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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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21 pages, 2940 KiB  
Review
Proteolysis-Targeting Chimera (PROTAC) Delivery into the Brain across the Blood-Brain Barrier
by Toshihiko Tashima
Antibodies 2023, 12(3), 43; https://doi.org/10.3390/antib12030043 - 26 Jun 2023
Cited by 4 | Viewed by 4597
Abstract
Drug development for neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease has challenging difficulties due to the pharmacokinetic impermeability based on the blood-brain barrier (BBB) as well as the blurriness of pharmacodynamic targets based on their unclarified pathogenesis and complicated [...] Read more.
Drug development for neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease has challenging difficulties due to the pharmacokinetic impermeability based on the blood-brain barrier (BBB) as well as the blurriness of pharmacodynamic targets based on their unclarified pathogenesis and complicated progression mechanisms. Thus, in order to produce innovative central nervous system (CNS) agents for patients suffering from CNS diseases, effective, selective delivery of CNS agents into the brain across the BBB should be developed. Currently, proteolysis-targeting chimeras (PROTACs) attract rising attention as a new modality to degrade arbitrary intracellular proteins by the ubiquitin-proteasome system. The internalizations of peptide-based PROTACs by cell-penetrating peptides and that of small molecule-based PROTACs through passive diffusion lack cell selectivity. Therefore, these approaches may bring off-target side effects due to wrong distribution. Furthermore, efflux transporters such as multiple drug resistance 1 (MDR1) expressed at the BBB might interrupt the entry of small molecule-based PROTACs into the brain. Nonetheless, intelligent delivery using machinery systems to absorb the nutrition into the brain for homeostasis, such as carrier-mediated transport (CMT) or receptor-mediated transcytosis (RMT), can be established. PROTACs with N-containing groups that are recognized by the proton-coupled organic cation antiporter might cross the BBB through CMT. PROTAC-antibody conjugates (PACs) might cross the BBB through RMT. Subsequently, such small molecule-based PROTACs released in the brain interstitial fluid would be transported into cells such as neurons through passive diffusion and then demonstrate arbitrary protein degradation. In this review, I introduce the potential and advantages of PROTAC delivery into the brain across the BBB through CMT or RMT using PACs in a non-invasive way. Full article
(This article belongs to the Special Issue Antibodies: 10th Anniversary)
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13 pages, 623 KiB  
Review
The Role of Bispecific Antibodies in Relapsed Refractory Multiple Myeloma: A Systematic Review
by Razwana Khanam, Omer S. Ashruf, Syed Hamza Bin Waqar, Zunairah Shah, Saba Batool, Rameesha Mehreen, Pranali Pachika, Zinath Roksana, Mohammad Ebad Ur Rehman and Faiz Anwer
Antibodies 2023, 12(2), 38; https://doi.org/10.3390/antib12020038 - 29 May 2023
Cited by 4 | Viewed by 3203
Abstract
Multiple myeloma is a heterogeneous clonal malignant plasma cell disorder, which remains incurable despite the therapeutic armamentarium’s evolution. Bispecific antibodies (BsAbs) can bind simultaneously to the CD3 T-cell receptor and tumor antigen of myeloma cells, causing cell lysis. This systematic review of phase [...] Read more.
Multiple myeloma is a heterogeneous clonal malignant plasma cell disorder, which remains incurable despite the therapeutic armamentarium’s evolution. Bispecific antibodies (BsAbs) can bind simultaneously to the CD3 T-cell receptor and tumor antigen of myeloma cells, causing cell lysis. This systematic review of phase I/II/III clinical trials aimed to analyze the efficacy and safety of BsAbs in relapsed refractory multiple myeloma (RRMM). A thorough literature search was performed using PubMed, Cochrane Library, EMBASE, and major conference abstracts. A total of 18 phase I/II/III studies, including 1283 patients, met the inclusion criteria. Among the B-cell maturation antigen (BCMA)-targeting agents across 13 studies, the overall response rate (ORR) ranged between 25% and 100%, with complete response/stringent complete response (CR/sCR) between 7 and 38%, very good partial response (VGPR) between 5 and 92%, and partial response (PR) between 5 and 14%. Among the non-BCMA-targeting agents across five studies, the ORR ranged between 60 and 100%, with CR/sCR seen in 19–63%, and VGPR in 21–65%. The common adverse events were cytokine release syndrome (17–82%), anemia (5–52%), neutropenia (12–75%), and thrombocytopenia (14–42%). BsAbs have shown promising efficacy against RRMM cohorts with a good safety profile. Upcoming phase II/III trials are much awaited, along with the study of other agents in concert with BsAbs to gauge response. Full article
(This article belongs to the Special Issue Novel Strategies and Technologies for the Development of Tumor-Specific Antibodies)
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9 pages, 985 KiB  
Communication
Detection of SARS-CoV-2 Antibodies: Comparison of Enzyme Immunoassay, Surrogate Neutralization and Virus Neutralization Test
by Tatjana Vilibic-Cavlek, Maja Bogdanic, Ema Borko, Zeljka Hruskar, Denis Zilic, Thomas Ferenc, Irena Tabain, Ljubo Barbic, Mateja Vujica Ferenc, Ivana Ferencak and Vladimir Stevanovic
Antibodies 2023, 12(2), 35; https://doi.org/10.3390/antib12020035 - 10 May 2023
Cited by 3 | Viewed by 1734
Abstract
Background: Since sensitivity and specificity vary widely between tests, SARS-CoV-2 serology results should be interpreted with caution. Methods: The study included serum samples from patients who had recovered from COVID-19 (n = 71), individuals vaccinated against SARS-CoV-2 (n = 84), and [...] Read more.
Background: Since sensitivity and specificity vary widely between tests, SARS-CoV-2 serology results should be interpreted with caution. Methods: The study included serum samples from patients who had recovered from COVID-19 (n = 71), individuals vaccinated against SARS-CoV-2 (n = 84), and asymptomatic individuals (n = 33). All samples were tested for the presence of binding antibodies (enzyme immunoassay; EIA), neutralizing (NT) antibodies (virus neutralization test; VNT), and surrogate NT (sNT) antibodies (surrogate virus neutralization test; sVNT) of SARS-CoV-2. Results: SARS-CoV-2-binding antibodies were detected in 71 (100%) COVID-19 patients, 77 (91.6%) vaccinated individuals, and 4 (12.1%) control subjects. Among EIA-positive samples, VNT was positive (titer ≥ 8) in 100% of COVID-19 patients and 63 (75.0%) of the vaccinated individuals, while sVNT was positive (>30% inhibition) in 62 (87.3%) patients and 59 (70.2%) vaccinated individuals. The analysis of antibody levels showed a significant moderate positive correlation between EIA and VNT, a moderate positive correlation between EIA and sVNT, and a strong positive correlation between VNT and sVNT. The proportion of positive sVNT detection rate was associated with VNT titer. The lowest positivity (72.4%/70.8%) was detected in samples with low NT titers (8/16) and increased progressively from 88.2% in samples with titer 32 to 100% in samples with titer 256. Conclusions: sVNT appeared to be a reliable method for the assessment COVID-19 serology in patients with high antibody levels, while false-negative results were frequently observed in patients with low NT titers. Full article
(This article belongs to the Special Issue SARS-CoV-2: Immune Response Elicited by Infection or Vaccination)
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16 pages, 1239 KiB  
Review
CCR6 as a Potential Target for Therapeutic Antibodies for the Treatment of Inflammatory Diseases
by Sara Gómez-Melero and Javier Caballero-Villarraso
Antibodies 2023, 12(2), 30; https://doi.org/10.3390/antib12020030 - 20 Apr 2023
Cited by 4 | Viewed by 4043
Abstract
The CC chemokine receptor 6 (CCR6) is a G protein-coupled receptor (GPCR) involved in a wide range of biological processes. When CCR6 binds to its sole ligand CCL20, a signaling network is produced. This pathway is implicated in mechanisms related to many diseases, [...] Read more.
The CC chemokine receptor 6 (CCR6) is a G protein-coupled receptor (GPCR) involved in a wide range of biological processes. When CCR6 binds to its sole ligand CCL20, a signaling network is produced. This pathway is implicated in mechanisms related to many diseases, such as cancer, psoriasis, multiple sclerosis, HIV infection or rheumatoid arthritis. The CCR6/CCL20 axis plays a fundamental role in immune homeostasis and activation. Th17 cells express the CCR6 receptor and inflammatory cytokines, including IL-17, IL-21 and IL-22, which are involved in the spread of inflammatory response. The CCL20/CCR6 mechanism plays a crucial role in the recruitment of these pro-inflammatory cells to local tissues. To date, there are no drugs against CCR6 approved, and the development of small molecules against CCR6 is complicated due to the difficulty in screenings. This review highlights the potential as a therapeutic target of the CCR6 receptor in numerous diseases and the importance of the development of antibodies against CCR6 that could be a promising alternative to small molecules in the treatment of CCR6/CCL20 axis-related pathologies. Full article
(This article belongs to the Special Issue Antibodies: 10th Anniversary)
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19 pages, 1303 KiB  
Review
New Insights into Pathogenesis and Treatment of ANCA-Associated Vasculitis: Autoantibodies and Beyond
by Marino Paroli, Chiara Gioia and Daniele Accapezzato
Antibodies 2023, 12(1), 25; https://doi.org/10.3390/antib12010025 - 21 Mar 2023
Cited by 4 | Viewed by 5762
Abstract
Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a group of rare systemic diseases affecting small-caliber vessels. The damage caused by AAV mainly involves the lung and kidneys. AAV includes three different types: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis [...] Read more.
Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a group of rare systemic diseases affecting small-caliber vessels. The damage caused by AAV mainly involves the lung and kidneys. AAV includes three different types: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Although the different phenotypic forms of AAV share common features, recent studies have shown that there are significant differences in terms of pathogenetic mechanisms involving both the adaptive and innate immune systems. Advances in our understanding of pathogenesis have enabled the development of immuno-targeted therapies. This review illustrates the characteristics of the various forms of AAV and the new therapies available for this disease that can have lethal consequences if left untreated. Full article
(This article belongs to the Special Issue Autoimmune and Inflammatory Rheumatic Diseases: Potential Biomarkers, Antibodies Response and New Therapies)
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13 pages, 2577 KiB  
Review
Intracellular Antibodies for Drug Discovery and as Drugs of the Future
by T. H. Rabbitts
Antibodies 2023, 12(1), 24; https://doi.org/10.3390/antib12010024 - 16 Mar 2023
Cited by 2 | Viewed by 3461
Abstract
The application of antibodies in cells was first shown in the early 1990s, and subsequently, the field of intracellular antibodies has expanded to encompass antibody fragments and their use in target validation and as engineered molecules that can be fused to moieties (referred [...] Read more.
The application of antibodies in cells was first shown in the early 1990s, and subsequently, the field of intracellular antibodies has expanded to encompass antibody fragments and their use in target validation and as engineered molecules that can be fused to moieties (referred to as warheads) to replace the Fc effector region of a whole immunoglobulin to elicit intracellular responses, such as cell death pathways or protein degradation. These various forms of intracellular antibodies have largely been used as research tools to investigate function within cells by perturbing protein activity. New applications of such molecules are on the horizon, namely their use as drugs per se and as templates for small-molecule drug discovery. The former is a potential new pharmacology that could harness the power and flexibility of molecular biology to generate new classes of drugs (herein referred to as macrodrugs when used in the context of disease control). Delivery of engineered intracellular antibodies, and other antigen-binding macromolecules formats, into cells to produce a therapeutic effect could be applied to any therapeutic area where regulation, degradation or other kinds of manipulation of target proteins can produce a therapeutic effect. Further, employing single-domain antibody fragments as competitors in small-molecule screening has been shown to enable identification of drug hits from diverse chemical libraries. Compounds selected in this way can mimic the effects of the intracellular antibodies that have been used for target validation. The capability of intracellular antibodies to discriminate between closely related proteins lends a new dimension to drug screening and drug development. Full article
(This article belongs to the Special Issue Antibody Drug and Target Discovery for Cancer Therapies)
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24 pages, 1399 KiB  
Review
Intravenous Immunoglobulins as Immunomodulators in Autoimmune Diseases and Reproductive Medicine
by Tsvetelina Velikova, Metodija Sekulovski, Simona Bogdanova, Georgi Vasilev, Monika Peshevska-Sekulovska, Dimitrina Miteva and Tsvetoslav Georgiev
Antibodies 2023, 12(1), 20; https://doi.org/10.3390/antib12010020 - 02 Mar 2023
Cited by 6 | Viewed by 4481
Abstract
Intravenous administration of immunoglobulins has been routinely used for more than 60 years in clinical practice, developed initially as replacement therapy in immunodeficiency disorders. Today, the use of intravenous immunoglobulins (IVIGs) is embedded in the modern algorithms for the management of a few [...] Read more.
Intravenous administration of immunoglobulins has been routinely used for more than 60 years in clinical practice, developed initially as replacement therapy in immunodeficiency disorders. Today, the use of intravenous immunoglobulins (IVIGs) is embedded in the modern algorithms for the management of a few diseases, while in most cases, their application is off-label and thus different from their registered therapeutic indications according to the summary of product characteristics. In this review, we present the state-of-the-art use of IVIGs in various autoimmune conditions and immune-mediated disorders associated with reproductive failure, as approved therapy, based on indications or off-label. IVIGs are often an alternative to other treatments, and the administration of IVIGs continues to expand as data accumulate. Additionally, new insights into the pathophysiology of immune-mediated disorders have been gained. Therefore, the need for immunomodulation has increased, where IVIG therapy represents an option for stimulating, inhibiting and regulating various immune processes. Full article
(This article belongs to the Special Issue Antibodies: 10th Anniversary)
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14 pages, 1769 KiB  
Review
Serological Cross-Reactivity in Zoonotic Flaviviral Infections of Medical Importance
by Priscilla Gomes da Silva, José Augusto Seixas dos Reis, Marcio Nogueira Rodrigues, Quézia da Silva Ardaya and João Rodrigo Mesquita
Antibodies 2023, 12(1), 18; https://doi.org/10.3390/antib12010018 - 24 Feb 2023
Cited by 5 | Viewed by 2557
Abstract
Flaviviruses are enveloped RNA viruses from the family Flaviviridae that comprise many important human pathogenic arboviruses such as Yellow Fever, Dengue, and Zika viruses. Because they belong to the same genus, these viruses show sequence and structural homology among them, which results in [...] Read more.
Flaviviruses are enveloped RNA viruses from the family Flaviviridae that comprise many important human pathogenic arboviruses such as Yellow Fever, Dengue, and Zika viruses. Because they belong to the same genus, these viruses show sequence and structural homology among them, which results in serological cross-reactivity. Upon infection, the immune system produces both species-specific and cross-reactive antibodies, and depending on the virus, in a successive flavivirus infection, cross-reactive antibodies either enhance protection or exacerbate the disease—the latter usually due to antibody-dependent enhancement. These antigenic relationships between different flaviviruses that lead to serological cross-reactivity make them difficult to be identified through serological methods, especially when it comes to successive flavivirus infections. We present here an overview of the main structural, epidemiological, and immunological aspects of flaviviruses, highlighting the role of neutralizing antibodies in fighting viral infections and in the “original antigenic sin” problem. Finally, we draw attention to the importance of developing a rapid serological diagnostic test for flaviviruses with high sensitivity and specificity, especially when considering that cross-reactive immunity can influence the outcome of these infections. Full article
(This article belongs to the Section Humoral Immunity)
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19 pages, 6552 KiB  
Review
Non-Affinity Purification of Antibodies
by Tsutomu Arakawa, Yui Tomioka, Masataka Nakagawa, Chiaki Sakuma, Yasunori Kurosawa, Daisuke Ejima, Kouhei Tsumoto and Teruo Akuta
Antibodies 2023, 12(1), 15; https://doi.org/10.3390/antib12010015 - 13 Feb 2023
Cited by 5 | Viewed by 4560
Abstract
Currently, purification of antibodies is mainly carried out using a platform technology composed primarily of Protein A chromatography as a capture step, regardless of the scale. However, Protein A chromatography has a number of drawbacks, which are summarized in this review. As an [...] Read more.
Currently, purification of antibodies is mainly carried out using a platform technology composed primarily of Protein A chromatography as a capture step, regardless of the scale. However, Protein A chromatography has a number of drawbacks, which are summarized in this review. As an alternative, we propose a simple small-scale purification protocol without Protein A that uses novel agarose native gel electrophoresis and protein extraction. For large-scale antibody purification, we suggest mixed-mode chromatography that can in part mimic the properties of Protein A resin, focusing on 4-Mercapto-ethyl-pyridine (MEP) column chromatography. Full article
(This article belongs to the Special Issue Antibodies: 10th Anniversary)
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16 pages, 1299 KiB  
Review
A Review of the Currently Available Antibody Therapy for the Treatment of Coronavirus Disease 2019 (COVID-19)
by Kristin Widyasari and Jinnam Kim
Antibodies 2023, 12(1), 5; https://doi.org/10.3390/antib12010005 - 11 Jan 2023
Cited by 13 | Viewed by 3377
Abstract
Monoclonal antibodies are a promising treatment for COVID-19. However, the emergence of SARS-CoV-2 variants raised concerns about these therapies’ efficacy and long-term viability. Studies reported several antibodies, that received authorization for COVID-19 treatment, are not effective against new variants or subvariants of SARS-CoV-2, [...] Read more.
Monoclonal antibodies are a promising treatment for COVID-19. However, the emergence of SARS-CoV-2 variants raised concerns about these therapies’ efficacy and long-term viability. Studies reported several antibodies, that received authorization for COVID-19 treatment, are not effective against new variants or subvariants of SARS-CoV-2, hence their distribution has to be paused. Here, the authors reviewed the status of the currently available monoclonal antibodies for COVID-19 treatment, their potential as a therapeutic agent, and the challenges ahead. To address these issues, the authors presented general information on SARS-CoV-2 and how monoclonal antibodies work against SARS-CoV-2. The authors then focus on the antibodies that have been deployed for COVID-19 treatment and their current status, as well as the evidence supporting their potential as an early intervention against COVID-19. Lastly, the authors discussed some leading obstacles that hinder the development and administration of monoclonal antibodies for the treatment of COVID-19. Full article
(This article belongs to the Special Issue The Role of Antibodies in SARS-CoV-2 Infection)
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11 pages, 893 KiB  
Review
TLR7 and IgM: Dangerous Partners in Autoimmunity
by Timm Amendt and Philipp Yu
Antibodies 2023, 12(1), 4; https://doi.org/10.3390/antib12010004 - 06 Jan 2023
Cited by 2 | Viewed by 3478
Abstract
The B cell antigen receptor (BCR)-repertoire is capable of recognizing a nearly unlimited number of antigens. Inevitably, the random nature of antibody gene segment rearrangement, needed in order to provide mature B cells, will generate autoreactive specificities. Once tolerance mechanisms fail to block [...] Read more.
The B cell antigen receptor (BCR)-repertoire is capable of recognizing a nearly unlimited number of antigens. Inevitably, the random nature of antibody gene segment rearrangement, needed in order to provide mature B cells, will generate autoreactive specificities. Once tolerance mechanisms fail to block the activation and differentiation of autoreactive B cells, harmful autoantibodies may get secreted establishing autoimmune diseases. Besides the hallmark of autoimmunity, namely IgG autoantibodies, IgM autoantibodies are also found in many autoimmune diseases. In addition to pathogenic functions of secreted IgM the IgM-BCR expressing B cell might be the initial check-point where, in conjunction with innate receptor signals, B cell mediated autoimmunity starts it fateful course. Recently, pentameric IgM autoantibodies have been shown to contribute significantly to the pathogenesis of various autoimmune diseases, such as rheumatoid arthritis (RA), autoimmune hemolytic anemia (AIHA), pemphigus or autoimmune neuropathy. Further, recent studies suggest differences in the recognition of autoantigen by IgG and IgM autoantibodies, or propose a central role of anti-ACE2-IgM autoantibodies in severe COVID-19. However, exact mechanisms still remain to be uncovered in detail. This article focuses on summarizing recent findings regarding the importance of autoreactive IgM in establishing autoimmune diseases. Full article
(This article belongs to the Section Humoral Immunity)
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13 pages, 1115 KiB  
Review
Specific Autoantibodies and Microvascular Damage Progression Assessed by Nailfold Videocapillaroscopy in Systemic Sclerosis: Are There Peculiar Associations? An Update
by Elvis Hysa, Rosanna Campitiello, Silvia Sammorì, Emanuele Gotelli, Andrea Cere, Giampaola Pesce, Carmen Pizzorni, Sabrina Paolino, Alberto Sulli, Vanessa Smith and Maurizio Cutolo
Antibodies 2023, 12(1), 3; https://doi.org/10.3390/antib12010003 - 04 Jan 2023
Cited by 3 | Viewed by 2398
Abstract
Background: Specific autoantibodies and nailfold videocapillaroscopy (NVC) findings are serum and morphological diagnostic hallmarks of systemic sclerosis (SSc) as well as useful biomarkers which stratify the microvascular progression and prognosis of patients. Methods: The aim of our narrative review is to provide an [...] Read more.
Background: Specific autoantibodies and nailfold videocapillaroscopy (NVC) findings are serum and morphological diagnostic hallmarks of systemic sclerosis (SSc) as well as useful biomarkers which stratify the microvascular progression and prognosis of patients. Methods: The aim of our narrative review is to provide an update and overview of the link between SSc-related autoantibodies, used in clinical practice, and microvascular damage, evaluated by NVC, by exploring the interaction between these players in published studies. A narrative review was conducted by searching relevant keywords related to this field in Pubmed, Medline and EULAR/ACR conference abstracts with a focus on the findings published in the last 5 years. Results: Our search yielded 13 clinical studies and 10 pre-clinical studies. Most of the clinical studies (8/13, 61.5%) reported a significant association between SSc-related autoantibodies and NVC patterns: more specifically anti-centromere autoantibodies (ACA) were associated more often with an “Early” NVC pattern, whereas anti-topoisomerase autoantibodies (ATA) more frequently showed an “Active” or “Late” NVC pattern. Five studies, instead, did not find a significant association between specific autoantibodies and NVC findings. Among the pre-clinical studies, SSc-related autoantibodies showed different mechanisms of damage towards both endothelial cells, fibroblasts and smooth muscle vascular cells. Conclusions: The clinical and laboratory evidence on SSc-related autoantibodies and microvascular damage shows that these players are interconnected. Further clinical and demographic factors (e.g., age, sex, disease duration, treatment and comorbidities) might play an additional role in the SSc-related microvascular injury whose progression appears to be complex and multifactorial. Full article
(This article belongs to the Special Issue New, Old, and Shared Antibody Specificities in Autoimmune Diseases)
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24 pages, 3262 KiB  
Review
Delivery of Drugs into Cancer Cells Using Antibody–Drug Conjugates Based on Receptor-Mediated Endocytosis and the Enhanced Permeability and Retention Effect
by Toshihiko Tashima
Antibodies 2022, 11(4), 78; https://doi.org/10.3390/antib11040078 - 19 Dec 2022
Cited by 7 | Viewed by 3789
Abstract
Innumerable people worldwide die of cancer every year, although pharmaceutical therapy has actualized many benefits in human health. For background, anti-cancer drug development is difficult due to the multifactorial pathogenesis and complicated pathology of cancers. Cancer cells excrete hydrophobic low-molecular anti-cancer drugs by [...] Read more.
Innumerable people worldwide die of cancer every year, although pharmaceutical therapy has actualized many benefits in human health. For background, anti-cancer drug development is difficult due to the multifactorial pathogenesis and complicated pathology of cancers. Cancer cells excrete hydrophobic low-molecular anti-cancer drugs by overexpressed efflux transporters such as multiple drug resistance 1 (MDR1) at the apical membrane. Mutation-driven drug resistance is also developed in cancer. Moreover, the poor distribution of drug to cancer cells is a serious problem, because patients suffer from off-target side effects. Thus, highly selective and effective drug delivery into solid cancer cells across the membrane should be established. It is known that substances (10–100 nm in diameter) such as monoclonal antibodies (mAbs) (approximately 14.2 nm in diameter) or nanoparticles spontaneously gather in solid tumor stroma or parenchyma through the capillary endothelial fenestration, ranging from 200–2000 nm, in neovasculatures due to the enhanced permeability and retention (EPR) effect. Furthermore, cancer antigens, such as HER2, Nectin-4, or TROP2, highly selectively expressed on the surface of cancer cells act as a receptor for receptor-mediated endocytosis (RME) using mAbs against such antigens. Thus, antibody–drug conjugates (ADCs) are promising anti-cancer pharmaceutical agents that fulfill accurate distribution due to the EPR effect and due to antibody–antigen binding and membrane permeability owing to RME. In this review, I introduce the implementation and possibility of highly selective anti-cancer drug delivery into solid cancer cells based on the EPR effect and RME using anti-cancer antigens ADCs with payloads through suitable linkers. Full article
(This article belongs to the Special Issue Targeting Tumor Cells with Antibodies Enhances Anti-Tumor Immunity)
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25 pages, 480 KiB  
Review
Risk-Based Control Strategies of Recombinant Monoclonal Antibody Charge Variants
by Alain Beck, Christine Nowak, Deborah Meshulam, Kristina Reynolds, David Chen, Dennis B. Pacardo, Samantha B. Nicholls, Gregory J. Carven, Zhenyu Gu, Jing Fang, Dongdong Wang, Amit Katiyar, Tao Xiang and Hongcheng Liu
Antibodies 2022, 11(4), 73; https://doi.org/10.3390/antib11040073 - 20 Nov 2022
Cited by 11 | Viewed by 5649
Abstract
Since the first approval of the anti-CD3 recombinant monoclonal antibody (mAb), muromonab-CD3, a mouse antibody for the prevention of transplant rejection, by the US Food and Drug Administration (FDA) in 1986, mAb therapeutics have become increasingly important to medical care. A wealth of [...] Read more.
Since the first approval of the anti-CD3 recombinant monoclonal antibody (mAb), muromonab-CD3, a mouse antibody for the prevention of transplant rejection, by the US Food and Drug Administration (FDA) in 1986, mAb therapeutics have become increasingly important to medical care. A wealth of information about mAbs regarding their structure, stability, post-translation modifications, and the relationship between modification and function has been reported. Yet, substantial resources are still required throughout development and commercialization to have appropriate control strategies to maintain consistent product quality, safety, and efficacy. A typical feature of mAbs is charge heterogeneity, which stems from a variety of modifications, including modifications that are common to many mAbs or unique to a specific molecule or process. Charge heterogeneity is highly sensitive to process changes and thus a good indicator of a robust process. It is a high-risk quality attribute that could potentially fail the specification and comparability required for batch disposition. Failure to meet product specifications or comparability can substantially affect clinical development timelines. To mitigate these risks, the general rule is to maintain a comparable charge profile when process changes are inevitably introduced during development and even after commercialization. Otherwise, new peaks or varied levels of acidic and basic species must be justified based on scientific knowledge and clinical experience for a specific molecule. Here, we summarize the current understanding of mAb charge variants and outline risk-based control strategies to support process development and ultimately commercialization. Full article
16 pages, 2251 KiB  
Review
Structural Investigation of Therapeutic Antibodies Using Hydroxyl Radical Protein Footprinting Methods
by Corie Y. Ralston and Joshua S. Sharp
Antibodies 2022, 11(4), 71; https://doi.org/10.3390/antib11040071 - 14 Nov 2022
Cited by 7 | Viewed by 2481
Abstract
Commercial monoclonal antibodies are growing and important components of modern therapies against a multitude of human diseases. Well-known high-resolution structural methods such as protein crystallography are often used to characterize antibody structures and to determine paratope and/or epitope binding regions in order to [...] Read more.
Commercial monoclonal antibodies are growing and important components of modern therapies against a multitude of human diseases. Well-known high-resolution structural methods such as protein crystallography are often used to characterize antibody structures and to determine paratope and/or epitope binding regions in order to refine antibody design. However, many standard structural techniques require specialized sample preparation that may perturb antibody structure or require high concentrations or other conditions that are far from the conditions conducive to the accurate determination of antigen binding or kinetics. We describe here in this minireview the relatively new method of hydroxyl radical protein footprinting, a solution-state method that can provide structural and kinetic information on antibodies or antibody–antigen interactions useful for therapeutic antibody design. We provide a brief history of hydroxyl radical footprinting, examples of current implementations, and recent advances in throughput and accessibility. Full article
(This article belongs to the Special Issue Higher Order Structure Characterization of Therapeutic Antibodies-Second Volume)
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8 pages, 516 KiB  
Article
Neutralizing and Total/IgG Spike Antibody Responses Following Homologous CoronaVac vs. BNT162b2 Vaccination Up to 90 Days Post-Booster
by Chin Shern Lau, John Thundyil, May Lin Helen Oh, Soon Kieng Phua, Ya Li Liang, Yanfeng Li, Jianxin Huo, Yuhan Huang, Biyan Zhang, Shengli Xu and Tar Choon Aw
Antibodies 2022, 11(4), 70; https://doi.org/10.3390/antib11040070 - 08 Nov 2022
Cited by 4 | Viewed by 1790
Abstract
Introduction: We documented the total spike antibody (S-Ab), IgG S-Ab and neutralizing antibody (N-Ab) responses of BNT162b2/CoronaVac vaccinees up to 90 days post-booster dose. Methods: We included 32 homologous regimen CoronaVac vaccinees and 136 BNT162b2 mRNA vaccinees. We tested their total S-Ab (Roche), [...] Read more.
Introduction: We documented the total spike antibody (S-Ab), IgG S-Ab and neutralizing antibody (N-Ab) responses of BNT162b2/CoronaVac vaccinees up to 90 days post-booster dose. Methods: We included 32 homologous regimen CoronaVac vaccinees and 136 BNT162b2 mRNA vaccinees. We tested their total S-Ab (Roche), IgG (Abbott) and N-Ab (Snibe) levels at set time points from January 2021 to April 2022. All subjects were deemed to be COVID-19-naïve either via clinical history (CoronaVac vaccinees) or nucleocapsid antibody testing (BNT162b2 vaccinees). Results: All antibodies peaked 20–30 days post-inoculation. In BNT162b2 vaccinees, all post-booster antibodies were significantly higher than second-dose peaks. In CoronaVac vaccinees, IgG showed no significant differences between peak third-/second-dose titers (difference of 56.0 BAU/mL, 95% CI of −17.1 to 129, p = 0.0894). The post-vaccination titers of all antibodies in BNT162b2 vaccinees were significantly higher than those in CoronaVac vaccinees at all time points. Post-booster, all antibodies declined in 90 days; the final total/IgG/N-Ab titers were 7536 BAU/mL, 1276 BAU/mL and 12.5 μg/mL in BNT162b2 vaccinees and 646 BAU/mL, 62.4 BAU/mL and 0.44 μg/mL in CoronaVac vaccinees. Conclusion: The mRNA vaccine generated more robust total S-Ab, IgG and N-Ab responses after the second and third vaccinations. Full article
(This article belongs to the Special Issue The Role of Antibodies in SARS-CoV-2 Infection)
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14 pages, 2653 KiB  
Article
Rational Design and In Vivo Characterization of mRNA-Encoded Broadly Neutralizing Antibody Combinations against HIV-1
by Elisabeth Narayanan, Samantha Falcone, Sayda M. Elbashir, Husain Attarwala, Kimberly Hassett, Michael S. Seaman, Andrea Carfi and Sunny Himansu
Antibodies 2022, 11(4), 67; https://doi.org/10.3390/antib11040067 - 24 Oct 2022
Cited by 5 | Viewed by 3420
Abstract
Monoclonal antibodies have been used successfully as recombinant protein therapy; however, for HIV, multiple broadly neutralizing antibodies may be necessary. We used the mRNA-LNP platform for in vivo co-expression of 3 broadly neutralizing antibodies, PGDM1400, PGT121, and N6, directed against the HIV-1 envelope [...] Read more.
Monoclonal antibodies have been used successfully as recombinant protein therapy; however, for HIV, multiple broadly neutralizing antibodies may be necessary. We used the mRNA-LNP platform for in vivo co-expression of 3 broadly neutralizing antibodies, PGDM1400, PGT121, and N6, directed against the HIV-1 envelope protein. mRNA-encoded HIV-1 antibodies were engineered as single-chain Fc (scFv-Fc) to overcome heavy- and light-chain mismatch. In vitro neutralization breadth and potency of the constructs were compared to their parental IgG form. We assessed the ability of these scFv-Fcs to be expressed individually and in combination in vivo, and neutralization and pharmacokinetics were compared to the corresponding full-length IgGs. Single-chain PGDM1400 and PGT121 exhibited neutralization potency comparable to parental IgG, achieving peak systemic concentrations ≥ 30.81 μg/mL in mice; full-length N6 IgG achieved a peak concentration of 974 μg/mL, but did not tolerate single-chain conversion. The mRNA combination encoding full-length N6 IgG and single-chain PGDM1400 and PGT121 was efficiently expressed in mice, achieving high systemic concentration and desired neutralization potency. Analysis of mice sera demonstrated each antibody contributed towards neutralization of multiple HIV-1 pseudoviruses. Together, these data show that the mRNA-LNP platform provides a promising approach for antibody-based HIV treatment and is well-suited for development of combination therapeutics. Full article
(This article belongs to the Section Antibody-Based Therapeutics)
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45 pages, 4126 KiB  
Article
IMGT® Nomenclature of Engineered IGHG Variants Involved in Antibody Effector Properties and Formats
by Marie-Paule Lefranc and Gérard Lefranc
Antibodies 2022, 11(4), 65; https://doi.org/10.3390/antib11040065 - 18 Oct 2022
Cited by 3 | Viewed by 2891
Abstract
The constant region of the immunoglobulin (IG) or antibody heavy gamma chain is frequently engineered to modify the effector properties of the therapeutic monoclonal antibodies. These variants are classified in regards to their effects on effector functions, antibody-dependent cytotoxicity (ADCC), antibody-dependent phagocytosis (ADCP), [...] Read more.
The constant region of the immunoglobulin (IG) or antibody heavy gamma chain is frequently engineered to modify the effector properties of the therapeutic monoclonal antibodies. These variants are classified in regards to their effects on effector functions, antibody-dependent cytotoxicity (ADCC), antibody-dependent phagocytosis (ADCP), complement-dependent cytotoxicity (CDC) enhancement or reduction, B cell inhibition by the coengagement of antigen and FcγR on the same cell, on half-life increase, and/or on structure such as prevention of IgG4 half-IG exchange, hexamerisation, knobs-into-holes and the heteropairing H-H of bispecific antibodies, absence of disulfide bridge inter H-L, absence of glycosylation site, and site-specific drug attachment engineered cysteine. The IMGT engineered variant identifier is comprised of the species and gene name (and eventually allele), the letter ‘v’ followed by a number (assigned chronologically), and for each concerned domain (e.g, CH1, h, CH2 and CH3), the novel AA (single letter abbreviation) and IMGT position according to the IMGT unique numbering for the C-domain and between parentheses, the Eu numbering. IMGT engineered variants are described with detailed amino acid changes, visualized in motifs based on the IMGT numbering bridging genes, sequences, and structures for higher order description. Full article
(This article belongs to the Special Issue Higher Order Structure Characterization of Therapeutic Antibodies-Second Volume)
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9 pages, 869 KiB  
Review
IgY Antibodies as Biotherapeutics in Biomedicine
by Diana León-Núñez, María Fernanda Vizcaíno-López, Magdalena Escorcia, Dolores Correa, Elizabeth Pérez-Hernández and Fernando Gómez-Chávez
Antibodies 2022, 11(4), 62; https://doi.org/10.3390/antib11040062 - 29 Sep 2022
Cited by 8 | Viewed by 4796
Abstract
Since the discovery of antibodies by Emil Von Behring and Shibasaburo Kitasato during the 19th century, their potential for use as biotechnological reagents has been exploited in different fields, such as basic and applied research, diagnosis, and the treatment of multiple diseases. Antibodies [...] Read more.
Since the discovery of antibodies by Emil Von Behring and Shibasaburo Kitasato during the 19th century, their potential for use as biotechnological reagents has been exploited in different fields, such as basic and applied research, diagnosis, and the treatment of multiple diseases. Antibodies are relatively easy to obtain from any species with an adaptive immune system, but birds are animals characterized by relatively easy care and maintenance. In addition, the antibodies they produce can be purified from the egg yolk, allowing a system for obtaining them without performing invasive practices, which favors the three “rs” of animal care in experimentation, i.e., replacing, reducing, and refining. In this work, we carry out a brief descriptive review of the most outstanding characteristics of so-called “IgY technology” and the use of IgY antibodies from birds for basic experimentation, diagnosis, and treatment of human beings and animals. Full article
(This article belongs to the Section Antibody-Based Therapeutics)
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11 pages, 556 KiB  
Article
Investigation of Possible Factors Influencing the Neutralizing Anti-SARS-CoV-2 Antibody Titer after Six Months from the Second Vaccination Dose in a Sample of Italian Nursing Home Personnel
by Alberto Modenese, Stefania Paduano, Rossana Bellucci, Simona Marchetti, Fulvio Bruno, Pietro Grazioli, Roberto Vivoli, Fabriziomaria Gobba and Annalisa Bargellini
Antibodies 2022, 11(3), 59; https://doi.org/10.3390/antib11030059 - 19 Sep 2022
Cited by 4 | Viewed by 1969
Abstract
The titer of the anti-SARS-CoV-2 antibodies produced after vaccination shows a relevant decay over time, as demonstrated in several studies. However, less is known on the possible factors affecting the entity of this decay. The aim of this study is to analyze a [...] Read more.
The titer of the anti-SARS-CoV-2 antibodies produced after vaccination shows a relevant decay over time, as demonstrated in several studies. However, less is known on the possible factors affecting the entity of this decay. The aim of this study is to analyze a group of individual factors which are possibly associated with anti-SARS-CoV-2 antibody titer decay six months after the second vaccine dose. We report here the results of a follow-up serological analysis and a questionnaire-based evaluation of a sample of workers from an Italian nursing home, vaccinated with two doses of BNT162b2 vaccine in early 2021. The baseline data were collected one month after the vaccine, while in the present analysis we report the data collected six months later. Our data show a relevant decay of the neutralizing antibody titer, even if for all the workers a largely positive response was detected. Moreover, our results demonstrate a possible association between younger age and the absence of previous COVID-19 infection, and a higher decay rate of the anti-SARS-CoV-2 antibodies titer. Full article
(This article belongs to the Special Issue Coronavirus-Targeting Antibodies)
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13 pages, 2187 KiB  
Article
In Vitro and In Vivo Characterization of a Broadly Neutralizing Anti-SARS-CoV-2 Antibody Isolated from a Semi-Immune Phage Display Library
by Edith González-González, Gregorio Carballo-Uicab, Juana Salinas-Trujano, María I. Cortés-Paniagua, Said Vázquez-Leyva, Luis Vallejo-Castillo, Ivette Mendoza-Salazar, Keyla Gómez-Castellano, Sonia M. Pérez-Tapia and Juan C. Almagro
Antibodies 2022, 11(3), 57; https://doi.org/10.3390/antib11030057 - 06 Sep 2022
Cited by 4 | Viewed by 2633
Abstract
Neutralizing antibodies targeting the receptor-binding domain (RBD) of SARS-CoV-2 are among the most promising strategies to prevent and/or treat COVID-19. However, as SARS-CoV-2 has evolved into new variants, most of the neutralizing antibodies authorized by the US FDA and/or EMA to treat COVID-19 [...] Read more.
Neutralizing antibodies targeting the receptor-binding domain (RBD) of SARS-CoV-2 are among the most promising strategies to prevent and/or treat COVID-19. However, as SARS-CoV-2 has evolved into new variants, most of the neutralizing antibodies authorized by the US FDA and/or EMA to treat COVID-19 have shown reduced efficacy or have failed to neutralize the variants of concern (VOCs), particularly B.1.1.529 (Omicron). Previously, we reported the discovery and characterization of antibodies with high affinity for SARS-CoV-2 RBD Wuhan (WT), B.1.617.2 (Delta), and B.1.1.529 (Omicron) strains. One of the antibodies, called IgG-A7, also blocked the interaction of human angiotensin-converting enzyme 2 (hACE2) with the RBDs of the three strains, suggesting it may be a broadly SARS-CoV-2 neutralizing antibody. Herein, we show that IgG-A7 efficiently neutralizes all the three SARS-CoV-2 strains in plaque reduction neutralization tests (PRNTs). In addition, we demonstrate that IgG-A7 fully protects K18-hACE2 transgenic mice infected with SARS-CoV-2 WT. Taken together, our findings indicate that IgG-A7 could be a suitable candidate for development of antibody-based drugs to treat and/or prevent SARS-CoV-2 VOCs infection. Full article
(This article belongs to the Topic Host Response against SARS-CoV-2 Infection: Implications for Diagnosis, Treatment and Vaccine Development)
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25 pages, 1041 KiB  
Review
Alternative Routes of Administration for Therapeutic Antibodies—State of the Art
by Aubin Pitiot, Nathalie Heuzé-Vourc’h and Thomas Sécher
Antibodies 2022, 11(3), 56; https://doi.org/10.3390/antib11030056 - 26 Aug 2022
Cited by 13 | Viewed by 5861
Abstract
Background: For the past two decades, there has been a huge expansion in the development of therapeutic antibodies, with 6 to 10 novel entities approved each year. Around 70% of these Abs are delivered through IV injection, a mode of administration allowing rapid [...] Read more.
Background: For the past two decades, there has been a huge expansion in the development of therapeutic antibodies, with 6 to 10 novel entities approved each year. Around 70% of these Abs are delivered through IV injection, a mode of administration allowing rapid and systemic delivery of the drug. However, according to the evidence presented in the literature, beyond the reduction of invasiveness, a better efficacy can be achieved with local delivery. Consequently, efforts have been made toward the development of innovative methods of administration, and in the formulation and engineering of novel Abs to improve their therapeutic index. Objective: This review presents an overview of the routes of administration used to deliver Abs, different from the IV route, whether approved or in the clinical evaluation stage. We provide a description of the physical and biological fundamentals for each route of administration, highlighting their relevance with examples of clinically-relevant Abs, and discussing their strengths and limitations. Methods: We reviewed and analyzed the current literature, published as of the 1 April 2022 using MEDLINE and EMBASE databases, as well as the FDA and EMA websites. Ongoing trials were identified using clinicaltrials.gov. Publications and data were identified using a list of general keywords. Conclusions: Apart from the most commonly used IV route, topical delivery of Abs has shown clinical successes, improving drug bioavailability and efficacy while reducing side-effects. However, additional research is necessary to understand the consequences of biological barriers associated with local delivery for Ab partitioning, in order to optimize delivery methods and devices, and to adapt Ab formulation to local delivery. Novel modes of administration for Abs might in fine allow a better support to patients, especially in the context of chronic diseases, as well as a reduction of the treatment cost. Full article
(This article belongs to the Special Issue Women's Special Issue Series: Recent Development for Improved Therapeutic Antibodies)
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8 pages, 489 KiB  
Review
Mitochondrial Autoantibodies and the Role of Apoptosis in Pemphigus Vulgaris
by Dana M. Hutchison, Anna-Marie Hosking, Ellen M. Hong and Sergei A. Grando
Antibodies 2022, 11(3), 55; https://doi.org/10.3390/antib11030055 - 25 Aug 2022
Cited by 4 | Viewed by 3360
Abstract
Pemphigus vulgaris (PV) is an IgG autoantibody-mediated, potentially fatal mucocutaneous disease manifested by progressive non-healing erosions and blisters. Beyond acting to inhibit adhesion molecules, PVIgGs elicit a unique process of programmed cell death and detachment of epidermal keratinocytes termed apoptolysis. Mitochondrial damage by [...] Read more.
Pemphigus vulgaris (PV) is an IgG autoantibody-mediated, potentially fatal mucocutaneous disease manifested by progressive non-healing erosions and blisters. Beyond acting to inhibit adhesion molecules, PVIgGs elicit a unique process of programmed cell death and detachment of epidermal keratinocytes termed apoptolysis. Mitochondrial damage by antimitochondrial antibodies (AMA) has proven to be a critical link in this process. AMA act synergistically with other autoantibodies in the pathogenesis of PV. Importantly, absorption of AMA inhibits the ability of PVIgGs to induce blisters. Pharmacologic agents that protect mitochondrial function offer a new targeted approach to treating this severe immunoblistering disease. Full article
(This article belongs to the Special Issue Advances in the Use of Therapeutic Antibodies and Identification of Novel Autoantibodies in Dermatologic Disease)
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12 pages, 588 KiB  
Review
IgG Avidity Test as a Tool for Discrimination between Recent and Distant Toxoplasma gondii Infection—Current Status of Studies
by Lucyna Holec-Gąsior and Karolina Sołowińska
Antibodies 2022, 11(3), 52; https://doi.org/10.3390/antib11030052 - 15 Aug 2022
Cited by 6 | Viewed by 7418
Abstract
Toxoplasma gondii, an obligate intracellular protozoan parasite, is the causative agent of one of the most prevalent zoonoses worldwide. T. gondii infection is extremely important from a medical point of view, especially for pregnant women, newborns with congenital infections, and immunocompromised individuals. [...] Read more.
Toxoplasma gondii, an obligate intracellular protozoan parasite, is the causative agent of one of the most prevalent zoonoses worldwide. T. gondii infection is extremely important from a medical point of view, especially for pregnant women, newborns with congenital infections, and immunocompromised individuals. Thus, an accurate and proper diagnosis of this infection is essential. Among the available diagnostic tests, serology is commonly used. However, traditional serological techniques have certain limitations in evaluating the duration of T. gondii infection, which is problematic, especially for pregnant women. Avidity of T. gondii-specific IgG antibodies seems to be a significant tool for discrimination between recent and distant infections. This article describes the problem of diagnosis of T. gondii infection, with regard to IgG avidity tests. The IgG avidity test is a useful serological indicator of toxoplasmosis, which in many cases can confirm or exclude the active form of the disease. IgG antibodies produced in the recent primary T. gondii infection are of low avidity while IgG antibodies with high avidity are detected in the chronic phase of infection. Furthermore, this paper presents important topics of current research that concern the usage of parasite recombinant antigens that may improve the performance of IgG avidity tests. Full article
(This article belongs to the Section Antibody-Based Diagnostics)
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19 pages, 2152 KiB  
Article
On the Rapid Calculation of Binding Affinities for Antigen and Antibody Design and Affinity Maturation Simulations
by Simone Conti, Edmond Y. Lau and Victor Ovchinnikov
Antibodies 2022, 11(3), 51; https://doi.org/10.3390/antib11030051 - 03 Aug 2022
Cited by 3 | Viewed by 4238
Abstract
The accurate and efficient calculation of protein-protein binding affinities is an essential component in antibody and antigen design and optimization, and in computer modeling of antibody affinity maturation. Such calculations remain challenging despite advances in computer hardware and algorithms, primarily because proteins are [...] Read more.
The accurate and efficient calculation of protein-protein binding affinities is an essential component in antibody and antigen design and optimization, and in computer modeling of antibody affinity maturation. Such calculations remain challenging despite advances in computer hardware and algorithms, primarily because proteins are flexible molecules, and thus, require explicit or implicit incorporation of multiple conformational states into the computational procedure. The astronomical size of the amino acid sequence space further compounds the challenge by requiring predictions to be computed within a short time so that many sequence variants can be tested. In this study, we compare three classes of methods for antibody/antigen (Ab/Ag) binding affinity calculations: (i) a method that relies on the physical separation of the Ab/Ag complex in equilibrium molecular dynamics (MD) simulations, (ii) a collection of 18 scoring functions that act on an ensemble of structures created using homology modeling software, and (iii) methods based on the molecular mechanics-generalized Born surface area (MM-GBSA) energy decomposition, in which the individual contributions of the energy terms are scaled to optimize agreement with the experiment. When applied to a set of 49 antibody mutations in two Ab/HIV gp120 complexes, all of the methods are found to have modest accuracy, with the highest Pearson correlations reaching about 0.6. In particular, the most computationally intensive method, i.e., MD simulation, did not outperform several scoring functions. The optimized energy decomposition methods provided marginally higher accuracy, but at the expense of requiring experimental data for parametrization. Within each method class, we examined the effect of the number of independent computational replicates, i.e., modeled structures or reinitialized MD simulations, on the prediction accuracy. We suggest using about ten modeled structures for scoring methods, and about five simulation replicates for MD simulations as a rule of thumb for obtaining reasonable convergence. We anticipate that our study will be a useful resource for practitioners working to incorporate binding affinity calculations within their protein design and optimization process. Full article
(This article belongs to the Special Issue Computational Discovery of Antibodies)
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20 pages, 11965 KiB  
Review
Therapeutic Potential of Intrabodies for Cancer Immunotherapy: Current Status and Future Directions
by Thomas Böldicke
Antibodies 2022, 11(3), 49; https://doi.org/10.3390/antib11030049 - 18 Jul 2022
Cited by 9 | Viewed by 4289
Abstract
Tumor cells are characterized by overexpressed tumor-associated antigens or mutated neoantigens, which are expressed on the cell surface or intracellularly. One strategy of cancer immunotherapy is to target cell-surface-expressed tumor-associated antigens (TAAs) with therapeutic antibodies. For targeting TAAs or neoantigens, adoptive T-cell therapies [...] Read more.
Tumor cells are characterized by overexpressed tumor-associated antigens or mutated neoantigens, which are expressed on the cell surface or intracellularly. One strategy of cancer immunotherapy is to target cell-surface-expressed tumor-associated antigens (TAAs) with therapeutic antibodies. For targeting TAAs or neoantigens, adoptive T-cell therapies with activated autologous T cells from cancer patients transduced with novel recombinant TCRs or chimeric antigen receptors have been successfully applied. Many TAAs and most neoantigens are expressed in the cytoplasm or nucleus of tumor cells. As alternative to adoptive T-cell therapy, the mRNA of intracellular tumor antigens can be depleted by RNAi, the corresponding genes or proteins deleted by CRISPR-Cas or inactivated by kinase inhibitors or by intrabodies, respectively. Intrabodies are suitable to knockdown TAAs and neoantigens without off-target effects. RNA sequencing and proteome analysis of single tumor cells combined with computational methods is bringing forward the identification of new neoantigens for the selection of anti-cancer intrabodies, which can be easily performed using phage display antibody repertoires. For specifically delivering intrabodies into tumor cells, the usage of new capsid-modified adeno-associated viruses and lipid nanoparticles coupled with specific ligands to cell surface receptors can be used and might bring cancer intrabodies into the clinic. Full article
(This article belongs to the Special Issue Antibody Drug and Target Discovery for Cancer Therapies)
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21 pages, 1407 KiB  
Review
Antibody-Based Approaches to Target Pancreatic Tumours
by Marie Sorbara, Pierre Cordelier and Nicolas Bery
Antibodies 2022, 11(3), 47; https://doi.org/10.3390/antib11030047 - 12 Jul 2022
Cited by 7 | Viewed by 4422
Abstract
Pancreatic cancer is an aggressive cancer with a dismal prognosis. This is due to the difficulty to detect the disease at an early and curable stage. In addition, only limited treatment options are available, and they are confronted by mechanisms of resistance. Monoclonal [...] Read more.
Pancreatic cancer is an aggressive cancer with a dismal prognosis. This is due to the difficulty to detect the disease at an early and curable stage. In addition, only limited treatment options are available, and they are confronted by mechanisms of resistance. Monoclonal antibody (mAb) molecules are highly specific biologics that can be directly used as a blocking agent or modified to deliver a drug payload depending on the desired outcome. They are widely used to target extracellular proteins, but they can also be employed to inhibit intracellular proteins, such as oncoproteins. While mAbs are a class of therapeutics that have been successfully employed to treat many cancers, they have shown only limited efficacy in pancreatic cancer as a monotherapy so far. In this review, we will discuss the challenges, opportunities and hopes to use mAbs for pancreatic cancer treatment, diagnostics and imagery. Full article
(This article belongs to the Special Issue Antibody Drug and Target Discovery for Cancer Therapies)
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16 pages, 4376 KiB  
Review
3D Models as a Tool to Assess the Anti-Tumor Efficacy of Therapeutic Antibodies: Advantages and Limitations
by Virginia Guzzeloni, Lorenzo Veschini, Federica Pedica, Elisabetta Ferrero and Marina Ferrarini
Antibodies 2022, 11(3), 46; https://doi.org/10.3390/antib11030046 - 08 Jul 2022
Cited by 3 | Viewed by 3452
Abstract
Therapeutic monoclonal antibodies (mAbs) are an emerging and very active frontier in clinical oncology, with hundred molecules currently in use or being tested. These treatments have already revolutionized clinical outcomes in both solid and hematological malignancies. However, identifying patients who are most likely [...] Read more.
Therapeutic monoclonal antibodies (mAbs) are an emerging and very active frontier in clinical oncology, with hundred molecules currently in use or being tested. These treatments have already revolutionized clinical outcomes in both solid and hematological malignancies. However, identifying patients who are most likely to benefit from mAbs treatment is currently challenging and limiting the impact of such therapies. To overcome this issue, and to fulfill the expectations of mAbs therapies, it is urgently required to develop proper culture models capable of faithfully reproducing the interactions between tumor and its surrounding native microenvironment (TME). Three-dimensional (3D) models which allow the assessment of the impact of drugs on tumors within its TME in a patient-specific context are promising avenues to progressively fill the gap between conventional 2D cultures and animal models, substantially contributing to the achievement of personalized medicine. This review aims to give a brief overview of the currently available 3D models, together with their specific exploitation for therapeutic mAbs testing, underlying advantages and current limitations to a broader use in preclinical oncology. Full article
(This article belongs to the Special Issue Women's Special Issue Series: Recent Development for Improved Therapeutic Antibodies)
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16 pages, 1638 KiB  
Review
FcγR-Mediated Trogocytosis 2.0: Revisiting History Gives Rise to a Unifying Hypothesis
by Margaret A. Lindorfer and Ronald P. Taylor
Antibodies 2022, 11(3), 45; https://doi.org/10.3390/antib11030045 - 05 Jul 2022
Cited by 9 | Viewed by 3146
Abstract
There is increasing interest in the clinical implications and immunology of trogocytosis, a process in which the receptors on acceptor cells remove and internalize cognate ligands from donor cells. We have reported that this phenomenon occurs in cancer immunotherapy, in which cells that [...] Read more.
There is increasing interest in the clinical implications and immunology of trogocytosis, a process in which the receptors on acceptor cells remove and internalize cognate ligands from donor cells. We have reported that this phenomenon occurs in cancer immunotherapy, in which cells that express FcγR remove and internalize CD20 and bound mAbs from malignant B cells. This process can be generalized to include other reactions including the immune adherence phenomenon and antibody-induced immunosuppression. We discuss in detail FcγR-mediated trogocytosis and the evidence supporting a proposed predominant role for liver sinusoidal endothelial cells via the action of the inhibitory receptor FcγRIIb2. We describe experiments to test the validity of this hypothesis. The elucidation of the details of FcγR-mediated trogocytosis has the potential to allow for the development of novel therapies that can potentially block or enhance this reaction, depending upon whether the process leads to unfavorable or positive biological effects. Full article
(This article belongs to the Special Issue Women's Special Issue Series: Recent Development for Improved Therapeutic Antibodies)
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11 pages, 561 KiB  
Review
Deciphering the Contribution of BP230 Autoantibodies in Bullous Pemphigoid
by Connor Cole, Luca Borradori and Kyle T. Amber
Antibodies 2022, 11(3), 44; https://doi.org/10.3390/antib11030044 - 28 Jun 2022
Cited by 5 | Viewed by 4416
Abstract
Bullous pemphigoid (BP) is a subepidermal autoimmune blistering disease predominantly affecting elderly patients and carries significant morbidity and mortality. Patients typically suffer from severe itch with eczematous lesions, urticarial plaques, and/or tense blisters. BP is characterized by the presence of circulating autoantibodies against [...] Read more.
Bullous pemphigoid (BP) is a subepidermal autoimmune blistering disease predominantly affecting elderly patients and carries significant morbidity and mortality. Patients typically suffer from severe itch with eczematous lesions, urticarial plaques, and/or tense blisters. BP is characterized by the presence of circulating autoantibodies against two components of the hemidesmosome, BP180 and BP230. The transmembrane BP180, also known as type XVII collagen or BPAG2, represents the primary pathogenic autoantigen in BP, whereas the intracellular BP230 autoantigen is thought to play a minor role in disease pathogenesis. Although experimental data exist suggesting that anti-BP230 antibodies are secondarily formed following initial tissue damage mediated by antibodies targeting extracellular antigenic regions of BP180, there is emerging evidence that anti-BP230 IgG autoantibodies alone directly contribute to tissue damage. It has been further claimed that a subset of patients has a milder variant of BP driven solely by anti-BP230 autoantibodies. Furthermore, the presence of anti-BP230 autoantibodies might correlate with distinct clinical features. This review summarizes the current understanding of the role of BP230 and anti-BP230 antibodies in BP pathogenesis. Full article
(This article belongs to the Special Issue Advances in the Use of Therapeutic Antibodies and Identification of Novel Autoantibodies in Dermatologic Disease)
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13 pages, 2815 KiB  
Article
Development of a Novel Anti-EpCAM Monoclonal Antibody for Various Applications
by Guanjie Li, Hiroyuki Suzuki, Teizo Asano, Tomohiro Tanaka, Hiroyoshi Suzuki, Mika K. Kaneko and Yukinari Kato
Antibodies 2022, 11(2), 41; https://doi.org/10.3390/antib11020041 - 08 Jun 2022
Cited by 14 | Viewed by 3738
Abstract
The epithelial cell adhesion molecule (EpCAM) is a cell surface glycoprotein, which is widely expressed on normal and cancer cells. EpCAM is involved in cell adhesion, proliferation, survival, stemness, and tumorigenesis. Therefore, EpCAM is thought to be a promising target for cancer diagnosis [...] Read more.
The epithelial cell adhesion molecule (EpCAM) is a cell surface glycoprotein, which is widely expressed on normal and cancer cells. EpCAM is involved in cell adhesion, proliferation, survival, stemness, and tumorigenesis. Therefore, EpCAM is thought to be a promising target for cancer diagnosis and therapy. In this study, we established anti-EpCAM monoclonal antibodies (mAbs) using the Cell-Based Immunization and Screening (CBIS) method. We characterized them using flow cytometry, Western blotting, and immunohistochemistry. One of the established recombinant anti-EpCAM mAbs, recEpMab-37 (mouse IgG1, kappa), reacted with EpCAM-overexpressed Chinese hamster ovary-K1 cells (CHO/EpCAM) or a colorectal carcinoma cell line (Caco-2). In contrast, recEpMab-37 did not react with EpCAM-knocked out Caco-2 cells. The KD of recEpMab-37 for CHO/EpCAM and Caco-2 was 2.0 × 10−8 M and 3.2 × 10−8 M, respectively. We observed that EpCAM amino acids between 144 to 164 are involved in recEpMab-37 binding. In Western blot analysis, recEpMab-37 detected the EpCAM of CHO/EpCAM and Caco-2 cells. Furthermore, recEpMab-37 could stain formalin-fixed paraffin-embedded colorectal carcinoma tissues by immunohistochemistry. Taken together, recEpMab-37, established by the CBIS method, is useful for detecting EpCAM in various applications. Full article
(This article belongs to the Special Issue Monoclonal Antibody-Directed Therapy Series II)
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10 pages, 1008 KiB  
Article
Kinetics of the Neutralizing and Spike SARS-CoV-2 Antibodies following the Sinovac Inactivated Virus Vaccine Compared to the Pfizer mRNA Vaccine in Singapore
by Chin Shern Lau, May Lin Helen Oh, Soon Kieng Phua, Ya Li Liang, Yanfeng Li, Jianxin Huo, Yuhan Huang, Biyan Zhang, Shengli Xu and Tar Choon Aw
Antibodies 2022, 11(2), 38; https://doi.org/10.3390/antib11020038 - 27 May 2022
Cited by 5 | Viewed by 2754
Abstract
Introduction: We compared the early total spike antibody (S-Ab) and neutralizing antibody (N-Ab) responses to two vaccines. Methods: We studied 96 Pfizer and 34 Sinovac vaccinees over a 14-month period from January 2021 to February 2022. All vaccinees received three doses of one [...] Read more.
Introduction: We compared the early total spike antibody (S-Ab) and neutralizing antibody (N-Ab) responses to two vaccines. Methods: We studied 96 Pfizer and 34 Sinovac vaccinees over a 14-month period from January 2021 to February 2022. All vaccinees received three doses of one type of vaccine. Antibody levels (Roche Elecsys total S-Ab and the Snibe N-Ab) were tested 10 days after the first dose, 20 days after the second dose, and 20 days after the booster dose. Results: At all time points, the mRNA vaccine generated higher S-Ab and N-Ab responses than the inactivated virus vaccine (S-Ab: first dose 2.48 vs. 0.4 BAU/mL, second dose 2174 vs. 98 BAU/mL, third dose 15,004 vs. 525 BAU/mL; N-Ab: first dose 0.05 vs. 0.02 µg/mL, second dose 3.48 vs. 0.38 µg/mL, third dose 19.8 vs. 0.89 µg/mL). mRNA vaccine recipients had a 6.2/22.2/28.6-fold higher S-Ab and 2.5/9.2/22.2-fold higher N-Ab response than inactivated virus vaccine recipients after the first/second/third inoculations, respectively. Mann–Whitney U analysis confirmed the significant difference in S-Ab and N-Ab titers between vaccination groups at each time point. Conclusions: The mRNA vaccines generated a more robust S-Ab and N-Ab response than the inactivated virus vaccine at all time points after the first, second, and third vaccinations. Full article
(This article belongs to the Special Issue Antibodies, B Cell Responses and Immune Responses to SARS-CoV-2 Infections)
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17 pages, 8390 KiB  
Review
A New Method to Characterize Conformation-Specific Antibody by a Combination of Agarose Native Gel Electrophoresis and Contact Blotting
by Teruo Akuta, Toshiaki Maruyama, Chiaki Sakuma, Masataka Nakagawa, Yui Tomioka, Kevin Entzminger, Jonathan K. Fleming, Ryo Sato, Takashi Shibata, Yasunori Kurosawa, C. J. Okumura and Tsutomu Arakawa
Antibodies 2022, 11(2), 36; https://doi.org/10.3390/antib11020036 - 12 May 2022
Cited by 6 | Viewed by 6677
Abstract
In this study, we review the agarose native gel electrophoresis that separates proteins and macromolecular complexes in their native state and transfer of the separated proteins from the agarose gel to membranes by contact blotting which retains the native state of these structures. [...] Read more.
In this study, we review the agarose native gel electrophoresis that separates proteins and macromolecular complexes in their native state and transfer of the separated proteins from the agarose gel to membranes by contact blotting which retains the native state of these structures. Green fluorescent protein showed functional state both on agarose gel and blotted membrane. Based on the combined procedures, we discovered conformation-specific monoclonal antibodies against PLXDC2 and SARS-CoV-2 spike protein. Full article
(This article belongs to the Special Issue Monoclonal Antibody-Directed Therapy Series II)
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19 pages, 3042 KiB  
Article
Mammalian Display Platform for the Maturation of Bispecific TCR-Based Molecules
by Janine Dilchert, Martin Hofmann, Felix Unverdorben, Roland Kontermann and Sebastian Bunk
Antibodies 2022, 11(2), 34; https://doi.org/10.3390/antib11020034 - 10 May 2022
Cited by 3 | Viewed by 4668
Abstract
Bispecific T cell receptor (TCR)-based molecules capable of redirecting and activating T cells towards tumor cells represent a novel and promising class of biotherapeutics for the treatment of cancer. Usage of TCRs allows for targeting of intracellularly expressed and highly selective cancer antigens, [...] Read more.
Bispecific T cell receptor (TCR)-based molecules capable of redirecting and activating T cells towards tumor cells represent a novel and promising class of biotherapeutics for the treatment of cancer. Usage of TCRs allows for targeting of intracellularly expressed and highly selective cancer antigens, but also requires a complex maturation process to increase the naturally low affinity and stability of TCRs. Even though TCR domains can be matured via phage and yeast display, these techniques share the disadvantages of non-human glycosylation patterns and the need for a later reformatting into the final bispecific format. Here, we describe the development and application of a Chinese Hamster Ovary (CHO) display for affinity engineering of TCRs in the context of the final bispecific TCR format. The recombinase-mediated cassette exchange (RCME)-based system allows for stable, single-copy integration of bispecific TCR molecules with high efficiency into a defined genetic locus of CHO cells. We used the system to isolate affinity-increased variants of bispecific T cell engaging receptor (TCER) molecules from a library encoding different CDR variants of a model TCR targeting preferentially expressed antigen in melanoma (PRAME). When expressed as a soluble protein, the selected TCER molecules exhibited strong reactivity against PRAME-positive tumor cells associated with a pronounced cytokine release from activated T cells. The obtained data support the usage of the CHO display-based maturation system for TCR affinity maturation in the context of the final bispecific TCER format. Full article
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10 pages, 536 KiB  
Review
Advances in Chimeric Antigen Receptor (CAR) T-Cell Therapies for the Treatment of Primary Brain Tumors
by Christopher W. Mount and Luis Nicolas Gonzalez Castro
Antibodies 2022, 11(2), 31; https://doi.org/10.3390/antib11020031 - 27 Apr 2022
Cited by 4 | Viewed by 3774
Abstract
Immunotherapy has revolutionized the care of cancer patients. A diverse set of strategies to overcome cancer immunosuppression and enhance the tumor-directed immune response are in clinical use, but have not achieved transformative benefits for brain tumor patients. Adoptive cell therapies, which employ a [...] Read more.
Immunotherapy has revolutionized the care of cancer patients. A diverse set of strategies to overcome cancer immunosuppression and enhance the tumor-directed immune response are in clinical use, but have not achieved transformative benefits for brain tumor patients. Adoptive cell therapies, which employ a patient’s own immune cells to generate directed anti-tumor activity, are emerging technologies that hold promise to improve the treatment of primary brain tumors in children and adults. Here, we review recent advances in chimeric antigen receptor (CAR) T-cell therapies for the treatment of aggressive primary brain tumors, including glioblastoma and diffuse midline glioma, H3 K27M-mutant. We highlight current approaches, discuss encouraging investigational data, and describe key challenges in the development and implementation of these types of therapies in the neuro-oncology setting. Full article
(This article belongs to the Special Issue CAR-T Cell Metabolism)
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13 pages, 1244 KiB  
Review
Precision-Cut Tumor Slices (PCTS) as an Ex Vivo Model in Immunotherapy Research
by Paraskevi Dimou, Sumita Trivedi, Maria Liousia, Reena R. D'Souza and Astero Klampatsa
Antibodies 2022, 11(2), 26; https://doi.org/10.3390/antib11020026 - 06 Apr 2022
Cited by 7 | Viewed by 6331
Abstract
Precision-cut tumor slices (PCTS) have recently emerged as important ex vivo human tumor models, offering the opportunity to study individual patient responses to targeted immunotherapies, including CAR-T cell therapies. In this review, an outline of different human tumor models available in laboratory settings [...] Read more.
Precision-cut tumor slices (PCTS) have recently emerged as important ex vivo human tumor models, offering the opportunity to study individual patient responses to targeted immunotherapies, including CAR-T cell therapies. In this review, an outline of different human tumor models available in laboratory settings is provided, with a focus on the unique characteristics of PCTS. Standard PCTS generation and maintenance procedures are outlined, followed by an in-depth overview of PCTS utilization in preclinical research aiming to better understand the unique functional characteristics of cytotoxic T cells within human tumors. Furthermore, recent studies using PCTS as an ex vivo model for predicting patient responses to immunotherapies and other targeted therapies against solid tumors are thoroughly presented. Finally, the advantages and limitations of the PCTS models are discussed. PCTS are expected to gain momentum and be fully utilized as a significant tool towards better patient stratification and personalized medicine. Full article
(This article belongs to the Special Issue CAR-T Cell Metabolism)
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17 pages, 1427 KiB  
Review
Cellular, Antibody and Cytokine Pathways in Children with Acute SARS-CoV-2 Infection and MIS-C—Can We Match the Puzzle?
by Snezhina Lazova, Yulia Dimitrova, Diana Hristova, Iren Tzotcheva and Tsvetelina Velikova
Antibodies 2022, 11(2), 25; https://doi.org/10.3390/antib11020025 - 01 Apr 2022
Cited by 10 | Viewed by 3681
Abstract
The newly identified strain of the Coronaviridae family called severe acute respiratory syndrome (SARS-CoV-2) recently became the most significant health threat for adults and children. Some main predictors of severe clinical course in patients with SARS-CoV-2 infection are age and concomitant health conditions. [...] Read more.
The newly identified strain of the Coronaviridae family called severe acute respiratory syndrome (SARS-CoV-2) recently became the most significant health threat for adults and children. Some main predictors of severe clinical course in patients with SARS-CoV-2 infection are age and concomitant health conditions. Therefore, the proper evaluation of SARS-CoV-2-specific immunity is urgently required to understand and predict the spectrum of possible clinical phenotypes and recommend vaccination options and regimens in children. Furthermore, it is critical to characterize the nature of SARS-CoV-2-specific immune responses in children following asymptomatic infection and COVID-19 and other related conditions such as multisystem inflammatory syndrome (MIS-C), para-infectious and late postinfectious consequences. Recent studies involving children revealed a variety of cytokines, T cells and antibody responses in the pathogenesis of the disease. Moreover, different clinical scenarios in children were observed-asymptomatic seroprevalence, acute SARS-CoV-2 infection, and rarely severe COVID-19 with typical cytokine storm, MIS-C, long COVID-19, etc. Therefore, to gain a better clinical view, adequate diagnostic criteria and treatment algorithms, it is essential to create a realistic picture of the immunological puzzle of SARS-CoV-2 infection in different age groups. Finally, it was demonstrated that children may exert a potent and prolonged adaptive anti-SARS-CoV-2 immune response, with significant cross-reactions against other human Corona Viruses, that might contribute to disease sparing effect in this age range. However, the immunopathology of the virus has to be elucidated first. Full article
(This article belongs to the Special Issue Antibodies, B Cell Responses and Immune Responses to SARS-CoV-2 Infections)
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19 pages, 3287 KiB  
Article
Effects of Monovalent Salt on Protein-Protein Interactions of Dilute and Concentrated Monoclonal Antibody Formulations
by Amy Y. Xu, Nicholas J. Clark, Joseph Pollastrini, Maribel Espinoza, Hyo-Jin Kim, Sekhar Kanapuram, Bruce Kerwin, Michael J. Treuheit, Susan Krueger, Arnold McAuley and Joseph E. Curtis
Antibodies 2022, 11(2), 24; https://doi.org/10.3390/antib11020024 - 31 Mar 2022
Cited by 7 | Viewed by 3833
Abstract
In this study, we used sodium chloride (NaCl) to extensively modulate non-specific protein-protein interactions (PPI) of a humanized anti-streptavidin monoclonal antibody class 2 molecule (ASA-IgG2). The changes in PPI with varying NaCl (CNaCl) and monoclonal antibody (mAb) concentration (C [...] Read more.
In this study, we used sodium chloride (NaCl) to extensively modulate non-specific protein-protein interactions (PPI) of a humanized anti-streptavidin monoclonal antibody class 2 molecule (ASA-IgG2). The changes in PPI with varying NaCl (CNaCl) and monoclonal antibody (mAb) concentration (CmAb) were assessed using the diffusion interaction parameter kD and second virial coefficient B22 measured from solutions with low to moderate CmAb. The effective structure factor S(q)eff measured from concentrated mAb solutions using small-angle X-ray and neutron scattering (SAXS/SANS) was also used to characterize the PPI. Our results found that the nature of net PPI changed not only with CNaCl, but also with increasing CmAb. As a result, parameters measured from dilute and concentrated mAb samples could lead to different predictions on the stability of mAb formulations. We also compared experimentally determined viscosity results with those predicted from interaction parameters, including kD and S(q)eff. The lack of a clear correlation between interaction parameters and measured viscosity values indicates that the relationship between viscosity and PPI is concentration-dependent. Collectively, the behavior of flexible mAb molecules in concentrated solutions may not be correctly predicted using models where proteins are considered to be uniform colloid particles defined by parameters derived from low CmAb. Full article
(This article belongs to the Special Issue Monoclonal Antibody-Directed Therapy Series II)
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14 pages, 2186 KiB  
Article
Highly Specific Monoclonal Antibody Targeting the Botulinum Neurotoxin Type E Exposed SNAP-25 Neoepitope
by Adva Mechaly, Eran Diamant, Ron Alcalay, Alon Ben David, Eyal Dor, Amram Torgeman, Ada Barnea, Meni Girshengorn, Lilach Levin, Eyal Epstein, Ariel Tennenhouse, Sarel J. Fleishman, Ran Zichel and Ohad Mazor
Antibodies 2022, 11(1), 21; https://doi.org/10.3390/antib11010021 - 16 Mar 2022
Cited by 5 | Viewed by 3498
Abstract
Botulinum neurotoxin type E (BoNT/E), the fastest acting toxin of all BoNTs, cleaves the 25 kDa synaptosomal-associated protein (SNAP-25) in motor neurons, leading to flaccid paralysis. The specific detection and quantification of the BoNT/E-cleaved SNAP-25 neoepitope can facilitate the development of cell-based assays [...] Read more.
Botulinum neurotoxin type E (BoNT/E), the fastest acting toxin of all BoNTs, cleaves the 25 kDa synaptosomal-associated protein (SNAP-25) in motor neurons, leading to flaccid paralysis. The specific detection and quantification of the BoNT/E-cleaved SNAP-25 neoepitope can facilitate the development of cell-based assays for the characterization of anti-BoNT/E antibody preparations. In order to isolate highly specific monoclonal antibodies suitable for the in vitro immuno-detection of the exposed neoepitope, mice and rabbits were immunized with an eight amino acid peptide composed of the C-terminus of the cleaved SNAP-25. The immunized rabbits developed a specific and robust polyclonal antibody response, whereas the immunized mice mostly demonstrated a weak antibody response that could not discriminate between the two forms of SNAP-25. An immune scFv phage-display library was constructed from the immunized rabbits and a panel of antibodies was isolated. The sequence alignment of the isolated clones revealed high similarity between both heavy and light chains with exceptionally short HCDR3 sequences. A chimeric scFv-Fc antibody was further expressed and characterized, exhibiting a selective, ultra-high affinity (pM) towards the SNAP-25 neoepitope. Moreover, this antibody enabled the sensitive detection of cleaved SNAP-25 in BoNT/E treated SiMa cells with no cross reactivity with the intact SNAP-25. Thus, by applying an immunization and selection procedure, we have isolated a novel, specific and high-affinity antibody against the BoNT/E-derived SNAP-25 neoepitope. This novel antibody can be applied in in vitro assays that determine the potency of antitoxin preparations and reduce the use of laboratory animals for these purposes. Full article
(This article belongs to the Special Issue Phage and Ribosome Display for Antibody Discovery and Optimization)
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15 pages, 1215 KiB  
Article
Reactivity of Rheumatoid Arthritis-Associated Citrulline-Dependent Antibodies to Epstein-Barr Virus Nuclear Antigen1-3
by Ilaria Fanelli, Paolo Rovero, Paul Robert Hansen, Jette Lautrup Frederiksen, Gunnar Houen and Nicole Hartwig Trier
Antibodies 2022, 11(1), 20; https://doi.org/10.3390/antib11010020 - 11 Mar 2022
Cited by 7 | Viewed by 2938
Abstract
Rheumatoid arthritis (RA) is a chronic disease which causes joint inflammation and, ultimately, erosion of the underlying bone. Diagnosis of RA is based on the presence of biomarkers, such as anti-citrullinated protein antibodies (ACPA) and rheumatoid factors, along with clinical symptoms. Much evidence [...] Read more.
Rheumatoid arthritis (RA) is a chronic disease which causes joint inflammation and, ultimately, erosion of the underlying bone. Diagnosis of RA is based on the presence of biomarkers, such as anti-citrullinated protein antibodies (ACPA) and rheumatoid factors, along with clinical symptoms. Much evidence points to a link between the Epstein-Barr virus and RA. In this study, we analyzed ACPA reactivity to citrullinated peptides originating from Epstein-Barr nuclear antigens (EBNA1, EBNA2, and EBNA3) in order to elaborate the diagnostic potential of citrullinated EBNA peptides. Moreover, ACPA cross-reactivity to citrullinated peptides from myelin basic protein (MBP) was analyzed, as citrullinated MBP recently was described to be associated with multiple sclerosis, and some degree of sequence homology between MBP and citrullinated EBNA exists. A peptide from EBNA2, (EBNA2-A, GQGRGRWRG-Cit-GSKGRGRMH) reacted with approximately 70% of all RA sera, whereas only limited reactivity was detected to EBNA1 and EBNA3 peptides. Moreover, screening of ACPA reactivity to hybrid peptides of EBNA3-A (EPDSRDQQS-Cit-GQRRGDENRG) and EBNA2-A and peptides containing citrulline close to the N-terminal confirmed that ACPA sera contain different populations of ACPAs. No notable ACPA reactivity to MBP peptides was found, confirming that ACPAs are specific for RA, and that other factors than the presence of a central Cit-Gly motif are crucial for antibody binding. Collectively, these findings illustrate that citrullinated EBNA2 is an optimal candidate for ACPA detection, supporting current evidence that EBV is linked to RA onset. Full article
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43 pages, 4424 KiB  
Article
Ramifications of the HLA-I Allelic Reactivity of Anti-HLA-E*01:01 and Anti-HLA-E*01:03 Heavy Chain Monoclonal Antibodies in Comparison with Anti-HLA-I IgG Reactivity in Non-Alloimmunized Males, Melanoma-Vaccine Recipients, and End-Stage Renal Disease Patients
by Mepur H. Ravindranath, Narendranath M. Ravindranath, Fatiha El Hilali, Senthamil R. Selvan and Edward J. Filippone
Antibodies 2022, 11(1), 18; https://doi.org/10.3390/antib11010018 - 02 Mar 2022
Cited by 4 | Viewed by 3007
Abstract
Serum anti-HLA-I IgG are present in non-alloimmunized males, cancer patients, and transplant recipients. Anti-HLA-I antibodies are also present in intravenous immunoglobulin (IVIg), prepared from the plasma of thousands of healthy donors. However, the HLA-Ia reactivity of IVIg diminishes markedly after passing through HLA-E [...] Read more.
Serum anti-HLA-I IgG are present in non-alloimmunized males, cancer patients, and transplant recipients. Anti-HLA-I antibodies are also present in intravenous immunoglobulin (IVIg), prepared from the plasma of thousands of healthy donors. However, the HLA-Ia reactivity of IVIg diminishes markedly after passing through HLA-E HC-affinity columns, suggesting that the HLA-I reactivity is due to antibodies formed against HLA-E. Hence, we examined whether anti-HLA-E antibodies can react to HLA-I alleles. Monoclonal IgG antibodies (mAbs) against HCs of two HLA-E alleles were generated in Balb/C mice. The antibodies were analyzed using multiplex bead assays on a Luminex platform for HLA-I reactivity. Beads coated with an array of HLA heterodimers admixed with HCs (LABScreen) were used to examine the binding of IgG to different HLA-Ia (31-HLA-A, 50-HLA-B, and 16-HLA-C) and Ib (2-HLA-E, one each of HLA-F and HLA-G) alleles. A striking diversity in the HLA-Ia and/or HLA-Ib reactivity of mAbs was observed. The number of the mAbs reactive to (1) only HLA-E (n = 25); (2) all HLA-Ib isomers (n = 8); (3) HLA-E and HLA-B (n = 5); (4) HLA-E, HLA-B, and HLA-C (n = 30); (5) HLA-E, HLA-A*1101, HLA-B, and HLA-C (n = 83); (6) HLA-E, HLA-A, HLA-B, and HLA-C (n = 54); and (7) HLA-Ib and HLA-Ia (n = 8), in addition to four other minor groups. Monospecificity and polyreactivity were corroborated by HLA-E monospecific and HLA-I shared sequences. The diverse HLA-I reactivity of the mAbs are compared with the pattern of HLA-I reactivity of serum-IgG in non-alloimmunized males, cancer patients, and ESKD patients. The findings unravel the diagnostic potential of the HLA-E monospecific-mAbs and immunomodulatory potentials of IVIg highly mimicking HLA-I polyreactive-mAbs. Full article
(This article belongs to the Special Issue Monoclonal Antibody-Directed Therapy Series II)
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41 pages, 1578 KiB  
Review
Immune- and Non-Immune-Mediated Adverse Effects of Monoclonal Antibody Therapy: A Survey of 110 Approved Antibodies
by Brian A. Baldo
Antibodies 2022, 11(1), 17; https://doi.org/10.3390/antib11010017 - 25 Feb 2022
Cited by 16 | Viewed by 9236
Abstract
Identification of new disease-associated biomarkers; specific targeting of such markers by monoclonal antibodies (mAbs); and application of advances in recombinant technology, including the production of humanized and fully human antibodies, has enabled many improved treatment outcomes and successful new biological treatments of some [...] Read more.
Identification of new disease-associated biomarkers; specific targeting of such markers by monoclonal antibodies (mAbs); and application of advances in recombinant technology, including the production of humanized and fully human antibodies, has enabled many improved treatment outcomes and successful new biological treatments of some diseases previously neglected or with poor prognoses. Of the 110 mAbs preparations currently approved by the FDA and/or EMA, 46 (including 13 antibody–drug conjugates) recognizing 29 different targets are indicated for the treatment of cancers, and 66, recognizing 48 different targets, are indicated for non-cancer disorders. Despite their specific targeting with the expected accompanying reduced collateral damage for normal healthy non-involved cells, mAbs, may cause types I (anaphylaxis, urticaria), II (e.g., hemolytic anemia, possibly early-onset neutropenia), III (serum sickness, pneumonitis), and IV (Stevens–Johnson syndrome, toxic epidermal necrolysis) hypersensitivities as well as other cutaneous, pulmonary, cardiac, and liver adverse events. MAbs can provoke severe infusion reactions that resemble anaphylaxis and induce a number of systemic, potentially life-threatening syndromes with low frequency. A common feature of most of these syndromes is the release of a cascade of cytokines associated with inflammatory and immunological processes. Epidermal growth factor receptor-targeted antibodies may provoke papulopustular and mucocutaneous eruptions that are not immune-mediated. Full article
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14 pages, 2088 KiB  
Review
The Role of Bispecific Antibodies in Non-Hodgkin’s Lymphoma: From Structure to Prospective Clinical Use
by Rita Tavarozzi and Enrica Manzato
Antibodies 2022, 11(1), 16; https://doi.org/10.3390/antib11010016 - 21 Feb 2022
Cited by 8 | Viewed by 6787
Abstract
Bispecific antibodies (bsAbs) are molecules that simultaneously bind two different antigens (Ags). bsAbs represent a very active field in tumor immunotherapy with more than one hundred molecules currently being tested. More specifically, they have elicited a great interest in the setting of non-Hodgkin’s [...] Read more.
Bispecific antibodies (bsAbs) are molecules that simultaneously bind two different antigens (Ags). bsAbs represent a very active field in tumor immunotherapy with more than one hundred molecules currently being tested. More specifically, they have elicited a great interest in the setting of non-Hodgkin’s lymphoma (NHLs), where they could represent a viable option for more fragile patients or those resistant to other conventional therapies. This review aims to give a brief overview of the different available bsAb formats and their mechanisms of action, pinpointing the differences between IgG-like and non-IgG-like classes and will then focus on those in advanced clinical development for NHLs. Full article
(This article belongs to the Special Issue Reviews on Antibodies and Antigens)
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13 pages, 1493 KiB  
Article
Anti-SARS-CoV-2 Omicron Antibodies Isolated from a SARS-CoV-2 Delta Semi-Immune Phage Display Library
by Ivette Mendoza-Salazar, Keyla M. Gómez-Castellano, Edith González-González, Ramsés Gamboa-Suasnavart, Stefany D. Rodríguez-Luna, Giovanni Santiago-Casas, María I. Cortés-Paniagua, Sonia M. Pérez-Tapia and Juan C. Almagro
Antibodies 2022, 11(1), 13; https://doi.org/10.3390/antib11010013 - 10 Feb 2022
Cited by 7 | Viewed by 4485
Abstract
This report describes the discovery and characterization of antibodies with potential broad SARS-CoV-2 neutralization profiles. The antibodies were obtained from a phage display library built with the VH repertoire of a convalescent COVID-19 patient who was infected with SARS-CoV-2 B.1.617.2 (Delta). The patient [...] Read more.
This report describes the discovery and characterization of antibodies with potential broad SARS-CoV-2 neutralization profiles. The antibodies were obtained from a phage display library built with the VH repertoire of a convalescent COVID-19 patient who was infected with SARS-CoV-2 B.1.617.2 (Delta). The patient received a single dose of Ad5-nCoV vaccine (Convidecia™, CanSino Biologics Inc.) one month before developing COVID-19 symptoms. Four synthetic VL libraries were used as counterparts of the immune VH repertoire. After three rounds of panning with SARS-CoV-2 receptor-binding domain wildtype (RBD-WT) 34 unique scFvs, were identified, with 27 cross-reactive for the RBD-WT and RBD Delta (RBD-DT), and seven specifics for the RBD-WT. The cross-reactive scFvs were more diverse than the RBD-WT specific ones, being encoded by several IGHV genes from the IGHV1 and IGHV3 families combined with short HCDR3s. Six cross-reactive scFvs and one RBD-WT specific scFv were converted to human IgG1 (hIgG1). Out of the seven antibodies, six blocked the RBD-WT binding to angiotensin converting enzyme 2 (ACE2), suggesting these antibodies may neutralize the SARS-CoV-2 infection. Importantly, one of the antibodies also recognized the RBD from the B.1.1.529 (Omicron) isolate, implying that the VH repertoire of the convalescent patient would protect against SARS-CoV-2 Wildtype, Delta, and Omicron. From a practical viewpoint, the triple cross-reactive antibody provides the substrate for developing therapeutic antibodies with a broad SARS-CoV-2 neutralization profile. Full article
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22 pages, 3270 KiB  
Article
Cryopreservation of Natural Killer Cells Pre-Complexed with Innate Cell Engagers
by Uwe Reusch, Kristina Ellwanger, Ivica Fucek, Thomas Müller, Ute Schniegler-Mattox, Joachim Koch and Michael Tesar
Antibodies 2022, 11(1), 12; https://doi.org/10.3390/antib11010012 - 09 Feb 2022
Cited by 5 | Viewed by 7525
Abstract
Innate cell engager (ICE®) constructs are bispecific tetravalent antibodies targeting specific tumor antigens and simultaneously engaging natural killer (NK) cell and macrophage receptors for the destruction of tumor cells. Pre-complexing of ICE® constructs with adoptive NK cells is a novel [...] Read more.
Innate cell engager (ICE®) constructs are bispecific tetravalent antibodies targeting specific tumor antigens and simultaneously engaging natural killer (NK) cell and macrophage receptors for the destruction of tumor cells. Pre-complexing of ICE® constructs with adoptive NK cells is a novel approach to enhance NK cell activity. The suitability of such complexes for cryopreservation, whilst retaining the biological activity and specificity, may enable the development of off-the-shelf NK cell products. This study investigates the binding affinity of ICE® constructs targeting EpCAM and NK cell receptors CD16A, NKG2D, or NKp46 to the corresponding antigens, the ICE® antitumor activity, and feasibility of cryopreservation. Cell surface retention assays using primary NK cells confirmed a substantially slower ICE® construct dissociation kinetics compared with control molecules, suggesting the formation of durable complexes independently of the CD16A polymorphism. The high-affinity NK cell and EpCAM/CD16A ICE® complexes were superior to those engaging NKG2D or NKp46 receptors when tested for the NK-cell-mediated elimination of EpCAM-expressing tumor cells. Moreover, the potency and efficacy of these complexes were unaffected after a single freeze–thaw cycle. CD16A-selective ICE® drug candidates complexed with NK cells hold promise as novel cryopreserved off-the-shelf NK cell products with chimeric antigen receptor-like NK cell properties, capable of effective depletion of tumor cells. Full article
(This article belongs to the Special Issue Antibodies for Effector Cell Redirection)
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18 pages, 2608 KiB  
Article
Functional Changes of Therapeutic Antibodies upon Exposure to Pro-Oxidative Agents
by Maxime Lecerf, Robin Lacombe, Alexia Kanyavuz and Jordan D. Dimitrov
Antibodies 2022, 11(1), 11; https://doi.org/10.3390/antib11010011 - 02 Feb 2022
Cited by 5 | Viewed by 2966
Abstract
Therapeutic monoclonal antibodies have exerted a transformative impact on clinical practice in last two decades. However, development of a therapeutic antibody remains a complex process. Various physiochemical and functional liabilities can compromise the production or the therapeutic efficacy of antibodies. One of these [...] Read more.
Therapeutic monoclonal antibodies have exerted a transformative impact on clinical practice in last two decades. However, development of a therapeutic antibody remains a complex process. Various physiochemical and functional liabilities can compromise the production or the therapeutic efficacy of antibodies. One of these liabilities is the susceptibility to oxidation. In the present study, we portrayed an oxidation-dependent vulnerability of immunoglobulins that can be of concern for therapeutic antibodies. By using a library of 119 monoclonal IgG1 molecules, containing variable domain matching clinical-stage antibodies, we demonstrated that a substantial number of these molecules acquired antigen-binding polyreactivity upon exposure to ferrous ions. Statistical analyses revealed that the potential for induction of polyreactivity by the redox-active metal ions correlated with a higher number of somatic mutations in V genes encoding variable domains of heavy and light immunoglobulin chains. Moreover, the sensitive antibodies used with biased frequencies particular V gene families encoding variable domains of their light chains. Besides the exposure to ferrous ions the induction of polyreactivity of therapeutic antibodies occurred after contact with an unrelated pro-oxidative substance—hypochlorite ions. Our data also revealed that induction of polyreactivity by pro-oxidative agents did not impact the binding of antibodies to their cognate antigens. The results from this study may contribute for better selection of antibody therapeutics with suitable developability profiles. Full article
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18 pages, 2882 KiB  
Article
Construction of a Humanized Artificial VHH Library Reproducing Structural Features of Camelid VHHs for Therapeutics
by Taihei Murakami, Shigefumi Kumachi, Yasuhiro Matsunaga, Miwa Sato, Kanako Wakabayashi-Nakao, Hidekazu Masaki, Ryo Yonehara, Maiko Motohashi, Naoto Nemoto and Masayuki Tsuchiya
Antibodies 2022, 11(1), 10; https://doi.org/10.3390/antib11010010 - 30 Jan 2022
Cited by 8 | Viewed by 8243
Abstract
A variable domain of heavy chain antibody (VHH) has different binding properties than conventional antibodies. Conventional antibodies prefer binding to the convex portion of the antigen, whereas VHHs prefer epitopes, such as crevices and clefts on the antigen. Therefore, developing candidates with the [...] Read more.
A variable domain of heavy chain antibody (VHH) has different binding properties than conventional antibodies. Conventional antibodies prefer binding to the convex portion of the antigen, whereas VHHs prefer epitopes, such as crevices and clefts on the antigen. Therefore, developing candidates with the binding characteristics of camelid VHHs is important. Thus, To this end, a synthetic VHH library that reproduces the structural properties of camelid VHHs was constructed. First, the characteristics of VHHs were classified according to the paratope formation based on crystal structure analyses of the complex structures of VHHs and antigens. Then, we classified 330 complementarity-determining region 3 (CDR3) structures of VHHs from the Protein Data Bank (PDB) into three loop structures: Upright, Half-Roll, and Roll. Moreover, these structures depended on the number of amino acid residues within CDR3. Furthermore, in the Upright loops, several amino acid residues in the FR2 are involved in the paratope formation, along with CDR3, suggesting that the FR2 design in the synthetic library is important. A humanized synthetic VHH library, comprising two sub-libraries, Upright and Roll, was constructed and named PharmaLogical. A validation study confirmed that our PharmaLogical library reproduces VHHs with the characteristics of the paratope formation of the camelid VHHs, and shows good performance in VHH screening. Full article
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14 pages, 912 KiB  
Review
Applications of Antibody-Based Antigen Delivery Targeted to Dendritic Cells In Vivo
by Jessica Bourque and Daniel Hawiger
Antibodies 2022, 11(1), 8; https://doi.org/10.3390/antib11010008 - 25 Jan 2022
Cited by 7 | Viewed by 6469
Abstract
Recombinant immunoglobulins, derived from monoclonal antibodies recognizing the defined surface epitopes expressed on dendritic cells, have been employed for the past two decades to deliver antigens to dendritic cells in vivo, serving as critical tools for the investigation of the corresponding T cell [...] Read more.
Recombinant immunoglobulins, derived from monoclonal antibodies recognizing the defined surface epitopes expressed on dendritic cells, have been employed for the past two decades to deliver antigens to dendritic cells in vivo, serving as critical tools for the investigation of the corresponding T cell responses. These approaches originated with the development of the recombinant chimeric antibody against a multilectin receptor, DEC-205, which is present on subsets of murine and human conventional dendritic cells. Following the widespread application of antigen targeting through DEC-205, similar approaches then utilized other epitopes as entry points for antigens delivered by specific antibodies to multiple types of dendritic cells. Overall, these antigen-delivery methodologies helped to reveal the mechanisms underlying tolerogenic and immunogenic T cell responses orchestrated by dendritic cells. Here, we discuss the relevant experimental strategies as well as their future perspectives, including their translational relevance. Full article
(This article belongs to the Special Issue Reviews on Antibodies and Antigens)
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13 pages, 1390 KiB  
Review
Antibodies against Platelet Factor 4 and Their Associated Pathologies: From HIT/HITT to Spontaneous HIT-Like Syndrome, to COVID-19, to VITT/TTS
by Emmanuel J. Favaloro, Leonardo Pasalic and Giuseppe Lippi
Antibodies 2022, 11(1), 7; https://doi.org/10.3390/antib11010007 - 21 Jan 2022
Cited by 15 | Viewed by 4073
Abstract
Antibodies against platelet factor 4 (PF4), a protein released from alpha-granules of activated platelets, may cause a number of pathophysiological conditions. The most commonly known is heparin-induced thrombocytopenia (HIT), which develops in a small proportion of people treated with the anticoagulant drug heparin. [...] Read more.
Antibodies against platelet factor 4 (PF4), a protein released from alpha-granules of activated platelets, may cause a number of pathophysiological conditions. The most commonly known is heparin-induced thrombocytopenia (HIT), which develops in a small proportion of people treated with the anticoagulant drug heparin. Notably, PF4 binds with high affinity to heparin, and in HIT, complexes of PF4/H may, in a small proportion of susceptible patients, trigger the development of anti-PF4 antibodies and subsequent platelet activation and aggregation, ultimately leading to the development of pathological thrombosis at sites of vessel occlusion. Of more modern interest, antibodies against PF4 may also arise in patients with COVID-19 (Coronavirus Disease 2019) or in patients who have been vaccinated against COVID-19, especially in recipients of adenovirus-based vaccines. For this latter group of patients, the terms VITT (vaccine-induced [immune] thrombotic thrombocytopenia) and TTS (thrombotic thrombocytopenia syndrome) have been coined. Another category associated with this pathophysiology comprises those in whom a precipitating event is not clear; this category is referred to as ‘spontaneous HIT-like syndrome’. Despite its name, it arises as an HIT-mimicking disorder but without antecedent heparin exposure. In this narrative review, we describe the development of antibodies against PF4, and associated pathophysiology, in such conditions. Full article
(This article belongs to the Special Issue Reviews on Antibodies and Antigens)
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14 pages, 2288 KiB  
Article
Engineering an Enhanced EGFR Engager: Humanization of Cetuximab for Improved Developability
by Dennis R. Goulet, Soumili Chatterjee, Wai-Ping Lee, Andrew B. Waight, Yi Zhu and Amanda Nga-Sze Mak
Antibodies 2022, 11(1), 6; https://doi.org/10.3390/antib11010006 - 13 Jan 2022
Cited by 8 | Viewed by 4574
Abstract
The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase whose proliferative effects can contribute to the development of many types of solid tumors when overexpressed. For this reason, EGFR inhibitors such as cetuximab can play an important role in treating cancers [...] Read more.
The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase whose proliferative effects can contribute to the development of many types of solid tumors when overexpressed. For this reason, EGFR inhibitors such as cetuximab can play an important role in treating cancers such as colorectal cancer and head and neck cancer. Cetuximab is a chimeric monoclonal antibody containing mouse variable regions that bind to EGFR and prevent it from signaling. Although cetuximab has been used clinically since 2004 to successfully control solid tumors, advances in protein engineering have created the opportunity to address some of its shortcomings. In particular, the presence of mouse sequences could contribute to immunogenicity in the form of anti-cetuximab antibodies, and an occupied glycosylation site in FR3 can contribute to hypersensitivity reactions and product heterogeneity. Using simple framework graft or sequence-/structure-guided approaches, cetuximab was humanized onto 11 new frameworks. In addition to increasing humanness and removing the VH glycosylation site, dynamic light scattering revealed increases in stability, and bio-layer interferometry confirmed minimal changes in binding affinity, with patterns emerging across the humanization method. This work demonstrates the potential to improve the biophysical and clinical properties of first-generation protein therapeutics and highlights the advantages of computationally guided engineering. Full article
(This article belongs to the Special Issue Monoclonal Antibody-Directed Therapy Series II)
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