Long-term safety and efficacy of eculizumab in generalized myasthenia gravis

Elevated C1s/C1-INH in serum and plasma of myasthenia gravis patients

Myasthenia Gravis (MG) is an autoimmune neuromuscular disorder where acetylcholine receptor (AChR) antibodies induce membrane attack complex formation at the muscle membrane. The C1-inhibitor (C1-INH) regulates the classical pathway and is a promising marker in other autoimmune disorders. Treatment options for AChR antibody MG include complement inhibitors; nevertheless, the early pathway activation in MG remains unclear. Serum and plasma C1s-C1-INH levels were higher in MG patients than in matched healthy controls, supporting early classical pathway activation in most MG patients. These findings allow prospective validation studies of activated C1s as a putative treatment target and potential accompanying biomarker in MG.

The efficacy and safety of eculizumab in patients and the role of C5 polymorphisms

Eculizumab is an orphan drug with indications for extremely rare autoimmune disorders. It is primarily prescribed for use in patients with paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome; but is also highly effective in the treatment of myasthenia gravis, among others. By binding to the C5 protein in the complement system, eculizumab effectively inhibits cellular hemolysis and autoimmune reactions. Despite this effective treatment, some patients reported no improvement in symptoms. Genetic sequencing revealed three distinct C5 mutations in the non-responders and these polymorphisms appeared to be most prevalent among Japanese, Korean and African populations. Here, we present an overview of the current and potential future applications of eculizumab, as well as the disadvantages of eculizumab treatment in patients with C5 polymorphisms.

United States clinical practice experience with eculizumab in myasthenia gravis: symptoms, function, and immunosuppressant therapy use

BACKGROUND/OBJECTIVES

The phase 3 REGAIN study and its open-label extension demonstrated the efficacy of the complement C5 inhibitor eculizumab in patients with treatment-refractory, acetylcholine receptor antibody-positive generalized myasthenia gravis (gMG). The aim of the ELEVATE study was to assess the effectiveness of eculizumab in clinical practice in adults with MG in the United States.

METHODS

A retrospective chart review was conducted in adults with MG who initiated eculizumab treatment between October 23, 2017 and December 31, 2019. Outcomes assessed before and during eculizumab treatment using a pre- versus post-treatment study design included Myasthenia Gravis-Activities of Daily Living (MG-ADL) total scores; minimal symptom expression (MSE); physician impression of clinical change; minimal manifestation status (MMS); and concomitant medication use.

RESULTS

In total, 119 patients were included in the study. A significant reduction was observed in mean MG-ADL total score, from 8.0 before eculizumab initiation to 5.4 at 3 months and to 4.7 at 24 months after eculizumab initiation (both p < 0.001). At 24 months after eculizumab initiation, MSE was achieved by 19% of patients. MMS or better was achieved by 30% of patients at 24 months. Additionally, 64% of patients receiving prednisone at eculizumab initiation had their prednisone dosage reduced during eculizumab treatment and 13% discontinued prednisone; 32% were able to discontinue nonsteroidal immunosuppressant therapy.

DISCUSSION

Eculizumab treatment was associated with sustained improvements in MG-ADL total scores through 24 months in adults with MG. Prednisone dosage was reduced in approximately two-thirds of patients, suggesting a steroid-sparing effect for eculizumab.

Treating myasthenia gravis beyond the eye clinic

Myasthenia gravis (MG) is one of the most well characterised autoimmune disorders affecting the neuromuscular junction with autoantibodies targeting the acetylcholine receptor (AChR) complex. The vast majority of patients present with ocular symptoms including double vision and ptosis, but may progress on to develop generalised fatiguable muscle weakness. Severe involvement of the bulbar muscles can lead to dysphagia, dysarthria and breathing difficulties which can progress to myasthenic crisis needing ventilatory support. Given the predominant ocular onset of the disease, it is important that ophthalmologists are aware of the differential diagnosis, investigations and management including evolving therapies. When the disease remains localised to the extraocular muscles (ocular MG) IgG1 and IgG3 antibodies against the AChR (including clustered AChR) are present in nearly 50% of patients. In generalised MG this is seen in nearly 90% patients. Other antibodies include those against muscle specific tyrosine kinase (MuSK) and lipoprotein receptor related protein 4 (LRP4). Even though decremental response on repetitive nerve stimulation is the most well recognised neurophysiological abnormality, single fibre electromyogram (SFEMG) in experienced hands is the most sensitive test which helps in the diagnosis. Initial treatment should be using cholinesterase inhibitors and then proceeding to immunosuppression using corticosteroids and steroid sparing drugs. Patients requiring bulbar muscle support may need rescue therapies including plasma exchange and intravenous immunoglobulin (IVIg). Newer therapeutic targets include those against the B lymphocytes, complement system, neonatal Fc receptors (FcRn) and various other elements of the immune system.

Therapeutic Approach to Autoimmune Neurologic Disorders

OBJECTIVE

Autoimmune neurologic disorders encompass a broad category of diseases characterized by immune system attack of the central, peripheral, or autonomic nervous systems. This article provides information on both acute and maintenance immunotherapy used to treat autoimmune neurologic disorders as well as a review of symptomatic management and special considerations when caring for patients with these diseases.

LATEST DEVELOPMENTS

Over the past 20 years, more than 50 antibodies have been identified and associated with autoimmune neurologic disorders. Although advances in diagnostic testing have allowed for more rapid diagnosis, the therapeutic approach to these disorders has largely continued to rely on expert opinion, case series, and case reports. With US Food and Drug Administration (FDA) approval of biologic agents to treat neuromyelitis optica spectrum disorder (NMOSD) and myasthenia gravis as well as ongoing clinical trials for the treatment of autoimmune encephalitis, the landscape of immunotherapy options continues to expand. Consideration of the unique pathogenesis of individual autoimmune neurologic disorders as well as the mechanism of action of the diverse range of treatment options can help guide treatment decisions today while evidence from clinical trials informs new therapeutics in the future.

ESSENTIAL POINTS

Recognizing patients who have a clinical history and examination findings concerning for autoimmune neurologic disorders and conducting a thorough and directed imaging and laboratory evaluation aimed at ruling out mimics, identifying specific autoimmune syndromes, and screening for factors that may have an impact on immunotherapy choices early in the clinical course are essential to providing optimal care for these patients. Providers must consider immunotherapy, symptomatic treatment, and a multidisciplinary approach that addresses each patient's unique needs when treating patients with autoimmune neurologic disorders.

Integrated Applied Clinical Pharmacology in the Advancement of Rare and Ultra-Rare Disease Therapeutics

The introduction of safe and effective rare/ultra-rare disease treatments is a focus of many biotherapeutic enterprises. Despite this increased activity, a significant unmet need remains, and the responsibility to meet this need is augmented by enhanced genomic, biologic, medical, analytical, and informatic tools. It is recognized that the development of an effective and safe rare/ultra-rare disease therapeutic faces a number of challenges with an important role noted for clinical pharmacology. Clinical pharmacology is foundationally an integrative discipline which must be embedded in and is interdependent upon understanding the pathogenic biology, clinical presentation, disease progression, and end-point assessment of the disease under study. This manuscript presents an overview and two case examples of this integrative approach, the development of C5-targeted therapeutics for the treatment of generalized myasthenia gravis and asfotase alpha for the treatment of hypophosphatasia. The two presented case examples show the usefulness of understanding the biological drivers and clinical course of a rare disease, having relevant animal models, procuring informative natural history data, importing assessment tools from relevant alternative areas, and using integrated applied clinical pharmacology to inform target engagement, dose, and the cascade of pharmacodynamic and clinical effects that follow. Learnings from these programs include the importance of assuring cross-validation of assays throughout a development program and continued commitment to understanding the relationship among the array of Pd end points and clinical outcomes. Using an integrative approach, substantive work remains to be done to meet the unmet needs of patients with rare/ultra-rare disease.

Therapeutic challenges and unmet needs in the management of myasthenia gravis: an Italian expert opinion

Myasthenia gravis (MG) is a rare, autoimmune, neurological disorder. Most MG patients have autoantibodies against acetylcholine receptors (AChRs). Some have autoantibodies against muscle-specific tyrosine kinase (MuSK) or lipoprotein-receptor-related protein 4 (LRP4), and some are seronegative. Standard of care, which includes anti-cholinesterase drugs, thymectomy, corticosteroids (CS), and off-label use of non-steroidal immunosuppressive drugs (NSISTs), is bounded by potential side effects and limited efficacy in refractory generalized MG (gMG) patients. This highlights the need for new therapeutic approaches for MG. Eculizumab, a monoclonal antibody that inhibits the complement system, has been recently approved in Italy for refractory gMG. A panel of 11 experts met to discuss unmet therapeutic needs in the acute and chronic phases of the disease, as well as the standard of care for refractory patients. Survival was emphasized as an acute phase outcome. In the chronic phase, persistent remission and early recognition of exacerbations to prevent myasthenic crisis and respiratory failure were considered crucial. Refractory patients require treatments with fast onset of action, improved tolerability, and the ability to slow disease progression and increase life expectancy. The Panel agreed that eculizumab would presumably meet the therapeutic needs of many refractory gMG patients. The panel concluded that the unmet needs of current standard of care treatments for gMG are significant. Evaluating new therapeutic options accurately is essential to find the best balance between efficacy and tolerability for each patient. Collecting real-world data on novel molecules in routine clinical practice is necessary to address unmet needs.

Eculizumab in Adolescent Patients With Refractory Generalized Myasthenia Gravis: A Phase 3, Open-Label, Multicenter Study

BACKGROUND

This study evaluated the efficacy and safety of eculizumab, a terminal complement C5 inhibitor, in juvenile generalized myasthenia gravis (gMG).

METHODS

Adolescents aged 12 to 17 years with refractory anti-acetylcholine receptor (AChR) antibody-positive gMG received eculizumab (weekly induction [one to two doses of 600 mg or four doses of 900 mg] followed by maintenance doses [300 to 1200 mg] every two weeks for up to 26 weeks) in a phase 3, open-label multicenter study (NCT03759366). Change from baseline to week 26 in Quantitative Myasthenia Gravis (QMG) total score (primary end point) and secondary end points including Myasthenia Gravis-Activities of Daily Living (MG-ADL) total score, Myasthenia Gravis Composite score, Myasthenia Gravis Foundation of America postintervention status, EuroQol 5-Dimensions (Youth) and Neurological Quality-of-Life Pediatric Fatigue questionnaire scores, as well as pharmacokinetics, pharmacodynamics, and safety, were recorded.

RESULTS

Eleven adolescents (mean ± S.D. age 14.8 ± 1.8 years) were enrolled; 10 completed the primary evaluation period. Least-squares mean changes from baseline at week 26 were -5.8 (standard error [SE] 1.2; P = 0.0004) for QMG total score and -2.3 (SE 0.6; P = 0.0017) for MG-ADL total score. Overall, the primary and all secondary efficacy end point analyses met statistical significance from the first assessment and were sustained throughout. Complete terminal complement inhibition was sustained through 26 weeks in all patients. Treatment-emergent adverse events were all mild/moderate and predominantly unrelated to eculizumab.

CONCLUSIONS

Eculizumab was effective in reducing disease burden and was well tolerated in adolescents with refractory AChR antibody-positive gMG.

Expert consensus recommendations for improving and standardising the assessment of patients with generalised myasthenia gravis

BACKGROUND

Regular and consistent disease assessment could provide a clearer picture of burden in generalised myasthenia gravis (gMG) and improve patient care; however, the use of assessment tools in practice lacks standardisation. This modified Delphi approach was taken to review current evidence on assessment tool use in gMG and develop expert-derived consensus recommendations for good practice.

METHODS

A European expert panel of 15 experienced gMG neurologists contributed to development of this consensus, four of whom formed a lead Sub-committee. The PICO (Population, Intervention, Control, Outcomes) framework was used to define six clinical questions on gMG assessment tools, a systematic literature review was conducted, and evidence-based statements were developed. According to a modified Delphi voting process, consensus was reached when ≥70% of the experts rated agreement with a statement as ≥8 on a scale of 1-10.

RESULTS

Eighteen expert- and evidence-based consensus statements based on six themes were developed. Key recommendations include: consistent use of the Myasthenia Gravis Activities of Daily Living score (MG-ADL) across clinical settings, followed by a simple question (e.g., Patient Acceptable Symptom State [PASS]) or scale to determine patient satisfaction in clinical practice; use of a Quantitative Myasthenia Gravis [QMG] or quality of life [QoL] assessment when the MG-ADL indicates disease worsening; and consideration of symptom state to determine the timing and frequency of recommended assessments. Expert panel consensus was reached on all 18 statements after two voting rounds.

CONCLUSIONS

This process provided evidence- and expert consensus-based recommendations for the use of objective and subjective assessment tools across gMG research and care to improve management and outcomes for patients.

Immune mediated myasthenia gravis in children, current concepts and new treatments: A narrative review article

Myasthenia gravis (MG) is the most frequent transmission disease in the neuromuscular junction. Juvenile myasthenia gravis (JMG) is an autoimmune antibody-mediated disease of postsynaptic endplate defined as MG presentation in patients before the age of 18 years old. While many clinical features of JMG are identical to the adults, there are some significant differences between them regarding presentation, clinical course, antibody level, and thymus histopathology. In JMG, ocular symptoms are more frequent, the clinical course is comparably benign, and the outcome is better than adult MG. Antibodies attack the muscle endplate proteins in the postsynaptic membrane and interfere with transmission. These antibodies in most patients are against the acetylcholine receptors, but they may also be directed toward muscle-specific kinase, lipoprotein-related protein 4, and agrin. Findings show racial influences and genetic effects on the occurrence of JMG. The essential clinical symptom is fatigable weakness of muscles that can be in the form of isolated ocular type or more disseminated weakness. The diagnosis of JMG is essentially clinical, with fluctuating patterns of weakness and easy fatigability, but a series of diagnostic evaluations can confirm the diagnosis. Precise diagnostic evaluation and distinction from congenital myasthenic syndromes is critical. The treatment plan is conducted according to the clinical course (ocular or generalized), antibody type, and disease severity. The mainstay of treatment includes symptomatic therapy, long-lasting immunosuppressive treatment and treatment of myasthenic crisis. Novel medications are introduced and conducted to the specific pathophysiologic mechanisms of the disease, and they are used primarily in the refractory MG.

Targeting autoimmune mechanisms by precision medicine in Myasthenia Gravis

Myasthenia Gravis (MG) is a chronic disabling autoimmune disease caused by autoantibodies to the neuromuscular junction (NMJ), characterized clinically by fluctuating weakness and early fatigability of ocular, skeletal and bulbar muscles. Despite being commonly considered a prototypic autoimmune disorder, MG is a complex and heterogeneous condition, presenting with variable clinical phenotypes, likely due to distinct pathophysiological settings related with different immunoreactivities, symptoms' distribution, disease severity, age at onset, thymic histopathology and response to therapies. Current treatment of MG based on international consensus guidelines allows to effectively control symptoms, but most patients do not reach complete stable remission and require life-long immunosuppressive (IS) therapies. Moreover, a proportion of them is refractory to conventional IS treatment, highlighting the need for more specific and tailored strategies. Precision medicine is a new frontier of medicine that promises to greatly increase therapeutic success in several diseases, including autoimmune conditions. In MG, B cell activation, antibody recycling and NMJ damage by the complement system are crucial mechanisms, and their targeting by innovative biological drugs has been proven to be effective and safe in clinical trials. The switch from conventional IS to novel precision medicine approaches based on these drugs could prospectively and significantly improve MG care. In this review, we provide an overview of key immunopathogenetic processes underlying MG, and discuss on emerging biological drugs targeting them. We also discuss on future direction of research to address the need for patients' stratification in endotypes according with genetic and molecular biomarkers for successful clinical decision making within precision medicine workflow.

Refocusing generalized myasthenia gravis: Patient burden, disease profiles, and the role of evolving therapy

BACKGROUND AND PURPOSE

Generalized myasthenia gravis (gMG) continues to present significant challenges for clinical management due to an unpredictable disease course, frequent disease fluctuations, and varying response to therapy. The recent availability of new pharmacologic therapies presents a valuable opportunity to reevaluate how this disease is classified, assessed, and managed and identify new ways to improve the clinical care of patients with gMG.

METHODS

Narrative review was made of publications identified via searches of PubMed and selected congresses (January 2000-September 2022).

RESULTS

New consensus definitions are required to ensure consistency, to better characterize patients, and to identify patients who will benefit from specific drugs and earlier use of these agents. There is a need for more frequent, standardized patient assessment to identify the cause of motor function deficits, provide a clearer picture of the disease burden and its impact on daily living and quality of life (QoL), and better support treatment decision-making. Novel approaches that target different components of the immune system will play a role in more precise treatment of patients with gMG, alongside the development of new algorithms to guide individualized patient management.

CONCLUSIONS

gMG has a physical, mental, and social impact, resulting in a considerable burden of disease and substantially decreased QoL, despite standard treatments. The availability of novel, targeted treatments that influence key pathological mediators of gMG, together with new biomarkers, offers the potential to optimize patient management and ultimately enables a greater number of patients to achieve minimal manifestation status and a reduced burden of disease.

Advancements and prospects of novel biologicals for myasthenia gravis: toward personalized treatment based on autoantibody specificities

Myasthenia gravis (MG) is an antibody-mediated autoimmune disease with a prevalence of 150-250 cases per million individuals. Autoantibodies include long-lived antibodies against the acetylcholine receptor (AChR), mainly of the IgG1 subclass, and IgG4, produced almost exclusively by short-lived plasmablasts, which are prevalent in muscle-specific tyrosine kinase (MuSK) myasthenia gravis. Numerous investigations have demonstrated that MG patients receiving conventional medication today still do not possess satisfactory symptom control, indicating a substantial disease burden. Subsequently, based on the type of the autoantibody and the pathogenesis, we synthesized the published material to date and reached a conclusion regarding the literature related to personalized targeted therapy for MG. Novel agents for AChR MG have shown their efficacy in clinical research, such as complement inhibitors, FcRn receptor antagonists, and B-cell activating factor (BAFF) inhibitors. Rituximab, a representative drug of anti-CD20 therapy, has demonstrated benefits in treatment of MuSK MG patients. Due to the existence of low-affinity antibodies or unidentified antibodies that are inaccessible by existing methods, the treatment for seronegative MG remains complicated; thus, special testing and therapy considerations are necessary. It may be advantageous to initiate the application of novel biologicals at an early stage of the disease. Currently, therapies can also be combined and individualized according to different types of antibodies. With such a wide range of drugs, how to tailor treatment strategies to patients with various conditions and find the most suitable solution for each MG profile are our necessary and urgent aims.

Real-world experience with eculizumab and switching to ravulizumab for generalized myasthenia gravis

OBJECTIVE

Eculizumab and ravulizumab are complement protein C5 inhibitors, showing efficacy and tolerability for patients with anti-acetylcholine receptor-positive (AChR+) generalized myasthenia gravis (gMG) in phase 3 clinical trials and subsequent analyses. The purpose of the present study was to evaluate the clinical significance of eculizumab and switching to ravulizumab for refractory AChR+ gMG patients in the real-world experience.

METHODS

Among the database of Japan MG registry survey 2021, we studied AChR+ gMG patients who received eculizumab. We also evaluated these patients who switched from eculizumab to ravulizumab. Responder was defined as an improvement of at least 3 points in MG-ADL. We performed a questionnaire of preference between eculizumab and ravulizumab.

RESULTS

Among 1,106 patients with AChR+ gMG, 36 patients (3%) received eculizumab (female 78%, mean age 56.0 years). Eculizumab was preferentially used in severe and refractory MG patients. The duration of eculizumab treatment was 35 months on average. MG-ADL improved from 9.4 ± 4.9 to 5.9 ± 5.1, and 25 (70%) of the 36 gMG patients were responders. Postintervention status was markedly improved after the eculizumab treatment. Of 13 patients who did not continue eculizumab, 6 showed insufficiencies. Early onset MG was most effective. However, 15 patients switching from eculizumab to ravulizumab kept favorable response and tolerability. Questionnaire surveys showed preference for ravulizumab over eculizumab.

INTERPRETATION

Eculizumab and switching to ravulizumab showed to be effective for refractory AChR+ gMG patients in clinical settings.

Generalized myasthenia gravis with acetylcholine receptor antibodies: A guidance for treatment

BACKGROUND

Generalized myasthenia gravis (MG) with antibodies against the acetylcholine receptor is a chronic disease causing muscle weakness. Access to novel treatments warrants authoritative treatment recommendations. The Nordic countries have similar, comprehensive health systems, mandatory health registers, and extensive MG research.

METHODS

MG experts and patient representatives from the five Nordic countries formed a working group to prepare treatment guidance for MG based on a systematic literature search and consensus meetings.

RESULTS

Pyridostigmine represents the first-line symptomatic treatment, while ambenonium and beta adrenergic agonists are second-line options. Early thymectomy should be undertaken if a thymoma, and in non-thymoma patients up to the age of 50-65 years if not obtaining remission on symptomatic treatment. Most patients need immunosuppressive drug treatment. Combining corticosteroids at the lowest possible dose with azathioprine is recommended, rituximab being an alternative first-line option. Mycophenolate, methotrexate, and tacrolimus represent second-line immunosuppression. Plasma exchange and intravenous immunoglobulin are used for myasthenic crises and acute exacerbations. Novel complement inhibitors and FcRn blockers are effective and fast-acting treatments with promising safety profiles. Their use depends on local availability, refunding policies, and cost-benefit analyses. Adapted physical training is recommended. Planning of pregnancies with optimal treatment, information, and awareness of neonatal MG is necessary. Social support and adaptation of work and daily life activities are recommended.

CONCLUSIONS

Successful treatment of MG rests on timely combination of different interventions. Due to spontaneous disease fluctuations, comorbidities, and changes in life conditions, regular long-term specialized follow-up is needed. Most patients do reasonably well but there is room for further improvement. Novel treatments are promising, though subject to restricted access due to costs.

Efficacy of ravulizumab in patients with generalized myasthenia gravis by time from diagnosis: A post hoc subgroup analysis of the CHAMPION MG study

INTRODUCTION/AIMS

The CHAMPION MG study demonstrated that ravulizumab significantly improved Myasthenia Gravis-Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) total scores versus placebo in adults with acetylcholine receptor antibody-positive generalized myasthenia gravis (AChR+ gMG). This post hoc analysis aimed to assess these outcomes by time from MG diagnosis.

METHODS

Changes from baseline to week 26 in MG-ADL and QMG total scores were analyzed by time from MG diagnosis to study entry (≤2 vs. >2 years). Within each subgroup, least-squares (LS) mean changes for ravulizumab and placebo were compared using mixed models for repeated measures.

RESULTS

In ravulizumab-treated patients, differences in LS mean (standard error of the mean) changes from baseline to week 26 were not statistically significant in the ≤2-years subgroup versus the >2-years subgroup for MG-ADL (-4.3 [0.70] vs. -2.9 [0.37]; p = .0511) or QMG (-4.3 [0.94] vs. -2.5 [0.50]; p = .0822) scores. No clear trends were observed in the placebo group. LS mean changes from baseline were significantly greater for ravulizumab versus placebo in both the ≤2 and >2 years from diagnosis subgroups for MG-ADL and QMG scores (all p < .05). The difference in treatment effect between the ≤2-years and >2-years subgroups was not statistically significant. No clinically meaningful between-subgroup differences in treatment-emergent adverse events were observed in ravulizumab-treated patients.

DISCUSSION

Ravulizumab treatment improved clinical outcomes for patients with AChR+ gMG regardless of time from diagnosis. A numerical trend was observed favoring greater treatment effect with earlier versus later treatment after diagnosis. Further studies are required for confirmation.

Long-term safety and efficacy of zilucoplan in patients with generalized myasthenia gravis: interim analysis of the RAISE-XT open-label extension study

Background

Generalized myasthenia gravis (gMG) is a chronic, unpredictable disease associated with high treatment and disease burdens, with a need for more effective and well-tolerated treatments.

Objectives

To evaluate the long-term safety, tolerability, and efficacy of zilucoplan in a mild-to-severe, acetylcholine receptor autoantibody-positive (AChR+) gMG population.

Design

Ongoing, multicenter, phase III open-label extension (OLE) study.

Methods

Eligible patients had completed a qualifying randomized, placebo-controlled phase II or phase III zilucoplan study and received daily, self-administered subcutaneous 0.3 mg/kg zilucoplan. The primary endpoint was incidence of treatment-emergent adverse events (TEAEs). Secondary efficacy endpoints included change from baseline in Myasthenia Gravis Activities of Daily Living (MG-ADL) score.

Results

In total, 200 patients enrolled. At the cut-off date (8 September 2022), median (range) exposure to zilucoplan in RAISE-XT was 1.2 (0.11-4.45) years. Mean age at OLE baseline was 53.3 years. A total of 188 (94%) patients experienced a TEAE, with the most common being MG worsening (n = 52, 26%) and COVID-19 (n = 49, 25%). In patients who received zilucoplan 0.3 mg/kg in the parent study, further improvements in MG-ADL score continued through to Week 24 (least squares mean change [95% confidence interval] from double-blind baseline -6.06 [-7.09, -5.03]) and were sustained through to Week 60 (-6.04 [-7.21, -4.87]). In patients who switched from placebo in the parent study, rapid improvements in MG-ADL score were observed at the first week after switching to zilucoplan; further improvements were observed at Week 24, 12 weeks after switching (-6.46 [-8.19, -4.72]), and were sustained through to Week 60 (-6.51 [-8.37, -4.65]). Consistent results were observed in other efficacy endpoints.

Conclusion

Zilucoplan demonstrated a favorable long-term safety profile, good tolerability, and sustained efficacy through to Week 60 with consistent benefits in a broad AChR+ gMG population. Additional long-term data will be available in future analyses.

Trial registration

ClinicalTrials.gov identifier: NCT04225871 (https://clinicaltrials.gov/ct2/show/NCT04225871).

[Myasthenia Gravis - Update]

Myasthenia gravis - still a challenge for sufferers and doctors in 2023. But which therapy is best suited? Our clinically experienced experts have summarized the current guidelines for diagnosis and treatment in order to provide optimal support for those affected. Find out how you can carry out a quick and targeted diagnosis and which treatment options are available to alleviate the course of the disease.

How should newer therapeutic agents be incorporated into the treatment of patients with myasthenia gravis?

Generalized myasthenia gravis (gMG) is a postsynaptic neuromuscular junction disorder that results in fatigable muscle weakness. The traditional treatment approach includes the use of acetylcholinesterase inhibitors, corticosteroids, and steroid-sparing immunosuppressant therapies (ISTs) for chronic management, whereas exacerbations and crises are managed with intravenous immunoglobulin (IVIg) and plasma exchange (PLEX). Over the past 6 years, four new therapeutic agents with novel immunological mechanisms of action-complement and neonatal Fc receptor (FcRn) inhibition-were approved as a result of clinically significant improvement in gMG symptoms of those treated with these newer agents in Phase 3 clinical trials. At present, it is unclear when and in whom to initiate these therapeutic agents and how to integrate them into the current treatment paradigm. When selecting a newer therapeutic agent, we use a simple equation: Value = Clinical Improvement/(Cost + Side Effects + Treatment Burden), which guides our decision-making. We consider using these novel therapeutic agents in two specific clinical situations. Firstly, the newer agents are fast-acting, suggesting they can be used in clinically unstable patients as "bridge therapy," and secondly, they provide additional options for those patients considered treatment-refractory. There are downsides, however, including treatment cost, unique side effect profiles, and intravenous and subcutaneous drug administration (though for some, this may be an advantage). As additional drugs enter the marketplace with unique mechanisms of action, routes of administration, and dosing schedules, the placement of the novel therapeutic agents in the gMG treatment algorithm will likely evolve.

Eculizumab for myasthenic exacerbation during treatment with immune-checkpoint inhibitors

OBJECTIVE

To test the complement inhibitor eculizumab in the treatment of MG exacerbation during therapy with the immune-checkpoint inhibitor (ICI) pembrolizumab, avoiding its discontinuation, which could be detrimental to oncologic course.

METHODS

A 76-year-old male with non-thymomatous generalized anti-AchR + MG (MGFA class IVB), during treatment with pembrolizumab for colorectal cancer, developed a severe myasthenic exacerbation, refractory to steroids and IvIg. Eculizumab was started, without pembrolizumab discontinuation. The patient was prospectively followed using MGFA, MG Activities of Daily Living (MG-ADL), Quantitative MG (QMG), MG Composite (MGC), and MG Quality of Life 15 (MG-QOL-15).

RESULTS

After an 18-week follow-up, the patient presented a progressive improvement in scores on all scales, achieving a MGFA class IIIB. The percentage improvement was 40% in MG-ADL, 36% in MG Composite, and about 30% in QMG. Bulbar symptoms improved by about 70% in MG-ADL and MG Composite and 40% in QMG. Eculizumab was well tolerated and pembrolizumab regularly continued, with a good control of cancer progression.

DISCUSSION

Eculizumab potentially offers a mechanism-based treatment of MG in patients under anti-programmed cell death protein 1 (PD-1) agents, without interfering with their mechanism of action and avoiding their discontinuation. Larger case series deserve to be evaluated.

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.

Burden of illness and costs in patients with myasthenia gravis currently receiving treatment in the United States

INTRODUCTION/AIMS

If myasthenia gravis (MG) symptoms are inadequately controlled, patients may experience exacerbations or life-threatening myasthenic crises. Patients with inadequately controlled MG symptoms tend to be treated with chronic intravenous immunoglobulin (IVIg) therapy and/or multiple immunosuppressant therapies (ISTs). This study aimed to examine disease burden, healthcare resource utilization, and associated costs in these patients.

METHODS

This was a retrospective observational study using a claims database. Patients with MG were classified into three cohorts based on treatment over a 1-y follow-up period: (a) treated with four or more IVIg episodes (chronic IVIg cohort); (b) received two or more non-steroidal ISTs (NSISTs) sequentially (multiple NSIST cohort); (c) received neither chronic IVIg nor multiple NSISTs (reference cohort). Incidences of crises and exacerbations and annual healthcare costs in each cohort were estimated.

RESULTS

In total, 3516 patients with MG were included in the analysis. Compared with the reference cohort (n = 2992), the MG crisis rate was approximately twice as high in both the chronic IVIg (n = 324) and multiple NSIST (n = 291) cohorts (p < 0.001); and the MG exacerbation rate was approximately four-fold higher in the chronic IVIg cohort (p < 0.001) and three-fold higher in the multiple NSIST cohort (p < 0.001). Median annual MG-related inflation-adjusted total healthcare costs were higher in the chronic IVIg ($81,900) and multiple NSIST ($30,300) cohorts than in the reference cohort ($2540).

DISCUSSION

The burden of crises/exacerbations was substantially higher and healthcare costs were considerably greater in patients with MG treated with chronic IVIg or multiple NSISTs than in patients not receiving these treatments.

Complement in human disease: approved and up-and-coming therapeutics

The complement system is recognised as a protector against blood-borne pathogens and a controller of immune system and tissue homoeostasis. However, dysregulated complement activity is associated with unwanted or non-resolving immune responses and inflammation, which induce or exacerbate the pathogenesis of a broad range of inflammatory and autoimmune diseases. Although the merit of targeting complement clinically has long been acknowledged, the overall complement drug approval rate has been modest. However, the success of the humanised anti-C5 antibody eculizumab in effectively treating paroxysmal nocturnal haemoglobinuria and atypical haemolytic syndrome has revitalised efforts to target complement therapeutically. Increased understanding of complement biology has led to the identification of novel targets for drug development that, in combination with advances in drug discovery and development technologies, has resulted in a surge of interest in bringing new complement therapeutics into clinical use. The rising number of approved drugs still almost exclusively target rare diseases, but the substantial pipeline of up-and-coming treatment options will possibly provide opportunities to also expand the clinical targeting of complement to common diseases.

Registered trials on novel therapies for myasthenia gravis: a cross-sectional study on ClinicalTrials.gov

Novel biologics in MG therapy research is on the rise. This research aimed to investigate the characteristics of registered trials on novel therapies for myasthenia gravis on ClinicalTrials.gov. This cross-sectional study used a descriptive approach to assess the features of the included trials on ClinicalTrials.gov. We found 62 registered trials from 2007 to 2023 on ClinicalTrials.gov. The results showed a yearly rise in the number of registered trials (r = 0.76, p < 0.001). Following 2017, more industry-sponsored trials were conducted (91.5% [43] vs. 60% [9], p = 0.009), fewer results were released (10.6% [5] vs. 60% [9], p = 0.001), and more trials entered phase 3 (67.4% [31] vs. 20% [2], p = 0.001). The most researched novel medications were neonatal Fc receptor inhibitors (51.2% [21]), complement inhibitors (39.0% [16]), and B cell depletors (14.6% [6]). According to the website's data, the neonatal Fc receptor inhibitors and complement inhibitors were effective in treating myasthenia gravis patients in three trials (NCT03315130, NCT03669588, and NCT00727194). This study provides valuable insights into the profile of registered trials on novel therapies for myasthenia gravis. More clinical studies are needed in the future to prove the value of its application.

Complement and MHC patterns can provide the diagnostic framework for inflammatory neuromuscular diseases

Histopathological analysis stands as the gold standard for the identification and differentiation of inflammatory neuromuscular diseases. These disorders continue to constitute a diagnostic challenge due to their clinical heterogeneity, rarity and overlapping features. To establish standardized protocols for the diagnosis of inflammatory neuromuscular diseases, the development of cost-effective and widely applicable tools is crucial, especially in settings constrained by limited resources. The focus of this review is to emphasize the diagnostic value of major histocompatibility complex (MHC) and complement patterns in the immunohistochemical analysis of these diseases. We explore the immunological background of MHC and complement signatures that characterize inflammatory features, with a specific focus on idiopathic inflammatory myopathies. With this approach, we aim to provide a diagnostic algorithm that may improve and simplify the diagnostic workup based on a limited panel of stainings. Our approach acknowledges the current limitations in the field of inflammatory neuromuscular diseases, particularly the scarcity of large-scale, prospective studies that validate the diagnostic potential of these markers. Further efforts are needed to establish a consensus on the diagnostic protocol to effectively distinguish these diseases.

Myasthenia Gravis Treatment: From Old Drugs to Innovative Therapies with a Glimpse into the Future

Myasthenia gravis (MG) is a rare autoimmune disease that causes debilitating muscle weakness due to impaired neuromuscular transmission. Since most (about 80-90%) MG patients present autoantibodies against the acetylcholine receptor, standard medical therapy consists of symptomatic treatment with acetylcholinesterase inhibitors (e.g., pyridostigmine). In addition, considering the autoimmune basis of MG, standard therapy includes immunomodulating agents, such as corticosteroids, azathioprine, cyclosporine A, and cyclophosphamide. New strategies have been proposed for the treatment of MG and include complement blockade (i.e., eculizumab, ravulizumab, and zilucoplan) and neonatal Fc receptor antagonism (i.e., efgartigimod and rozanolixizumab). The aim of this review is to provide a detailed overview of the pre- and post-marketing evidence on the five pharmacological treatments most recently approved for the treatment of MG, by identifying both preclinical and clinical studies registered in clinicaltrials.gov. A description of the molecules currently under evaluation for the treatment of MG is also provided.

Myasthenia gravis-Pathophysiology, diagnosis, and treatment

Myasthenia gravis (MG) is an autoimmune disease characterized by dysfunction of the neuromuscular junction resulting in skeletal muscle weakness. It is equally prevalent in males and females, but debuts at a younger age in females and at an older age in males. Ptosis, diplopia, facial bulbar weakness, and limb weakness are the most common symptoms. MG can be classified based on the presence of serum autoantibodies. Acetylcholine receptor (AChR) antibodies are found in 80%-85% of patients, muscle-specific kinase (MuSK) antibodies in 5%-8%, and <1% may have low-density lipoprotein receptor-related protein 4 (Lrp4) antibodies. Approximately 10% of patients are seronegative for antibodies binding the known disease-related antigens. In patients with AChR MG, 10%-20% have a thymoma, which is usually detected at the onset of the disease. Important differences between clinical presentation, treatment responsiveness, and disease mechanisms have been observed between these different serologic MG classes. Besides the typical clinical features and serologic testing, the diagnosis can be established with additional tests, including repetitive nerve stimulation, single fiber EMG, and the ice pack test. Treatment options for MG consist of symptomatic treatment (such as pyridostigmine), immunosuppressive treatment, or thymectomy. Despite the treatment with symptomatic drugs, steroid-sparing immunosuppressants, intravenous immunoglobulins, plasmapheresis, and thymectomy, a large proportion of patients remain chronically dependent on corticosteroids (CS). In the past decade, the number of treatment options for MG has considerably increased. Advances in the understanding of the pathophysiology have led to new treatment options targeting B or T cells, the complement cascade, the neonatal Fc receptor or cytokines. In the future, these new treatments are likely to reduce the chronic use of CS, diminish side effects, and decrease the number of patients with refractory disease.

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.

Guideline for the management of myasthenic syndromes

Myasthenia gravis (MG), Lambert-Eaton myasthenic syndrome (LEMS), and congenital myasthenic syndromes (CMS) represent an etiologically heterogeneous group of (very) rare chronic diseases. MG and LEMS have an autoimmune-mediated etiology, while CMS are genetic disorders. A (strain dependent) muscle weakness due to neuromuscular transmission disorder is a common feature. Generalized MG requires increasingly differentiated therapeutic strategies that consider the enormous therapeutic developments of recent years. To include the newest therapy recommendations, a comprehensive update of the available German-language guideline 'Diagnostics and therapy of myasthenic syndromes' has been published by the German Neurological society with the aid of an interdisciplinary expert panel. This paper is an adapted translation of the updated and partly newly developed treatment guideline. It defines the rapid achievement of complete disease control in myasthenic patients as a central treatment goal. The use of standard therapies, as well as modern immunotherapeutics, is subject to a staged regimen that takes into account autoantibody status and disease activity. With the advent of modern, fast-acting immunomodulators, disease activity assessment has become pivotal and requires evaluation of the clinical course, including severity and required therapies. Applying MG-specific scores and classifications such as Myasthenia Gravis Activities of Daily Living, Quantitative Myasthenia Gravis, and Myasthenia Gravis Foundation of America allows differentiation between mild/moderate and (highly) active (including refractory) disease. Therapy decisions must consider age, thymic pathology, antibody status, and disease activity. Glucocorticosteroids and the classical immunosuppressants (primarily azathioprine) are the basic immunotherapeutics to treat mild/moderate to (highly) active generalized MG/young MG and ocular MG. Thymectomy is indicated as a treatment for thymoma-associated MG and generalized MG with acetylcholine receptor antibody (AChR-Ab)-positive status. In (highly) active generalized MG, complement inhibitors (currently eculizumab and ravulizumab) or neonatal Fc receptor modulators (currently efgartigimod) are recommended for AChR-Ab-positive status and rituximab for muscle-specific receptor tyrosine kinase (MuSK)-Ab-positive status. Specific treatment for myasthenic crises requires plasmapheresis, immunoadsorption, or IVIG. Specific aspects of ocular, juvenile, and congenital myasthenia are highlighted. The guideline will be further developed based on new study results for other immunomodulators and biomarkers that aid the accurate measurement of disease activity.

Ravulizumab in Myasthenia Gravis: A Review of the Current Evidence

The terminal complement C5 inhibitor ravulizumab was engineered from the humanized monoclonal antibody eculizumab to have an extended half-life and duration of action. It binds to human terminal complement protein C5, inhibiting its cleavage into C5a and C5b, thus preventing the cascade of events that lead to architectural destruction of the postsynaptic neuromuscular junction membrane by the membrane attack complex, and consequent muscle weakness in patients with anti-acetylcholine receptor (AChR) antibody-positive generalized myasthenia gravis (gMG). The 26-week randomized, placebo-controlled period (RCP) of the phase 3 CHAMPION MG study demonstrated the rapid efficacy of ravulizumab in reducing MG symptoms. Weight-based dosing of ravulizumab every 8 weeks provided sustained efficacy, in terms of patient-reported (Myasthenia Gravis-Activities of Daily Living) and clinician-reported (Quantitative Myasthenia Gravis) endpoints in patients with anti-AChR antibody-positive gMG. Pharmacokinetic and pharmacodynamic analyses showed therapeutic serum ravulizumab concentrations (>175 µg/mL) were achieved immediately after the first dose and were maintained throughout 26 weeks, irrespective of patient body weight; inhibition of serum free C5 was immediate, complete (<0.5 μg/mL), and sustained in all patients. Interim results from the open-label extension (OLE) showed that after 60 weeks, efficacy was maintained in patients continuing on ravulizumab. Rapid and sustained improvements in efficacy, similar to those seen in patients initiating ravulizumab in the RCP, were observed after initiation of ravulizumab treatment in patients who switched from placebo in the RCP to ravulizumab in the OLE. The findings from the RCP and OLE support ravulizumab's favorable safety profile. In conclusion, ravulizumab has a simple weight-based administration and long dosing interval. Its targeted mechanism of action without generalized immunosuppression is reflected in its rapid onset of symptom improvement, sustained efficacy and good safety profile in the treatment of patients with anti-AChR antibody-positive gMG.

Efficacy of innovative therapies in myasthenia gravis: A systematic review, meta-analysis and network meta-analysis

BACKGROUND AND PURPOSE

Therapy for myasthenia gravis (MG) is undergoing a profound change, with new treatments being tested. These include complement inhibitors and neonatal Fc receptor (FcRn) blockers. The aim of this study was to perform a meta-analysis and network meta-analysis of randomized and placebo-controlled trials of innovative therapies in MG with available efficacy data.

METHODS

We assessed statistical heterogeneity across trials based on the Cochrane Q test and I2 values, and mean differences were pooled using the random-effects model. Treatment efficacy was assessed after 26 weeks of eculizumab and ravulizumab, 28 days of efgartigimod, 43 days of rozanolixizumab, 12 weeks of zilucoplan, and 16, 24 or 52 weeks of rituximab treatment.

RESULTS

We observed an overall mean Myasthenia Gravis-Activities of Daily Living scale (MG-ADL) score change of -2.17 points (95% confidence interval [CI] -2.67, -1.67; p < 0.001) as compared to placebo. No significant difference emerged between complement inhibitors and anti-FcRn treatment (p = 0.16). The change in Quantitative Myasthenia Gravis scale (QMG) score was -3.46 (95% CI -4.53, -2.39; p < 0.001), with a higher reduction with FcRns (-4.78 vs. -2.60; p < 0.001). Rituximab did not significantly improve the MG-ADL (-0.92 [95% CI -2.24, 0.39]; p = 0.17) or QMG scores (-1.9 [95% CI -3.97, 0.18]; p = 0.07). In the network meta-analysis, efgartigimod had the highest probability of being the best treatment, followed by rozanolixizumab.

CONCLUSION

Anti-complement and FcRn treatments both proved to be effective in MG patients, whereas rituximab did not show a significant benefit for patients. Within the limitations of this meta-analysis, including efficacy time points, FcRn treatments showed a greater effect on QMG score in the short term. Real-life studies with long-term measurements are needed to confirm our results.

Refractory generalized myasthenia gravis with myasthenic incomplete ophthalmoplegia successfully treated with eculizumab

Purpose

This is a case of myasthenic incomplete ophthalmoplegia mimicking a partial cranial nerve 3 palsy both subjectively and objectively improving after treatment with eculizumab.

Observations

We chronicle a case of severe generalized myasthenia gravis including myasthenia masquerading as a partial cranial nerve 3 palsy, refractory to pyridostigmine, mycophenolate, prednisone, intravenous immunoglobulin and plasma exchange but responsive to eculizumab.

Conclusions and importance

This case demonstrates ocular and generalized myasthenia gravis refractory to several other therapies but amenable to eculizumab infusions, suggesting this medication may be of significant value in these difficult cases, and should be further explored for refractory ocular myasthenia gravis.

Study on the Treatment of ITP Mice with IVIG Sourced from Distinct Sex-Special Plasma (DSP-IVIG)

Intravenous immunoglobulin (IVIG) is a first-line drug prepared from human plasma for the treatment of autoimmune diseases (AIDs), especially immune thrombocytopenia (ITP). Significant differences exist in protein types and expression levels between male and female plasma, and the prevalence of autoimmune diseases varies between sexes. The present study seeks to explore potential variations in IVIG sourced from distinct sex-specific plasma (DSP-IVIG), including IVIG sourced from female plasma (F-IVIG), IVIG sourced from male plasma (M-IVIG), and IVIG sourced from a blend of male and female plasma (Mix-IVIG). To address this question, we used an ITP mouse model and a monocyte-macrophage inflammation model treated with DSP IVIG. The analysis of proteomics in mice suggested that the pathogenesis and treatment of ITP may involve FcγRs mediated phagocytosis, apoptosis, Th17, cytokines, chemokines, and more. Key indicators, including the mouse spleen index, CD16+ macrophages, M1, M2, IL-6, IL-27, and IL-13, all indicated that the efficacy in improving ITP was highest for M-IVIG. Subsequent cell experiments revealed that M-IVIG exhibited a more potent ability to inhibit monocyte phagocytosis. It induced more necrotic M2 cells and fewer viable M2, resulting in weaker M2 phagocytosis. M-IVIG also demonstrated superiority in the downregulation of surface makers CD36, CD68, and CD16 on M1 macrophages, a weaker capacity to activate complement, and a stronger binding ability to FcγRs on the THP-1 surface. In summary, DSP-IVIG effectively mitigated inflammation in ITP mice and monocytes and macrophages. However, M-IVIG exhibited advantages in improving the spleen index, regulating the number and typing of M1 and M2 macrophages, and inhibiting macrophage-mediated inflammation compared to F-IVIG and Mix-IVIG.

Impact of Ravulizumab on Patient Outcomes and Quality of Life in Generalized Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune ion channel disorder in which antibodies to different end-plate antigens impair neuromuscular transmission, ultimately leading to muscle weakness and fatigability. In about 85% of patients with MG, autoantibodies against the acetylcholine receptor (AChR) activate the complement cascade, causing damage to the neuromuscular junction. MG is a chronic disorder for which standard therapies with corticosteroids, immunosuppressive drugs, and immunomodulation with plasma exchange or intravenous immunoglobulins modify the course of the disease, but the residual burden of physical, psychological, and social disability highlights several unmet needs, among these the need for specific, targeted, and well tolerated therapies able to improve the patients' quality of life. Complement inhibition paved the way to precision medicine in MG since, for the first time, a specific therapy targeting a crucial pathogenetic step has been designed, tested, and proven to be effective in a controlled fashion. Ravulizumab represents the first long-acting complement inhibitor approved for treatment of patients with generalized MG, able to provide rapid, complete, and sustained complement inhibition. Ravulizumab improved the MG Activity of Daily Living scale and other clinical parameters up to 26 weeks as shown by the CHAMPION MG trial, and by its open label extension, with the added value of being administered every 8 weeks. The schedule of administration is likely to improve patients' adherence and hence their quality of life. The introduction of complement inhibition will considerably change the traditional therapeutic strategy for MG.

Role of complement in myasthenia gravis

Myasthenia gravis is a prototypic neuroimmune disorder with autoantibodies targeting the acetylcholine receptor complex at the neuromuscular junction. Patients present with mainly ocular muscle weakness and tend to have a generalized muscle weakness later in the clinical course. The weakness can be severe and fatal when bulbar muscles are heavily involved. Acetylcholine receptor antibodies are present in the majority of patients and are of IgG1 and IgG3 subtypes which can activate the complement system. The complement involvement plays a major role in the neuromuscular junction damage and the supporting evidence in the literature is described in this article. Complement therapies were initially studied and approved for paroxysmal nocturnal hemoglobinuria and in the past decade, those have also been studied in myasthenia gravis. The currently available randomized control trial and real-world data on the efficacy and safety of the approved and investigational complement therapies are summarized in this review.

Individual myasthenia gravis autoantibody clones can efficiently mediate multiple mechanisms of pathology

Serum autoantibodies targeting the nicotinic acetylcholine receptor (AChR) in patients with autoimmune myasthenia gravis (MG) can mediate pathology via three distinct molecular mechanisms: complement activation, receptor blockade, and antigenic modulation. However, it is unclear whether multi-pathogenicity is mediated by individual or multiple autoantibody clones. Using an unbiased B cell culture screening approach, we generated a library of 11 human-derived AChR-specific recombinant monoclonal autoantibodies (mAb) and assessed their binding properties and pathogenic profiles using specialized cell-based assays. Five mAbs activated complement, three blocked α-bungarotoxin binding to the receptor, and seven induced antigenic modulation. Furthermore, two clonally related mAbs derived from one patient were each highly efficient at more than one of these mechanisms, demonstrating that pathogenic mechanisms are not mutually exclusive at the monoclonal level. Using novel Jurkat cell lines that individually express each monomeric AChR subunit (α2βδε), these two mAbs with multi-pathogenic capacity were determined to exclusively bind the α-subunit of AChR, demonstrating an association between mAb specificity and pathogenic capacity. These findings provide new insight into the immunopathology of MG, demonstrating that single autoreactive clones can efficiently mediate multiple modes of pathology. Current therapeutic approaches targeting only one autoantibody-mediated pathogenic mechanism may be evaded by autoantibodies with multifaceted capacity.

MOGAD patient autoantibodies induce complement, phagocytosis, and cellular cytotoxicity

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is an inflammatory demyelinating CNS condition characterized by the presence of MOG autoantibodies. We sought to investigate whether human MOG autoantibodies are capable of mediating damage to MOG-expressing cells through multiple mechanisms. We developed high-throughput assays to measure complement activity (CA), complement-dependent cytotoxicity (CDC), antibody-dependent cellular phagocytosis (ADCP), and antibody-dependent cellular cytotoxicity (ADCC) of live MOG-expressing cells. MOGAD patient sera effectively mediate all of these effector functions. Our collective analyses reveal that (a) cytotoxicity is not incumbent on MOG autoantibody quantity alone; (b) engagement of effector functions by MOGAD patient serum is bimodal, with some sera exhibiting cytotoxic capacity while others did not; (c) the magnitude of CDC and ADCP is elevated closer to relapse, while MOG-IgG binding is not; and (d) all IgG subclasses can damage MOG-expressing cells. Histopathology from a representative MOGAD case revealed congruence between lesion histology and serum CDC and ADCP, and we identified NK cells, mediators of ADCC, in the cerebrospinal fluid of relapsing patients with MOGAD. Thus, MOGAD-derived autoantibodies are cytotoxic to MOG-expressing cells through multiple mechanisms, and assays quantifying CDC and ADCP may prove to be effective tools for predicting risk of future relapses.

Long-term efficacy and safety of ravulizumab in adults with anti-acetylcholine receptor antibody-positive generalized myasthenia gravis: results from the phase 3 CHAMPION MG open-label extension

INTRODUCTION

Ravulizumab demonstrated efficacy and an acceptable safety profile versus placebo in the randomized controlled period (RCP) of the phase 3 CHAMPION MG trial in patients with anti-acetylcholine receptor antibody-positive generalized myasthenia gravis. We report an interim analysis of the ongoing open-label extension (OLE) designed to evaluate long-term treatment effects.

METHODS

Following completion of the 26-week RCP, patients could enter the OLE; patients who received ravulizumab in the RCP continued the drug; patients who previously received placebo switched to ravulizumab. Patients receive body-weight-based maintenance dosing of ravulizumab every 8 weeks. Efficacy endpoints up to 60 weeks included Myasthenia Gravis-Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) scores, with least-squares (LS) mean change and 95% confidence intervals (95% CI) reported.

RESULTS

Long-term efficacy and safety in the OLE were analyzed in 161 and 169 patients, respectively. Improvements in all scores were maintained through 60 weeks in patients who received ravulizumab during the RCP; LS mean change from RCP baseline in MG-ADL score was - 4.0 (95% CI: - 4.8, - 3.1; p < 0.0001). Rapid (within 2 weeks) and sustained improvements occurred in patients previously receiving placebo; LS mean change in MG-ADL score from OLE baseline to Week 60 was - 1.7 (95% CI: - 2.7, - 0.8; p = 0.0007). Similar trends were seen in QMG scores. Ravulizumab treatment was associated with a decreased rate of clinical deterioration events compared with placebo. Ravulizumab was well tolerated; no meningococcal infections were reported.

CONCLUSION

Findings support the sustained efficacy and long-term safety of ravulizumab, administered every 8 weeks, in adults with anti-acetylcholine receptor antibody-positive generalized myasthenia gravis.

CLINICALTRIALS

gov identifier: NCT03920293; EudraCT: 2018-003243-39.

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.

[Myasthenia in adults, children, and adolescents: what's new?]

Therapy of myasthenia gravis (MG) is increasingly oriented to the patient's antibody status. In addition to symptomatic therapy, steroids, classic long-term immunosuppressive therapies and thymectomy are regularly used. In recent years, new therapeutic approaches have been developed that particularly benefit acetylcholine receptor (AChR) antibody (Abs) positive patients with highly active disease. While the C5 complement inhibitor eculizumab was reserved for treatment-refractory generalized courses of AChR-Abs positive MG, two new drugs, the neonatal Fc receptor inhibitor efgartigimod and the more advanced C5 complement inhibitor ravulizumab, have recently been approved as add-on therapy for AChR-Abs positive generalized MG (gMG). In highly active courses of MG with Abs against the muscle-specific receptor tyrosine kinase (MuSK), the use of rituximab should be considered early in the course of the disease. The efficacy of the new drugs in children and adolescents with juvenile MG (JMG) is currently being tested in clinical trials. The new guideline recommends the use of modern immunomodulators based on a step-by-step approach depending on disease activity. With the German Myasthenia Register (MyaReg), the changing therapeutic landscape and quality of life of patients with myasthenic syndromes can be assessed, thus providing real-world data on the care of MG patients. Despite treatment based on the previous guideline, many MG patients suffer considerable impairment to their quality of life. With the new immunomodulators, there is the possibility of early intensified immunotherapy, which, in contrast to long-term immunosuppressants, can lead to a rapid improvement in the course of the disease.

The case for complement component 5 as a target in neurodegenerative disease

INTRODUCTION

Complement-based drug discovery is undergoing a renaissance, empowered by new advances in structural biology, complement biology and drug development. Certain components of the complement pathway, particularly C1q and C3, have been extensively studied in the context of neurodegenerative disease, and established as key therapeutic targets. C5 also has huge therapeutic potential in this arena, with its druggability clearly demonstrated by the success of C5-inhibitor eculizumab.

AREAS COVERED

We will discuss the evidence supporting C5 as a target in neurodegenerative disease, along with the current progress in developing different classes of C5 inhibitors and the gaps in knowledge that will help progress in the field.

EXPERT OPINION

Validation of C5 as a therapeutic target for neurodegenerative disease would represent a major step forward for complement therapeutics research and has the potential to furnish disease-modifying drugs for millions of patients suffering worldwide. Key hurdles that need to be overcome for this to be achieved are understanding how C5a and C5b should be targeted to bring therapeutic benefit and demonstrating the ability to target C5 without creating vulnerability to infection in patients. This requires greater biological elucidation of its precise role in disease pathogenesis, supported by better chemical/biological tools.

Reduced quality of life in myasthenia gravis patients: A study on 185 patients from China

Aims

To explore the quality of life (QOL) in patients with myasthenia gravis (MG) and factors associated with QOL.

Methods

This observational study included patients with MG diagnosed at the First Affiliated Hospital of Fujian Medical University between January 2020 and March 2022. The QOL of patients was evaluated with the 15-item Myasthenia Gravis Quality of Life (MG-QOL15). Current MG severity was evaluated with MGFA grade, MG-ADL score, MGC score, and MGFA Postintervention Status. The data about gender, age of onset, subgroup, antibodies, age, duration, education, employment state, marital status, skeletal muscle affected, thymic histology, and current treatment methods of the patient were collected.

Results

A total of 185 patients [72 males (38.9%), aged 45.2 years (14-77)] with MG were enrolled. Age at onset was 38.3 ± 17.9 years, and disease duration was 87.9 months (0-672). The median MG-QOL15 score was 12.5 (0-58). The item "have trouble using my eyes" was the highest scoring item in both ocular and generalized patients with MG. The MG-QOL15 score was significantly different among patients with OMG (9.2 ± 9.4, n = 63), GMG (9.0 ± 8.8, n = 22), and BMG (15.4 ± 14.2, n = 100) (P = 0.018). Patients with BMG had higher MG-QOL15 scores than OMG (P = 0.001) and GMG (P = 0.009), but there was no significant difference between OMG and GMG (P = 0.467). The MG-QOL15 score was significantly lower in patients who had undergone thymectomy (9.7 ± 9.8, n = 58) compared to those who had not (13.8 ± 13.4, n = 127, P = 0.022). MG-QOL15 score was significantly lower in patients who underwent thymectomy compared to those who did not (9.7 ± 9.8, n = 58 vs. 13.8 ± 13.4, n = 127, P = 0.022). MG-QOL15 score was different among MGFA grades (Remission: 5.2 ± 5.4, n = 41; I: 11.3 ± 10, n = 61; II: 11.6 ± 11.1, n = 40; III: 18.1 ± 12.1, n = 29; and IVa: 30.1 ± 20, n = 14, P < 0.001). There was no significant difference between patients in MGFA grade I and II (P = 0.896), and there was no significant difference between patients in MGFA grade III and IVa (P = 0.052). MG-ADL (P < 0.001) and MGC (P < 0.001) were positively correlated with MG-QOL15. Men had higher MG-QOL15 than women (P = 0.094), and LOMG had higher MG-QOL15 than EOMG (P = 0.072). Multivariate linear regression identified that higher MG-ADL (P < 0.001), higher MGC (P = 0.02), and poor employment status (P = 0.045) were independently associated with higher MG-QOL15.

Conclusion

Having trouble using the eyes accounted for the highest score in MG-QOL15, eye symptoms affect QOL more than limb weakness in MG. Daily life activity, disease severity, and employment status were associated with patients' QOL. Adequate treatment should be applied to improve QOL, while mild symptoms can be accepted. Men and patients over the age of 50 years of onset may need more attention.

Efgartigimod for generalized myasthenia gravis with or without anti-acetylcholine receptor antibodies: a worldwide and Japanese perspective

INTRODUCTION

The management of myasthenia gravis (MG) has been improved due to immunotherapy advances, but 20% of individuals with MG are refractory to the conventional therapy, and the need for novel biological drugs remains.

AREA COVERED

The Japanese clinical guidelines for MG published in May 2022 include the concept that treatment is often lifelong and should aim to maintain a sufficient quality of life and mental health. We provide an overview of the therapeutic strategy for generalized MG in Japan, in comparison with the international consensus. We summarize the clinical efficacy, safety, and tolerability of efgartigimod, the first approved anti-neonatal Fc receptor inhibitor for MG. A phase III study showed that efgartigimod was well-tolerated and efficacious in patients with generalized MG.

EXPERT OPINION

Efgartigimod is a promising biological drug for patients with moderate to severe generalized MG with or without anti-acetylcholine receptor antibodies in Japan.

Receptor clustering and pathogenic complement activation in myasthenia gravis depend on synergy between antibodies with multiple subunit specificities

Myasthenia gravis is an autoimmune disorder defined by muscle weakness and fatigability associated with antibodies against proteins of the neuromuscular junction (NMJ). The most common autoantibody target is the acetylcholine receptor (AChR). Three mechanisms have been postulated by which autoantibodies might interfere with neurotransmission: direct antagonism of the receptor, complement-mediated destruction of the postsynaptic membrane, and enhanced internalization of the receptor. It is very likely that more than one of these mechanisms act in parallel. Dissecting the mechanisms of autoantibody-mediated pathology requires patient-derived, monoclonal antibodies. Using membrane antigen capture activated cell sorting (MACACS), we isolated AChR-specific B cells from patients with myasthenia gravis, and produced six recombinant antibodies. All AChR-specific antibodies were hypermutated, including isotypes IgG1, IgG3, and IgG4, and recognized different subunits of the AChR. Despite clear binding, none of the individual antibodies showed significant antagonism of the AChR measured in an in vitro neuromuscular synapse model, or AChR-dependent complement activation, and they did not induce myasthenic signs in vivo. However, combinations of antibodies induced strong complement activation in vitro, and severe weakness in a passive transfer myasthenia gravis rat model, associated with NMJ destruction and complement activation in muscle. The strongest complement activation was mediated by combinations of antibodies targeting disparate subunits of the AChR, and such combinations also induced the formation of large clusters of AChR on the surface of live cells in vitro. We propose that synergy between antibodies of different epitope specificities is a fundamental feature of this disease, and possibly a general feature of complement-mediated autoimmune diseases. The importance of synergistic interaction between antibodies targeting different subunits of the receptor can explain the well-known discrepancy between serum anti-AChR titers and clinical severity, and has implications for therapeutic strategies currently under investigation.

New Targeted Agents in Myasthenia Gravis and Future Therapeutic Strategies

Myasthenia gravis (MG) is a chronic autoimmune disease for which multiple immunomodulatory therapies are available. Nevertheless, MG has a significant impact on patient quality of life. In recent years, experts' main efforts have focused on optimizing treatment strategies, since disease burden is considerably affected by their safety and tolerability profiles, especially in patients with refractory phenotypes. This article aims to offer neurologists caring for MG patients an overview of the most innovative targeted drugs specifically designed for this disease and summarizes the recent literature and more recent evidence on agents targeting B cells and plasmablasts, complement inhibitors, and neonatal fragment crystallizable receptor (FcRn) antagonists. Positive clinical trial results have been reported, and other studies are ongoing. Finally, we briefly discuss how the introduction of these novel targeted immunological therapies in a changing management paradigm would affect not only clinical outcomes, disease burden, safety, and tolerability, but also health spending in a condition that is increasingly managed based on a patient-centred model.

Systems biology and artificial intelligence analysis highlights the pleiotropic effect of IVIg therapy in autoimmune diseases with a predominant role on B cells and complement system

Intravenous immunoglobulin (IVIg) is used as treatment for several autoimmune and inflammatory conditions, but its specific mechanisms are not fully understood. Herein, we aimed to evaluate, using systems biology and artificial intelligence techniques, the differences in the pathophysiological pathways of autoimmune and inflammatory conditions that show diverse responses to IVIg treatment. We also intended to determine the targets of IVIg involved in the best treatment response of the evaluated diseases. Our selection and classification of diseases was based on a previously published systematic review, and we performed the disease characterization through manual curation of the literature. Furthermore, we undertook the mechanistic evaluation with artificial neural networks and pathway enrichment analyses. A set of 26 diseases was selected, classified, and compared. Our results indicated that diseases clearly benefiting from IVIg treatment were mainly characterized by deregulated processes in B cells and the complement system. Indeed, our results show that proteins related to B-cell and complement system pathways, which are targeted by IVIg, are involved in the clinical response. In addition, targets related to other immune processes may also play an important role in the IVIg response, supporting its wide range of actions through several mechanisms. Although B-cell responses and complement system have a key role in diseases benefiting from IVIg, protein targets involved in such processes are not necessarily the same in those diseases. Therefore, IVIg appeared to have a pleiotropic effect that may involve the collaborative participation of several proteins. This broad spectrum of targets and 'non-specificity' of IVIg could be key to its efficacy in very different diseases.

Practical Management for Use of Eculizumab in the Treatment of Severe, Refractory, Non-Thymomatous, AChR + Generalized Myasthenia Gravis: A Systematic Review

Myasthenia gravis (MG) is a rare autoimmune disorder caused by specific autoantibodies at the neuromuscular junction. MG is classified by the antigen specificity of these antibodies. Acetylcholine receptor (AChR) antibodies are the most common type (74–88%), followed by anti-muscle specific kinase (MuSK) and other antibodies. While all these antibodies lead to neuromuscular transmission failure, the immuno-pathogenic mechanisms are distinct. Complement activation is a primary driver of AChR antibody-positive MG (AChR+ MG) pathogenesis. This leads to the formation of the membrane attack complex and destruction of AChR receptors and the postsynaptic membrane resulting in impaired neurotransmission and muscle weakness characteristic of MG. Broad-based immune-suppressants like corticosteroids are effective in controlling MG; however, their long-term use can be associated with significant adverse effects. Advances in translational research have led to the development of more directed therapeutic agents that are likely to alter the future of MG treatment. Eculizumab is a humanized monoclonal antibody that inhibits the cleavage of complement protein C5 and is approved for use in generalized MG. In this review, we discuss the pathophysiology of MG; the therapeutic efficacy and tolerability of eculizumab, as well as the practical guidelines for its use in MG; future studies exploring the role of eculizumab in different stages and subtypes of MG subtypes; the optimal duration of therapy and its discontinuation; the characterization of non-responder patients; and the use of biomarkers for monitoring therapy are highlighted. Based on the pathophysiologic mechanisms, emerging therapies and new therapeutic targets are also reviewed.

Heterogeneity of Acetylcholine Receptor Autoantibody-Mediated Complement Activity in Patients With Myasthenia Gravis

BACKGROUND AND OBJECTIVES

Autoantibodies targeting the acetylcholine receptor (AChR), found in patients with myasthenia gravis (MG), mediate pathology through 3 mechanisms: complement-directed tissue damage, blocking of the acetylcholine binding site, and internalization of the AChR. Clinical assays, used to diagnose and monitor patients, measure only autoantibody binding. Consequently, they are limited in providing association with disease burden, understanding of mechanistic heterogeneity, and monitoring therapeutic response. The objective of this study was to develop a cell-based assay that measures AChR autoantibody-mediated complement membrane attack complex (MAC) formation.

METHODS

An HEK293T cell line-modified using CRISPR/Cas9 genome editing to disrupt expression of the complement regulator genes (CD46, CD55, and CD59)-was used to measure AChR autoantibody-mediated MAC formation through flow cytometry.

RESULTS

Serum samples (n = 155) from 96 clinically confirmed AChR MG patients, representing a wide range of disease burden and autoantibody titer, were tested along with 32 healthy donor (HD) samples. AChR autoantibodies were detected in 139 of the 155 (89.7%) MG samples through a cell-based assay. Of the 139 AChR-positive samples, autoantibody-mediated MAC formation was detected in 83 (59.7%), whereas MAC formation was undetectable in the HD group or AChR-positive samples with low autoantibody levels. MAC formation was positively associated with autoantibody binding in most patient samples; ratios (mean fluorescence intensity) of MAC formation to AChR autoantibody binding ranged between 0.27 and 48, with a median of 0.79 and an interquartile range of 0.43 (0.58-1.1). However, the distribution of ratios was asymmetric and included extreme values; 16 samples were beyond the 10-90 percentile, with high MAC to low AChR autoantibody binding ratio or the reverse. Correlation between MAC formation and clinical disease scores suggested a modest positive association (rho = 0.34, p = 0.0023), which included a subset of outliers that did not follow this pattern. MAC formation did not associate with exposure to immunotherapy, thymectomy, or MG subtypes defined by age-of-onset.

DISCUSSION

A novel assay for evaluating AChR autoantibody-mediated complement activity was developed. A subset of patients that lacks association between MAC formation and autoantibody binding or disease burden was identified. The assay may provide a better understanding of the heterogeneous autoantibody molecular pathology and identify patients expected to benefit from complement inhibitor therapy.