Immunotherapy in myasthenia gravis in the era of biologics

Early prediction of refractory myasthenia gravis based on response to treatment within the first year of diagnosis

BACKGROUND

The long lead time required to diagnose refractory myasthenia gravis (MG) can prevent early attempts at new treatments. Herein, we aimed to predict refractory MG by comparing treatment responses during the early stages between patients with refractory and non-refractory MG.

METHODS

We retrospectively investigated the medical records of patients with acetylcholine receptor antibody-positive generalized MG. Refractory MG was defined as (1) inability to lower prednisolone below 20 mg/day, (2) requiring regular intravenous immunoglobulin or plasmapheresis, or (3) Myasthenia Gravis Activities of Daily Living score ≥ 6 after treatment with corticosteroids and ≥ 1 oral immunosuppressant for ≥ 12 months.

RESULTS

Of 133 patients, 29 (21.8%) and 104 (78.2%) had refractory and non-refractory MG, respectively. The median duration from the diagnosis of MG to that of refractory MG was 31 months. During the first year following diagnosis, the proportion of patients who achieved a lowest effective prednisolone dose of ≤ 20 mg was lower in the refractory group than in the non-refractory group (69.0% vs. 92.0%). Conversely, the proportions of patients who initiated oral immunosuppressive therapy (58.6% vs. 22.5%), required rescue interventions (48.3% vs. 22.1%), or experienced a myasthenic crisis (34.5% vs. 14.4%) were significantly higher in the refractory group. The risk of refractory MG was 18.7-fold higher in patients who failed to achieve lowest effective prednisolone dose under 20 mg/day and started oral immunosuppressant during the first year than those with neither of these conditions.

CONCLUSIONS

The refractory group displayed distinct clinical features during the early disease stages, including frequent crises and higher levels of immunosuppressive treatment. These features can be used for early prediction of refractory MG.

Rare Diseases, Spotlighting Amyotrophic Lateral Sclerosis, Huntington's Disease, and Myasthenia Gravis: Insights from Landscape Analysis of Current Research

Rare diseases are a diverse group of disorders that, despite each individual condition's rarity, collectively affect a significant portion of the global population. Currently approximately 10,000 rare diseases exist globally, with 80% of these diseases being identified as having genetic origins. In this Review, we examine data from the CAS Content Collection to summarize scientific progress in the area of rare diseases. We examine the publication landscape in the area in an effort to provide insights into current advances and developments. We then discuss the evolution of key concepts in the field, genetic associations, as well as the major technologies and development pipelines of rare disease treatments. We focus our attention on three specific rare diseases: (i) amyotrophic lateral sclerosis, a terminal neurodegenerative disease affecting the central nervous system resulting in progressive loss of motor neurons that control voluntary muscles; (ii) Huntington's disease, another terminal neurodegenerative disease that causes progressive degeneration of nerve cells in the brain, with a wide impact on a person's functional abilities; and (iii) myasthenia gravis, a chronic autoimmune synaptopathy leading to skeletal muscle weakness. While the pathogenesis of these rare diseases is being elucidated, there is neither a cure nor preventative treatment available, only symptomatic treatment. The objective of the paper is to provide a broad overview of the evolving landscape of current knowledge on rare diseases and specifically on the biology and genetics of the three spotlighted diseases, to outline challenges and evaluate growth opportunities, an aim to further efforts in solving the remaining challenges.

Rozanolixizumab for Myasthenia Gravis: a breakthrough treatment and future prospects

Myasthenia gravis is a rare chronic autoimmune disorder affecting the post-synaptic neuromuscular junction, primarily mediated by pathogenic immunoglobulin G (IgG) targeting specific proteins like acetylcholine receptor (AChR), muscle-specific tyrosine kinase (MuSK), and low-density lipoprotein receptor-related protein 4 (LRP4). Modulating pathogenic IgG is a promising approach for disease management. Rozanolixizumab, a human IgG4 neonatal Fc receptor (FcRn) inhibitor, enhances the degradation of pathogenic IgG by 78%, marking a significant advancement in treating generalized myasthenia gravis. It offers effective management for patients with AChR or MuSK antibodies and is administered subcutaneously with mild to moderate adverse events. However, the safety and efficacy of rozanolixizumab require further validation through real-world post-marketing studies. If current trial results are confirmed, rozanolixizumab may become a preferred treatment option for myasthenia gravis in the near future. This review examines clinical trials evaluating the pharmacokinetics, efficacy, and safety of rozanolixizumab in patients with generalized myasthenia gravis and discusses ongoing trials and future research directions.

Efficacy and safety of different dosages of rituximab for myasthenia gravis: a single-arm meta-analysis

BACKGROUND

Rituximab (RTX) is one of the treatment options for refractory myasthenia gravis (MG), yet the optimal dosing schedule remains undetermined. Our study aims to explore this issue and offer a valuable reference for clinical dosing.

METHODS

This is a single-arm meta-analysis. Studies in adults with myasthenia gravis published before 31 December 2023 were searched in PubMed, Web of Science, and other databases. Two primary effectiveness outcomes were analyzed: (1) Proportion of patients achieving minimal manifestation status (MMS) or better, (2) Change in Quantitative MG Score (QMGs) after RTX treatment. Safety outcomes included the incidence and description of serious adverse events (SAEs) and adverse events (AEs). Forest plots were generated to provide an overview and detailed combined effects. Publication bias was evaluated using funnel plots and the Egger test. Conventional dose refers to an RTX regimen similar to that used for the treatment of B-cell lymphoma: 375 mg/m2 per week for 4 weeks or 1000 mg for Weeks 1 and 3. Dosing regimens below the conventional dose in a treatment cycle are defined as low dose.

RESULTS

A total of 1037 MG patients received RTX treatment. Overall, 59.0% (95% CI: 48.2-69.8%, n = 599) of patients achieved MMS or better, with a mean decrease in QMGs of 6.81 (95% CI, -9.27 to -4.35, n = 222). The low-dose group showed a higher proportion of patients achieving MMS or better (76.6% vs 51.6%) and a more significant decrease in QMGs from baseline (-9.04 vs -3.62) compared to the conventional dose group (P < 0.01). Differences in the incidence of SAEs and AEs between the two groups were not significant (P > 0.05). Univariate meta-regression analyses showed that the dose administered was significantly associated with the proportion of MMS or better and the change in QMGs, whereas the proportion of Musk patients was not significantly associated with any of the outcomes. Stepwise logistic regression analyses showed that non-refractory MG, mild disease severity (MGFA classification), and low-dose were significant predictors for achieving an MMS or better prognosis, whereas for achieving improvement or better, only low dose was an independent predictor.

CONCLUSION

RTX can improve clinical symptoms, reduce QMGs in MG patients and the use of oral glucocorticoids and other immunosuppressants. The efficacy of low-dose RTX in treating MG patients is more effective than conventional-dose RTX and demonstrates a better safety profile. Mild disease severity, non-refractory MG, low dose, and MuSK-MG over AChR-MG predict better efficacy. Large randomized controlled trials are necessary to evaluate the efficacy and safety of RTX in MG patients and its various subtypes.

Predictors of achieving minimal manifestations or better status in ocular myasthenia gravis with immunotherapy

BACKGROUND

Ocular myasthenia gravis (MG), while less severe than generalized MG, significantly impairs quality of life due to its impact on vision and daily activities. Immunotherapy is a key treatment, yet the optimal timing for initiation remains undefined.

OBJECTIVE

To identify predictive factors for achieving minimal manifestations (MM) or better status in ocular MG patients receiving immunotherapy, with a focus on the role of early intervention.

METHODS

We conducted a retrospective analysis of 48 ocular MG patients treated at our institution. Patients were categorized based on whether they achieved MM or better status. Clinical variables were analyzed using univariate, receiver-operating characteristic, and multivariate logistic regression analyses.

RESULTS

MM or better status was achieved in 34/48 patients (median onset age: 55 years). Time from symptom onset to immunotherapy initiation was significantly shorter in those who achieved MM or better status (median: 30 days vs. 1095 days; p < 0.001). Receiver-operating characteristic analysis determined a 255-day cutoff for immunotherapy initiation, yielding sensitivity of 92.9% and specificity of 91.2% (AUC = 0.986, 95% CI: 0.962-1.000, p < 0.001). Logistic regression confirmed early immunotherapy as an independent predictor.

CONCLUSIONS

Early initiation of immunotherapy (< 255 days from onset) significantly improves the likelihood of achieving MM or better status in ocular MG. These findings support the need for prompt diagnosis and treatment to optimize outcomes.

The JAK1/3 Inhibitor Tofacitinib Regulates Th Cell Profiles and Humoral Immune Responses in Myasthenia Gravis

INTRODUCTION/AIMS

Tofacitinib, a first-generation Janus kinase (JAK) 1/3 inhibitor, is commonly used for treating ulcerative colitis and rheumatoid arthritis. However, its role in myasthenia gravis (MG) remains unclear. This study aimed to evaluate the immunomodulatory effects of tofacitinib on experimental autoimmune myasthenia gravis (EAMG) and peripheral blood mononuclear cells (PBMCs) from patients with MG.

METHODS

Flow cytometry, enzyme-linked immunosorbent assay (ELISA), quantitative reverse transcription polymerase chain reaction (qRT-PCR), and Western blot were used to evaluate the effects of tofacitinib on T helper (Th) cell profiles, humoral immune responses, and the JAK-signal transducer and activator of transcription (STAT) pathway proteins.

RESULTS

In vivo, tofacitinib significantly ameliorated EAMG severity in rats, reducing the proportions of Th1, Th17 and memory B cells, and anti-acetylcholine receptor (AChR) antibodies levels, while increasing the proportions of regulatory T (Treg) cells. In vitro, tofacitinib administration resulted in a significant decrease in the proportions of Th1 and IgG-secreting B cell, and a significant upregulation of Treg cells in mononuclear cells (MNCs) from EAMG rats, which was consistent with findings in PBMCs from MG patients. Further analysis revealed that tofacitinib inhibited CD4+ T cell differentiation into Th1 by decreasing phosphorylated STAT1 levels, while promoting Treg differentiation via increased phosphorylated STAT5 levels in MNCs from EAMG rats.

DISCUSSION

Tofacitinib modulates Th cell profiles and humoral immune responses by targeting the JAK-STAT pathway, suggesting its potential as a therapeutic candidate for MG. Further clinical studies are warranted to evaluate the efficacy and safety of tofacitinib in MG patients.

Myasthenia gravis in 2025: five new things and four hopes for the future

The last 10 years has brought transformative developments in the effective treatment of myasthenia gravis (MG). Beginning with the randomized trial of thymectomy in myasthenia gravis that demonstrated efficacy of thymectomy in nonthymomatous MG, several new treatment approaches have completed successful clinical trials and regulatory launch. These modalities, including B cell depletion, complement inhibition, and blockade of the neonatal Fc receptor, are now in use, offering prospects of sustained remission and neuromuscular protection in what is a long-term disease. In this review, we update our clinico-immunological review of 2016 with these important advances, examine their role in treatment algorithms, and focus attention on key issues of biomarkers for prognostication and the growing cohort of older patients, both those with long-term disease, and late-onset MG ('LOMG'). We close by expressing our four hopes for the next 5-10 years: improvements in laboratory medicine to facilitate rapid diagnosis, effective strategies for neuromuscular protection, more research into and better understanding of pathophysiology and treatment response in older individuals, and the potentially transformative role of therapies aimed at delivering a durable response such as chimeric antigen receptor (CAR) T cells. Our postscript summarizes some emerging themes in the field of serological and online biomarkers, which may develop greater stature in the next epoch.

Successful sequential therapy with rituximab and telitacicept in refractory Anti-NMDA receptor encephalitis and MOG-associated demyelination: a case report and literature review

Clinical management of the rare and complex overlapping syndrome of MOG-antibody disease and anti-NMDAR encephalitis (MNOS), which has an uncertain pathogenesis and a high risk of recurrence, is highly challenging. We describe the case of a 19 years-old female patient, who first complained of headache, fever, and irritability. After that, she experienced frequent seizures and mood disorders. The diagnosis of MNOS was verified through antibody tests and imaging. For the patient, intravenous immunoglobulin and high-dose methylprednisolone were effective as first-line immunotherapy. Long-term immunotherapy with oral prednisone and mycophenolate mofetil was used to prevent relapses. However, over six years, the patient had five relapses when the mycophenolate mofetil dosage was reduced. The patient's condition stabilized after taking rituximab as second-line immunotherapy, with less than 1% of total lymphocytes being CD19+ cells. Eleven months later, the plasmablast ratio increased, and patients experienced new symptoms such as bilateral optic neuritis. After that, the patient got telitacicept injections regularly for 13 months, during which time her symptoms subsided, and there were no adverse effects or relapses. This case suggests that telitacicept may be a viable adjunct or sequential therapy option for the depletion of B cells in MNOS.

Safety and efficacy of satralizumab in patients with generalised myasthenia gravis (LUMINESCE): a randomised, double-blind, multicentre, placebo-controlled phase 3 trial

BACKGROUND

Evidence from preclinical studies suggests that IL-6 signalling has the potential to modulate immunopathogenic mechanisms upstream of autoantibody effector mechanisms in patients with generalised myasthenia gravis. We aimed to assess the safety and efficacy of satralizumab, a humanised monoclonal antibody targeting the IL-6 receptor, in patients with generalised myasthenia gravis.

METHODS

LUMINESCE was a randomised, double-blind, placebo-controlled, multicentre, phase 3 study at 105 sites, including hospitals and clinics, globally. Eligible patients were aged 12 years and older, with seropositive generalised myasthenia gravis (autoantibodies to the acetylcholine receptor [AChR-IgG], muscle-specific kinase [MuSK-IgG], or low-density lipoprotein receptor-related protein 4 [LRP4-IgG]), a Myasthenia Gravis Foundation of America severity class II-IV, a Myasthenia Gravis Activities of Daily Living (MG-ADL) score of 5 or more (non-ocular contribution >50%), and use of stable background therapy. Patients were randomly assigned (1:1) with a permuted-block randomisation method to receive subcutaneous satralizumab (120 mg for bodyweight ≤100 kg; 180 mg for bodyweight >100 kg) or placebo at weeks 0, 2, 4, and every 4 weeks thereafter until week 24. Randomisation was stratified according to background therapy, autoantibody type, and geographical region. The primary efficacy endpoint was mean change from baseline in total MG-ADL score at week 24 in the modified intention-to-treat population (all randomised AChR-IgG-positive patients who completed at least one post-baseline MG-ADL assessment). Safety was assessed in all randomly assigned patients who received at least one dose of study drug. The open-label extension was terminated early because of the sponsor's decision to halt further development of satralizumab for treatment of generalised myasthenia gravis. This trial is registered with ClinicalTrials.gov, NCT04963270, and EudraCT, 2020-004436-21.

FINDINGS

Between Oct 19, 2021, and Aug 15, 2023, 188 patients were randomly assigned to satralizumab (n=96) or placebo (n=92). 166 AChR-IgG-positive patients (80 in the placebo group and 86 in the satralizumab group) were included in the modified intention-to-treat population. At week 24, statistically significant yet small improvements in MG-ADL score were observed with satralizumab versus placebo (adjusted mean -3·59, 95% CI -4·15 to -3·02 vs -2·57, -3·25 to -1·88; difference -1·02, -1·88 to -0·16; p=0·0120). The proportion of patients with at least one adverse event during the double-blind period was slightly higher in patients treated with satralizumab compared with patients treated with placebo (86 [90%] patients vs 67 [73%] patients). Three serious adverse events (in three [3%] patients) were reported in the satralizumab group (pneumonia, pyelonephritis, and increased lipase) compared with nine (in six [7%] patients) serious adverse events in the placebo group (COVID-19, COVID-19 pneumonia, bacterial urinary tract infection, chest pain, back pain, and rosacea). There were no deaths or adverse events of special interest.

INTERPRETATION

Satralizumab was well tolerated and resulted in small improvements in patient-reported and clinician-reported outcomes compared with placebo at week 24 in patients with AChR-IgG-positive generalised myasthenia gravis. Further research analysing the immunological underpinnings of the observed clinical response to IL-6 signalling inhibition in patients with generalised myasthenia gravis and exploring the role of IL-6 in autoantibody-mediated diseases is warranted.

FUNDING

F Hoffmann La Roche.

Targeting NF-kappaB-inducing kinase shapes B-cell homeostasis in myasthenia gravis

BACKGROUND

B cell immune dysregulation plays a critical role in myasthenia gravis (MG). However, targeted B-cell therapy such as rituximab may result in long-term peripheral B cell clearance and allow for the survival of plasma cells, contributing to frequent infections and relapses. Therefore, we aimed to identify potential novel therapeutic targets that preserve part of B cell function while inhibiting antibody-secreting cells (ASCs).

METHODS

The transcriptome of sorted CD19+B cells obtained from MG patients in active and remission state was performed by RNA sequencing. The hallmark gene NF-kappaB-inducing kinase (NIK/MAP3K14) associated with NF-κB and TNF signaling was identified, and the expression levels of NIK in CD19+B cells, CD4+T cells and serum from new-onset MG patients and controls were validated by flow cytometry, qPCR and ELISA. In vitro and in vivo, the effects of NIK inhibitor (B022) on the function of CD19+B cells and CD4+T cells were detected under the MG PBMCs, sorted B cells and experimental autoimmune MG (EAMG) rat model, respectively.

RESULTS

The expression levels of NIK were upregulated in CD19+B cells, CD4+T cells and serum from new-onset MG patients. Notably, increased serum NIK levels were positively correlated with disease severity and decreased with disease remission. NIK inhibitor B022 significantly reduced B-cell activation, proliferation, ASCs differentiation and pathogenic function, as well as CD4+T cell activation and Th17 cells differentiation in vitro. Intraperitoneal injection of B022 ameliorated the severity of EAMG rats, and reduced proportion of pathogenic B and T cell subsets, antibody levels and postsynaptic membrane damage.

CONCLUSIONS

Targeting NIK with small molecule kinase inhibitors can effectively shape B cell homeostasis, and exhibit protective effects in the EAMG rat model, which may be an effective novel treatment strategy for MG.

Advances in the genetics of myasthenia gravis: insights from cutting-edge neuroscience research

Myasthenia gravis (MG) is an autoimmune disorder involving complex interactions between genetic and environmental factors. Genome-wide association studies (GWAS), transcriptome-wide association studies (TWAS), and other methods have identified multiple novel susceptibility loci and genes, providing crucial insights into the genetic etiology of MG. Moreover, the pivotal roles of epigenetic mechanisms, such as DNA methylation, histone modifications, and non-coding RNAs, in the pathogenesis of MG are gradually being unveiled. This review comprehensively summarizes the latest advances in MG genetic research, focusing on the discovery and validation of susceptibility genes, genetic heterogeneity and subtype-specific genetic factors, gene-environment interactions, epigenetic mechanisms, and progress in genetics-based diagnostic and prognostic biomarkers.

Persistent symptoms, exacerbations and drug side effects despite treatment in myasthenia gravis

BACKGROUND

Generalized myasthenia gravis (gMG) is characterized by fluctuating muscle weakness. Exacerbation frequency, adverse events (AEs) related to immunosuppressant therapy and healthcare resource utilization (HCRU) are not well understood. Our study aimed to describe long-term clinical outcomes, drug-related AEs and estimated HCRU in gMG patients.

METHODS

This was a retrospective cohort analysis of clinical data from patients with gMG followed-up over eight consecutive years in a Spanish referral unit. Myasthenia Gravis Foundation of America (MGFA) clinical classification, MGFA post-interventional status (MGFA-PIS), Myasthenia Gravis Activities of Daily Living (MG-ADL) score, exacerbations, MG crises, therapies, AEs reported, specialist consultations and emergency room visits were studied biannually. An estimation of HRCU was made based on these data.

RESULTS

Some 220 patients newly diagnosed with gMG were included. Ninety percent were seropositive (84.5% anti-acetylcholine receptor [AChR], 5.9% anti-muscle-specific kinase [MuSK]). Baseline mean MG-ADL score was 5.04 points (SD 3.17), improving to 0.7 points (SD 1.40) after 8 years. Exacerbations were more frequent in years 1-2 (30.1%) but still occurred in years 7-8 (20.2%). Myasthenic crisis frequency remained 1% in years 7-8. Eighty-nine percent achieved MGFA-PIS minimal manifestations or better at 8 years. Fifty-one percent of patients reported at least one AE during the study period, leading to drug withdrawal in approximately 20% of cases. HCRU decreased between years 1-2 to years 7-8 with an estimated cost of MG from 8074.19 € per patient/year to 1679.46 €, respectively.

CONCLUSIONS

There is a group of MG patients that suffers from persistent symptoms and exacerbations (11%-20%) or MG crises, and drug AEs, which may increase disease burden and impact on the healthcare system.

Dysregulated Long Non-coding RNAs in Myasthenia Gravis- A Mini-Review

Myasthenia gravis (MG) is an acquired autoimmune disease that is mediated by humoral immunity, supplemented by cellular immunity, along with participation of the complement system. The pathogenesis of MG is complex; although autoimmune dysfunction is clearly implicated, the specific mechanism remains unclear. Long non-coding RNAs (lncRNAs) are a class of non-coding RNA molecules with lengths greater than 200 nucleotides, with increasing evidence of their rich biological functions and high-level structure conservation. LncRNAs can directly interact with proteins and microRNAs to regulate the expression of target genes at the transcription and post-transcription levels. In recent years, emerging studies have suggested that lncRNAs play roles in the differentiation of immune cells, secretion of immune factors, and complement production in the human body. This suggests the involvement of lncRNAs in the occurrence and progression of MG through various mechanisms. In addition, the differentially expressed lncRNAs in peripheral biofluid may be used as a biomarker to diagnose MG and evaluate its prognosis. Moreover, with the development of lncRNA expression regulation technology, it is possible to regulate the differentiation of immune cells and influence the immune response by regulating the expression of lncRNAs, which will provide a potential therapeutic option for MG. Here, we review the research progress on the role of lncRNAs in different pathophysiological events contributing to MG, focusing on specific lncRNAs that may largely contribute to the pathophysiology of MG, which could be used as potential diagnostic biomarkers and therapeutic targets.

Ravulizumab and Efgartigimod in Myasthenia Gravis: A Real-World Study

BACKGROUND AND OBJECTIVES

Biologics that target pathogenic antibodies (Abs) and their effector functions such as the complement inhibitor ravulizumab and the neonatal Fc receptor agonist efgartigimod have recently been approved for the treatment of acetylcholine receptor (AChR)-Ab-positive myasthenia gravis (MG), but comparative studies are lacking.

METHODS

In a prospective, exploratory real-world study, we assessed clinical efficacy, safety, and biological effects of ravulizumab and efgartigimod treatment initiation. Myasthenia Gravis-Activities of Daily Living and Quantitative Myasthenia Gravis scores were used as clinical endpoints. Ab effector functions were determined by AChR-Ab-dependent complement activation and phagocytosis assays and systemic complement activation profiling.

RESULTS

We observed similar moderate short-term efficacy of ravulizumab and efgartigimod in achieving clinical improvement. Ravulizumab reduced systemic terminal complement activation, but neither treatment showed significant effects on complement pathways proximal to C5 or functional capacities of AChR-Abs. Both treatment modalities were well tolerated with no serious adverse events reported.

DISCUSSION

Clinical benefits obtained with ravulizumab and efgartigimod can be remarkably heterogeneous in daily clinical practice. Neither treatment relevantly changed effector functions of pathogenic AChR-Abs, supporting the concept that durable disease control in MG requires continuous administration of both fast-acting agents.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that in AChR-Ab-positive patients with generalized MG, ravulizumab and efgartigimod provide comparable modest improvement in MG functional scales.

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.

Myasthenia gravis complicated with pulmonary infection by Nocardia cyriacigeorgica: a case report and literature review

Myasthenia gravis (MG) is an autoimmune disease. Patients with MG due to compromised autoimmune regulation, progressive muscle weakness, and prolonged use of immunosuppressants and glucocorticoid, often present with concomitant infections. However, cases of MG complicated by Nocardia infection are rare. In this case, we report MG complicated with pulmonary infection by Nocardia cyriacigeorgica. A 71-year-old male farmer who was admitted for management of MG. After 7 weeks of treatment of MG, the patient reported improvement. However, clinical presentation, inflammatory markers, and imaging findings supported a diagnosis of pulmonary infection. To further elucidate the etiology, Nocardia was identified in sputum smear microscopy and sputum culture, with 16S rRNA gene sequencing confirming N. cyriacigeorgica. The patient was prescribed trimethoprim-sulfamethoxazole. After 1 month of treatment, clinical symptoms of MG and pulmonary nocardiosis showed significant improvement. Additionally, we searched PubMed for case reports of Nocardia cyriacigeorgica pulmonary infection from 2010 to 2024 and conducted a statistical analysis of the case information. This report aims to highlights the increased risk of pulmonary Nocardia infection in MG patients after the use of steroids and immunosuppressants, thereby enhancing clinical awareness.

Diagnostic value of antibody concentration ratio for treatment-refractory myasthenia gravis

OBJECTIVE

This study aimed to assess the diagnostic potential of the Antibody concentration ratio in identifying treatment-refractory myasthenia gravis (MG).

METHODS

A retrospective analysis was conducted on 116 MG patients who underwent antibody detection at least twice between June 1, 2015, and June 1, 2023. Demographic and clinical characteristics were collated to ascertain their association with refractory MG. The Antibody Concentration Ratio was applied to determine treatment response, using the International Consensus Guidance criteria as the reference standard. The area under nonparametric receiver operating characteristic curve (AUC), sensitivity, specificity, and accuracy were calculated to assess the diagnostic efficacy of the Antibody concentration ratio following consecutive immunotherapy relative to initial antibody concentrations for refractory MG.

RESULTS

19 out of 116 patients were unequivocally diagnosed with refractory MG. A significant correlation was found between the Antibody Concentration Ratio and refractory MG status in treatment-refractory and treatment-responsive patients. Subsequently, the AUC demonstrated the robust diagnostic capability of the Antibody concentration ratio for refractory MG, with an AUC of 0.8709 (95% CI: 0.7995-0.9422, p < 0.0001). The optimal cut-off value stood at 0.8903, exhibiting a sensitivity of 94.74% (95% CI: 75.36%-99.73%), a specificity of 68.04% (95% CI: 58.23%-76.48%), and accuracy of 72.41% (95% CI: 64.28%-80.54%).

CONCLUSION

Elevated Antibody Concentration Ratio is intrinsically linked with refractory MG and exhibits potential as an diagnostic biomarker for the condition.

Association Between the Immune Checkpoint Inhibitor Durvalumab and Myasthenia Gravis: A Comprehensive Review

Immune checkpoint inhibitors (ICIs), including Imfinzi (durvalumab), have revolutionized cancer treatment by stimulating the body's immune system to target cancerous cells. Although pharmaceuticals offer therapeutic benefits, several drugs have been associated with immune-related adverse events (irAEs), including the uncommon but serious condition known as myasthenia gravis (MG). This review synthesizes data from pertinent research to offer a thorough evaluation of the literature on the underlying mechanisms, clinical manifestations, and therapeutic approaches for durvalumab-induced MG. The incidence of MG in patients on durvalumab and other ICIs is typically low, with less than 1% documented, despite the potential for severe problems associated with the disease. Durvalumab disrupts immunological tolerance by stimulating autoreactive T-cells and inducing the production of autoantibodies. The clinical consequences of MG need meticulous monitoring, prompt identification, and suitable management to efficiently control the condition. Medical practitioners must carefully weigh the positive effects of ICIs against the possible hazards, emphasizing the necessity for more extensive investigation to improve patient results and establish uniform treatment protocols.

Dihydroartemisinin ameliorates experimental autoimmune myasthenia gravis by regulating CD4+ T cells and modulating gut microbiota

BACKGROUND

Dihydroartemisinin (DHA), a derivative and active metabolite of artemisinin, possesses various immunomodulatory properties. However, its role in myasthenia gravis (MG) has not been clearly explored. Here, we investigated the role of DHA in experimental autoimmune myasthenia gravis (EAMG) and its potential mechanisms.

METHODS

The AChR97-116 peptide-induced EAMG model was established in Lewis rats and treated with DHA. Flow cytometry was used to assess the release of Th cell subsets and Treg cells, and 16S rRNA gene amplicon sequence analysis was applied to explore the relationship between the changes in the intestinal flora after DHA treatment. In addition, network pharmacology and molecular docking were utilized to explore the potential mechanism of DHA against EAMG, which was further validated in the rat model by immunohistochemical and RT-qPCR for further validation.

RESULTS

In this study, we demonstrate that oral administration of DHA ameliorated clinical symptoms in rat models of EAMG, decreased the expression level of Th1 and Th17 cells, and increased the expression level of Treg cells. In addition, 16S rRNA gene amplicon sequence analysis showed that DHA restored gut microbiota dysbiosis in EAMG rats by decreasing Ruminococcus abundance and increasing the abundance of Clostridium, Bifidobacterium, and Allobaculum. Using network pharmacology, 103 potential targets of DHA related to MG were identified, and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that PI3K-AKT signaling pathway was related to the treatment of DHA on EAMG. Meanwhile, molecular docking verified that DHA has good binding affinity to AKT1, CASP3, EGFR, and IGF1. Immunohistochemical staining showed that DHA treatment significantly inhibited the phosphorylated expression of AKT and PI3K in the spleen tissues of EAMG rats. In EAMG rats, RT-qPCR results also showed that DHA reduced the mRNA expression levels of PI3K and AKT1.

CONCLUSIONS

DHA ameliorated EAMG by inhibiting the PI3K-AKT signaling pathway, regulating CD4+ T cells and modulating gut microbiota, providing a novel therapeutic approach for the treatment of MG.

Interactions Between Extracellular Vesicles and Autophagy in Neuroimmune Disorders

Neuroimmune disorders, such as multiple sclerosis, neuromyelitis optica spectrum disorder, myasthenia gravis, and Guillain-Barré syndrome, are characterized by the dysfunction of both the immune system and the nervous system. Increasing evidence suggests that extracellular vesicles and autophagy are closely associated with the pathogenesis of these disorders. In this review, we summarize the current understanding of the interactions between extracellular vesicles and autophagy in neuroimmune disorders and discuss their potential diagnostic and therapeutic applications. Here we highlight the need for further research to fully understand the mechanisms underlying these disorders, and to develop new diagnostic and therapeutic strategies.

Case report: Rapid clinical improvement in acute exacerbation of MuSK-MG with efgartigimod

Myasthenia gravis with positive MuSK antibody often involves the bulbar muscles and is usually refractory to acetylcholinesterase inhibitors. For MuSK-MG patients who experience acute exacerbations and do not respond to conventional treatments, there is an urgent need to find more suitable treatment options. With the advent of biologic agents, efgartigimod has shown promising results in the treatment of MG. We report a 65-year-old MuSK-MG patient who presented with impaired eye movements initially, and the symptoms rapidly worsened within a week, affecting the limbs and neck muscles, and had difficulties in chewing and swallowing. Lymphoplasmapheresis did not achieve satisfactory results, but after a cycle of efgartigimod treatment, the patient's symptoms gradually improved and remained in a good clinical state for several months.

Vitamin D add on the standard treatment for myasthenia gravis symptoms following total gastrectomy: a case report

BACKGROUND

Myasthenia gravis (MG) is a long-term autoimmune disorder that affects the neuromuscular junction, causing muscle weakness and fatigue as its primary clinical features. Vitamin D is crucial for both the autoimmune response and skeletal muscle function.

CASE PRESENTATION

Here, we presented a case report documenting the substantial improvement in symptoms experienced by a patient who underwent subtotal gastrectomy for gastric cancer following high-dose Vitamin D supplementation. The patient developed generalized MG two months after the surgery and did not respond adequately to pyridostigmine therapy, experiencing a progressive deterioration of the condition. A significant reduction in vitamin D concentration was observed following subtotal gastrectomy. In response, high-dose vitamin D supplementation was administered to the patient. Within one week of treatment, swallowing symptoms improved, enabling the consumption of a small amount of liquid food. By the second week, substantial swallowing and neck function improvements were evident. After one month, the patient regained the ability to straighten the neck while walking and consumed a regular diet despite persistent difficulties chewing hard food.

CONCLUSIONS

This case underscores the therapeutic potential of vitamin D in alleviating MG symptoms, particularly in individuals with compromised vitamin D levels following gastrectomy. The observed improvements present a new perspective on the possible involvement of vitamin D supplementation in the management of postoperative MG cases.

Effectiveness and safety of telitacicept for refractory generalized myasthenia gravis: a retrospective study

Background

Refractory generalized myasthenia gravis (GMG) remains a substantial therapeutic challenge. Telitacicept, a recombinant human B-lymphocyte stimulator receptor-antibody fusion protein, holds promise for interrupting the immunopathology of this condition.

Objectives

This study retrospectively assessed the effectiveness and safety of telitacicept in patients with refractory GMG.

Design

A single-center retrospective study.

Methods

Patients with refractory GMG receiving telitacicept (160 mg/week or biweekly) from January to September in 2023 were included. We assessed effectiveness using Myasthenia Gravis Foundation of America post-intervention status (MGFA-PIS), myasthenia gravis treatment status and intensity (MGSTI), quantitative myasthenia gravis (QMG), and MG-activity of daily living (ADL) scores, alongside reductions in prednisone dosage at 3- and 6-month intervals. Safety profiles were also evaluated.

Results

Sixteen patients with MGFA class II-V refractory GMG were included, with eight females and eight males. All patients were followed up for at least 3 months, and 11 patients reached 6 months follow-up. At the 3-month evaluation, 75% (12/16) demonstrated clinical improvement with MGFA-PIS. One patient achieved pharmacological remission, two attained minimal manifestation status, and nine showed functional improvement; three remained unchanged, and one deteriorated. By the 6-month visit, 90.1% (10/11) sustained significant symptomatic improvement. MGSTI scores and prednisone dosages significantly reduced at both follow-ups (p < 0.05). MG-ADL and QMG scores showed marked improvement at 6 months (p < 0.05). The treatment was well tolerated, with no severe adverse events such as allergy or infection reported.

Conclusion

Our exploratory investigation suggests that telitacicept is a feasible and well-tolerated add-on therapy for refractory GMG, offering valuable clinical evidence for this novel treatment option.

Case report: A highly active refractory myasthenia gravis with treatment of telitacicept combined with efgartigimod

There is always a lack of effective treatment for highly active refractory generalized myasthenia gravis (GMG). Recently, telitacicept combined with efgartigimod significantly reduces circulating B cells, plasma cells, and immunoglobulin G, which brings promising therapeutic strategies. We report a case of a 37-year-old female patient with refractory GMG, whose condition got significant improvement and control with this latest treatment after multiple unsuccessful therapies of immunosuppressants. The new combination deserves further attention in the therapeutic application of myasthenia gravis.

The analysis of factors affecting medication adherence in patients with myasthenia gravis: a cross-sectional study

Background

Clinically, patients with myasthenia gravis are generally treated with drugs to improve their physical condition, and poor medication adherence can hinder their recovery. Many studies have shown the importance of medication adherence for effective treatment. Various factors may affect a patient's medication adherence; however, studies concerning medication adherence in patients with myasthenia gravis are rare.

Objectives

This study aimed to identify the factors related to medication adherence in patients with myasthenia gravis, and determine the possibility of predicting medication adherence.

Methods

This cross-sectional observational study was conducted among inpatients and outpatients with myasthenia gravis of the First Affiliated Hospital of Guangzhou University of Chinese Medicine in China. Data on patient demographics, disease-related characteristics, and medical treatment were collected. We evaluated medication adherence of the patients using the Morisky Medication Adherence Scale-8, Beliefs about Medicines Questionnaire, and the Self-efficacy for Appropriate Medication Use Scale.

Results

We distributed 200 questionnaires and finally retrieved 198 valid questionnaires. A total of 139 (70.2%) women participated in this study, and 81 (40.9%) among the 198 participants were aged 40-59 years. In total, 103 (52.0%) participants exhibited bad adherence to pharmacological treatment, and factors such as taking medication irregularly [odds ratio (OR) = 0.242, 95% CI = 0.093-0.627], the necessity of taking medicine (OR = 1.286, 95% CI = 1.142-1.449), the concerns of taking medicine (OR = 0.890, 95% CI = 0.801-0.988), and the self-efficacy for taking medications under difficult circumstances (OR = 1.194, 95% CI = 1.026-1.389) had statistically significant impacts on medication adherence.

Conclusion

Our study shows that taking medication irregularly and concerns of taking medicine are the risk factors for medication adherence. Meanwhile, the necessity of talking medicine and self-efficacy for taking medications under difficult circumstances are the protective factors for medication adherence. Our findings can help medical staff to enhance patients' medication adherence by informing patients necessary medical knowledge, emphasizing the necessity for medication, relieving patients' concerns regarding medication, and improving the self-efficacy for taking medications under difficult circumstances.

Batoclimab vs Placebo for Generalized Myasthenia Gravis: A Randomized Clinical Trial

Importance

Myasthenia gravis (MG) is caused by autoantibodies that disrupt the neuromuscular junction. The neonatal fragment crystallizable receptor (FcRn) antagonists, efgartigimod and rozanolixizumab, reduce immunoglobulin G (IgG) level in the circulation and alleviate symptoms in patients with generalized MG.

Objective

To examine the efficacy and safety profile of batoclimab, a monoclonal IgG1 antibody, in patients with generalized MG.

Design, Setting, and Participants

This was a multicenter randomized clinical trial conducted from September 15, 2021, to June 29, 2022, at 27 centers in China. Adult patients 18 years or older with generalized MG were screened, and those who were antibody positive were enrolled.

Intervention

Eligible patients received batoclimab or matching placebo in addition to standard of care. Each treatment cycle consisted of 6 weekly subcutaneous injections of batoclimab, 680 mg, or matching placebo followed by 4 weeks of observation. A second treatment cycle was conducted in patients who required continuing treatment.

Main Outcome and Measure

The primary outcome was sustained improvement, as defined by a 3-point or greater reduction in the Myasthenia Gravis Activities of Daily Living (MG-ADL) score from baseline for 4 or more consecutive weeks in the first cycle in individuals who were positive for acetylcholine receptor or muscle-specific kinase antibodies.

Results

A total of 178 adult patients with generalized MG were screened, 132 were randomly assigned, 131 tested positive for antibodies, and 1 tested negative for antibodies. A total of 132 patients (mean [SE] age, 43.8 [13.6] years; 88 women [67.2%]) were enrolled. The rate of sustained MG-ADL improvement in the first cycle in antibody-positive patients was 31.3% (20 of 64) in the placebo group vs 58.2% (39 of 67) in the batoclimab group (odds ratio, 3.45; 95% CI, 1.62-7.35; P = .001). The MG-ADL score diverged between the 2 groups as early as week 2. The mean (SE) maximum difference in MG-ADL score reduction occurred 1 week after the last dose (day 43, 1.7 [0.3] in the placebo group vs 3.6 [0.3] in the batoclimab group; group difference, -1.9; 95% CI, -2.8 to -1.0; nominal P < .001). The rates of treatment-related and severe treatment-emergent adverse events in patients were 36.9% (24 of 65) and 7.7% (5 of 65) in the placebo group vs 70.1% (47 of 67) and 3.0% (2 of 67) in the batoclimab group, respectively.

Conclusions and Relevance

Batoclimab increased the rate of sustained MG-ADL improvement and was well tolerated in adult patients with generalized MG. Clinical effects and the extent of IgG reduction were similar to those previously reported for efgartigimod and rozanolixizumab. Future studies of large sample size are needed to further understand the safety profile of batoclimab.

Trial Registration

ClinicalTrials.gov Identifier: NCT05039190.

Curcumin protects mice with myasthenia gravis by regulating the gut microbiota, short-chain fatty acids, and the Th17/Treg balance

Curcumin is widely used as a traditional drug in Asia. Interestingly, curcumin and its metabolites have been demonstrated to influence the microbiota. However, the effect of curcumin on the gut microbiota in patients with myasthenia gravis (MG) remains unclear. This study aimed to investigate the effects of curcumin on the gut microbiota community, short-chain fatty acids (SCFAs) levels, intestinal permeability, and Th17/Treg balance in a Torpedo acetylcholine receptor (T-AChR)-induced MG mouse model. The results showed that curcumin significantly alleviated the clinical symptoms of MG mice induced by T-AChR. Curcumin modified the gut microbiota composition, increased microbial diversity, and, in particular, reduced endotoxin-producing Proteobacteria and Desulfovibrio levels in T-AChR-induced gut dysbiosis. Moreover, we found that curcumin significantly increased fecal butyrate levels in mice with T-AChR-induced gut dysbiosis. Butyrate levels increased in conjunction with the increase in butyrate-producing species such as Oscillospira, Akkermansia, and Allobaculum in the curcumin-treated group. In addition, curcumin repressed the increased levels of lipopolysaccharide (LPS), zonulin, and FD4 in plasma. It enhanced Occludin expression in the colons of MG mice induced with T-AChR, indicating dramatically alleviated gut permeability. Furthermore, curcumin treatment corrected T-AChR-induced imbalances in Th17/Treg cells. In summary, curcumin may protect mice against myasthenia gravis by modulating both the gut microbiota and SCFAs, improving gut permeability, and regulating the Th17/Treg balance. This study provides novel insights into curcumin's clinical value in MG therapy.

An angel or a devil? Current view on the role of CD8+ T cells in the pathogenesis of myasthenia gravis

BACKGROUND

Myasthenia gravis (MG) and the experimental autoimmune MG (EAMG) animal model are characterized by T-cell-induced and B-cell-dominated autoimmune diseases that affect the neuromuscular junction. Several subtypes of CD4+ T cells, including T helper (Th) 17 cells, follicular Th cells, and regulatory T cells (Tregs), contribute to the pathogenesis of MG. However, increasing evidence suggests that CD8+ T cells also play a critical role in the pathogenesis and treatment of MG.

MAIN BODY

Herein, we review the literature on CD8+ T cells in MG, focusing on their potential effector and regulatory roles, as well as on relevant evidence (peripheral, in situ, cerebrospinal fluid, and under different treatments), T-cell receptor usage, cytokine and chemokine expression, cell marker expression, and Treg, Tc17, CD3+CD8+CD20+ T, and CXCR5+ CD8+ T cells.

CONCLUSIONS

Further studies on CD8+ T cells in MG are necessary to determine, among others, the real pattern of the Vβ gene usage of autoantigen-specific CD8+ cells in patients with MG, real images of the physiology and function of autoantigen-specific CD8+ cells from MG/EAMG, and the subset of autoantigen-specific CD8+ cells (Tc1, Tc17, and IL-17+IFN-γ+CD8+ T cells). There are many reports of CD20-expressing T (or CD20 + T) and CXCR5+ CD8 T cells on autoimmune diseases, especially on multiple sclerosis and rheumatoid arthritis. Unfortunately, up to now, there has been no report on these T cells on MG, which might be a good direction for future studies.

The Efficacy and Safety of Different Targeted Drugs for the Treatment of Generalized Myasthenia Gravis: A Systematic Review and Bayesian Network Meta-analysis

BACKGROUND

The treatment of generalized myasthenia gravis (gMG) has been transformed by the development and approval of new targeted therapies. This analysis aimed to rank and compare the new therapies for gMG using efficacy and safety data from randomized controlled trials (RCTs).

METHODS

We searched PubMed, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov (up to November 2022) for RCTs of targeted drugs for gMG. We used a Bayesian random-effects network meta-analysis (NMA) model and a Markov chain Monte Carlo (MCMC) model for statistical analysis. The primary outcome was the change in quantitative myasthenia gravis score (QMGS) from baseline, while the secondary outcome was the risk ratio (RR) of adverse events (AEs) during treatment. The surface under the cumulative ranking curve (SUCRA) was used to rank these targeted drugs, with higher SUCRA values indicating better efficacy or lower likelihood of AEs.

RESULTS

In total, 13 studies (872 subjects) were included in this analysis evaluating 10 targeted drugs (batoclimab, belimumab, CFZ533, eculizumab, efgartigimod, nipocalimab, rituximab, ravulizumab, rozanolixizumab, and zilucoplan). With regards to the primary outcome, batoclimab [standardized mean difference (SMD), - 1.61; 95% credible interval (CrI), - 2.78, - 0.43] significantly reduced QMGS in patients with gMG when compared with placebo and was ranked as the most efficacious drug. Ranked second and third were eculizumab (SMD, - 0.67; 95% CrI, 1.43, 0.01) and zilucoplan (SMD, - 0.54; 95% CrI, - 1.56, 0.46), respectively. Nipoclimab (SMD, - 0.02; 95% CrI, - 1.04, 1.00) had the worst efficacy and ranked last among all targeted drugs. In our study, except for batoclimab, there was no statistically significant difference in the reduction of patient QMGS for the remaining targeted agents compared with placebo. With regards to the secondary outcomes, only batoclimab (RR, 0.19; 95% CrI, 0, 0.97) led to a significant reduction in the incidence of AEs when compared with the placebo. Belimumab (RR, 0.85; 95% CrI, 0.57, 1.19), CFZ533 (RR, 0.95; 95% CrI, 0.72, 1.25), eculizumab (RR, 0.99; 95% CrI, 0.85, 1.21), and efgartigimod (RR, 0.93; 95% CrI, 0.76, 1.15) also led to a lower incidence of AEs, although these effects were not significantly different from the placebo.

CONCLUSIONS

Batoclimab had the best efficacy and safety for the treatment of gMG and was ranked first out of the 10 targeted drugs included in this study. Eculizumab was ranked second, and nipocalimab had the worst efficacy. With the exception of batoclimab, the incidence of AEs for the remaining drugs was not statistically significantly different from placebo. We note, however, that wide CrIs reflect the uncertainty in this analysis owing to the small number of available studies and low numbers of study participants; moreover, batoclimab had the widest CrI of all drugs in this analysis. More well-designed studies with long-term follow-up are needed to further evaluate and compare the efficacy and safety of these drugs in the future.

Bidirectional association between hypothyroidism and myasthenia gravis: a Mendelian randomized study

OBJECTIVES

Although observational studies have suggested a link between hypothyroidism and myasthenia gravis (MG), a causal relationship has not been established. We aimed to investigate the causal association using a two-sample Mendelian randomization (MR) study.

METHODS

Using summary statistics from genome-wide association studies involving 494,577 and 38,243 individuals, single-nucleotide polymorphisms exhibiting no linkage disequilibrium (r2 ≤ 0.001) and displaying significant differences (p ≤ 5 × 10-8) were selected for hypothyroidism and MG. To assess the potential causality relationship between hypothyroidism and MG, MR analysis was conducted using inverse variance weighted (IVW), weighted median method, and MR-Egger. The MR-Egger regression, heterogeneity test, pleiotropy test, and leave-one-out sensitivity test were employed to examine sensitivity analyses. In addition, validation datasets were used to validate the relevant results.

RESULTS

Genetic liability to hypothyroidism was positively associated with MG (IVW, OR: 1.36, 95% CI: 1.17-1.58, p = 7.53 × 10-05; weighted median, OR: 1.19, 95% CI: 0.70-2.02, p = 0.522; MR-Egger, OR: 1.19, 95% CI: 0.98-1.45, p = 0.080). Among the three MR methods, the correlation between hypothyroidism and MG genetic prediction was consistent. The independent validation set (IVW, OR: 466.47, 95% CI: 4.70 -46,285.95, p = 0.01) further supported this. Additionally, bidirectional studies showed that using IVW, there was no reverse causality (OR: 1.104, 95%CI: 0.96-1.27, p = 0.170).

DISCUSSION

This MR study showed that hypothyroidism can increase the risk of MG. Further investigation into the underlying mechanisms of this potential causality is warranted to offer novel therapeutic options for MG in the future.

Therapeutic effect of ofatumumab in patients with myasthenia gravis: immunoregulation of follicular T helper cells and T helper type 17 cells

Introduction

This study aimed to study the therapeutic effects of ofatumumab in patients with myasthenia gravis (MG) in addition to the immunomodulatory effects on peripheral follicular T helper (Tfh) cells and T helper type 17 (Th17) cells.

Methods

Thirty-one patients with anti-acetylcholine receptor (AChR) antibody-positive MG were included in this study. At weeks 0, 1, 2, and 4, an initial dose of 20 mg of ofatumumab was injected subcutaneously, with a 2-month follow-up after completing this first cycle. At baseline, 1 month, and 3 months, we assessed the Quantitative MG (QMG), 15-item MG-Quality of Life (MG-QOL15), and MG-Activities of Daily Living (MG-ADL) scales and measured the frequencies of Tfh, Th17, and B cells and the levels of anti-AChR antibody, IL-6, IL-21, and IL-17 in the peripheral blood.

Results

At 1 month and 3 months, the QMG, MG-QOL15, and MG-ADL scores were all significantly reduced. At 3 months, doses of prednisone were reduced by an average of 37%. Decreased frequencies of Tfh and Th17 cells, depletion of B cells, and reduced levels of IL-6, IL-21, and IL-17 were all observed at 1 month or 3 months.

Discussion

Therefore, the therapeutic effect of ofatumumab could be detected after one cycle of treatment, which was maintained for 2 months. The immunomodulatory effect of ofatumumab during the observation period may involve depletion of B cells, reduction of Tfh and Th17 cells frequencies, and reduced levels of IL-6, IL-21, and IL-17. The findings provide novel data for the potential application of ofatumumab in MG.

Residual serum fibrinogen as a universal biomarker for all serotypes of Myasthenia gravis

Myasthenia Gravis (MG) is an autoimmune disease associated with severe neuromuscular weakness. Diagnostic confirmation of MG is typically delayed and secured in about 85% and 50% of patients with generalized and ocular MG, respectively with serum antibodies. We have identified a sensitive and specific diagnostic biomarker for various MG serotypes with quantitative proteomics. Serum proteomes of 18 individuals (MG patients, healthy controls (HC), Rheumatoid Arthritis (RA) were quantified in a pilot study and occurrence of high residual fibrinogen was validated by immunoblotting and further investigated by targeted mass spectrometry on the sera of 79 individuals (31 MG of various serotypes, 30 HC, 18 RA). Initial proteomic analysis identified high residual fibrinogen in MG patient sera which was then validated by antibody-based testing. Subsequently, a blinded study of independent samples showed 100% differentiation of MG patients from controls. A final serological quantification of 14 surrogate peptides derived from α-, β-, and γ-subunits of fibrinogen in 79 individuals revealed fibrinogen to be highly specific and 100% sensitive for MG (p < 0.00001), with a remarkable average higher abundance of > 1000-fold over control groups. Our unanticipated discovery of high levels of residual serum fibrinogen in all MG patients can secure rapid bedside diagnosis of MG.

Myasthenia gravis: Molecular mechanisms and promising therapeutic strategies

Myasthenia gravis (MG) is a type of autoimmune disease caused by the blockage of neuromuscular junction transmission owing to the attack of autoantibodies on transmission-related proteins. Related antibodies, such as anti-AChR, anti-MuSK and anti-LRP4 antibodies, can be detected in most patients with MG. Although traditional therapies can control most symptoms, several challenges remain to be addressed, necessitating the development of more effective and safe treatment strategies for MG. With the in-depth exploration on the mechanism and immune targets of MG, effective therapies, especially therapies using biologicals, have been reported recently. Given the important roles of immune cells, cytokines and intercellular interactions in the pathological process of MG, B-cell targeted therapy, T-cell targeted therapy, proteasome inhibitors targeting plasma cell, complement inhibitors, FcRn inhibitors have been developed for the treatment of MG. Although these novel therapies exert good therapeutic effects, they may weaken the immunity and increase the risk of infection in MG patients. This review elaborates on the pathogenesis of MG and discusses the advantages and disadvantages of the strategies of traditional treatment and biologicals. In addition, this review emphasises that combined therapy may have better therapeutic effects and reducing the risk of side effects of treatments, which has great prospects for the treatment of MG. With the deepening of research on immunotherapy targets in MG, novel opportunities and challenges in the treatment of MG will be introduced.

Extracellular vesicles encapsulated with caspase-1 inhibitor ameliorate experimental autoimmune myasthenia gravis through targeting macrophages

Cysteinyl aspartate-specific proteinase-1 (caspase-1) is a multifunctional inflammatory mediator in many inflammation-related diseases. Previous studies show that caspase-1 inhibitors produce effective therapeutic outcomes in a rat model of myasthenia gravis. However, tissue toxicity and unwanted off-target effects are the major disadvantages limiting their clinical application as therapeutic agents. This study shows that dendritic cell-derived extracellular vesicles (EVs) loaded with a caspase-1 inhibitor (EVs-VX-765) are phagocytized mainly by macrophages, and caspase-1 is precisely expressed in macrophages. Furthermore, EVs-VX-765 demonstrates excellent therapeutic effects through a macrophage-dependent mechanism, and it notably inhibits the level of interleukin-1β and subsequently inhibits Th17 response and germinal center (GC) reactions. In addition, EVs-VX-765 demonstrates better therapeutic effects than routine doses of VX-765, although drug loading is much lower than routine doses, consequently reducing tissue toxicity. In conclusion, this study's findings suggest that EV-mediated delivery of caspase-1 inhibitors is effective for treating myasthenia gravis and is promising for clinical applications.

Rituximab treatment in myasthenia gravis

Myasthenia gravis (MG) is a chronic autoimmune disease mediated by antibodies against post-synaptic proteins of the neuromuscular junction. Up to 10%-30% of patients are refractory to conventional treatments. For these patients, rituximab has been used off-label in the recent decades. Rituximab is a monoclonal antibody against the CD20 protein that leads to B cell depletion and to the synthesis of new antibody-secreting plasma cells. Although rituximab was created to treat B-cell lymphoma, its use has widely increased to treat autoimmune diseases. In MG, the benefit of rituximab treatment in MuSK-positive patients seems clear, but a high variability in the results of observational studies and even clinical trials has been reported for AChR-positive patients. Moreover, few evidence has been reported in seronegative MG and juvenile MG and some questions about regimen of administration or monitoring strategies, remains open. In this review, we intend to revise the available literature on this topic and resume the current evidence of effectiveness of Rituximab in MG, with special attention to results on every MG subtype, as well as the administration protocols, monitoring strategies and safety profile of the drug.

Objectivity, practicality, and significance of practice guidelines for the practicing neurologists: What we learnt from consensus criteria in CIDP, Myasthenia Gravis and Inflammatory Myopathies

The value of practice guidelines in the three most common autoimmune neuromuscular disorders, namely Chronic Inflammatory Demyelinating Polyneuropathy (CIDP), Myasthenia Gravis (MG) and Autoimmune Inflammatory Myopathies (AIM), has been extensively debated regarding their usefulness in clinical practice, objectivity and universal value considering that guidelines are also established regionally in certain countries. This commentary highlights common concerns on how guidelines are presently generated, pointing out: (a) non-sufficient diversity among Task-Force members to identify and address not only routine clinical and electrophysiology issues but also immunology, imaging, pathology, biomarkers, epidemiology or treatment economics; (b) Task-Force being often comprised by the same or seemingly like-minded members conveying the erroneous impression that experts with opposing views might have been excluded, even if this is clearly not the case; and (c) relying on web-based registries or retrospective data collections from heterogeneous sources. As a result, the existing practice guidelines in CIDP, MG and AIM remain an unfinished business but an excellent base for further enhancement. Guidelines can be extremely helpful not only for clinical trials but also in clinical practice if viewed as a living document with continuously updated versions by experts even with opposing views with precise information on diagnostics, pathomechanisms, therapeutic schemes, evolving biomarkers and economics of new therapies with validation of the post-guidelines criteria. Geographic diversity should be taken into consideration because the availability of biomarker testing, and therapies differ among countries. Patient preferences need to be also considered in therapeutic guidelines because newly marketed drugs offer more options steadily changing the therapeutic algorithms in autoimmune neuromuscular diseases generating also questions as to whether they also influence decisions on insurance coverage. Collectively, these startup considerations are aimed to make practice guidelines more objective, widely acceptable worldwide and more practical or easier to follow in clinical practice.

Cytokines Single Nucleotide Polymorphisms (SNPs) Association With Myasthenia Gravis (MG) In Algerian Patients: A Case-Control Study On A Small Group

ABSTRACT

Myasthenia gravis (MG) is an autoimmune disease of multifactorial etiology in which genetic factors and cytokines seem to play an important role. The aim of this study was to investigate potential associations of cytokines single nucleotide polymorphisms (SNPs) and MG in Algerian patients. We performed a case-control study that included 27 patients and 74 healthy subjects. Cytokines SNPs genotyping was performed by the polymerase chain reaction sequence-specific primers (PCR-SSP) method. Our results showed that the TNF-α -308G/A (P < 0.005) and TGF-β1 +869T/T (P < 0.05) genotypes were more frequent among patients with MG compared with healthy individuals, whereas TNF-α -308G/G (P < 0.0001), TGF-β1 +869T/C (P < 0.05), and IFN-γ +874A/A (P < 0.05) were less frequent. Our results also showed that IL-10 and IL-6 SNPs did not show any significant difference in distribution between MG patients and healthy individuals. Our observations support the hypothesis that implicates genetic variants of certain cytokines in MG. However, ours results should be replicated with a larger sample size. In addition, the precise underlying processes remain to be clarified.

HIGHLIGHTS

TNF-α -308G/A and TGF-β1 +869T/C genotypes predispose to MG.IFN-γ +874A/A genotype protects against MG.IL-6 -174C/G SNP is not associated with MG.

FcRN receptor antagonists in the management of myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disorder characterized by autoantibodies specifically directed against proteins located within the postsynaptic membrane of the neuromuscular junction. These pathogenic autoantibodies can be reduced by therapies such as plasma exchange, IVIG infusions and other immunosuppressive agents. However, there are significant side effects associated with most of these therapies. Since there is a better understanding of the molecular structure and the biological properties of the neonatal Fc receptors (FcRn), it possesses an attractive profile in treating myasthenia gravis. FcRn receptors prevent the catabolism of IgG by impeding their lysosomal degradation and facilitating their extracellular release at physiological pH, consequently extending the IgG half-life. Thus, the catabolism of IgG can be enhanced by blocking the FcRn, leading to outcomes similar to those achieved through plasma exchange with no significant safety concerns. The available studies suggest that FcRn holds promise as a versatile therapeutic intervention, capable of delivering beneficial outcomes in patients with distinct characteristics and varying degrees of MG severity. Efgartigimod is already approved for the treatment of generalized MG, rozanolixizumab is under review by health authorities, and phase 3 trials of nipocalimab and batoclimab are underway. Here, we will review the available data on FcRn therapeutic agents in the management of MG.

An evaluation of rozanolixizumab-noli for the treatment of anti-AChR and anti-MuSK antibody-positive generalized myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) is an auto-immune disease characterized by fluctuating symptoms of muscle weakness and fatigue. Corticosteroids and corticosteroid-sparing broad-spectrum immunosuppression play a great role in the treatment of myasthenia gravis. However, debilitating side effects and long time to treatment effect highlight the need for development of novel target-specific medications. Rozanolixizumab is a highly specific neonatal Fc receptor (FcRn) inhibitor that acts on immunoglobulin G (IgG) homeostasis. Results from the MycarinG Phase III randomized controlled trial demonstrated significant efficacy of rozanolixizumab in generalized MG in terms of primary outcome and all secondary endpoints, tolerability, and safety compared to placebo.

AREAS COVERED

We included different trials on myasthenia gravis and rozanolixizumab which include Phase II (NCT03052751) and Phase III MycarinG (NCT03971422) studies.

EXPERT OPINION

Clinical trials have demonstrated that rozanolixizumab has strong efficacy with a 78% reduction in pathogenic IgG like plasma exchange (PLEX) and has therapeutic benefits comparable with PLEX and IVIG. It has less treatment adverse events and is easily accessible through subcutaneous infusion. The safety and effectiveness of rozanolixizumab need to be assessed further in the real-world context in post-marketing studies. If current trial information holds true, rozanolixizumab may become a medication of choice for MG in succeeding years.

Clinical and immune-related factors associated with exacerbation in adults with well-controlled generalized myasthenia gravis

Objectives

To describe the clinical predictors and immune-related factors for exacerbation in adults with well-controlled generalized myasthenia gravis (GMG).

Methods

We conducted a retrospective analysis of 585 adults with well-controlled GMG from our institution to explore the risk factors for exacerbation. Furthermore, propensity score matching (PSM) was used to compare the proportions of lymphocyte subsets, and the levels of immunoglobulin, complement, and anti-acetylcholine receptor antibody (AChR-ab) in the peripheral blood of 111 patients with exacerbations and 72 patients without exacerbations.

Results

A total of 404 patients (69.1%) experienced at least one exacerbation, and the median (interquartile range) time to the first exacerbation was 1.5 years (0.8-3.1 years). Multivariable Cox regression analysis showed that age at onset, disease duration before enrollment, Myasthenia Gravis Foundation of America classification (MGFA) class III vs. class II, MGFA class IV-V vs. class II, AChR-ab levels, anti-muscle specific kinase antibody levels, thymus hyperplasia, prednisone plus immunosuppressants vs. prednisone treatment, and thymectomy were independent predictors for exacerbations [hazard ratio (HR) = 1.011, 1.031, 1.580, 1.429, 2.007, 2.033, 1.461, 0.798, and 0.651, respectively]. Propensity-matched analysis compared 51 patient pairs. After PSM, the peripheral blood proportions of CD3^-CD19⁺ B cells, ratios of CD3⁺CD4⁺/CD3⁺CD8⁺ T cells, and AChR-ab levels were significantly increased, and the peripheral blood proportions of CD3⁺CD8⁺ T and CD4⁺CD25⁺CD127^low+ regulatory T cells (Tregs) were significantly lower in patients with exacerbation than in those without exacerbation (all p < 0.05).

Conclusion

Myasthenia gravis (MG) exacerbations were more frequent in those patients with older onset age, longer disease duration, more severe MGFA classification, positive AChR-ab, and lack of combined immunotherapy or thymectomy treatment. On the other hand, CD3^-CD19⁺ B cells, CD3⁺CD8⁺ T cells, Tregs, and AChR-ab in peripheral blood may be involved in the course of GMG exacerbation.

Impact of Early Treatment with Intravenous High-Dose Methylprednisolone for Ocular Myasthenia Gravis

The efficacy of intravenous high-dose methylprednisolone (IVMP) in ocular myasthenia gravis (MG) has not been fully established. This study aimed to elucidate the effects of early intervention with IVMP for achieving the therapeutic targets (minimal manifestations [MM] or MM or better status with prednisolone ≤ 5 mg/day [MM5mg]) in ocular MG. In this observational study, we included a total of 1710 consecutive patients with MG enrolled in the Japan MG Registry in 2021. Of these, 204 patients with ocular MG who received immunotherapy were analyzed. The clinical course and time to first achieve MM or MM5mg after starting immunotherapy were compared between the early IVMP group (treated with IVMP within 3 months of treatment initiation) and the non-early IVMP group. Despite having greater clinical severity before immunotherapy and lower oral prednisolone doses throughout the course, the early IVMP group (n = 55) showed a higher rate of achievement of MM (P = 0.0040, log-rank test; hazard ratio 1.58, 95% confidence interval [CI] 1.13-2.20, P < 0.0001) and MM5mg (P = 0.0005, log-rank test; hazard ratio 1.78, 95% CI 1.27-2.51, P < 0.0001) compared with the non-early IVMP group (n = 149). In conclusion, an early intervention with IVMP is likely to increase the probability of achieving a better long-term outcome and reducing the total dose of corticosteroids in ocular MG.

Biological therapies for myasthenia gravis

INTRODUCTION

Recently, treatments for myasthenia gravis (MG) have progressed significantly. Symptoms of some patients with refractory MG are not relieved by conventional therapies, and such patients might benefit from novel biological treatments that are being developed.

AREAS COVERED

We review several novel biological therapies for MG, such as complement inhibitors, neonatal Fc receptor inhibitors, anti-B cell drugs, and IL-6 receptor inhibitors. We also report the modes of action, efficacy, safety, and tolerability of these drugs.

EXPERT OPINION

Several biological therapies have been developed for MG, and these biologics are promising agents for treating refractory MG. Establishing biomarkers and accumulating evidence of therapeutic response is required to provide the most appropriate biological treatment for each patient.

Risk factors for postoperative myasthenia gravis in patients with thymoma without myasthenia gravis: A systematic review and meta-analysis

Introduction

According to the principle, thymomas combined with myasthenia gravis (MG) require surgical treatment. However, patients with non-MG thymoma rarely develop MG and early- or late-onset MG after surgery is called postoperative MG (PMG). Our study used a meta-analysis to examine the incidence of PMG and risk factors.

Methods

Relevant studies were searched for in the PubMed, EMBASE, Web of Science, CNKI,and Wanfang databases. Investigations that directly or indirectly analyzed the risk factors for PMG development in patients with non-MG thymoma were included in this study. Furthermore, risk ratios (RR) with 95% confidence intervals (CI) were pooled using meta-analysis, and fixed-effects or random-effects models were used depending on the heterogeneity of the included studies.

Results

Thirteen cohorts containing 2,448 patients that met the inclusion criteria were included. Metaanalysis revealed that the incidence of PMG in preoperative patients with non-MG thymoma was 8%. Preoperative seropositive acetylcholine receptor antibody (AChR-Ab) (RR = 5.53, 95% CI 2.36 - 12.96, P<0.001), open thymectomy (RR =1.84, 95% CI 1.39 - 2.43, P<0.001), non-R0 resection (RR = 1.87, 95% CI 1.36 - 2.54, P<0.001), world health organization (WHO) type B (RR =1.80, 95% CI 1.07 - 3.04, P= 0.028), and postoperative inflammation (RR = 1.63, 95% CI 1.26 - 2.12, P<0.001) were the risk factors for PMG in patients with thymoma. Masaoka stage (P = 0.151) and sex (P = 0.777) were not significantly associated with PMG.

Discussion

Patients with thymoma but without MG had a high probability of developing PMG. Although the incidence of PMG was very low, thymectomy could not completely prevent the occurrence of MG. Preoperative seropositive AChR-Ab level, open thymectomy, non-R0 resection, WHO type B, and postoperative inflammation were risk factors for PMG.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022360002.

B cell-specific mAb-siRNA conjugates improve experimental myasthenia

Myasthenia gravis (MG) is a debilitating autoimmune disease characterized by muscle fatigue and weakness caused by autoantibody- and complement-mediated damage to the neuromuscular junction. This study sought to compare the efficacy of unique sets of monoclonal antibody-siRNA conjugates, individually (mono) or in combination (duo), against the crucial receptors predominantly or solely expressed on two subsets of B cells-plasma B cells and their precursor (transitional mature B) cells in a mouse model of MG. At the optimized doses, the conjugates, likely due to the combined activities of mAb and siRNA, substantially decreased the expression levels of CD268 (B cell-activating factor receptor) in mature B cells and CD269 (B-cell maturation antigen) in plasma cells concomitantly with reducing the levels of acetylcholine receptor (AChR)-specific autoantibodies. PEGylation, but not pretreatment with an antibody against type 1 interferon receptor, further improved duoconjugate-induced reduction in the autoantibody levels. Our results show that the duoconjugate treatment significantly improved the clinical symptoms of MG, consistent with the preservation of bungarotoxin-bound functional AChRs. In the future, developing similar target-specific combination molecules can potentially turn into a new and effective therapeutic approach for MG.

Blocking interleukin-23 ameliorates neuromuscular and thymic defects in myasthenia gravis

Acetylcholine receptor (AChR) myasthenia gravis (MG) is a chronic autoimmune disease characterized by muscle weakness. The AChR⁺ autoantibodies are produced by B-cells located in thymic ectopic germinal centers (eGC). No therapeutic approach is curative. The inflammatory IL-23/Th17 pathway is activated in the thymus as well as in the blood and the muscle, contributing to the MG pathogenic events. We aimed to study a potential new therapeutic approach that targets IL-23p19 (IL-23) in the two complementary preclinical MG models: the classical experimental MG mouse model (EAMG) based on active immunization and the humanized mouse model featuring human MG thymuses engrafted in NSG mice (NSG-MG). In both preclinical models, the anti-IL-23 treatment ameliorated MG clinical symptoms. In the EAMG, the treatment reduced IL-17 related inflammation, anti-AChR IgG2b antibody production, activated transduction pathway involved in muscle regeneration and ameliorated the signal transduction at the neuromuscular junction. In the NSG-MG model, the treatment reduced pathogenic Th17 cell population and expression of genes involved in eGC stabilization and B-cell development in human MG thymus biopsies. Altogether, these data suggest that a therapy targeting IL-23p19 may promote significant clinical ameliorations in AChR⁺ MG disease due to concomitant beneficial effects on the thymus and skeletal muscle defects.

Immunological Aspects of Von Hippel-Lindau Disease: A Focus on Neuro-Oncology and Myasthenia Gravis

Von Hippel-Lindau (VHL) disease is an autosomal dominant condition that predisposes affected individuals to a variety of malignant and benign neoplasms. The pathogenetic turning point of this illness is the accumulation of hypoxia-inducible factor (HIF)-1α, a transcription factor of several genes involved in oncogenesis, angiogenesis, tissue regeneration, metabolic regulation, hematopoiesis, and inflammatory responses. From an oncological perspective, increased awareness of the molecular pathways underlying this disease is bringing us closer to the development of specific and targeted therapies. Meanwhile, on the surgical side, improved understanding can help to better identify the patients to be treated and the surgical timing. Overall, pathogenesis research is crucial for developing patient-tailored therapies. One of the actual key topics of interest is the link between the VHL/HIF axis and inflammation. The present study aims to outline the fundamental mechanisms that link VHL disease and immune disorders, as well as to explore the details of the overlap between VHL disease and myasthenia gravis (MG) pathogenetic pathways. As a result, MG becomes a paradigm for autoimmune disorders that might be related with VHL disease.

Comparison of Fixed and Live Cell-Based Assay for the Detection of AChR and MuSK Antibodies in Myasthenia Gravis

BACKGROUND AND OBJECTIVES

Live cell-based assay (CBA) can detect acetylcholine receptors (AChRs) or muscle-specific tyrosine kinase (MuSK) antibodies (Abs) in a proportion of patients with radioimmunoassay (RIA)-double seronegative myasthenia gravis (dSN-MG). A commercial fixed CBA for AChR and MuSK Abs has recently become available; however, comparative studies on fixed and live CBAs are lacking. In this study, we compared the performance of fixed and live CBAs in patients with RIA-dSN MG and assessed their sensitivity in RIA-positive MG samples and their specificity.

METHODS

AChR and MuSK Abs were tested in 292 serum samples from 2 Italian MG referral centers by live and fixed CBAs: 192 from patients with MG and 100 from controls. All samples had been previously assessed by RIA: 66 were AChR positive, 40 MuSK positive, and 86 dSN. All controls were negative. Two independent raters assessed the CBA results. Fixed and live CBAs were compared with the McNemar test; interrater and interlaboratory agreement were assessed with Cohen's kappa or interclass correlation coefficient (ICC), as appropriate.

RESULTS

In 86 RIA-dSN samples, fixed CBA detected Abs in 10 cases (11.6%, 95% CI 5.7-20.3), whereas live CBA detected Abs in 16 (18.6%, 95% CI 11.0-28.5) (p = 0.0143). Of these sera, those positive by fixed CBA were also positive by live CBA. In addition, live CBA could detect MuSK Abs in 4 and AChR Abs in 2 samples that were negative by fixed CBA, providing an 8% (95% CI 2.9-16.6) further increase in the Ab detection rate. These results were confirmed by flow cytometry. In the RIA-positive cohort, the sensitivity for AChR Abs was 98.5% (95% CI 91.9%-99.9%) for fixed CBA and 100% (95% CI 94.6-100) for live CBA (p = 0.1573). For both assays, the sensitivity for MuSK Abs was 100% (95% CI 91.2-100), and the specificity was 100% (95% CI 96.4-100). Interrater agreement was almost perfect for live and fixed CBAs (Cohen's kappa 0.972 and 0.978, respectively), alike interlaboratory agreement. Interrater agreement for the CBA score ranged from good to excellent (ICC: 0.832-0.973).

DISCUSSION

Fixed CBA represents a valuable alternative to RIA for AChR and MuSK Ab detection in patients with MG and could be considered as a first-step diagnostic test. Live CBA can be useful in the serologic evaluation of RIA- and fixed CBA-negative samples.