Treatment of refractory myasthenia: "rebooting" with high-dose cyclophosphamide

Optimization of the cut-offs in acetylcholine receptor antibodies and diagnostic performance in myasthenia gravis patients

OBJECTIVE

This study aims to establish an optimization procedure to define the cut-offs of quantitative assays for acetylcholine receptor antibody (AChRAb), evaluate their diagnostic performance in myasthenia gravis (MG), and explore the association with clinical features.

METHODS

Samples from a representative cohort of 77 MG patients, 80 healthy controls (HC) and 80 other autoimmune diseases (OAD) patients were tested using competitive inhibition ELISA and RIA. Raw values (OD and cpm) and processed values (inhibition rate, binding rate and concentration) were used to define the cut-offs with statistical methods, a rough method, and receiver operating characteristic (ROC) curve. Optimal cut-offs were selected by comparing false positive rates in HC and OAD individuals. The diagnostic performance was evaluated in whole MG cohort and subgroups. Agreement between ELISA and RIA for AChRAb positivity were examined with Kappa test and McNemar test. Clinical association with AChRAb was explored by comparison among subgroups and with Spearman rank correlation.

RESULTS

The optimal cut-offs for AChRAb positivity were determined as OD≤1.79 for ELISA and cpm≥1234.12 for RIA, which derived from statistical method and performed better than those derived from ROC curves. The sensitivity and specificity were 74.03%, 100% for ELISA, and 74.03%, 99.37% for RIA. There was good agreement between ELISA and RIA for AChRAb positivity in whole cohort and subgroups (weighted к ≥0.71, p<0.01; McNemar test, p>0.05). Levels of AChRAb were different in MG subgroups (p<0.01). Correlation between Quantitative Myasthenia Gravis scores and AChRAb levels was moderate for ELISA and RIA (r_s=-0.60 and 0.57, p<0.01).

CONCLUSION

The raw testing values of ELISA and RIA were found as optimal quantitative measures of AChRAb levels. There are good agreements on diagnostic performance between two assays. Quantitative values are more informative than positivity in association with clinical features.

Novel treatment strategies for acetylcholine receptor antibody-positive myasthenia gravis and related disorders

The presence of autoantibodies directed against the muscle nicotinic acetylcholine receptor (AChR) is the most common cause of myasthenia gravis (MG). These antibodies damage the postsynaptic membrane of the neuromuscular junction and cause muscle weakness by depleting AChRs and thus impairing synaptic transmission. As one of the best-characterized antibody-mediated autoimmune diseases, AChR-MG has often served as a reference model for other autoimmune disorders. Classical pharmacological treatments, including broad-spectrum immunosuppressive drugs, are effective in many patients. However, complete remission cannot be achieved in all patients, and 10% of patients do not respond to currently used therapies. This may be attributed to production of autoantibodies by long-lived plasma cells which are resistant to conventional immunosuppressive drugs. Hence, novel therapies specifically targeting plasma cells might be a suitable therapeutic approach for selected patients. Additionally, in order to reduce side effects of broad-spectrum immunosuppression, targeted immunotherapies and symptomatic treatments will be required. This review presents established therapies as well as novel therapeutic approaches for MG and related conditions, with a focus on AChR-MG.

Current Treatment of Myasthenia Gravis

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

Current pharmacotherapeutic options for myasthenia gravis

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

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

Background:

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

Methods:

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

Results:

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

Conclusions:

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

Treatment of Myasthenia Gravis

With specialized care, patients with myasthenia gravis can have very good outcomes. The mainstays of treatment are acetylcholinesterase inhibitors, and immunosuppressive and immunomodulatory therapies. There is good evidence thymectomy is beneficial in thymomatous and nonthymomatous disease. Nearly all of the drugs used for MG are considered "off-label." The 2 exceptions are acetylcholinesterase inhibitors and complement inhibition with eculizumab, which was recently approved by the US Food and Drug Administration for myasthenia gravis. This article reviews the evidence base and provides a framework for the treatment of myasthenia gravis, highlighting recent additions to the literature.

Molecular mechanism involved in cyclophosphamide-induced cardiotoxicity: Old drug with a new vision

Cyclophosphamide (CP) is an important anticancer drug which belongs to the class of alkylating agent. Cyclophosphamide is mostly used in bone marrow transplantation, rheumatoid arthritis, lupus erythematosus, multiple sclerosis, neuroblastoma and other types of cancer. Dose-related cardiotoxicity is a limiting factor for its use. CP-induced cardiotoxicity ranges from 7 to 28% and mortality ranges from 11 to 43% at the therapeutic dose of 170-180 mg/kg, i.v. CP undergoes hepatic metabolism that results in the production of aldophosphamide. Aldophosphamide decomposes into phosphoramide mustard & acrolein. Phosphoramide is an active neoplastic agent, and acrolein is a toxic metabolite which acts on the myocardium and endothelial cells. This is the first review article that talks about cyclophosphamide-induced cardiotoxicity and the different signaling pathways involved in its pathogenicity. Based on the available literature, CP is accountable for cardiomyocytes energy pool alteration by affecting the heart fatty acid binding proteins (H-FABP). CP has been found associated with cardiomyocytes apoptosis, inflammation, endothelial dysfunction, calcium dysregulation, endoplasmic reticulum damage, and mitochondrial damage. Molecular mechanism of cardiotoxicity has been discussed in detail through crosstalk of Nrf2/ARE, Akt/GSK-3β/NFAT/calcineurin, p53/p38MAPK, NF-kB/TLR-4, and Phospholamban/SERCA-2a signaling pathway. Based on the available literature we support the fact that metabolites of CP are responsible for cardiotoxicity due to depletion of antioxidants/ATP level, altered contractility, damaged endothelium and enhanced pro-inflammatory/pro-apoptotic activities resulting into cardiomyopathy, myocardial infarction, and heart failure. Dose adjustment, elimination/excretion of acrolein and maintenance of endogenous antioxidant pool could be the therapeutic approach to mitigate the toxicities.

When myasthenia gravis is deemed refractory: clinical signposts and treatment strategies

The prognosis for patients with myasthenia gravis (MG) has improved significantly over the past half century, including substantial reductions in mortality and morbidity. However, approximately 10% of patients fails to respond adequately to current therapies and are considered treatment refractory, or treatment intolerant, and up to 80% have disease that fails to achieve complete stable remission. Although patients with autoantibodies to muscle-specific tyrosine kinase (anti-MuSK positive) are more likely to become treatment refractory than those with autoantibodies to the acetylcholine receptor (anti-AChR positive), each of these serotypes is substantially represented in the refractory MG population. Other risk factors for becoming treatment refractory include history of thymoma or thymectomy and female sex. A modified treatment algorithm for MG is proposed: patients who have disease that fails to respond to the stepwise approach to therapy, are treatment intolerant, or who require chronic rescue measures despite ongoing therapy, should be considered treatment refractory and emerging therapies should be considered. Three emerging monoclonal antibody-based therapies are discussed: the anti-B-cell agent rituximab; the terminal complement activation inhibitor eculizumab; and belimumab, which targets B-cell activating factor. Increased understanding of molecular pathophysiology and accurate antibody subtyping in MG should lead to the use of new therapeutic agents and successful management of treatment-refractory patients.

Docetaxel/cisplatin Therapy in Myasthenia Gravis with Hypertension/diabetes

Background

Therapeutic options for thymoma-associated myasthenia gravis (MG) patients complicated with hypertension and/or diabetes post thymectomy are often conventional steroids. As the prevalence of diabetes and hypertension globally increases, other therapeutic options for these patients are of great importance.

Material/methods

9 patients with thymoma-associated MG complicated with hypertension and/or diabetes after thymectomy were administered 75 mg/m2 of docetaxel and 70 mg/m2 of cisplatin on day 1. The treatment could be repeated at 3-week intervals, ranging from 1 to 4 cycles according to the status of the patients. Therapeutic efficacy and side effects were evaluated.

Results

2 patients were complicated with type 2 diabetes, 6 with hypertension, and 1 with both diabetes and hypertension. After docetaxel/cisplain therapy, the MG symptoms were markedly improved in all patients (2, complete remission; 3, basic remission; 3, marked improvement; 1, improvement). Acetylcholine receptor (AchR) antibody levels were decreased in 8 patients. Minor adverse effects were observed in 2 patients, 1 with Grade II gastrointestinal reaction, and the other with pulmonary infection.

Conclusion

Docetaxel plus cisplatin might be an effective therapeutic option for thymoma-associated MG patients complicated with hypertension /diabetes post thymectomy without worsening thymoma and hypertension / diabetes.

Neurotherapeutic Strategies for Multiple Sclerosis

Multiple sclerosis (MS) is the most common disabling neurologic disease of young adults. There are now 16 US Food and Drug Administration (FDA)-approved disease-modifying therapies for MS as well as a cohort of other agents commonly used in practice when conventional therapies prove inadequate. This article discusses approved FDA therapies as well as commonly used practice-based therapies for MS, as well as those therapies that can be used in patients attempting to become pregnant, or in patients with an established pregnancy, who require concomitant treatment secondary to recalcitrant disease activity.

Neuromuscular junction disorders

Diseases of the neuromuscular junction comprise a wide range of disorders. Antibodies, genetic mutations, specific drugs or toxins interfere with the number or function of one of the essential proteins that control signaling between the presynaptic nerve ending and the postsynaptic muscle membrane. Acquired autoimmune disorders of the neuromuscular junction are the most common and are described here. In myasthenia gravis, antibodies to acetylcholine receptors or to proteins involved in receptor clustering, particularly muscle-specific kinase, cause direct loss of acetylcholine receptors or interfere with the agrin-induced acetylcholine receptor clustering necessary for efficient neurotransmission. In the Lambert-Eaton myasthenic syndrome (LEMS), loss of the presynaptic voltage-gated calcium channels results in reduced release of the acetylcholine transmitter. The conditions are generally recognizable clinically and the diagnosis confirmed by serologic testing and electromyography. Screening for thymomas in myasthenia or small cell cancer in LEMS is important. Fortunately, a wide range of symptomatic treatments, immunosuppressive drugs, or other immunomodulating therapies is available. Future research is directed to understanding the pathogenesis, discovering new antigens, and trying to develop disease-specific treatments.

Clinical features, pathogenesis, and treatment of myasthenia gravis: a supplement to the Guidelines of the German Neurological Society

Myasthenia gravis (MG) is an autoimmune antibody-mediated disorder of neuromuscular synaptic transmission. The clinical hallmark of MG consists of fluctuating fatigability and weakness affecting ocular, bulbar and (proximal) limb skeletal muscle groups. MG may either occur as an autoimmune disease with distinct immunogenetic characteristics or as a paraneoplastic syndrome associated with tumors of the thymus. Impairment of central thymic and peripheral self-tolerance mechanisms in both cases is thought to favor an autoimmune CD4(+) T cell-mediated B cell activation and synthesis of pathogenic high-affinity autoantibodies of either the IgG1 and 3 or IgG4 subclass. These autoantibodies bind to the nicotinic acetylcholine receptor (AchR) itself, or muscle-specific tyrosine-kinase (MuSK), lipoprotein receptor-related protein 4 (LRP4) and agrin involved in clustering of AchRs within the postsynaptic membrane and structural maintenance of the neuromuscular synapse. This results in disturbance of neuromuscular transmission and thus clinical manifestation of the disease. Emphasizing evidence from clinical trials, we provide an updated overview on immunopathogenesis, and derived current and future treatment strategies for MG divided into: (a) symptomatic treatments facilitating neuromuscular transmission, (b) antibody-depleting treatments, and

Precision medicine in myasthenia graves: begin from the data precision

Myasthenia gravis (MG) is a prototypic autoimmune disease with overt clinical and immunological heterogeneity. The data of MG is far from individually precise now, partially due to the rarity and heterogeneity of this disease. In this review, we provide the basic insights of MG data precision, including onset age, presenting symptoms, generalization, thymus status, pathogenic autoantibodies, muscle involvement, severity and response to treatment based on references and our previous studies. Subgroups and quantitative traits of MG are discussed in the sense of data precision. The role of disease registries and scientific bases of precise analysis are also discussed to ensure better collection and analysis of MG data.

Current and future immunotherapy targets in autoimmune neurology

Randomized controlled treatment trials of autoimmune neurologic disorders are generally lacking and data pertaining to treatment are mostly derived from expert opinion, large case series, and anecdotal reports. The treatment of autoimmune neurologic disorders comprises oncologic therapy (where appropriate) and immunotherapy. In this chapter, we first describe the standard acute and chronic immunotherapies and provide a practical overview of their use in the clinic (mechanisms of action, dosing, monitoring, and side effects). Novel approaches to treatment of autoimmune neurologic disorders, through new drug discovery or repurposing, are dependent on improved mechanistic understanding of immunopathology. Such approaches, with emphasis on monoclonal antibodies, are discussed using the paradigm of three autoimmune neurologic disorders whose immunopathogenesis is better understood, specifically myasthenia gravis, neuromyelitis optica, and chronic inflammatory demyelinating polyradiculoneuropathy. It is important to realize that the treatment strategy and management plan must be individualized for each patient. In general these are influenced by the following: clinical severity, antibody type, presence or absence of cancer, and prior treatment response, if known.

Treatment-refractory myasthenia gravis

Myasthenia gravis (MG) is the most common disorder of neuromuscular transmission and is a prototypical autoimmune disorder. Most patients with MG are successfully treated with acetylcholinesterase inhibitors, corticosteroids, and/or steroid sparing agents such as azathioprine and mycophenolate mofetil. There is a small subset of patients, however, with treatment-refractory disease. In these cases, medications such as rituximab, high-dose cyclophosphamide, and eculizumab may be used. Thymectomy (in some cases repeat thymectomy) is another option in selected patients. Studies evaluating these and other forms of therapy in treatment-refractory MG are reviewed.

Multiple sclerosis and cancer: when two wrongs make a right?

INTRODUCTION

Current treatments for multiple sclerosis (MS) remain partially successful, with certain patients remaining treatment resistant. A recent treatment, known as 'immunoablation' has been used in severe cases of adult MS with promising results. However, due to its high risk and reservation for severe or refractory cases, its full potential remains unknown.

METHODS

We report the case of MM, a 14-year-old boy diagnosed with MS and a concurrent diagnosis of Hodgkin's lymphoma.

RESULTS

After receiving aggressive chemotherapy (immunoablation) for Hodgkin's lymphoma, MM's MS symptoms appear to have remitted, and he has remained progression- and disease activity-free for over six years.

DISCUSSION

This case study will focus on MM's cognitive and behavioural development over this time, but will also discuss treatment implications raised by this rare case.

Myasthenia gravis: an update for the clinician

This paper provides a thorough overview of the current advances in diagnosis and therapy of myasthenia gravis (MG). Nowadays the term 'myasthenia gravis' includes heterogeneous autoimmune diseases, with a postsynaptic defect of neuromuscular transmission as the common feature. Myasthenia gravis should be classified according to the antibody specificity [acetylcholine, muscle-specific receptor tyrosine kinase (MuSK), low-density lipoprotein receptor-related protein 4 (LRP4), seronegative], thymus histology (thymitis, thymoma, atrophy), age at onset (in children; aged less than or more than 50 years) and type of course (ocular or generalized). With optimal treatment, the prognosis is good in terms of daily functions, quality of life and survival. Symptomatic treatment with acetylcholine esterase inhibition is usually combined with immunosuppression. Azathioprine still remains the first choice for long-term immunosuppressive therapy. Alternative immunosuppressive options to azathioprine include cyclosporin, cyclophosphamide, methotrexate, mycophenolate mofetil and tacrolimus. Rituximab is a promising new drug for severe generalized MG. Emerging therapy options include belimumab, eculizumab and the granulocyte- macrophage colony-stimulating factor. One pilot study on etanercept has given disappointing results. For decades, thymectomy has been performed in younger adults to improve non-paraneoplastic MG. However, controlled prospective studies on the suspected benefit of this surgical procedure are still lacking. In acute exacerbations, including myasthenic crisis, intravenous immunoglobulin, plasmapheresis and immunoadsorption are similarly effective.

Efficacy and limitations of pulse cyclophosphamide therapy in polymyositis and dermatomyositis

OBJECTIVES

To assess the therapeutic response of intravenous (IV) pulse cyclophosphamide therapy in polymyositis and dermatomyositis.

METHODS

Data of 9 patients (M:F = 2:7) who received IV pulse cyclophosphamide therapy were retrospectively analyzed.

RESULTS

The mean symptom duration was 11.33 ± 10.6 months (range, 2-34 months). The cohort comprised (1) primary idiopathic polymyositis (n = 1), (2) primary idiopathic dermatomyositis (n = 1), (3) childhood type associated with vasculitis (n = 1), and (4) associated with collagen vascular disease (n = 6). All patients improved and became clinically asymptomatic after a mean period of 12.33 ± 6.5 months (range, 4-24 months); 5 remained asymptomatic at the end of a median follow-up period of 22 months. All patients received concomitant steroid therapy, and in 6, steroids could be tapered after the initiation of IV pulse cyclophosphamide therapy.

CONCLUSIONS

In this cohort of polymyositis/dermatomyositis, treatment with IV pulse cyclophosphamide was associated with improvement; the therapeutic response was sustained in majority of the patients.

Management challenges in muscle-specific tyrosine kinase myasthenia gravis

Myasthenia gravis with antibodies to muscle-specific tyrosine kinase (MuSK-MG) is generally considered a severe disease because of the associated weakness distribution with prevalent involvement of bulbar muscles and a rapidly progressive course and early respiratory crises. Its treatment can be unrewarding, owing to poor response to acetylcholinesterase inhibitors in most patients, disease relapses in spite of high-dose immunosuppression, and development of permanent bulbar weakness. High-dose prednisone plus plasma exchange is the recommended approach for treating rapidly progressive bulbar weakness. In the disease management, oral steroids proved effective, plasma exchange produced marked, albeit short-term, improvement, while conventional immunosuppressants were comparatively less effective. Rituximab is a promising treatment for refractory MuSK-MG; in uncontrolled studies, nearly all treated patients achieved significant improvement with substantial decrease of medication. It is yet to be clarified whether the early use of rituximab could prevent the permanent bulbar weakness, which constitutes a relevant disability in these patients.

Diagnosis and therapy of myasthenia gravis with antibodies to muscle-specific kinase

Myasthenia gravis (MG) with antibodies to the muscle-specific receptor tyrosine kinase (MuSK-MG) is a rare disease which covers 5-8% of all MG patients. Symptoms are nearly always generalized, though more focal than in MG with anti-acetylcholine receptor antibodies, with predominant involvement of cranial, bulbar and axial muscles; early respiratory crises are frequent. Focal atrophy, mostly of facial, masseter and tongue muscles, occurs in a proportion of patients. Diagnosis is often challenging on account of atypical presentation with little or no symptom fluctuations, lack of response to acetylcholinesterase inhibitors in a high proportion of patients and negative results of electrodiagnostic studies when performed on limb muscles. Immunosuppression is the mainstay of treatment, since the response to acetylcholinesterase inhibitors is generally unsatisfactory and thymectomy does not appear to improve the course of the disease. Although corticosteroids result in marked improvement, disease flares are frequent during prednisone dosage tapering and most patients remain dependent on treatment. Since treatment with rituximab, in uncontrolled studies, induced sustained benefit in patients with refractory disease, B cell depletion is an attractive option for MuSK-MG patients unresponsive to conventional immunosuppressants.

Phase II trial of methotrexate in myasthenia gravis

Prednisone is a frequently used treatment for myasthenia gravis (MG) but it has numerous side effects. Methotrexate is a selective inhibitor of dihydrofolate reductase and lymphocyte proliferation and is an effective immuosuppressive medication for autoimmune diseases. Given the negative results of the mycophenolate mofetil study, search for an effective immunosuppressant drug therapy is ongoing. The objective is to determine if oral methotrexate is safe and effective for MG patients who take prednisone. We have initiated a randomized, double-blind, placebo-controlled multicenter trial of methotrexate versus placebo in patients taking at least 10 mg/day of prednisone at enrollment. The methotrexate dose is increased to 20 mg and the prednisone dose is adjusted per protocol during the study. Clinical and laboratory evaluations are performed monthly for 12 months, with the primary efficacy measure being the nine-month prednisone area under the curve (AUC) from months 3 to 12. Secondary outcome measures include MG outcomes, quality of life measures, and a polyglutamation biomarker assay. A total of 18 U.S. sites and 2 Canadian sites are participating, with 48 screened cases, 42 enrolled, with 19 still active in the study.

Autoimmune neuromuscular disorders

Autoimmune neuromuscular disorders affecting peripheral nerves, neuromuscular junction or muscle have a wide clinical spectrum with diverse pathogenetic mechanisms. Peripheral nervous system may be targeted in the context of complex immune reactions involving different cytokines, antigen-presenting cells, B cells and different types of T cells. Various immunomodulating and cytotoxic treatments block proliferation or activation of immune cells by different mechanisms attempting to control the response of the immune system and limit target organ injury. Most treatment protocols for autoimmune neuromuscular disorders are based on the use of corticosteroids, intravenous immunoglobulins and plasmapheresis, with cytotoxic agents mostly used as steroid-sparing medications. More recently, development of specific monoclonal antibodies targeting individual cell types allowed a different approach targeting specific immune pathways, but these new treatments are also associated with various adverse effects and their long-term efficacy is still unknown.

Dentistry and the myasthenia gravis patient: a review of the current state of the art

Myasthenia gravis (MG) is a chronic neuromuscular disease characterized by muscular weakness and fatigability. Dental management of patients diagnosed with MG presents a challenge to the oral health care provider. The purpose of this article was to review the etiology, pathogenesis, diagnosis, and clinical signs and symptoms associated with MG, highlighting the role of the oral health care provider in the process of diagnosis and management of the oral and dental complications that might be associated with the disease, while avoiding myasthenic crisis. A discussion of the recent approaches to treatment of the disease and current research on MG is presented.

Immunotherapies in neurologic disorders

Therapy for autoimmune demyelinating disorders has evolved rapidly over the past 10 years to include traditional immunosuppressants as well as novel biologicals. Antibody-mediated neuromuscular disorders are treated with therapies that acutely modulate pathogenic antibodies or chronically inhibit the humoral immune response. In other inflammatory autoimmune disorders of the peripheral and central nervous system, corticosteroids, often combined with conventional immunosuppression, and immunomodulatory treatments are used. Because autoimmune neurologic disorders are so diverse, evidence from randomized controlled trials is limited for most of the immunotherapies used in neurology. This review provides an overview of the immunotherapies currently used for neurologic disorders.

Progress in the treatment of myasthenia gravis

Substantial therapeutic progress has been made in myasthenia gravis (MG) even before the era of molecular medicine. Here we characterize modern treatment algorithms that are adapted to disease severity and introduce the principle of escalating treatment strategies for MG. In very mild cases and in some ocular forms of MG, treatment with acetylcholinesterase inhibitors may be sufficient, at least temporarily, but commonly some kind of immunologically active treatment is needed. In generalized MG, a wide array of immunosuppressive treatments has been established through observational studies, some prospective, but most of them have never been tested in a double-blind, prospective and randomized trial. Within the immunologically active drugs, glucocorticosteroids (GCS) and the immunosuppressive drug azathioprine (Aza) have been studied the longest. Aza is still the standard base-line treatment, in particular in cases where high doses of GCS would be needed to maintain remission. If Aza is not tolerated, several alternatives are available including cyclosporine A (Cic A), mycophenolate mofetil, cyclophosphamide, and methotrexate, all of them off-label in most western countries. Tacrolimus is under investigation. More severe cases may profit from drug combinations in which compounds with more rapidly acting drugs (GCS, Cic A) are combined with others showing a more delayed action (Aza). All such combination therapies need to be supervised by an experienced neuroimmunological center because of potentially serious adverse reactions. Serial measurements of anti-acetylcholine receptor antibodies, once these are elevated, is a useful adjunct for monitoring long-term treatment success and may help in weaning from higher to lower doses or to single drugs rather than combinations. For very severe and treatment-resistant cases, co-treatment with intravenous immunoglobulins or different modalities of plasmapheresis may be considered on the short term while the humanized monoclonal anti-CD 20 antibody (rituximab) is a candidate for the long term. In highly refractory cases also immuno-ablation via high-dose cyclophosphamide, followed by hematologic trophic factors such as G-CSF, has been tried successfully. Future developments may include other immunologically active monoclonal antibodies (e.g., anti-CD 52, Campath-1). Up to 10% of patients with MG are associated with a malignant thymoma, often referred to as paraneoplastic MG, as detected by CT scan or MRI, and these patients require thymomectomy and sometimes postsurgical chemotherapy and radiation treatment. In nonthymoma patients with generalised MG, including older children and adults up to the 5th decade, a complete transsternal thymectomy is recommended based on available open trials and expert opinion, preferentially during the first year of disease. Endoscopic surgery may also be effective. Before surgery, pretreatment with immunosuppressive medication or plasmapheresis is usually recommended to ameliorate MG and subsequently reduce perioperative morbidity and mortality which is now near zero in experienced centers. Myasthenic crisis is the life-threatening exacerbation of MG and is best treated by plasmapheresis, mostly combined with immunoadsorption techniques. Intravenous immunoglobulins are a reasonable alternative, but a shortage in supplies and high prices limit its use.

Treatment of relapsing-remitting multiple sclerosis with high-dose cyclophosphamide induction followed by glatiramer acetate maintenance

BACKGROUND

Previous studies have described stabilization of aggressive multiple sclerosis (MS) with one-time induction therapy with high-dose cyclophosphamide (HiCy). The long-term benefit of this stabilization followed by conventional therapy has not been explored.

OBJECTIVE

The objective of this study was to evaluate the safety and clinical outcomes following treatment of relapsing-remitting MS with HiCy induction therapy followed by glatiramer acetate maintenance.

METHODS

A retrospective review of a closely followed population of thirty two MS patients treated with HiCy (200mg/kg intravenous infusion over 4 days) followed by maintenance with glatiramer acetate was performed.

RESULTS

Annualized relapse rate was reduced from 1.37 in the 2 years prior to treatment to 0.27 over a mean post-treatment follow-up period of 14 months (range 0.5-33.8). The projected probability of relapse-free survival at 2 years was 0.64 (95% CI 0.37-0.82). The projected probability of Expanded Disability Status Scale (EDSS) progression-free survival at 2 years was 0.77 (95% CI 0.43-0.92). The mean number of gadolinium-enhanced lesions was reduced from 0.86 (SD 1.6) at baseline to 0 at 12 months and 0.08 (SD 0.28) at 15-24 months. A total of 55% of patients had no evidence of disease activity in follow-up. Infectious complications occurred in 47% with no long-term morbidity and no deaths.

CONCLUSIONS

Induction therapy with HiCy followed by long-term maintenance with glatiramer acetate is well tolerated in patients with MS, and appears to be efficacious in reducing the risk of relapse, disability progression, and new MRI lesions.

Cyclophosphamide in multiple sclerosis: scientific rationale, history and novel treatment paradigms

For patients with relapsing-remitting multiple sclerosis (RRMS), there are currently six approved medications that have been shown to alter the natural course of the disease. The approved medications include three beta interferon formulations, glatiramer acetate, natalizumab and mitoxantrone. Treating aggressive forms of RRMS and progressive disease forms of MS still presents a great challenge to neurologists. Intense immunosuppression has long been thought to be the only feasible therapeutic option. In patients with progressive forms of MS, lymphoid tissues have been detected in the central nervous system (CNS) that may play a critical role in perpetuating local inflammation. Agents that are currently approved for patients with MS have no or very limited bioavailability in the brain and spinal cord. In contrast, cyclophosphamide (CYC), an alkylating agent, penetrates the blood-brain barrier and CNS parenchyma well. However, while CYC has been used in clinical trials and off-label in clinical practice in patients with MS for over three decades, data on its efficacy in very heterogeneous groups of study patients have been conflicting. New myeloablative treatment paradigms with CYC may provide a therapeutic option in patients that do not respond to other agents. In this article we review the scientific rationale that led to the initial clinical trials with CYC. We will also outline the safety, tolerability and efficacy of CYC and provide neurologists with guidelines for its use in patients with MS and other inflammatory disorders of the CNS, including neuromyelitis optica (NMO). Finally, an outlook into relatively novel treatment approaches is provided.

Immunosuppressive therapies in myasthenia gravis

Immunosuppression is the mainstay of treatment for myasthenia gravis (MG). In this paper, we review the mechanisms of action and clinical application of corticosteroids and different classes of immunosuppressive drugs that are currently used in MG patients, and present the results of their use in more than 1000 patients with MG seen at our two centers. Immunosuppressive treatment was considered along with, or as an alternative to thymectomy in MG patients with disabling weakness, not adequately controlled with anticholinesterase drugs. Overall, 82% of our patients received immunosuppressants for at least 1 year, with frequencies varying according to disease severity, from 93-95% of those with thymoma or MuSK antibodies to 72% in ocular myasthenia. Prednisone was used in the great majority of patients, azathioprine was the first-choice immunosuppressant; mycophenolate mofetil and cyclosporine were used as second-choice agents. All clinical forms of MG benefited from immunosuppression: the rate of remission or minimal manifestations ranged from 85% in ocular myasthenia to 47% in thymoma-associated disease. Treatment was ultimately withdrawn in nearly 20% of anti-AChR positive early-onset patients, but in only 7% of thymoma cases. The risk of complications appears to depend on drug dosage, treatment duration, and patient characteristics, the highest rate of serious side effects (20%) having been found in late-onset MG and the lowest (4%) in early-onset disease. Although nonspecific, current immunosuppressive treatment is highly effective in most MG patients. Lack of randomized evidence, the need for prolonged administration, and unwanted effects are still relevant limitations to its use.

Quality of life and life circumstances in German myasthenia gravis patients

BACKGROUND

Myasthenia gravis (MG) is a chronic neuromuscular disease. Advances in medical therapy have continuously increased the life expectancy of MG patients, without definitively curing the disease. To analyze life circumstances and quality of life (QoL), a large German MG cohort was investigated.

METHODS AND SAMPLE

In cooperation with the German Myasthenia Association, 2,150 patients with confirmed MG were asked to respond to a mailed questionnaire. The standardized questions related to demographic data, impairments, therapeutic course, use of complementary therapies, illness-related costs, and quality of life (SF-36). In total, 1,518 patients participated, yielding a response rate of 70.6%. The average age was 56.7 years, and the proportion of females 58.6%.

RESULTS

Despite receiving recommended therapy, many patients still suffered from MG-related impairments. In particular, mobility and mental well-being were reduced; moreover, quality of life was markedly reduced. Stepwise linear regression analysis revealed illness stability, impairments, mental conditions, comorbid diseases, and employment to be determinants of QoL.

CONCLUSION

Results indicate that despite prolonged life expectancy among MG patients, health-related quality of life is low. This outcome resulted mainly from impaired mobility and depression. Physical and mental well-being might be improved by additional therapy options. Additionally, health care resources could be used more efficiently in these patients.

High-dose cyclophosphamide for autoimmunity and alloimmunity

High-dose cyclophosphamide (high-CY) is a potent immunosuppressive regimen that is increasingly used to mitigate both autoimmune and alloimmune conditions. Differential expression of aldehyde dehydrogenase between hematopoietic stem cells and lymphocytes accounts for the differential sensitivity of these cells to high-CY and explains why this regimen is immunosuppressive but not myeloablative. This article describes the clinical translation of high-CY for the treatment of autoimmune and alloimmune conditions.

High-dose cyclophosphamide for severe aplastic anemia: long-term follow-up

Severe aplastic anemia (SAA) is a life-threatening bone marrow failure disorder that can be treated with bone marrow transplantation, immunosuppressive therapy, and high-dose cyclophosphamide. Here, we report long-term follow-up on 67 SAA patients (44 treatment-naive and 23 refractory) treated with high-dose cyclophosphamide. At 10 years, the overall actuarial survival was 88%, the response rate was 71% with the majority being complete, and the actuarial event-free survival was 58% in 44 treatment-naive SAA patients. Patients with refractory SAA fared less well after high-dose cyclophosphamide therapy; at 10 years, overall actuarial survival, response, and actuarial event-free survival rates were 62%, 48%, and 27%, respectively. High-dose cyclophosphamide is highly effective therapy for severe aplastic anemia. Large randomized controlled trials will be necessary to establish how results of high-dose cyclophosphamide compare with either bone marrow transplantation or standard immunosuppressive regimens, such as antithymocyte globulin and cyclosporine.

Current and future immunotherapy in myasthenia gravis

Current therapy for myasthenia gravis is directed towards generalized modulation and suppression of the immune system. These approaches have been extensively studied and are effective in many patients with myasthenia, but at the cost of significant adverse effects due to the global effects on the immune system. Future directions in therapy are geared towards focused immunotherapies that aim to improve outcomes while lessening the burden of side effects. This paper reviews both the current accepted treatments for myasthenia gravis as well as promising targeted therapies in development.

Muscle-specific receptor tyrosine kinase antibody positive myasthenia gravis current status

Muscle-specific tyrosine-kinase-antibody-positive myasthenia gravis (MuSK-MG) has emerged as a distinct entity since 2001. This disease has been reported worldwide, but with varying rates among patients with generalized acetylcholine-receptor-antibody-negative MG. MuSK-MG was detected in approximately 37% of generalized acetylcholine receptor antibody-negative MG. MuSK-MG patients were predominantly female with more prominent facial and bulbar involvement and more frequent crises. Disease onset tended to be earlier. Patients tended to have a relatively poor edrophonium response but showed prominent decrement in the repetitive nerve stimulation test in the facial muscles. Patients were more likely to display poor tolerance of, or a lack of improvement with, anticholinesterase agents. Somewhat better response was observed with steroids and plasma exchange. Most were managed successfully with aggressive immunomodulatory therapies, although a higher proportion of MuSK-MG patients had a refractory course when compared with other forms of generalized MG. I present here an up-to-date overview on MuSK-MG based on our experience at the University of Alabama at Birmingham and the existing literature.

Autoimmune myasthenia gravis: emerging clinical and biological heterogeneity

Acquired myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junction in which patients experience fluctuating skeletal muscle weakness that often affects selected muscle groups preferentially. The target of the autoimmune attack in most cases is the skeletal muscle acetylcholine receptor (AChR), but in others, non-AChR components of the neuromuscular junction, such as the muscle-specific receptor tyrosine kinase, are targeted. The pathophysiological result is muscle endplate dysfunction and consequent fatigable muscle weakness. Clinical presentations vary substantially, both for anti-AChR positive and negative MG, and accurate diagnosis and selection of effective treatment depends on recognition of less typical as well as classic disease phenotypes. Accumulating evidence suggests that clinical MG subgroups might respond differently to treatment. In this Review, we provide current information about the epidemiology, immunopathogenesis, clinical presentations, diagnosis, and treatment of MG, including emerging therapeutic strategies.