Targeting FcRn for immunomodulation: Benefits, risks, and practical considerations

Novel therapies in CIDP

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a heterogeneous but clinically well-described disease within circumscribed parameters. It is immunologically mediated through several poorly understood mechanisms. First-line therapies with steroids, intravenous immunoglobulin (IVIG) or plasma exchange are each effective in about two-thirds of patients. These treatments are seldom associated with complete resolution or cure, and often pose considerable practical, financial and medical implications.Our understanding of many of the key pathological processes in autoimmune diseases is expanding, and novel targeted therapeutics are being developed with promise in several autoimmune neurological disorders.This narrative review looks first at detailing key pathogenic mechanisms of disease in CIDP, followed by an in-depth description of potential novel therapies and the current evidence of their application in clinical practice.

Current state and potential applications of neonatal Fc receptor (FcRn) inhibitors in hematologic conditions

The neonatal fragment crystallizable (Fc) receptor (FcRn) transports IgG across mucosal surfaces and the placenta and protects IgG from degradation. Numerous clinical trials are investigating therapeutic FcRn inhibition for various immune-mediated neuromuscular and rheumatologic conditions; however, FcRn inhibition also represents a potential therapy for IgG-mediated hematologic conditions (e.g., immune thrombocytopenia, autoimmune hemolytic anemia, immune thrombotic thrombocytopenic purpura, acquired hemophilia, red blood cell/platelet alloimmunization). Current evidence derived from both in vitro and in vivo studies suggests that FcRn inhibitors effectively reduce total IgG levels without impacting its production or altering the levels of other immunoglobulin isotypes. Moreover, the risk of serious adverse events, including serious infections, appears to be lower than that seen with other commonly used immunomodulatory/immunosuppressive therapies, albeit in the setting of limited clinical trial data. Ultimately, additional clinical trials that include varied patient populations are required prior to incorporating these agents into standard treatment algorithms for most hematologic conditions. However, based on the pathophysiology of IgG-mediated hematologic disorders and the mechanism of action of FcRn inhibitors, these agents may represent a future novel therapeutic strategy for patients with hematologic conditions caused by IgG antibodies.

Maternal influences on offspring food allergy

The prevalence of allergies has been globally escalating. While allergies could appear at any age, they often develop in early life. However, the significant knowledge gap in the field is the mechanisms by which allergies affect certain people but not others. Investigating early factors and events in neonatal life that have a lasting impact on determining the susceptibilities of children to develop allergies is a significant area of the investigation as it promotes the understanding of neonatal immune system that mediates tolerance versus allergies. This review focuses on the research over the recent 10 years regarding the potential maternal factors that influence offspring allergies with a view to food allergy, a potentially life-threatening cause of anaphylaxis. The role of breast milk, maternal diet, maternal antibodies, and microbiota that have been suggested as key maternal factors regulating offspring allergies are discussed here. We also suggest future research area to expand our knowledge of maternal-offspring interactions on the pathogenesis of food allergy.

Efgartigimod as a novel FcRn inhibitor for autoimmune disease

Immunoglobulin G (IgG) autoantibodies can lead to the formation of autoimmune diseases through Fab and/or Fc-mediated interactions with host molecules as well as activated T cells. The neonatal Fc receptor (FcRn) binds at acidic pH IgG and albumin, and the mechanism for prolonging serum IgG half-life is making IgG re-entry into circulation by prompting it not to be degraded by lysosomes and back to the cell surface. Given the FcRn receptor's essential role in IgG homeostasis, one of the strategies to promote the quick degradation of endogenous IgG is to suppress the function of FcRn, which is beneficial to the treatment of IgG-driven autoimmune disorders like myasthenia gravis (MG), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), stiff person syndrome, and immune thrombocytopenia (ITP). We elaborately read the literature about efgartigimod and systematically reviewed the research progress and clinical application of this novel FcRn inhibitor in autoimmune diseases. Efgartigimod is the firstly FcRn antagonist developed and was approved on 17 December 2021 by the United States for the therapy of acetylcholine receptor-positive MG. In January 2022, efgartigimod received its second regulatory approval in Japan. In addition, the market authorization application in Europe was submitted and validated in August 2021. China's National Medical Products Administration officially accepted the marketing application of efgartigimod on July 13, 2022. To suppress the function of FcRn, which is beneficial to the treatment of IgG-driven autoimmune disorders like MG, CIDP, ITP, and stiff person syndrome. We review the rationale, clinical evidence, and future perspectives of efgartigimod for the treatment of autoimmune disease.

Targeted Treatments for Myasthenia Gravis in Children and Adolescents

Myasthenia gravis (MG) is an antibody-mediated disorder of the neuromuscular junction affecting children and adults. MG is a treatable condition with most patients requiring immunosuppression for disease control and/or remission. Juvenile myasthenia gravis (JMG) is rare in comparison with adult-onset MG but given the same underlying pathophysiology, treatment strategies are similar to those in adults. Until recently, there were only a few randomised controlled trials (RCTs) for MG treatments in adults and none in children, and management strategies were primarily based on expert consensus. In addition, treatment options for refractory MG cases have been severely limited, resulting in poor long-term quality of life in such patients due to the significant disease burden. Recently, there have been several RCTs focussing on novel therapeutic strategies with potentially promising outcomes, suggesting a change in MG management over the coming years and access to more effective and faster-acting drugs for MG patients. This paper will review current and new MG treatments including efgartigimod, eculizumab, rozanolixizumab, ravulizumab, and zilucoplan, with a focus on juvenile myasthenia gravis.

Pharmacokinetics and Pharmacodynamics of Nipocalimab, a Neonatal Fc Receptor Blocker, in Healthy Japanese Volunteers

BACKGROUND AND OBJECTIVES

Nipocalimab is a high-affinity, fully human, effectorless immunoglobulin G1 monoclonal antibody targeting the neonatal Fc receptor and is currently under evaluation for the treatment of rare and prevalent immunoglobulin G autoantibody-mediated and alloantibody-mediated diseases. This phase I, randomized, double-blind, placebo-controlled, single-dose escalation study in healthy Japanese volunteers (N = 24) assessed the safety, pharmacokinetics, and effect on the serum immunoglobulin G level of single doses of nipocalimab.

METHODS

Volunteers were grouped into three cohorts and received intravenous nipocalimab at 10, 30, or 60 mg/kg or placebo. To complement the study, genetic variation in the Fcγ receptor and transporter subunit of the neonatal Fc receptor was analyzed in Japanese and diverse populations.

RESULTS

Nipocalimab was generally safe and well tolerated at all dose levels, with three (12.5% [3/24]) volunteers experiencing treatment-emergent adverse events across all nipocalimab doses. Mean serum immunoglobulin G levels decreased in a dose-dependent manner from baseline with nipocalimab treatment compared with placebo. Maximum serum nipocalimab concentrations demonstrated proportional increases with dose, while the area under the concentration-time curve was dose dependent and demonstrated non-linear increases with dose. Mean observed half-life was longer as the dose increased. Analysis of genetic variation in Fcγ receptor and transporter identified no unique Japanese variants or variants that alter amino acid sequences in or near the neonatal Fc receptor immunoglobulin G binding site targeted by nipocalimab.

CONCLUSIONS

The comparable pharmacokinetic/pharmacodynamic profiles and highly conserved neonatal Fc receptor structure among diverse populations further support the clinical development of nipocalimab for the treatment of various immunoglobulin G autoantibody-mediated and alloantibody-mediated diseases across global sites and populations, including the Japanese population.

Rhesus Macaques: VNTR Polymorphism of the FCGRT Gene

Variable number tandem repeat (VNTR) polymorphisms of the human neonatal IgG Fc receptor α-chain gene (FCGRT) are known to influence the expression levels of FCGRT and IgG in serum. Monkeys are considered to be a relevant biological model for studying the effects of immunobiological drugs. The study determined the functional VNTR polymorphisms of the FCGRT gene in 109 male rhesus macaques from the nursery of the Kurchatov Complex of Medical Primatology. PCR amplification of samples was carried out followed by electrophoretic separation of DNA fragments in a 2% agarose gel. Individual DNA amplification products were sequenced (according to Sanger system) in forward and reverse directions to confirm the specificity. The genotyping showed that the VNTR polymorphism of the FCGRT gene in the studied population of rhesus macaques is presented by 9 variants. The frequency of the VNTR5 allele associated with lower IgG levels was 14.2%, and the most common one was the VNTR7 allele (25.2%). We also identified alleles that have not been previously reported: VNTR3, VNTR4, VNTR6, VNTR8, and VNTR9. The study allows to consider rhesus macaques as a potential model for studying the immunological response depending on the genetic VNTR variant of FCGRT.

Charting a course for global progress in PIDs by 2030 - proceedings from the IPOPI global multi-stakeholders' summit (September 2023)

The International Patient Organisation for Primary Immunodeficiencies (IPOPI) held its second Global Multi-Stakeholders' Summit, an annual stimulating and forward-thinking meeting uniting experts to anticipate pivotal upcoming challenges and opportunities in the field of primary immunodeficiency (PID). The 2023 summit focused on three key identified discussion points: (i) How can immunoglobulin (Ig) therapy meet future personalized patient needs? (ii) Pandemic preparedness: what's next for public health and potential challenges for the PID community? (iii) Diagnosing PIDs in 2030: what needs to happen to diagnose better and to diagnose more? Clinician-Scientists, patient representatives and other stakeholders explored avenues to improve Ig therapy through mechanistic insights and tailored Ig preparations/products according to patient-specific needs and local exposure to infectious agents, amongst others. Urgency for pandemic preparedness was discussed, as was the threat of shortage of antibiotics and increasing antimicrobial resistance, emphasizing the need for representation of PID patients and other vulnerable populations throughout crisis and care management. Discussion also covered the complexities of PID diagnosis, addressing issues such as global diagnostic disparities, the integration of patient-reported outcome measures, and the potential of artificial intelligence to increase PID diagnosis rates and to enhance diagnostic precision. These proceedings outline the outcomes and recommendations arising from the 2023 IPOPI Global Multi-Stakeholders' Summit, offering valuable insights to inform future strategies in PID management and care. Integral to this initiative is its role in fostering collaborative efforts among stakeholders to prepare for the multiple challenges facing the global PID community.

Cancer therapy with antibodies

The greatest challenge in cancer therapy is to eradicate cancer cells with minimal damage to normal cells. Targeted therapy has been developed to meet that challenge, showing a substantially increased therapeutic index compared with conventional cancer therapies. Antibodies are important members of the family of targeted therapeutic agents because of their extraordinarily high specificity to the target antigens. Therapeutic antibodies use a range of mechanisms that directly or indirectly kill the cancer cells. Early antibodies were developed to directly antagonize targets on cancer cells. This was followed by advancements in linker technologies that allowed the production of antibody-drug conjugates (ADCs) that guide cytotoxic payloads to the cancer cells. Improvement in our understanding of the biology of T cells led to the production of immune checkpoint-inhibiting antibodies that indirectly kill the cancer cells through activation of the T cells. Even more recently, bispecific antibodies were synthetically designed to redirect the T cells of a patient to kill the cancer cells. In this Review, we summarize the different approaches used by therapeutic antibodies to target cancer cells. We discuss their mechanisms of action, the structural basis for target specificity, clinical applications and the ongoing research to improve efficacy and reduce toxicity.

A Review of Novel Medical Treatments for Thyroid Eye Disease

Thyroid eye disease (TED) is the most common extrathyroidal manifestation of Graves disease. There has been no effective medication to prevent proptosis in thyroid eye disease until 2020 when the anti-insulin-like growth factor 1 receptor (anti-IGF-1R) antibody, Teprotumumab, was approved by the US Food and Drug Administration, sparking increased interest in immune-based drug development. This study aims to review the newly developed drug therapy as well as conventional treatment for TED. Treatment of TED has traditionally been high-dose steroids and orbital radiotherapy, but recently there has been a paradigm shift in the treatment of TED in the United States with the introduction of the therapeutic agent teprotumumab, which dramatically reduces proptosis. However, concerns remain about the development of hearing impairment as a potentially fatal complication and long-term safety. Recently, several clinical trials are underway to assess the efficacy and safety of novel drugs targeting mammalian target of rapamycin complex 1, interleukin-6, fragment crystallizable receptor, and IGF-1R in treating TED. With the explosive increase in interest from academia and pharmaceutical companies in TED, there is anticipation for the development of drugs that are equivalent or superior to teprotumumab while being safer.

The changing landscape of thyroid eye disease: current clinical advances and future outlook

AIMS

This review aims to provide an overview of the current understanding of TED and its pathophysiology. To describe the evidence base for current consensus treatment recommendations and newer biological therapies available as well as to present future therapeutic research.

METHODS

We reviewed and assessed the peer-reviewed literature placing particular emphasis on recent studies evaluating the pathophysiology of TED, landmark trials forming the basis of current management and recent clinical trials informing future therapeutics. Searched were made in MEDLINE Ovid, Embase Ovid, US National Institutes of Health Ongoing Trials Register and EU Clinical Trials Register. Keywords included: "Thyroid Eye Disease", "Graves Orbitopathy", "Thyroid Orbitopathy" and "Graves' Ophthalmopathy".

RESULTS AND CONCLUSIONS

The pathophysiology of TED involves a complex array of cellular and humoral based autoimmune dysfunction. Previous therapies have been broad-based acting as a blunt instrument on this mechanism with varying efficacy but often accompanied with a significant side effect profile. The recent development of targeted therapy, spearheaded by Teprotumumab has led to an array of treatments focusing on specific components of the molecular pathway optimising their impact whilst possibly minimising their side effect profile. Future challenges involve identifying the most effective target for each patient rather than any single agent being a panacea. Long-term safety profiles will require clarification as unintended immunological consequence downstream may become manifest as seen in other diseases. Finally, future novel therapeutics will entail significant expenditure and may lead to a divergence of available treatment modalities between healthcare systems due to funding disparities.

An integrated methodology for quality assessment of therapeutic antibodies with potential long circulation half-life in harvested cell culture fluid using FcRn immobilized hydrophilic magnetic graphene

Designing modified therapeutic antibodies with enhanced FcRn-binding affinity holds promise in the extension of circulation half-lives and potential refinement of pharmacokinetics. During the development of these new-generation therapeutic antibodies, FcRn binding affinity of IgGs is emphasized and monitored as a critical quality attribute (CQA), alongside other critical assessments including titer and aggregation level. However, the traditional workflow for assessing the overall quality of expressed IgGs in harvested cell culture fluid (HCCF) is blamed to be cumbersome and time-consuming. This study presents an integrated methodology for the rapid quality assessment of IgGs in HCCF by selectively extracting IgGs with favorable high FcRn affinity for subsequent analysis using size exclusion chromatography (SEC). The approach utilizes innovative adsorbents known as FcRn immobilized hydrophilic magnetic graphene (MG@PDA@PAMAM-FcRn) in a magnetic solid-phase extraction (MSPE) process. To simulate the in vivo binding dynamics, MSPE binding and dissociation was performed at pH 6.0 and 7.4, respectively. The composite have demonstrated enhanced extraction efficiency and impurity removal ability in comparison to commercially available magnetic beads. The SEC monomer peak area value provides the output of this method, the ranking of which enabled the facile identification of superior HCCF samples with high overall quality of IgG. Optimization of MSPE parameters was performed, and the method was validated for specificity, precision, sensitivity, and accuracy. The proposed method exhibited an analytical time of 0.6 h, which is 7-22 times shortened in comparison to the conventional workflow.

Identification of Four Mouse FcRn Splice Variants and FcRn-Specific Vesicles

Research into the neonatal Fc receptor (FcRn) has increased dramatically ever since Simister and Mostov first purified a rat version of the receptor. Over the years, FcRn has been shown to function not only as a receptor that transfers immunity from mother to fetus but also performs an array of different functions that include transport and recycling of immunoglobulins and albumin in the adult. Due to its important cellular roles, several clinical trials have been designed to either inhibit/enhance FcRn function or develop of non-invasive therapeutic delivery system such as fusion of drugs to IgG Fc or albumin to enhance delivery inside the cells. Here, we report the accidental identification of several FcRn alternatively spliced variants in both mouse and human cells. The four new mouse splice variants are capable of binding immunoglobulins' Fc and Fab portions. In addition, we have identified FcRn-specific vesicles in which immunoglobulins and albumin can be stored and that are involved in the endosomal-lysosomal system. The complexity of FcRn functions offers significant potential to design and develop novel and targeted therapeutics.

Promising therapies for the treatment of myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) is an autoimmune condition targeting the neuromuscular junction, which manifests with neuromuscular symptoms of varying severity and significant morbidity. The mainstay of treatment in MG is mitigation of the immune cascade with steroids and non-steroidal immunosuppressive therapies. The therapeutic strategies in MG are transitioning from broad and indiscriminate immunosuppression to novel agents targeting key steps in MG pathogenesis, including T cell activation, B cell proliferation, complement activation, maintenance of pathogenic antibody production, and proinflammatory cytokine production.

AREAS COVERED

In this review, an overview of the pathogenesis of MG and traditional MG therapies is presented, followed by a discussion of the novel MG drugs that have been evaluated in phase 3 clinical trials with an emphasis on those which have received regulatory approval.

EXPERT OPINION

Novel MG therapeutics belonging to the classes of complement inhibitors, neonatal Fc receptor (FcRn) inhibitors and B cell depletors, as well as the other emerging MG drugs in the pipeline constitute promising treatment strategies with potentially better efficacy and safety compared to the conventional MG treatments. However, further long-term research is needed in order to optimize the implementation of these new treatment options for the appropriate patient populations.

Immune-Mediated Necrotizing Myopathy (IMNM): A Story of Antibodies

Immune-mediated necrotizing myopathy (IMNM) is a rare and severe disease that corresponds to a specific entity of idiopathic inflammatory myopathy. Patients with IMNM suffer from proximal muscle weakness, and present high levels of creatine kinase and necrotic myofibers. Anti-Signal Recognition Particle (SRP) and anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase autoantibodies (HMGCR) have recently been identified in two thirds of patients with IMNM and are used as a hallmark of the disease. In this review, we provide a detailed description of these antibodies and the tests used to detect them in the serum of patients. Based on in vitro studies and mouse models of IMNM, we discuss the role of autoantibodies in the pathogenesis of the disease. Finally, in the light of the latest knowledge, we conclude with a review of recent therapeutic approaches in IMNM.

Treatment of neuromyelitis optica spectrum disorder: revisiting the complement system and other aspects of pathogenesis

Neuromyelitis optica spectrum disorder (NMOSD) represents a rare neuroimmunological disease causing recurrent attacks and accumulation of permanent disability in affected patients. The discovery of the pathogenic IgG‑1 antibody targeting a water channel expressed in astrocytes, aquaporin 4, constitutes a milestone achievement. Subsequently, multiple pathophysiological aspects of this distinct disease entity have been investigated. Demyelinating lesions and axonal damage ensue from autoantibodies targeting an astroglial epitope. This conundrum has been addressed in the current disease model, where activation of the complement system as well as B cells and interleukin 6 (IL-6) emerged as key contributors. It is the aim of this review to address these factors in light of novel treatment compounds which reflect these pathophysiological concepts in aiming for attack prevention, thus reducing disease burden in patients with NMOSD.

Idiopathic inflammatory myopathies: current insights and future frontiers

Idiopathic inflammatory myopathies are a group of autoimmune diseases with a broad spectrum of clinical presentations, primarily characterised by immune-mediated muscle injury. Until recently, there was little insight into the pathogenesis of idiopathic inflammatory myopathies, which challenged the recognition of the breadth of heterogeneity of this group of diseases as well as the development of new therapeutics. However, the landscape of idiopathic inflammatory myopathies is evolving. In the past decade, advances in diagnostic tools have facilitated an enhanced understanding of the underlying disease mechanisms in idiopathic inflammatory myopathies, enabling the expansion of therapeutic trials. The fields of transcriptomics, prot§eomics, and machine learning offer the potential to gain greater insights into the underlying pathophysiology of idiopathic inflammatory myopathies. Harnessing insights gained from these sophisticated tools could contribute to the identification of differences at a molecular level among patients, accelerating the development of targeted, tailored therapies. Bolstered by the validation and standardisation of robust outcome measures, many promising therapies are in clinical trial development. Although challenges remain, there is great optimism in the field due to the progress in innovative diagnostics, outcome measures, and therapeutic approaches. In this Review, we discuss the expanding landscape of idiopathic inflammatory myopathies as the frontier of precision medicine becomes imminent.

Pharmacokinetics and pharmacodynamics across infusion rates of intravenously administered nipocalimab: results of a phase 1, placebo-controlled study

Introduction

Nipocalimab is a high-affinity, fully human, aglycosylated, effectorless, immunoglobulin G (IgG) 1 monoclonal antibody that targets the neonatal Fc receptor (FcRn), decreases systemic IgG including autoantibodies, and is under development in several IgG autoantibody- and alloantibody-mediated diseases, including generalized myasthenia gravis, chronic inflammatory demyelinating polyneuropathy, maternal-fetal medicine, and multiple other therapeutic areas. An initial phase 1 study with single and multiple ascending doses of nipocalimab infused intravenously (IV) over 2 h demonstrated dose-dependent serum pharmacokinetics and IgG reductions, with an adverse event (AE) profile comparable to placebo.

Methods

The current investigation evaluates the safety, tolerability, pharmacokinetics, and pharmacodynamics of single doses of nipocalimab across various IV infusion rates in a randomized, double-blind, placebo-controlled, sequential-dose study. Forty participants were randomized to receive nipocalimab 30 mg/kg over 60, 30, 15 or 7.5 min (0.5, 1, 2, or 4 mg/kg/min); nipocalimab 60 mg/kg over 15 min (4 mg/kg/min); or matching placebo.

Results

At doses up to 60 mg/kg and infusion rates up to 4 mg/kg/min (maximum clinically feasible rate), single doses of nipocalimab were tolerable, with 12 (40%) participants experiencing AEs across nipocalimab cohorts compared with 1 (10%) participant in the placebo cohort. AEs deemed treatment related occurred in 6 (20%) participants receiving nipocalimab and 1 (10%) participant receiving placebo. None of the AEs were severe, and no participants discontinued treatment due to AEs. Nipocalimab provided consistent, dose-dependent serum pharmacokinetics and IgG reductions, regardless of infusion rate.

Discussion

This study supports the use of shortened durations of nipocalimab infusion for future studies.

Bullous pemphigoid induced by IgG targeting type XVII collagen non-NC16A/NC15A extracellular domains is driven by Fc gamma receptor- and complement-mediated effector mechanisms and is ameliorated by neonatal Fc receptor blockade

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by autoantibodies targeting type XVII collagen (Col17) with the noncollagenous 16A (NC16A) ectodomain representing the immunodominant site. The role of additional extracellular targets of Col17 outside NC16A has not been unequivocally demonstrated. In this study, we showed that Col17 ectodomain-reactive patient sera depleted in NC16A IgG induced dermal-epidermal separation in a cryosection model indicating the pathogenic potential of anti-Col17 non-NC16A extracellular IgG. Moreover, injection of IgG targeting the murine Col17 NC14-1 domains (downstream of NC15A, the murine homologue of human NC16A) into C57BL/6J mice resulted in erythematous skin lesions and erosions. Clinical findings were accompanied by IgG/C3 deposits along the basement membrane and subepidermal blistering with inflammatory infiltrates. Disease development was significantly reduced in either Fc-gamma receptor (FcγR)- or complement-5a receptor-1 (C5aR1)-deficient mice. Inhibition of the neonatal FcR (FcRn), an atypical FcγR regulating IgG homeostasis, with the murine Fc fragment IgG2c-ABDEG, a derivative of efgartigimod, reduced anti-NC14-1 IgG levels, resulting in ameliorated skin inflammation compared with isotype-treated controls. These data demonstrate that the pathogenic effects of IgG targeting the Col17 domain outside human NC16A/murine NC15A are partly attributable to antibody-mediated FcγR- and C5aR1 effector mechanisms while pharmacological inhibition of the FcRn represents a promising treatment for BP. The mouse model of BP will be instrumental in further investigating the role of Col17 non-NC16A/NC15A extracellular epitopes and validating new therapies for this disease. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Batoclimab as induction and maintenance therapy in patients with myasthenia gravis: rationale and study design of a phase 3 clinical trial

Introduction

Batoclimab, a fully human monoclonal antibody that inhibits the neonatal fragment crystallisable receptor, has shown promising phase 2 clinical trial results in patients with generalised myasthenia gravis (gMG).

Methods and analysis

In this phase 3, randomised, quadruple-blind, placebo-controlled study, adults with gMG will be randomised 1:1:1 to induction therapy with batoclimab 680 mg, batoclimab 340 mg, or placebo, administered once weekly (QW) for 12 weeks as a subcutaneous injection. The primary endpoint is the change from baseline to week 12 on the Myasthenia Gravis Activities of Daily Living (MG-ADL) score. Batoclimab-treated patients achieving a ≥2-point improvement from baseline on MG-ADL at week 10 or week 12 will be re-randomised to maintenance treatment with batoclimab 340 mg QW, batoclimab 340 mg every other week (Q2W), or placebo for 12 weeks; batoclimab-treated patients with a <2-point improvement at week 10 and week 12 will be switched to placebo for the maintenance period and discontinued thereafter. Placebo-treated patients from the induction period will be re-randomised to batoclimab 340 mg QW or Q2W in the maintenance period. All patients who complete the maintenance period and achieve a ≥2-point improvement from baseline in MG-ADL during ≥1 of the final 2 visits of the induction and/or maintenance periods will continue their current batoclimab dose (or switch to batoclimab 340 mg QW for those on placebo) for a 52-week long-term extension (LTE-1). Patients who complete LTE-1 may enter a second, optional 52-week LTE (LTE-2).

Ethics and dissemination

This trial is being conducted in accordance with the International Council for Harmonisation Guideline for Good Clinical Practice, the Declaration of Helsinki, and each site's Institutional Review Board/Independent Ethics Committee. All patients must provide written informed consent. Results from this study will be published in peer-reviewed journals and presented at national and global conferences.

Trial registration number

NCT05403541.

Therapeutic Plasma Exchange Versus FcRn Inhibition in Autoimmune Disease

Therapeutic plasma exchange (TPE or PLEX) is used in a broad range of autoimmune diseases, with the goal of removing autoantibodies from the circulation. A newer approach for the selective removal of immunoglobulin G (IgG) antibodies is the use of therapeutic molecules targeting the neonatal Fc receptor (FcRn). FcRn regulates IgG recycling, and its inhibition results in a marked decrease in circulating autoantibodies of the IgG subtype. The difference between FcRn inhibition and PLEX is often questioned. With anti-FcRn monoclonal antibodies (mAbs) and fragments only recently entering this space, limited data are available regarding long-term efficacy and safety. However, the biology of FcRn is well understood, and mounting evidence regarding the efficacy, safety, and potential differences among compounds in development is available, allowing us to compare against nonselective plasma protein depletion methods such as PLEX. FcRn inhibitors may have distinct advantages and disadvantages over PLEX in certain scenarios. Use of PLEX is preferred over FcRn inhibition where removal of antibodies other than IgG or when concomitant repletion of missing plasma proteins is needed for therapeutic benefit. Also, FcRn targeting has not yet been studied for use in acute flares or crisis states of IgG-mediated diseases. Compared with PLEX, FcRn inhibition is associated with less invasive access requirements, more specific removal of IgG versus other immunoglobulins without a broad impact on circulating proteins, and any impacts on other therapeutic drug levels are restricted to other mAbs. In addition, the degree of IgG reduction is similar with FcRn inhibitors compared with that afforded by PLEX. Here we describe the scientific literature regarding the use of PLEX and FcRn inhibitors in autoimmune diseases and provide an expert discussion around the potential benefits of these options in varying clinical conditions and scenarios.

Subcutaneous batoclimab in generalized myasthenia gravis: Results from a Phase 2a trial with an open-label extension

OBJECTIVES

To assess the safety, tolerability, and key pharmacodynamic effects of subcutaneous batoclimab, a fully human anti-neonatal Fc receptor monoclonal antibody, in patients with generalized myasthenia gravis and anti-acetylcholine receptor antibodies.

METHODS

A Phase 2a, proof-of-concept, randomized, double-blind, placebo-controlled trial is described. Eligible patients were randomized (1:1:1) to receive once-weekly subcutaneous injections of batoclimab 340 mg, batoclimab 680 mg, or matching placebo for 6 weeks. Subsequently, all patients could enter an open-label extension study where they received batoclimab 340 mg once every 2 weeks for 6 weeks. Primary endpoints were safety, tolerability, and change from baseline in total immunoglobulin G, immunoglobulin G subclasses, and anti-acetylcholine receptor antibodies at 6 weeks post-baseline. Secondary endpoints included changes from baseline to 6 weeks post-baseline for Myasthenia Gravis Activities of Daily Living, Quantitative Myasthenia Gravis, Myasthenia Gravis Composite, and revised 15-item Myasthenia Gravis Quality of Life scores.

RESULTS

Seventeen patients were randomized to batoclimab 680 mg (n = 6), batoclimab 340 mg (n = 5), or placebo (n = 6). Batoclimab was associated with significantly greater reductions in total immunoglobulin G and anti-acetylcholine receptor antibodies from baseline to 6 weeks post-baseline than placebo. Reductions in immunoglobulin G subclasses were generally consistent with total immunoglobulin G. While clinical measures showed directionally favorable improvements over time, the study was not powered to draw conclusions about therapeutic efficacy. No safety issues were identified.

INTERPRETATION

The safety profile, pharmacodynamics, and preliminary clinical benefits observed in this study support further investigation of subcutaneous batoclimab injections as a potential patient-administered therapy for seropositive generalized myasthenia gravis.

Monoclonal antibody therapies for aquaporin-4-immunoglobulin G-positive neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody-associated disease

Monoclonal antibody therapies mark the new era of targeted treatment for relapse prevention in aquaporin-4 (AQP4)-immunoglobulin G (IgG)-positive neuromyelitis optica spectrum disorder (AQP4-IgG+NMOSD). For over a decade, rituximab, an anti-CD20 B-cell-depleting agent, had been the most effectiveness treatment for AQP4-IgG+NMOSD. Tocilizumab, an anti-interleukin-6 receptor, was also observed to be effective. In 2019, several randomized, placebo-controlled trials were completed that demonstrated the remarkable efficacy of eculizumab (anti-C5 complement inhibitor), inebilizumab (anti-CD19 B-cell-depleting agent), and satralizumab (anti-interleukin-6 receptor), leading to the Food and Drug Administration (FDA) approval of specific treatments for AQP4-IgG+NMOSD for the first time. Most recently, ravulizumab (anti-C5 complement inhibitor) was also shown to be highly efficacious in an open-label, external-controlled trial. Although only some patients with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) warrant immunotherapy, there is currently no FDA-approved treatment for relapse prevention in MOGAD. Observational studies showed that tocilizumab was associated with a decrease in relapses, whereas rituximab seemed to have less robust effectiveness in MOGAD compared to AQP4-IgG+NMOSD. Herein, we review the evidence on the efficacy and safety of each monoclonal antibody therapy used in AQP4-IgG+NMOSD and MOGAD, including special considerations in children and women of childbearing potential.

Therapeutic tactics for targeting B lymphocytes in autoimmunity and cancer

B lymphocytes have become a very popular therapeutic target in a number of autoimmune indications due to their newly appreciated roles, and approachability, in these diseases. Many of the therapies now applied in autoimmunity were initially developed to deplete malignant B cells. These strategies have also been found to benefit patients suffering from such autoimmune diseases as multiple sclerosis, type I diabetes, systemic lupus erythematosus, and rheumatoid arthritis, to name a few. These observations have supported the expansion of research addressing the mechanistic contributions of B cells in these diseases, as well as blossoming of therapeutics that target them. This review seeks to summarize cutting-edge modalities for targeting B cells, including monoclonal antibodies, bispecific antibodies, antibody-drug conjugates, chimeric antigen receptor-T cells, and small molecule inhibitors. Efforts to refine B-cell targeted therapy to eliminate only pathogenic autoreactive cells will be addressed as well as the potential for future B-cell-based cellular therapeutics. Finally, we also address approaches that seek to silence B-cell function without depletion.

Exploiting the neonatal crystallizable fragment receptor to treat kidney disease

The neonatal Fc receptor (FcRn) was initially discovered as the receptor that allowed passive immunity in newborns by transporting maternal IgG through the placenta and enterocytes. Since its initial discovery, FcRn has been found to exist throughout all stages of life and in many different cell types. Beyond passive immunity, FcRn is necessary for intrinsic albumin and IgG recycling and is important for antigen processing and presentation. Given its multiple important roles, FcRn has been utilized in many disease treatments including a new class of agents that were developed to inhibit FcRn for treatment of a variety of autoimmune diseases. Certain cell populations within the kidney also express high levels of this receptor. Specifically, podocytes, proximal tubule epithelial cells, and vascular endothelial cells have been found to utilize FcRn. In this review, we summarize what is known about FcRn and its function within the kidney. We also discuss how FcRn has been used for therapeutic benefit, including how newer FcRn inhibiting agents are being used to treat autoimmune diseases. Lastly, we will discuss what renal diseases may respond to FcRn inhibitors and how further work studying FcRn within the kidney may lead to therapies for kidney diseases.

Proof-of-concept and Randomized, Placebo-controlled Trials of an FcRn Inhibitor, Batoclimab, for Thyroid Eye Disease

CONTEXT

Inhibition of the neonatal fragment crystallizable receptor (FcRn) reduces pathogenic thyrotropin receptor antibodies (TSH-R-Ab) that drive pathology in thyroid eye disease (TED).

OBJECTIVE

We report the first clinical studies of an FcRn inhibitor, batoclimab, in TED.

DESIGN

Proof-of-concept (POC) and randomized, double-blind placebo-controlled trials.

SETTING

Multicenter.

PARTICIPANTS

Patients with moderate-to-severe, active TED.

INTERVENTION

In the POC trial, patients received weekly subcutaneous injections of batoclimab 680 mg for 2 weeks, followed by 340 mg for 4 weeks. In the double-blind trial, patients were randomized 2:2:1:2 to weekly batoclimab (680 mg, 340 mg, 255 mg) or placebo for 12 weeks.

MAIN OUTCOME

Change from baseline in serum anti-TSH-R-Ab and total IgG (POC); 12-week proptosis response (randomized trial).

RESULTS

The randomized trial was terminated because of an unanticipated increase in serum cholesterol; therefore, data from 65 of the planned 77 patients were analyzed. Both trials showed marked decreases in pathogenic anti-TSH-R-Ab and total IgG serum levels (P < .001) with batoclimab. In the randomized trial, there was no statistically significant difference with batoclimab vs placebo in proptosis response at 12 weeks, although significant differences were observed at several earlier timepoints. In addition, orbital muscle volume decreased (P < .03) at 12 weeks, whereas quality of life (appearance subscale) improved (P < .03) at 19 weeks in the 680-mg group. Batoclimab was generally well tolerated, with albumin reductions and increases in lipids that reversed upon discontinuation.

CONCLUSIONS

These results provide insight into the efficacy and safety of batoclimab and support its further investigation as a potential therapy for TED.

The evolution and heterogeneity of neutrophils in cancers: origins, subsets, functions, orchestrations and clinical applications

Neutrophils, the most prevalent innate immune cells in humans, have garnered significant attention in recent years due to their involvement in cancer progression. This comprehensive review aimed to elucidate the important roles and underlying mechanisms of neutrophils in cancer from the perspective of their whole life cycle, tracking them from development in the bone marrow to circulation and finally to the tumor microenvironment (TME). Based on an understanding of their heterogeneity, we described the relationship between abnormal neutrophils and clinical manifestations in cancer. Specifically, we explored the function, origin, and polarization of neutrophils within the TME. Furthermore, we also undertook an extensive analysis of the intricate relationship between neutrophils and clinical management, including neutrophil-based clinical treatment strategies. In conclusion, we firmly assert that directing future research endeavors towards comprehending the remarkable heterogeneity exhibited by neutrophils is of paramount importance.

The PID Odyssey 2030: outlooks, unmet needs, hurdles, and opportunities - proceedings from the IPOPI global multi-stakeholders' summit (June 2022)

IPOPI held its first Global Multi-Stakeholders' Summit on 23-24 June 2022 in Cascais, Portugal. This IPOPI initiative was designed to set the stage for a stimulating forward-thinking meeting and brainstorming discussion among stakeholders on the future priorities of the PID community. All participants were actively engaged in the entire Summit, bringing provocative questions to ensure a high level of discussion and engagement, and partnered in identifying the outlooks, unmet needs, hurdles and opportunities of PIDs for 2030. The topics that were covered include diagnosis (e.g., newborn screening [NBS], genomic sequencing- including ethical aspects on the application of genomics on NBS, the role of more accurate and timely diagnostics in impacting personalized management), treatment (e.g., the therapeutic evolution of immunoglobulins in a global environment, new therapies such as targeted therapies, new approaches in curative therapies), the interactions of Primary ID with Secondary ID, Autoinflammatory Diseases and other diseases as the field experiences an incessant evolution, and also the avenues for research in the field of humanities and human sciences such as Patient-Reported Outcome Measures (PROMs), Patient-Reported Experience Measures (PREMs), and Health-Related Quality Of Life (HRQoL). During this meeting, all participants contributed to the drafting of recommendations based on our common understanding of the future opportunities, challenges, and scenarios. As a collection of materials, perspectives and summaries, they are succinct and impactful and may help determine some of the next key steps for the PID community.

A low dose of RBD and TLR7/8 agonist displayed on influenza virosome particles protects rhesus macaque against SARS-CoV-2 challenge

Influenza virosomes serve as antigen delivery vehicles and pre-existing immunity toward influenza improves the immune responses toward antigens. Here, vaccine efficacy was evaluated in non-human primates with a COVID-19 virosome-based vaccine containing a low dose of RBD protein (15 µg) and the adjuvant 3M-052 (1 µg), displayed together on virosomes. Vaccinated animals (n = 6) received two intramuscular administrations at week 0 and 4 and challenged with SARS-CoV-2 at week 8, together with unvaccinated control animals (n = 4). The vaccine was safe and well tolerated and serum RBD IgG antibodies were induced in all animals and in the nasal washes and bronchoalveolar lavages in the three youngest animals. All control animals became strongly sgRNA positive in BAL, while all vaccinated animals were protected, although the oldest vaccinated animal (V1) was transiently weakly positive. The three youngest animals had also no detectable sgRNA in nasal wash and throat. Cross-strain serum neutralizing antibodies toward Wuhan-like, Alpha, Beta, and Delta viruses were observed in animals with the highest serum titers. Pro-inflammatory cytokines IL-8, CXCL-10 and IL-6 were increased in BALs of infected control animals but not in vaccinated animals. Virosomes-RBD/3M-052 prevented severe SARS-CoV-2, as shown by a lower total lung inflammatory pathology score than control animals.

Repurposing MS immunotherapies for CIDP and other autoimmune neuropathies: unfulfilled promise or efficient strategy?

Despite advances in the treatment of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and other common autoimmune neuropathies (AN), still-many patients with these diseases do not respond satisfactorily to the available treatments. Repurposing of disease-modifying therapies (DMTs) from other autoimmune conditions, particularly multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD), is a promising strategy that may accelerate the establishment of novel treatment choices for AN. This approach appears attractive due to homologies in the pathogenesis of these diseases and the extensive post-marketing experience that has been gathered from treating MS and NMOSD patients. The idea is also strengthened by a number of studies that explored the efficacy of DMTs in animal models of AN but also in some CIDP patients. We here review the available preclinical and clinical data of approved MS therapeutics in terms of their applicability to AN, especially CIDP. Promising therapeutic approaches appear to be B cell-directed and complement-targeting strategies, such as anti-CD20/anti-CD19 agents, Bruton's tyrosine kinase inhibitors and anti-C5 agents, as they exert their effects in the periphery. This is a major advantage because, in contrast to MS, their action in the periphery is sufficient to exert significant immunomodulation.

Knowledge mapping of global trends for myasthenia gravis development: A bibliometrics analysis

Background

Myasthenia gravis (MG) is an autoimmune disease with acquired neuromuscular junction transmission disorders. In the last two decades, various pathogenesis, application of immunosuppressive agents, and targeted immunotherapy have been significant events. However, extracting the most critical information from complex events is very difficult to guide clinical work. Therefore, we used bibliometrics to summarize and look forward.

Methods

Science Citation Index Expanded (SCI-E) from the Web of Science Core Collection (WoSCC) database was identified as a source of material for obtaining MG-related articles. Scimago Graphica, CiteSpace, VOSviewer, and bibliometrix were utilized for bibliometric analysis. Knowledge network graphs were constructed and visualized; countries, institutions, authors, journals, references, and keywords were evaluated. In addition, GraphPad Prism and Microsoft Excel 365 were applied for statistical analysis.

Results

As of October 25, 2022, 9,970 original MG-related articles were used for the bibliometric analysis; the cumulative number of citations to these articles was 236,987, with an H-index of 201. The United States ranked first in terms of the number of publications (2,877) and H-index (134). Oxford has the highest H-index (67), and Udice French Research University has the highest number of publications (319). The author with the highest average number of citations (66.19), publications (151), and H-index (53) was Vincent A. 28 articles have remained in an explosive period of citations. The final screening yielded predictive keywords related to clinical trials and COVID-19.

Conclusion

We conducted a bibliometric analysis of 9,970 original MG-related articles published between 1966 and 2022. Ultimately, we found that future MG research hotspots include two major parts: (1) studies directly related to MG disease itself: clinical trials of various targeted biological agents; the relationship between biomarkers and therapeutic decisions, pathogenesis and outcome events, ultimately serving individualized management or precision therapy; (2) studies related to MG and COVID-19: different variants of COVID-19 (e.g., Omicron) on MG adverse outcome events; assessment of the safety of different COVID-19 vaccines for different subtypes of MG.

IgG4-related disease presenting with profound bilateral orbital and adnexal inflammation

Purpose

IgG4-related disease is an immune-mediated fibroinflammatory condition that can affect almost every major organ system. Orbital and adnexal involvement in IgG4-related disease though not uncommon can be varied depending on the site of the lymphoplasmacytic infiltration. This case of profound bilateral orbital inflammation is presented to demonstrate the significant clinical manifestations of IgG4-related ophthalmic disease.

Observations

A 52-year-old man with a remote and seemingly unrelated history of lymphadenopathy presented to the Oculoplastics clinic with massive bilateral upper and lower lid swelling and induration. Hematologic testing demonstrated an elevation in serum IgG4 - a non-specific finding seen in various infectious, inflammatory, and malignant processes. Imaging demonstrated diffuse enlargement of orbital structures, including the lacrimal glands and extraocular muscles, as well as inflammatory changes of the adnexal and retrobulbar soft tissue. Orbital biopsy was required to confirm the diagnosis of IgG4-related ophthalmic disease.

Conclusions and Importance

IgG4-related ophthalmic disease presents with various non-specific clinical signs and symptoms. The most common presentations include dacryoadenitis, enlarged orbital nerves, and orbital fat involvement; however, the extent of involvement both locally and systemically varies greatly. Clinical findings and imaging are helpful in narrowing the differential diagnosis; however, biopsy for histopathologic examination is essential to confirm IgG4-related disease. Physicians must maintain a high level of suspicion for the disease for proper management.

Efgartigimod for generalized myasthenia gravis with or without anti-acetylcholine receptor antibodies: a worldwide and Japanese perspective

INTRODUCTION

The management of myasthenia gravis (MG) has been improved due to immunotherapy advances, but 20% of individuals with MG are refractory to the conventional therapy, and the need for novel biological drugs remains.

AREA COVERED

The Japanese clinical guidelines for MG published in May 2022 include the concept that treatment is often lifelong and should aim to maintain a sufficient quality of life and mental health. We provide an overview of the therapeutic strategy for generalized MG in Japan, in comparison with the international consensus. We summarize the clinical efficacy, safety, and tolerability of efgartigimod, the first approved anti-neonatal Fc receptor inhibitor for MG. A phase III study showed that efgartigimod was well-tolerated and efficacious in patients with generalized MG.

EXPERT OPINION

Efgartigimod is a promising biological drug for patients with moderate to severe generalized MG with or without anti-acetylcholine receptor antibodies in Japan.

Monoclonal Antibody Engineering and Design to Modulate FcRn Activities: A Comprehensive Review

Understanding the biological mechanisms underlying the pH-dependent nature of FcRn binding, as well as the various factors influencing the affinity to FcRn, was concurrent with the arrival of the first recombinant IgG monoclonal antibodies (mAbs) and IgG Fc-fusion proteins in clinical practice. IgG Fc–FcRn became a central subject of interest for the development of these drugs for the comfort of patients and good clinical responses. In this review, we describe (i) mAb mutations close to and outside the FcRn binding site, increasing the affinity for FcRn at acidic pH and leading to enhanced mAb half-life and biodistribution, and (ii) mAb mutations increasing the affinity for FcRn at acidic and neutral pH, blocking FcRn binding and resulting, in vivo, in endogenous IgG degradation. Mutations modifying FcRn binding are discussed in association with pH-dependent modulation of antigen binding and (iii) anti-FcRn mAbs, two of the latest innovations in anti-FcRn mAbs leading to endogenous IgG depletion. We discuss the pharmacological effects, the biological consequences, and advantages of targeting IgG–FcRn interactions and their application in human therapeutics.

Targeting neonatal Fc receptor: potential clinical applications in pregnancy

The neonatal Fc receptor (FcRn) plays an important role in the transfer of the immunoglobulin G isotype (IgG) from the mother to the fetus. FcRn expressed on endothelial cells also binds to IgG and albumin, regulating the circulating half-lives of these proteins. Alloimmune and autoimmune IgG antibodies have been implicated in various perinatal immune-mediated diseases. FcRn-mediated placental transfer of pathogenic antibodies can result in cell and tissue injury in the fetus and neonate, with devastating outcomes. Thus, blockade of FcRn may be an effective treatment strategy in managing these conditions and could additionally reduce the concentration of pathogenic antibodies in the maternal circulation by preventing IgG recycling. In this review, we discuss the biology of FcRn, the rationale and considerations for development of FcRn-blocking agents, and their potential clinical applications in various perinatal immune-mediated diseases. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Role of complement, anti-complement therapeutics, and other targeted immunotherapies in myasthenia gravis

INTRODUCTION

Several patients with myasthenia gravis (MG) do not adequately respond to available drugs or exhibit poor tolerance, necessitating the need for new therapies.

AREAS COVERED

The paper discusses the rapidly evolving target-specific immunotherapies that promise long-standing remissions in the management of MG. It is specifically focused on the role of complement, anti-complement therapeutics, and the anti-FcRn and B cell monoclonals.

EXPERT OPINION

Anti-AChR antibodies cause internalization of the receptors and activate complement leading to in situ MAC formation that damages the post-synaptic membrane of the neuromuscular junction. Inhibiting MAC formation by antibodies targeting key complements subcomponents is a reasonable therapeutic goal. Indeed, the anti-C5 monoclonal antibodies, Eculizumab, Ravulizumab, and Zilucoplan, have been successfully tested in MG with Eculizumab first and now Ravulizumab FDA-approved for refractory MG based on sustained long-term benefits. Among the biologics that inhibit FcRn, Efgartigimod caused rapid reduction of the circulating IgG in the lysosomes, and induced sustained clinical remission with good safety profile leading to FDA-approved indication. Anti-B cell agents, like Rituximab, can induce sustained long-term remissions, especially in IgG4 antibody-mediated Musk-MG, by targeting short-lived antibody-secreting plasmablasts. These biologics offer effective targeted immunotherapies with good tolerance promising to change the therapeutic algorithm in the chronic MG management.

TAX and HBZ: hFc Ɣ 1 proteins as targets for passive immunotherapy

Objective(s):

Human T leukemia virus type one (HTLV-1) causes two life-threatening diseases in around five percent of infected subjects, a T cell malignancy and a neurodegenerative disease. TAX and HBZ are the main virulence agents implicated in the manifestation of HTLV-1–associated diseases. Therefore, this study aims to produce these HTLV-1 factors as recombinant Fc fusion proteins to study the structures, their immunogenic properties as vaccines, and their capability to produce specific neutralization antibodies.

Materials and Methods:

TAX and HBZ sequences were chosen from the NCBI-nucleotide database, then designed as human Fc chimers and cloned into Pichia pastoris. Produced proteins were purified by HiTrap affinity chromatography and subcutaneously injected into rabbits. Rabbit Abs were purified by batch chromatography, and their neutralization activities for the HTLV-1-infected MT-2 cell line were assessed. Furthermore, the protective abilities of recombinant proteins were evaluated in Tax or HBZ immunized rabbits by MT-2 cell line inoculation and measurement of HTLV-1-proviral load.

Results:

Specific Abs against Tax and HBZ can eliminate 2 million MT-2 cells in 1/1000 dilution in vitro. In challenging assays, the immunization of the animals using Tax or HBZ had no protective activity as HTLV-1 PVL was still positive.

Conclusion:

The result suggests that recombinant TAX and HBZ: hFcγ1 proteins can produce a proper humoral immune response. Therefore, they could be considered a passive immunotherapy source for HTLV-1-associated diseases, while total TAX and HBZ proteins are unsuitable as HTLV-1 vaccine candidates.

Practical guidance for the diagnosis and management of secondary hypogammaglobulinemia: A Work Group Report of the AAAAI Primary Immunodeficiency and Altered Immune Response Committees

Secondary hypogammaglobulinemia (SHG) is characterized by reduced immunoglobulin levels due to acquired causes of decreased antibody production or increased antibody loss. Clarification regarding whether the hypogammaglobulinemia is secondary or primary is important because this has implications for evaluation and management. Prior receipt of immunosuppressive medications and/or presence of conditions associated with SHG development, including protein loss syndromes, are histories that raise suspicion for SHG. In patients with these histories, a thorough investigation of potential etiologies of SHG reviewed in this report is needed to devise an effective treatment plan focused on removal of iatrogenic causes (eg, discontinuation of an offending drug) or treatment of the underlying condition (eg, management of nephrotic syndrome). When iatrogenic causes cannot be removed or underlying conditions cannot be reversed, therapeutic options are not clearly delineated but include heightened monitoring for clinical infections, supportive antimicrobials, and in some cases, immunoglobulin replacement therapy. This report serves to summarize the existing literature regarding immunosuppressive medications and populations (autoimmune, neurologic, hematologic/oncologic, pulmonary, posttransplant, protein-losing) associated with SHG and highlights key areas for future investigation.

Therapeutic Effects of Batoclimab in Chinese Patients with Generalized Myasthenia Gravis: A Double-Blinded, Randomized, Placebo-Controlled Phase II Study

Introduction

We investigated the safety and explore potential efficacy of batoclimab administered subcutaneously in Chinese patients with generalized myasthenia gravis (gMG).

Methods

A randomized, double-blinded, placebo-controlled, parallel phase II study was conducted. First, in the double-blinded treatment period, eligible patients received batoclimab (680 mg), batoclimab (340 mg), or placebo on days 1, 8, 15, 22, 29, and 36. In the open-label treatment period, patients received batoclimab (340 mg) on days 50, 64, and 78. In the follow-up period, patients were examined on days 92, 106, and 120. The primary endpoint was Myasthenia Gravis Activities of Daily Living (MG-ADL) score change on day 43 from baseline.

Results

In total, 30 eligible patients were enrolled, with 11, 10, and 9 patients in the batoclimab 680 mg, batoclimab 340 mg, and placebo groups, respectively. MG-ADL score changes from baseline to day 43 were −2.2 ± 0.9, −4.7 ± 0.6, and −4.4 ± 1.0 in the placebo, batoclimab 340 mg, and 680 mg groups, respectively. Similar changes were observed in Quantitative Myasthenia Gravis, Myasthenia Gravis Composite, and 15-item Myasthenia Gravis Quality of Life scores in the placebo, batoclimab 340 mg, and 680 mg groups, respectively. The proportion of patients with clinically significant improvement on day 43 was higher in the batoclimab groups. On day 120, all four scales in the placebo group had more significant improvement compared with the batoclimab groups, with total serum IgG levels reaching a plateau. No death or treatment-emergent adverse events (TEAEs) led to study discontinuation.

Conclusion

Batoclimab is effective and safe in Chinese patients with gMG.

Trial Registration

This study was registered at ClinicalTrials.gov (NCT04346888) on 15 April 2020, with the first patient enrolled on 23 July 2020.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-022-00345-9.

Neonatal Fc Receptor-Targeted Therapies in Neurology

Autoantibodies are increasingly recognized for their pathogenic potential in a growing number of neurological diseases. While myasthenia gravis represents the prototypic antibody (Ab)-mediated neurological disease, many more disorders characterized by Abs targeting neuronal or glial antigens have been identified over the past two decades. Depletion of humoral immune components including immunoglobulin G (IgG) through plasma exchange or immunoadsorption is a successful therapeutic strategy in most of these disease conditions. The neonatal Fc receptor (FcRn), primarily expressed by endothelial and myeloid cells, facilitates IgG recycling and extends the half-life of IgG molecules. FcRn blockade prevents binding of endogenous IgG to FcRn, which forces these antibodies into lysosomal degradation, leading to IgG depletion. Enhancing the degradation of endogenous IgG by FcRn-targeted therapies proved to be a powerful therapeutic approach in patients with generalized MG and is currently being tested in clinical trials for several other neurological diseases including autoimmune encephalopathies, neuromyelitis optica spectrum disorders, and inflammatory neuropathies. This review illustrates mechanisms of FcRn-targeted therapies and appraises their potential to treat neurological diseases.

Current Treatment of Myasthenia Gravis

Myasthenia gravis (MG) is the most extensively studied antibody-mediated disease in humans. Substantial progress has been made in the treatment of MG in the last century, resulting in a change of its natural course from a disease with poor prognosis with a high mortality rate in the early 20th century to a treatable condition with a large proportion of patients attaining very good disease control. This review summarizes the current treatment options for MG, including non-immunosuppressive and immunosuppressive treatments, as well as thymectomy and targeted immunomodulatory drugs.

Advances and challenges in the treatment of myasthenia gravis

Myasthenia gravis (MG) is a chronic autoimmune disease with fluctuating muscle weakness and fatigability. Standard immunomodulatory treatment may fail to achieve sufficient improvement with minimal symptom expression or remission of myasthenic symptoms, despite adequate dosing and duration of treatment. Treatment-resistant MG poses a challenge for both patients and treating neurologists and requires new therapeutic approaches. The spectrum of upcoming immunotherapies that more specifically address distinct targets of the main immunological players in MG pathogenesis includes T-cell directed monoclonal antibodies that block the intracellular cascade associated with T-cell activation, monoclonal antibodies directed against key B-cell molecules, as well as monoclonal antibodies against the fragment crystallizable neonatal receptor (FcRn), cytokines and transmigration molecules, and also drugs that inhibit distinct elements of the complement system activated by the pathogenic MG antibodies. The review gives an overview on new drugs being evaluated in still ongoing or recently finished controlled clinical trials and drugs of potential benefit in MG due to their mechanisms of action and positive effects in other autoimmune disorders. Also, the challenges associated with the new therapeutic options are discussed briefly.

Thyroid eye disease: From pathogenesis to targeted therapies

Thyroid eye disease (TED) is the most common extrathyroidal manifestation of autoimmune Graves’ hyperthyroidism. TED is a debilitating and potentially blinding disease with unclear pathogenesis. Autoreactive inflammatory reactions targeting orbital fibroblasts (OFs) lead to the expansion of orbital adipose tissues and extraocular muscle swelling within the fixed bony orbit. There are many recent advances in the understating of molecular pathogenesis of TED. The production of autoantibodies to cross-linked thyroid-stimulating hormone receptor and insulin-like growth factor-1 receptor (IGF-1R) activates OFs to produce significant cytokines and chemokines and hyaluronan production and to induce adipocyte differentiation. In moderately severe active TED patients, multicenter clinical trials showed that inhibition of IGF-1R with teprotumumab was unprecedentedly effective with minimal side effects. The emergence of novel biologics resulted in a paradigm shift in the treatment of TED. We here review the literature on advances of pathogenesis of TED and promising therapeutic targets and drugs.

Molecular Therapy in Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune disorder caused by antibodies that act against the myoneural junction. Conventional immunosuppressants such as corticosteroids, azathioprine and mycophenolate are associated with long-term side effects and many patients do not achieve remission and may become refractory. Thus, there is an unmet need for target-specific therapies that act faster, have fewer side effects and lead to stable disease remission. However, many of the novel therapeutic agents being described are not meeting their primary endpoints. We reviewed the current status of novel immunotherapies for MG, their mechanisms of action, along with the side effect profiles. Fast onset of action, sustained disease remission and relatively low frequency of side effects of the new agents are attractive. However, the unknown long-term safety and high cost are precluding factors. Better preclinical studies and more randomized trials are needed before novel agents are routinely employed.

"Ways in which the neonatal Fc-receptor is involved in autoimmunity"

Since the neonatal IgG Fc receptor (FcRn) was discovered, its role has evolved from immunoglobulin recycling and biodistribution to antigen presentation and immune complex routing, bringing it to the center of both humoral and cellular immune responses. FcRn is thus involved in the pathophysiology of immune-related diseases such as cancer, infection, and autoimmune disorders. This review focuses on the role of FcRn in autoimmunity, based on the available data from both animal models and human studies. The knowledge concerning ways in which FcRn is involved in autoimmune response has led to the development of inhibitors for the treatment of autoimmune diseases, also described here. Up to date, the literature remains scarce, shedding light on the need for further studies to fully understand the various pathophysiological roles of this unique receptor.

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FcRn is an intracellular receptor with a key role in IgG and immune complex management.

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FcRn-targeting therapies are a promising way of treatment in antibodies mediated diseases.

Prevention of diabetes-associated fibrosis: Strategies in FcRn-targeted nanosystems for oral drug delivery

Diabetes mellitus is a chronic disease with an elevated risk of micro- and macrovascular complications, such as fibrosis. To prevent diabetes-associated fibrosis, the symptomatology of diabetes must be controlled, which is commonly done by subcutaneous injection of antidiabetic peptides. To minimize the pain and distress associated with such injections, there is an urgent need for non-invasive oral transmucosal drug delivery strategies. However, orally administered peptide-based drugs are exposed to harsh conditions in the gastrointestinal tract and poorly cross the selective intestinal epithelium. Thus, targeting of drugs to receptors expressed in epithelial cells, such as the neonatal Fc receptor (FcRn), may therefore enhance uptake and transport through mucosal barriers. This review compiles how in-depth studies of FcRn biology and engineering of receptor-binding molecules may pave the way for design of new classes of FcRn-targeted nanosystems. Tailored strategies may open new avenues for oral drug delivery and provide better treatment options for diabetes and, consequently, fibrosis prevention.