Pre-thymectomy disease severity predicts outcome in acetylcholine receptor antibody-positive generalised myasthenia gravis.

INTRODUCTION: There are only a few studies exploring post-thymectomy outcome in patients with acetylcholine receptor antibody (AChR-Ab)-positive generalised myasthenia gravis (MG). OBJECTIVE: To assess the predictors of outcome in patients with AChR-Ab-positive generalised MG who underwent thymectomy. METHODS: A retrospective study of 53 patients from a single neuroscience centre in the UK. RESULTS: The mean disease duration from diagnosis was 6.2 ± 4.3 years. Pre-thymectomy, 37 patients had mild weakness affecting muscles other than ocular muscles, 11 patients had moderate weakness and 5 patients had severe weakness. 27/53 patients had thymoma. Post-thymectomy (mean duration of 5.7 ± 4.2 years), 34 patients (64%) had a good outcome characterised by Myasthenia Gravis Foundation of America Post-Intervention Status of complete stable remission (no symptoms or signs of MG for at least 1 year without any therapy) or pharmacological remission (no symptoms or signs of MG with some form of therapy) or minimal manifestations (no symptoms of functional limitations from MG but weakness on examination of some muscles with or without some form of therapy) on last follow-up visit. Having thymomatous or non-thymomatous MG did not predict the outcome. The only variable that did predict outcome was pre-thymectomy disease severity; patients with mild weakness before thymectomy had a favourable outcome. We found an accuracy of 83% predicting outcome (95% confidence interval (CI) 60%, 100%) with a sensitivity of 84% (95% CI 68%, 94%) and specificity of 81% (95% CI 54%, 96%). CONCLUSION: Disease severity before thymectomy predicts outcome in patients with AChR-Ab-positive generalised 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.

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%.