenoming therapy exist. In the later decades, new biotechnological tools have been applied with the aim of improving the efficacy, safety, and affordability of antivenoms. Within the avenues explored, novel immunization strategies using synthetic peptide epitopes, recombinant toxins (or toxoids), or DNA strings as immunogens have demonstrated potential for generating antivenoms with high therapeutic antibody titers and broad neutralizing capacity. Furthermore, these approaches circumvent the need for venom in the production process of antivenoms, thereby limiting some of the complications associated with animal captivity and venom collection. Finally, an important benefit of innovative immunization approaches is that they are often compatible with existing antivenom manufacturing setups. In this review, we compile all reported studies examining venom-independent innovative immunization strategies for antivenom development. In addition, a brief description of toxin families of medical relevance found in snake, scorpion, and spider venoms is presented, as well as how biochemical, bioinformatic, and omics tools could aid the development of next-generation antivenoms.
Snakebite envenoming is a neglected tropical disease that affects millions of people across the globe. It has been suggested that recombinant antivenoms based on mixtures of human monoclonal ...antibodies, which target key toxins of medically important snake venom, could present a promising avenue toward the reduction of morbidity and mortality of envenomated patients. However, since snakebite envenoming is a disease of poverty, it is pivotal that next-generation therapies are affordable to those most in need; this warrants analysis of the cost dynamics of recombinant antivenom manufacture. Therefore, we present, for the first time, a bottom-up analysis of the cost dynamics surrounding the production of future recombinant antivenoms based on available industry data. We unravel the potential impact that venom volume, abundance of medically relevant toxins in a venom, and the molecular weight of these toxins may have on the final product cost. Furthermore, we assess the roles that antibody molar mass, manufacturing and purification strategies, formulation, antibody efficacy, and potential cross-reactivity play in the complex cost dynamics of recombinant antivenom manufacture. Notably, according to our calculations, it appears that such next-generation antivenoms based on cocktails of monoclonal immunoglobulin Gs (IgGs) could be manufacturable at a comparable or lower cost to current plasma-derived antivenoms, which are priced at USD 13-1120 per treatment. We found that monovalent recombinant antivenoms based on IgGs could be manufactured for USD 20-225 per treatment, while more complex polyvalent recombinant antivenoms based on IgGs could be manufactured for USD 48-1354 per treatment. Finally, we investigated the prospective cost of manufacturing for recombinant antivenoms based on alternative protein scaffolds, such as DARPins and nanobodies, and highlight the potential utility of such scaffolds in the context of low-cost manufacturing. In conclusion, the development of recombinant antivenoms not only holds a promise for improving therapeutic parameters, such as safety and efficacy, but could possibly also lead to a more competetive cost of manufacture of antivenom products for patients worldwide.
Spiders and scorpions are notorious for their fearful dispositions and their ability to inject venom into prey and predators, causing symptoms such as necrosis, paralysis, and excruciating pain. ...Information on venom composition and the toxins present in these species is growing due to an interest in using bioactive toxins from spiders and scorpions for drug discovery purposes and for solving crystal structures of membrane-embedded receptors. Additionally, the identification and isolation of a myriad of spider and scorpion toxins has allowed research within next generation antivenoms to progress at an increasingly faster pace. In this review, the current knowledge of spider and scorpion venoms is presented, followed by a discussion of all published biotechnological efforts within development of spider and scorpion antitoxins based on small molecules, antibodies and fragments thereof, and next generation immunization strategies. The increasing number of discovery and development efforts within this field may point towards an upcoming transition from serum-based antivenoms towards therapeutic solutions based on modern biotechnology.
Oligoclonal mixtures of broadly-neutralizing antibodies can neutralize complex compositions of similar and dissimilar antigens, making them versatile tools for the treatment of e.g., infectious ...diseases and animal envenomations. However, these biotherapeutics are complicated to develop due to their complex nature. In this work, we describe the application of various strategies for the discovery of cross-neutralizing nanobodies against key toxins in coral snake venoms using phage display technology. We prepare two oligoclonal mixtures of nanobodies and demonstrate their ability to neutralize the lethality induced by two North American coral snake venoms in mice, while individual nanobodies fail to do so. We thus show that an oligoclonal mixture of nanobodies can neutralize the lethality of venoms where the clinical syndrome is caused by more than one toxin family in a murine challenge model. The approaches described may find utility for the development of advanced biotherapeutics against snakebite envenomation and other pathologies where multi-epitope targeting is beneficial.
Animal toxins present a major threat to human health worldwide, predominantly through snakebite envenomings, which are responsible for over 100,000 deaths each year. To date, the only available ...treatment against snakebite envenoming is plasma-derived antivenom. However, despite being key to limiting morbidity and mortality among snakebite victims, current antivenoms suffer from several drawbacks, such as immunogenicity and high cost of production. Consequently, avenues for improving envenoming therapy, such as the discovery of toxin-sequestering monoclonal antibodies against medically important target toxins through phage display selection, are being explored. However, alternative binding protein scaffolds that exhibit certain advantages compared to the well-known immunoglobulin G scaffold, including high stability under harsh conditions and low cost of production, may pose as possible low-cost alternatives to antibody-based therapeutics. There is now a plethora of alternative binding protein scaffolds, ranging from antibody derivatives (e.g., nanobodies), through rationally designed derivatives of other human proteins (e.g., DARPins), to derivatives of non-human proteins (e.g., affibodies), all exhibiting different biochemical and pharmacokinetic profiles. Undeniably, the high level of engineerability and potentially low cost of production, associated with many alternative protein scaffolds, present an exciting possibility for the future of snakebite therapeutics and merit thorough investigation. In this review, a comprehensive overview of the different types of binding protein scaffolds is provided together with a discussion on their relevance as potential modalities for use as next-generation antivenoms.
Ion channels play a crucial role in diverse physiological processes, including neurotransmission and muscle contraction. Venomous creatures exploit the vital function of ion channels by producing ...toxins in their venoms that specifically target these ion channels to facilitate prey capture upon a bite or a sting. Envenoming can therefore lead to ion channel dysregulation, which for humans can result in severe medical complications that often necessitate interventions such as antivenom administration. Conversely, the discovery of highly potent and selective venom toxins with the capability of distinguishing between different isoforms and subtypes of ion channels has led to the development of beneficial therapeutics that are now in the clinic. This review encompasses the historical evolution of electrophysiology methodologies, highlighting their contributions to venom and antivenom research, including venom-based drug discovery and evaluation of antivenom efficacy. By discussing the applications and advancements in patch-clamp techniques, this review underscores the profound impact of electrophysiology in unravelling the intricate interplay between ion channels and venom toxins, ultimately leading to the development of drugs for envenoming and ion channel-related pathologies.
Antivenom cross-reactivity has been investigated for decades to determine which antivenoms can be used to treat snakebite envenomings from different snake species. Traditionally, the methods used for ...analyzing cross-reactivity have been immunodiffusion, immunoblotting, enzyme-linked immunosorbent assay (ELISA), enzymatic assays, and in vivo neutralization studies. In recent years, new methods for determination of cross-reactivity have emerged, including surface plasmon resonance, antivenomics, and high-density peptide microarray technology. Antivenomics involves a top-down assessment of the toxin-binding capacities of antivenoms, whereas high-density peptide microarray technology may be harnessed to provide in-depth knowledge on which toxin epitopes are recognized by antivenoms. This review provides an overview of both the classical and new methods used to investigate antivenom cross-reactivity, the advantages and disadvantages of each method, and examples of studies using the methods. A special focus is given to antivenomics and high-density peptide microarray technology as these high-throughput methods have recently been introduced in this field and may enable more detailed assessments of antivenom cross-reactivity.
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