Responsiveness to low-dose rituximab in refractory generalized myasthenia gravis

Therapeutic potential of natural killer cells in neuroimmunological diseases

Natural killer (NK) cells, a major component of the innate immune system, have prominent immunoregulatory, antitumor proliferation, and antiviral activities. NK cells act as a double-edged sword with therapeutic potential in neurological autoimmunity. Emerging evidence has identified NK cells are involved in the development and progression of neuroimmunological diseases such as multiple sclerosis, neuromyelitis optica spectrum disorders, autoimmune encephalitis, Guillain-Barré Syndrome, chronic inflammatory demyelinating polyneuropathy, myasthenia gravis, and idiopathic inflammatory myopathy. However, the regulatory mechanisms and functional roles of NK cells are highly variable in different clinical states of neuroimmunological diseases and need to be further determined. In this review, we summarize the evidence for the heterogenic involvement of NK cells in the above conditions. Further, we describe cutting-edge NK-cell-based immunotherapy for neuroimmunological diseases in preclinical and clinical development and highlight challenges that must be overcome to fully realize the therapeutic potential of NK cells.

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

Introduction

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

Methods

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

Results

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

Discussion

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

Long-Term Efficacy and Safety of Low-Dose Rituximab in Patients with Refractory Myasthenia Gravis

INTRODUCTION

Rituximab is a monoclonal chimeric antibody against CD20+ B cells. We aimed to assess the long-term efficacy and safety of CD20+ B cell-guided treatment with low-dose rituximab in refractory myasthenia gravis patients.

METHODS

Patients with refractory myasthenia gravis treated with rituximab for more than 2 years were included. Rituximab was administered when CD20+ B cells were greater than 1%. We analysed the efficacy of rituximab, treatment interval, side effects, prognosis, and treatment course.

RESULTS

A total of 22 patients were included. All patients received 2-12 doses of rituximab, and the median follow-up time was 48.5 months. The scores of the Myasthenia Gravis Activities of Daily Living and Myasthenia Gravis Composite were significantly lower than those at baseline (p < 0.05). MGFA-PIS was significantly improved in 21 (95.45%) patients and 14 (63.64%) patients have reached MGFA-PIS minimal manifestations. The average daily dose of prednisone and pyridostigmine bromide and the proportion of immunosuppressants were significantly lower (p < 0.05). Seven patients suffered from 14 worsenings. Eight patients terminated rituximab due to good efficacy. Most patients tolerated rituximab well, although 1 patient had opportunistic infection and hypogammaglobulinemia, 1 patient had an intracranial mass.

CONCLUSION

Long-term CD20+ B-cell-guided low-dose rituximab showed good efficacy and tolerance in patients with refractory myasthenia gravis.

Novel Immunotherapies for Myasthenia Gravis

Myasthenia gravis (MG), a prototype autoimmune neurological disease, had its therapy centred on corticosteroids, non-steroidal broad-spectrum immunotherapy and cholinesterase inhibitors for several decades. Treatment-refractory MG and long-term toxicities of the medications have been major concerns with the conventional therapies. Advances in the immunology and pathogenesis of MG have ushered in an era of newer therapies which are more specific and efficacious. Complement inhibitors and neonatal Fc receptor blockers target disease-specific pathogenic mechanisms linked to myasthenia and have proven their efficacy in pivotal clinical studies. B cell-depleting agents, specifically rituximab, have also emerged as useful for the treatment of severe MG. Many more biologicals are in the pipeline and in diverse stages of development. This review discusses the evidence for the novel therapies and the specific issues related to their clinical use.

A single low-dose rituximab infusion in severe chronic refractory myasthenia gravis in resource-limited settings

The benefits of multi-dose rituximab cycles in patients with refractory anti-muscle-specific kinase antibody myasthenia gravis (MuSK+MG) are well reported, although less consistently in anti-acetylcholine receptor antibody MG (AChR+MG). Responsivity data to single low-dose rituximab infusions for refractory autoimmune myasthenia, are limited. Here, observational outcomes using MG grading scores and prednisone doses, before and after at least six months of a single-dose infusion of rituximab, were audited in previously treatment-refractory MG patients in a resource-limited setting. Seventeen moderately-severe to severely symptomatic MG patients received single low-dose rituximab infusions (median 500-600 mg) after a median MG duration of 6 years; 13 individuals responded including 5/5 MuSK+MG, 7/10 AChR+MG and 1/2 double seronegative MG. Three (60%) MuSK+MG and three (30%) AChR+MG achieved persistent asymptomatic status. Although more MuSK+MG vs AChR+MG cases stopped prednisone (80% vs 20%, respectively), the prednisone doses in the AChR+MG group was significantly reduced ≥30% (p = 0.008) due to improved MG composite scores (p = 0.016) and with durable benefit (median 12 months). There were no differences between responders and non-responders in MG duration and age at infusion. These results suggest that a single low-dose rituximab infusion is worth trying in refractory MG, including AChR+MG patients, as some patients showed good and durable responses. These results are particularly relevant to resource-limited settings.

Long-Term Remission With Low-Dose Rituximab in Myasthenia Gravis: A Retrospective Study

OBJETIVE

Rituximab (RTX) is a therapeutic option, for patients with myasthenia gravis (MG) not responding to conventional immunosuppressive treatment. In this cohort, we evaluated long-term efficacy of RTX in the treatment of refractory generalized MG.

METHODS

A retrospective study was performed in adult patients with refractory generalized MG and at least 24 months of follow-up, between January/2015 and October/2021. The Myasthenia Gravis Status and Treatment Intensity Score was used to assess outcomes, and CD19/CD20+ B-cell counts were monitored.

RESULTS

Sixteen patients with MG (8 antiacetylcholine receptor+ and 8 muscle-specific antikinase+; mean age 45.5 ± 16.2 years) treated with low-dose RTX protocols were included. CD19/CD20 levels remained undetectable 12 months after induction, and no new relapses were observed during follow-up.

CONCLUSIONS

Low-dose RTX infusions were sufficient to achieve undetectable CD19/20 cell counts and sustained clinical remission. In low and middle-income countries, the impact of low-dose RTX therapy represents a paradigm shift in decision-making for long-term treatment.

Rituximab in Myasthenia Gravis- Experience from a Low- and Middle-Income Country (LMIC) Setting

BACKGROUND

Myasthenia gravis (MG) is an immune-mediated disorder of the neuromuscular junction. About 10% are refractory to immunosuppressive therapy.

AIMS

To analyze the response of patients with generalized MG to rituximab.

METHODS AND MATERIALS

A retrospective review of patients with MG who received rituximab was carried out (n = 13, M:F = 6:7, mean age: 44.84 ± 15.73 years). Myasthenia Gravis Foundation of America (MGFA), MGFA post-intervention status (MGFA-PIS), and Myasthenia Gravis Status and Treatment Intensity (MGSTI) were assessed before and after rituximab.

RESULTS

The duration of MG was 104.07 ± 92.25 months. Before rituximab, the MGFA was IIA/IIB/IIIA/IIIB/IVB/V in 1/1/2/6/2/1 patients and MGSTI was four in eight patients and six in three patients. The mean duration of follow up was 20.92 ± 14.06 months (range, 4 to 42 months). Dose reduction or discontinuation of cholinesterase inhibitors could be achieved 12 patients. Complete stable remission (CSR) and pharmacologic remission (PR) were achieved in one and four patients respectively and five patients had minimal manifestations. Most patients attained level 0, 1 or 2 MGSTI at last follow up. No rituximab infusion-related adverse events were noted. Three patients had exacerbation of MG between one to five weeks after rituximab administration. Three patients died, one each due to a cardiac event unrelated to MG or treatment, complications related to myasthenic crisis, and coronavirus disease.

CONCLUSIONS

Rituximab was effective in bringing about remission in MG and can be considered as a first-line agent. However, it has to be administered under close supervision as some patients develop exacerbation of MG akin to steroid-induced worsening.

The impact of Rituximab administered before transplantation in patients undergoing allogeneic hematopoietic stem cell transplantation: A real-world study

Rituximab is used to eliminate B cells as a chimeric monoclonal antibody directed against CD20, a B-cell antigen expressed on B cells. To explore the impact of rituximab administered before transplantation, we implemented a retrospective, monocentric study and utilized real-world data collected at our center between January 2018 and December 2020, and then followed until December 2021. Based on whether a dose of 375mg/m2 rituximab was used at least once within two weeks before transplantation, patients undergoing allo-HSCT were classified into two groups: rituximab (N=176) and non-rituximab (N=344) group. Amongst all the patients, the application of rituximab decreased EBV reactivation (P&lt;0.01) and rituximab was an independent factor in the prevention of EBV reactivation by both univariate and multivariate analyses (HR 0.56, 95%CI 0.33-0.97, P=0.04). In AML patients, there were significant differences in the cumulative incidence of aGVHD between the two groups (P=0.04). Our data showed that rituximab was association with a decreased incidence of aGVHD in AML patients according to both univariate and multivariate analyses. There was no difference between the two groups in other sets of populations. Thus, our study indicated that rituximab administered before transplantation may help prevent EBV reactivation in all allo-HSCT patients, as well as prevent aGVHD in AML patients after allo-HSCT.

Current Treatment of Myasthenia Gravis

Myasthenia gravis (MG) is the most extensively studied antibody-mediated disease in humans. Substantial progress has been made in the treatment of MG in the last century, resulting in a change of its natural course from a disease with poor prognosis with a high mortality rate in the early 20th century to a treatable condition with a large proportion of patients attaining very good disease control. This review summarizes the current treatment options for MG, including non-immunosuppressive and immunosuppressive treatments, as well as thymectomy and targeted immunomodulatory drugs.

Individualized regimen of low-dose rituximab monotherapy for new-onset AChR-positive generalized myasthenia gravis

BACKGROUND

Generalized AChR-MG is an archetype of B cell-mediated autoimmune disorders, and use of biologic agent rituximab (RTX) for B cell depletion is generally limited to immunosuppressive therapy-refractory cases. However, benefit of RTX monotherapy and individualized regimen with optimal dosage in early stage of new-onset generalized AChR-MG still remains to be elucidated. In this retrospective study, we explore the efficacy and safety of personalized regimen of 100 mg low-dose rituximab monotherapy in treating new-onset generalized AChR-MG.

METHODS

Thirteen new-onset generalized AChR-MG patients were enrolled for the study, initiating RTX treatment from November 2017 to August 2020. The individualized low-dose RTX monotherapy protocol consisted of 100 mg induction treatment weekly with no more than three circles, followed by reinfusion (100 mg once) sequentially according to whether achieving primary endpoint and peripheral CD19 + B-cell repopulation ≥ 1% of total lymphocytes at each visit (every 3 months). Outcome measures included MGFA-PIS Minimal Manifestation (MM) or better status (primary endpoint), changes in QMG, MMT, MG-ADL and MGQOL-15 scores (secondary endpoint), as well as cholinesterase inhibitors dosage.

RESULTS

All 13 patients achieved the primary endpoint in parallel with significant improvement of QMG, MMT, MG-ADL MGQOL-15 scores, and reduction of cholinesterase inhibitors dose. A total of 52 visits were performed during follow-up, and only 10 assessments presenting peripheral CD19 + B-cell repopulation (≥ 1%) without "MM or better status" were followed by RTX reinfusions (100 mg once) for clinical remission. The total dosage of RTX was only 346.15 ± 96.74 mg (including 269.23 ± 63.04 mg for induction and 76.92 ± 59.91 mg for reinfusion), which seemed to be much lower than those dosages used in new-onset generalized AChR-MG as described previously. Moreover, compared with patients without thymoma, thymectomy markedly delayed initiation of RTX for patients with thymoma (log-rank test, p = 0.0002), but the delaying treatments showed no influence on the time for achieving primary outcome (log-rank test, p = 0.2517).

CONCLUSION

Our study firstly showed that individualized regimen of low-dose RTX monotherapy is effective and safe for early treatment of new-onset generalized AChR-MG, and practicable for directing RTX reinfusion and withdrawal. Moreover, the monotherapy protocol was also indicated to be extensively applicable in both new-onset AChR-MG with thymoma (thymectomy) and without thymoma.

Utilization of MG-ADL in myasthenia gravis clinical research and care

The Myasthenia Gravis Activities of Living (MG‐ADL) scale is an 8‐item patient‐reported scale that measures myasthenia gravis (MG) symptoms and functional status. The objective of the current review is to summarize the psychometric properties of the MG‐ADL and published evidence of MG‐ADL use. A targeted literature review for published studies of the MG‐ADL was conducted using a database and gray literature search. A total of 48 publications and 35 clinical trials were included. Studies indicated that the MG‐ADL is a reliable and valid measure that has been used as an outcome in clinical trials and observational studies to measure MG symptoms and response to treatment. While most often used as a secondary endpoint in clinical trials, its use as a primary endpoint has increased in recent years. The most common MG‐ADL endpoint is change in MG‐ADL score from baseline, although there has been an increase in the analysis of a responder threshold using the MG‐ADL. A new concept of minimal symptom expression (MSE) has emerged more recently. Duration of treatment effect is another important construct that is being increasingly evaluated using the MG‐ADL. The use of the MG‐ADL as a primary endpoint in clinical trials and in responder threshold analyses to indicate treatment improvement has increased in recent years. MSE using the MG‐ADL shows promise in helping to determine success of treatment and may be the aspirational goal of MG treatment for the future once validated, particularly given the evolving treatment landscape in MG.

Rituximab in the Management of Refractory Myasthenia Gravis and Variability of Its Efficacy in Anti-MuSK Positive and Anti-AChR Positive Myasthenia Gravis

Myasthenia gravis affects the neuromuscular junction of the skeletal muscles. It results in muscle weakness involving skeletal muscles (diaphragm, extraocular muscles) and myasthenic crisis. Treatment options for myasthenia gravis management have expanded, including azathioprine, corticosteroids, plasma exchange, and tacrolimus. Unfortunately, a few cases of myasthenia gravis don't respond to conventional treatment modalities. Monoclonal antibodies, rituximab (RTX), are novel treatments that have garnered interest as of late due to their efficacy within the patient population presented with refractory form myasthenia gravis. This review aims to showcase how RTX is an effective treatment within different forms of myasthenia gravis. A limited review was performed using databases that include PubMed and Google Scholar. The following keywords were used: "myasthenia gravis," "rituximab," "monoclonal antibody," "anti-AChR antibody," and "refractory myasthenia." The review focused on case reports, human studies, or research surveys based on the inclusion criteria of human studies involving participants more than 18 years of age and published in English literature. Out of 69 articles, 14 were duplicates, and 29 were relevant and met the inclusion criteria. The findings from the study demonstrate that patients with refractory myasthenia gravis responded well to RTX treatment. Furthermore, RTX has been shown to decrease corticosteroid dependence, induce sustained remission, and have a favorable response to anti-MuSK antibody positive myasthenia gravis compared to anti-AChR antibody positive myasthenia gravis. This literature review suggests that patients with refractory myasthenia gravis can benefit from rituximab; however, it has a variable response in different forms of myasthenia gravis.

Effectiveness and Safety of Rituximab for Refractory Myasthenia Gravis: A Systematic Review and Single-Arm Meta-Analysis

Background and Objective: Myasthenia gravis (MG) is an autoimmune neuromuscular disease. Nearly 10-30% of patients with MG are refractory to conventional therapy. Rituximab (RTX), a monoclonal antibody targeting CD20, is increasingly used in autoimmune disorders. We performed a systematic review and meta-analysis to evaluate the effectiveness and safety of RTX for refractory MG. Methods: Studies published between January 1, 2000 and January 17, 2021 were searched in PubMed, EMBASE, Cochrane Library, and ClincalTrails.gov. Primary outcomes included proportion of patients achieving minimal manifestation status (MMS) or better and quantitative MG (QMG) score change from baseline. Secondary outcomes were glucocorticoids (GC) doses change from baseline and proportion of patients discontinuing oral immunosuppressants. Results: A total of 24 studies involving 417 patients were included in the meta-analysis. An overall 64% (95% confidence interval, 49-77%) of patients achieved MMS or better. The estimated reduction of QMG score was 1.55 (95% confidence interval, 0.88-2.22). The mean reduction of GC doses was 1.46 (95% confidence interval, 1.10-1.82). The proportion of patients discontinuing oral immunosuppressants was 81% (95% confidence interval, 66-93%). Subgroup analyses showed that the proportion of patients achieving MMS or better and discontinuing oral immunosuppressants was higher in MuSK-MG group than those in AChR-MG group. Improvement was more pronounced in patients with mild to moderate MG compared to those with severe MG. Moreover, the efficacy appeared to be independent of the dose of RTX. 19.6% of patients experienced adverse events, most of which were mild to moderate. Only one patient developed progressive multifocal leukoencephalopathy. Conclusions: RTX can alleviate the symptom of weakness, decrease QMG score and reduce the doses of steroids and non-steroid immunosuppressive agents in refractory MG. It is well-tolerated with few severe adverse events. Randomized controlled trials are urgently needed to study the efficacy of RTX in treating refractory MG and to identify the characteristics of patients who might respond well to RTX.

Serum levels and genetic variation of IL-35 are associated with multiple sclerosis: a population-based case-control study

This study aimed to investigate the association between serum levels and polymorphic variants of IL-35 with susceptibility, clinical features, and disease severity in multiple sclerosis (MS) patients.This case-control study recruited 186 MS patients and 195 sex- and age-matched healthy controls. Serum levels and polymorphic variants of IL-35 were determined by ELISA and restriction fragment length polymorphism (RFLP)-PCR or high resolution melting (HRM) analysis methods, respectively. In addition, by in silico analysis, we evaluated the location and function of the polymorphism.Serum levels of IL-35 were significantly lower in the patients than those of healthy controls (49.3 ± 3.7 vs. 69.5 ± 7.8, p = 0.009). EBI3 rs4740 polymorphism of IL-35 was associated with 2.2-fold increased risk of MS susceptibility (95% CI, 1.3-3.9, p = 0.005). However, there were no differences in the genotype distribution and allele frequencies of IL-35 rs568408 between the patients and controls (p > 0.05). In silico results showed that variation in IL-12A and EBI3 may affect on protein pathways of the cells and different components of the immune system such as NF-κB and INF-γ.The results show that IL-35 polymorphisms might be a genetic risk factor for the development of MS.

Eculizumab in refractory generalized myasthenia gravis previously treated with rituximab: subgroup analysis of REGAIN and its extension study

INTRODUCTION/AIMS

Individuals with refractory generalized myasthenia gravis (gMG) who have a history of rituximab use and experience persistent symptoms represent a population with unmet treatment needs. The aim of this analysis was to evaluate the efficacy and safety of eculizumab in patients with refractory anti-acetylcholine receptor antibody-positive (AChR⁺ ) gMG previously treated with rituximab.

METHODS

This post hoc subgroup analysis of the phase 3 REGAIN study (NCT01997229) and its open-label extension (OLE; NCT02301624) compared baseline characteristics, safety, and response to eculizumab in participants who had previously received rituximab with those who had not. Rituximab use was not permitted within the 6 months before screening or during REGAIN/OLE.

RESULTS

Of 125 REGAIN participants, 14 had received rituximab previously (7 received placebo and 7 received eculizumab). In the previous-rituximab group, 57% had used at least four other immunosuppressants compared with 16% in the no-previous-rituximab group. Myasthenia Gravis Activities of Daily Living total scores from eculizumab baseline to week 130 of eculizumab treatment improved in both the previous-rituximab and no-previous-rituximab groups (least-squares mean -4.4, standard error of the mean [SEM] 1.0 [n = 9] and least-squares mean -4.6, SEM 0.3 [n = 67], respectively; difference = 0.2, 95% confidence interval -1.88 to 2.22). In addition, in both groups, most patients who were treated with eculizumab for 130 weeks achieved a Myasthenia Gravis Foundation of America post-intervention status of minimal manifestations (66.7% and 65.0%, respectively). The eculizumab safety profile was similar between groups and consistent with its established profile.

DISCUSSION

Eculizumab is an effective therapy for patients with refractory AChR⁺ gMG, irrespective of whether they had received rituximab treatment previously.

Zytux in Refractory Myasthenia Gravis: A Multicenter, Open-Labeled, Clinical Trial Study of Effectiveness and Safety of a Rituximab Biosimilar

Objectives: Myasthenia gravis (MG) is an immune-mediated neuromuscular disorder responsive to immunomodulatory treatments. 10-20% of MGs are not responsive to conventional first-line therapies. Here, we sought to investigate the efficacy and safety of rituximab therapy in the treatment of patients with refractory MG. Methods: In a 48-week, multicenter, open-labeled, prospective cohort setting, 34 participants with refractory MG were assigned to receive infusions of Zytux, which is a rituximab biosimilar, according to a validated protocol. Clinical, functional, and quality of life (QoL) measurements were recorded at baseline, and seven further visits using the Myasthenia Gravis Foundation of America (MGFA), Myasthenia Gravis Composite (MGC), Myasthenia Gravis Activities of Daily Living profile (MG-ADL), and Myasthenia Gravis Quality of Life (MGQoL-15) scales. Besides, the post-infusion side effects were systematically assessed throughout the study. Results: The correlation analysis performed by generalized estimating equations analysis represented a significant reduction of MGC, MG-ADL, and MGQoL-15 scores across the trial period. The subgroup analysis based on the patients' clinical status indicated a significant effect for the interaction between time and MGFA subtypes on MG-ADL score, MGC score, and pyridostigmine prednisolone dose, reflecting that the worse clinical condition was associated with a better response to rituximab. Finally, no serious adverse event was documented. Conclusions: Rituximab therapy could improve clinical, functional, and QoL in patients with refractory MG in a safe setting. Further investigations with larger sample size and a more extended follow-up period are warranted to confirm this finding. Clinical Trial Registration: The study was registered by the Iranian Registry of Clinical Trials (IRCT) (Code No: IRCT20150303021315N18).

Short- and Long-Lived Autoantibody-Secreting Cells in Autoimmune Neurological Disorders

As B cells differentiate into antibody-secreting cells (ASCs), short-lived plasmablasts (SLPBs) are produced by a primary extrafollicular response, followed by the generation of memory B cells and long-lived plasma cells (LLPCs) in germinal centers (GCs). Generation of IgG4 antibodies is T helper type 2 (Th2) and IL-4, -13, and -10-driven and can occur parallel to IgE, in response to chronic stimulation by allergens and helminths. Although IgG4 antibodies are non-crosslinking and have limited ability to mobilize complement and cellular cytotoxicity, when self-tolerance is lost, they can disrupt ligand-receptor binding and cause a wide range of autoimmune disorders including neurological autoimmunity. In myasthenia gravis with predominantly IgG4 autoantibodies against muscle-specific kinase (MuSK), it has been observed that one-time CD20⁺ B cell depletion with rituximab commonly leads to long-term remission and a marked reduction in autoantibody titer, pointing to a short-lived nature of autoantibody-secreting cells. This is also observed in other predominantly IgG4 autoantibody-mediated neurological disorders, such as chronic inflammatory demyelinating polyneuropathy and autoimmune encephalitis with autoantibodies against the Ranvier paranode and juxtaparanode, respectively, and extends beyond neurological autoimmunity as well. Although IgG1 autoantibody-mediated neurological disorders can also respond well to rituximab induction therapy in combination with an autoantibody titer drop, remission tends to be less long-lasting and cases where titers are refractory tend to occur more often than in IgG4 autoimmunity. Moreover, presence of GC-like structures in the thymus of myasthenic patients with predominantly IgG1 autoantibodies against the acetylcholine receptor and in ovarian teratomas of autoimmune encephalitis patients with predominantly IgG1 autoantibodies against the N‐methyl‐d‐aspartate receptor (NMDAR) confers increased the ability to generate LLPCs. Here, we review available information on the short-and long-lived nature of ASCs in IgG1 and IgG4 autoantibody-mediated neurological disorders and highlight common mechanisms as well as differences, all of which can inform therapeutic strategies and personalized medical approaches.

Effective Early Treatment of AChR Antibody-Positive Myasthenia Gravis with Rituximab; the Experience from a Neuroimmunology Clinic in a Developing Country

Background

Rituximab is reserved for treating refractory myasthenia gravis (MG) patients. Here we report our experience with rituximab in AChR antibody positive generalized MG (gMG) and impending myasthenic crisis (IMC).

Methods

This retrospective, observational study, conducted at a tertiary care, neuroimmunology clinic, analyzed the data of patients with AChR antibody positive gMG, treated with rituximab between 1st January 2016 and 30th October 2018.

Results

Eleven patients with AChR antibody positive gMG received rituximab. Mean age of the cohort was 50.54 ± 18.71 years with 9 males. Seven out of 11 patients received rituximab in the early stage (<2 years from onset) and had good response to treatment. Four of the 5 patients with IMC improved with rituximab alone. In the 10 patients who regularly followed up, there was a significant difference between the QMG scores at baseline and at 1, 2, 6, 12, and 18 months (P < .0001).

Conclusion

Rituximab appears to be a potentially effective early treatment option for AChR antibody positive generalized MG and impending myasthenic crisis.

Short-term effect of low-dose rituximab on myasthenia gravis with muscle-specific tyrosine kinase antibody

INTRODUCTION/AIMS

The study aims to investigate the short-term efficacy of low-dose rituximab and its effect on immunological biomarker levels in myasthenia gravis (MG) patients with antibodies against muscle-specific tyrosine kinase (MuSK-MG).

METHODS

Twelve MuSK-MG patients were enrolled in this prospective, open-label, self-controlled pilot study. Clinical severity was evaluated at baseline and 6 mo after a single rituximab treatment (600 mg). B lymphocyte subtypes, MuSK antibody titers, together with levels of immunoglobulins, serum B-cell activating factor (BAFF), a proliferation-inducing ligand (APRIL), soluble CD40L, and four exosomal microRNAs were evaluated. A correlation matrix to reveal pairwise relationships among above variables was also generated.

RESULTS

The single rituximab treatment significantly lowered the clinical severity scores and reduced daily dosage of prednisone (P = .032) at 6 mo. MuSK antibody titers decreased (P = .035) without significant changes in immunoglobulin levels. Serum BAFF level increased (P = .010), which negatively correlated with the percentages of B cells in lymphocytes as well as clinical severity. Additionally, serum exosomal miR-151a-3p showed a reduction of 28.1% (P = .031).

DISCUSSION

We confirmed the clinical efficacy of low-dose rituximab in MuSK-MG, accompanied by a decrease in MuSK antibody titers and an increase in serum BAFF. Serum BAFF levels negatively correlated with B-cell counts as well as clinical severity.

Rituximab in Myasthenia Gravis - Where do we stand?

Introduction: Myasthenia gravis (MG) is an antibody-mediated disease with diverse serology and clinical presentation. Currently, MG is managed by untargeted immunomodulatory agents. About 15% patients are refractory to these therapies. Several novel and targeted treatments are on the horizon. Rituximab, a monoclonal antibody, is reported to be highly effective with widespread oof-label usage in MG, particularly in patients with antibody against muscle-specific kinase or refractory disease. However, a recent trial showed negative results. Compared to conventional oral immunosuppressive therapies used in MG, Rituximab has several benefits. Regular hematological monitoring is not required though serious side effects can occur. Current status of Rituximab in MG and newer immunosuppressants is discussed.Areas explored: Biologic features, clinical effectiveness, safety profile, and newer preparations of Rituximab.Expert opinion: Rituximab provides a promising option for management of MG, particularly in patients with muscle-specific kinase antibodies or those with refractory disease. Several knowledge gaps remain due to scarcity of data from randomized controlled studies. Despite lack of regulatory approval Rituximab has found widespread usage in MG. Large, well-designed studies are needed to assess the comparative efficacy of Rituximab and its optimal regimen in MG.

Memory B Cells Predict Relapse in Rituximab-Treated Myasthenia Gravis

Myasthenia gravis can be efficiently treated with rituximab but there is no consensus regarding administration and dose schedules in this indication. No marker has yet been described to predict the clinical relapse of patients. Our objective was to identify the B cell subpopulations predicting clinical relapse in patients suffering from generalized myasthenia gravis and treated with rituximab. Clinical and biological data of 34 patients followed between 2016 and 2019 were prospectively collected every 3 months. Using multiparameter flow cytometry, we assessed the percentage in leucocytes of lymphocytes and several B cell subpopulations measured in residual disease conditions. CD19+ were also measured in non-residual disease conditions. Clinical examinations were performed by neurologists using the Osserman score. Clinical relapse occurred in 14 patients (41%). No patients required ICU or ventilatory assistance. The mean improvement of the Osserman score was 17.18 (3-45) after the first rituximab treatment (p < 0.0001). The mean delay between the first rituximab maintenance cycle and clinical relapse was 386.8 days. At the time of relapse, CD27+ increased (p = 0.0006) with AUC = 0.7654, while CD19+ did not. At a threshold of 0.01%, the sensitivity and specificity of CD19+CD27+ were 75.8% and 72.8%, respectively, and the positive and negative predictive values were 28.0% and 95.6%, respectively. The percentage of memory B cells in whole blood cells can accurately predict clinical relapse in myasthenia gravis patients treated with rituximab. This monitoring allows physicians to tailor rituximab administration and to decrease the number of infusions over time.

Efficacy and safety of different dosages of rituximab for refractory generalized AChR myasthenia gravis: A meta-analysis

BACKGROUND

Rituximab (RTX) is a mouse-human chimeric anti-CD20 monoclonal antibody and has been increasingly used for preventing relapses in myasthenia gravis (MG). However, the appropriate dose for maximizing the beneficial effects in refractory MG with acetylcholine receptor (AChR) autoantibody is a long-standing and critical debating question.

METHODS

We performed a meta-analysis to evaluate the efficacy and safety of the different doses of RTX in 260 refractory AChR-MG patients.

RESULTS

The AChR-MG patients were divided into low or routine RTX dose groups. An overall proportion of 77% (p = 0.000) AChR-MG patients demonstrated improved clinical status as indicated by the Myasthenia Gravis Foundation of America post-intervention scale (MGFA-PIS). There were 77.1% patients showed improved clinical status in lower dose of RTX group (p = 0.000) and 76.8% in routine protocol group (p = 0.000). Although we found there was no significant difference in the proportion of AChR-MG patients with improved clinical status or adverse reactions between the two groups, adverse reactions might be lower in the lower dose RTX group.

CONCLUSION

Most of refractory MG patients with anti-AChR autoantibody were well responsive and tolerated to RTX treatment. Repeated application of lower dose of RTX was effective and might be more appropriate for refractory AChR-MG patients with potential lower side effects.

Treatment of refractory myasthenia gravis by double-filtration plasmapheresis and rituximab: A case series of nine patients and literature review

INTRODUCTION

Myasthenia gravis (MG) is an autoimmune disease mediated by circulating autoantibodies (anti-AchR, anti-MuSK, etc.). More than 20% of myasthenic patients are refractory to conventional treatments (plasma exchange, IVIg, steroids, azathioprine, mycophenolate mofetil). Rituximab (B-lymphocyte-depleting anti-CD20) and apheresis (double-filtration plasmapheresis [DFPP] and immunoadsorption [IA]) are interesting therapeutic alternatives.

METHODS

This monocentric pilot study included nine refractory myasthenic patients (March 2018 to May 2020) treated by DFPP and/or IA associated with rituximab (375 mg/m² ). Clinical responses were assessed using the Myasthenia Gravis Foundation of America (MGFA) score.

RESULTS

Average age of patients was 53 ± 17 years. Gender ratio (M/F) was 3:6. The combination of apheresis and rituximab reduced median MGFA score from IV to II after 12 months of follow-up. Clinical improvement assessed by MGFA score was sustained in the long-term for all patients, during an average follow-up of 14 ± 9 months, allowing them to be self-sufficient and out sick-leave. The median number of apheresis sessions was 7 (5-30). The dose of prednisolone was reduced in two patients from 40 mg/d and 30 mg/d to 7.5 mg/d and 10 mg/d, respectively. It was stopped in a patient who was taking 30 mg/d. No infectious, bleeding, or thrombosis complications were noted.

CONCLUSION

The combination of rituximab and DFPP was effective to treat refractory MG.

Immunotherapy choice and maintenance for generalized myasthenia gravis in China

Aims

To compare long‐term efficacy and safety of immunotherapeutic strategies as maintenance to prevent disease relapses of generalized myasthenia gravis (MG) in real‐world settings.

Methods

This is a retrospective cohort study on generalized MG conducted in seven major neurological centers across China. Eligible participants were patients with generalized MG who were under minimal manifestation status or better. Main outcome measures were probability of patients free of relapses and causes of drug discontinuation.

Results

Among 1064 patients enrolled, the median (interquartile range) age was 50.3 (37.0‐62.5) years and 641 (60.2%) were women. Disease relapse was significantly lower for rituximab (6.1%) compared with all the other monotherapies (hazard ratio [HR] = 0.18, 95% confidence interval [CI] 0.06 to 0.56, P = .0030). As combination therapies, tacrolimus in combination with corticosteroids reduced risk of disease relapses compared with azathioprine with corticosteroids (HR = 0.45, 95% CI 0.25 to 0.81, P = .0077) or mycophenolate mofetil with corticosteroids (HR = 0.32, 95% CI 0.15 to 0.67, P = .0020). Otherwise, lower‐dose corticosteroids or azathioprine as monotherapy significantly increased risk of disease relapses (HR = 2.78, 95% CI 1.94 to 3.99, P < .0001; HR = 2.14, 95% CI 1.42 to 3.23, P = .0003, respectively). The proportion of discontinuation was lowest in patients with rituximab (20.4%) as monotherapy and tacrolimus with corticosteroids (23.6%). Overall, combination treatment of immunosuppressants with corticosteroids had a lower rate of discontinuation compared with corresponding monotherapy (HR = 0.51, 95% CI 0.36 to 0.71, P < .0001).

Conclusions

Rituximab as monotherapy and tacrolimus with corticosteroids displayed better clinical efficacy as well as drug maintenance to prevent disease relapses in patients with generalized MG.

Therapeutic and Immunoregulatory Effects of Tacrolimus in Patients with Refractory Generalized Myasthenia Gravis

OBJECTIVES

The aim of this study wasto investigate the efficacy of tacrolimus treatment in patients with refractory generalized myasthenia gravis (MG) and explore its impact on lymphocytic phenotypes and related cytokines mRNA expression.

METHODS

A total of 24 refractory generalized MG patients were enrolled. Before treatment and at 2, 6, and 12 months after tacrolimus treatment, the therapeutic effect was evaluated by the quantitative MG score of the Myasthenia Gravis Foundation of America (QMG), Manual Muscle Test (MMT), MG-specific Activities of Daily Living (MG-ADL), 15-item Myasthenia Gravis Quality-of-Life Scale (MG-QOL15), and changes of prednisone dosage. Also, we used the flow cytometer for the lymphocytic immunophenotyping and real-time PCR for the qualification of cytokine mRNA in peripheral blood mononuclear cells (PBMCs) at different time points during the treatment.

RESULTS

Significantly decreased QMG, MMT, MG-ADL, and MG-QOL15 were observed at all time points during the tacrolimus treatment. The dosage of prednisone also reduced at the end of the observation period with only 6 adverse events reported. The immunological impact of tacrolimus was revealed by reduced percentages of Tfh, Breg, CD19+BAFF-R+ B cells, and increased percentages of Treg cells as well as down-regulated expression of IL-2, IL-4, IL-10, and IL-13 mRNA levels in PBMCs during the treatment.

CONCLUSION

Our study indicated the clinical efficacy of tacrolimus in patients with refractory generalized MG. The underlying immunoregulatory mechanism of tacrolimus may involve alterations in the phenotypes of peripheral blood lymphocytes and Th1/Th2-related cytokine expression of PBMCs.

Low-dose rituximab lowers serum Exosomal miR-150-5p in AChR-positive refractory myasthenia gravis patients

Two potentially related microRNAs (miRNAs; miR-150-5p and miR-146a-5p) were examined after low-dose rituximab (RTX) treatment in patients with acetylcholine receptor antibody (AChR)-positive refractory myasthenia gravis (MG). In this prospective, open-label, and self-controlled pilot trial, 12 AChR-positive refractory MG patients were administrated a single, low dose of RTX and followed up at six months. Results showed that RTX decreased the serum exosomal miR-150-5p, scores on three clinical indices (MGFA, MMT, ADL), and patients' prednisolone requirement. Additionally, CD19+ and CD27+ B cells decreased, showing a strong correlation with miR-150-5p. In conclusion, low-dose RTX is effective for AChR-positive refractory MG treatment. Furthermore, our data support the role of miR-150-5p as a potential biomarker for MG.

Management Issues in Myasthenia Gravis Patients Living With HIV: A Case Series and Literature Review

South Africa is home to more than seven million people living with human immunodeficiency virus (HIV) and a high prevalence of tuberculosis. Human immunodeficiency virus–infected individuals may develop myasthenia gravis (MG), which raises questions regarding their management. An MG database, with 24 years of observational data, was audited for HIV-infected persons. Case reports of MG in HIV-infected persons were reviewed. We identified 17 persons with MG and HIV infection. All had generalized MG with a mean age at onset of 37.8 years. Eleven had acetylcholine receptor antibody–positive MG; one had antibodies against muscle-specific kinase. Six developed MG prior to HIV infection (mean CD4⁺ 361 cells/mm³); four worsened <6 months of starting antiretrovirals. Eleven developed MG while HIV-infected (mean CD4⁺ 423 cells/mm³); five presented with mild MG; three in MG crisis requiring rescue therapies (intravenous immune globulin or plasma exchange and/or intravenous cyclophosphamide). Two were diagnosed with HIV infection and MG at the same time. Fifteen required maintenance steroid-sparing immune therapies, predominantly azathioprine, or methotrexate. Plasma HIV viral loads remained below detectable levels on antiretrovirals during immunosuppressant treatment. Over the average follow-up of 6 years, 10 achieved minimal manifestation status, and the remainder improved to mild symptoms. Three cases had tuberculosis before MG, but none developed tuberculosis reactivation on immunosuppressive therapy; one used isoniazid prophylaxis. Herpes zoster reactivation during treatment occurred in one. Conclusions include the following: MG in HIV-infected patients should be managed similarly to individuals without HIV infection; half develop moderate–severe MG; MG symptoms may worsen within 6 months of antiretroviral initiation; safety monitoring must include plasma HIV viral load estimation. Isoniazid prophylaxis may not be indicated in all cases.

Rituximab in AChR subtype of myasthenia gravis: systematic review

Myasthenia gravis (MG) is a chronic autoimmune disorder of the neuromuscular junction characterised by an autoantibody against acetylcholine receptor (AChR-Ab), autoantibody against muscle-specific kinase (MuSK-Ab), lipoprotein-related protein 4 or agrin in the postsynaptic membrane at the neuromuscular junction. Many patients are resistant to conventional treatment and effective therapies are needed. Rituximab (RTX) is a monoclonal antibody directed against CD20 antigen on B cells which has been successfully employed in anti-MuSK-Ab+MG, but the efficacy in anti-AChR-Ab+MG is still debated. The purpose of this systematic review was to describe the best evidence for RTX in the acetylcholine receptor subtype. The authors undertook a literature search during the period of 1999-2019 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analys methodology, employing (myasthenia)+(gravis)+(RTX) as search terms. The analysis was confined to studies that include at least five patients with confirmed anti-AChR-Ab+MG. Thirteen studies have been selected, showing a good safety. The data obtained were heterogeneous in terms of posology, administration scheme and patients' evaluation, ranging from a minimum of two to a maximum of three cycles. RTX led to a sustained clinical improvement with prolonged time to relapse, in parallel to a reduction or discontinuation of other immunosuppressive therapies. Treatment with RTX appears to work in some but not all patients with anti-AChR-Ab+MG, but randomised controlled trials are needed. Future studies should take into account the subtype of MG and employ reliable measures of outcome and severity focusing on how to identify patients who may benefit from the treatment. Trial registration number: NCT02110706.

Low-dose rituximab every 6 months for the treatment of acetylcholine receptor-positive refractory generalized myasthenia gravis

INTRODUCTION

In this prospective, open-label study we explore the effectiveness of low-dose rituximab every 6 months in treating refractory generalized myasthenia gravis (GMG).

METHODS

Twelve patients with acetylcholine receptor (AChR)-positive refractory GMG were enrolled for the study. The primary endpoint was the change in quantitative myasthenia gravis (QMG) score from baseline to the study end. Secondary endpoints included changes in manual muscle testing (MMT), MG-Related Activities of Daily Living (MG-ADL), and 15-item Quality-of-Life (MGQOL-15) scores, as well as prednisolone reduction.

RESULTS

MG decreased from 18.25 ± 4.03 to 8.42 ± 3.99 (P = .0001), MMT from 27.50 ± 17.78 to 4.58 ± 4.34 (P = .0001), ADL from 8.50 ± 2.84 to 1.17 ± 1.27 (P < .0001), MGQOL-15 from 37.25 ± 13.78 to 17.50 ± 9.73 (P = .0015), and prednisolone dose from 29.38 ± 11.92 mg/day to 8.86 ± 1.88 mg/day (P ≤ .01).

DISCUSSION

Low-dose rituximab every 6 months is effective in treating refractory GMG patients.

Current pharmacotherapeutic options for myasthenia gravis

Introduction: Novel options for immune-based therapy in myasthenia gravis are improving the therapeutic outlook for patients. Multiple clinical trials on immunomodulation, complement inhibitors, and FcR inhibitors are providing evidence for novel immune-based therapies that promise to improve outcomes in myasthenia patients. These more focused immune treatments are reviewed in this paper.Areas covered: This paper outlines classical treatment for myasthenia gravis and then reviews recent clinical trial evidence for novel immune therapies, particularly complement inhibitors and FcR inhibitors. Further, as immune therapies expand in other areas of medicine, such as oncology, iatrogenic myasthenia is being observed as a complication of some novel treatments.Expert opinion: Exciting new options to help patients with myasthenia gravis are now available or in phase 3 trials based on promising phase 2 results. Manipulation of the immune system can also lead to iatrogenic MG. Although novel treatments can improve care for myasthenia gravis patients, future developments that prevent the production of specific abnormal auto-antibodies are desirable.

Repeated low-dose rituximab treatment based on the assessment of circulating B cells in patients with refractory myasthenia gravis

Background:

The objective of this study was to evaluate the efficacy and safety of repeated low-dose rituximab treatment guided by monitoring circulating CD19+ B cells in patients with refractory myasthenia gravis (MG).

Methods:

Patients with refractory MG who had received rituximab treatment at two teaching hospitals between September 2013 and January 2017 were reviewed retrospectively. The treatment protocol consisted of an induction treatment with low-dose rituximab (375 mg/m² twice with a 2-week interval), followed by retreatment (375 mg/m² once). Retreatment was based on either circulating CD19+ B-cell repopulation or clinical relapse. Outcome measures included the MG Foundation of America (MGFA) clinical classification and postintervention status, prednisolone dose, CD19+ B-cell counts, clinical relapse, and adverse effects.

Results:

Of 17 patients, 11 (65%) achieved the primary endpoint, defined as the minimal manifestation or better status with prednisolone ⩽5 mg/day, after median 7.6 months (range, 2–17 months) following rituximab treatment. Over a median follow up of 24 months (range, 7–49 months), a total of 30 retreatments were undertaken due to clinical relapse without B-cell repopulation (n = 6), on the basis of B-cell repopulation alone (n = 16) and both (n = 8). B-cell recovery appeared to be in parallel with clinical relapse on the group level, although the individual-level association appeared to be modest, with B-cell repopulation observed only at 57% (8/14) of clinical relapses.

Conclusions:

The repeated low-dose rituximab treatment based on the assessment of circulating B-cell depletion could be a cost-effective therapeutic option for refractory MG. Further studies are needed to verify the potentially better cost-effectiveness of low-dose rituximab, and to identify biomarkers that help optimize treatment in MG patients.

Systematic Review of Safety and Efficacy of Rituximab in Treating Immune-Mediated Disorders

Background: During the past years biologic agents (also termed biologicals or biologics) have become a crucial treatment option in immunological diseases. Numerous articles have been published on biologicals, which complicates the decision making process on the use of the most appropriate biologic for a given immune-mediated disease. This systematic review is the first of a series of articles assessing the safety and efficacy of B cell-targeting biologics for the treatment of immune-mediated diseases.

Objective: To evaluate rituximab's safety and efficacy for the treatment of immune-mediated disorders compared to placebo, conventional treatment, or other biologics.

Methods: The PRISMA checklist guided the reporting of the data. We searched the PubMed database between 4 October 2016 and 26 July 2018 concentrating on immune-mediated disorders.

Results: The literature search identified 19,665 articles. After screening titles and abstracts against the inclusion and exclusion criteria and assessing full texts, 105 articles were finally included in a narrative synthesis.

Conclusions: Rituximab is both safe and effective for the treatment of acquired angioedema with C1-inhibitor deficiency, ANCA-associated vasculitis, autoimmune hemolytic anemia, Behçet's disease, bullous pemphigoid, Castleman's disease, cryoglobulinemia, Goodpasture's disease, IgG4-related disease, immune thrombocytopenia, juvenile idiopathic arthritis, relapsing-remitting multiple sclerosis, myasthenia gravis, nephrotic syndrome, neuromyelitis optica, pemphigus, rheumatoid arthritis, spondyloarthropathy, and systemic sclerosis. Conversely, rituximab failed to show an effect for antiphospholipid syndrome, autoimmune hepatitis, IgA nephropathy, inflammatory myositis, primary-progressive multiple sclerosis, systemic lupus erythematosus, and ulcerative colitis. Finally, mixed results were reported for membranous nephropathy, primary Sjögren's syndrome and Graves' disease, therefore warranting better quality trials with larger patient numbers.

Clinical characteristics and long term follow-up of Lambert-Eaton myasthenia syndrome in patients with and without small cell lung cancer

In order to describe the clinical characteristics, treatment response and long-term follow up in Lambert-Eaton myasthenic syndrome (LEMS) patients with and without small cell lung cancer (SCLC) in East China, patients seen in Huashan Hospital from January 1997 to December 2017 were included. Clinical information was collected retrospectively and quantitative MG (QMG) score, manual muscle testing (MMT), activities of daily living (ADL) scale were evaluated when the patients were followed up. Of 50 patients, 23 (46%) were SCLC-LEMS and 20 (40%) were nontumor LEMS (NT-LEMS). The median onset age was 55.5 (18-86) years old and the gender ratio was about 1.8:1. It took less time to make the diagnosis (median time: 6 vs 22.5 months, p = 0.0003) and there were more patients with other paraneoplastic syndromes in SCLC-LEMS group than in NT-LEMS group (8/23 vs 0/20, p = 0.0042). Electrophysiologically, the peroneal compound motor action potential (CMAP) of rest showed difference between SCLC-LEMS and NT-LEMS (0.8 vs 1.6 mV, p = 0.0499). The median survival time of 19 SCLC-LEMS patients since the diagnosis of SCLC was 30 months. According to their survival time, SCLC patients with LEMS showed a more favorable prognosis than those without LEMS. In the time of follow-up, most NT-LEMS showed improvement or obtained status of CSR/PR/MM after immunosuppressive therapy and no significant difference in proportion of achieving CSR/PR/MM was found between SCLC-LEMS and NT-LEMS patients (0/5 vs 6/13, p = 0.114).

Understanding the burden of refractory myasthenia gravis

Myasthenia gravis (MG) is an autoantibody-mediated disease that compromises the acetylcholine receptors or associated structures of the postsynaptic membrane of the neuromuscular junction. This leads to impaired neuromuscular transmission and subsequent fluctuating fatigability and weakness of ocular, bulbar, and limb skeletal muscles. Over the past few decades, there have been significant advances in our understanding of the disease pathophysiology and improvements in prognosis due to intensive care medicine and immunomodulation. Despite this, an estimated 10–20% of patients with MG do not achieve an adequate response, are intolerant to conventional treatment, or require chronic treatment with intravenous immunoglobulins or plasma separation procedures. Such patients are regarded as having MG that is ‘refractory’ to treatment and may represent a distinct clinical subgroup. Because the majority of patients with MG have well-controlled disease, the burden of illness in the minority with refractory disease is poorly understood and may be underestimated. However, clinically these patients are liable to experience extreme fatigue, considerable disability owing to uncontrolled symptoms, and frequent myasthenic crises and hospitalizations. Both acute adverse effects and an increased risk of comorbidity from treatment regimens may contribute to reduced quality of life. As yet, little is known concerning the impact of refractory MG on mental health and health-related quality of life. This review aims to highlight the burden of disease and unmet needs in patients with refractory MG.