Between 1940 and 2000 a total of 1976 patients with myasthenia gravis (MG) were studied. Diagnosis was made by improvement in weakness after anticholinesterase medication. The historical developments ...in diagnosis and treatment of MG are reviewed. We analyzed the clinical course of MG as influenced by age, gender, thymectomy, thymomectomy, and the presence of antibodies to acetylcholine receptors (AChR). The clinical course of MG was significantly influenced by age and gender, and these need special attention in managing patients. The most severe level of weakness and high mortality occurred during the first 1 to 2 years of the disease, after which many patients experienced improvement. For treating MG patients the usefulness of thymectomy remains to be proven, and novel drugs need to be developed to increase the number as well as normal functioning of the AChRs and other components of the neuromuscular system. Muscle Nerve, 2007
Abstract The complement system is profoundly involved in the pathogenesis of acetylcholine receptor (AChR) antibody (Ab) related myasthenia gravis (MG) and its animal model experimental autoimmune ...myasthenia gravis (EAMG). The most characteristic finding of muscle pathology in both MG and EAMG is the abundance of IgG and complement deposits at the nerve–muscle junction (NMJ), suggesting that AChR-Ab induces muscle weakness by complement pathway activation and consequent membrane attack complex (MAC) formation. This assumption has been supported with EAMG resistance of complement factor C3 knockout (KO), C4 KO and C5 deficient mice and amelioration of EAMG symptoms following treatment with complement inhibitors such as cobra venom factor, soluble complement receptor 1, anti-C1q, anti-C5 and anti-C6 Abs. Moreover, the complement inhibitor decay accelerating factor (DAF) KO mice exhibit increased susceptibility to EAMG. These findings have brought forward improvisation of novel therapy methods based on inhibition of classical and common complement pathways in MG treatment.
OBJECTIVE:To report the clinical features of myasthenia gravis (MG) induced by treatment with immune checkpoint inhibitors using 2-year safety databases based on postmarketing surveys in Japan.
...METHODS:We studied 10,277 patients with cancer who had received monotherapy with either nivolumab or ipilimumab between September 2014 and August 2016. As the control group, 105 patients with idiopathic MG were used.
RESULTS:There were 12 MG cases (0.12%) among 9,869 patients with cancer who had been treated with nivolumab, but none among 408 patients treated with ipilimumab. These 12 patients included 6 men and 6 women with a mean age of 73.5 ± 6.3 years. MG onset occurred in the early phase after nivolumab treatment and rapidly deteriorated. Nivolumab-related MG (nivoMG) included 4 patients with mild involvement and 8 patients with severe involvement. Bulbar symptoms and myasthenic crisis were observed more frequently in nivoMG than idiopathic MG. Ten patients were positive for anti–acetylcholine receptor antibodies. Serum creatine kinase levels were markedly elevated to an average level of 4,799 IU/L. Among the 12 patients with nivoMG, 4 had myositis and 3 had myocarditis, with 1 of these patients having both. Immunosuppressive therapy was effective. Postintervention status showed that pharmacologic remission or minimal manifestations were obtained in 4 patients; however, 2 patients died. Immune-related adverse events triggered by nivolumab impaired the patientsʼ daily living activity.
CONCLUSIONS:The prompt and correct recognition of MG following treatment with immune checkpoint inhibitors in patients with cancer is important.
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.
Myasthenia Gravis Gilhus, Nils E
The New England journal of medicine,
12/2016, Letnik:
375, Številka:
26
Journal Article
Recenzirano
Myasthenia gravis is an autoimmune disease associated with several autoantibodies that attack the neuromuscular junction. Some cases are associated with thymoma. The hallmark of management is ...individualized immunosuppressive therapy.
Myasthenia gravis is an autoimmune disease in which antibodies bind to acetylcholine receptors or to functionally related molecules in the postsynaptic membrane at the neuromuscular junction. The antibodies induce weakness of skeletal muscles, which is the sole disease manifestation.
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The weakness can be generalized or localized, is more proximal than distal, and nearly always includes eye muscles, with diplopia and ptosis.
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The pattern of involvement is usually symmetric, apart from the eye involvement, which is often markedly asymmetric and involves several eye muscles. The weakness typically increases with exercise and repetitive muscle use (fatigue) and varies over the course . . .
Summary
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.
Complement is likely to have a role in refractory generalised myasthenia gravis, but no approved therapies specifically target this system. Results from a phase 2 study suggested that eculizumab, a ...terminal complement inhibitor, produced clinically meaningful improvements in patients with anti-acetylcholine receptor antibody-positive refractory generalised myasthenia gravis. We further assessed the efficacy and safety of eculizumab in this patient population in a phase 3 trial.
We did a phase 3, randomised, double-blind, placebo-controlled, multicentre study (REGAIN) in 76 hospitals and specialised clinics in 17 countries across North America, Latin America, Europe, and Asia. Eligible patients were aged at least 18 years, with a Myasthenia Gravis-Activities of Daily Living (MG-ADL) score of 6 or more, Myasthenia Gravis Foundation of America (MGFA) class II–IV disease, vaccination against Neisseria meningitides, and previous treatment with at least two immunosuppressive therapies or one immunosuppressive therapy and chronic intravenous immunoglobulin or plasma exchange for 12 months without symptom control. Patients with a history of thymoma or thymic neoplasms, thymectomy within 12 months before screening, or use of intravenous immunoglobulin or plasma exchange within 4 weeks before randomisation, or rituximab within 6 months before screening, were excluded. We randomly assigned participants (1:1) to either intravenous eculizumab or intravenous matched placebo for 26 weeks. Dosing for eculizumab was 900 mg on day 1 and at weeks 1, 2, and 3; 1200 mg at week 4; and 1200 mg given every second week thereafter as maintenance dosing. Randomisation was done centrally with an interactive voice or web-response system with patients stratified to one of four groups based on MGFA disease classification. Where possible, patients were maintained on existing myasthenia gravis therapies and rescue medication was allowed at the study physician's discretion. Patients, investigators, staff, and outcome assessors were masked to treatment assignment. The primary efficacy endpoint was the change from baseline to week 26 in MG-ADL total score measured by worst-rank ANCOVA. The efficacy population set was defined as all patients randomly assigned to treatment groups who received at least one dose of study drug, had a valid baseline MG-ADL assessment, and at least one post-baseline MG-ADL assessment. The safety analyses included all randomly assigned patients who received eculizumab or placebo. This trial is registered with ClinicalTrials.gov, number NCT01997229.
Between April 30, 2014, and Feb 19, 2016, we randomly assigned and treated 125 patients, 62 with eculizumab and 63 with placebo. The primary analysis showed no significant difference between eculizumab and placebo (least-squares mean rank 56·6 SEM 4·5 vs 68·3 4·5; rank-based treatment difference −11·7, 95% CI −24·3 to 0·96; p=0·0698). No deaths or cases of meningococcal infection occurred during the study. The most common adverse events in both groups were headache and upper respiratory tract infection (ten 16% for both events in the eculizumab group and 12 19% for both in the placebo group). Myasthenia gravis exacerbations were reported by six (10%) patients in the eculizumab group and 15 (24%) in the placebo group. Six (10%) patients in the eculizumab group and 12 (19%) in the placebo group required rescue therapy.
The change in the MG-ADL score was not statistically significant between eculizumab and placebo, as measured by the worst-rank analysis. Eculizumab was well tolerated. The use of a worst-rank analytical approach proved to be an important limitation of this study since the secondary and sensitivity analyses results were inconsistent with the primary endpoint result; further research into the role of complement is needed.
Alexion Pharmaceuticals.
Multiple sclerosis (MS) is a chronic debilitating disease of the central nervous system primarily mediated by T lymphocytes with specificity to neuronal antigens in genetically susceptible ...individuals. On the other hand, myasthenia gravis (MG) primarily involves destruction of the neuromuscular junction by antibodies specific to the acetylcholine receptor. Both autoimmune diseases are thought to result from loss of self-tolerance, which allows for the development and function of autoreactive lymphocytes. Although the mechanisms underlying compromised self-tolerance in these and other autoimmune diseases have not been fully elucidated, one possibility is numerical, functional, and/or migratory deficits in T regulatory cells (Tregs). Tregs are thought to play a critical role in the maintenance of peripheral immune tolerance. It is believed that Tregs function by suppressing the effector CD4+ T cell subsets that mediate autoimmune responses. Dysregulation of suppressive and migratory markers on Tregs have been linked to the pathogenesis of both MS and MG. For example, genetic abnormalities have been found in Treg suppressive markers CTLA-4 and CD25, while others have shown a decreased expression of FoxP3 and IL-10. Furthermore, elevated levels of pro-inflammatory cytokines such as IL-6, IL-17, and IFN-γ secreted by T effectors have been noted in MS and MG patients. This review provides several strategies of treatment which have been shown to be effective or are proposed as potential therapies to restore the function of various Treg subsets including Tr1, iTr35, nTregs, and iTregs. Strategies focusing on enhancing the Treg function find importance in cytokines TGF-β, IDO, interleukins 10, 27, and 35, and ligands Jagged-1 and OX40L. Likewise, strategies which affect Treg migration involve chemokines CCL17 and CXCL11. In pre-clinical animal models of experimental autoimmune encephalomyelitis (EAE) and experimental autoimmune myasthenia gravis (EAMG), several strategies have been shown to ameliorate the disease and thus appear promising for treating patients with MS or MG.
In patients with nonthymomatous myasthenia gravis, thymectomy plus prednisone was associated with better clinical outcomes than prednisone alone. Patients treated with thymectomy had fewer ...hospitalizations for exacerbations and required lower prednisone doses.
The first reported use of thymectomy in patients with nonthymomatous myasthenia gravis was 75 years ago.
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Of six patients who underwent surgery, three had a favorable response. Subsequent retrospective studies have shown benefits of thymectomy in patients with nonthymomatous myasthenia gravis but with widely varying rates of clinical improvement or remission. A compilation of retrospective studies comparing surgery with medical management did not show a difference in remission rates.
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Two studies that showed clinical improvements after thymectomy indicated that benefit occurred in the first few years after the procedure, but after 5 years, rates of clinical improvement were similar among . . .
Summary 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.
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