Polyspecificity - An emerging trend in the development of clinical antibodies

Monoclonal Antibodies for Pediatric Viral Disease Prevention and Treatment

Medical advancements over the last century have improved our ability to treat pediatric infectious diseases, significantly reducing associated morbidity and mortality worldwide. Although vaccines have been pivotal in this progress, many viral pathogens still do not currently have effective vaccines. The COVID-19 pandemic highlighted the need for rapid responses to emerging viral pathogens and introduced new tools to combat them. This review addresses human monoclonal antibodies (mAbs) as a strategy for treating and preventing viral infections in pediatric populations. We discuss previously used and currently available mAbs and advancements in mAb discovery. We address the future of mAb therapy by describing novel approaches in drug production and delivery platforms in addition to alternative antibody classes. Finally, we review the challenges and limitations of mAb therapy development for newborns and children.

A machine learning framework to identify complex physicochemical features of B cell epitopes

During infection with Plasmodium falciparum in pregnancy, parasites express a unique virulence factor, VAR2CSA, that mediates binding of infected red blood cells to the placenta. A major goal in designing vaccines to protect pregnant women from malaria is to elicit antibodies to VAR2CSA. The challenge is that VAR2CSA is highly polymorphic and identifying conserved epitopes is essential to elicit strain-transcending immunity. Unexpectedly, a mouse monoclonal antibody, 3D10, raised against the unrelated Duffy binding protein from P. vivax (DBPII) cross-reacts with diverse alleles of VAR2CSA in vitro. To identify these potentially conserved epitopes in VAR2CSA, we designed a machine learning framework to analyse 3D10 reactivity to peptides derived from two alleles of VAR2CSA, DBPII, and PvEBP2 (negative control). We used decision trees and a panel of 430 features to extract features correlated to 3D10 binding. We analysed patterns of these features in the dataset and designed mutant peptides to test complex sequence motifs. Features associated with 3D10 reactivity were mapped onto predicted 3D structures of Plasmodium proteins and validated based on 3D10 reactivity to the recombinant antigens. While the array data identified certain linear epitopes, the framework predicted other epitopes that are conformational. With this approach, peptide array data can be mined to extract physicochemical properties of epitopes recognized by polyreactive antibodies.

Bispecific domain antibody attenuates airway hyperresponsiveness and pulmonary inflammation in ovalbumin-lipopolysaccharide induced asthma model by inhibiting IL-23 and TNF-α

Asthma, a chronic multi-factorial pulmonary inflammatory condition with a high morbidity rate, is characterized by airway hyperresponsiveness and persistent pulmonary inflammation. There is a need to develop more effective treatment(s) for the management of asthma. In this study, we have investigated the therapeutic potential of BiSpekDAb (an engineered bispecific antibody comprising an anti-IL-23 domain antibody and an anti-TNF-α domain antibody fused together via flexible linkers to a half-life extension partner) in asthma. Asthma was established by sensitization and challenge of female Wistar rats with the combination of ovalbumin and lipopolysaccharide and the efficacy of BiSpekDAb was investigated by its subcutaneous administration for 11 days on each alternative day (6 doses) during the challenge phase. Significant deterioration of pulmonary functions, enhanced airway hyperresponsiveness, increase in the number of immune cells such as lymphocytes, eosinophils, neutrophils in blood circulation as well as in lungs, enhanced production of inflammatory cytokines (IL-23, TNF-α, IL-1β, IL-6, IL-22), allergic IgE antibodies, oxidative stress markers, and histopathological changes (thickening of epithelial lining, infiltration of immune cells, mast cell degranulation, and overproduction of mucus) were observed in asthma animals, and administration of BiSpekDAb attenuated airway hyperresponsiveness (AHR), pulmonary inflammation and other pathological changes. BiSpekDAb significantly inhibited IL-23 and TNF-α levels in the lungs of asthmatic rats. Our results suggest that targeting IL-23 and TNF-α simultaneously opens a new therapeutic window for biologics development aimed at mitigating pulmonary inflammation such as asthma.

Nanobody-Oligonucleotide Conjugates (NucleoBodies): The Next Frontier in Oligonucleotide Therapy

As of now, more than 15 oligonucleotide drugs, primarily small interfering RNAs and antisense oligonucleotide classes, have been approved by the US FDA for therapeutic use, and many more are under clinical trials. However, safe and effective delivery of the oligonucleotide-based drugs to the target tissue still remains a major challenge. For enhanced plasma half-life, effective endosomal release, and other multiple functionalities, various carrier molecules have been used over the years. The successful therapeutic application of antibody-drug conjugates has made antibodies a popular choice for the delivery of oligonucleotide payloads into the target tissues. Single-chain variable domains of heavy chain antibodies (nanobodies) have proven a promising alternative to antibodies in recent years due to their small size, high affinity for the target, cell-penetrating potency, simple and easy production. The present review highlights the oligonucleotide drug types and their conjugation with nanobodies called NucleoBodies for effective targeted delivery, detection and diagnostics.

Human Paraoxonase 1: From Bloodstream Enzyme to Disease Fighter & Therapeutic Intervention

Human paraoxonase 1 (hPON1) is a Ca2+-dependent metalloenzyme with multifunctional properties. Due to its diverse activities (arylesterase, phosphotriesterase, and lactonase), it plays a significant role in disease conditions. Researchers across the globe have demonstrated different properties of PON1, like anti-oxidant, anti-inflammatory, anti-atherogenic, anti-diabetic, and OPneutralization. Due to its pleotropic role in disease conditions like atherosclerosis, diabetes, cardiovascular diseases, neurodegenerative disorders, and OP-poisoning, it can be considered as a potential candidate for the development of therapeutic interventions. Attempts are being made in this direction to identify the exact role of PON1 in these disease conditions. Different approaches like directed evolution, genetic as well as chemical fusion, liposomal delivery of PON1, etc., are being developed and evaluated for their therapeutic effects in different pathological conditions. In this review, we outline the exact role and involvement of different properties of PON1 in the pathophysiology of different diseases and how it can be utilized and developed as a therapeutic intervention in PON1-associated disease conditions.

Antigen Specificity: A Fluctuating Aspect in the Development of Clinical Antibodies?

Development of antibodies for clinical use is a complex process involving numerous aspects, with antigen specificity being the most important. Initially, polyclonal antibodies, that can recognize multiple specific and nonspecific antigens (polyreactive), were developed and were very effective in the treatments. Later on, the polyspecificity/polyreactivity of these polyclonal antibodies (binding to multiple antigens) raised concerns about therapeutic efficacy because of their nonspecific interactions and challenges, such as development of immune complexes, batch-to-batch variability. This highlighted the need for more targeted approaches. It was resolved by the marked invention of hybridoma technology in 1975 which resulted in the revolution in the antibody development field by offering monoclonal monospecific antibodies (bind single antigen). However, their limited application in complex pathologies sparked a paradigm shift, leading to the resurgence of polyspecific antibodies in the form of monoclonal polyspecific antibodies (Polybodies), which bind multiple antigens, but specifically. Till today, 14 Polybodies are approved for clinical use. This fluctuation in antigen specificity is directing the evolution of engineered antibodies that are going to drive the biopharmaceutical sector in the coming years. Through this write-up, we assert the fluctuating nature of antigen specificity during the antibody development and how it will be crucial for advancing biologics.

Polybodies: Next-generation clinical antibodies

Conventional antibodies [full-length and fragments: F(ab')2, fragment antigen-binding (Fab), single-chain variable fragment (scFv), variable heavy domain of heavy chain antibody (VHH)] are monospecific, first-generation antibodies, that have dominated the biopharmaceuticals field. However, protein engineering approaches has led to the advent of the next-generation antibodies (polybodies), which are significant improvement over the conventional antibodies. Polybodies comprise polyspecific and/or polyvalent antibodies that enable a single antibody to target multiple specific antigens simultaneously. Polybodies are superior to first-generation antibodies (more efficacious, broad-spectrum, resistance resilient, customizable, etc.) and provide a cost-effective healthcare solution. This review addresses recent developments in polybodies, highlighting their superiority over conventional antibodies and offering future perspectives to encourage the generation of innovative immunotherapies.

Overcoming limitations and advancing the therapeutic potential of antibody-oligonucleotide conjugates (AOCs): Current status and future perspectives

As cancer incidence rises due to an aging population, the importance of precision medicine continues to grow. Antibody-drug conjugates (ADCs) exemplify targeted therapies by delivering cytotoxic agents to specific antigens. Building on this concept, researchers have developed antibody-oligonucleotide conjugates (AOCs), which combine antibodies with oligonucleotides to regulate gene expression. This review highlights the mechanism of AOCs, emphasizing their unique ability to selectively target and modulate disease-causing proteins. It also explores the components of AOCs and their application in tumor therapy while addressing key challenges such as manufacturing complexities, endosomal escape, and immune response. The article underscores the significance of AOCs in precision oncology and discusses future directions, highlighting their potential in treating cancers driven by genetic mutations and abnormal protein expression.

Engineered polyspecific antibodies: A new frontier in the field of immunotherapeutics

The 21st-century beginning remarked with the huge success of monospecific MAbs, however, in the last couple of years, polyspecific MAbs (PsAbs) have been an interesting topic and show promise of being biobetter than monospecific MAbs. Polyspecificity, in which a single antibody serves multiple specific target binding, has been hypothesized to contribute to the development of a highly effective antibody repertoire for immune defence. This polyspecific MAb trend represents an explosion that is gripping the whole pharmaceutical industry. This review is concerned with the current development and quality enforcement of PsAbs. All provided literature on monospecific MAbs and polyspecific MAbs (PsAbs) were searched using various electronic databases such as PubMed, Google Scholar, Web of Science, Elsevier, Springer, ACS, Google Patent and books via the keywords Antibody engineering, Polyspecific antibody, Conventional antibody, non-conventional antibody, and Single domain antibody. In the literature, there are more than 100 different formats to construct PsAb by quadroma technology, chemical conjugation and genetic engineering. Till March 2023, nine PsAb have been approved around the world, and around 330 are in advanced developmental stages, showing the dominancy of PsAb in the growing health sector. Recent advancements in protein engineering techniques and the fusion of non-conventional antibodies have made it possible to create complex PsAbs that demonstrate higher stability and enhanced potency. This marks the most significant achievement for cancer immunotherapy, in which PsAbs have immense promise. It is worth mentioning that seven out of the nine PsAbs have been approved as anti-cancer therapy. As PsAbs continue to acquire prominence, they could pave the way for the development of novel immunotherapies for multiple diseases.

Polyvalency: an emerging trend in the development of clinical antibodies

Medicine has benefited greatly from the development of monoclonal antibody (mAb) technology. First-generation mAbs have seen significant success in the treatment of major diseases, such as autoimmune, inflammation, cancer, infectious, and cardiovascular diseases. Developing next-generation antibodies with improved potency, safety, and non-natural characteristics is a booming field of mAb research. In this review, we discuss the significance of polyvalency and polyvalent antibodies, as well as important findings from preclinical studies and clinical trials involving polyvalent antibodies. We then review the role of tumor necrosis factor-alpha (TNF-α) in inflammatory diseases and the need for polyvalent anti-TNF-α antibodies.

Structural analysis of light chain-driven bispecific antibodies targeting CD47 and PD-L1

In contrast to natural antibodies that rely mainly on the heavy chain to establish contacts with their cognate antigen, we have developed a bispecific antibody format in which the light chain (LC) drives antigen binding and specificity. To better understand epitope-paratope interactions in this context, we determined the X-ray crystallographic structures of an antigen binding fragment (Fab) in complex with human CD47 and another Fab in complex with human PD-L1. These Fabs contain a κ-LC and a λ-LC, respectively, which are paired with an identical heavy chain (HC). The structural analysis of these complexes revealed the dominant contribution of the LCs to antigen binding, but also that the common HC provides some contacts in both CD47 and PD-L1 Fab complexes. The anti-CD47 Fab was affinity optimized by diversifying complementary-determining regions of the LC followed by phage display selections. Using homology modeling, the contributions of the amino acid modification to the affinity increase were analyzed. Our results demonstrate that, despite a less prominent role in natural antibodies, the LC can mediate high affinity binding to different antigens and neutralize their biological function. Importantly, Fabs containing a common variable heavy (VH) domain enable the generation of bispecific antibodies retaining a truly native structure, maximizing their therapeutic potential.

Recombinant human endostatin as a potential anti-angiogenic agent: therapeutic perspective and current status

Angiogenesis is the physiological process that results in the formation of new blood vessels develop from pre-existing vasculature and plays a significant role in several physiological and pathological processes. Inhibiting angiogenesis, a crucial mechanism in the growth and metastasis of cancer, has been proposed as a potential anticancer therapy. Different studies showed the beneficial effects of angiogenesis inhibitors either in patients suffering from different cancers, alone or in combination with conventional therapies. Even though there are currently a number of efficient anti-angiogenic drugs, including monoclonal antibodies and kinase inhibitors, the associated toxicity profile and their affordability constraints are prompting researchers to search for a safe and affordable angiostatic agent for cancer treatment. Endostatin is one of the endogenous anti-angiogenic candidates that have been extensively pursued for the treatment of cancer, but even over three decades after its discovery, we have not made much advancement in employing it as an anticancer therapeutic despite of its remarkable anti-angiogenic effect with low toxicity profile. A recombinant human endostatin (rh-Es) variant for non-small cell lung cancer was approved by China in 2006 and has since been used effectively. Several other successful clinical trials related to endostatin for various malignancies are either ongoing or have already been completed with promising results. Thus, in this review, we have provided an overview of existing anti-angiogenic drugs developed for cancer therapy, with a summary of tumour angiogenesis in the context of Endostatin, and clinical status of rh-Es in cancer treatment. Furthermore, we briefly discuss the various strategies to improve endostatin features (poor pharmacokinetic properties) for developing rh-Es as a safe and effective agent for cancer treatment.