Recommendations for myasthenia gravis clinical trials

Circulating miRNAs as Potential Biomarkers in Myasthenia Gravis: Tools for Personalized Medicine

Myasthenia gravis (MG) is an autoimmune disease caused by antibodies which attack receptors at the neuromuscular junction. One of the main difficulties in predicting the clinical course of MG is the heterogeneity of the disease, where disease progression differs greatly depending on the subgroup that the patient is classified into. MG subgroups are classified according to: age of onset [early-onset MG (EOMG; onset ≤ 50 years) versus late-onset MG (LOMG; onset > 50 years]; the presence of a thymoma (thymoma-associated MG); antibody subtype [acetylcholine receptor antibody seropositive (AChR+) and muscle-specific tyrosine kinase antibody seropositive (MuSK+)]; as well as clinical subtypes (ocular versus generalized MG). The diagnostic tests for MG, such as antibody titers, neurophysiological tests, and objective clinical fatigue score, do not necessarily reflect disease progression. Hence, there is a great need for reliable objective biomarkers in MG to follow the disease course as well as the individualized response to therapy toward personalized medicine. In this regard, circulating microRNAs (miRNAs) have emerged as promising potential biomarkers due to their accessibility in body fluids and unique profiles in different diseases, including autoimmune disorders. Several studies on circulating miRNAs in MG subtypes have revealed specific miRNA profiles in patients’ sera. In generalized AChR+ EOMG, miR-150-5p and miR-21-5p are the most elevated miRNAs, with lower levels observed upon treatment with immunosuppression and thymectomy. In AChR+ generalized LOMG, the miR-150-5p, miR-21-5p, and miR-30e-5p levels are elevated and decrease in accordance with the clinical response after immunosuppression. In ocular MG, higher levels of miR-30e-5p discriminate patients who will later generalize from those remaining ocular. In contrast, in MuSK+ MG, the levels of the let-7 miRNA family members are elevated. Studies of circulating miRNA profiles in Lrp4 or agrin antibody-seropositive MG are still lacking. This review summarizes the present knowledge of circulating miRNAs in different subgroups of MG.

Antagonism of the Neonatal Fc Receptor as an Emerging Treatment for Myasthenia Gravis

Myasthenia gravis is an autoimmune disease in which immunoglobulin G (IgG) autoantibodies are formed against the nicotinic acetylcholine receptor (AChR) or other components of the neuromuscular junction. Though effective treatments are currently available, many commonly used therapies have important limitations and alternative therapeutic options are needed for patients. A novel treatment approach currently in clinical trials for myasthenia gravis targets the neonatal Fc receptor (FcRn). This receptor plays a central role in prolonging the half–life of IgG molecules. The primary function of FcRn is salvage of IgG and albumin from lysosomal degradation through the recycling and transcytosis of IgG within cells. Antagonism of this receptor causes IgG catabolism, resulting in reduced overall IgG and pathogenic autoantibody levels. This treatment approach is particularly intriguing as it does not result in widespread immune suppression, in contrast to many therapies in routine clinical use. Experience with plasma exchange and emerging phase 2 clinical trial data of FcRn antagonists provide proof of concept for IgG lowering in myasthenia gravis. Here we review the IgG lifecycle and the relevance of IgG lowering to myasthenia gravis treatment and summarize the available data on FcRn targeted therapeutics in clinical trials for myasthenia gravis.

Frequency and clinical features of treatment-refractory myasthenia gravis

Background

To investigate the frequency and characterize the clinical features of treatment-refractory myasthenia gravis in an Austrian cohort.

Methods

Patient charts of 126 patients with generalized myasthenia gravis and onset between 2000 and 2016 were analyzed retrospectively. Patients were classified as treatment-refractory according to strict, predefined criteria. These mandated patients being at least moderately symptomatic (i.e., MGFA class III) or needing either maintenance immunoglobulins or plasma exchange therapy for at least 1 year in spite of two adequately dosed immunosuppressive drugs. Clinical features and outcome at last follow-up were compared to treatment-responsive patients.

Results

14 out of 126 patients (11.1%) met these criteria of treatment-refractory myasthenia gravis. Treatment-refractory patients had more frequent clinical exacerbations and more often received rescue treatments or a further escalation of immunosuppressive therapies. They also remained more severely affected at last follow-up. An early onset of myasthenia gravis was associated with a higher risk for a refractory course.

Conclusion

A small subgroup of patients with generalized myasthenia gravis do not respond sufficiently to standard therapies. Refractory disease has considerable implications for both patients and health care providers and highlights an unmet need for new treatment options.

Acupuncture for patients with myasthenia gravis: A systematic review protocol

BACKGROUND

The objective of this systematic review protocol is to provide the methods for evaluating the effectiveness and safety of acupuncture on the treatment of myasthenia gravis (MG).

METHODS AND ANALYSIS

We will search randomized controlled trials (RCTs) on this subject in 8 electronic databases and they are Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, PubMed, Chinese Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), the Wan-Fang Database, and Chinese Scientific Journal Database (VIP database). Other relevant literatures will be manually searched as a complement. Only RCTs related to acupuncture for MG will be included, without Language restrictions and limitation of publication types. The risk of bias and trial quality will be assessed by the Cochrane collaboration tool. The study inclusion, data extraction and quality assessment will be conducted independently by 2 reviewers. All data from the studies included will be analyzed by RevMan V.5.3 statistical software.

RESULTS

This study will provide a high-quality synthesis of RCTs on the efficacy and safety of acupuncture as an adjuvant therapy in the treatment of MG.

CONCLUSION

This systemic review will provide high quality evidence to evaluate acupuncture as adjuvant therapy in patients with MG.

PROSPERO REGISTRATION NUMBER

PROSPERO CRD42019133577.

Measuring Clinical Treatment Response in Myasthenia Gravis

In this article we provide an overview of health-related outcome measurement-to better understand what different outcomes used in myasthenia actually measure-and to provide some guidance when choosing measures based on the clinical context and question. In myasthenia, the most commonly used outcome measures are aimed at assessing the signs and symptoms. In this review, we provide a summary of the most commonly used outcome measures. We discuss instruments that gauge disease overall health impact, such as on disability and quality of life. Finally, we discuss other relevant outcomes such as steroid-sparing effects and the role of surrogate markers.

MicroRNA signature associated with treatment response in myasthenia gravis: A further step towards precision medicine

Myasthenia gravis (MG) is an autoimmune disorder affecting neuromuscular transmission currently treated with chronic immunosuppression. Inter-subject variation in treatment response and side effects highlight the need for personalized therapies by identification of biomarkers predictive of drug efficacy in individual patients, still lacking in MG. MicroRNAs (miRNAs) play a key role in immune response and drug metabolism modulation. This study, part of an Italian-Israeli collaborative project, aimed to identify specific miRNAs as biomarkers associated with immunosuppressive treatment response in MG patients. Whole miRNome sequencing, followed by miRNA validation by real-time PCR, was performed in peripheral blood from Italian MG patients (n = 40) classified as responder and non-responder to immunosuppressive therapies. MiRNA sequencing identified 41 miRNAs differentially expressed in non-responder compared to responder Italian MG patients. Validation phase pointed out three miRNAs, miR-323b-3p, -409-3p, and -485-3p, clustered on chromosome 14q32.31, the levels of which were significantly decreased in non-responder versus responder patients, whereas miR-181d-5p and -340-3p showed an opposite trend. ROC curve analysis showed sensitivity and specificity performance results indicative of miR-323b-3p, -409-3p, and -485-3p predictive value for responsiveness to immunosuppressive drugs in MG. Validated miRNAs were further analyzed in blood from responder and non-responder MG patients of the Israeli population (n = 33), confirming a role for miR-323b-3p, -409-3p, -485-3p, -181d-5p and -340-3p as biomarkers of drug efficacy. Gene Ontology enrichment analysis, mRNA target prediction, and in silico modeling for function of the identified miRNAs disclosed functional involvement of the five miRNAs, and their putative target genes, in both immune (i.e. neurotrophin TRK and Fc-epsilon receptor signaling pathways) and drug metabolism processes. Our overall findings thus revealed a blood "miR-323b-3p, -409-3p, -485-3p, -181d-5p, and -340-3p" signature associated with drug responsiveness in MG patients. Its identification sets the basis for precision medicine approaches based on "pharmacomiRs" as biomarkers of drug responsiveness in MG, promising to improve therapeutic success in a cost/effective manner.

Beyond the antibodies: serum metabolomic profiling of myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) is a chronic, potentially debilitating autoimmune disease characterized by weakness and rapid fatigue of the voluntary muscles that worsens on exertion. Left untreated, MG symptoms may cause significant morbidity or even death. To date, no robust biological marker is available to follow the course of the disease. Therefore, new diagnostic approaches and biological markers are essential not only for improved diagnosis of the disease but for improved outcomes.

OBJECTIVES

The present study applied a two-control, multi-label metabolomics profiling approach as a potential strategy for the identification of biomarkers unique to myasthenia gravis (MG).

METHODS

Metabolic analyses using acid- and dansyl-labelled serum from seropositive MG (n = 46), rheumatoid arthritis (RA) (n = 23) and healthy controls (HC) (n = 49) were performed on samples from adult patients presenting to the University of Alberta Hospital neuromuscular and rheumatology clinics. Comparisons between patients with MG vs. HC, and RA vs. HC were made using univariate and multivariate statistics.

RESULTS

Serum biomarker patterns were statistically significantly different between groups. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) models exhibited considerable distinction between all groups. Metabolites were then filtered to remove peak pairs common to both disease cohorts. Combined metabolite panels revealed clear separation between MG and HC for both library-matched (AUROC: 0.92 ± 0.03) and highest AUC patients (AUROC: 0.94 ± 0.05).

CONCLUSION

In patients presenting to the clinic with seropositive MG, metabolomic profiling is capable of distinguishing patients with disease from those without. These results provide an important first step towards a potential biomarker for improving MG identification.

Chinese Herbal Medicine for Myasthenia Gravis: A Systematic Review and Meta-Analysis

Myasthenia gravis (MG) is an acquired autoimmune disease with the disorder of the neuromuscular junction transmission caused by autoantibodies. Currently, various Chinese herbal medicines (CHMs) are widely used for MG. This meta-analysis was conducted to assess the effectiveness and safety of CHMs for MG and its possible mechanisms. Fourteen studies with 1039 individuals were identified by searching seven databases from inception to March 2017. The methodological quality was assessed by using 7-item criteria from the Cochrane's Collaboration tool, and which assessed ≥4 "yes" in the domains were selected for detailed assessment and meta-analysis. All the data were analyzed using Rev-Man 5.3 software. Meta-analysis showed a significant effect of CHM as adjuvant therapy for improving the effectiveness compared with WCM alone or placebo in treating MG (p < 0.01). Moreover, there were fewer adverse effects and relapse rate in total when compared with the control group. The possible mechanisms of CHM for MG are associated with immunoregulation by reconstituting the functional ability of Tregs. In conclusion, despite the apparent positive results, the present evidence supports, to an extent, that CHM can be used for MG patients because of the methodological flaws and CHM heterogeneity. Further rigorous RCT for MG is needed.

Advances in autoimmune myasthenia gravis management

INTRODUCTION

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder with no cure and conventional treatments limited by significant adverse effects and variable benefit. In the last decade, therapeutic development has expanded based on improved understanding of autoimmunity and financial incentives for drug development in rare disease. Clinical subtypes exist based on age, gender, thymic pathology, autoantibody profile, and other poorly defined factors, such as genetics, complicate development of specific therapies. Areas covered: Clinical presentation and pathology vary considerably among patients with some having weakness limited to the ocular muscles and others having profound generalized weakness leading to respiratory insufficiency. MG is an antibody-mediated disorder dependent on autoreactive B cells which require T-cell support. Treatments focus on elimination of circulating autoantibodies or inhibition of effector mechanisms by a broad spectrum of approaches from plasmapheresis to B-cell elimination to complement inhibition. Expert commentary: Standard therapies and those under development are disease modifying and not curative. As a rare disease, clinical trials are challenged in patient recruitment. The great interest in development of treatments specific for MG is welcome, but decisions will need to be made to focus on those that offer significant benefits to patients.

Randomized study of adjunctive belimumab in participants with generalized myasthenia gravis

Objective

To investigate the efficacy and safety of belimumab, a fully human immunoglobulin G1λ monoclonal antibody against B-lymphocyte stimulator, in participants with generalized myasthenia gravis (MG) who remained symptomatic despite standard of care (SoC) therapy.

Methods

Eligible participants with MG were randomized 1:1 to receive IV belimumab 10 mg/kg or placebo in this phase II, placebo-controlled, multicenter, double-blind study (NCT01480596; BEL115123). Participants received SoC therapies throughout the 24-week treatment phase and 12-week follow-up period. The primary efficacy endpoint was mean change from baseline in the Quantitative Myasthenia Gravis (QMG) scale at week 24; safety assessments included the frequency and severity of adverse events (AEs) and serious AEs.

Results

Forty participants were randomized (placebo n = 22; belimumab n = 18). The mean change in QMG score from baseline at week 24 was not significantly different for belimumab vs placebo (p = 0.256). There were no statistically significant differences between treatment groups for secondary endpoints, including the MG Composite and MG–Activity of Daily Living scores. Acetylcholine receptor antibody levels decreased over time in both treatment groups. No unexpected AEs were identified and occurrence was similar in the belimumab (78%) and placebo (91%) groups. One participant receiving placebo died (severe sepsis) during the treatment phase.

Conclusions

The primary endpoint was not met for belimumab in participants with generalized MG receiving SoC. There was no significant difference in mean change in the QMG score at week 24 for belimumab vs placebo. The safety profile of belimumab was consistent with previous systemic lupus erythematosus studies.

Classification of evidence

This study provides Class I evidence that for participants with generalized MG, belimumab did not significantly improve QMG score compared with placebo.

Thymectomy lowers the myasthenia gravis biomarker miR-150-5p

Objective

The aim of the study was to analyze the effect of thymectomy on the proposed disease-specific microRNA (miRNA) biomarkers miR-150-5p and miR-21-5p in patients from the prospective randomized trial of thymectomy in myasthenia gravis (MGTX trial) and to evaluate the longitudinal changes in clinical patterns compared with these miRNA levels.

Methods

Serum samples were obtained from 80 patients with MG who were included in the MGTX trial. Thirty-eight patients were randomized to thymectomy plus prednisone treatment, and 42 patients were randomized to prednisone treatment. Serum samples were analyzed for the expression of miR-150-5p and miR-21-5p, with quantitative reverse transcriptase PCR at baseline and at 12, 24, and 36 months after randomization. The inclusion criteria for participation in the MGTX trial were age 18-65 years, generalized myasthenia gravis (Myasthenia Gravis Foundation of America Class II-IV), disease duration of less than 5 years, and seropositivity for acetylcholine receptor antibodies (AChR+).

Results

Patients treated with thymectomy had lower levels of miR-150-5p at 24 months, both compared with baseline values (p = 0.0011) and the prednisone group (p = 0.04). No change in miRNA levels was found in the prednisone group. Levels of miR-21-5p displayed a negative correlation with the prednisone dose within the prednisone-only group (p ≤ 0.001).

Conclusions

Thymectomy lowers the levels of the proposed biomarker miR-150-5p, which strengthens its position as a potential disease-specific biomarker for AChR+ MG.

Comparative effectiveness clinical trials to advance treatment of myasthenia gravis

Myasthenia gravis (MG) presents many challenges for establishing treatment efficacy through clinical trials. Among these are the rarity and heterogeneity of the disease, spontaneous fluctuations, prolonged latency to effect for many immunosuppressive drugs, and the uncertain generalizability of results from randomized controlled trials (RCTs). Prospective observational study designs may overcome some of these limitations, but attention is required to ensure that internal validity is not compromised. Observational comparative effectiveness research (CER) utilizes data obtained during routine clinical care to evaluate the effectiveness of interventions in real-life practice conditions, thereby improving generalizability to the clinic. Compared with RCTs, observational CER studies may be less resource intensive and costly. Recent advances that have improved the feasibility of CER studies for MG are (1) the development of MG common data elements, (2) the publication of international consensus guidance for MG treatment, and (3) the development of a web-based REDCap database that can be shared and adapted to standardize data collection. This infrastructure could be used for multisite comparisons of commonly used therapies and provides longitudinal information on patient- and clinician-centered MG outcome measures. A challenge is to design studies that address the potential limitations of observational trials, such as confounding and selection and information bias.

Tacrolimus Improves Symptoms of Children With Myasthenia Gravis Refractory to Prednisone

BACKGROUND

Myasthenia gravis tends to affect children in China. Oral pyridostigmine and prednisone could effectively improve the symptoms, but multiple side effects become a major concern after long-term oral prednisone. To avoid the long-term complications of prednisone therapy and to obtain more satisfactory improvement, we tested the efficacy and safety of tacrolimus in children with myasthenia gravis.

METHODS

Children with myasthenia gravis who had not achieved satisfactory improvement or who experienced severe side effects after prednisone therapy were recruited between January 2015 and December 2016 at Tongji Hospital. All the children were treated with tacrolimus 1 mg to 2 mg daily and the dose was adjusted on the basis of the clinical response and the serum concentration. The dosage of prednisone, the severity of symptoms, blood samples, the serum concentration of tacrolimus, and titers of antiacetylcholine receptor antibodies were evaluated every four weeks.

RESULTS

Fourteen children were enrolled. One child withdrew two weeks after the enrollment. Thirteen children have completed the therapy for one year. At the end point, the dosage of prednisone was significantly decreased (P < 0.05), the symptoms were evaluated by the quantitative myasthenia gravis score, and myasthenia gravis-specific manual muscle testing and myasthenia gravis-activities of daily living scores were significantly improved (P < 0.05, P < 0.05, and P < 0.01, respectively). More importantly, ten (76.9%) patients had completely discontinued prednisone, and the major side effects were nearly reversed. The mean titer of antiacetylcholine receptor antibodies significantly dropped from 1.96±2.62 nmol/L to 0.70±1.04 nmol/L (P < 0.05). No severe adverse events were reported.

CONCLUSIONS

Our results suggest that tacrolimus is a promising agent for children with refractory myasthenia gravis. Randomized clinical trials are needed to confirm the observation.

Circulating microRNAs as potential biomarkers in myasthenia gravis patients

MicroRNAs (miRNAs) are small noncoding RNA molecules that bind to specific mRNA targets and regulate a wide range of important biological processes within cells. Circulating miRNAs are released into the extracellular space and can be measured in most biofluids, including blood serum and plasma. Recently, circulating miRNAs have emerged as easily accessible markers in various body fluids with different profiles and quantities specific for different human disorders, including autoimmune diseases. In myasthenia gravis (MG), diagnostic tests such as titers of serum autoantibodies specific for either the acetylcholine receptor (AChR⁺ ) or muscle-specific tyrosine kinase (MuSK⁺ ) do not necessarily reflect disease progression, and there is a great need for reliable objective biomarkers to monitor the disease course and therapeutic response. Recent studies in AChR⁺ MG revealed elevated levels of the immuno-miRNAs miR-150-5p and miR-21-5p. Of particular importance, levels of miR-150-5p were lower in immunosuppressed patients and in patients with clinical improvement following thymectomy. In MuSK⁺ MG, another profile of circulating miRNAs was found, including upregulation of the let-7 family of miRNAs. Here, we summarize the potential role of circulating miRNAs as biomarkers in general and in MG, and highlight important considerations for the analysis of circulating miRNA.

A novel ABCC6 haplotype is associated with azathioprine drug response in myasthenia gravis

OBJECTIVE

We investigated the association of single nucleotide polymorphisms (SNPs) in drug-metabolizing enzymes and transporters (DMETs) with the response to azathioprine (AZA) in patients affected by myasthenia gravis (MG) to determine possible genotype-phenotype correlations.

PATIENTS AND METHODS

Genomic DNA from 180 AZA-treated MG patients was screened through the Affymetrix DMET platform, which characterizes 1931 SNPs in 225 genes. The significant SNPs, identified to be involved in AZA response, were subsequently validated by allelic discrimination and direct sequencing. SNP analysis was carried out using the SNPassoc R package and the haploblocks were determined using haploview software.

RESULTS

We studied 127 patients in the discovery phase and 53 patients in the validation phase. We showed that two SNPs (rs8058694 and rs8058696) found in ATP-binding cassette subfamily C member 6, a subfamily member of ATP-binding cassette genes, constituted a new haplotype associated with AZA response in MG patients in the discovery cohort (P=0.011; odds ratio: 0.40; 95% confidence interval: 0.20-0.83) and in the combined cohort (P=0.04; odds ratio: 1.58).

CONCLUSION

These findings highlight the role that the ATP-binding cassette subfamily C member 6 haplotype may play in AZA drug response. In view of the significant effects and AZA intolerance, these novel SNPs should be taken into consideration in pharmacogenetic profiling for AZA.

Rituximab as treatment for anti-MuSK myasthenia gravis: Multicenter blinded prospective review

OBJECTIVE

To evaluate the efficacy of rituximab in treatment of anti-muscle-specific kinase (MuSK) myasthenia gravis (MG).

METHODS

This was a multicenter, blinded, prospective review, comparing anti-MuSK-positive patients with MG treated with rituximab to those not treated with rituximab. The primary clinical endpoint was the Myasthenia Gravis Status and Treatment Intensity (MGSTI), a novel outcome that combines the Myasthenia Gravis Foundation of America (MGFA) postintervention status (PIS) and the number and dosages of other immunosuppressant therapies used. A priori, an MGSTI of level ≤2 was used to define a favorable outcome. Secondary outcomes included modified MGFA PIS of minimal manifestations or better, mean/median prednisone dose, and mean/median doses of other immunosuppressant drugs.

RESULTS

Seventy-seven of 119 patients with anti-MuSK MG evaluated between January 1, 2005, and January 1, 2015, at 10 neuromuscular centers were selected for analysis after review of limited clinical data by a blinded expert panel. An additional 22 patients were excluded due to insufficient follow-up. Baseline characteristics were similar between the rituximab-treated patients (n = 24) and the controls (n = 31). Median follow-up duration was >3.5 years. At last visit, 58% (14/24) of rituximab-treated patients reached the primary outcome compared to 16% (5/31) of controls (p = 0.002). Number needed to treat for the primary outcome is 2.4. At last visit, 29% of rituximab-treated patients were taking prednisone (mean dose 4.5 mg/day) compared to 74% of controls (mean dose 13 mg/day) (p = 0.001 and p = 0.005).

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for patients with anti-MuSK MG, rituximab increased the probability of a favorable outcome.

Quantitative Myasthenia Gravis Score: a Brazilian multicenter study for translation, cultural adaptation and validation

Objective

To perform the translation, cross-cultural adaptation and validation of the Quantitative Myasthenia Gravis Score (QMGS) to Brazilian Portuguese in accordance with international ethical standards.

Methods

The following steps were taken: (1) implementation of the translation protocol and transcultural adaptation, (2) validation of the adapted content, and (3) assessment of reliability. To check intra- and inter-observer reproducibility, each patient underwent two interviews with interviewer-A and one with B. The QMGS was compared to the Myasthenia Gravis Composite Scale and Myasthenia-specific Quality of Life Questionnaire.

Results

Our study group consisted of 30 patients, with a mean age of 47.6±11.4 years and a mean duration of illness of 11.33±8.49 years. Correlation between the QMGS and MGC was very strong (r = 0.928; p < 0.001) and substantial between the QMGS and MG-QOL 15 (r = 0.737; p < 0.001).

Conclusion

The Brazilian Portuguese translation, and validation of the QMGS was successfully performed.

Tacrolimus in the treatment of myasthenia gravis in patients with an inadequate response to glucocorticoid therapy: randomized, double-blind, placebo-controlled study conducted in China

Background

To determine the efficacy of low-dose, immediate-release tacrolimus in patients with myasthenia gravis (MG) with inadequate response to glucocorticoid therapy in a randomized, double-blind, placebo-controlled study.

Methods

Eligible patients had inadequate response to glucocorticoids (GCs) after ⩾6 weeks of treatment with prednisone ⩾0.75 mg/kg/day or 60–100 mg/day. Patients were randomized to receive 3 mg tacrolimus or placebo daily (orally) for 24 weeks. Concomitant glucocorticoids and pyridostigmine were allowed. Patients continued GC therapy from weeks 1–4; from week 5, the dose was decreased at the discretion of the investigator. The primary efficacy outcome measure was a reduction, relative to baseline, in quantitative myasthenia gravis (QMG) score assessed using a generalized linear model; supportive analyses used alternative models.

Results

Of 138 patients screened, 83 [tacrolimus (n = 45); placebo (n = 38)] were enrolled and treated. The change in adjusted mean QMG score from baseline to week 24 was −4.9 for tacrolimus and −3.3 for placebo (least squares mean difference: –1.7, 95% confidence interval: −3.5, −0.1; p = 0.067). A post-hoc analysis demonstrated a statistically significant difference for QMG score reduction of ⩾4 points in the tacrolimus group (68.2%) versus the placebo group (44.7%; p = 0.044). Adverse event profiles were similar between treatment groups.

Conclusions

Tacrolimus 3 mg treatment for patients with MG and inadequate response to GCs did not demonstrate a statistically significant improvement in the primary endpoint versus placebo over 24 weeks; however, a post-hoc analysis demonstrated a statistically significant difference for QMG score reduction of ⩾4 points in the tacrolimus group versus the placebo group. This study was limited by the low number of patients, the absence of testing for acetylcholine receptor antibody and the absence of stratification by disease duration (which led to a disparity between the two groups).

ClinicalTrials.gov identifier: NCT01325571

Peritoneal recurrence of thymoma treated by surgery and hyperthermic intraperitoneal chemotherapy

Thymomas are rare (1,5 cases/million) and typically occur in adults with a median age of 50 years old. Thymomas are indolent with a 10-year overall survival for resected stage II thymomas of 70%. Late relapses occur in 20% of the cases, and distant metastasis from thymoma is rare. Peritoneal recurrence of thymoma treated with surgery associated with hyperthermic intraperitoneal chemotherapy (HIPEC) has not been described in the literature. This report manages peritoneal recurrence of thymoma with HIPEC, suggesting that aggressive therapies may decrease the risk of recurrence.

The Role of Osteopontin and Its Gene on Glucocorticoid Response in Myasthenia Gravis

Biomarkers that assess treatment response for patients with the autoimmune disorder, myasthenia gravis (MG), have not been evaluated to a significant extent. We hypothesized the pro-inflammatory cytokine, osteopontin (OPN), may be associated with variability of response to glucocorticoids (GCs) in patients with MG. A cohort of 250 MG patients treated with standardized protocol of GCs was recruited, and plasma OPN and polymorphisms of its gene, secreted phosphoprotein 1 (SPP1), were evaluated. Mean OPN levels were higher in patients compared to healthy controls. Carriers of rs11728697*T allele (allele definition: one of two or more alternative forms of a gene) were more frequent in the poorly GC responsive group compared to the GC responsive group indicating an association of rs11728697*T allele with GC non-responsiveness. One risk haplotype (AGTACT) was identified associated with GC non-responsiveness compared with GC responsive MG group. Genetic variations of SPP1 were found associated with the response to GC among MG patients.

Outcome Measures in Myasthenia Gravis: Incorporation Into Clinical Practice

The development of validated assessment tools for evaluating disease status and response to interventions in patients with myasthenia gravis (MG) has been driven by clinical studies of emerging MG therapies. However, only a small proportion of MG-focused neurology practices have adopted these assessment tools for routine clinical use. This article reviews the suitability of 5 assessment instruments for incorporation into clinical practice, which should be driven by their ability to contribute to improved patient outcomes, and to be implemented within practice personnel and resource constraints. It is recommended that assessments based on both physician-evaluated and patient-reported outcomes be selected, to adequately evaluate both point-in-time symptom load and functional impact of MG symptoms over time. Provider resource allocation and reimbursement issues may be the most significant roadblocks to successful ongoing use of these tools; to that end, the addition of regular assessments to MG standards of care is recommended.

Neuromuscular junction disorders

Diseases of the neuromuscular junction comprise a wide range of disorders. Antibodies, genetic mutations, specific drugs or toxins interfere with the number or function of one of the essential proteins that control signaling between the presynaptic nerve ending and the postsynaptic muscle membrane. Acquired autoimmune disorders of the neuromuscular junction are the most common and are described here. In myasthenia gravis, antibodies to acetylcholine receptors or to proteins involved in receptor clustering, particularly muscle-specific kinase, cause direct loss of acetylcholine receptors or interfere with the agrin-induced acetylcholine receptor clustering necessary for efficient neurotransmission. In the Lambert-Eaton myasthenic syndrome (LEMS), loss of the presynaptic voltage-gated calcium channels results in reduced release of the acetylcholine transmitter. The conditions are generally recognizable clinically and the diagnosis confirmed by serologic testing and electromyography. Screening for thymomas in myasthenia or small cell cancer in LEMS is important. Fortunately, a wide range of symptomatic treatments, immunosuppressive drugs, or other immunomodulating therapies is available. Future research is directed to understanding the pathogenesis, discovering new antigens, and trying to develop disease-specific treatments.

Brazilian-Portuguese translation, cross-cultural adaptation and validation of the Myasthenia Gravis Composite scale. A multicentric study

Objective

To perform the translation, cultural adaptation and validation of the Myasthenia Gravis Composite (MGC) scale in Brazil.

Methods

The study was conducted at three neuromuscular disease research centers in accordance with the international ethical standards, following a multi-modal approach and was conducted in three steps consisting of translation, cultural adaptation, and validation according to international guidelines. The final version of the MGC was applied in a sample of 27 MG patients and the total score was compared to a Portuguese version of the MG-QOL-15.

Results

The internal consistency verified by Cohen's Kappa test was excellent (0.766). The correlation between the MGC and MG-QOL-15 was strong (R = 0.777; p = 0.000). No significant differences were found between the responses of patients in the first and second applications of the MGC.

Conclusion

The MGC scale, validated into Brazilian Portuguese, has proven to be a reliable instrument that is easy to use, and is highly reproducible.

Activity limitations in myasthenia gravis and relation to clinical variables

INTRODUCTION

It is unknown how fluctuations in muscle weakness affect activity limitations in myasthenia gravis patients and how the severity of these limitations compares with published data on other neuromuscular disorders (NMD).

METHODS

In this study we analyzed ACTIVLIM (acronym of "ACTIVity LIMitations") and quantitative myasthenia gravis (QMG) scores. We assessed the impact of QMG and other clinical variables on ACTIVLIM, using B coefficients.

RESULTS

The mean ACTIVLIM score in 118 MG patients was 3.3. There was a correlation between QMG and ACTIVLIM (B coefficient = -0.206, P < 0.001) and between changes in both scores (B coefficient = -0.175, P = 0.002). Men and patients without another autoimmune disease had a better ACTIVLIM score (B coefficient = 0.785, P = 0.015 and B coefficient = 0.998, P = 0.008, respectively).

CONCLUSIONS

The ACTIVLIM score in MG is higher than in other NMD. Fluctuations in QMG correlated significantly with changes in ACTIVLIM. Muscle Nerve 56: 64-70, 2017.

Determinants of quality of life in Brazilian patients with myasthenia gravis

OBJECTIVES

The aims of the current study were 1) to evaluate the reliability and validity of the Brazilian version of the 15-item Myasthenia Gravis Quality of Life Scale and 2) to investigate the quality of life of Brazilian patients with myasthenia gravis and its determinants.

METHODS

This cross-sectional study included 69 patients with myasthenia gravis who underwent neurological evaluation and completed questionnaires regarding quality of life (the 36-item Short Form of the Medical Outcomes Study and the 15-item Myasthenia Gravis Quality of Life Scale), anxiety and depressive symptoms.

RESULTS

The Brazilian version of the 15-item Myasthenia Gravis Quality of Life Scale showed high internal consistency and good concurrent validity with the 36-item Short Form of the Medical Outcomes Study and its subscales. Determinants of quality of life in Brazilian patients with myasthenia gravis included the current status of myasthenia gravis as assessed by the Myasthenia Gravis Composite, the current prednisone dose and the levels of anxiety and depression.

CONCLUSION

The Brazilian version of the 15-item Myasthenia Gravis Quality of Life Scale is a valid instrument. Symptom severity, prednisone dosage and anxiety and depression levels impact the quality of life of patients with myasthenia gravis.

A randomized controlled trial of methotrexate for patients with generalized myasthenia gravis

OBJECTIVE

To determine the steroid-sparing effect of methotrexate (MTX) in patients with symptomatic generalized myasthenia gravis (MG).

METHODS

We performed a 12-month multicenter, randomized, double-blind, placebo-controlled trial of MTX 20 mg orally every week vs placebo in 50 acetylcholine receptor antibody-positive patients with MG between April 2009 and August 2014. The primary outcome measure was the prednisone area under the dose-time curve (AUDTC) from months 4 to 12. Secondary outcome measures included 12-month changes of the Quantitative Myasthenia Gravis Score, the Myasthenia Gravis Composite Score, Manual Muscle Testing, the Myasthenia Gravis Quality of Life, and the Myasthenia Gravis Activities of Daily Living.

RESULTS

Fifty-eight patients were screened and 50 enrolled. MTX did not reduce the month 4-12 prednisone AUDTC when compared to placebo (difference MTX - placebo: -488.0 mg, 95% confidence interval -2,443.4 to 1,467.3, p = 0.26); however, the average daily prednisone dose decreased in both groups. MTX did not improve secondary measures of MG compared to placebo over 12 months. Eight participants withdrew during the course of the study (1 MTX, 7 placebo). There were no serious MTX-related adverse events. The most common adverse event was nonspecific pain (19%).

CONCLUSIONS

We found no steroid-sparing benefit of MTX in MG over 12 months of treatment, despite being well-tolerated. This study demonstrates the challenges of conducting clinical trials in MG, including difficulties with recruitment, participants improving on prednisone alone, and the need for a better understanding of outcome measure variability for future clinical trials.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that for patients with generalized MG MTX does not significantly reduce the prednisone AUDTC over 12 months of therapy.

Efficacy of prednisone for the treatment of ocular myasthenia (EPITOME): A randomized, controlled trial

INTRODUCTION

In this study we evaluated the safety, tolerability, and efficacy of prednisone in patients with ocular myasthenia gravis (OMG) concurrently treated with pyridostigmine.

METHODS

This investigation was a randomized, double-blind, placebo-controlled trial. Participants whose symptoms failed to remit on pyridostigmine were randomized to receive placebo or prednisone, initiated at 10 mg every other day, and titrated to a maximum of 40 mg/day over 16 weeks. The primary outcome measure was treatment failure.

RESULTS

Fewer subjects were randomized than the 88 planned. Of the 11 randomized, 9 completed 16 weeks of double-blind therapy. Treatment failure incidence was 100% (95% CI 48%-100%) in the placebo group (n = 5) vs. 17% (95% CI 0%-64%) in the prednisone group, P = 0.02 (n = 6). Median time to sustained minimal manifestation status (MMS) was 14 weeks, requiring an average prednisone dose of 15 mg/day. Adverse events were infrequent and generally mild in both groups.

CONCLUSIONS

A strategy of low-dose prednisone with gradual escalation appears to be safe, well-tolerated, and effective in treating OMG.

Myasthenia gravis: a clinical-immunological update

Myasthenia gravis (MG) is the archetypic disorder of both the neuromuscular junction and autoantibody-mediated disease. In most patients, IgG1-dominant antibodies to acetylcholine receptors cause fatigable weakness of skeletal muscles. In the rest, a variable proportion possesses antibodies to muscle-specific tyrosine kinase while the remainder of seronegative MG is being explained through cell-based assays using a receptor-clustering technique and, to a lesser extent, proposed new antigenic targets. The incidence and prevalence of MG are increasing, particularly in the elderly. New treatments are being developed, and results from the randomised controlled trial of thymectomy in non-thymomatous MG, due for release in early 2016, will be of particular clinical value. To help navigate an evidence base of varying quality, practising clinicians may consult new MG guidelines in the fields of pregnancy, ocular and generalised MG (GMG). This review focuses on updates in epidemiology, immunology, therapeutic and clinical aspects of GMG in adults.

Validation of the Besta Neurological Institute rating scale for myasthenia gravis

INTRODUCTION

We validated the scale for myasthenia gravis (MG) developed at the Neurological Institute Foundation of Milan (INCB-MG scale).

METHODS

A total of 174 patients were evaluated with the INCB-MG and compared with the MG Composite (MGC) as the gold standard. Dimensionality, reliability, and validity of the INCB-MG scale were studied by principal component factor analysis, Cronbach alpha, and Pearson correlation coefficients; interobserver reliability was calculated by the weighted Cohen K coefficient.

RESULTS

Generalized and bulbar INCB-MG subscales were unidimensional with excellent consistency; the INCB-MG and MGC scales were strongly correlated. Fatigability assessment was correlated with the INCB-MG generalized, bulbar, and respiratory subscales.

CONCLUSIONS

The INCB-MG scale is a reliable tool to assess MG and is strongly correlated with the MGC. The INCB-MG scale is a valid tool for every day practice and should be further investigated for its application in clinical trials.

Ephedrine as add-on therapy for patients with myasthenia gravis: protocol for a series of randomised, placebo-controlled n-of-1 trials

INTRODUCTION

Myasthenia gravis (MG), a rare neuromuscular disease, is often initially treated using acetylcholinesterase inhibitors. Patients who do not respond adequately depend on the use of corticosteroids or other immunosuppressive medication, but these may have serious side effects. Clinical observations suggest that ephedrine can diminish, postpone or even prevent the need for immunosuppressive therapy when added to acetylcholinesterase inhibitors or low-dose prednisone. In the Netherlands, ephedrine is not licensed for MG nor is reimbursement guaranteed. MG is a rare condition, and ephedrine might be indicated only in a subset of patients. Thus, randomised controlled trials comparing large groups are difficult to conduct. We, therefore, aim to aggregate data from a small series of n-of-1 trials (also known as single patient trials) to assess the effect of ephedrine as add-on treatment for MG.

METHODS AND ANALYSIS

Single-centre, placebo-controlled, double-blind, randomised, multiple crossover n-of-1 studies in 4 adult patients with generalised MG who show inadequate improvement on pyridostigmine and/or immunosuppressive drugs. Each n-of-1 trial has 3 cycles of two 5-day intervention periods.

TREATMENT

25 mg ephedrine or placebo, twice daily.

MAIN OUTCOME MEASURE

Quantitative Myasthenia Gravis (QMG) test.

STATISTICAL ANALYSIS

fixed effects linear model for QMG for all patients combined.

SECONDARY OUTCOME MEASURES

Clinical: effects on MG-Composite and MG-Activities of Daily Living (MG-ADL) scales; QMG at individual level; adverse events. Acceptability of trial design: number of patients eligible and enrolled; number of treatment cycles completed; patients' and caregivers' experiences.

ETHICS AND DISSEMINATION

This study was approved by the Medical Ethics Committee of Leiden University Medical Center, No. P14.108. Results of the trial will be reported in a peer-reviewed publication. Regulatory stakeholders will comment on the suitability of the trial for market authorisation and reimbursement purposes.

TRIAL REGISTRATION NUMBER

This study is registered under EudraCT number 2014-001355-23, protocol no. 40960, V.1.0, registration date 27 March 2014.

Disease specific signature of circulating miR-150-5p and miR-21-5p in myasthenia gravis patients

PURPOSE

Reliable biological markers for patients with the autoimmune neuromuscular disorder myasthenia gravis (MG) are lacking. We determined whether levels of the circulating immuno-microRNAs miR-150-5p and miR-21-5p were elevated in sera from clinically heterogeneous MG patients, with and without immunosuppression, as compared to healthy controls and patients with other autoimmune disorders.

METHODS

Sera from 71 MG patients and 55 healthy controls (HC) were analyzed for the expression levels of miR-150-5p and miR-21-5p with qRT-PCR. Sera were also assayed from 23 patients with other autoimmune disorders (AID; psoriasis, Addison's and Crohn's diseases).

RESULTS

34 MG patients had no immunosuppressive drug treatment (MG-0) and 37 patients were under stable immunosuppressive drug treatment since ≥ 6 months (MG+IMM). Serum levels of miR-150-5p and miR-21-5p were higher in the MG-0 patients compared to HC (p<0.0001). Further, miR-150-5p levels were 41% lower and miR-21-5p levels were 25% lower in the MG+IMM compared to MG-0 (p=0.0051 and 0.0419). In the AID patients, mean miR-150-5p and miR-21-5p were comparable with healthy controls (p=0.66).

CONCLUSIONS

The immuno-microRNAs miR-150-5p and miR-21-5p show a disease specific signature, which suggests these microRNAs as possible biological autoimmune markers of MG.

How clinical trials of myasthenia gravis can inform pre-clinical drug development

Pre-clinical evaluations often provide the rationale for therapeutic assessments in humans; however, in many diseases an agent found successful in animal models does not show efficacy in human subjects. Our contention is that the approach of rigorous, clinical trials can be used to inform how preclinical assessments should be performed. Clinical trials in humans are carefully designed investigations executed with consideration of critical methodological issues, such as pre-specified entrance criteria and validated, outcome measures coupled with power analysis to identify sample size. Blinding of evaluators of subjective measures and randomization of subjects are also critical aspects of trial performance. Investigative agents are also tested in subjects with active disease, rather than prior to disease induction as in some pre-clinical assessments. Application of standard procedures, including uniform reporting standards, would likely assist in reproducibility of pre-clinical experiments. Adapting methods of clinical trial performance will likely improve the success rate of therapeutics to ultimately achieve human use.

Thymectomy for non-thymomatous myasthenia gravis: a propensity score matched study

Background

The efficacy of thymectomy in patients with non-thymomatous Myasthenia Gravis (MG) is still unclear. Main limitations have been variable outcome definitions, lack of a control group and adjustment for confounding.

Objective

To study the efficacy of thymectomy in achieving remission or minimal manifestation (R/MM) status in patients with non-thymomatous MG.

Methods

Patients with generalized MG and minimum follow-up of 6 months were included. Demographic data and treatments were recorded, as well as the MGFA post-intervention status at the last visit. Propensity scores were used to create a matched cohort of treated and untreated patients. Standard and Bayesian Cox models were used to study treatment effects.

Results

Of 395 patients included, 183(46%) had a thymectomy. Thymectomy patients were younger (p < 0.001), with more females (p < 0.001) and more patients in MGFA classes 4–5 at diagnosis (p = 0.01). A matched cohort of thymectomized patients and controls (n = 98) was created. The hazard ratio (HR) for the matched cohort was 1.9 (CI:1.6-2.3), favoring thymectomy. The predicted R/MM rate was 21% in treated and 6% in controls at 5 years (Absolute difference:15%). A Bayesian Cox model for the matched cohort had an estimated probability of thymectomy efficacy (HR > 1) of 96% using a non-informative prior, and 79% using a skeptical prior.

Discussion

When controlling for potential confounders, thymectomized patients had a higher probability of achieving R/MM status through time compared to controls. This study provides class III evidence of the efficacy of thymectomy in non-thymomatous myasthenia gravis.

The clinical absolute and relative scoring system-a quantitative scale measuring myasthenia gravis severity and outcome used in the traditional Chinese medicine

Myasthenia gravis (MG) is a chronic autoimmune disease caused by autoantigen against the nicotine acetylcholine receptor at the neuromuscular junction. With modern treatment facilities, the treatment effect and outcome for MG has been greatly improved with MG and non-MG patients enjoying the same life expectancy. Many classifications of disease distribution and severity have been set up and tested all over the world, mainly in the western world. However, the absolute and relative scoring system for evaluating the severity and treatment effect of MG in China where traditional Chinese medicine (TCM) has been practiced for thousands of years has not been introduced worldwide. The TCM has achieved a great success in the treatment of MG in the country with a huge population. This article serves to introduce this scoring system to the world.

Evaluation of the quality of guidelines for myasthenia gravis with the AGREE II instrument

Background

Clinical practice guidelines (CPGs) are systematically developed statements to assist practitioners in making decisions about appropriate healthcare in specific clinical circumstances. The methodological quality of CPGs for myasthenia gravis (MG) are unclear.

Objective

To critically evaluate the methodological quality of CPGs for MG using AGREE II instrument.

Method

A systematical search strategy on PubMed, EMBASE, DynaMed, the National Guideline Clearinghouse (NGC) and the Chinese Biomedical Literature database (CBM) was performed on September 20th 2013. All guidelines related to MG were evaluated with AGREE II. The software used for analysis was SPSS 17.0.

Results

A total of 15 CPGs for MG met the inclusion criteria (12 CPGs in English, 3 CPGs in Chinese). The overall agreement among reviews was moderate or high (ICC >0.70). The mean scores (mean ± SD) for al six domains were presented as follows: scope and purpose (60.93% ±16.62%), stakeholder involvement (40.93% ±20.04%), rigor of development (37.22% ±30.46%), clarity of presentation (64.26% ±16.36%), applicability (28.19% ±20.56%) and editorial independence (27.78% ±28.28%). Compared with non-evidence-based CPGs, evidence-based CPGs had statistically significant higher quality scores for all AGREE II domains (P<0.05). All domain scores appear slightly higher for CPGs published after AGREE II instrument development and validation (P>0.05). The quality scores of CPGs developed by NGC/AAN were higher than the quality scores of CPGs developed by other organizations for all domains. The difference was statistically significant for all domains with the exception of clarity of presentation (P = 0.07).

Conclusions

The qualities of CPGs on MG were generally acceptable with several flaws. The AGREE II instrument should be adopted by guideline developers, particularly in China.

Intravenous immunoglobulin as treatment for myasthenia gravis: current evidence and outcomes

We examined the current evidence for the efficacy of IV immunoglobulin (IVIG) in myasthenia gravis (MG) and the outcomes used to demonstrate this efficacy. There is class 1 evidence for the use of short-term IVIG in MG patients worsening MG and also good evidence for IVIG use in myasthenic crisis. For long-term maintenance therapy, controlled studies are lacking and the evidence is limited to class III retrospective studies. The clinical scales, serological, electrophysiological, and patient-reported quality of life outcomes with IVIG have been assessed. At this time, the quantitative myasthenia gravis score, a functional scale, remains the preferable outcome measure as it has demonstrated responsiveness in the clinical trial setting, but a scale incorporating patient-reported outcomes and the patients complaint of fatigue is likely to be preferable. The MG-composite is such a scale, but has measurement limitations that may reduce its sensitivity. Across trials, IVIG has generally been well tolerated.

Survivin as a potential mediator to support autoreactive cell survival in myasthenia gravis: a human and animal model study

The mechanisms that underlie the development and maintenance of autoimmunity in myasthenia gravis are poorly understood. In this investigation, we evaluate the role of survivin, a member of the inhibitor of apoptosis protein family, in humans and in two animal models. We identified survivin expression in cells with B lymphocyte and plasma cells markers, and in the thymuses of patients with myasthenia gravis. A portion of survivin-expressing cells specifically bound a peptide derived from the alpha subunit of acetylcholine receptor indicating that they recognize the peptide. Thymuses of patients with myasthenia gravis had large numbers of survivin-positive cells with fewer cells in the thymuses of corticosteroid-treated patients. Application of a survivin vaccination strategy in mouse and rat models of myasthenia gravis demonstrated improved motor assessment, a reduction in acetylcholine receptor specific autoantibodies, and a retention of acetylcholine receptor at the neuromuscular junction, associated with marked reduction of survivin-expressing circulating CD20+ cells. These data strongly suggest that survivin expression in cells with lymphocyte and plasma cell markers occurs in patients with myasthenia gravis and in two animal models of myasthenia gravis. Survivin expression may be part of a mechanism that inhibits the apoptosis of autoreactive B cells in myasthenia gravis and other autoimmune disorders.

Stable expression of human muscle-specific kinase in HEp-2 M4 cells for automatic immunofluorescence diagnostics of myasthenia gravis

Muscle-specific kinase (MuSK) belongs to the nicotinic acetylcholine receptor complex which is targeted by pathogenic autoantibodies causing Myasthenia gravis. While up to 95% of patients with generalized Myasthenia gravis were shown to be positive for acetylcholine receptor-specific autoantibodies, up to 70% of the remaining patients develop autoantibodies against MuSK. Discrimination of the autoantibody specificity is important for therapy of Myasthenia gravis. Recently, the new automatic fluorescence assessment platform AKLIDES has been developed for immunofluorescence-based diagnostics of autoimmune diseases. In order to establish an AKLIDES procedure for the detection of MuSK-specific autoantibodies (anti-MuSK), we developed a recombinant HEp-2 cell clone expressing the human MuSK cDNA. Here we show at the mRNA and protein level that the cell clone HEp-2 M4 stably expresses human MuSK. We provide evidence for a localization of MuSK at the cell membrane. Using cell clone HEp-2 M4 on the AKLIDES system, we investigated 34 patient sera that were previously tested anti-MuSK positive by radioimmunoassay as positive controls. As negative controls, we tested 29 acetylcholine receptor-positive but MuSK-negative patient sera, 30 amytrophic lateral sclerosis (ALS) patient sera and 45 blood donors. HEp-2 M4 cells revealed a high specificity for the detection of MuSK autoantibodies from 25 patient sera assessed by a specific pattern on HEp-2 M4 cells. By using appropriate cell culture additives, the fraction of cells stained positive with anti-MuSK containing sera can be increased from 2-16% to 10-48%, depending on the serum. In conclusion, we provide data showing that the novel recombinant cell line HEp-2 M4 can be used to screen for anti-MuSK with the automatic AKLIDES system.