Immunosuppressive and monoclonal antibody treatment for myasthenia gravis: A network meta-analysis

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The Efficacy and Safety of Different Targeted Drugs for the Treatment of Generalized Myasthenia Gravis: A Systematic Review and Bayesian Network Meta-analysis

BACKGROUND

The treatment of generalized myasthenia gravis (gMG) has been transformed by the development and approval of new targeted therapies. This analysis aimed to rank and compare the new therapies for gMG using efficacy and safety data from randomized controlled trials (RCTs).

METHODS

We searched PubMed, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov (up to November 2022) for RCTs of targeted drugs for gMG. We used a Bayesian random-effects network meta-analysis (NMA) model and a Markov chain Monte Carlo (MCMC) model for statistical analysis. The primary outcome was the change in quantitative myasthenia gravis score (QMGS) from baseline, while the secondary outcome was the risk ratio (RR) of adverse events (AEs) during treatment. The surface under the cumulative ranking curve (SUCRA) was used to rank these targeted drugs, with higher SUCRA values indicating better efficacy or lower likelihood of AEs.

RESULTS

In total, 13 studies (872 subjects) were included in this analysis evaluating 10 targeted drugs (batoclimab, belimumab, CFZ533, eculizumab, efgartigimod, nipocalimab, rituximab, ravulizumab, rozanolixizumab, and zilucoplan). With regards to the primary outcome, batoclimab [standardized mean difference (SMD), - 1.61; 95% credible interval (CrI), - 2.78, - 0.43] significantly reduced QMGS in patients with gMG when compared with placebo and was ranked as the most efficacious drug. Ranked second and third were eculizumab (SMD, - 0.67; 95% CrI, 1.43, 0.01) and zilucoplan (SMD, - 0.54; 95% CrI, - 1.56, 0.46), respectively. Nipoclimab (SMD, - 0.02; 95% CrI, - 1.04, 1.00) had the worst efficacy and ranked last among all targeted drugs. In our study, except for batoclimab, there was no statistically significant difference in the reduction of patient QMGS for the remaining targeted agents compared with placebo. With regards to the secondary outcomes, only batoclimab (RR, 0.19; 95% CrI, 0, 0.97) led to a significant reduction in the incidence of AEs when compared with the placebo. Belimumab (RR, 0.85; 95% CrI, 0.57, 1.19), CFZ533 (RR, 0.95; 95% CrI, 0.72, 1.25), eculizumab (RR, 0.99; 95% CrI, 0.85, 1.21), and efgartigimod (RR, 0.93; 95% CrI, 0.76, 1.15) also led to a lower incidence of AEs, although these effects were not significantly different from the placebo.

CONCLUSIONS

Batoclimab had the best efficacy and safety for the treatment of gMG and was ranked first out of the 10 targeted drugs included in this study. Eculizumab was ranked second, and nipocalimab had the worst efficacy. With the exception of batoclimab, the incidence of AEs for the remaining drugs was not statistically significantly different from placebo. We note, however, that wide CrIs reflect the uncertainty in this analysis owing to the small number of available studies and low numbers of study participants; moreover, batoclimab had the widest CrI of all drugs in this analysis. More well-designed studies with long-term follow-up are needed to further evaluate and compare the efficacy and safety of these drugs in the future.

Eculizumab in myasthenia gravis: A review

Eculizumab, a monoclonal antibody against complement C5, is a novel therapy to treat refractory myasthenia gravis (MG). The present review was undertaken to study the role of eculizumab in MG. This includes the drug's mechanism, pharmacokinetics, clinical trial findings, tolerability, side effects, safety, dosage, administration, and cost. An English-language search for relevant items was undertaken using Embase and PubMed from 1946 to present. Clinical trial registries/databases and websites were also searched for relevant data. Keywords were eculizumab and MG. The present review found 103 articles after initial screening. Current data support eculizumab as an effective, safe, and tolerable drug in cases of refractory MG. However, its cost can prevent it from being widely accessible to a majority of the general population.

Effectiveness of early glucocorticoids in myasthenia gravis: a retrospective cohort study

Purpose

This study aimed to clarify the effect of early glucocorticoid (GC) application on achieving minimal manifestation (MM) status or better in the treatment of myasthenia gravis (MG) in the early clinical phase.

Methods

A retrospective analysis was performed using data from 336 patients with MG who received GC therapy from January 2015 to September 2022 in the Zhengzhou University Henan Institute of Medical and Pharmaceutical Sciences Myasthenia Gravis Biobank (ZMB). Patients were divided into two groups: the early mono-GC group (treated with GC within 6 months of MG onset) and the delayed mono-GC group.

Results

Kaplan-Meier analysis showed that the early mono-GC group achieved MM status earlier and more frequently than the delayed mono-GC group (log-rank test, p = 0.0082; hazard ratio [HR], 1.66; p = 0.011). The early mono-GC group had a lower maintenance oral GC dose than the delayed mono-GC group. In multivariate Cox regression analysis, early mono-GC (HR, 1.50; p = 0.043), early-onset MG (EOMG) (HR, 1.74; p = 0.034), and ocular MG (OMG) (HR, 1.90; p = 0.007) were associated with MM status or better. In conclusion, early mono-GC, EOMG, and OMG were positive predictors of treatment goals. In EOMG, OMG, and acetylcholine receptor antibody-positive MG (AChR-MG) subgroups, the maintenance oral GC doses in the early mono-GC group were significantly lower than the doses in the delayed mono-GC group (p < 0.05).

Conclusion

Early intervention with GC led to better long-term outcomes and reduced the necessary maintenance dose of oral GC for patients with MG. EOMG and OMG were positive predictors of MM status or better with mono-GC.

Outcomes after robotic thymectomy in nonthymomatous versus thymomatous patients with acetylcholine-receptor-antibody-associated myasthenia gravis

The aim of this study was to investigate the surgical and long-term neurological outcomes of patients with acetylcholine-receptor-antibody-associated myasthenia gravis (AChR-MG) who underwent robotic thymectomy (RATS). We retrospectively analyzed the clinical-pathological data of all patients with AChR-MG who underwent RATS using the DaVinci® Robotic System at the MUMC+ between April 2004 and December 2018. Follow-up data were collected from 60 referring Dutch hospitals. In total, 230 myasthenic patients including 76 patients with a thymoma (33.0%) were enrolled in this study. Mean follow-up time, procedure time and hospitalization were, respectively 65.7 ± 43.1 months, 111±52.5 min and 3.3 ± 2.2 days. Thymomatous patients had significantly more frequently and more severe complications than nonthymomatous patients (18.4% vs. 3.9%, p<0.001). Follow up data was available in 71.7% of the included patients. The Myasthenia Gravis Foundation of America postintervention score showed any kind of improvement of MG-symptoms after RATS in 82.4% of the patients. Complete stable remission (CSR) or pharmacological remission (PR) of MG was observed in 8.4% and 39.4% of the patients, respectively. Mean time till CSR/PR remission after thymectomy was 26.2 ± 29.2 months. No statistical difference was found in remission or improvement in MGFA scale between thymomatous and nonthymomatous patients. RATS is safe and feasible in patients with MG. The majority of the patients (82.4%) improved after thymectomy. CSR and PR were observed in 8.4% and 39.4% of the patients, respectively, with a mean of 26.2 months after thymectomy. Thymomatous patients had more frequently and more severe complications compared to nonthymomatous patients.

Studying the relationship between clinical features and mental health among late-onset myasthenia gravis patients

BACKGROUND

Mental disorders are common comorbidities among individuals with neurological diseases, and the prevalence of depressive and anxiety-related symptoms in newly referred patients at neurology outpatient clinics is high. There have been few studies on the mental health of patients with late-onset myasthenia gravis (MG).

AIM

To examine the relationship between clinical features and the mental health symptoms within late-onset MG patients.

METHODS

A total of 105 patients diagnosed with MG were recruited consecutively from a neuromuscular outpatient clinic between December 2020 and February 2021. Patients were classified into two groups: early-onset MG (age at onset < 50 years, n = 63) and late-onset MG (age at onset ≥ 50 years, n = 42). Social demographic data and information about marital status, education level, clinical symptoms, serum antibody levels, and therapies used were collected for all participants. Participants were also evaluated using the Myasthenia Gravis Composite scale, the Myasthenia Gravis Activities of Daily Living scale, the Myasthenia Gravis Quality of Life 15 (MG-QOL-15) questionnaire, the 17-item version of the Hamilton Depression Rating Scale (HAM-D) and the Hamilton Anxiety Rating Scale (HAM-A). The relationship between clinical features and mental health in late-onset MG patients was examined using multivariate logistic regression analyses.

RESULTS

Late-onset MG patients were more prone to dyspnea, had higher levels of serum anti-acetylcholine receptor antibodies, and higher total scores on the MG-QOL-15, HAM-D, and HAM-A questionnaires, than early-onset MG patients had (P < 0.05). Among those with late-onset MG, female patients had higher total HAM-D and HAM-A scores than male patients had (P < 0.05). High scores on the QOL-15 questionnaire were associated with higher incidences of anxiety and depression, and the association was found to be independent after adjusting for confounding risk factors. In the late-onset subgroup, the areas under the receiver operating characteristic curves for the MG-QOL-15 score-based diagnostic accuracy for anxiety and depression state were 0.816 (P = 0.001) and 0.983 (P < 0.001), respectively.

CONCLUSION

Higher MG-QOL-15 scores were a risk factor for anxiety and depression in late-onset MG, and women with late-onset MG were more likely to have anxiety and depression than men were.

Eculizumab treatment for myasthenia gravis subgroups: 2021 update

Eculizumab is a recombinant humanized monoclonal antibody that targets the complement protein C5, inhibiting its cleavage into C5a and C5b and ultimately preventing the formation of C5b-9 membrane attack complex (MACs), thereby protecting the neuromuscular junction from the damage of complement activation. In 2017, eculizumab became the second FDA-approved medication for AchR-positive generalized myasthenia gravis (gMG) patients based on the successful results of a randomized, double-blinded, placebo-controlled, phase 2, phase 3 study (the REGAIN trial) and its open-label extension study. Despite the efficacy of eculizumab in treating AchR antibody-positive refractory gMG was demonstrated in the REGAIN study, there is few information on its efficacy in other subgroup of MG patients including seronegative MG, thymoma-associated MG and MG crisis. This narrative review summarizes current clinical studies of eculizumab in these refractory gMG patients, with a focus on the therapeutic efficacy and tolerability in different subgroup of MG.

Efficacy and Safety of Immunotherapies in Refractory Myasthenia Gravis: A Systematic Review and Meta-Analysis

Introduction: Approximately 10–20% of patients WITH myasthenia gravis (MG) are refractory to conventional immunotherapies. The purpose of this study was to conduct a systematic review and meta-analysis to explore the optimal therapies for refractory MG.

Method: Correlative studies were performed through a search in PubMed, Cochrane Library, and Embase databases. The primary outcome was defined by changes in the quantitative myasthenia gravis score (QMG). Secondary outcomes were defined by the Myasthenia Gravis Activities of Daily Living Scale (MG-ADL), Myasthenia Gravis Foundation of America (MGFA) post intervention status, adverse events, and disease exacerbation after treatment.

Result: A total of 16 studies were included with 403 patients with refractory MG on therapies with rituximab, eculizumab, tacrolimus, and cladribine. Therapeutic efficacy of rituximab and eculizumab was identified with an estimated reduction in QMG score (4.158 vs. 6.928) and MG-ADL (4.400 vs. 4.344), respectively. No significant changes were revealed in efficacy or exacerbation density between the two independent therapeutic cohorts. The estimated adverse event density of eculizumab was more significant than that in the rituximab group (1.195 vs. 0.134 per patient-year), while the estimated serious event density was similar.

Conclusion: The efficacy and safety of rituximab and eculizumab have been approved in patients with refractory MG. Rituximab had a superior safety profile than eculizumab with a lower incidence of adverse events.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021236818, identifier CRD42021236818.

Quantitative evaluation of drug efficacy in the treatment of myasthenia gravis

OBJECTIVES

This study aimed to quantitatively evaluate placebo effect and drug efficacy characteristics and identify associated factors that affect quantitative myasthenia gravis (MG) score (QMGs) and MG activities of daily living score (MG-ADLs) in patients with MG.

METHODS

Randomized placebo-controlled clinical trials were comprehensively searched in public databases (PubMed, EMBASE, and Cochrane Library databases).A model-based meta-analysis was developed to describe time-course about drug efficacy and placebo effect.

RESULTS

Twelve articles including 13 trials (673 participants) that were eligible for this study evaluated four immunosuppressants (tacrolimus, cyclosporine, prednisone, and mycophenolate mofetil) and five targeted therapy drugs (eculizumab, belimumab, zilucoplan, efgartigimod, and iscalimab). The pharmacodynamic model showed that eculizumab had the highest efficacy in reducing QMGs scores (3.66 points), and efgartigimod had the highest efficacy in reducing MG-ADLs scores (1.97 points). The placebo effect of QMGs and MG-ADLs increased apparently with time and reached 52% and 90% of their maximum effect in 12 weeks, respectively. In addition, this study found that the activities of daily living ability increased with the increase of the proportion of patients undergoing thymectomy.

CONCLUSION

This study analyzed the efficacy characteristics of nine drugs. The present findings provide necessary quantitative information for drug development of MG.

Effects of Natural Products on Neuromuscular Junction

Neuromuscular junction (NMJ) disorders result from damage, malfunction or absence of one or more key proteins involved in neuromuscular transmission, comprising a wide range of disorders. The most common pathology is antibody-mediated or downregulation of ion channels or receptors, resulting in Lambert-Eaton myasthenic syndrome, myasthenia gravis, and acquired neuromyotonia (Isaac's syndrome), and rarely congenital myasthenic syndromes caused by mutations in NMJ proteins. A wide range of symptomatic treatments, immunomodulating therapies, or immunosuppressive drugs have been used to treat NMJ diseases. Future research must be directed at better understanding of the pathogenesis of these diseases, and developing novel disease-specific treatments. Numerous secondary metabolites, especially alkaloids isolated from plants have been used to treat NMJ diseases in traditional and clinical practices. An ethnopharmacological approach has provided leads for identifying new treatment for NMJ diseases. In this review, we performed a literature survey in Pubmed, Science Direct, and Google Scholar to gather information on drug discovery from plant sources for NMJ disease treatments. To date, most research has focused on the effect of herbal remedies on cholinesterase inhibitory and antioxidant activities. This review provides leads for identifying potential new drugs from plant sources for the treatment of NMJ diseases.

Nomogram for short-term outcome assessment in AChR subtype generalized myasthenia gravis

BACKGROUND

An accurate prediction for prognosis can help in guiding the therapeutic options and optimizing the trial design for generalized myasthenia gravis (gMG). We aimed to develop and validate a predictive nomogram to assess the short-term outcome in patients with the anti-acetylcholine receptor (AChR) subtype gMG.

METHODS

We retrospectively reviewed 165 patients with AChR subtype gMG who were immunotherapy naïve at the first visit from five tertiary centers in China. The short-term clinical outcome is defined as the achievement of minimal symptom expression (MSE) at 12 months. Of them, 120 gMG patients from Huashan Hospital were enrolled to form a derivation cohort (n = 96) and a temporal validation cohort (n = 24) for the nomogram. Then, this nomogram was externally validated using 45 immunotherapy naïve AChR subtype gMG from the other four hospitals. Multivariate logistic regression was used to screen independent factors and construct the nomogram.

RESULTS

MSE was achieved in 70 (72.9%), 20 (83.3%), and 33 (73.3%) patients in the training, temporal validation, and external validation cohort, respectively. The duration ≤ 12 months (p = 0.021), ocular score ≤ 2 (p = 0.006), QMG score > 13 (p = 0.008), and gross motor score ≤ 9 (p = 0.006) were statistically associated with MSE in AChR subtype gMG. The nomogram has good performance in predicting MSE as the concordance indexes are 0.81 (95% CI, 0.72-0.90) in the development cohort, 0.944 (95% CI, 0.83-1.00) in the temporal validation cohort, and 0.773 (95% CI, 0.63-0.92) in the external validation cohort.

CONCLUSION

The nomogram achieved an optimal prediction of MSE in AChR subtype gMG patients using the baseline clinical characters.

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.

Autoimmune Channelopathies at Neuromuscular Junction

The neuromuscular junction, also called myoneural junction, is a site of chemical communication between a nerve fiber and a muscle cell. There are many types of channels at neuromuscular junction that play indispensable roles in neuromuscular signal transmission, such as voltage-gated calcium channels and voltage-gated potassium channels on presynaptic membrane, and acetylcholine receptors on post-synaptic membrane. Over the last two decades, our understanding of the role that autoantibodies play in neuromuscular junction disorders has been greatly improved. Antibodies against these channels cause a heterogeneous group of diseases, such as Lambert-Eaton syndrome, Isaacs' syndrome and myasthenia gravis. Lambert-Eaton syndrome is characterized by late onset of fatigue, skeletal muscle weakness, and autonomic symptoms. Patients with Isaacs' syndrome demonstrate muscle cramps and fasciculation. Myasthenia gravis is the most common autoimmune neuromuscular junction channelopathy characterized by fluctuation of muscle weakness. All these disorders have a high risk of tumor. Although these channelopathies share some common features, they differ for clinical features, antibodies profile, neurophysiological features, and treatments. The purpose of this review is to give a comprehensive insight on recent advances in autoimmune channelopathies at the neuromuscular junction.

Immunosuppressive and monoclonal antibody treatment for myasthenia gravis: A network meta-analysis

BACKGROUND

We intended to compare and rank all the immunotherapies including immunosuppressant agents or monoclonal antibodies for myasthenia gravis (MG).

METHODS

A network meta-analysis was performed to synthesize the direct evidence and indirect evidence. Quantitative MG score (QMGS) was defined as the primary outcome. The secondary outcomes included the glucocorticoid reduction and hazard ratios (HR) from the counts of adverse events (AEs).

RESULTS

We identified 14 studies including 808 MG patients. For the primary outcome, cyclosporine A (CsA) was hierarchically the best with statistical significances of -1.18 (-1.81, -0.59) vs placebo (PLA), -0.98 (-1.72, -0.23) vs mycophenolate mofetil, and -0.77 (-1.57, -0.032) vs tacrolimus (TAC). When the intervention periods were controlled, both eculizumab (ECZ) of -1.50 (-2.81, -0.18) and CsA of -1.23 (-1.81, -0.64) vs PLA reached a statistical significance. Belimumab and ECZ ranked the most tolerable therapies while CsA of 2.41 (0.58, 10.01) ranked the last vs PLA.

CONCLUSION

These findings demonstrated that ECZ represented the most effective and tolerable therapeutic alternative to be recommended for refractory MG. TAC may be a beneficial therapy to treat MG extensively while the efficacy of CsA and cyclophosphamide may be limited by their multiple or severe AEs.