Mycophenolate and methotrexate are better tolerated than azathioprine in myasthenia gravis.

Azathioprine is recommended as the first-line steroid-sparing immunosuppressive agent for myasthenia gravis. Mycophenolate and methotrexate are often considered as second-line choices despite widespread consensus on their efficacy. We aimed to gather real-world data comparing the tolerability and reasons for discontinuation for these agents, by performing a national United Kingdom survey of side effects and reasons for discontinuation of immunosuppressants in myasthenia gravis. Of 235 patients, 166 had taken azathioprine, 102 mycophenolate, and 40 methotrexate. The most common side effects for each agent were liver dysfunction for azathioprine (23 %), diarrhoea for mycophenolate (14 %), and fatigue for methotrexate (18 %). Women were generally more likely to experience side effects of immunosuppressants. Azathioprine was significantly more likely to be discontinued than mycophenolate and methotrexate due to side effects. There was no significant difference in treatment cessation due to lack of efficacy. This study highlights the significant side-effect burden of treatment for myasthenia gravis. Mechanisms to reduce azathioprine toxicity should be utilised, however mycophenolate and methotrexate appear to be good treatment choices if teratogenicity is not a concern. Women are disadvantaged due to higher frequency of side effects and considerations around pregnancy and breastfeeding. Treatments with improved tolerability are needed.

Complement activation profiles in anti-acetylcholine receptor positive myasthenia gravis.

BACKGROUND AND PURPOSE: Complement component 5 (C5) targeting therapies are clinically beneficial in patients with acetylcholine receptor antibody+ (AChR-Ab+ ) generalized myasthenia gravis (MG). That clearly implicates antibody-mediated complement activation in MG pathogenesis. Here, classical and alternative complement pathways were profiled in patients from different MG subgroups. METHODS: In a case-control study, concentrations of C3a, C5a and sC5b9 were simultaneously quantified, indicating general activation of the complement system, whether via the classical and lectin pathways (C4a) or the alternative pathway (factors Ba and Bb) in MG patients with AChR or muscle-specific kinase antibodies (MuSK-Abs) or seronegative MG compared to healthy donors. RESULTS: Treatment-naïve patients with AChR-Ab+ MG showed substantially increased plasma levels of cleaved complement components, indicating activation of the classical and alternative as well as the terminal complement pathways. These increases were still present in a validation cohort of AChR-Ab+ patients under standard immunosuppressive therapies; notably, they were not evident in patients with MuSK-Abs or seronegative MG. Neither clinical severity parameters (at the time of sampling or 1 year later) nor anti-AChR titres correlated significantly with activated complement levels. CONCLUSIONS: Markers indicative of complement activation are prominently increased in patients with AChR-Ab MG despite standard immunosuppressive therapies. Complement inhibition proximal to C5 cleavage should be explored for its potential therapeutic benefits in AChR-Ab+ MG.

Lung cancer prediction in Lambert-Eaton myasthenic syndrome in a prospective cohort.

To evaluate the Dutch-English Lambert-Eaton Myasthenic Syndrome (LEMS) Tumour Association Prediction (DELTA-P) score in a prospective cohort of patients with newly diagnosed LEMS to assess the clinical validity of this tool in a real-world setting. Clinical features from 87 patients with LEMS, occurring within three months from disease onset, were collated to produce a DELTA-P score for each patient. Lung cancer was detected in 44/87 (51%) LEMS patients. Weight loss ≥ 5%, tobacco use at LEMS onset and age at onset ≥ 50 years were independent predictors for the development of small-cell lung cancer (SCLC) in LEMS patients in multivariable analysis. Median DELTA-P scores were significantly higher in SCLC-LEMS patients (3.5, 95% CI 3 to 4) compared to non-tumour-LEMS (2, 95% CI 1 to 2) (P < 0.0001). Higher DELTA-P scores increased the risk of SCLC stepwise (score 0 = 0%, 1 = 18.8%, 2 = 45%, 3 = 55.5%, 4 = 85.7%, 5 = 87.5%, 6 = 100%). The area under the curve of the receiver operating curve was 82.5% (95% CI 73.9% to 91%). The DELTA-P cancer prediction score, calculated at the time of LEMS diagnosis, is an effective tool for cancer screening in an independent, prospective study setting.

Neuronal antibody detection and improved lung cancer prediction in Lambert-Eaton myasthenic syndrome.

Since approximately 50% of patients with Lambert-Eaton myasthenic syndrome (LEMS) subsequently develop small-cell lung cancer (SCLC), it is important to be able to predict cancer occurrence in these patients at neurological presentation. We aimed to determine whether circulating biomarkers were effective and objective predictors of cancer development in LEMS. We found that the presence of either SOX2, N-type voltage gated calcium channel or GABAb antibodies at LEMS diagnosis was highly sensitive (84%) and specific (87%) for the detection of SCLC. Screening for SOX2 and neuronal antibodies is a useful adjunct to clinical predictive scoring tools in predicting SCLC in LEMS.

A Prospective Study of the Incidence of Myasthenia Gravis in the East Midlands of England.

OBJECTIVES: A number of worldwide studies have highlighted a rising incidence of myasthenia gravis (MG) over the past few decades. This is largely due to an increase in numbers in older patients. To establish whether this was a consistent finding in the United Kingdom, we conducted a large, 4-year prospective cohort study of all known patients with new-onset MG in the East Midlands of the United Kingdom. METHODS: Between 2014 and 2018, all 120 patients with a new diagnosis of MG who were residing in the East Midlands were enrolled. RESULTS: Median age at disease onset was 63 years (78% aged over 50 years) and most patients (57%) were male. The average annual incidence rate (IR) was 17.6/1,000,000 (95% CI 10.7-28.6). IRs remained stable between 2014 and 2018 except for rising IRs in patients over 65 years of age (p value for trend, <0.001). CONCLUSIONS: Twenty years after the last comprehensive prospective incidence survey of MG in the east of England, we have demonstrated a rising incidence. The greatest increases seen were in patients over 65 years. Given the rigorous study methods employed, future replicate prospective studies from the same region will establish whether these rising figures are due to biological factors, independent of improved case ascertainment.

False-positive acetylcholine receptor antibody results in patients without myasthenia gravis.

Acetylcholine receptor antibodies are very specific for myasthenia. During a large prospective cohort study of myasthenia, we encountered five patients, positive for acetylcholine receptor (AChR) antibodies by radioimmunoprecipitation assay (RIA), whose clinical course revealed diagnoses other than myasthenia. Two patients had transiently raised AChR antibodies associated with Guillain-Barré syndrome. Antibodies to clustered AChRs, in a live cell-based assay, were negative in all five patients, suggesting that results from the RIAs were false-positives. It is possible that the AChR antibodies detected by RIA in these cases were non-pathogenic, and directed to intracellular epitopes of the AChR.

miR-30e-5p as predictor of generalization in ocular myasthenia gravis.

Objective: To determine a predictive factor for the risk of conversion from ocular myasthenia gravis (OMG) to generalized MG (GMG) in a prospective study. Methods: RNA was isolated from serum samples and detection of microRNA (miRNA) expression analyzed with qPCR. In the discovery set, 179 human miRNAs were assayed for profiling of five OMG patients and four age- and gender-matched healthy controls. Based on the specific accumulation pattern of 19 miRNAs from the discovery set, in addition to miRNAs previously found elevated in generalized MG (GMG; miR-150-5p and miR-30e-5p), 21 miRNAs were subsequently analyzed in a validation cohort of 83 OMG patients (82 immunosuppression treatment naive; 49 male) within 3 months of diagnosis and at a follow-up visit (median duration 28 months from first visit). Results: Thirteen patients generalized 14.8 ± 12.0 months after the diagnosis and the majority (85%) belonged to the late onset MG group. Two miRNAs were significantly higher in secondary GMG (SGMG) patients compared to OMG patients with late onset MG: miR-30e-5p (9.1 ± 0.5 vs. 6.3 ± 0.9; P < 0.0001) and miR-150-5p (7.4 ± 1.1 vs. 6.4 ± 1.1; P = 0.01). The sensitivity for miR-30e-5p in differentiating OMG and SGMG was 96% in all OMG patients and 100% in late onset OMG patients. Interpretation: This is the first study to describe a potential predictive factor associated with the risk of generalization for patients with OMG. Raised levels (>8) of miR-30e-5p at initial presentation in patients with ocular MG symptoms, give a predictive cut-off for subsequent generalization of 96-100%.

Circulating microRNA miR-21-5p, miR-150-5p and miR-30e-5p correlate with clinical status in late onset myasthenia gravis.

There are no biomarkers for late onset myasthenia gravis (LOMG; onset >50 years). We evaluated circulating microRNA in a discovery cohort of 4 LOMG patients and 4 healthy controls and in a prospective diagnostic validation cohort of 73 LOMG patients (48 male) with longitudinal follow-up samples. In immunosuppression naïve patients, levels of miRNAs miR-150-5p, miR-21-5p and miR-30e-5p decreased in parallel with clinical improvement after initiation of immunosuppression and their levels positively correlated with the clinical MG composite score. Levels of miR-150-5p and miR-21-5p were lower in patients with ocular compared to generalized LOMG. Circulating miR-150-5p, miR-21-5p and miR-30e-5p correlate with the clinical course in LOMG.