Efficacy and safety of iscalimab, a novel anti-CD40 monoclonal antibody, in moderate-to-severe myasthenia gravis: A phase 2 randomized study

BACKGROUND

Increased morbidity in many patients with myasthenia gravis (MG) on long-term immunosuppression highlights the need for improved treatments. The aim of this study is to investigate the safety and efficacy of iscalimab (CFZ533), a fully human anti-CD40 monoclonal antibody, in patients with moderate-to-severe MG receiving standard-of-care (SoC) therapies.

METHODS

In this double-blind, placebo-controlled phase 2 study, symptomatic patients (n = 44) despite SoC were randomized 1:1 to receive intravenous iscalimab (10 mg/kg; n = 22) or placebo (n = 22) every 4 weeks for 6 doses in total. Patients were followed up for 6 months after the last dose. The total duration of the study was 52 weeks.

RESULTS

In total, 34 of 44 patients (77.3 %) completed the study. The primary endpoint, Quantitative MG score, did not change significantly between baseline and week 25 for iscalimab (median [90 % CI], -4.07 [-5.67, -2.47]) versus placebo (-2.93 [-4.53, -1.33]); however, non-thymectomized patients (n = 29) showed more favorable results (iscalimab, -4.35 [-6.07, -2.64] vs placebo, -2.26 [-4.16, -0.36]). A statistically significant difference between iscalimab and placebo groups was observed in MG Composite score (adjusted mean change: -4.19 [-6.67, -1.72]; p = 0.007) at week 13, and MG-Activities of Daily Living score (-1.93 [-3.24, -0.62]; p = 0.018) at week 21. Adverse events were comparable between the iscalimab (91 %) and placebo (96 %) groups.

CONCLUSION

Iscalimab showed favorable safety and improvements compared with placebo in non-thymectomized patients with moderate-to-severe MG. It did not show any protective effect in patients with moderate-to-severe MG.

Five-Year Extension Results of the Phase 1 START Trial of Onasemnogene Abeparvovec in Spinal Muscular Atrophy

Importance

This ongoing study assesses long-term safety and durability of response in infants with spinal muscular atrophy (SMA) type 1 after dosing with onasemnogene abeparvovec gene replacement therapy.

Objective

The primary objective of this ongoing study is to assess safety. The secondary objective is to determine whether developmental milestones achieved in the START phase 1 clinical trial were maintained and new milestones gained.

Design, Setting, and Participants

This study is an ongoing, observational, follow-up study for continuous safety monitoring for 15 years in patients from the START phase I study (conducted May 5, 2014, through December 15, 2017) at Nationwide Children's Hospital in Columbus, Ohio. Participants were symptomatic infants with SMA type 1 and 2 copies of SMN2 previously treated with an intravenous dose of onasemnogene abeparvovec (low dose, 6.7 × 1013 vg/kg; or therapeutic dose, 1.1 × 1014 vg/kg) in START. Thirteen of 15 original START patients are included in this analysis; 2 patients' families declined follow-up participation. Data were analyzed from September 21, 2017, to June 11, 2020.

Exposures

Median time since dosing of 5.2 (range, 4.6-6.2) years; 5.9 (range, 5.8-6.2) years in the low-dose cohort and 4.8 (range, 4.6-5.6) years in the therapeutic-dose cohort.

Main Outcomes and Measures

The primary outcome measure was the incidence of serious adverse events (SAEs).

Results

At data cutoff on June 11, 2020, 13 patients treated in START were enrolled in this study (median age, 38.9 [range, 25.4-48.0] months; 7 females; low-dose cohort, n = 3; and therapeutic-dose cohort, n = 10). Serious adverse events occurred in 8 patients (62%), none of which resulted in study discontinuation or death. The most frequently reported SAEs were acute respiratory failure (n = 4 [31%]), pneumonia (n = 4 [31%]), dehydration (n = 3 [23%]), respiratory distress (n = 2 [15%]), and bronchiolitis (n = 2 [15%]). All 10 patients in the therapeutic-dose cohort remained alive and without the need for permanent ventilation. Prior to baseline, 4 patients (40%) in the therapeutic-dose cohort required noninvasive ventilatory support, and 6 patients (60%) did not require regular ventilatory support, which did not change in long-term follow-up. All 10 patients treated with the therapeutic dose maintained previously acquired motor milestones. Two patients attained the new milestone of "standing with assistance" without the use of nusinersen.

Conclusions and Relevance

The findings of this ongoing clinical follow-up of patients with SMA type 1 treated with onasemnogene abeparvovec supports the long-term favorable safety profile up to 6 years of age and provides evidence for sustained clinical durability of the therapeutic dose.

Trial Registration

ClinicalTrials.gov Identifier: NCT03421977.

Severe Exacerbation of Myasthenia Gravis Associated with Checkpoint Inhibitor Immunotherapy

Monoclonal antibodies that target either PD-1 or PD-L1 have recently been approved for treatment of advanced non-small cell lung cancer. These antibodies are immune checkpoint inhibitors which have been shown to exacerbate Myasthenia Gravis (MG) and other autoimmune diseases. While effective in preventing tumor cells from evading immune attack, immune checkpoint inhibitors such as nivolumab, an antibody directed against the programmed cell death protein-1 (PD-1) receptor located on T-cells, may also cause immune dysregulation and could cause or potentiate pre-existing autoimmune conditions. We present a patient with latent ocular MG treated with nivolumab for her stage IV non-small cell lung cancer who developed generalized MG and severe myasthenic crisis. Providers must be aware of the risks inherent to these novel therapies since they can have life-threatening effects.

Safety, tolerability, and preliminary efficacy of an IGF-1 mimetic in patients with spinal and bulbar muscular atrophy: a randomised, placebo-controlled trial

BACKGROUND

Spinal and bulbar muscular atrophy is an X-linked neuromuscular disease caused by CAG repeat expansion in the androgen receptor gene. Patients with this disease have low concentrations of insulin-like growth factor-1 (IGF-1), and studies of overexpression and administration of IGF-1 showed benefit in a transgenic model; thus the IGF-1 pathway presents as a potential treatment target. We assessed safety, tolerability, and preliminary efficacy of BVS857, an IGF-1 mimetic, in patients with spinal and bulbar muscular atrophy.

METHODS

In this randomised, double-blind, placebo-controlled trial, we recruited patients from neuromuscular centres in Denmark (Copenhagen), Germany (Ulm), Italy (Padova), and three sites within the USA (Bethesda, MD; Irvine, CA; and Columbus, OH). Eligible patients were 18 years or older with a confirmed genetic diagnosis of spinal and bulbar muscular atrophy, were ambulatory, had symptomatic weakness, and had serum IGF-1 concentrations of 170 ng/mL or lower. Patients were randomly assigned (2:1) to study drug or placebo by a number scheme. Patients, investigators, and study personnel were masked to treatment assignment. After a safety and tolerability assessment with eight patients, BVS857 was administered once a week (0·06 mg/kg intravenously) for 12 weeks. Primary outcome measures were safety, tolerability, and the effects of BVS857 on thigh muscle volume (TMV) measured by MRI. The ratio of TMV at day 85 to baseline was analysed with ANCOVA per protocol. Secondary outcomes of muscle strength and function were measured with the Adult Myopathy Assessment Tool, lean body mass through dual energy x-ray absorptiometry, and BVS857 pharmacokinetics. This trial was registered with ClinicalTrials.gov, NCT02024932.

FINDINGS

31 patients were assessed for eligibility, 27 of whom were randomly assigned to either BVS857 treatment (n=18) or placebo (n=9), and 24 were included in the preliminary efficacy analysis (BVS857 group, n=15; placebo group, n=9). BVS857 was generally safe with no serious adverse events. No significant differences were found in adverse events between the BVS857 and placebo groups. Immunogenicity was detected in 13 (72%) of 18 patients in the BVS857 group, including crossreacting antibodies with neutralising capacity to endogenous IGF-1 in five patients. TMV decreased from baseline to day 85 in the placebo group (-3·4% [-110 cm³]) but not in the BVS857 group (0% [2 cm³]). A significant difference in change in TMV was observed in the BVS857 group versus the placebo group (geometric-mean ratio 1·04 [90% CI 1·01-1·07]; p=0·02). There were no differences between groups in measures of muscle strength and function.

INTERPRETATION

TMV remained stable in patients with spinal and bulbar muscular atrophy after being given BVS857 for 12 weeks. The intervention was associated with high incidence of immunogenicity and did not improve muscle strength or function. Additional studies might be needed to assess the efficacy of activating the IGF-1 pathway in this disease.

FUNDING

Novartis Pharmaceuticals and the US National Institutes of Health.

Current Treatment, Emerging Translational Therapies, and New Therapeutic Targets for Autoimmune Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune disease associated with the production of autoantibodies against 1) the skeletal muscle acetylcholine receptor; 2) muscle-specific kinase, a receptor tyrosine kinase critical for the maintenance of neuromuscular synapses; 3) low-density lipoprotein receptor-related protein 4, an important molecular binding partner for muscle-specific kinase; and 4) other muscle endplate proteins. In addition to the profile of autoantibodies, MG may be classified according the location of the affected muscles (ocular vs generalized), the age of symptom onset, and the nature of thymic pathology. Immunopathologic events leading to the production of autoantibodies differ in the various disease subtypes. Advances in our knowledge of the immunopathogenesis of the subtypes of MG will allow for directed utilization of the ever-growing repertoire of therapeutic agents that target distinct nodes in the immune pathway relevant to the initiation and maintenance of autoimmune disease. In this review, we examine the pathogenesis of MG subtypes, current treatment options, and emerging new treatments and therapeutic targets.

Prospect for pharmacological therapies to treat skeletal muscle dysfunction

Skeletal muscle weakness is a leading cause of mobility disability in the elderly (sarcopenia), as a complication of acute or chronic illness (cachexia), and due to inherited or acquired muscle diseases (muscular dystrophies, myositides, etc.). As of now, there are no approved drugs that can reliably increase muscle strength and function. However, with our understanding of the regulation of myocyte signaling and homeostasis evolving rapidly, experimental treatments are now entering the clinic. We review the current status of clinical research in pharmacological therapies for muscle disorders.

Use of immunoassays in neurological diagnosis and research

OBJECTIVES

To review the use of immunoassays in the diagnosis and research of disorders affecting the nervous system.

METHODS

Systematic review of the English literature.

RESULTS

Immunoassays have demonstrated utility for: (1) the detection of antigen (molecules, genes, gene products, peptides, hormones and drug metabolites) and (2) the detection of an immune response (antigen-antibody complexes and specific and non-specific populations of antibodies) in serum, cerebrospinal fluid, and central nervous system tissue.

DISCUSSION

The specificity of the antibody-antigen interaction makes immunoassays an ideal diagnostic and research tool for the investigation of neurological disease. A number of immunoassays are available for this purpose, and the choice of a particular methodology generally depends upon whether one is detecting antigen, antibody or antigen-antibody complexes, and the nature of the biologic sample that is being tested. Ease of testing, sensitivity, specificity and cost are other important considerations.

Functional defect in regulatory T cells in myasthenia gravis

Forkhead box P3 (FOXP3) is a transcription factor necessary for the function of regulatory T cells (T(reg) cells). T(reg) cells maintain immune homeostasis and self-tolerance and play an important role in the prevention of autoimmune disease. Here, we discuss the role of T(reg) cells in the pathogenesis of myasthenia gravis (MG) and review evidence indicating that a significant defect in T(reg) cell in vitro suppressive function exists in MG patients, without an alteration in circulating frequency. This functional defect is associated with a reduced expression of key functional molecules, such as FOXP3 on isolated T(reg) cells, and appears to be more pronounced in immunosuppression-naive MG patients. In vitro administration of granulocyte macrophage-colony-stimulating factor (GM-CSF) enhanced the suppressive function of T(reg) cells and upregulated FOXP3 expression. These findings indicate a clinically relevant T(reg) cell-intrinsic defect in immune regulation in MG that may reveal a novel therapeutic target.

Muscle autoantibodies in myasthenia gravis: beyond diagnosis?

Myasthenia gravis is an autoimmune disorder of the neuromuscular junction. A number of molecules, including ion channels and other proteins at the neuromuscular junction, may be targeted by autoantibodies leading to abnormal neuromuscular transmission. In approximately 85% of patients, autoantibodies, directed against the postsynaptic nicotinic acetylcholine receptor can be detected in the serum and confirm the diagnosis, but in general, do not precisely predict the degree of weakness or response to therapy. Antibodies to the muscle-specific tyrosine kinase are detected in approximately 50% of generalized myasthenia gravis patients who are seronegative for anti-acetylcholine receptor antibodies, and levels of anti-muscle-specific tyrosine kinase antibodies do appear to correlate with disease severity and treatment response. Antibodies to other muscle antigens may be found in the subsets of myasthenia gravis patients, potentially providing clinically useful diagnostic information, but their utility as relevant biomarkers (measures of disease state or response to treatment) is currently unclear.

Granulocyte macrophage colony-stimulating factor treatment of a patient in myasthenic crisis: effects on regulatory T cells

INTRODUCTION

In this study we describe a patient with a prolonged myasthenic crisis refractory to conventional immunomodulatory therapy who was treated with GM-CSF (granulocyte macrophage colony-stimulating factor, sargramostim).

METHODS

T-regulatory cell (Treg) suppressive function and Foxp3 expression were evaluated before and after treatment with GM-CSF.

RESULTS

Treatment with GM-CSF was associated with clinical improvement, expansion in the circulating numbers of Foxp3(+) cells, increase in Foxp3 expression levels in Tregs, early improvement in Treg suppressive capacity for AChR-α-induced T-cell proliferation, and subsequent enhancement in Treg suppression of polyclonal T-cell proliferation.

CONCLUSION

Although definitive conclusions cannot be drawn from a single case, the correlation with similar findings in GM-CSF-treated animals with experimental autoimmune myasthenia gravis suggests further exploration of the effects of GM-CSF in myasthenia gravis should be studied in a clinical trial setting.

GM-CSF-induced regulatory T cells selectively inhibit anti-acetylcholine receptor-specific immune responses in experimental myasthenia gravis

We and others have demonstrated the ability of granulocyte-macrophage colony-stimulating factor (GM-CSF) to suppress autoimmunity by increasing the number of CD4(+)CD25(+) regulatory T cells (Tregs). In the current study, we have explored the critical role of induced antigen specific Tregs in the therapeutic effects of GM-CSF in murine experimental autoimmune myasthenia gravis (EAMG). Specifically, we show that Tregs from GM-CSF treated EAMG mice (GM-CSF/AChR-induced-Tregs) adoptively transferred into animals with EAMG suppressed clinical disease more potently than equal numbers of Tregs from either GM-CSF untreated EAMG mice or healthy mice treated with GM-CSF. In addition, GM-CSF/AChR-induced-Tregs selectively suppressed antigen specific T cell proliferation induced by AChR relative to that induced by an irrelevant self antigen, (thyroglobulin) and failed to significantly alter T cell proliferation in response to an exogenous antigen (ovalbumin). These results are consistent with the hypothesized mechanism of action of GM-CSF involving the mobilization of tolerogenic dendritic cell precursors which, upon antigen (AChR) capture, suppress the anti-AChR immune response through the induction/expansion of AChR-specific Tregs.

Novel LMNA mutations in patients with Emery-Dreifuss muscular dystrophy and functional characterization of four LMNA mutations

Mutations in LMNA cause a variety of diseases affecting striated muscle including autosomal Emery-Dreifuss muscular dystrophy (EDMD), LMNA-associated congenital muscular dystrophy (L-CMD), and limb-girdle muscular dystrophy type 1B (LGMD1B). Here, we describe novel and recurrent LMNA mutations identified in 50 patients from the United States and Canada, which is the first report of the distribution of LMNA mutations from a large cohort outside Europe. This augments the number of LMNA mutations known to cause EDMD by 16.5%, equating to an increase of 5.9% in the total known LMNA mutations. Eight patients presented with either p.R249W/Q or p.E358K mutations and an early onset EDMD phenotype: two mutations recently associated with L-CMD. Importantly, 15 mutations are novel and include eight missense mutations (p.R189P, p.F206L, p.S268P, p.S295P, p.E361K, p.G449D, p.L454P, and p.W467R), three splice site mutations (c.IVS4 + 1G>A, c.IVS6 - 2A>G, and c.IVS8 + 1G>A), one duplication/in frame insertion (p.R190dup), one deletion (p.Q355del), and two silent mutations (p.R119R and p.K270K). Analysis of 4 of our lamin A mutations showed that some caused nuclear deformations and lamin B redistribution in a mutation specific manner. Together, this study significantly augments the number of EDMD patients on the database and describes 15 novel mutations that underlie EDMD, which will contribute to establishing genotype-phenotype correlations.

In vivo adsorption of autoantibodies in myasthenia gravis using Nanodisc-incorporated acetylcholine receptor

Autoantibodies directed against the skeletal muscle acetylcholine receptor (AChR) play a critical role in the pathogenesis of the autoimmune disease, myasthenia gravis (MG). The pathogenic importance of anti-AChR antibodies is substantiated clinically by the often dramatic clinical improvement that follows removal of circulating antibodies utilizing extracorporeal plasma exchange (PE). Unfortunately, the effects of PE are non-specific as immunoglobulins (IgG) and other plasma proteins are removed in addition to anti-AChR IgG. In this study, we have successfully incorporated the AChR protein purified from Torpedo californicus into a Nanodisc (ND) membrane scaffold protein/phospholipid structure. We go on to demonstrate the effectiveness of this ND-AChR complex, administered intravenously, in the in vivo down-modulation of anti-AChR antibodies and subsequent amelioration of clinical disease in the experimental murine model of MG. These results provide proof-of-principle for the in vivo antigen-specific reduction of pathogenic anti-AChR antibodies utilizing ND-AChR particles. Further development of this strategy may provide an effective, antigen-specific, and readily accessible acute therapy for exacerbating MG or myasthenic crisis.

Acetylcholine receptor-alpha subunit expression in myasthenia gravis: a role for the autoantigen in pathogenesis?

Previous studies have shown increased expression of acetylcholine receptor-alpha (AChR-alpha) subunit transcripts in myasthenia gravis (MG) and experimental MG (EAMG), but none examined the functional properties of this overexpression. In this study we examined the mRNA and protein expression of AChR-alpha as well as the pattern of alpha-bungarotoxin labeling in muscle tissue from EAMG mice with varying disease severity. AChR-alpha expression was increased considerably in endplates from mice with severe EAMG, but it was distinct and greatly in excess of alpha-bungarotoxin labeling. This "aberrant expression" occurred in mice with morphologic endplate damage, and the pattern of complement and immunoglobulin deposition in muscle from these mice appeared to mirror the pattern of AChR-alpha expression. The loss of functional AChR in severe MG increases transcription of AChR-alpha mRNA, but the expressed protein is "functionally inert," failing to compensate for loss of AChR. This enhanced expression of AChR may play a role in driving the ongoing autoimmune response. Muscle Nerve 40: 279-286, 2009.

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.

Acetylcholine Receptor-alpha Subunit Over-Expression in Experimental Myasthenia Gravis: A Possible Role for the Autoantigen in Pathogenesis (137.1)

Previous studies have shown an increased expression of AChR alpha (AChR-α) subunit transcripts in experimental autoimmune myasthenia gravis (EAMG). We examined the mRNA and protein expression of AChR-α, as well as the pattern of α-bungarotoxin labeling in muscle tissue from EAMG mice. AChR-α expression was profoundly increased in endplates from mice with severe EAMG, but this expression was distinct and greatly in excess of α-bungarotoxin labeling. These results suggest that loss of functional AChR increases transcription of AChR-α mRNA, but the expressed protein is "functionally inert," failing to compensate for loss of AChR, and very likely enhancing immunogenicity.

Regulation of apoptosis and caspase-8 expression in neuroblastoma cells by isoforms of the IG20 gene

The IG20 gene undergoes alternative splicing resulting in the differential expression of six putative splice variants. Four of these (IG20pa, MADD, IG20-SV2, and DENN-SV) are expressed in virtually all human tissues. However, investigations examining alternative splicing of the IG20 gene to date have been largely limited to nonneural malignant and nonmalignant cells. In this study, we investigated the expression of alternative splice isoforms of the IG20 gene in human neuroblastoma cells. We found that six IG20 splice variants (IG20-SVs) were expressed in two human neuroblastoma cell lines (SK-N-SH and SH-SY5Y), highlighted by the expression of two unique splice isoforms (i.e., KIAA0358 and IG20-SV4). Similarly, we found enriched expression of these two IG20-SVs in human neural tissues derived from cerebral cortex, hippocampus, and, to a lesser extent, spinal cord. Using gain-of-function studies and siRNA technology, we determined that these "neural-enriched isoforms" exerted significant and contrasting effects on vulnerability to apoptosis in neuroblastoma cells. Specifically, expression of KIAA0358 exerted a potent antiapoptotic effect in both the SK-N-SH and SH-SY5Y neuroblastoma cell lines, whereas expression of IG20-SV4 had proapoptotic effects directly related to the activation of caspase-8 in these cells, which have minimal or absent constitutive caspase-8 expression. These data indicate that the pattern of expression of these neural-enriched IG20-SVs regulates the expression and activation of caspase-8 in certain neuroblastoma cells, and that manipulation of IG20-SV expression pattern may represent a potent therapeutic strategy in the therapy of neuroblastoma and perhaps other cancers.

Strategies for treating autoimmunity: novel insights from experimental myasthenia gravis

Current treatments for myasthenia gravis (MG) rely upon the administration of immunosuppressive agents which result in global, nonspecific attenuation of the immune response. An alternative approach would be to attempt to design therapies that specifically dampen autoreactivity without affecting general immunity. Recently, dendritic cells (DCs) have been shown to possess potent capabilities to tolerize T cells in an antigen-specific manner. We have observed that the selective activation of particular subsets of DCs utilizing granulocyte-macrophage colony-stimulating factor (GM-CSF) had profound effects on the induction of experimental autoimmune myasthenia gravis (EAMG). Specifically, treatment with GM-CSF effectively suppressed the induction of EAMG and down-modulated anti-AChR T cell and pathogenic antibody responses. These effects were associated with the activation of tolerogenic DCs, the enhanced production of suppressive cytokines, such as IL-10, and the mobilization of CD4(+)CD25(+) and FoxP3(+) regulatory T cells (Tregs). We have further shown that GM-CSF effectively ameliorates clinical disease severity in mice with active, ongoing EAMG. Based on these observations, we hypothesize that the selective activation of particular DC subsets in vivo using pharmacologic agents, like GM-CSF, can suppress ongoing anti-AChR immune responses by mobilizing antigen-specific Tregs capable of suppressing autoimmune MG.

Regulatory T cells induced by GM-CSF suppress ongoing experimental myasthenia gravis

We had previously observed that treatment utilizing granulocyte-macrophage colony-stimulating factor (GM-CSF) had profound effects on the induction of experimental autoimmune myasthenia gravis (EAMG), a well-characterized antibody-mediated autoimmune disease. In this study, we show that EAMG induced by repeated immunizations with acetylcholine receptor (AChR) protein in C57BL6 mice is effectively suppressed by GM-CSF treatment administered at a stage of chronic, well-established disease. In addition, this amelioration of clinical disease is accompanied by down-modulation of both autoreactive T cell, and pathogenic autoantibody responses, a mobilization of DCs with a tolerogenic phenotype, and an expansion of regulatory T cells (Tregs) that potently suppress AChR-stimulated T cell proliferation in vitro. These observations suggest that the mobilization of antigen-specific Tregs in vivo using pharmacologic agents, like GM-CSF, can modulate ongoing anti-AChR immune responses capable of suppressing antibody-mediated autoimmunity.

Therapeutic potential and the mechanism of action of Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) in established Experimental Autoimmune Myasthenia Gravis (128.13)

Dendritic cells (DCs) are potent antigen presenting cells responsible for priming naïve T cells in an immune response. Distinct subpopulations of DCs play a central role in immune regulation by preferentially inducing immunity or tolerance. Recently, we observed that the selective activation of particular subsets of DCs utilizing fms-like tyrosine kinase receptor 3 ligand (Flt3-L) and granulocyte-macrophage colony-stimulating factor (GM-CSF) had profound effects on the induction of Experimental Autoimmune Myasthenia Gravis (EAMG). Treatment with GM-CSF effectively suppressed the induction of EAMG, and down-modulated anti-AChR T cell and antibody responses. These effects were associated with the activation of CD8α- DCs, the enhanced production of suppressive cytokines such as IL-4 and IL-10, and the mobilization of CD4+CD25+ and Foxp3+ regulatory T cells (Tregs). Based on these observations, we hypothesized that the selective activation of DC subsets using GM-CSF can skew ongoing anti-AChR immune responses in favor of a Th2 polarization and mobilize antigen-specific CD4+CD25+ and Foxp3+ Tregs capable of suppressing established EAMG. In the present study, we evaluated the therapeutic potential of GM-CSF by examining its effectiveness in the treatment of established disease, and its ability to suppress ongoing autoimmune responses in active EAMG. We are continuing to understand the mechanisms of Treg induction and modes of action in the GM-CSF induced suppression of ongoing EAMG, with regard to antigen specificity and duration of induced tolerance.

Suppression of Experimental Autoimmune Myasthenia Gravis by Granulocyte-Macrophage Colony-Stimulating Factor Is Associated with an Expansion of FoxP3+Regulatory T Cells

Dendritic cells (DCs) have the potential to activate or tolerize T cells in an Ag-specific manner. Although the precise mechanism that determines whether DCs exhibit tolerogenic or immunogenic functions has not been precisely elucidated, growing evidence suggests that DC function is largely dependent on differentiation status, which can be manipulated using various growth factors. In this study, we investigated the effects of mobilization of specific DC subsets-using GM-CSF and fms-like tyrosine kinase receptor 3-ligand (Flt3-L)-on the susceptibility to induction of experimental autoimmune myasthenia gravis (EAMG). We administered GM-CSF or Flt3-L to C57BL/6 mice before immunization with acetylcholine receptor (AChR) and observed the effect on the frequency and severity of EAMG development. Compared with AChR-immunized controls, mice treated with Flt3-L before immunization developed EAMG at an accelerated pace initially, but disease frequency and severity was comparable at the end of the observation period. In contrast, GM-CSF administered before immunization exerted a sustained suppressive effect against the induction of EAMG. This suppression was associated with lowered serum autoantibody levels, reduced T cell proliferative responses to AChR, and an expansion in the population of FoxP3+ regulatory T cells. These results highlight the potential of manipulating DCs to expand regulatory T cells for the control of autoimmune diseases such as MG.

Mycophenolate mofetil in dermatomyositis: is it safe?

The authors report 10 patients with idiopathic dermatomyositis treated with mycophenolate mofetil in combination with corticosteroids. Successful steroid taper without disease relapse was achieved in six patients; however, in three patients, treatment was associated with opportunistic infections, leading to death in one patient. The disproportionately high rate of opportunistic infections in this group is considered.

Predictive value of serum anti-C1q antibody levels in experimental autoimmune myasthenia gravis

Components of the complement cascade and circulating immune complexes play important roles in both experimental autoimmune myasthenia gravis and myasthenia gravis in humans. Thus far, no serological factor has been identified to predict the clinical severity of either myasthenia gravis. Upon immunization with acetylcholine receptor, levels of complement factors C1q, C3 and CIC increase with time in sera from C57BL/6 (B6) mice. Both these and plasma samples from myasthenia gravis patients also contain anti-C1q antibodies. The serum levels of anti-C1q antibodies but not C1q, C3 and CIC are significantly correlated with the clinical severity in the experimental myasthenia mice. However, this correlation is not observed in myasthenia gravis patients.

Late appearance of dropped head syndrome after radiotherapy for Hodgkin's disease

We present three cases of dropped head syndrome that occurred as a complication of mantle field (i.e., lymph nodes of the neck, axillae, and mediastinum) or whole-body radiation therapy for Hodgkin's disease. These cases are characterized by a late onset (2-27 years after radiation treatment), fibrosis, and contraction of the anterior cervical muscles, and atrophy of the posterior neck and shoulder girdle. This report adds to the increasing literature about the late neurological complications of radiation therapy and describes a previously unrecognized cause of dropped head syndrome.

Advances in the diagnosis of neuromuscular junction disorders

Disorders of the neuromuscular junction have a wide range of clinical presentations, which frequently poses a diagnostic challenge to evaluating clinicians. This article describes the tests used in the diagnosis of diseases of the neuromuscular junction, reviews the evidence supporting the use of each test, and proposes guidelines for their efficient utilization. A focused review of the literature was employed. Reports from four main categories of diagnostic tests (pharmacologic, electrodiagnostic, immunologic, and miscellaneous tests) were reviewed, and the sensitivity and specificity of each test in the diagnosis of specific neuromuscular junction diseases were examined. The clinical presentation determines which diagnostic tests should be utilized in individual cases of suspected neuromuscular junction disease. However, knowledge of the sensitivity and specificity of each test can help to focus the diagnostic evaluation and maximize the diagnostic yield of each test.

Myasthenia gravis patients with low plasma IL-6 and IFN-γ benefit from etanercept treatment

Steroid-dependent myasthenia gravis patients improved following treatment with etanercept (recombinant human TNF receptor:Fc) in a prospective pilot trial. While the plasma anti-acetylcholine receptor antibody levels remained unaffected, etanercept treatment increased plasma levels of C3, circulating immune complexes, IL-10 and IFN-gamma. There was a direct correlation between plasma IL-6, TNF-alpha and IFN-gamma levels and the post-treatment clinical scores of patients. Moreover, patients with lower pre-treatment plasma IL-6 and IFN-gamma levels attained better clinical improvement following etanercept treatment.

Etanercept treatment in corticosteroid-dependent myasthenia gravis

The authors report a prospective pilot trial of etanercept in corticosteroid-dependent autoimmune myasthenia gravis. Eleven patients were enrolled, with eight completing the 6-month trial. Two patients were withdrawn owing to disease worsening, and one patient was withdrawn because of an erythematous skin rash. Six of the eight patients who completed the trial improved, based on quantitative measures of muscle strength and lowering of corticosteroid requirement.

Myasthenia gravis: diagnosis

The clinical history and neurological examination provide the most important data on which the diagnosis of autoimmune myasthenia gravis (MG) is based. MG produces symptomatic weakness that predominates in certain muscle groups and typically fluctuates in response to effort and rest. The diagnosis of MG therefore depends on the recognition of this distinctive pattern of fatigable weakness. Laboratory confirmation of the clinical diagnosis may be obtained using pharmacological, electrophysiological, and serological (immunological) tests. This article reviews the tests used to confirm the diagnosis of MG.

Mycophenolate mofetil for myasthenia gravis: an analysis of efficacy, safety, and tolerability

The authors report a retrospective analysis of the use of mycophenolate mofetil (MyM) in 85 patients with autoimmune myasthenia gravis. The Myasthenia Gravis Foundation of America (MGFA) postintervention status (PIS) was used to characterize the treatment response in each patient. Sixty-two patients (73%) achieved a PIS status indicating improvement. Quantitative strength testing performed on the majority of patients before and after treatment also improved. Side effects to MyM were observed in 27% of patients but required discontinuation in only 6%.

Single Fiber EMG as an Outcome Measure in Myasthenia Gravis: Results from a Double-Blind, Placebo-Controlled Trial

In a placebo-controlled, therapeutic, pilot trial of mycophenolate mofetil (MM) in autoimmune myasthenia gravis (MG), the authors compared pretreatment and posttreatment single fiber electromyography (SFEMG) jitter measurements performed on the same muscle in a total of 11 patients. The mean jitter value decreased (improved) by an average of 15.4 micros in patients receiving MM (n = 6), compared to an increase (worsening) in mean jitter of 4.0 micros in patients receiving placebo (n = 5). This difference was statistically significant (P = 0.030). In most patients, the change in SFEMG measurements correlated with the change in clinical state as measured by quantitative testing of muscle function. The authors conclude that immunomodulation by MM improves neuromuscular junction function in MG and that SFEMG may be a useful marker of early response in future therapeutic trials in autoimmune MG.

Mycophenolate Mofetil for Myasthenia Gravis A Double-Blind, Placebo-Controlled Pilot Study

Mycophenolate mofetil (MM) is an immunosuppressive agent developed and originally used to prevent acute rejection of solid-organ transplantation. There have been preliminary reports of its successful use in the treatment of autoimmune myasthenia gravis (MG). We conducted a double-blind, placebo-controlled pilot trial of MM in the treatment of suboptimally controlled, stable MG. Results of this pilot study are promising and suggestive of greater improvement in the patients who received MM compared to placebo.

Fatigue and abnormal neuromuscular transmission in Kennedy's disease

We describe a patient with Kennedy's disease (X-linked bulbospinal neuronopathy) who experienced leg muscle fatigue with long-distance running. The patient also reported muscle twitching involving the face and extremities and long-standing muscle cramps. Aside from mild facial and tongue weakness (and fasciculations), his examination was normal, including completely preserved muscle strength in the extremities. Electrodiagnostic evaluation revealed evidence for a chronic motor axonopathy/neuronopathy and abnormal sensory nerve action potentials. In addition, repetitive nerve stimulation studies were normal, but neuromuscular jitter tested in the same muscle was markedly abnormal. The normal clinical strength and repetitive nerve stimulation studies in a muscle showing markedly increased neuromuscular jitter suggested a mechanism for this patient's symptoms of muscle fatigue, related to failure of neuromuscular transmission at a critical number of endplates during extremes of physical activity.

Monomelic amyotrophy with late progression

Monomelic amyotrophy is a sporadic juvenile-onset disease that presents with gradual onset of weakness and atrophy in the hand muscles unilaterally. Generally, this disease is considered a 'benign' and non-progressive motor neuron disease, which stabilizes within five years of onset. We discuss a case that illustrates that monomelic amyotrophy may rarely exhibit late clinical progression to the lower extremities after a prolonged period of disease stability.

HMG-CoA Reductase Inhibitor Myopathy: Clinical, Electrophysiological, and Pathologic Data in Five Patients

OBJECTIVES

To define the clinical, electrophysiological, and pathologic features of the myopathy associated with the use of HMG CoA reductase inhibitors.

METHODS

Five patients with myopathy associated with HMG CoA reductase inhibitors were evaluated. Complete histories, physical examinations, manual muscle testing, serum creatine kinase, urine myoglobin measurements, electrodiagnostic studies, and muscle biopsy were performed.

RESULTS

Consistent features in our patients included a subacute onset of myalgias and weakness, electromyography demonstrating electrical myotonia, elevated creatine kinase levels, and in some patients myoglobinuria despite a relative lack of muscle necrosis on muscle biopsy and preserved myofibrillatory architecture by electron microscopy. All patients experienced resolution of symptoms within 3 weeks of drug discontinuation.

CONCLUSIONS

We postulate that the constellation of clinical, electrophysiological, and pathologic findings among our patients with HMG CoA reductase inhibitor myopathy may be explained by the early toxic effects of HMG CoA reductase inhibitors on muscle membrane organelles and sarcolemmal function. Patients on concurrent therapy with cyclosporine, gemfibrozil, and antifungal agents of the azole groups are at an increased risk of developing this toxic myopathy.