Advances and ongoing research in the treatment of autoimmune neuromuscular junction disorders

A class of chemical compounds enhances clustering of muscle nicotinic acetylcholine receptor in cultured myogenic cells

Neuromuscular signal transmission is affected in various diseases including myasthenia gravis, congenital myasthenic syndromes, and sarcopenia. We used an ATF2-luciferase system to monitor the phosphorylation of MuSK in HEK293 cells introduced with MUSK and LRP4 cDNAs to find novel chemical compounds that enhanced agrin-mediated acetylcholine receptor (AChR) clustering. Four compounds with similar chemical structures carrying benzene rings and heterocyclic rings increased the luciferase activities 8- to 30-folds, and two of them showed continuously graded dose dependence. The effects were higher than that of disulfiram, a clinically available aldehyde dehydrogenase inhibitor, which we identified to be the most competent preapproved drug to enhance ATF2-luciferase activity in the same assay system. In C2C12 myotubes, all the compounds increased the area, intensity, length, and number of AChR clusters. Three of the four compounds increased the phosphorylation of MuSK, but not of Dok7, JNK. ERK, or p38. Monitoring cell toxicity using the neurite elongation of NSC34 neuronal cells as a surrogate marker showed that all the compounds had no effects on the neurite elongation up to 1 μM. Extensive docking simulation and binding structure prediction of the four compounds with all available human proteins using AutoDock Vina and DiffDock showed that the four compounds were unlikely to directly bind to MuSK or Dok7, and the exact target remained unknown. The identified compounds are expected to serve as a seed to develop a novel therapeutic agent to treat defective NMJ signal transmission.

Worsening of myasthenic symptoms associated with statins

INTRODUCTION/AIMS

The common presentations of statin intolerance are muscle-specific symptoms. Although statins are one type of drug reported to cause myasthenic worsening, myasthenic worsening has not been recognized as statin intolerance. The purpose of the present study is to investigate in a large cohort the safety profiles of statins in patients with myasthenia gravis (MG).

METHODS

A total of 1710 consecutive patients with MG who visited sites associated with the Japan MG registry 2021 group between April and October 2021 were reviewed. Statin-associated myasthenic worsening was defined as worsening of any myasthenic symptoms on statin use and improvement of the symptom by stopping the statin or by undertaking additional treatment with patient and doctor confirmation.

RESULTS

Among the 400 patients who used statins, 8 (2%) patients experienced statin intolerance and 6 (1.5%) patients experienced myasthenic worsening. No patients developed MG on the statin. Ptosis was a main symptom of myasthenic worsening in 4 (67%) patients. Atorvastatin was used in all patients with statin-associated myasthenic worsening. The symptoms of statin intolerance and statin-associated myasthenic worsening were improved within 2 months and 3 months, respectively, in all patients by cessation of statin use.

DISCUSSION

Regarding statin-associated myasthenic worsening, prevalence was low, and severity was mild; with cessation of statin use, symptoms improved within a few months, and outcomes were generally good. Although statins can be used in MG patients with little concern, statin-associated myasthenic worsening should be noted in addition to the classical statin intolerance associated with statin use.

Immunological and therapeutic insights in autoimmune autonomic ganglionopathy: What is the position of apheresis in immunotherapy?

Autoimmune autonomic ganglionopathy (AAG) is characterized by various autonomic and extra-autonomic symptoms and is caused by autoantibodies against nicotinic acetylcholine receptors present in the autonomic ganglia (ganglionic acetylcholine receptor, gAChR), requiring immediate and aggressive intervention to prevent the exacerbation of symptoms. However, there is currently no internationally accepted standard of care for the immunotherapy of AAG, including apheresis. Although the rationale for the use of plasma exchange (PLEX) in AAG is strong, whereby pathogenic gAChR antibodies are removed, its overall impact on patient outcomes is not well-established. Based on previous case reports and small case series studies, we provide a comprehensive overview of the challenges and uncertainties surrounding the use of PLEX for the management of AAG and provide current practice recommendations to guide treatment decisions.

Short-term changes in serum miRNA levels and patient-reported clinical outcomes in myasthenia gravis

INTRODUCTION/AIMS

The circulating microRNAs (miRNAs) miR-150-5p, miR-30e-5p, and miR-21-5p have been suggested as potential biomarkers for myasthenia gravis (MG); however, the relationships between short-term natural changes of the miRNAs and patient-reported MG outcome scores have not been well-studied. We assessed the short-term fluctuations in miRNA levels and patient-reported outcome measures in MG.

METHODS

This prospective cohort study included 39 MG patients with regular follow-ups and unchanged medications at the Neurology outpatient clinic at Uppsala University Hospital. Patients had weekly follow-up visits for 1 month, at which blood samples were drawn, and scores from MG activities of daily living (MG-ADL), MG quality-of-life-15 (MG-QoL15), and Fatigue Severity Scale (FSS) were assessed. Serum levels of miRNA miR-150-5p, miR-30e-5p, and miR-21-5p were analyzed using quantitative real-time PCR.

RESULTS

Intra-individual levels of miR-30e-5p and miR-150-5p were stable, whereas a significant reduction in miR-21-5p was observed from week 1 to week 2 (p = .0024) and from week 2 to week 3 (p < .0001). There were intra-individual differences over a short time in MG-ADL, with higher scores in female patients (p = .0281) and a significant reduction from the first to the second weeks (p = .0281), whereas MG-QoL15 and FSS scores were stable.

DISCUSSION

The suggested MG biomarkers miR-30e-5p and miR-150-5p were more stable than miR-21-5p over a short time, indicating their short-term stability as biomarkers. Prospective multi-center studies with longer periods of follow-up and matched controls are needed to validate these miRNAs as biomarkers in MG.

Baricitinib as a treatment for myasthenia gravis: a case report

Myasthenia gravis (MG) is an autoimmune disease that targets neuromuscular junctions. While immunotherapy remains the cornerstone of treatment, the effects of Janus kinase (JAK) inhibitors on MG remain underexplored. In this report, we describe the case of a 58-year-old woman with ocular myasthenia gravis who received treatment with the JAK inhibitor, baricitinib for alopecia areata. The patient presented with left eyelid ptosis and an inadequate response to steroids and pyridostigmine, along with symptoms of alopecia areata. Following diagnosis, we initiated a treatment regimen consisting of baricitinib for six months. After initiation of baricitinib, we observed a complete resolution of the patient's MG symptoms, accompanied by hair regrowth, even when steroids were tapered and pyridostigmine was discontinued. Furthermore, the titer of the anti-acetylcholine receptor antibody was decreased. This report represents the first reported case of anti-acetylcholine receptor antibody-positive MG that was successfully treated through the inhibition of JAK activity.

Induction cyclophosphamide with maintenance immunosuppression in high-risk myasthenia gravis: long-term follow-up and safety profile

BACKGROUND

Patients with refractory or high-risk myasthenia gravis (MG) respond poorly to conventional immunosuppressive therapy, requiring rescue therapies and often experiencing treatment toxicity. Rescue and injectable therapies do not induce remission and require repetitive administration leading to significant constraints on patients and the healthcare system. This long-term follow-up study demonstrates cyclophosphamide as a rapidly effective and safe treatment in patients with refractory or high-risk MG.

METHODS

Retrospective cohort study of MG patients treated with cyclophosphamide between January 2000 and June 2022 conducted at a quaternary neuroimmunology clinic in New South Wales, Australia.

RESULTS

31 patients were treated: mean age of 64 years; median follow-up 3.6 years (5 months to 11 years); 94% seropositive to acetylcholine receptor (AChR) antibodies and 45% had thymoma. A reduced intensity cyclophosphamide induction protocol followed by oral antiproliferative maintenance is described.Median myasthenia gravis composite scores reduced by >50% after the third cycle of cyclophosphamide. Complete cessation of prednisolone was possible in 11 patients while 20 remained on prednisolone with a median daily dose of 5 mg. Plasma exchange was ceased in 62% of patients and intravenous immunoglobulin ceased in 55%. Cyclophosphamide was generally well tolerated with mild cytopenias. There were no malignancies or cases of haemorrhagic cystitis.

CONCLUSION

We describe a large cohort of high-risk MG patients treated with cyclophosphamide in a retrospective single-clinic cohort. We suggest cyclophosphamide should be considered for rapid remission induction, corticosteroid reduction and long-term freedom from recurrent injectable therapies in selected patients, typically those with AChR antibodies.

Inter-alpha-trypsin inhibitor heavy chain H3 is a potential biomarker for disease activity in myasthenia gravis

Myasthenia gravis is a chronic antibody-mediated autoimmune disease disrupting neuromuscular synaptic transmission. Informative biomarkers remain an unmet need to stratify patients with active disease requiring intensified monitoring and therapy; their identification is the primary objective of this study. We applied mass spectrometry-based proteomic serum profiling for biomarker discovery. We studied an exploration and a prospective validation cohort consisting of 114 and 140 anti-acetylcholine receptor antibody (AChR-Ab)-positive myasthenia gravis patients, respectively. For downstream analysis, we applied a machine learning approach. Protein expression levels were confirmed by ELISA and compared to other myasthenic cohorts, in addition to myositis and neuropathy patients. Anti-AChR-Ab levels were determined by a radio receptor assay. Immunohistochemistry and immunofluorescence of intercostal muscle biopsies were employed for validation in addition to interactome studies of inter-alpha-trypsin inhibitor heavy chain H3 (ITIH3). Machine learning identified ITIH3 as potential serum biomarker reflective of disease activity. Serum levels correlated with disease activity scores in the exploration and validation cohort and were confirmed by ELISA. Lack of correlation between anti-AChR-Ab levels and clinical scores underlined the need for biomarkers. In a subgroup analysis, ITIH3 was indicative of treatment responses. Immunostaining of muscle specimens from these patients demonstrated ITIH3 localization at the neuromuscular endplates in myasthenia gravis but not in controls, thus providing a structural equivalent for our serological findings. Immunoprecipitation of ITIH3 and subsequent proteomics lead to identification of its interaction partners playing crucial roles in neuromuscular transmission. This study provides data on ITIH3 as a potential pathophysiological-relevant biomarker of disease activity in myasthenia gravis. Future studies are required to facilitate translation into clinical practice.

B cell-targeting chimeric antigen receptor T cells as an emerging therapy in neuroimmunological diseases

BACKGROUND

Neuroimmunology research and development has been marked by substantial advances, particularly in the treatment of neuroimmunological diseases, such as multiple sclerosis, myasthenia gravis, neuromyelitis optica spectrum disorders, and myelin oligodendrocyte glycoprotein antibody disease. With more than 20 drugs approved for multiple sclerosis alone, treatment has become more personalised. The approval of disease-modifying therapies, particularly those targeting B cells, has highlighted the role of immunotherapeutic interventions in the management of these diseases. Despite these successes, challenges remain, particularly for patients who do not respond to conventional therapies, underscoring the need for innovative approaches.

RECENT DEVELOPMENTS

The approval of monoclonal antibodies, such as ocrelizumab and ofatumumab, which target CD20, and inebilizumab, which targets CD19, for the treatment of various neuroimmunological diseases reflects progress in the understanding and management of B-cell activity. However, the limitations of these therapies in halting disease progression or activity in patients with multiple sclerosis or neuromyelitis optica spectrum disorders have prompted the exploration of cell-based therapies, particularly chimeric antigen receptor (CAR) T cells. Initially successful in the treatment of B cell-derived malignancies, CAR T cells offer a novel therapeutic mechanism by directly targeting and eliminating B cells, potentially overcoming the shortcomings of antibody-mediated B cell depletion. WHERE NEXT?: The use of CAR T cells in autoimmune diseases and B cell-driven neuroimmunological diseases shows promise as a targeted and durable option. CAR T cells act autonomously, penetrating deep tissue and effectively depleting B cells, especially in the CNS. Although the therapeutic potential of CAR T cells is substantial, their application faces hurdles such as complex logistics and management of therapy-associated toxic effects. Ongoing and upcoming clinical trials will be crucial in determining the safety, efficacy, and applicability of CAR T cells. As research progresses, CAR T cell therapy has the potential to transform treatment for patients with neuroimmunological diseases. It could offer extended periods of remission and a new standard in the management of autoimmune and neuroimmunological disorders.

Refocusing generalized myasthenia gravis: Patient burden, disease profiles, and the role of evolving therapy

BACKGROUND AND PURPOSE

Generalized myasthenia gravis (gMG) continues to present significant challenges for clinical management due to an unpredictable disease course, frequent disease fluctuations, and varying response to therapy. The recent availability of new pharmacologic therapies presents a valuable opportunity to reevaluate how this disease is classified, assessed, and managed and identify new ways to improve the clinical care of patients with gMG.

METHODS

Narrative review was made of publications identified via searches of PubMed and selected congresses (January 2000-September 2022).

RESULTS

New consensus definitions are required to ensure consistency, to better characterize patients, and to identify patients who will benefit from specific drugs and earlier use of these agents. There is a need for more frequent, standardized patient assessment to identify the cause of motor function deficits, provide a clearer picture of the disease burden and its impact on daily living and quality of life (QoL), and better support treatment decision-making. Novel approaches that target different components of the immune system will play a role in more precise treatment of patients with gMG, alongside the development of new algorithms to guide individualized patient management.

CONCLUSIONS

gMG has a physical, mental, and social impact, resulting in a considerable burden of disease and substantially decreased QoL, despite standard treatments. The availability of novel, targeted treatments that influence key pathological mediators of gMG, together with new biomarkers, offers the potential to optimize patient management and ultimately enables a greater number of patients to achieve minimal manifestation status and a reduced burden of disease.

Building, Breaking, and Repairing Neuromuscular Synapses

A coordinated and complex interplay of signals between motor neurons, skeletal muscle cells, and Schwann cells controls the formation and maintenance of neuromuscular synapses. Deficits in the signaling pathway for building synapses, caused by mutations in critical genes or autoantibodies against key proteins, are responsible for several neuromuscular diseases, which cause muscle weakness and fatigue. Here, we describe the role that four key genes, Agrin, Lrp4, MuSK, and Dok7, play in this signaling pathway, how an understanding of their mechanisms of action has led to an understanding of several neuromuscular diseases, and how this knowledge has contributed to emerging therapies for treating neuromuscular diseases.

Generalized myasthenia gravis with acetylcholine receptor antibodies: A guidance for treatment

BACKGROUND

Generalized myasthenia gravis (MG) with antibodies against the acetylcholine receptor is a chronic disease causing muscle weakness. Access to novel treatments warrants authoritative treatment recommendations. The Nordic countries have similar, comprehensive health systems, mandatory health registers, and extensive MG research.

METHODS

MG experts and patient representatives from the five Nordic countries formed a working group to prepare treatment guidance for MG based on a systematic literature search and consensus meetings.

RESULTS

Pyridostigmine represents the first-line symptomatic treatment, while ambenonium and beta adrenergic agonists are second-line options. Early thymectomy should be undertaken if a thymoma, and in non-thymoma patients up to the age of 50-65 years if not obtaining remission on symptomatic treatment. Most patients need immunosuppressive drug treatment. Combining corticosteroids at the lowest possible dose with azathioprine is recommended, rituximab being an alternative first-line option. Mycophenolate, methotrexate, and tacrolimus represent second-line immunosuppression. Plasma exchange and intravenous immunoglobulin are used for myasthenic crises and acute exacerbations. Novel complement inhibitors and FcRn blockers are effective and fast-acting treatments with promising safety profiles. Their use depends on local availability, refunding policies, and cost-benefit analyses. Adapted physical training is recommended. Planning of pregnancies with optimal treatment, information, and awareness of neonatal MG is necessary. Social support and adaptation of work and daily life activities are recommended.

CONCLUSIONS

Successful treatment of MG rests on timely combination of different interventions. Due to spontaneous disease fluctuations, comorbidities, and changes in life conditions, regular long-term specialized follow-up is needed. Most patients do reasonably well but there is room for further improvement. Novel treatments are promising, though subject to restricted access due to costs.

Efgartigimod in generalized myasthenia gravis: A real-life experience at a national reference center

BACKGROUND AND PURPOSE

Inhibition of the neonatal Fc receptor (FcRn) for IgG is a promising new therapeutic strategy for antibody-mediated disorders. We report our real-life experience with efgartigimod (EFG) in 19 patients with generalized myasthenia gravis (gMG) along a clinical follow-up of 14 months.

METHODS

EFG was administered according to the GENERATIVE protocol (consisting of a Fixed period of two treatment cycles [given 1 month apart] of four infusions at weekly intervals, followed by a Flexible period of re-cycling in case of worsening). Eight patients were positive for acetylcholine receptor antibody, four for muscle-specific tyrosine kinase antibody, and two for lipoprotein-related protein 4 antibody, and five were classified as triple negative. Efficacy of EFG was assessed by the Myasthenia Gravis Activities of Daily Living, Myasthenia Gravis Composite, and Quantitative Myasthenia Gravis scales.

RESULTS

Fifty-three percent of patients needed three treatment cycles, 26% needed four, and 21% needed five along the 14-month clinical follow-up. Meaningful improvement was observed at the end of each cycle with the clinical scores adopted. EFG had a dramatic effect on disease course, as during the year before treatment eight of 19 patients (42%) were hospitalized, and 15 of 19 (79%) needed treatment with plasma exchange or immunoglobulins; three of 19 (16%) were admitted to the intensive care unit. During EFG, none of the patients was hospitalized and only one patient required plasma exchange and intravenous immunoglobulins. No major side effects or infusion-related reactions occurred.

CONCLUSIONS

We observed that EFG was safe and modified significantly the course of the disease along a 14-month follow-up. Our experience strengthens the role of FcRn inhibition as an effective new tool for long-term treatment of gMG.

B cell lineage reconstitution underlies CAR-T cell therapeutic efficacy in patients with refractory myasthenia gravis

B-cell maturation antigen (BCMA), expressed in plasmablasts and plasma cells, could serve as a promising therapeutic target for autoimmune diseases. We reported here chimeric antigen receptor (CAR) T cells targeting BCMA in two patients with highly relapsed and refractory myasthenia gravis (one with AChR-IgG, and one with MuSk-IgG). Both patients exhibited favorable safety profiles and persistent clinical improvements over 18 months. Reconstitution of B-cell lineages with sustained reduced pathogenic autoantibodies might underlie the therapeutic efficacy. To identify the possible mechanisms underlying the therapeutic efficacy of CAR-T cells in these patients, longitudinal single-cell RNA and TCR sequencing was conducted on serial blood samples post infusion as well as their matching infusion products. By tracking the temporal evolution of CAR-T phenotypes, we demonstrated that proliferating cytotoxic-like CD8 clones were the main effectors in autoimmunity, whereas compromised cytotoxic and proliferation signature and profound mitochondrial dysfunction in CD8+ Te cells before infusion and subsequently defect CAR-T cells after manufacture might explain their characteristics in these patients. Our findings may guide future studies to improve CAR T-cell immunotherapy in autoimmune diseases.

Integrative multi-omics analysis identifies genetically supported druggable targets and immune cell specificity for myasthenia gravis

BACKGROUND

Myasthenia gravis (MG) is a chronic autoimmune disorder characterized by fluctuating muscle weakness. Despite the availability of established therapies, the management of MG symptoms remains suboptimal, partially attributed to lack of efficacy or intolerable side-effects. Therefore, new effective drugs are warranted for treatment of MG.

METHODS

By employing an analytical framework that combines Mendelian randomization (MR) and colocalization analysis, we estimate the causal effects of blood druggable expression quantitative trait loci (eQTLs) and protein quantitative trait loci (pQTLs) on the susceptibility of MG. We subsequently investigated whether potential genetic effects exhibit cell-type specificity by utilizing genetic colocalization analysis to assess the interplay between immune-cell-specific eQTLs and MG risk.

RESULTS

We identified significant MR results for four genes (CDC42BPB, CD226, PRSS36, and TNFSF12) using cis-eQTL genetic instruments and three proteins (CTSH, PRSS8, and CPN2) using cis-pQTL genetic instruments. Six of these loci demonstrated evidence of colocalization with MG susceptibility (posterior probability > 0.80). We next undertook genetic colocalization to investigate cell-type-specific effects at these loci. Notably, we identified robust evidence of colocalization, with a posterior probability of 0.854, linking CTSH expression in TH2 cells and MG risk.

CONCLUSIONS

This study provides crucial insights into the genetic and molecular factors associated with MG susceptibility, singling out CTSH as a potential candidate for in-depth investigation and clinical consideration. It additionally sheds light on the immune-cell regulatory mechanisms related to the disease. However, further research is imperative to validate these targets and evaluate their feasibility for drug development.

Registered trials on novel therapies for myasthenia gravis: a cross-sectional study on ClinicalTrials.gov

Novel biologics in MG therapy research is on the rise. This research aimed to investigate the characteristics of registered trials on novel therapies for myasthenia gravis on ClinicalTrials.gov. This cross-sectional study used a descriptive approach to assess the features of the included trials on ClinicalTrials.gov. We found 62 registered trials from 2007 to 2023 on ClinicalTrials.gov. The results showed a yearly rise in the number of registered trials (r = 0.76, p < 0.001). Following 2017, more industry-sponsored trials were conducted (91.5% [43] vs. 60% [9], p = 0.009), fewer results were released (10.6% [5] vs. 60% [9], p = 0.001), and more trials entered phase 3 (67.4% [31] vs. 20% [2], p = 0.001). The most researched novel medications were neonatal Fc receptor inhibitors (51.2% [21]), complement inhibitors (39.0% [16]), and B cell depletors (14.6% [6]). According to the website's data, the neonatal Fc receptor inhibitors and complement inhibitors were effective in treating myasthenia gravis patients in three trials (NCT03315130, NCT03669588, and NCT00727194). This study provides valuable insights into the profile of registered trials on novel therapies for myasthenia gravis. More clinical studies are needed in the future to prove the value of its application.

Myasthenia gravis-Pathophysiology, diagnosis, and treatment

Myasthenia gravis (MG) is an autoimmune disease characterized by dysfunction of the neuromuscular junction resulting in skeletal muscle weakness. It is equally prevalent in males and females, but debuts at a younger age in females and at an older age in males. Ptosis, diplopia, facial bulbar weakness, and limb weakness are the most common symptoms. MG can be classified based on the presence of serum autoantibodies. Acetylcholine receptor (AChR) antibodies are found in 80%-85% of patients, muscle-specific kinase (MuSK) antibodies in 5%-8%, and <1% may have low-density lipoprotein receptor-related protein 4 (Lrp4) antibodies. Approximately 10% of patients are seronegative for antibodies binding the known disease-related antigens. In patients with AChR MG, 10%-20% have a thymoma, which is usually detected at the onset of the disease. Important differences between clinical presentation, treatment responsiveness, and disease mechanisms have been observed between these different serologic MG classes. Besides the typical clinical features and serologic testing, the diagnosis can be established with additional tests, including repetitive nerve stimulation, single fiber EMG, and the ice pack test. Treatment options for MG consist of symptomatic treatment (such as pyridostigmine), immunosuppressive treatment, or thymectomy. Despite the treatment with symptomatic drugs, steroid-sparing immunosuppressants, intravenous immunoglobulins, plasmapheresis, and thymectomy, a large proportion of patients remain chronically dependent on corticosteroids (CS). In the past decade, the number of treatment options for MG has considerably increased. Advances in the understanding of the pathophysiology have led to new treatment options targeting B or T cells, the complement cascade, the neonatal Fc receptor or cytokines. In the future, these new treatments are likely to reduce the chronic use of CS, diminish side effects, and decrease the number of patients with refractory disease.

Lambert-Eaton myasthenic syndrome

Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune disease characterized by proximal muscle weakness, loss of tendon reflexes, and autonomic dysfunction. Muscle weakness usually starts in the upper legs and can progress to oculobulbar and in severe cases respiratory muscles. P/Q-type voltage-gated calcium channels (VGCCs) localized in the presynaptic motor nerve terminal and in the autonomic nervous system are targeted by antibodies in LEMS patients. These antibodies can be detected in about 90% of patients, and the presence of decrement and increment upon repetitive nerve stimulation is also a highly sensitive diagnostic test. Rapid diagnosis is important because of the association with SCLC in 50%-60% of patients, which stresses the need for vigorous tumor screening after diagnosis. Clinical parameters can predict tumor probability and guide frequency of tumor screening. Treatment of the tumor as well as symptomatic treatment and immunosuppression can effectively control symptoms in the majority of patients.

Paraneoplastic Neurologic Syndromes

OBJECTIVE

Progress is ongoing in understanding paraneoplastic neurologic disorders, with new syndromes and antibodies being described and more detailed evidence available to guide workup for diagnosis and treatment to improve outcomes. Many excellent reviews have summarized the molecular features of different antibodies, but this article emphasizes the clinical features of each syndrome that may help guide initial diagnosis and treatment, which often should occur before an antibody or cancer is found to confirm the diagnosis.

LATEST DEVELOPMENTS

Recent findings include updated diagnostic criteria with validated sensitivity and specificity, discovery of novel antibodies, and clinical findings that increase the likelihood of an underlying paraneoplastic disorder. Suggestive syndromes that have been recently identified include faciobrachial dystonic seizures and pilomotor auras in anti-leucine-rich glioma inactivated protein 1 encephalitis, extreme delta brush on EEG in N-methyl-d-aspartate (NMDA)-receptor encephalitis, déjà vu aura in anti-glutamic acid decarboxylase 65 (GAD65) encephalitis, and sleep disturbances in several disorders. In addition, there is confirmed utility of brain positron emission tomography (PET) and CSF markers, including carcinoembryonic antigen and oligoclonal bands, as well as improved tests for the presence of leptomeningeal cancer cells in CSF. Associations of cancer immunotherapies with paraneoplastic syndromes and herpes simplex virus encephalitis (and COVID-19) with NMDA-receptor encephalitis have been described.

ESSENTIAL POINTS

All neurologists should be aware of advances regarding paraneoplastic neurologic syndromes, as patients can present with a wide variety of neurologic symptoms and earlier diagnosis and treatment can improve outcomes.

Impact of Ravulizumab on Patient Outcomes and Quality of Life in Generalized Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune ion channel disorder in which antibodies to different end-plate antigens impair neuromuscular transmission, ultimately leading to muscle weakness and fatigability. In about 85% of patients with MG, autoantibodies against the acetylcholine receptor (AChR) activate the complement cascade, causing damage to the neuromuscular junction. MG is a chronic disorder for which standard therapies with corticosteroids, immunosuppressive drugs, and immunomodulation with plasma exchange or intravenous immunoglobulins modify the course of the disease, but the residual burden of physical, psychological, and social disability highlights several unmet needs, among these the need for specific, targeted, and well tolerated therapies able to improve the patients' quality of life. Complement inhibition paved the way to precision medicine in MG since, for the first time, a specific therapy targeting a crucial pathogenetic step has been designed, tested, and proven to be effective in a controlled fashion. Ravulizumab represents the first long-acting complement inhibitor approved for treatment of patients with generalized MG, able to provide rapid, complete, and sustained complement inhibition. Ravulizumab improved the MG Activity of Daily Living scale and other clinical parameters up to 26 weeks as shown by the CHAMPION MG trial, and by its open label extension, with the added value of being administered every 8 weeks. The schedule of administration is likely to improve patients' adherence and hence their quality of life. The introduction of complement inhibition will considerably change the traditional therapeutic strategy for MG.

Galactosylation of serum immunoglobulin G in myasthenia gravis with different autoantibodies

Myasthenia gravis (MG) is a disease with impaired transmission at the neuromuscular junction, characterised by weakness and fatigability of skeletal muscles. In acquired autoimmune MG, antibodies against acetylcholine receptor (AChRAb) or muscle-specific tyrosine kinase (MuSKAb) are present. There is not much data about immunoglobulin G (IgG) galactosylation in MG, and none based on interactions with lectins. This study aims to examine IgG galactosylation in two types of myasthenia, using affinity immunoelectrophoresis with lectin concanavalin A (Con A). Affinity of Con A-IgG interaction, expressed as retardation coefficient (R), indicated the presence of degalactosylated IgG. The average R values were significantly different between three examined groups, being the lowest in controls (healthy subjects), higher in acetylcholine receptor (AChR) MG, and the highest in muscle-specific tyrosine kinase (MuSK) MG (ANOVA, p < .05). This indicated decreased galactosylation of IgG in both types of MG compared to controls, more pronounced in MuSK MG. IgG galactosylation was also investigated in relation to the disease severity score, determined according to the Myasthenia Gravis Foundation of America (MGFA) criteria, at the time of diagnosis, nadir of the disease and last check-out visit. The average R values for mild disease (stages I-IIIa) were significantly lower than for severe disease (stages IIIb-V), both at the time of diagnosis (p < .05), and at the nadir of the disease (p < .05). Thus, IgG galactosylation was associated with the presence of specific autoantibodies in MG, as well as with disease severity for both types of MG, and may be a predictive marker of MG outcome.

Therapeutic and prognostic features in myasthenia gravis patients followed in a tertiary neuromuscular diseases center in Turkey

Introduction

In this study, we aim to evaluate the treatment responses and prognostic characteristics of Myasthenia Gravis (MG) patients followed in a tertiary neuromuscular diseases center in Turkey.

Methods

One hundred seventy four MG patients (between years 2011 and 2022) in Antalya, Turkey were diagnosed, and evaluated on a classification of MG was based on Myasthenia. Gravis Foundation of America (MGFA) clinical classification. Exclusion of other possible diseases in the differential diagnosis and support by beneficial response to treatment with acetylcholinesterase inhibitors were also taken into consideration.

Results

Mean age of participants was 54.86 (SD = 14.856; min-max = 22-84). Ninety (51.7%) were female. MG was more common in women under the age of 65 (58%) and in men over the age of 65 (64%). Generalized MG was seen in 75.3% of the patients. Anti-AChR positivities were detected in 52.3%, Anti-MuSK positivity in 4.6%, and seronegativity in 22.4%. Thymoma was detected in nearly 9.8% and thymectomy was performed in 28.7 percent. Most of the patients (57.5%) were using corticosteroids. Azathioprine was used by 39% and mycophenolate mofetil by 10.3% of patients. Mortality was higher and disease was more severe in late-onset (>50 years) MG patients (especially in the COVID-19 pandemic). Eight patients (four women, four men, mean age 75.5 years) died during follow-up. None of them died due to myasthenic worsening, two died due to malignancy and two due to infection. During the COVID pandemic, 16 patients (9.2%) had COVID infection. Four patients died due to COVID-19 infection, these four patients had serious comorbidities, and three of them were elderly (>75 years).

Conclusion

In conclusion, MG is more common in women between the ages of 20-40 and in men over the age of 65. The use of corticosteroids was more common under the age of 50, and the use of non-steroidal immunosuppressant agents was more common over the age of 50. Thymectomy is still an important supportive treatment approach in anti-AChR positive and seronegative generalized patients under 50 years of age. IVIG and plasmapheresis are effective treatments during acute exacerbations and bridging periods of treatments. Specific treatments are needed especially for resistant group of patients.

The impact of thymectomy in subgroups of Myasthenia gravis patients: a single center longitudinal observation

BACKGROUND

Myasthenia gravis (MG) is a rare neuromuscular disorder. Symptoms can range from ptosis only to life threatening myasthenic crisis. Thymectomy is recommended for anti-acetylcholine receptor-antibody positive patients with early-onset MG. Here, we investigated prognostic factors shaping therapeutic outcomes of thymectomy to improve patient stratification.

METHODS

We retrospectively collected single-center data from a specialized center for MG from all consecutive adult patients that underwent thymectomy from 01/2012 to 12/2020. We selected patients with thymoma-associated and non-thymomatous MG for further investigations. We analyzed the patient collective regarding perioperative parameters in relation to the surgical approach. Furthermore, we investigated the dynamics of the anti-acetylcholine receptor-antibody titers and concurrent immunosuppressive therapies, as well as the therapeutic outcomes in dependence of clinical classifications.

RESULTS

Of 137 patients 94 were included for further analysis. We used a minimally invasive approach in 73 patients, whereas 21 patients underwent sternotomy. A total of 45 patients were classified as early-onset MG (EOMG), 28 as late-onset MG (LOMG) and 21 as thymoma-associated MG (TAMG). The groups differed in terms of age at diagnosis (EOMG: 31.1 ± 12.2 years; LOMG: 59.8 ± 13.7 years; TAMG: 58.6 ± 16.7 years; p < 0.001). Patients with EOMG and TAMG were more often female than patients in the LOMG group (EOMG: 75.6%; LOMG: 42.9%; TAMG: 61.9%; p = 0.018). There were no significant differences in outcome scores (quantitative MG; MG activities of daily living; MG Quality of Live) with a median follow-up of 46 months. However, Complete Stable Remission was achieved significantly more frequently in the EOMG group than in the other two groups (p = 0.031). At the same time, symptoms seem to improve similarly in all three groups (p = 0.25).

CONCLUSION

Our study confirms the benefit of thymectomy in the therapy of MG. Both, the concentration of acetylcholine receptor antibodies and the necessary dosage of cortisone therapy show a continuous regression after thymectomy in the overall cohort. Beyond EOMG, groups of LOMG and thymomatous MG responded to thymectomy as well, but therapy success was less pronounced and delayed compared to the EOMG subgroup. Thymectomy is a mainstay of MG therapy to be considered in all subgroups of MG patients investigated.

Ravulizumab: A Review in Generalised Myasthenia Gravis

Ravulizumab (ULTOMIRIS^®) is the first long-acting complement C5 inhibitor (administered intravenously every 8 weeks) to be approved in several countries globally, for adults with generalised myasthenia gravis (gMG) who are anti-acetylcholine receptor antibody-positive (AChR Ab+). In the phase III CHAMPION MG trial, intravenous ravulizumab was associated with statistically significant improvements in the MG-Activities of Daily Living scale at week 26 of treatment compared with placebo in adults with AChR Ab+ gMG. Improvements in the Quantitative MG scale total score were also statistically significantly higher in ravulizumab than placebo recipients. These improvements were sustained to week 26 of treatment. Ravulizumab was generally well tolerated; the most common treatment-emergent adverse events were headache, diarrhoea and nausea. Efficacy and tolerability data for up to 1 year from the ongoing open-label extension phase are consistent with those from the randomized, placebo-controlled phase; further results are awaited with interest. Thus, ravulizumab is an efficacious, generally well tolerated and convenient treatment option in adults with AChR Ab+ gMG, expanding the options available for gMG management.

Epidemiology and treatment of myasthenia gravis: a retrospective study using a large insurance claims dataset in Germany

Myasthenia gravis (MG) is a rare, chronic autoimmune disease with symptoms of fluctuating muscular weakness and fatigability. The aim of this retrospective cohort study was to estimate the prevalence and incidence of MG in Germany, and to understand the burden of disease and treatment patterns, based on anonymized German claims data. Two patient samples were identified: (1) incident MG patients with newly onset disease between 2015 and 2019, and (2) prevalent MG patients in 2019. In total, 775 incident MG patients with a mean age of 66.9 years; and 1,247 prevalent MG patients with a mean age of 68.6 years were included. The prevalence for Germany was estimated to be 39.3/100,000 on 31/12/2019; the incidence in 2019 was 4.6 cases/100,000 persons. The 12-month mortality was 5.7. For 31.5% of the incident patients, no MG treatment was observed in the first year after the index date. Of all incident patients, 29.9% experienced an exacerbation, and 6.7% a myasthenic crisis during the observation. Our study indicates that a substantial proportion of MG patients remains untreated. Many MG patients still experience exacerbations / MG crises. MG seems to be associated with an excess mortality in comparison to the general non-MG population.

Short-term outcome prediction for myasthenia gravis: an explainable machine learning model

Background

Myasthenia gravis (MG) is an autoimmune disease characterized by muscle weakness and fatigability. The fluctuating nature of the disease course impedes the clinical management.

Objective

The purpose of the study was to establish and validate a machine learning (ML)-based model for predicting the short-term clinical outcome in MG patients with different antibody types.

Methods

We studied 890 MG patients who had regular follow-ups at 11 tertiary centers in China from 1 January 2015 to 31 July 2021 (653 patients for derivation and 237 for validation). The short-term outcome was the modified post-intervention status (PIS) at a 6-month visit. A two-step variable screening was used to determine the factors for model construction and 14 ML algorithms were used for model optimisation.

Results

The derivation cohort included 653 patients from Huashan hospital [age 44.24 (17.22) years, female 57.6%, generalized MG 73.5%], and the validation cohort included 237 patients from 10 independent centers [age 44.24 (17.22) years, female 55.0%, generalized MG 81.2%]. The ML model identified patients who were improved with an area under the receiver operating characteristic curve (AUC) of 0.91 [0.89-0.93], 'Unchanged' 0.89 [0.87-0.91], and 'Worse' 0.89 [0.85-0.92] in the derivation cohort, whereas identified patients who were improved with an AUC of 0.84 [0.79-0.89], 'Unchanged' 0.74 [0.67-0.82], and 'Worse' 0.79 [0.70-0.88] in the validation cohort. Both datasets presented a good calibration ability by fitting the expectation slopes. The model is finally explained by 25 simple predictors and transferred to a feasible web tool for an initial assessment.

Conclusion

The explainable, ML-based predictive model can aid in forecasting the short-term outcome for MG with good accuracy in clinical practice.

Diagnosing myasthenia gravis using orthoptic measurements: assessing extraocular muscle fatiguability

INTRODUCTION

Diagnosing ocular myasthenia gravis (MG) can be challenging because serum antibodies are often not detected. We aimed to explore whether determining extraocular muscle (EOM) weakness using orthoptic measures, including an adapted Hess chart examination, can aid in diagnosing MG.

METHODS

We conducted a prospective study among patients with acetylcholine receptor antibody positive MG (20 recently diagnosed, 19 chronic) and 14 seronegative MG patients. We compared orthoptic measures to 19 healthy and 18 disease controls with Graves orbitopathy, chronic progressive external ophthalmoplegia or oculopharyngeal muscular dystrophy. Maximal eye duction angles were measured using a synoptophore. Gaze deviations between eyes were measured using standard Hess chart examination with addition of 1 min persistent gaze to assess MG-associated fatiguability. Receiver operating characteristics curve analysis was performed.

RESULTS

For duction angles, the area under the curve (AUC) was 0.73 comparing MG to healthy, and 0.69 comparing to patient controls. For the outer field of the Hess chart, the AUC was 0.89 comparing to healthy and 0.54 to patient controls. For drift, the AUC was 0.93 comparing to healthy and 0.93 to patient controls. The sensitivity and specificity of the presence of drift was 81% and 100%.

DISCUSSION

Orthoptic measurements can be used to diagnose MG by quantifying EOM weakness and fatiguability. Drift during persistent gaze on a Hess chart is specific for MG and could be used for diagnostic purposes. The Hess chart examination is widely available, inexpensive and fast. Moreover, orthoptic measurements may be a clinically relevant outcome measure for clinical trials.

Current management of myasthenia gravis in Belgium: a single-center experience

INTRODUCTION

As new treatments are becoming available for patients with myasthenia gravis (MG), it is worth reflecting on the actual status of MG treatment to determine which patients would most likely benefit from the new treatments.

METHODS

We reviewed the clinical files of all MG patients seen at the Department of Neurology of the Antwerp University Hospital during the years 2019, 2020 and 2021.

RESULTS

163 patients were included. Age at diagnosis varied from the first to the eighth decades, with a peak of incidence from 60 to 70 years for both genders, and an additional peak from 20 to 30 years in women. Diplopia and ptosis were by far the most common onset symptom. At maximum disease severity, 24% of the patients still had purely ocular symptoms and 4% needed mechanical ventilation. 97% of the patients received a treatment with pyridostigmine and 68% with corticosteroids, often in combination with immunosuppressants. More than half reported side effects. At the latest visit, 50% of the patients were symptom-free. Also, half of the symptomatic patients were fulltime at work or retired with no or mild limitations in daily living. The remaining patients were working part-time, on sick leave, or retired with severe limitations.

DISCUSSION AND CONCLUSION

The majority of MG patients are doing well with currently available treatments, but often at the cost of side effects in the short and in the long term. A significant group is in need of better treatments.

The best and worst of times in therapy development for myasthenia gravis

Within the last 5 years, the US Food and Drug Administration (FDA) has approved complement and neonatal Fc receptor (FcRN) inhibitors for treatment of generalized myasthenia gravis, and several other therapies are in late-stage clinical trials or under regulatory review. However, questions about which patients are most likely to benefit from which therapies, and the relative effectiveness of these very expensive drugs, has resulted in uncertainty around the place that they should occupy in the existing therapeutic armamentarium. MGNet (a Rare Diseases Clinical Research Consortium funded by the National Institute of Neurological Diseases and Stroke) held two meetings during the 14th International Conference of the Myasthenia Gravis Foundation of America to discuss the most critical needs for clinical trial readiness and biomarker development in the context of therapy development for myasthenia gravis. Herein we provide a summary of these discussions, but not a consensus opinion, and offer a series of recommendations to guide focused research in the most critical areas. We welcome ongoing discussion through comments on this work.

Pneumonia in myasthenia gravis: Microbial etiology and clinical management

Introduction

Patients with myasthenia gravis (MG) are prone to the development of pneumonia due to the long-term immunotherapies they receive and a tendency for aspiration. Pneumonia remains a risk factor for MG worsening and is the most prevalent cause of mortality in MG patients. Classification of the pathogens involved and exploration of the risk factors for mechanical ventilation (MV) could aid in improving clinical outcomes.

Methods

Between January 2013 and October 2022, we performed an inpatient database review for MG patients with pneumonia concurrence in a tertiary research center specializing in neuromuscular disorders. The clinical and microbiological characteristics of 116 MG patients with pneumonia were retrospectively analyzed.

Results

In our cohort, 90.32% (112/124) of organisms were bacteria and 42.86% (48/112) of pathogenic bacteria were carbapenem-resistant. A high abundance of Epstein-Barr virus (EBV) was detected using next-generation sequencing (NGS) in 12 patients, while cytomegalovirus (CMV) was detected in 8 patients. Non-fermentative Gram-negative bacilli were the most prevalent microorganisms, in which ampicillin, sulfamethoxazole-trimethoprim (SMZ-TMP), piperacillin, cefoperazone, ceftazidime, and cefepime may have an anti-infectious effect. Moreover, peripheral lymphocyte percentage [odds ratio (OR) 0.88, 95% CI 0.75-0.96, p = 0.02] and serum globulin (OR 1.16, 95% CI 1.02-1.35, p = 0.03) were significantly associated with the risk of MV demand.

Discussion

Our identification of the microbial etiology of pneumonia in MG patients may provide future perspectives on accurate antibiotic options and enable early interventions when risk factors are present.

Myasthenia gravis - a retrospective analysis of e-mail inquiries made to a patient organisation and specialized center to uncover unmet needs from patients and caregivers

BACKGROUND AND AIMS

Myasthenia Gravis requires expert treatment from specialized neurologists. In Germany, this treatment is mainly provided by 18 Integrated Myasthenia Centers (iMZ) accredited by the German Myasthenia Gravis Association (DMG). The DMG is a large and well-organized patient organisation that is regarded as a trusted source for disease-specific information. The aim of this study was to analyse the type of requests that each of these institutions receives in order to identify any potential unmet needs regarding the availability of advice for patients and caregivers. This data can then be used in further research to tailor modern digital communication tools to the specific needs of MG patients.

METHODS

Counselling requests sent via e-mail to both institutions were extracted for defined examination periods and divided into a period 'before COVID-19 pandemic' (01.07.2019-31.12.2019) and 'during COVID-19 pandemic' (01.07.2020-31.12.2020). Requests were then analysed using four main categories: medical requests, organisational issues, COVID-19 and social legislation inquiries.

RESULTS

One thousand seven hundred eleven requests for advice were addressed to DMG and iMZ Charité. Most inquiries directed to the DMG (47%; n = 750) were related to medical issues, most frequently to side effects of medications (n = 325; 20%) and questions about treatment (n = 263; 16%), followed by inquiries regarding organisational issues (26%; n = 412). About half of the inquiries (n = 69; 58%) to the iMZ Charité were related to medical issues and almost one in three inquiries concerned organisational issues (n = 37; 30%). About one in ten inquiries concerned socio-legal matters (iMZ: n = 7; 6% and DMG: n = 177; 11%). During the pandemic, COVID-19 related issues accounted for 8% (n = 6) of inquiries at iMZ, and 16% (n = 253) at DMG.

CONCLUSIONS

MG sufferers have a high demand for timely advice. In the current setting, they address their requests to both iMZs and the DMG via e-mail. Our findings confirm that the DMG is highly trusted by patients and caregivers and is used to obtain second opinions. A relevant proportion of requests to the iMZ could be answered more effectively through standardized responses or improved process management. The implementation of modern digital solutions, including telemedicine, for communication between patient and specialist should be evaluated in further research.

Efficacy and Safety of Rituximab for New-Onset Generalized Myasthenia Gravis: The RINOMAX Randomized Clinical Trial

Importance

Rituximab is a third-line option for refractory generalized myasthenia gravis (MG) based on empirical evidence, but its effect in new-onset disease is unknown.

Objective

To investigate the efficacy and safety of rituximab compared with placebo as an add-on to standard of care for MG.

Design, Setting, and Participants

This randomized, double-blind, placebo-controlled study took place throughout 48 weeks at 7 regional clinics in Sweden. Key inclusion criteria were age older than 18 years, onset of generalized symptoms within 12 months or less, and a Quantitative Myasthenia Gravis (QMG) score of 6 or more. Patients were screened from October 20, 2016, to March 2, 2020. Key exclusion criteria included pure ocular MG, suspected thymoma, previous thymectomy, and prior noncorticosteroid immunosuppressants or high doses of corticosteroids.

Interventions

Participants were randomized 1:1 without stratification to a single intravenous infusion of 500 mg of rituximab or matching placebo.

Main Outcomes and Measures

Minimal disease manifestations at 16 weeks defined as a QMG score of 4 or less with prednisolone, 10 mg or less daily, and no rescue treatment.

Results

Of 87 potentially eligible patients, 25 were randomized to rituximab (mean [SD] age, 67.4 [13.4] years; 7 [28%] female) and 22 to placebo (mean [SD] age, 58 [18.6] years; 7 [32%] female). Compared with placebo, a greater proportion with rituximab met the primary end point; 71% (17 of 24) in the rituximab group vs 29% (6 of 21) in the placebo group (Fisher exact test P = .007; probability ratio, 2.48 [95% CI, 1.20-5.11]). Secondary end points, comparing changes in Myasthenia Gravis Activities of Daily Living and Myasthenia Gravis Quality of Life at 16 weeks with QMG at 24 weeks did not differ between groups with censoring for rescue treatment (per-protocol analysis) but were in favor of active treatment when rescue treatment was taken into account by worst rank imputation (post hoc analysis). Rescue treatments were also more frequent in the placebo arm (rituximab: 1 [4%]; placebo, 8 [36%]). One patient in the placebo arm had a myocardial infarction with cardiac arrest and 1 patient in the active arm experienced a fatal cardiac event.

Conclusions and Relevance

A single dose of 500 mg of rituximab was associated with greater probability of minimal MG manifestations and reduced need of rescue medications compared with placebo. Further studies are needed to address long-term benefit-risk balance with this treatment.

Trial Registration

ClinicalTrials.gov Identifier: NCT02950155.

The effectiveness and side effects of pyridostigmine in the treatment of myasthenia gravis: a cross-sectional study

Pyridostigmine is the most commonly used drug in the symptomatic treatment of myasthenia gravis (MG); however, research into its effectiveness and side effects is scarce. The aim of this study was to assess the effectiveness, prevalence of side effects and net benefit of pyridostigmine. All MG patients participating in the Dutch-Belgian myasthenia patient registry were included. A dynamic online questionnaire was developed to assess the effectiveness, side effects and net benefit of pyridostigmine. Out of 642 invited patients, 410 patients (64%) fully completed the questionnaire; 61% reported that they currently used pyridostigmine, 36% had discontinued pyridostigmine and 2% reported to never have used pyridostigmine. Patients reported a median effectiveness of 60, IQR 28-78 and net benefit of 65, IQR 45-84. Of all patients currently using pyridostigmine, 91% reported side effects (vs. 55% in the control group). Most frequently reported side effects were flatulence, urinary urgency, muscle cramps, blurred vision and hyperhidrosis. In the group of patients who discontinued pyridostigmine, side effects were the reason for discontinuation in 26%. Diarrhea, abdominal cramps and muscle twitching were the most frequently cited reasons to discontinue pyridostigmine. These results can be used to guide shared decision making prior to starting symptomatic treatment for MG.

Safety of mRNA COVID ‐19 vaccines in patients with well controlled myasthenia gravis

Introduction/Aims

Data on safety and tolerability of the vaccines against severe acute respiratory virus coronavirus‐2 (SARS‐CoV‐2, or coronavirus disease‐2019 [COVID‐19]) in patients with myasthenia gravis (MG) are currently limited. In this study we investigated the safety of mRNA‐based two‐dose vaccination in a cohort of patients with MG.

Methods

This investigation was a prospective observational study of messenger RNA (mRNA)‐based vaccines administered to patients with MG with stable disease. Local and systemic reactogenicity after injection was monitored for each dose administered. The patients were categorized and clinically assessed following the recommendations of the Myasthenia Gravis Foundation of America.

Results

Thirty‐six males and 55 females (mean age at first vaccine dose, 58.8 years; standard deviation, = 17.1 years) received vaccines. Seventy‐two patients (79.1%) were taking one or more immunosuppressant(s). The most frequent adverse effects were injection‐site pain, fatigue, myalgia, chills, fever, and headache. Local and systemic reactions were transient; 58.2% of the patients developed one or more reaction(s). There were no anaphylactic reactions. None of the patients had a myasthenic crisis, and two developed a mild deterioration compared with their Quantitative Myasthenia Gravis baseline score. The clinical outcome scores showed no exacerbation of MG symptoms. Patients over 65 years of age developed fewer adverse effects. COVID‐19 vaccination did not induce clinical exacerbation in stable patients with MG, regardless of their age, sex, history of myasthenic crisis, or whether they were taking immunosuppressants.

Discussion

Our data are consistent with the mRNA COVID‐19 vaccine being well tolerated in patients with well‐controlled MG. The findings may contribute to decisions in vaccination campaigns in the future.

Total Plasma Exchange in Neuromuscular Junction Disorders—A Single-Center, Retrospective Analysis of the Efficacy, Safety and Potential Diagnostic Properties in Doubtful Diagnosis

Neuromuscular junction disorders (NJDs) are a heterogeneous group of diseases including myasthenia gravis (MG). In some cases, patients are present with myasthenic symptoms without evidence of autoimmune antibodies, making diagnosis challenging. Total plasma exchange (TPE) has proven efficacy in NJDs. The objective is to describe the safety and efficacy of TPE in NJD patients with questionable disease activity or uncertain diagnosis in order to assess the diagnostic potential of TPE. We report an observational, retrospective cohort study of clinical routine data. All the data were derived from the electronic medical records of the Department of Neurology at University Hospital Essen. We searched for patients with NJDs between 1 July 2018 and 30 June 2021. Of the 303 patients who presented to the department with NJDs, 20 were treated with TPE; 9 patients did not show a measurable benefit from TPE (45%), 6 of whom were diagnosed with seronegative MG. Of these, 3 (50%) had long-standing ocular symptoms. There were decreases in the mean arterial pressure, hemoglobin, hematocrit and fibrinogen during treatment, which were not considered clinically relevant. In (seronegative) myasthenic patients, TPE may help to verify an uncertain diagnosis or to reveal possible muscle damage, allowing unnecessary therapy to be avoided.

Criteria for Treatment Response in Myasthenia Gravis: Comparison Between Absolute Change and Improvement Percentage in Severity Scores

Background

The absolute change in the severity score between the baseline and pre-specified time frame (absolute criterion) was recommended as a criterion for myasthenia gravis (MG) treatment response. But heterogeneity of disease severity might dilute major changes in individual patients. The rationality of relative criterion (improvement percentage) had not been evaluated in treatment response in patients with MG.

Objectives

To investigate the consistency between an absolute criterion and a relative criterion in the evaluation of treatment response in patients with MG.

Methods

We retrospectively analyzed the treatment response to a 3-month standardized treatment protocol with only glucocorticoid in 257 MG patients native to immunological treatments. With the commonly used absolute criterion, cut-offs of relative criteria were generated with the receiver operating characteristic (ROC) curve in the whole cohort and in patients with different degrees of baseline severity stratified by pre-treatment quantitative myasthenia gravis score (QMGS). The consistency between absolute and relative criteria was examined with Cohen's Kappa test and Venn diagrams.

Results

The absolute and relative criteria had an overall substantial consistency (Kappa value, 0.639, p < 0.001) in the cohort. The Kappa values were substantial to almost perfect in mild and moderate groups and moderate in severe groups between the absolute and relative criteria (all p ≤ 0.001). More patients were classified as responsive with an absolute criterion while as unresponsive with a relative criterion in the moderate and severe groups.

Conclusions

The overall consistency between absolute and relative criteria was substantial in the whole cohort. The inconsistency between the two criteria was mainly from the moderate or severe patients at the baseline.

Corticosteroid Treatment-Resistance in Myasthenia Gravis

Chronic, high-dose, oral prednisone has been the mainstay of myasthenia gravis treatment for decades and has proven to be highly beneficial in many, toxic in some way to all, and not effective in a significant minority. No patient characteristics or biomarkers are predictive of treatment response leading to many patients suffering adverse effects with no benefit. Presently, measurements of treatment response, whether taken from clinician or patient perspective, are appreciated to be limited by lack of good correlation, which then complicates correlation to biological measures. Treatment response may be limited because disease mechanisms are not influenced by corticosteroids, limits on dosage because of adverse effects, or individual differences in corticosteroids. This review evaluates potential mechanisms that underlie lack of response to glucocorticoids in patients with myasthenia gravis.