Clinical and immunological predictors of prognosis for Japanese patients with thymoma-associated myasthenia gravis

Paraneoplastic autoimmune neurologic disorders associated with thymoma

Thymoma is often associated with paraneoplastic neurologic diseases. Neural autoantibody testing is an important tool aiding diagnosis of thymoma and its autoimmune neurologic complications. Autoantibodies specific for muscle striational antigens and ion channels of the ligand-gated nicotinic acetylcholine receptor superfamily are the most prevalent biomarkers. The autoimmune neurologic disorders associating most commonly with thymoma are myasthenia gravis (MG), peripheral nerve hyperexcitability (neuromyotonia and Morvan syndrome), dysautonomia, and encephalitis. Patients presenting with these neurologic disorders should be screened for thymoma at diagnosis. Although they can cause profound disability, they usually respond to immunotherapy and treatment of the thymoma. Worsening of the neurologic disorder following surgical removal of a thymoma may herald tumor recurrence. Prompt recognition of paraneoplastic neurologic disorders is critical for patient management. A multidisciplinary approach is required for optimal management of neurologic autoimmunity associated with thymoma.

Poor responses and adverse outcomes of myasthenia gravis after thymectomy: Predicting factors and immunological implications

Myasthenia gravis (MG) has been recognized as a series of heterogeneous but treatable autoimmune conditions. As one of the indispensable therapies, thymectomy can achieve favorable prognosis especially in early-onset generalized MG patients with seropositive acetylcholine receptor antibody. However, poor outcomes, including worsening or relapse of MG, postoperative myasthenic crisis and even post-thymectomy MG, are also observed in certain scenarios. The responses to thymectomy may be associated with the general characteristics of patients, disease conditions of MG, autoantibody profiles, native or ectopic thymic pathologies, surgical-related factors, pharmacotherapy and other adjuvant modalities, and the presence of comorbidities and complications. However, in addition to these variations among individuals, pathological remnants and the abnormal immunological milieu and responses potentially represent major mechanisms that underlie the detrimental neurological outcomes after thymectomy. We underscore these plausible risk factors and discuss the immunological implications therein, which may be conducive to better managing the indications for thymectomy, to avoiding modifiable risk factors of poor responses and adverse outcomes, and to developing post-thymectomy preventive and therapeutic strategies for MG.

Clinical Predictors of Prolonged Hospital Stay in Patients with Myasthenia Gravis: A Study Using Machine Learning Algorithms

Myasthenia gravis (MG) is an autoimmune disorder that causes muscle weakness. Although the management is well established, some patients are refractory and require prolonged hospitalization. Our study is aimed to identify the important factors that predict the duration of hospitalization in patients with MG by using machine learning methods. A total of 21 factors were chosen for machine learning analyses. We retrospectively reviewed the data of patients with MG who were admitted to hospital. Five machine learning methods, including stochastic gradient boosting (SGB), least absolute shrinkage and selection operator (Lasso), ridge regression (Ridge), eXtreme gradient boosting (XGboost), and gradient boosting with categorical features support (Catboost), were used to construct models for identify the important factors affecting the duration of hospital stay. A total of 232 data points of 204 hospitalized MG patients admitted were enrolled into the study. The MGFA classification, treatment of high-dose intravenous corticosteroid, age at admission, treatment with intravenous immunoglobulins, and thymoma were the top five significant variables affecting prolonged hospitalization. Our findings from machine learning will provide physicians with information to evaluate the potential risk of MG patients having prolonged hospital stay. The use of high-dose corticosteroids is associated with prolonged hospital stay and to be used cautiously in MG patients.

Heterogeneity in myasthenia gravis: considerations for disease management

Introduction: Myasthenia gravis is a rare disease of the neuromuscular junction and a prototype of B cell-driven immunopathology. Pathogenic antibodies target post-synaptic transmembrane proteins, most commonly the nicotinic acetylcholine receptor and the muscle-specific tyrosine kinase, inducing end-plate alterations and neuromuscular transmission impairment. Several clinical subtypes are distinct on the basis of associated antibodies, age at symptom onset, thymus pathology, genetic factors, and weakness distribution. These subtypes have distinct pathogenesis that can account for different responses to treatment. Conventional therapy is based on the use of symptomatic agents, steroids, immunosuppressants and thymectomy. Of late, biologics have emerged as effective therapeutic options.Areas covered: In this review, we will discuss the management of myasthenia gravis in relation to its phenotypic and biological heterogeneity, in the light of recent advances in the disease immunopathology, new diagnostic tools, and results of clinical trialsExpert opinion: Clinical management is shaped on serological subtype, and patient age at onset, lifestyle and comorbidities, balancing therapeutic needs and safety. Although reliable biomarkers predictive of clinical and biologic outcome are still lacking, recent developments promise a more effective and safe treatment. Disease subtyping according to serological testing and immunopathology is crucial to the appropriateness of clinical management.

Safety and effectiveness of eculizumab in Japanese patients with generalized myasthenia gravis: interim analysis of post-marketing surveillance

BACKGROUND

Eculizumab, a humanized monoclonal antibody targeted to terminal complement protein C5, is approved in Japan for treatment of patients with anti-acetylcholine receptor antibody-positive (AChR+) generalized myasthenia gravis (gMG) whose symptoms are difficult to control with high-dose intravenous immunoglobulin (IVIg) therapy or plasmapheresis.

METHODS

This interim analysis of mandatory post-marketing surveillance in Japan assessed the safety and effectiveness of eculizumab at 26 weeks after treatment initiation in patients with AChR+ gMG.

RESULTS

Data were available for 40 adult patients in Japan [62.5% (25/40) female; mean age at eculizumab initiation, 51.0 years]. Fifteen patients had a history of thymoma. Six patients were excluded from the effectiveness analysis set due to participation in the open-label extension part of the phase III, randomized, double-blind, placebo-controlled REGAIN study [ClinicalTrials.gov identifier: NCT02301624]. After 26 weeks' follow up, 32 patients (80%) were continuing eculizumab treatment. Adverse drug reactions were reported by seven patients [most frequently headache (n = 3)]. One death was reported during eculizumab treatment (relationship unclear as determined by the treating physician) and there was one death 45 days after the last dose (considered unrelated). No meningococcal infections were reported. Mean (standard deviation) changes from baseline in Myasthenia Gravis-Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) scores were -3.7 (2.61) (n = 27) and -5.6 (3.50) (n = 26), respectively, at 12 weeks, and -4.3 (2.72) (n = 26) and -5.6 (4.02) (n = 24), respectively, at 26 weeks. Improvements in MG-ADL and QMG scores were generally similar in patients with/without a history of thymoma. Frequency of IVIg use decreased following eculizumab initiation.

CONCLUSION

In a real-world setting, eculizumab was effective and well tolerated for the treatment of AChR+ gMG in adult Japanese patients whose disease was refractory to IVIg or plasmapheresis. These findings are consistent with the efficacy and safety results from the global phase III REGAIN study of eculizumab.

Immunopathology of Autoimmune Myasthenia Gravis: Implications for Improved Testing Algorithms and Treatment Strategies

Myasthenia gravis (MG) is a heterogeneous condition, characterized by autoantibodies (Abs) that target functionally important structures within neuromuscular junctions (NMJ), thus affecting nerve-to-muscle transmission. MG patients are more often now subgrouped based on the profile of serum autoantibodies, which segregate with clinical presentation, immunopathology, and their response to therapies. The serological testing plays an essential role in confirming MG diagnosis and guiding disease management, although a small percentage of MG patients remain negative for antibodies. With the advancements in new highly effective pathophysiologically-specific immunotherapeutic options, it has become increasingly important to identify the specific Abs responsible for the pathogenicity in individual MG patients. There are several new assays and protocols being developed for the improved detection of Abs in MG patients. This review focuses on the divergent immunopathological mechanisms in MG, and discusses their relevance to improved diagnostic and treatment. We propose a comprehensive "reflex testing," algorithm for the presence of MG autoantibodies, and foresee that in the near future, the convenience and specificity of novel assays will permit the clinicians to consider them into routine systematic testing, thus stimulating laboratories to make these tests available. Moreover, adopting treatment driven testing algorithms will be crucial to identify subgroups of patients potentially benefiting from novel immunotherapies for MG.

Suitable indications of eculizumab for patients with refractory generalized myasthenia gravis

Background:

Eculizumab is a humanized monoclonal antibody that targets complement protein C5 and inhibits terminal complement-mediated damage at the neuromuscular junction. Recently, the REGAIN study showed that eculizumab was effective and well tolerated in patients with anti-acetylcholine receptor antibody-positive refractory generalized myasthenia gravis (gMG). However, there is no consensus regarding which kind of patients with gMG are selected to preferentially receive eculizumab.

Methods:

Between January and December 2018, we followed 1388 patients with MG at seven hospitals located in Tokyo and Chiba. We evaluated the clinical features of MG and the patients’ quality of life. Clinical status and severity were determined by the recommendations of the Myasthenia Gravis Foundation of America.

Results:

Of 1388 patients with MG, 12 (0.9%) patients received eculizumab. A total of 11 patients who were anti-acetylcholine receptor antibody-positive with refractory gMG (M:F = 3:8) completed the 26-week treatment with eculizumab. The disease subtypes represented included five cases of early onset MG, one of late-onset MG, and five of thymoma-associated MG. Overall, seven patients had experienced myasthenic crisis. The mean quantitative MG score ranged from 18.6 at baseline to 9.1 at week 26 (p = 0.008). Similarly, the mean MG activities of daily living score ranged from 10.8 at baseline to 4.2 at week 26 (p = 0.002). There were marked improvements in all patients’ quality of life status. Overall, seven patients were able to reduce the dose of prednisolone at week 26. All but one patient did not require additional rescue treatment. Overall, one patient with early onset MG could not continue the eculizumab treatment due to nausea and vertigo.

Conclusion:

We demonstrate that eculizumab provided remarkable benefits for refractory gMG in practical real-world experience as well as in the REGAIN study. Patients with refractory gMG with myasthenia crisis and thymoma-associated MG are suitable for eculizumab administration.

Lower number of plasma exchange sessions and glomerular filtration rate decline are associated with second relapses in patients with myasthenia gravis

The aims were to determine the impact of dysphagia and glomerular filtration rate (GFR) in the prediction of myasthenia relapse and analyse whether different number of plasma exchange sessions could prolong the time before future relapse.This was a retrospective, longitudinal follow-up study with 60 enrolled patients. The patients were followed-up for a total of 50 months.Patients without relapses had significantly higher GFR and higher number of plasma exchange sessions when compared to patients with relapses. Mean time before next myasthenia relapse was significantly longer in patients with GFR ≥ 60 mL/min. Time before next and number of following myasthenia relapses were significantly higher in patients with symptoms of dysphagia.Decline in GFR levels is strongly associated with the presence of dysphagia and independently impacts the onset of myasthenia relapses. Timely initiation of plasmapheresis therapy and adequate hydration of patients with prolonged dysphagia should be one of the treatment goals for clinicians treating this disease.

Clinical predictors for the prognosis of myasthenia gravis

Background

Clinical predictors for myasthenia gravis relapse and ocular myasthenia gravis secondary generalization during the first two years after disease onset remain incompletely identified. This study attempts to investigate the clinical predictors for the prognosis of Myasthenia Gravis.

Methods

Eighty three patients with myasthenia gravis were concluded in this study. Baseline characteristics were analyzed as predictors.

Results

Relapse of myasthenia gravis developed in 26 patients (34%). Generalization developed in 34 ocular myasthenia gravis patients (85%). Other autoimmune diseases were observed more commonly in relapsed myasthenia gravis (P = 0.012). Second generalization group contained more late onset patients (P = 0.021). Ocular myasthenia gravis patients with thymus hyperplasia progressed more rapidly than those with other thymus pathology (P = 0.027). Single onset symptom of ocular myasthenia gravis such as ptosis or diplopia predicted early progression than concurrence of ptosis and diplopia (P = 0.027). Treatment effect including glucocorticoid, pyridostigmine, thymectomy, IVIG, immunosuppressive drugs did not show significant difference between the relapsed and non-relapsed groups. The treatment outcome also showed no difference between the single OMG and second generalized groups.

Conclusions

Occurrence of associated autoimmune disease can serve as a potential predictor for myasthenia gravis relapse. Either ptosis or diplopia, as well as thymic hyperplasia can predict generalization in the first six months.

β2-Adrenergic receptor gene polymorphisms in the relapse of myasthenia gravis with thymus abnormality

BACKGROUND

The role of β2-adrenergic receptor (β2-AR) in the relapse of myasthenia gravis (MG) associated with thymus abnormality has not been fully identified.

METHODS

Using polymerase chain reaction and gene sequencing method, we investigated the relationship of β2-AR gene polymorphisms with different thymus pathology in MG patients. The role of β2-AR gene polymorphisms in the relapse of MG was further investigated.

RESULTS

Age of onset (p = 0.034), the onset symptom of ocular MG (OMG; p = 0.023), the first symptom of OMG second generalization (p = 0.040) were different in MG with thymoma from those in MG with normal thymus or thymus hyperplasia. Gene polymorphisms of β2-AR on positions 16 and 27 showed no significant difference between relapsed and non-relapsed MG patients with thymus abnormality (thymus hyperplasia: position 16, p = 0.792; position 27, p = 0.664; thymoma: position 16, p = 0.226; position 27, p = 0.615). However, genotypes distribution on position 27 among MG patients with three thymus histology was significantly different (χ² = 8.153, p = 0.041). Furthermore, glucocorticoid can decrease relapse of MG with thymus hyperplasia (p = 0.021).

CONCLUSIONS

MG patients with thymus abnormality differ from MG patients with normal thymus in age of onset, the onset symptom of OMG and the first symptom of OMG second generalization. β2-AR gene polymorphisms had no relationship with the relapse of MG with thymus abnormality. Gene polymorphism of β2-AR on position 27 was associated with different thymus histology of MG. Glucocorticoid was able to reduce the risk of relapse of MG with thymus hyperplasia.

Slug overexpression is associated with poor prognosis in thymoma patients

Slug, a member of the Snail family of transcriptional factors, is a newly identified suppressive transcriptional factor of E-cadherin. The present study investigated the expression pattern of Slug in thymomas to evaluate its clinical significance. Immunohistochemistry was used to investigate the expression pattern of the Slug protein in archived tissue sections from 100 thymoma and 60 histologically normal thymus tissue samples. The associations between Slug expression and clinicopathological factors, such as prognosis, were analyzed. Positive expression of Slug was detected in a greater proportion of thymoma samples [51/100 (51%) patients, P<0.001] compared with normal thymus tissues [9/60 (15%) cases]. Of the 100 patients with thymoma, 42 (42%) displayed high levels of Slug expression (high-level group) and 58 (58%) displayed low levels of Slug expression (low-level group). The 10-year survival rate was improved for patients in the low-level group when compared with those in the high-level group (P=0.002). A multivariate analysis using the Cox proportional hazards regression model demonstrated that Slug overexpression was not an independent prognostic factor. In conclusion, the present study demonstrated that Slug overexpression was associated with poor prognosis in patients with thymoma. Therefore, Slug may be a potential diagnostic biomarker and a predictor of poor prognosis in thymoma patients.