Dataset Information

Correlation of anti-acetylcholine receptor antibody levels and long-term outcomes of juvenile myasthenia gravis in Taiwan: a case control study.

ABSTRACT:

Background

Myasthenia gravis is the most common disease affecting the neuromuscular junction. The most common etiology among patients with juvenile myasthenia gravis is the production of antibodies against the acetylcholine receptor. However, the clinical outcome in relation to serum levels of anti-acetylcholine receptor antibodies in juvenile myasthenia gravis has rarely been discussed. We aimed to analyze the correlation between the presence of anti-acetylcholine receptor antibodies and outcome in juvenile myasthenia gravis.

Methods

Patients diagnosed with juvenile myasthenia gravis younger than of 20?years of age were retrospectively recruited from January 1995 to February 2017 in a tertiary referral medical center. According to the Myasthenia Gravis Foundation of America outcome scale, the primary outcome was complete symptom remission and cessation of medications for at least 1?year measured 2?years after diagnosis. Secondary outcome was complete symptom remission at the last outpatient clinic.

Results

A total of 54 patients were followed up for over 2?years. Nine patients (9/54, 16.7%) achieved complete remission without medication use at 2 years after diagnosis. Thirteen (24.1%) patients achieved complete remission during longer follow-up periods. Those with negative anti-acetylcholine receptor antibodies were more likely to achieve complete remission at 2?years (6/15 [40%] vs. 3/39 [7.7%], 95% Confidence interval [CI] 1.670 to 38.323) and at the last outpatient clinic follow-up (8/15 [53.3%] vs. 5/39 [12.8%], 95% CI 2.367 to 20.704). Thirteen patients with comorbid autoimmune thyroid diseases were older than those without disease (11.8?±?5.8?years old vs. 8.0?±?6.3?years old, 95% CI 0.018 to 7.33). Moreover, patients negative for anti-acetylcholine receptor antibodies were less likely comorbid with autoimmune thyroid disease (1/35 [2.9%] vs. 12/71 [16.9%], 95% CI 0.018 to 1.161).

Conclusions

Juvenile myasthenia gravis patients without anti-acetylcholine antibodies exhibited significantly increased complete remission rates and a reduced likelihood of comorbid autoimmune thyroid diseases compared with those with anti-acetylcholine receptor antibodies among Chinese.

SUBMITTER: Chou CC

PROVIDER: S-EPMC6637626 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Publications

Correlation of anti-acetylcholine receptor antibody levels and long-term outcomes of juvenile myasthenia gravis in Taiwan: a case control study.

Chou Cheng-Che CC Su I-Chen IC Chou I-Jun IJ Lin Jainn-Jim JJ Lan Shih-Yun SY Wang Yi-Shan YS Kong Shu-Sing SS Chen Yun-Ju YJ Hsieh Meng-Ying MY Hung Po-Cheng PC Wang Huei-Shyong HS Chou Min-Liang ML Lin Kuang-Lin KL

BMC neurology 20190718 1

<h4>Background</h4>Myasthenia gravis is the most common disease affecting the neuromuscular junction. The most common etiology among patients with juvenile myasthenia gravis is the production of antibodies against the acetylcholine receptor. However, the clinical outcome in relation to serum levels of anti-acetylcholine receptor antibodies in juvenile myasthenia gravis has rarely been discussed. We aimed to analyze the correlation between the presence of anti-acetylcholine receptor antibodies an ...[more]

PMID: 31319795

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Project description:Juvenile Myasthenia Gravis (JMG) is a rare disorder, defined as myasthenia gravis in children younger than 18 years of age. While clinical phenotypes are similar to adults, there are a number of caveats that influence management: broader differential diagnoses; higher rates of spontaneous remission; and the need to initiate appropriate treatment early, to avoid the long-term physical and psychosocial morbidity. Current practice is taken from treatment guidelines for adult MG or individual experience, with considerable variability seen across centers. We discuss our approach to treating JMG, in a large specialist JMG service, and review currently available evidence and highlight potential areas for future research. First-line treatment of generalized JMG is symptomatic management with pyridostigmine, but early use of immunosuppression, where good control is not achieved is important. Oral prednisolone is used as first-line immunosuppression with appropriate prevention and monitoring of side effects. Second-line therapies including azathioprine and mycophenolate may be considered where there is: no response to steroids, inability to wean to a reasonable minimum effective dose or if side-effects are intolerable. Management of ocular JMG is similar, but requires close involvement of ophthalmology in young children to prevent amblyopia. Muscle-specific tyrosine kinase (MuSK)-JMG show a poorer response to pyridostigmine and anecdotal evidence suggests that rituximab should be considered as second-line immunosuppression. Thymectomy is indicated in any patient with a thymoma, and consideration should be given in acetylcholine receptor (AChR) positive JMG allowing time for spontaneous remission. The benefit is less clear in ocular JMG and is not advised in MuSK-JMG. Children experiencing a myasthenic crisis require urgent hospital admission with access to the intensive care unit. PLEX is preferred over IVIG due to rapid onset of action, but this needs to be balanced with feasibility in very young children. Key questions remain in the management of JMG: when to initiate both first- and second-line treatments, choosing between steroid-sparing agents, and determining the optimal dose and treatment duration. We feel that given the rarity of this disease, the establishment of national registries and collaboration across groups will be needed to address these issues and facilitate future drug trials in JMG.

Project description:Only around 80% of patients with generalized myasthenia gravis (MG) have serum antibodies to acetylcholine receptor [AChR; acetylcholine receptor antibody positive myasthenia gravis (AChR-MG)] by the radioimmunoprecipitation assay used worldwide. Antibodies to muscle specific kinase [MuSK; MuSK antibody positive myasthenia gravis (MuSK-MG)] make up a variable proportion of the remaining 20%. The patients with neither AChR nor MuSK antibodies are often called seronegative (seronegative MG, SNMG). There is accumulating evidence that SNMG patients are similar to AChR-MG in clinical features and thymic pathology. We hypothesized that SNMG patients have low-affinity antibodies to AChR that cannot be detected in solution phase assays, but would be detected by binding to the AChRs on the cell membrane, particularly if they were clustered at the high density that is found at the neuromuscular junction. We expressed recombinant AChR subunits with the clustering protein, rapsyn, in human embryonic kidney cells and tested for binding of antibodies by immunofluorescence. To identify AChRs, we tagged either AChR or rapsyn with enhanced green fluorescence protein, and visualized human antibodies with Alexa Fluor-labelled secondary or tertiary antibodies, or by fluorescence-activated cell sorter (FACS). We correlated the results with the thymic pathology where available. We detected AChR antibodies to rapsyn-clustered AChR in 66% (25/38) of sera previously negative for binding to AChR in solution and confirmed the results with FACS. The antibodies were mainly IgG1 subclass and showed ability to activate complement. In addition, there was a correlation between serum binding to clustered AChR and complement deposition on myoid cells in patients' thymus tissue. A similar approach was used to demonstrate that MuSK antibodies, although mainly IgG4, were partially IgG1 subclass and capable of activating complement when bound to MuSK on the cell surface. These observations throw new light on different forms of MG paving the way for improved diagnosis and management, and the approaches used have applicability to other antibody-mediated conditions.

Project description:ObjectiveTo determine whether rituximab is safe and potentially beneficial, warranting further investigation in an efficacy trial for acetylcholine receptor antibody-positive generalized MG (AChR-Ab+ gMG).MethodsThe B-Cell Targeted Treatment in MG (BeatMG) study was a randomized, double-blind, placebo-controlled, multicenter phase-2 trial that utilized a futility design. Individuals 21-90 years of age, with AChR-Ab+ gMG (MG Foundation of America Class II-IV) and receiving prednisone ≥15 mg/day were eligible. The primary outcome was a measure of steroid-sparing effect, defined as the proportion achieving ≥75% reduction in mean daily prednisone dose in the 4-weeks prior to week 52 and with clinical improvement or no significant worsening as compared to the 4-week period prior to randomization. The co-primary outcome was safety. Secondary outcomes included MG-specific clinical assessments. Fifty-two individuals were randomized (1:1) to either a two-cycle rituximab/placebo regimen, with follow-up through 52-weeks.ResultsOf the 52 participants included, mean (±SD) age at enrollment was 55.1 (±17.1) years; 23 (44.2%) were female, and 31 (59.6%) were MGFA Class II. The mean (±SD) baseline prednisone dose was 22.1 (±9.7) mg/day. The primary steroid-sparing outcome was achieved in 60% of those on rituximab vs. 56% on placebo. The study reached its futility endpoint (p=0.03) suggesting that the pre-defined clinically meaningful improvement of 30% due to rituximab over placebo was unlikely to be achieved in a subsequent, larger trial. No safety issues identified.ConclusionsWhile rituximab was safe and well-tolerated, these results suggest that there is a low probability of observing the defined clinically meaningful steroid-sparing effect over a 12-month period in a phase-3 trial of mild-moderately symptomatic AChR-Ab+ gMG.Classification of evidenceThis study provides Class I evidence that for mild-to-moderate AChR-Ab+ gMG, compared with placebo, rituximab is safe but unlikely to reduce steroid use by an absolute difference of at least 30% at 1 year.Trial registrationClinicalTrials.gov Identifier: NCT02110706.

Dataset Information

Correlation of anti-acetylcholine receptor antibody levels and long-term outcomes of juvenile myasthenia gravis in Taiwan: a case control study.

Background

Methods

Results

Conclusions

Publications

Correlation of anti-acetylcholine receptor antibody levels and long-term outcomes of juvenile myasthenia gravis in Taiwan: a case control study.

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