Immunopathology of Autoimmune Myasthenia Gravis: Implications for Improved Testing Algorithms and Treatment Strategies.

Myasthenia gravis (MG) is a heterogeneous condition, characterized by autoantibodies (Abs) that target functionally important structures within neuromuscular junctions (NMJ), thus affecting nerve-to-muscle transmission. MG patients are more often now subgrouped based on the profile of serum autoantibodies, which segregate with clinical presentation, immunopathology, and their response to therapies. The serological testing plays an essential role in confirming MG diagnosis and guiding disease management, although a small percentage of MG patients remain negative for antibodies. With the advancements in new highly effective pathophysiologically-specific immunotherapeutic options, it has become increasingly important to identify the specific Abs responsible for the pathogenicity in individual MG patients. There are several new assays and protocols being developed for the improved detection of Abs in MG patients. This review focuses on the divergent immunopathological mechanisms in MG, and discusses their relevance to improved diagnostic and treatment. We propose a comprehensive "reflex testing," algorithm for the presence of MG autoantibodies, and foresee that in the near future, the convenience and specificity of novel assays will permit the clinicians to consider them into routine systematic testing, thus stimulating laboratories to make these tests available. Moreover, adopting treatment driven testing algorithms will be crucial to identify subgroups of patients potentially benefiting from novel immunotherapies for MG.

Epidemiological evidence for a hereditary contribution to myasthenia gravis: a retrospective cohort study of patients from North America.

OBJECTIVES: To approximate the rate of familial myasthenia gravis and the coexistence of other autoimmune disorders in the patients and their families. DESIGN: Retrospective cohort study. SETTING: Clinics across North America. PARTICIPANTS: The study included 1032 patients diagnosed with acetylcholine receptor antibody (AChR)-positive myasthenia gravis. METHODS: Phenotype information of 1032 patients diagnosed with AChR-positive myasthenia gravis was obtained from clinics at 14 centres across North America between January 2010 and January 2011. A critical review of the epidemiological literature on the familial rate of myasthenia gravis was also performed. RESULTS: Among 1032 patients, 58 (5.6%) reported a family history of myasthenia gravis. A history of autoimmune diseases was present in 26.6% of patients and in 28.4% of their family members. DISCUSSION: The familial rate of myasthenia gravis was higher than would be expected for a sporadic disease. Furthermore, a high proportion of patients had a personal or family history of autoimmune disease. Taken together, these findings suggest a genetic contribution to the pathogenesis of myasthenia gravis.

Minimal manifestation status and prednisone withdrawal in the MGTX trial.

OBJECTIVE: To examine whether sustained minimal manifestation status (MMS) with complete withdrawal of prednisone is better achieved in thymectomized patients with myasthenia gravis (MG). METHODS: This study is a post hoc analysis of data from a randomized trial of thymectomy in MG (Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone Therapy [MGTX]). MGTX was a multicenter, randomized, rater-blinded 3-year trial that was followed by a voluntary 2-year extension for patients with acetylcholine receptor (AChR) antibody-positive MG without thymoma. Patients were randomized 1:1 to thymectomy plus prednisone vs prednisone alone. Participants were age 18-65 years at enrollment with disease duration less than 5 years. All patients received oral prednisone titrated up to 100 mg on alternate days until they achieved MMS, which prompted a standardized prednisone taper as long as MMS was maintained. The achievement rate of sustained MMS (no symptoms of MG for 6 months) with complete withdrawal of prednisone was compared between the thymectomy plus prednisone and prednisone alone groups. RESULTS: Patients with MG in the thymectomy plus prednisone group achieved sustained MMS with complete withdrawal of prednisone more frequently (64% vs 38%) and quickly compared to the prednisone alone group (median time 30 months vs no median time achieved, p < 0.001) over the 5-year study period. Prednisone-associated adverse symptoms were more frequent in the prednisone alone group and distress level increased with higher doses of prednisone. CONCLUSIONS: Thymectomy benefits patients with MG by increasing the likelihood of achieving sustained MMS with complete withdrawal of prednisone. CLINICALTRIALSGOV IDENTIFIER: NCT00294658. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that for patients with generalized MG with AChR antibody, those receiving thymectomy plus prednisone are more likely to attain sustained MMS and complete prednisone withdrawal than those on prednisone alone.

Causes that Contribute to the Excess Mortality Risk in Multiple Sclerosis: A Population-Based Study.

BACKGROUND: Lifespan is 6-10 years shorter in multiple sclerosis (MS), but the reasons remain unclear. Using linked clinical- and population-based administrative health databases, we compared cause-specific mortality in an MS cohort to the general population. METHODS: MS patients in British Columbia (BC), Canada, were followed from the later of first MS clinic visit or January 1, 1986, to the earlier of death, emigration, or December 31, 2013. Comprehensive mortality information was obtained by linkage to BC's multiple-cause-of-death mortality data. Causes were grouped using International Classification of Disease codes. Standardized mortality ratios (SMRs) were calculated for underlying cause, and relative mortality ratios (RMRs) for any mention cause, by comparison to mortality rates in the age-, sex-, and calendar year-matched general population. Cause-specific relative mortality was explored by sex and disease course (relapsing onset and primary progressive). RESULTS: Among 6,629 MS patients with 104,236 patient-years of follow-up, 1,416 died. The all-cause mortality risk was increased relative to the general population (SMR 2.71; 95% CI 2.55-2.87). MS was the underlying cause in 50.4%, and a mentioned cause in 77.9%, of deaths. Mortality by underlying cause was higher than expected for genitourinary disorders/infections (SMR 3.55; 95% CI 2.25-5.32), respiratory diseases/infections (SMR 2.69; 95% CI 2.17-3.28), suicide (SMR 2.40; 95% CI 1.61-3.45), cardiovascular disease (SMR 1.57; 95% CI 1.36-1.81), and other infections/septicemia (SMR 1.83; 95% CI 1.15-2.78). Risks of death due to overall cancer, accidents, digestive system disorders, and endocrine/nutritional diseases as underlying causes were similar to the general population. However, mortality with any mention of accidents (RMR 2.71; 95% CI 2.22-3.29) or endocrine/nutritional diseases (RMR 1.75; 95% CI 1.46-2.09) was greater. Bladder cancer mortality was increased in women (SMR 3.87; 95% CI 1.42-8.42) but not men. No notable differences were observed by disease course. CONCLUSIONS: MS itself was the most frequent underlying cause of death. Infections (genitourinary, respiratory, and septicemia), suicides, cardiovascular disease, and accidents contributed significantly to the increased risk of death. Some findings differed by sex, but not disease course. Multiple-cause death data offer advantages over "traditional" use of underlying cause only.

Multiple sclerosis: effect of beta interferon treatment on survival.

Worldwide, the beta interferons remain the most commonly prescribed disease-modifying drugs for multiple sclerosis. However, it is unclear if they alter survival. We investigated the association between beta interferon and mortality in the 'real-world' setting. This was a multi-centre population-based observational study of patients with relapsing-onset multiple sclerosis who were initially registered at a clinic in British Columbia, Canada (1980-2004) or Rennes, France (1976-2013). Data on this cohort were accessed from the clinical multiple sclerosis databases and from individually linked health administrative data; all data were collected prospectively. Participants were followed from the latter of their first multiple sclerosis clinic visit, 18th birthday or 1 January 1996; until death, emigration or 31 December 2013. Only those who were naïve to disease-modifying therapy and immunosuppressant treatment of multiple sclerosis at the start of their follow-up were included in the analysis. A nested case-control approach was used. Up to 20 controls, matched to cases (deaths) by country, sex, age ± 5 years, year and disability level at study entry, were randomly selected from the cohort by incidence density sampling. The associations between all-cause mortality and at least 6 months beta interferon exposure, and also cumulative exposure ('low', 6 months to 3 years; and 'high', >3 years), were estimated by conditional logistic regression adjusting for treatment with other disease-modifying therapies and age in years. Further analyses included separate analyses by sex and country, additional adjustment for comorbidity burden in the Canadian cohort, and estimation of the association between beta interferon and multiple sclerosis-related death in both countries. Among 5989 participants (75% female) with a mean age of 42 (standard deviation, SD 11) years at study entry, there were 742 deaths (70% female) and the mean age at death was 61 (SD 13) years. Of these cases, 649 were matched to between one and 20 controls. Results of the conditional logistic regression analyses are expressed as adjusted odds ratios with 95% confidence intervals. The odds of beta interferon exposure were 32% lower among cases than controls (0.68; 0.53-0.89). Increased survival was associated with >3 years beta interferon exposure (0.44; 0.30-0.66), but not between 6 months and 3 years exposure (1.00; 0.73-1.38). Findings were similar within sex and country, and for multiple sclerosis-related death. Beta interferon treatment was associated with a lower mortality risk among people with relapsing-onset multiple sclerosis. Findings were consistent between two geographically distinct regions in North America and Europe.

Long-term effect of thymectomy plus prednisone versus prednisone alone in patients with non-thymomatous myasthenia gravis: 2-year extension of the MGTX randomised trial.

BACKGROUND: The Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone (MGTX) showed that thymectomy combined with prednisone was superior to prednisone alone in improving clinical status as measured by the Quantitative Myasthenia Gravis (QMG) score in patients with generalised non-thymomatous myasthenia gravis at 3 years. We investigated the long-term effects of thymectomy up to 5 years on clinical status, medication requirements, and adverse events. METHODS: We did a rater-blinded 2-year extension study at 36 centres in 15 countries for all patients who completed the randomised controlled MGTX and were willing to participate. MGTX patients were aged 18 to 65 years at enrolment, had generalised non-thymomatous myasthenia gravis of less than 5 years' duration, had acetylcholine receptor antibody titres of 1·00 nmol/L or higher (or concentrations of 0·50-0·99 nmol/L if diagnosis was confirmed by positive edrophonium or abnormal repetitive nerve stimulation, or abnormal single fibre electromyography), had Myasthenia Gravis Foundation of America Clinical Classification Class II-IV disease, and were on optimal anticholinesterase therapy with or without oral corticosteroids. In MGTX, patients were randomly assigned (1:1) to either thymectomy plus prednisone or prednisone alone. All patients in both groups received oral prednisone at doses titrated up to 100 mg on alternate days until they achieved minimal manifestation status. The primary endpoints of the extension phase were the time-weighted means of the QMG score and alternate-day prednisone dose from month 0 to month 60. Analyses were by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT00294658. It is closed to new participants, with follow-up completed. FINDINGS: Of the 111 patients who completed the 3-year MGTX, 68 (61%) entered the extension study between Sept 1, 2009, and Aug 26, 2015 (33 in the prednisone alone group and 35 in the prednisone plus thymectomy group). 50 (74%) patients completed the 60-month assessment, 24 in the prednisone alone group and 26 in the prednisone plus thymectomy group. At 5 years, patients in the thymectomy plus prednisone group had significantly lower time-weighted mean QMG scores (5·47 [SD 3·87] vs 9·34 [5·08]; p=0·0007) and mean alternate-day prednisone doses (24 mg [SD 21] vs 48 mg [29]; p=0·0002) than did those in the prednisone alone group. 14 (42%) of 33 patients in the prednisone group, and 12 (34%) of 35 in the thymectomy plus prednisone group, had at least one adverse event by month 60. No treatment-related deaths were reported during the extension phase. INTERPRETATION: At 5 years, thymectomy plus prednisone continues to confer benefits in patients with generalised non-thymomatous myasthenia gravis compared with prednisone alone. Although caution is appropriate when generalising our findings because of the small sample size of our study, they nevertheless provide further support for the benefits of thymectomy in patients with generalised non-thymomatous myasthenia gravis. FUNDING: National Institutes of Health, National Institute of Neurological Disorders and Stroke.

Predictive validity of NEDA in the 16- and 21-year follow-up from the pivotal trial of interferon beta-1b.

BACKGROUND: Long-term follow-up from the randomized trial of interferon beta-1b (IFNB-1b) permitted the assessment of different definitions of no evidence of disease activity (NEDA) for predicting long-term outcome in multiple sclerosis (MS). OBJECTIVE: To examine the predictive validity of different NEDA definitions. METHODS: Predictive validity for negative disability outcomes (NDOs) at 16 years and survival at 21 years post-randomization were assessed. NEDA in the first 2 years was defined as follows: clinical NEDA: no relapses or Expanded Disability Status Scale (EDSS) progression from baseline to Year 2; NEDA-3a: no relapses, no confirmed ⩾1-point EDSS progression, and no new T2-active lesions; NEDA-3b: no relapses, no EDSS progression, and no increase in T2 burden of disease (T2-BOD); and NEDA-4: no relapses, no EDSS progression, and no increase in T2-BOD or atrophy. NDOs were defined as death, need for wheelchair, EDSS ⩾6, or progressive MS. RESULTS: A total of 245 and 371 patients were evaluated at 16 and 21 years, respectively. Clinical NEDA predicted NDOs ( p = 0.0029), as did baseline EDSS ( p < 0.0001), baseline T2-BOD ( p < 0.0001), and change in T2-BOD ( p = 0.0033). IFNB-1b treatment ( p = 0.0251), relapse rate in the 2 years before study start ( p = 0.0260), T2-BOD at baseline ( p = 0.0014), and change in T2-BOD ( p = 0.0129) predicted survival at 21 years. CONCLUSION: Clinical NEDA predicted long-term disability outcome. By contrast, definitions of NEDA that included on-therapy changes in magnetic resonance imaging variables did not increase the predictive validity.

Assessing the long-term effectiveness of interferon-beta and glatiramer acetate in multiple sclerosis: final 10-year results from the UK multiple sclerosis risk-sharing scheme.

BACKGROUND: Because multiple sclerosis (MS) is a chronic disease causing disability over decades, it is crucial to know if the short-term effects of disease-modifying therapies reported in randomised controlled trials reduce long-term disability. This 10-year prospective observational study of disability outcomes (Expanded Disability Status Scale (EDSS) and utility) was set up, in conjunction with a risk-sharing agreement between payers and producers, to investigate this issue. METHODS: The outcomes of the UK treated patients were compared with a modelled untreated control based on the British Columbia MS data set to assess the long-term effectiveness of these treatments. Two complementary analysis models were used: a multilevel model (MLM) and a continuous Markov model. RESULTS: 4862 patients with MS were eligible for the primary analysis (mean and median follow-up times 8.7 and 10 years). EDSS worsening was reduced by 28% (MLM), 7% (Markov) and 24% time-adjusted Markov in the total cohort, and by 31% (MLM) and 14% (Markov) for relapsing remitting patients. The utility worsening was reduced by 23%-24% in the total cohort and by 24%-31% in the RR patients depending on the model used. All sensitivity analyses showed a treatment effect. There was a 4-year (CI 2.7 to 5.3) delay to EDSS 6.0. An apparent waning of treatment effect with time was seen. Subgroup analyses suggested better treatment effects in those treated earlier and with lower EDSS scores. CONCLUSIONS: This study supports a beneficial effect on long-term disability with first-line MS disease-modifying treatments, which is clinically meaningful. However the waning effect noted requires further study.

Disability progression in aggressive multiple sclerosis.

OBJECTIVE: To examine disease progression in 'aggressive' multiple sclerosis (MS), British Columbia, Canada (1980-2009). METHODS: Aggressive (or 'malignant') MS was defined as Expanded Disability Status Scale (EDSS) ⩾6 within 5 years from onset. The first EDSS ⩾6 was termed 'baseline'. Within 2, 3 and 5 years post-baseline, patients were categorized as follows: 'worsened' or 'improved', relative to baseline EDSS (the remainder exhibited no change or had no new scores). The associations between patient characteristics (sex, relapsing onset/primary progressive, onset age, onset symptoms, disease duration, cumulative prior relapses and baseline EDSS) and worsening in disability were examined longitudinally using logistic regression. RESULTS: Of the 225/4341 (5.2%) aggressive/malignant MS patients, 134 (59.6%) were female, 167 (74.2%) were relapsing onset, 94 (41.8%) had received disease-modifying drugs at some point and the mean follow-up was 8.7 years. The proportion of patients who 'worsened' increased from 40.4% to 57.8%, while those who 'improved' varied little (range, 8.9%-10.2%). The odds of worsening increased with disease duration (adjusted odds ratio (AOR) = 1.36; 95% confidence interval (CI) = 1.22-1.52) and the presence of primary progressive (vs relapsing-onset) MS (AOR = 1.85; 95% CI = 1.01-3.38). CONCLUSION: Apart from disease duration and a primary progressive course, no clinically useful associations of subsequent disease worsening in patients with aggressive/malignant MS were identified.

Modelling disease progression in relapsing-remitting onset multiple sclerosis using multilevel models applied to longitudinal data from two natural history cohorts and one treated cohort.

BACKGROUND: The ability to better predict disease progression represents a major unmet need in multiple sclerosis (MS), and would help to inform therapeutic and management choices. OBJECTIVES: To develop multilevel models using longitudinal data on disease progression in patients with relapsing-remitting MS (RRMS) or secondary-progressive MS (SPMS); and to use these models to estimate the association of disease-modifying therapy (DMT) with progression. DESIGN: Secondary analysis of three MS cohorts. SETTING: Two natural history cohorts: University of Wales Multiple Sclerosis (UoWMS) cohort, UK, and British Columbia Multiple Sclerosis (BCMS) cohort, Canada. One observational DMT-treated cohort: UK MS risk-sharing scheme (RSS). PARTICIPANTS: The UoWMS database has > 2000 MS patients and the BCMS database (as of 2009) has > 5900 MS patients. All participants who had definite MS (RRMS/SPMS), who reached the criteria set out by the Association of British Neurologists (ABN) for eligibility for DMT [i.e. age ≥ 18 years, Expanded Disability Status Scale (EDSS) score of ≤ 6.5, occurrence of two or more relapses in the previous 2 years] and who had at least two repeated outcome measures were included: 404 patients for the UoWMS cohort and 978 patients for the BCMS cohort. Through the UK MS RSS scheme, 5583 DMT-treated patients were recruited, with the analysis sample being the 4137 who had RRMS and were eligible and treated at baseline, with at least one valid EDSS score post baseline. MAIN OUTCOME MEASURES: EDSS score observations post ABN eligibility. METHODS: We used multilevel models in the development cohort (UoWMS) to develop a model for EDSS score with time since ABN eligibility, allowing for covariates and appropriate transformation of outcome and/or time. These methods were then applied to the BCMS cohort to obtain a 'natural history' model for changes in the EDSS score with time. We then used this natural history model to predict the trajectories of EDSS score in treated patients in the UK MS RSS database. Differences between the progression predicted by the natural history model and the progression observed at 6 years' follow-up for the UK MS RSS cohort were used as indicators of the effectiveness of the DMTs. Previously developed utility scores were assigned to each EDSS score, and differences in utility also examined. RESULTS: The model best fitting the UoWMS data showed a non-linear increase in EDSS score over time since ABN eligibility. This model fitted the BCMS cohort data well, with similar coefficients, and the BCMS model predicted EDSS score in UoWMS data with little evidence of bias. Using the natural history model predicts EDSS score in a treated cohort (UK MS RSS) higher than that observed [by 0.59 points (95% confidence interval 0.54 to 0.64 points)] at 6 years post treatment. LIMITATIONS: Only two natural history cohorts were compared, limiting generalisability. The comparison of a treated cohort with untreated cohorts is observational, thus limiting conclusions about causality. CONCLUSIONS: EDSS score progression in two natural history cohorts of MS patients showed a similar pattern. Progression in the natural history cohorts was slightly faster than EDSS score progression in the DMT-treated cohort, up to 6 years post treatment. FUTURE WORK: Long-term follow-up of randomised controlled trials is needed to replicate these findings and examine duration of any treatment effect. FUNDING DETAILS: The National Institute for Health Research Health Technology Assessment programme.

Randomized Trial of Thymectomy in Myasthenia Gravis.

BACKGROUND: Thymectomy has been a mainstay in the treatment of myasthenia gravis, but there is no conclusive evidence of its benefit. We conducted a multicenter, randomized trial comparing thymectomy plus prednisone with prednisone alone. METHODS: We compared extended transsternal thymectomy plus alternate-day prednisone with alternate-day prednisone alone. Patients 18 to 65 years of age who had generalized nonthymomatous myasthenia gravis with a disease duration of less than 5 years were included if they had Myasthenia Gravis Foundation of America clinical class II to IV disease (on a scale from I to V, with higher classes indicating more severe disease) and elevated circulating concentrations of acetylcholine-receptor antibody. The primary outcomes were the time-weighted average Quantitative Myasthenia Gravis score (on a scale from 0 to 39, with higher scores indicating more severe disease) over a 3-year period, as assessed by means of blinded rating, and the time-weighted average required dose of prednisone over a 3-year period. RESULTS: A total of 126 patients underwent randomization between 2006 and 2012 at 36 sites. Patients who underwent thymectomy had a lower time-weighted average Quantitative Myasthenia Gravis score over a 3-year period than those who received prednisone alone (6.15 vs. 8.99, P<0.001); patients in the thymectomy group also had a lower average requirement for alternate-day prednisone (44 mg vs. 60 mg, P<0.001). Fewer patients in the thymectomy group than in the prednisone-only group required immunosuppression with azathioprine (17% vs. 48%, P<0.001) or were hospitalized for exacerbations (9% vs. 37%, P<0.001). The number of patients with treatment-associated complications did not differ significantly between groups (P=0.73), but patients in the thymectomy group had fewer treatment-associated symptoms related to immunosuppressive medications (P<0.001) and lower distress levels related to symptoms (P=0.003). CONCLUSIONS: Thymectomy improved clinical outcomes over a 3-year period in patients with nonthymomatous myasthenia gravis. (Funded by the National Institute of Neurological Disorders and Stroke and others; MGTX ClinicalTrials.gov number, NCT00294658.).

Association between the use of selective serotonin reuptake inhibitors and multiple sclerosis disability progression.

BACKGROUND: Benefits of selective serotonin reuptake inhibitors (SSRIs) in modifying the multiple sclerosis (MS) disease course have been suggested, but their ability to delay disability progression remains unknown. We examined the association between SSRI exposure and MS disability progression. METHODS: A nested case-control study was conducted using the British Columbia (Canada) Multiple Sclerosis clinical data linked to health administrative data. The primary outcome was a sustained score of 6 (requires a cane to walk) on the Expanded Disability Status Scale (EDSS), and the secondary outcome was the onset of secondary progressive MS (SPMS, an advanced stage of MS). The cases were those who reached a study outcome and were matched with up to four randomly selected controls by sex, age, EDSS and calendar year at study entry using incidence density sampling. The associations between disability worsening and SSRI exposure were assessed with conditional logistic regression models, adjusted for confounders. RESULTS: A total of 3920 patients were included in the main analyses, of which 272 reached sustained EDSS 6 and 187 reached SPMS. SSRI exposure was significantly different between patients who reached sustained EDSS 6 and controls [adjusted odds ratio (adjOR):1.44; 95% confidence interval (CI):1.03-2.01]. However, SSRI exposure was not significantly different between those who reached SPMS and their controls (adjOR:1.35; 95%CI:0.89-2.04). CONCLUSION: We found no evidence to suggest that SSRI exposure was associated with a delay in MS disability accumulation or progression. Copyright © 2016 John Wiley & Sons, Ltd.

Treatment of Myasthenia Gravis in the Aged.

Myasthenia gravis is diagnosed at a progressively later age and the incidence continuously increases in the aged with a clear male predominance. People above the age of 65 constitute more than 50% of the newly diagnosed. Commonly, patients present with focal (ocular or bulbar) weakness. A high index of suspicion is needed to achieve early diagnosis and improve prognosis. Management options include acetylcholinesterase inhibitors, steroids, and immunosuppressants. Of the immunosuppressants, azathioprine is one of the most widely used due to its demonstrated effect and favorable side-effect profile. Others include cyclosporine, tacrolimus, mycophenolate mofetil, and cyclophosphamide. The use of mycophenolate mofetil is still controversial. Monoclonal antibodies, like rituximab, eculizumab, and belimumab, are relatively new therapeutic options in autoimmune diseases. Rituximab is of special interest in muscle-specific tyrosine kinase antibody-positive patients. A novel skeletal muscle activator and stem cell transplantation are being studied. There is no place for standard thymectomy in the older age groups except for thymomas and with computer-assisted endoscopy. Generally, the disease responds well to treatment at this age but comorbidities make medication choice more complex. Successful treatment is associated with improved survival, and quality of life can be remarkably improved during the whole survival period. As the median age of onset is 65 years and has been increasing steadily, it appears necessary to review the subject of treatment of myasthenia gravis in the aged.

An update on laboratory diagnosis in myasthenia gravis.

This review describes the state of the art for the use of laboratory testing in myasthenia gravis. The review brings a detailed description of the different clinical forms of auto-immune myasthenia and of the Lambert Eaton Myasthenic Syndrome (LEMS). They stress the differences between the different forms of acquired (auto-immune) myasthenia. Then they present a summary of the different antibodies found in the disease. They insist on the advantage of the RIPA assay to measure antibodies to the acetylcholine receptor. They stress the different types of contribution of each of these antibodies to the clinical diagnosis. They also describe the methods to measure each of the specific antibodies that have recently permitted to split the diagnosis: Abs to omega-conotoxin receptor in Lambert Eaton Myasthenic Syndrome (LEMS), abs to the acetylcholine receptor (AchR) in MG, Abs to muscle specific tyrosine kinase (MuSK) in Ab negative MG, and Abs to low molecular weight receptor related low-density lipo protein-4 (LRP-4). They also broach over the striated antibodies, less frequent and clinically less useful such as anti-titin, -ryanodine, -agrin and -rapsyn. This represent a 360° view of the field as presented in Toronto in October 2014.

Amyotrophic lateral sclerosis presentation of a human T-lymphotropic virus type-1 myelopathy--insight into pathogenesis.

A 41-year-old human T-lymphotropic virus type 1-positive woman developed a syndrome with upper and lower motor neuron signs sometime after bilateral vertebral artery dissections. Over 2 years, she developed a progressive myelopathy affecting predominantly the motor system. She had the picture of a 'person in a barrel' and died from complications. At autopsy, spinal cord revealed inflammatory infiltrates and extensive gliosis involving mainly the anterior horns. The vertebral arterial dissections may have permitted the entry of infected lymphocytes and macrophages, secreting cytokines and metalloproteinases, into the medulla progressing to the spinal cord. Few cases with pathological correlation have been reported.

A longitudinal model for disease progression was developed and applied to multiple sclerosis.

OBJECTIVES: To develop a model of disease progression using multiple sclerosis (MS) as an exemplar. STUDY DESIGN AND SETTINGS: Two observational cohorts, the University of Wales MS (UoWMS), UK (1976), and British Columbia MS (BCMS) database, Canada (1980), with longitudinal disability data [the Expanded Disability Status Scale (EDSS)] were used; individuals potentially eligible for MS disease-modifying drugs treatments, but who were unexposed, were selected. Multilevel modeling was used to estimate the EDSS trajectory over time in one data set and validated in the other; challenges addressed included the choice and function of time axis, complex observation-level variation, adjustments for MS relapses, and autocorrelation. RESULTS: The best-fitting model for the UoWMS cohort (404 individuals, and 2,290 EDSS observations) included a nonlinear function of time since onset. Measurement error decreased over time and ad hoc methods reduced autocorrelation and the effect of relapse. Replication within the BCMS cohort (978 individuals and 7,335 EDSS observations) led to a model with similar time (years) coefficients, time [0.22 (95% confidence interval {CI}: 0.19, 0.26), 0.16 (95% CI: 0.10, 0.22)] and log time [-0.13 (95% CI: -0.39, 0.14), -0.15 (95% CI: -0.70, 0.40)] for BCMS and UoWMS, respectively. CONCLUSION: It is possible to develop robust models of disability progression for chronic disease. However, explicit validation is important given the complex methodological challenges faced.

Multiple sclerosis in older adults: the clinical profile and impact of interferon Beta treatment.

BACKGROUND: We examined (1) patient characteristics and disease-modifying drug (DMD) exposure in late-onset (LOMS, ≥50 years at symptom onset) versus adult-onset (AOMS, 18-<50 years) MS and (2) the association between interferon-beta (IFNß) and disability progression in older relapsing-onset MS adults (≥50 years). METHODS: This retrospective study (1980-2004, British Columbia, Canada) included 358 LOMS and 5627 AOMS patients. IFNß-treated relapsing-onset MS patients aged ≥50 (regardless of onset age, 90) were compared with 171 contemporary and 106 historical controls. Times to EDSS 6 from onset and from IFNß eligibility were examined using survival analyses. RESULTS: LOMS patients (6%) were more likely to be male, with motor onset and a primary-progressive course, and exhibit faster progression and were less likely to take DMDs. Nonetheless, 57% were relapsing-onset, of which 31% were prescribed DMDs, most commonly IFNß. Among older relapsing-onset MS adults, no significant association between IFNß exposure and disability progression was found when either the contemporary (hazard ratio [HR]: 0.46; 95% CI: 0.18-1.22) or historical controls (HR: 0.54; 95% CI: 0.20-1.42) were considered. CONCLUSION: LOMS differed clinically from AOMS. One-third of older relapsing-onset MS patients were prescribed a DMD. IFNß exposure was not significantly associated with reduced disability in older MS patients.

Effectiveness and cost-effectiveness of interferon beta and glatiramer acetate in the UK Multiple Sclerosis Risk Sharing Scheme at 6 years: a clinical cohort study with natural history comparator.

BACKGROUND: In 2002, the UK's National Institute for Clinical Excellence (NICE) concluded that interferon beta and glatiramer acetate would be cost effective as disease-modifying therapies (DMTs) for multiple sclerosis only if the short-term disability benefits reported in clinical trials were maintained. The UK Multiple Sclerosis Risk Sharing Scheme (RSS) was established to assess whether disability progression was consistent with a cost-effectiveness target of £36 000 per quality-adjusted life-year projected over 20 years. We aimed to evaluate the long-term effectiveness and cost-effectiveness of these DMTs by comparing a cohort of patients with relapsing-remitting multiple sclerosis enrolled in the UK RSS with a natural history cohort from British Columbia, Canada. METHODS: In our clinical cohort we included patients starting a DMT who were enrolled in the UK RSS who had relapsing multiple sclerosis at baseline and had at least one further clinical assessment. In our control cohort we included patients in the British Columbia multiple sclerosis database (BCMS; data collection 1980-96) who met the same eligibility criteria as for the RSS cohort. We compared disability progression at 6 years for RSS patients with untreated progression modelled from BCMS patients using continuous Markov and multilevel models. The primary outcomes were the progression ratio (treated vs untreated) measured both in Expanded Disability Status Scale (EDSS) score and utility. A ratio of less than 100% for EDSS implied slower than expected progression on treatment compared with off treatment; a utility ratio of 62% or less implied that the DMTs were cost effective. FINDINGS: 5610 patients starting a DMT were enrolled in the UK RSS between Jan 14, 2002, and July 13, 2005 (72 sites), of whom 4137 were included in our clinical cohort. We included 898 BCMS patients in the control cohort who met the RSS inclusion criteria and had at least one EDSS score after baseline. RSS patients had a mean follow-up of 5·1 years (SD 1·4). Both models showed slower EDSS progression than predicted for untreated controls (Markov model, 75·8% [95% CI 71·4-80·2]; multilevel model, 60·0% [56·6-63·4]). Utility ratios were consistent with cost-effectiveness (Markov model, 58·5% [95% CI 54·2-62·8]; multilevel model, 57·1% [53·0-61·2]). INTERPRETATION: Findings from this large observational study of treatment with interferon beta or glatiramer acetate provide evidence that their effects on disability in patients with relapsing-remitting multiple sclerosis are maintained and cost effective over 6 years. Similar modelling approaches could be applied to other chronic diseases for which long-term controlled trials are not feasible. FUNDING: Health Departments of England, Wales, Scotland, and Northern Ireland, Biogen Idec, Merck Serono, Bayer Schering Pharmaceuticals, Teva Pharmaceuticals Industries, UK National Institute of Health Research's Health Technology Assessment Programme.

Serum proteomics in multiple sclerosis disease progression.

Multiple sclerosis (MS) is associated with chronic degeneration of the central nervous system and may cause permanent neurological problems and considerable disability. While its causes remain unclear, its extensive phenotypic variability makes its prognosis and treatment difficult. The identification of serum proteomic biomarkers of MS progression could further our understanding of the molecular mechanisms related to MS disease processes. In the current study, we used isobaric tagging for relative and absolute protein quantification (iTRAQ) methodology and advanced multivariate statistical analysis to quantify and identify potential serum biomarker proteins of MS progression. We identified a panel of 11 proteins and combined them into a classifier that best classified samples into the two disease groups. The estimated area under the receiver operating curve of this classifier was 0.88 (p-value=0.017), with 86% sensitivity and specificity. The identified proteins encompassed processes related to inflammation, opsonization, and complement activation. Results from this study are in particular valuable to design a targeted Multiple Reaction Monitoring mass spectrometry based (MRM-MS) assay to conduct an external validation in an independent and larger cohort of patients. Validated biomarkers may result in the development of a minimally-invasive tool to monitor MS progression and complement current clinical practices. BIOLOGICAL SIGNIFICANCE: A hallmark of multiple sclerosis is the unpredictable disease course (progression). There are currently no clinically useful biomarkers of MS disease progression; most work has focused on the analysis of CSF, which requires an invasive procedure. Here, we explore the potential of proteomics to identify panels of serum biomarkers of disease progression in MS. By comparing the protein signatures of two challenging to obtain, but well-defined, MS phenotypic groups at the extremes of progression (benign and aggressive cases of MS), we identified proteins that encompass processes related to inflammation, opsonization, and complement activation. Findings require validation, but are an important step on the pathway to clinically useful biomarker discovery. This article is part of a Special Issue entitled: Protein dynamics in health and disease. Guest Editors: Pierre Thibault and Anne-Claude Gingras.

An update on laboratory diagnosis in myasthenia gravis.

This review describes the state of the art for the use of laboratory testing in myasthenia gravis. The review brings a detailed description of the different clinical forms of auto-immune myasthenia and of the Lambert Eaton Myasthenic Syndrome (LEMS). The stress the differences between the different forms of acquired (auto-immune) myasthenia. Then they present a summary of the different antibodies found in the disease. They insist on the advantage of the RIPA assay to measure antibodies to the acetylcholine receptor. They stress the different types of contribution of each of these antibodies to the clinical diagnosis. They also describe the methods to measure each of the specific antibodies that have recently permitted to split the diagnosis: Abs to omega-conotoxin receptor in Lambert Eaton Myasthenic Syndrome (LEMS), abs to the acetylcholine receptor (AchR) in MG, Abs to muscle specific tyrosine kinase (MuSK) in Ab negative MG, and Abs to low molecular weight receptor related low-density lipo protein-4 (LRP-4). They also broach over the striated antibodies, less frequent and clinically less useful such as anti-titin, -ryanodine, -agrin and -rapsyn. This represent a 360° view of the field as presented in Toronto in October 2014.