The therapeutic age of the neonatal Fc receptor

Nipocalimab, an immunoselective FcRn blocker that lowers IgG and has unique molecular properties

Nipocalimab is a human immunoglobulin G (IgG)1 monoclonal antibody that binds to the neonatal Fc receptor (FcRn) with high specificity and high affinity at both neutral (extracellular) and acidic (intracellular) pH, resulting in the reduction of circulating IgG levels, including those of pathogenic IgG antibodies. Here, we present the molecular, cellular, and nonclinical characteristics of nipocalimab that support the reported clinical pharmacology and potential clinical application in IgG-driven, autoantibody- and alloantibody-mediated diseases. The crystal structure of the nipocalimab antigen binding fragment (Fab)/FcRn complex reveals its binding to a unique epitope on the IgG binding site of FcRn that supports the observed pH-independent high-binding affinity to FcRn. Cell-based and in vivo studies demonstrate concentration/dose- and time-dependent FcRn occupancy and IgG reduction. Nipocalimab selectively reduces circulating IgG levels without detectable effects on other adaptive and innate immune functions. In vitro experiments and in vivo studies in mice and cynomolgus monkeys generated data that align with observations from clinical studies of nipocalimab in IgG autoantibody- and alloantibody-mediated diseases.

Targeting the Neonatal Fc Receptor in Autoimmune Diseases: Pipeline and Progress

Autoimmune diseases are highly prevalent and affect people at all ages, women more often than men. The most prominent immunological manifestation is the production of antibodies directed against self-antigens. In many cases, these antibodies (Abs) drive the pathogenesis by attacking the body's own healthy cells, causing serious health problems that may be life threatening. Most autoantibodies are of the immunoglobulin G (IgG) isotype, which has a long plasma half-life and potent effector functions. Thus, there is a need for specific treatment options that rapidly eliminate these pathogenic IgG auto-Abs. In this review, we discuss how the neonatal Fc receptor (FcRn) acts as a regulator of the high levels of not only IgG Abs, but also albumin, by rescuing both these soluble proteins from cellular catabolism, and how a molecular and cellular understanding of this complex biology has spurred an intense interest in the development of FcRn-targeting strategies for the treatment of IgG-driven autoimmune diseases. We find that this emerging therapeutic class demonstrates efficacy within several autoimmune diseases with distinct pathophysiology. This offers hope for both new therapeutic avenues for highly prevalent diseases currently treated by other means, and rare diseases with no approved therapies to date. In addition, we elaborate on studies that have led to approval of the first FcRn antagonists, the clinical progress and structural design of molecules in the pipeline, their position in the overall therapeutic landscape of autoimmunity, the design of next-generation antagonists as well as the use of this receptor-targeting principle for other therapeutic applications.

Current and emerging therapies for autoimmune encephalitis

INTRODUCTION

Autoimmune encephalitis (AIE) is an inflammatory neurological disorder often associated with autoantibodies targeting neural or glial antigens. Patients with AIE are often treated with immunotherapy, but multiple questions remain about the optimal treatment strategy for common AIE subtypes.

AREAS COVERED

The authors conducted a literature search of PubMed articles and Google Scholar articles using keywords 'autoimmune encephalitis,' 'anti-NMDA receptor encephalitis, 'LG1 encephalitis' from 2005 to 2024. This review briefly outlines the proposed pathophysiology of AIE with autoantibodies toward cell surface vs intracellular antigens. Next, the authors discuss treatments commonly used for AIE, and provide guidance on side effects and monitoring, and the evidence for treatment approaches for anti-NMDAr and LGI1 encephalitis is reviewed. In the final section, an overview of ongoing clinical trials and future therapies for AIE is provided.

EXPERT OPINION

Patients with AIE benefit from treatment with immunotherapy, but the evidence supporting specific treatment strategies is limited to observational studies. Successful clinical trials for AIE will provide new therapy options for patients, and the next generation of therapies may provide more targeted approaches to treating the condition.

Evaluation of focused ultrasound modulation of the blood-brain barrier in gray and white matter

RATIONALE

Focused ultrasound (FUS) in combination with intravenous microbubbles is being studied clinically for modulation of the blood-brain barrier. Contrast-enhanced MRI can be used to visualize the enhanced permeability resulting from the treatment. However, contrast enhancement in the white matter (WM) are inconsistently observed compared to the gray matter (GM). Intrinsic tissue differences are believed to result in reduced treatment efficacy and insufficient drug delivery to the WM. In this study we evaluate the deposition of MRI contrast and clinically relevant antineoplastics in GM and WM tissues following single and repeated FUS and microbubble treatments.

METHODS

The brains of Fischer-344 rats (n = 24) and Yorkshire pigs (n = 6) underwent FUS (rats: 580 kHz; pigs: 220 kHz) treatments targeting the internal capsule and thalamus, repeated at 30-min intervals. Definity microbubbles (rats: 20 μL/kg bolus; pigs: 4 μL/kg/5-min infusion) were administered intravenously for each sonication with MRI contrast to measure gadolinium-mediated signal change. Feedback-controlled algorithms were used to monitor treatments and modulate the pressure based on emitted microbubble signals to ensure safe and effective exposures. The delivery of methotrexate (MTX; 454.4 Da) and bevacizumab (BVZ; 149 kDa) was evaluated via immunofluorescence microscopy in rats, and respectively quantified via liquid chromatography mass spectrometry and enzyme-linked immunosorbent assay in pigs.

RESULTS

Repeated FUS exposures successfully increased the vascular permeability of both gray and white matter tissues to MRI contrast and drugs of both small and large molecular sizes. In rats, single treatments showed statistically significant higher enhancements in the GM (23.5 ± 4.3 %; WM: 4.68 ± 3.75 %), however following a second sonication there were no between-tissue differences (GM: 38.0 ± 6.4 %; WM: 34.0 ± 8.7 %). In pigs, the smaller focus size relative to the brain enabled separate targeting of GM vs WM and the treatment controller used higher average power level in the WM to achieve the same cavitation dose. This resulted in no difference in gray and white matter permeability levels (to both contrast and pharmacological agents) after a single sonication. Repeated treatments sustained MRI enhancements for a longer time and enhanced drug deposition (MTX increased 6.5 and 8.3 folds after single and repeated treatment; BVZ increased 6.8 and 20.4 folds respectively).

CONCLUSIONS

Feedback-controlled algorithms and the possibility to individually target gray and white matter highlighted the impact of tissue composition on treatment outcomes. Repeated FUS-mediated modulation of the brain microvasculature achieved higher levels of permeabilization to contrast and pharmacological agents in both gray and white matter.

Opportunities and insights from pharmaceutical companies on the current use of new approach methodologies in nonclinical safety assessment

Sharing New Approach Methodology (NAM)-based regulatory experiences is crucial for improving human risk assessment and reducing animal use in drug safety testing. To foster broader adoption, the Biotechnology Innovation Organization surveyed companies about NAM usage and collected case studies showcasing NAM-based regulatory filings for biotherapeutics, where NAMs replaced large animal studies for safety assessment. These scientifically justified approaches were generally accepted by global health authorities, particularly in the context of species relevance limitations, prior target modulation experience, and/or when addressing severe disease. Despite successes with NAM-based global regulatory filings, there are concerns from companies about global regulatory harmonization and clinical translatability. NAMs have the potential for greater uptake with enhanced guidance and industry-regulatory agency collaboration being key to their adoption.

Targeted immunotherapies for Graves' thyroidal & orbital diseases

Background

Graves' hyperthyroidism and its associated Graves' orbitopathy are common autoimmune disorders associated with significant adverse health impact. Current standard treatments have limitations regarding efficacy and safety, and most do not specifically target the pathogenic mechanisms. We aim to review the latest development of targeted immunotherapies in these two closely related disorders.

Summary

Targeted immunotherapies of Graves' hyperthyroidism have recently demonstrated clinical efficacy in early phase clinical studies. They include rituximab, an anti-CD20 monoclonal antibody which causes rapid B cell depletion; ATX-GD-59, an antigen specific immunotherapy which restores immune tolerance to thyrotropin receptor; iscalimab, an anti-CD40 monoclonal antibody which blocks the CD40-CD154 co-stimulatory pathway in B-T cell interaction; and K1-70, a thyrotropin receptor blocking monoclonal antibody. Furthermore, there have been major therapeutic advances in the management of Graves' orbitopathy. Mycophenolate has a dual mechanism of action both inhibiting the proliferation of activated B & T cells as well as the mammalian target of rapamycin growth intracellular pathway. Rituximab appears to be effective in active disease of recent onset without impending dysthyroid optic neuropathy. Both tocilizumab (anti-interleukin 6 receptor monoclonal antibody) and sirolimus (mammalian target of rapamycin inhibitor) showed promise in glucocorticoid resistant active disease. Teprotumumab, an anti-insulin-like growth factor-1 receptor monoclonal antibody, demonstrated remarkable all-round efficacy across a wide disease spectrum. Linsitinib, a dual small molecule inhibitor of insulin-like growth factor-1 receptor and insulin receptor, displayed significant proptosis reduction in its phase 2b/3 study. Finally, Batoclimab, an anti-neonatal fragment crystallizable receptor monoclonal antibody, which blocks recycling of pathogenic thyrotropin receptor antibody, showed promising signals for significant proptosis reduction, disease inactivation, overall response, and improvement of quality of life.

Conclusion

Therapeutic advances will continue to optimize our management of Graves' hyperthyroidism and its associated orbitopathy in an effective and safe manner.

FcRn-dependent IgG accumulation in adipose tissue unmasks obesity pathophysiology

Immunoglobulin G (IgG) is traditionally recognized as a plasma protein that neutralizes antigens for immune defense. However, our research demonstrates that IgG predominantly accumulates in adipose tissue during obesity development, triggering insulin resistance and macrophage infiltration. This accumulation is governed by neonatal Fc receptor (FcRn)-dependent recycling, orchestrated in adipose progenitor cells and macrophages during the early and late stages of diet-induced obesity (DIO), respectively. Targeting FcRn abolished IgG accumulation and rectified insulin resistance and metabolic degeneration in DIO. By integrating artificial intelligence (AI) modeling with in vivo and in vitro experimental models, we unexpectedly uncovered an interaction between IgG's Fc-CH3 domain and the insulin receptor's ectodomain. This interaction hinders insulin binding, consequently obstructing insulin signaling and adipocyte functions. These findings unveil adipose IgG accumulation as a driving force in obesity pathophysiology, providing a novel therapeutic strategy to tackle metabolic dysfunctions.

The Expanding Antineutrophil Cytoplasmic Antibody-Associated Vasculitis Armamentarium

The complex pathophysiology of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) is reflected in the heterogeneity of the presenting clinical syndromes caused by these diseases but also provides a variety of conceivable molecular and cellular targets that can be therapeutically manipulated. The last decade has seen an expansion of established and potential therapies for treating AAV, some of which target the dysfunctional autoreactive immune response and others aim to ameliorate the downstream consequences of local vascular inflammation and necrosis. The success and widespread adoption of the anti-CD20 monoclonal antibody, rituximab, as an agent to both induce and maintain remission, has heralded a change in the standard-of-care management of AAV, replacing the "old guard" combination of cyclophosphamide and high-dose corticosteroids established in the 1970s. The development and approval of avacopan, a first-in-class small-molecule antagonist to the main receptor for the complement anaphylatoxin C5a, has the potential to reduce the corticosteroid burden experienced by patients with AAV and may also improve outcomes for those with AAV kidney disease. It marks the culmination of almost 20 years of international collaboration, from understanding the pathological role of complement in basic murine models of AAV through to a phase III clinical trial, and emphasises the importance of following promising translational discoveries through to drug development and clinical deployment. This article summarises how recent progress in our understanding of the basic pathophysiology of AAV has resulted in the development of new and effective treatments and, reciprocally, how studying the impact of these treatments in patients has advanced our understanding of dysfunctional immunobiology in disease.

Evaluation of the effect of rozanolixizumab on pregnancy outcomes and pre- and postnatal development in cynomolgus monkeys

Rozanolixizumab, a humanised immunoglobulin (Ig) G4 monoclonal antibody that selectively inhibits binding of IgG to the neonatal Fc receptor (FcRn), was evaluated in an embryo-foetal enhanced pre- and postnatal development (ePPND) study. Pregnant female cynomolgus monkeys (19 per group) received subcutaneous rozanolixizumab 50 mg/kg or 150 mg/kg or vehicle every 3 days from gestation day 20 until delivery. The proportion of pregnancy losses was 15.8%, 21.1% and 5.3% in the rozanolixizumab 50 mg/kg, 150 mg/kg and control groups, respectively. Based on eNormograms for groups of 18 or 20 animals, these results were considered to be within the range of spontaneous prenatal losses naturally observed in cynomolgus monkeys. Foetal examinations revealed no treatment-related effects. All infants had normal postnatal development, although higher mortality was observed in female infants from the control group during the first 3 weeks. All infants were able to mount a normal immune response to keyhole limpet haemocyanin when vaccinated at the age of 4 months. Offspring from 150 mg/kg-treated mothers had very low IgG levels at birth, indicating blockade of maternal IgG transfer; infants from mothers who received 50 mg/kg had variable IgG levels at birth, with mothers who had developed significant anti-drug antibodies conferring maternal IgG transfer to varying degrees. Rates of infection in infants were similar across treatment groups. IgG levels in infants from rozanolixizumab-treated groups normalised within 2 months. Treatment of pregnant cynomolgus monkeys with the FcRn inhibitor rozanolixizumab had no adverse effects on pre- or postnatal development of offspring, including immune system development.

FcRn inhibitors: Transformative advances and significant impacts on IgG-mediated autoimmune diseases

Pathogenic IgG autoantibodies play a crucial role in the pathogenesis of autoimmune diseases, and removal of pathogenic IgG autoantibodies is an important therapeutic approach and tool for such diseases. The neonatal Fc receptor (FcRn) interacts with IgG and protects it from lysosomal degradation. FcRn inhibitors accelerate the clearance of IgG antibodies, including pathogenic IgG autoantibodies, by targeting and blocking the binding of FcRn to IgG. Theoretically, FcRn inhibitors can be applied for the treatment of IgG-mediated autoimmune diseases. With successful completion of multiple relevant clinical trials, key evidence-based data have been provided for FcRn inhibitors in the treatment of IgG-mediated autoimmune diseases, and several FcRn inhibitors have been approved for these indications. Additional trials are being planned or conducted. This review examines all available high-quality clinical trials of FcRn inhibitors assessing IgG-mediated autoimmune diseases.

Pharmacokinetic interaction assessment of an HIV broadly neutralizing monoclonal antibody VRC07-523LS: a cross-protocol analysis of three phase 1 trials in people without HIV

VRC07-523LS is a safe and well-tolerated monoclonal antibody (mAb) targeting the CD4 binding site on the HIV envelope (Env) trimer. Efficacy of VRC07-523LS, in combination with mAbs targeting other HIV epitopes, will be evaluated in upcoming trials to prevent HIV acquisition in adults. However, differences in the pharmacokinetics (PK) of VRC07-523LS when administered alone vs. in combination with other mAbs have not been formally assessed. We performed a cross-protocol analysis of three clinical trials and included data from a total of 146 adults without HIV who received intravenous (n = 95) or subcutaneous (n = 51) VRC07-523LS, either alone ('single'; n = 100) or in combination with 1 or 2 other mAbs ('combined'; n = 46). We used an open, two-compartment population PK model to describe serum concentrations of VRC07-523LS over time, accounting for inter-individual variabilities. We compared individual-level PK parameters between the combined vs. single groups using the targeted maximum likelihood estimation method to adjust for participant characteristics. No significant differences were observed in clearance rate, inter-compartmental clearance, distribution half-life, or total VRC07-523LS exposure over time. However, for the combined group, mean central volume of distribution, peripheral volume of distribution, and elimination half-life were slightly greater, corresponding to slightly lower predicted concentrations early post-administration with high levels being maintained in both groups. These results suggest potential PK interactions between VRC07-523LS and other mAbs, but with small clinical impact in the context of HIV prevention. Our findings support coadministration of VRC07-523LS with other mAbs, and the use of the developed PK models to design future trials for HIV prevention.

Small RNA and Toll-like receptor interactions: origins and disease mechanisms

Advances in small RNA sequencing have revealed diverse small noncoding RNAs (sncRNAs) beyond microRNAs (miRNAs), derived from transfer RNAs (tRNAs), ribosomal RNAs (rRNAs), small nuclear RNAs (snRNAs), and Y RNAs, carrying distinct RNA modifications. These emerging sncRNAs can function beyond RNA interference (RNAi), adopting aptamer-like roles by interacting with Toll-like receptors 7 and 8 (TLR7 and TLR8) via specific sequences, modifications, and structures. We propose a Sequential Activation Hypothesis where initial abnormal sncRNAs - triggered by infections or stresses - activate TLR7/8, leading to autoantibody production against autoantigens like RNA-binding proteins La and Ro. These autoantibody-antigen complexes further promote secondary immunogenic sncRNA production and repetitive TLR7/8 activation, perpetuating a vicious cycle sustaining autoimmunity. TLR7/8's X chromosome location and sex-biased expression contribute to female-dominant autoimmune diseases. Understanding sncRNA-TLR interactions is essential for designing novel therapeutic strategies.

Engineering cytokines for tumor-targeting and selective T cell activation

Cytokines are promising therapeutic agents for cancer due to their immune-stimulating properties. However, their clinical application is limited by a narrow therapeutic window and dose-limiting on-target, off-tumor toxicity. Advances in protein engineering enable the selective delivery of cytokines to the tumor microenvironment (TME) and antigen-specific T cells, enhancing antitumor efficacy while reducing systemic side effects. This review focuses on selected cytokines and outlines their developmental trajectory for treating solid tumors. We highlight strategies for constructing cis-signaling immunocytokines and procytokines for precise delivery to tumor sites and discuss the biological mechanisms through which these cytokines reactivate antitumor immunity. We also discuss the challenges and future directions for creating more effective cytokine-based therapeutics.

Monoclonal anti-CD38 therapy in human myeloma: retrospects and prospects

Monoclonal antibody therapy using CD38 as a target remains central to managing human multiple myeloma (MM). CD38 was selected early on as a target for mAb-mediated therapy for MM, driven by findings from an early Cluster of Differentiation (CD) Workshop. The first CD38-targeting antibody to be approved yielded strong trial results, significantly improving survival rates and earning widespread patient acceptance. However, resistance to the therapy later emerged, complicating treatment management. Despite CD38's still central role in MM therapy, too little attention has been paid to its broader roles-not only as a myeloma marker but also as an enzyme and adhesion molecule in physiology. This review, a collaborative effort between basic scientists and clinical experts, explores some of the lesser-known mechanisms of antibody action and interactions with CD38 at key stages of treatment. The review also highlights the relevance of the MM environment, focusing on the importance of the bone marrow (BM) niche. The goal is to identify new agents whose unique properties may enhance tumor eradication. By gaining a deeper understanding of interactions between therapeutic antibodies, myeloma cells, and the tumor microenvironment (TME), it is hoped that previously unrecognized vulnerabilities within the disease may be revealed, paving the way to more effective treatment strategies.

The neonatal Fc receptor (FcRn) is required for porcine reproductive and respiratory syndrome virus uncoating

Porcine reproductive and respiratory syndrome virus (PRRSV) continues to cause substantial economic losses to the pig industry worldwide. Previous studies from other groups showed that CD163 is required for PRRSV uncoating and genome release. However, CD163 does not interact with nucleocapsid (N) protein. In this study, the neonatal Fc receptor (FcRn) was demonstrated to be irreplaceable for PRRSV infection by knockdown, overexpression, antibodies or IgG blocking, knockout, and replenishment assays. FcRn was further revealed to be involved in PRRSV uncoating for the first time rather than viral attachment and internalization. In detail, FcRn was determined to colocalize with CD163 and PRRSV virions in early endosomes and specially interact with N protein in early endosomes. Taken together, these results provide evidence that FcRn is an essential cellular factor for PRRSV uncoating, which will be a promising target to interfere with the viral infection.IMPORTANCEPRRSV infection results in a severe swine disease affecting pig farming in the world. Although CD163 has been implicated as the uncoating receptor for PRRSV but the uncoating mechanism of PRRSV remains unclear. Here, we identified that FcRn facilitated virion uncoating via interaction with viral N protein in early endosomes. Our work actually expands the knowledge of PRRSV infection and provides an attractive therapeutic target for the prevention and control of PRRS.

Successful treatment with efgartigimod as an add-on therapy for acute attack of anti-NMDA receptor encephalitis: a case report

BACKGROUND

Anti-NMDA receptor encephalitis is an autoimmune, antibody-mediated inflammatory disease of the brain characterized by the presence of IgG antibodies targeting the excitatory N-methyl-D-aspartate receptor (NMDAR). Previous research has established that the neonatal Fc receptor (FcRn) regulates the transport and circulation of immunoglobulins (IgG). Efgartigimod, an FcRn antagonist, has been shown to enhance patient outcomes by promoting IgG clearance, and it has exhibited substantial clinical efficacy and tolerability in the treatment of myasthenia gravis. Efgartigimod has demonstrated potential efficacy in the treatment of various IgG-mediated autoimmune diseases. Nonetheless, to date, no studies have investigated the use of efgartigimod in the treatment of anti-NMDAR encephalitis.

CASE PRESENTATION

We present a case of a 42-year-old male patient diagnosed with anti-NMDAR encephalitis, initially treated with intravenous methylprednisolone(IVMP) and human immunoglobulin (IVIG) without clinical improvement. Subsequent administration of efgartigimod resulted in rapid clinical improvement; however, the patient experienced a relapse upon discontinuation of efgartigimod. Reintroduction of efgartigimod led to rapid and significant clinical improvement, accompanied by a marked decrease in anti-NMDAR antibodies and serum IgG levels in both serum and cerebrospinal fluid. The patient remained relapse-free during a 2-month follow-up period.

CONCLUSION

This case demonstrates that efgartigimod is a potentially rapid and effective therapy for the treatment of the acute phase of anti-NMDAR encephalitis.

The B-cells paradigm in systemic sclerosis: an update on pathophysiology and B-cell-targeted therapies

Systemic sclerosis (SSc) is considered a rare autoimmune disease in which there are alterations of both the innate and adaptive immune response resulting in the production of autoantibodies. Abnormalities of the immune system compromise the normal function of blood vessels leading to a vasculopathy manifested by Raynaud's phenomenon, an early sign of SSc . As a consequence of this reactive picture, the disease can evolve leading to tissue fibrosis. Several SSc-specific autoantibodies are currently known and are associated with specific clinical manifestations and prognosis. Although the pathogenetic role of these autoantibodies is still unclear, their production by B cells and plasma cells suggests the importance of these cells in the development of SSc. This review narratively examines B-cell dysfunctions and their role in the pathogenesis of SSc and discusses B-cell-targeted therapies currently used or potentially useful for the management of end-organ complications.

B Cell Responses to the Placenta and Fetus

Pregnancy has fascinated immunologists ever since Peter Medawar's observation that reproduction runs contrary to the founding tenets of immunology. During healthy pregnancy, maternal B cells interact with antigens of the foreign conceptus (placenta and fetus) yet do not elicit rejection. Instead, robust and redundant fetomaternal tolerance pathways generally prevent maternal B cells and antibodies from harming the placenta and fetus. Fetomaternal tolerance is not absolute, and unfortunately there exist several pregnancy complications that arise from breaks therein. Here, important historic and recent developments in the field of fetomaternal tolerance pertaining to maternal B cells and antibodies are reviewed. General rules from which to conceptualize humoral tolerance to the placenta and fetus are proposed. Significant but underexplored ideas are highlighted and topics for future research are suggested, findings from which are predicted to provide insight into the fundamental nature of tolerance and bolster efforts to combat immune-mediated pregnancy complications.

Strategies for extending the half-life of biotherapeutics: successes and complications

INTRODUCTION

Engineering of the drug half-life in vivo has become an integral part of modern biopharmaceutical development due to the fact that many proteins/peptides with therapeutic potential are quickly cleared by kidney filtration after injection and, thus, circulate only a few hours in humans (or just minutes in mice).

AREAS COVERED

Looking at the growing list of clinically approved biologics that have been modified for prolonged activity, and also the plethora of such drugs under preclinical and clinical development, it is evident that not one solution fits all needs, owing to the vastly different structural features and functional properties of the pharmacologically active entities. This article provides an overview of established half-life extension strategies, as well as of emerging novel concepts for extending the in vivo stability of biologicals, and their pros and cons.

EXPERT OPINION

Beyond the classical and still dominating technologies for improving drug pharmacokinetics and bioavailability, Fc fusion and PEGylation, various innovative approaches that offer advantages in different respects have entered the clinical stage. While the Fc fusion partner may be gradually superseded by engineered albumin-binding domains, chemical PEGylation may be replaced by biodegradable recombinant amino-acid polymers like PASylation, thus also offering a purely biotechnological manufacturing route.

Enhanced Gut-to-Liver Oral Drug Delivery via Ligand-Modified Nanoparticles by Attenuating Protein Corona Adsorption

The development of effective oral drug delivery systems for targeted gut-to-liver transport remains a significant challenge due to the multiple biological barriers including the harsh gastrointestinal tract (GIT) environment and the complex protein corona (PC) formation. In this study, we developed ligand-modified nanoparticles (NPs) that enable gut-to-liver drug delivery by crossing the GIT and attenuating PC formation. Specifically, mesoporous silica nanoparticles (MSNs) were functionalized with peptides targeting the neonatal Fc receptor (FcRn), capitalizing on FcRn expression in the small intestine and liver for targeted drug delivery. We showed that MSNs decorated with a small cyclic FcRn binding peptide (MSNs-FcBP) obtained enhanced diffusion in intestinal mucus and superior transportation across the intestine compared to unmodified MSNs and MSNs decorated with a large IgG Fc fragment (MSNs-Fc), which correlated with diminished protein adsorption and weaker interaction with mucin. After entering the blood circulation, reduced serum PC formation by MSNs-FcBP reduces the proteolytic and phagocytic propensity of the reticuloendothelial system, ultimately ameliorating accumulation in hepatocytes. Pharmacokinetic and pharmacodynamic studies in diabetic mice revealed that MSNs-FcBP effectively transported the therapeutic agent exenatide across the intestinal epithelium, leading to a significant hypoglycemic response and improved glucose tolerance. This study underscores the critical role of ligand selection in limiting protein corona formation, thereby significantly enhancing gut-to-liver drug delivery by increasing mucus permeation and minimizing serum-protein interactions. The effective delivery of exenatide in diabetic mice illustrates the potential of this strategy to optimize oral drug bioavailability and therapeutic efficacy.

Eculizumab in thymoma-associated myasthenia gravis: a real-world cohort study

Background

Thymoma-associated myasthenia gravis (TAMG) is a subtype of myasthenia gravis (MG) that is associated with more severe symptoms and a relatively poor prognosis. Eculizumab, an inhibitor to target human C5 component of the complement cascade, is considered a treatment option for refractory generalized MG (gMG).

Objectives

To explore the safety and efficacy of eculizumab in patients with TAMG.

Design

This is an observational multicenter real-world cohort study to assess TAMG who were treated with eculizumab from June 2023 to June 2024.

Data sources and methods

Clinical features associated with thymoma-associated multi-organ autoimmunity (TAMA), Myasthenia Gravis Activities of Daily Living (MG-ADL) score, and the incidence of treatment-emergent adverse events (TEAEs) were prospectively collected.

Results

Overall, 42 patients with gMG were treated with eculizumab at 5 research centers, of whom 22 patients with TAMG were finally included. This cohort had a mean age of 51.5 ± 12.1 years and an average disease duration of 4.0 ± 4.3 years. Regarding thymomas, the World Health Organization (WHO) histological classification was primarily B2 and B3 (63.7%), and Masaoka staging was predominantly IV (45.5%). Nine participants (40.9%) switched from efgartigimod to eculizumab aiming at a better clinical improvement and reducing steroid use. By week 12, the MG-ADL score decreased to 4.8 ± 4.7 (baseline: 11.7 ± 6.0), and the corticosteroid dose reduced to 23.2 ± 26.5 mg (baseline: 41.8 ± 63.9 mg). Two patients with TAMA showed significant improvement in skin lesions and thrombocytopenia. Two TEAEs were recorded including COVID-19 and herpes labialis infection. Four patients (18.2%) died of respiratory or circulatory failure owing to thymoma metastasis.

Conclusion

This real-world study demonstrates the efficacy of eculizumab in achieving symptom control and corticosteroid reduction for TAMG. It may also be a therapeutic option for refractory TAMG and TAMA.

Trial registration

NCT04535843.

Depemokimab, the first ultra-long-acting anti-IL-5 monoclonal antibody for severe eosinophilic asthma

Depemokimab, the first ultra-long-acting anti-IL-5 monoclonal antibody, significantly reduced exacerbation rates in patients with severe eosinophilic asthma when administered biannually.1 While it offers potential benefits for patient adherence and convenience, the trials showed no improvement in symptoms and lung function. Further research is needed to determine its optimal place in therapy and identify patients who will benefit the most.

A clinical perspective on muscle specific kinase antibody positive myasthenia gravis

The discovery of autoantibodies directed against muscle-specific kinase (MuSK) in "seronegative" myasthenia gravis (MG) patients marked a milestone in MG research. In healthy muscle, MuSK regulates a phosphorylation pathway, which is essential for the development and maintenance of acetylcholine receptor (AChR) clusters at the neuromuscular junction. Autoantibodies directed against MuSK are predominantly of the IgG4 subclass, but there is increasing evidence that IgG1-3 could also contribute to the pathology underlying MuSK-MG. MuSK-IgG4 are monovalent and block the binding site for LRP4 on MuSK, thereby inhibiting the downstream phosphorylation pathway and compromising the formation of AChR clusters. Clinically, MuSK-MG is commonly associated with the predominant involvement of bulbar, facial, shoulder and neck muscles. Cholinesterase inhibitors should be avoided in MuSK-MG due to the risk of clinical impairment and cholinergic crisis. Corticosteroids and other non-steroidal immunosuppressants are less effective with the need for higher doses and prolonged treatment. Rituximab, by contrast, has been shown to be particularly effective and is now often used early in the disease course. Its use is associated with a significant improvement in the clinical outcome of MuSK-MG patients over time. This review aims to describe the pathophysiology underlying MuSK-MG and provide a comprehensive overview of the clinical features and therapeutic options.

Mechanisms of Mt.b Ag85B-Fc fusion protein against allergic asthma in mice by intranasal immunization

Ag85B, the primary component of the Ag85 complex and an early secreted protein by Mycobacterium tuberculosis, has shown potential for the treatment of allergic asthma (AA) when used as a Fc-fusion protein. Administered via nasal immunization, Ag85B-Fc fusion protein significantly alleviated airway inflammation and reduced the proportions of some anaphylaxis related cells in lungs, with no significant histopathological injury to major organs in ovalbumin (OVA)-induced AA model mice. To investigate the underlying immune regulatory mechanisms of Ag85B protein, integrated proteomics and transcriptomics analyses were conducted, identifying the complement and coagulation cascades, and phagosomes as the two significantly enriched pathways at both gene and protein levels. Moreover, C3ar1 (C3aR1), Itgam (CD11b), Itgb2 (CD18), fgg (FGG), Cybb (CYBB), and Ncf4 (NCF4) were identified as core target factors that play a central role in allergic and asthmatic responses. Among them, C3aR1 and CR3 consisting of CD11b and CD18, are main complement receptors, indicating that Ag85B alleviated AA by regulating C3aR1- and CR3-mediated signal transduction. The validation results were consistent with the aforementioned findings. Overall, these results provide valuable insight into the application of mucosal immunotherapy in treatment of AA, positioning Ag85B-Fc fusion protein as a safe mucosal immunotherapeutic agent for AA.

Successful treatment with efgartigimod as an add-on therapy in acute attack of anti-AQP4 antibody-positive NMOSD: a case report

BACKGROUND

Neuromyelitis Optica Spectrum Disorder (NMOSD) is an autoimmune demyelinating disease characterized by recurrent myelitis and optic neuritis. It is associated with high rates of relapse and disability. The main treatment strategies for acute attacks include intravenous methylprednisolone pulse (IVMP) treatment and rescue treatment with plasma exchange (PLEX). Recently, the blockade of neonatal Fc receptor (FcRn)-IgG interaction has gained momentum as a therapeutic strategy. Efgartigimod, the first approved FcRn inhibitor for treating generalized myasthenia gravis, has shown impressive safety, efficacy, and tolerability, and is being regarded as "PLEX in a bottle".

CASE DESCRIPTION

We report a 65-year-old female patient who was diagnosed with anti-AQP4 antibody positive NMOSD. Add-on treatment with efgartigimod to IVMP and intravenous immunoglobulin (IVIG) at the second acute relapse showed favorable results.

CONCLUSION

This case suggests that efgartigimod is a potentially effective add-on therapy in acute attacks of AQP4-IgG-positive NMOSD.

Antigen-specific immunotherapy for platelet alloimmune disorders

Fetal/Neonatal Alloimmune Thrombocytopenia (FNAIT) is a significant hematologic disorder arising from maternal immune responses to fetal platelet alloantigens, predominantly Human Platelet Antigen (HPA)-1a. This review first describes the pathogenesis of FNAIT, highlighting the roles of HPA-specific antibodies, particularly HPA-1a, in causing severe thrombocytopenia and intracranial hemorrhage in affected neonates. Current management strategies, including intravenous immunoglobulin and investigational therapies like Nipocalimab, are evaluated for their efficacy and limitations. The review also discusses promising antigen-specific therapies, such as effector-silent monoclonal antibodies and innovative approaches targeting alloantibody-producing B cells. Additionally, the potential of Chimeric Autoantibody Receptor (CAAR) T cell therapy for selective elimination of pathogenic B cells is examined. The necessity for a prophylactic strategy similar to RhD immunoprophylaxis in preventing FNAIT is emphasized, along with the importance of identifying at-risk pregnancies. The development of renewable monoclonal antibodies and suitable animal models are critical steps toward effective prevention and treatment of this disorder.

Novel therapeutic approach for psoriasis: Upregulating FcRn to inhibit ferroptosis and alleviate lesional skin

Psoriasis, a chronic inflammatory skin disease, is characterized by complex immune dysregulation and oxidative stress responses. The neonatal Fc receptor (FcRn) plays a crucial role in the development of autoimmune diseases. Analysis of clinical psoriasis samples demonstrated a negative correlation between FcRn expression in skin lesions and disease severity. However, the role of FcRn in this process remains unclear. This study aimed to investigate the involvement of FcRn in the pathogenesis and progression of psoriasis. In an imiquimod (IMQ)-induced psoriasis-like mouse model, FcRn expression was significantly decreased in the lesional skin, and transcriptome sequencing of the skin revealed activation of the ferroptosis pathway in psoriasis. This led to the hypothesis that FcRn could potentially regulate ferroptosis via the signal transducer and activating transcription factor 3 (STAT3)/solute carrier family 7 member 11 (SLC7A11) axis. Further experiments showed exacerbated psoriasis-like lesional skin and ferroptosis in FcRn-knockout mice, whereas intervention with the ferroptosis inhibitor Fer-1 or STAT3 inhibitor Stattic alleviated these symptoms. Critical binding sites for the transcription factor STAT3 were identified in the SLC7A11 promoter region at positions -1185 and -564 using the luciferase reporter assays and chromatin immunoprecipitation. The administration of 1,4-naphthoquinone (NQ), an FcRn agonist, effectively alleviated psoriasis-like skin lesions by inhibiting ferroptosis. This study highlights the molecular mechanisms of action of FcRn in psoriasis and provides an experimental basis for the development of novel therapeutic strategies targeting FcRn.

Immunomodulatory and anti-inflammatory properties of immunoglobulin G antibodies

Antibodies provide an essential layer of protection from infection and reinfection with microbial pathogens. An impaired ability to produce antibodies results in immunodeficiency and necessitates the constant substitution with pooled serum antibodies from healthy donors. Among the five antibody isotypes in humans and mice, immunoglobulin G (IgG) antibodies are the most potent anti-microbial antibody isotype due to their long half-life, their ability to penetrate almost all tissues and due to their ability to trigger a wide variety of effector functions. Of note, individuals suffering from IgG deficiency frequently produce self-reactive antibodies, suggesting that a normal serum IgG level also may contribute to maintaining self-tolerance. Indeed, the substitution of immunodeficient patients with pooled serum IgG fractions from healthy donors, also referred to as intravenous immunoglobulin G (IVIg) therapy, not only protects the patient from infection but also diminishes autoantibody induced pathology, providing more direct evidence that IgG antibodies play an active role in maintaining tolerance during the steady state and during resolution of inflammation. The aim of this review is to discuss different conceptual models that may explain how serum IgG or IVIg can contribute to maintaining a balanced immune response. We will focus on pathways depending on the IgG fragment crystallizable (Fc) as pre-clinical data in various mouse model systems as well as human clinical data have demonstrated that the IgG Fc-domain recapitulates the ability of intact IVIg with respect to its ability to trigger resolution of inflammation. We will further discuss how the findings already have or are in the process of being translated to novel therapeutic approaches to substitute IVIg in treating autoimmune inflammation.

Engineered serum markers for non-invasive monitoring of gene expression in the brain

Measurement of gene expression in the brain requires invasive analysis of brain tissue or non-invasive methods that are limited by low sensitivity. Here we introduce a method for non-invasive, multiplexed, site-specific monitoring of endogenous gene or transgene expression in the brain through engineered reporters called released markers of activity (RMAs). RMAs consist of an easily detectable reporter and a receptor-binding domain that enables transcytosis across the brain endothelium. RMAs are expressed in the brain but exit into the blood, where they can be easily measured. We show that expressing RMAs at a single mouse brain site representing approximately 1% of the brain volume provides up to a 100,000-fold signal increase over the baseline. Expression of RMAs in tens to hundreds of neurons is sufficient for their reliable detection. We demonstrate that chemogenetic activation of cells expressing Fos-responsive RMA increases serum RMA levels >6-fold compared to non-activated controls. RMAs provide a non-invasive method for repeatable, multiplexed monitoring of gene expression in the intact animal brain.

New treatment strategies in Myasthenia gravis

Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disorder characterized by muscle weakness and fatigue. The disease is primarily caused by antibodies targeting acetylcholine receptors (AChR) and muscle-specific kinase (MuSK) proteins at the neuromuscular junction. Traditional treatments for MG, such as acetylcholinesterase inhibitors, corticosteroids, and immunosuppressants, have shown efficacy but are often associated with significant long-term side effects and variable patient response rates. Notably, approximately 15% of patients exhibit inadequate responses to these standard therapies. Recent advancements in molecular therapies, including monoclonal antibodies, B cell-depleting agents, complement inhibitors, Fc receptor antagonists, and chimeric antigen receptor (CAR) T cell-based therapies, have introduced promising alternatives for MG treatment. These novel therapeutic approaches offer potential improvements in targeting specific immune pathways involved in MG pathogenesis. This review highlights the progress and challenges in developing and implementing these molecular therapies. It discusses their mechanisms, efficacy, and the potential for personalized medicine in managing MG. The integration of new molecular therapies into clinical practice could significantly transform the treatment landscape of MG, offering more effective and tailored therapeutic options for patients who do not respond adequately to traditional treatments. These innovations underscore the importance of ongoing research and clinical trials to optimize therapeutic strategies and improve the quality of life for individuals with MG.

Binding to the neonatal Fc receptor enhances the pathogenicity of anti-desmoglein-3 antibodies in keratinocytes

The neonatal Fc receptor (FcRn) is important for numerous cellular processes that involve antibody recycling and trafficking. A major function of FcRn is IgG recycling and half-life prolongation, and FcRn blockade results in a reduction of autoantibodies in IgG-mediated autoimmune diseases. In epithelial cells, FcRn functions in processes different from IgG recycling, such as antibody transcytosis in intestinal cells. In pemphigus vulgaris, an autoimmune disease of the epidermis, IgG autoantibodies directed against desmosomal adhesion proteins, especially desmoglein-3 and -1, cause loss of keratinocyte adhesion. We have previously demonstrated that FcRn blockade with efgartigimod, a human Fc fragment with enhanced FcRn binding, significantly reduces the keratinocyte monolayer fragmentation caused by anti-desmoglein-3 antibodies. This points to a direct function of FcRn in keratinocytes, beyond IgG recycling, but the mechanisms have not yet been elucidated in detail. Here, we show that FcRn binding is required for the full pathogenicity of recombinant anti-desmoglein-3 antibodies in keratinocytes, and that antibodies that exhibit enhanced or reduced FcRn affinity due to targeted substitutions in their Fc region, as well as F(ab')2 fragments not binding to FcRn display different degrees of pathogenicity. Blockade of FcRn by efgartigimod only shows a protective effect on keratinocyte adhesion against antibodies capable of binding to FcRn. Furthermore, antibody-induced degradation of desmoglein-3 in keratinocytes does not depend on FcRn, demonstrating that desmoglein-3 degradation and acantholysis are functionally disconnected processes. Our data suggest that the role of FcRn in autoimmune diseases is likely to be versatile and cell-type dependent, thus stressing the importance of further studies on FcRn function in autoimmune diseases.

Case report: Rapid symptom relief in autoimmune encephalitis with efgartigimod: a three-patient case series

Introduction

Autoimmune encephalitis (AE) comprises a group of inflammatory brain disorders mediated by autoimmune responses. Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis, and anti-γ-aminobutyric acid-B receptor (GABABR) encephalitis are the most prevalent forms, characterized by the presence of antibodies against neuronal cell-surface antigens. Efgartigimod, an antagonist of the neonatal Fc receptor, has proven efficacy in myasthenia gravis treatment. This clinical case report describes the clinical progression and functional outcomes of AE in three patients who received efgartigimod treatment.

Case presentations

Case 1 was a 60-year-old man exhibiting memory impairment and psychiatric disturbances over 11 days. Case 2 was a 38-year-old man with a 1-month history of rapid cognitive decline and seizures. Case 3 was a 68-year-old woman with mental behavioral changes and seizures for 4 months. Anti-GABABR, anti-LGI1, and anti-NMDAR antibodies were confirmed in the respective patients' cerebrospinal fluid or serum. All three patients experienced marked and swift symptomatic relief after four cycles of efgartigimod treatment, with no complication.

Conclusion

Current first-line and second-line treatments for AE have limitations, and efgartigimod has demonstrated potential in the rapid and efficacious treatment of AE, emerging as a promising option for the management of this disease.

Breast milk induced immune haemolytic disease of newborn due to anti-c: A case report

BACKGROUND

Hemolytic disease of fetus and newborn is a major risk factor for anemia and hyperbilirubinemia in newborns. Early identification and diagnosis can significantly improve neonatal health.

CASE REPORT

This report documents a case of hemolytic disease of fetus and newborn presenting as persistent neonatal anemia requiring frequent transfusion support. The underlying cause was determined to be the passive acquisition of hemolytic alloantibodies (anti-c) via breast milk.

CONCLUSION

Importance of antenatal screening for red cell antibodies is gradually being recognized and adopted in developing countries to minimize the burden of HDFN. Breast milk should be considered as a potential source of hemolysing alloantibodies in newborns and may require evaluation in mothers with alloantibodies in her serum.

Population Pharmacokinetics of Casirivimab and Imdevimab in Pediatric and Adult Non-Infected Individuals, Pediatric and Adult Ambulatory or Hospitalized Patients or Household Contacts of Patients Infected with SARS-COV-2

INTRODUCTION

Casirivimab (CAS) and imdevimab (IMD) are two fully human monoclonal antibodies that bind different epitopes on the receptor binding domain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and block host receptor interactions. CAS + IMD and was developed for the treatment and prevention of SARS-CoV-2 infections.

METHODS

A population pharmacokinetic (PopPK) analysis was conducted using pooled data from 7598 individuals from seven clinical studies to simultaneously fit concentration-time data of CAS and IMD and investigate selected covariates as sources of variability in PK parameters. The dataset comprised CAS + IMD-treated pediatric and adult non-infected individuals, ambulatory or hospitalized patients infected with SARS-CoV-2, or household contacts of patients infected with SARS-CoV-2.

RESULTS

CAS and IMD concentration-time data were both appropriately described simultaneously by a two-compartment model with first-order absorption following subcutaneous dose administration and first-order elimination. Clearance estimates of CAS and IMD were 0.193 and 0.236 L/day, respectively. Central volume of distribution estimates were 3.92 and 3.82 L, respectively. Among the covariates identified as significant, body weight and serum albumin had the largest impact (20-34%, and ~ 7-31% change in exposures at extremes, respectively), while all other covariates resulted in small differences in exposures. Application of the PopPK model included simulations to support dose recommendations in pediatrics based on comparable exposures of CAS and IMD between different weight groups in pediatrics and adults following weight-based dosing regimens.

CONCLUSIONS

This analysis provided important insights to characterize CAS and IMD PK simultaneously in a diverse patient population and informed pediatric dose selection.

Antibodies against glutamic acid decarboxylase in intravenous immunoglobulin preparations can affect the diagnosis of type 1 diabetes mellitus

BACKGROUND AND OBJECTIVES

Intravenous immunoglobulins (IVIgs) contain various autoantibodies, including those against glutamic acid decarboxylase (GADAb), a valuable biomarker of type 1 diabetes mellitus. Passive transfer of GADAb from IVIgs to patients poses a risk of misdiagnosis, and information on the specific titres of GADAb and their impact on diagnostic accuracy remains limited. This study aimed to provide further insights into the origin of GADAb detected in patient serum following IVIg infusion.

MATERIALS AND METHODS

GADAb titres in IVIg products from Japan and the United States were measured using enzyme-linked immunosorbent assay-based assays. For reliable quantification, GADAb titres in pooled plasma were quantified and compared with those in the IVIg products. The determined titres were used to estimate the likelihood of passively detecting acquired GADAb in individuals receiving IVIgs.

RESULTS

GADAbs were prevalent in IVIg products; however, the titres varied significantly among different lots and products. Importantly, IVIg-derived GADAb was estimated to remain detectable in patient serum for up to 100 days following a dosage of 2000 mg/kg.

CONCLUSION

Clinicians should consider that IVIg preparations may contain GADAb, which can lead to false-positive results in serological assays. Careful interpretation of the assay results is key to the definitive diagnosis of type 1 diabetes mellitus.

Analysis of Beyfortus® (Nirsevimab) Immunization Campaign: Effectiveness, Biases, and ADE Risks in RSV Prevention

Respiratory infections with respiratory syncytial virus (RSV) account for an important part of hospital admissions for acute respiratory infections. Nirsevimab has been developed to reduce the hospital burden of RSV infections. Compared with the product previously used, it has a stronger binding capacity to RSV F protein and a high affinity for FcRn (neonatal receptor for the Fc fragment of IgG), which extends its lifespan. Nirsevimab has been shown to be highly effective in reducing hospitalization rates of RSV infections but a large or unknown number of treated subjects have been excluded in clinical and post-marketing studies. However, analysis of these studies cannot exclude that, in rare cases, nirsevimab facilitates and worsens RSV infection (or other respiratory infections). This could be attributable to antibody-dependent enhancement (ADE) which has been observed with RSV F protein antibodies in inactivated vaccine trials. This risk has been incompletely assessed in pre-clinical and clinical trials (incomplete exploration of nirsevimab effector functions and pharmacokinetics). ADE by disruption of the immune system (not studied and due to FcRn binding) could explain why there is no reduction in all-cause hospital admissions in treated age groups. Given the high price of nirsevimab, the cost-effectiveness of mass immunization campaigns may therefore be debated from an economic as well as a scientific point of view.

Engineering of pH-dependent antigen binding properties for toxin-targeting IgG1 antibodies using light-chain shuffling

Immunoglobulin G (IgG) antibodies that bind their cognate antigen in a pH-dependent manner (acid-switched antibodies) can release their bound antigen for degradation in the acidic environment of endosomes, while the IgGs are rescued by the neonatal Fc receptor (FcRn). Thus, such IgGs can neutralize multiple antigens over time and therefore be used at lower doses than their non-pH-responsive counterparts. Here, we show that light-chain shuffling combined with phage display technology can be used to discover IgG1 antibodies with increased pH-dependent antigen binding properties, using the snake venom toxins, myotoxin II and α-cobratoxin, as examples. We reveal differences in how the selected IgG1s engage their antigens and human FcRn and show how these differences translate into distinct cellular handling properties related to their pH-dependent antigen binding phenotypes and Fc-engineering for improved FcRn binding. Our study showcases the complexity of engineering pH-dependent antigen binding IgG1s and demonstrates the effects on cellular antibody-antigen recycling.

Patent highlights October-November 2023

A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.

Harnessing the potential of the NALT and BALT as targets for immunomodulation using engineering strategies to enhance mucosal uptake

Mucosal barrier tissues and their mucosal associated lymphoid tissues (MALT) are attractive targets for vaccines and immunotherapies due to their roles in both priming and regulating adaptive immune responses. The upper and lower respiratory mucosae, in particular, possess unique properties: a vast surface area responsible for frontline protection against inhaled pathogens but also simultaneous tight regulation of homeostasis against a continuous backdrop of non-pathogenic antigen exposure. Within the upper and lower respiratory tract, the nasal and bronchial associated lymphoid tissues (NALT and BALT, respectively) are key sites where antigen-specific immune responses are orchestrated against inhaled antigens, serving as critical training grounds for adaptive immunity. Many infectious diseases are transmitted via respiratory mucosal sites, highlighting the need for vaccines that can activate resident frontline immune protection in these tissues to block infection. While traditional parenteral vaccines that are injected tend to elicit weak immunity in mucosal tissues, mucosal vaccines (i.e., that are administered intranasally) are capable of eliciting both systemic and mucosal immunity in tandem by initiating immune responses in the MALT. In contrast, administering antigen to mucosal tissues in the absence of adjuvant or costimulatory signals can instead induce antigen-specific tolerance by exploiting regulatory mechanisms inherent to MALT, holding potential for mucosal immunotherapies to treat autoimmunity. Yet despite being well motivated by mucosal biology, development of both mucosal subunit vaccines and immunotherapies has historically been plagued by poor drug delivery across mucosal barriers, resulting in weak efficacy, short-lived responses, and to-date a lack of clinical translation. Development of engineering strategies that can overcome barriers to mucosal delivery are thus critical for translation of mucosal subunit vaccines and immunotherapies. This review covers engineering strategies to enhance mucosal uptake via active targeting and passive transport mechanisms, with a parallel focus on mechanisms of immune activation and regulation in the respiratory mucosa. By combining engineering strategies for enhanced mucosal delivery with a better understanding of immune mechanisms in the NALT and BALT, we hope to illustrate the potential of these mucosal sites as targets for immunomodulation.

Subcutaneous efgartigimod PH20 in generalized myasthenia gravis: A phase 3 randomized noninferiority study (ADAPT-SC) and interim analyses of a long-term open-label extension study (ADAPT-SC+)

ADAPT-SC (NCT04735432) was designed to evaluate noninferiority of subcutaneous (SC) efgartigimod PH20 to intravenous (IV) efgartigimod in participants with generalized myasthenia gravis (gMG). ADAPT-SC+ (NCT04818671) is an open-label extension study designed to assess long-term safety, tolerability, and efficacy of efgartigimod PH20 SC. Adult participants in ADAPT-SC were randomly assigned to receive a treatment cycle of 4 once-weekly administrations of efgartigimod PH20 SC 1000 ​mg or efgartigimod IV 10 ​mg/kg, followed by 7 weeks of follow-up. Primary endpoint was percentage change from baseline in total immunoglobulin G (IgG) level at week 4 (1 week after the fourth administration). Secondary efficacy endpoints assessed number and percentage of Myasthenia Gravis Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) responders and mean change from baseline in total score for each measure. The primary endpoint was met, demonstrating noninferiority in total IgG reduction between efgartigimod PH20 SC 1000 ​mg and efgartigimod IV 10 ​mg/kg. Clinically meaningful improvements were seen as early as 1 week following the first administration in both treatment arms, with maximal improvements at week 4. Continued treatment cycles of efgartigimod PH20 SC in ADAPT-SC+ have demonstrated long-term safety and consistent improvements in MG-ADL total score. Findings from ADAPT-SC and ADAPT-SC+ demonstrate similar safety and efficacy as observed in the placebo-controlled ADAPT study. Collectively, these findings support noninferiority between efgartigimod PH20 SC 1000 ​mg and efgartigimod IV 10 ​mg/kg, as well as long-term safety, tolerability, and efficacy of efgartigimod PH20 SC for treatment of a broad population of patients with gMG.

In vivo Antibody Painting for Next Generation Weight Loss Drugs

Peptide-based therapeutics are currently in great demand but often suffer from rapid clearance and accumulation in off-target tissues which continue to present barriers in their clinical translation. Here, we developed an electrophilic peptide for the attachment of therapeutics to native immunoglobulin (IgG) in vivo, enabling the bioorthogonal covalent linkage, or 'painting', of peptide drugs of choice to circulating IgGs directly in live animals. Native IgG painting with glucagon-like peptide-1 (GLP-1) results in sustained body weight loss and prolonged blood glucose management after one dose. Such technology might revolutionize the next generation of long-acting peptide-based medicines.

Maternal Immunization with Adjuvanted Recombinant Receptor-Binding Domain Protein Provides Immune Protection against SARS-CoV-2 in Infant Monkeys

Maternal vaccinations administered prior to conception or during pregnancy enhance the immune protection of newborn infants against many pathogens. A feasibility experiment was conducted to determine if monkeys can be used to model the placental transfer of maternal antibody against SARS-CoV-2. Six adult rhesus monkeys were immunized with adjuvanted recombinant-protein antigens comprised of receptor-binding domain human IgG1-Fc fusion proteins (RBD-Fc) containing protein sequences from the ancestral-Wuhan or Gamma variants. The female monkeys mounted robust and sustained anti-SARS-CoV-2 antibody responses. Blood samples collected from their infants after delivery verified prenatal transfer of high levels of spike-specific IgG, which were positively correlated with maternal IgG titers at term. In addition, an in vitro test of ACE2 neutralization indicated that the infants' IgG demonstrated antigen specificity, reflecting prior maternal immunization with either Wuhan or Gamma-variant antigens. All sera showed stronger ACE2-RBD binding inhibition when variants in the assay more closely resembled the vaccine RBD sequence than with more distantly related variants (i.e., Delta and Omicron). Monkeys are a valuable animal model for evaluating new vaccines that can promote maternal and infant health. Further, the findings highlight the enduring nature and safety of the immune protection elicited by an adjuvanted recombinant RBD-Fc vaccine.

Fully human single-domain antibody targeting a highly conserved cryptic epitope on the Nipah virus G protein

Nipah virus infection, one of the top priority diseases recognized by the World Health Organization, underscores the urgent need to develop effective countermeasures against potential epidemics and pandemics. Here, we identify a fully human single-domain antibody that targets a highly conserved cryptic epitope situated at the dimeric interface of the Nipah virus G protein (receptor binding protein, RBP), as elucidated through structures by high-resolution cryo-electron microscopy (cryo-EM). This unique binding mode disrupts the tetramerization of the G protein, consequently obstructing the activation of the F protein and inhibiting viral membrane fusion. Furthermore, our investigations reveal that this compact antibody displays enhanced permeability across the blood-brain barrier (BBB) and demonstrates superior efficacy in eliminating pseudovirus within the brain in a murine model of Nipah virus infection, particularly compared to the well-characterized antibody m102.4 in an IgG1 format. Consequently, this single-domain antibody holds promise as a therapeutic candidate to prevent Nipah virus infections and has potential implications for vaccine development.

Efgartigimod as a promising add-on therapy for myasthenic crisis: a prospective case series

Introduction

Efgartigimod is effective and well-tolerated in patients with anti-acetylcholine receptor (AChR) antibody-positive generalized myasthenia gravis (MG). However, the therapeutic potential and the safety profile of efgartigimod in myasthenic crisis (MC) remained largely unknown.

Methods

This is an observational, prospective, multicenter, real-world study to follow 2 MC patients who initiated efgartigimod as a first-line rescue therapy and 8 cases who used it as an add-on therapy. Baseline demographic features and immunotherapies were collected, and the MG-activities of daily living (MG-ADL) scale was evaluated every week since efgartigimod treatment for 8 weeks. Additionally, serum IgG and anti-AChR antibody levels and the peripheral CD4+ T lymphocytes were measured before and after one cycle of treatment.

Results

Ten patients with MC were enrolled in the study, including 9 anti-AChR antibody positive and 1 anti-muscle-specific kinase (MuSK) positive. All patients were successfully weaned from the ventilation after receiving efgartigimod treatment, with a length of 10.44 ± 4.30 days. After one cycle of infusions, the MG-ADL score reduced from 15.6 ± 4.4 at the baseline to 3.4 ± 2.2, while the corticosteroid dose was tapered from 55.0 ± 20.7 mg to 26.0 ± 14.1 mg. The proportions of regulatory T cells and naïve T cells (% in CD4+ T) significantly decreased post-efgartigimod treatment (5.48 ± 1.23 vs. 6.90 ± 1.80, P=0.0313, and 34.98 ± 6.47 vs. 43.68 ± 6.54, P=0.0313, respectively).

Conclusion

These findings validated the rapid action of efgartigimod in facilitating the weaning process with a good safety profile in patients with MC.

New technologies in therapeutic antibody development: The next frontier for treating infectious diseases

Adaptive immunity to viral infections requires time to neutralize and clear viruses to resolve infection. Fast growing and pathogenic viruses are quickly established, are highly transmissible and cause significant disease burden making it difficult to mount effective responses, thereby prolonging infection. Antibody-based passive immunotherapies can provide initial protection during acute infection, assist in mounting an adaptive immune response, or provide protection for those who are immune suppressed or immune deficient. Historically, plasma-derived antibodies have demonstrated some success in treating diseases caused by viral pathogens; nonetheless, limitations in access to product and antibody titer reduce success of this treatment modality. Monoclonal antibodies (mAbs) have proven an effective alternative, as it is possible to manufacture highly potent and specific mAbs against viral targets on an industrial scale. As a result, innovative technologies to discover, engineer and manufacture specific and potent antibodies have become an essential part of the first line of treatment in pathogenic viral infections. However, a mAb targeting a specific epitope will allow escape variants to outgrow, causing new variant strains to become dominant and resistant to treatment with that mAb. Methods to mitigate escape have included combining mAbs into cocktails, creating bi-specific or antibody drug conjugates but these strategies have also been challenged by the potential development of escape mutations. New technologies in developing antibodies made as recombinant polyclonal drugs can integrate the strength of poly-specific antibody responses to prevent mutational escape, while also incorporating antibody engineering to prevent antibody dependent enhancement and direct adaptive immune responses.

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.

Ion Mobility-Mass Spectrometry and Collision-Induced Unfolding Rapidly Characterize the Structural Polydispersity and Stability of an Fc-Fusion Protein

Fc-fusion proteins are an emerging class of protein therapeutics that combine the properties of biological ligands with the unique properties of the fragment crystallizable (Fc) domain of an immunoglobulin G (IgG). Due to their diverse higher-order structures (HOSs), Fc-fusion proteins remain challenging characterization targets within biopharmaceutical pipelines. While high-resolution biophysical tools are available for HOS characterization, they frequently demand extended time frames and substantial quantities of purified samples, rendering them impractical for swiftly screening candidate molecules. Herein, we describe the development of ion mobility-mass spectrometry (IM-MS) and collision-induced unfolding (CIU) workflows that aim to fill this technology gap, where we focus on probing the HOS of a model Fc-Interleukin-10 (Fc-IL-10) fusion protein engineered using flexible glycine-serine linkers. We evaluate the ability of these techniques to probe the flexibility of Fc-IL-10 in the absence of bulk solvent relative to other proteins of similar size, as well as localize structural changes of low charge state Fc-IL-10 ions to specific Fc and IL-10 unfolding events during CIU. We subsequently apply these tools to probe the local effects of glycine-serine linkers on the HOS and stability of IL-10 homodimer, which is the biologically active form of IL-10. Our data reveals that Fc-IL-10 produces significantly more structural transitions during CIU and broader IM profiles when compared to a wide range of model proteins, indicative of its exceptional structural dynamism. Furthermore, we use a combination of enzymatic approaches to annotate these intricate CIU data and localize specific transitions to the unfolding of domains within Fc-IL-10. Finally, we detect a strong positive, quadratic relationship between average linker mass and fusion protein stability, suggesting a cooperative influence between glycine-serine linkers and overall fusion protein stability. This is the first reported study on the use of IM-MS and CIU to characterize HOS of Fc-fusion proteins, illustrating the practical applicability of this approach.

Beyond nanoparticle-based oral drug delivery: transporter-mediated absorption and disease targeting

Various strategies at the microscale/nanoscale have been developed to improve oral absorption of therapeutics. Among them, gastrointestinal (GI)-transporter/receptor-mediated nanosized drug delivery systems (NDDSs) have drawn attention due to their many benefits, such as improved water solubility, improved chemical/physical stability, improved oral absorption, and improved targetability of their payloads. Their therapeutic potential in disease animal models (e.g., solid tumors, virus-infected lungs, metastasis, diabetes, and so on) has been investigated, and could be expanded to disease targeting after systemic/lymphatic circulation, although the detailed paths and mechanisms of endocytosis, endosomal escape, intracellular trafficking, and exocytosis through the epithelial cell lining in the GI tract are still unclear. Thus, this review summarizes and discusses potential GI transporters/receptors, their absorption and distribution, in vivo studies, and potential sequential targeting (e.g., oral absorption and disease targeting in organs/tissues).

Targeting autoimmune mechanisms by precision medicine in Myasthenia Gravis

Myasthenia Gravis (MG) is a chronic disabling autoimmune disease caused by autoantibodies to the neuromuscular junction (NMJ), characterized clinically by fluctuating weakness and early fatigability of ocular, skeletal and bulbar muscles. Despite being commonly considered a prototypic autoimmune disorder, MG is a complex and heterogeneous condition, presenting with variable clinical phenotypes, likely due to distinct pathophysiological settings related with different immunoreactivities, symptoms' distribution, disease severity, age at onset, thymic histopathology and response to therapies. Current treatment of MG based on international consensus guidelines allows to effectively control symptoms, but most patients do not reach complete stable remission and require life-long immunosuppressive (IS) therapies. Moreover, a proportion of them is refractory to conventional IS treatment, highlighting the need for more specific and tailored strategies. Precision medicine is a new frontier of medicine that promises to greatly increase therapeutic success in several diseases, including autoimmune conditions. In MG, B cell activation, antibody recycling and NMJ damage by the complement system are crucial mechanisms, and their targeting by innovative biological drugs has been proven to be effective and safe in clinical trials. The switch from conventional IS to novel precision medicine approaches based on these drugs could prospectively and significantly improve MG care. In this review, we provide an overview of key immunopathogenetic processes underlying MG, and discuss on emerging biological drugs targeting them. We also discuss on future direction of research to address the need for patients' stratification in endotypes according with genetic and molecular biomarkers for successful clinical decision making within precision medicine workflow.