Correlation between myasthenia gravis-activities of daily living (MG-ADL) and quantitative myasthenia gravis (QMG) assessments of anti-acetylcholine receptor antibody-positive refractory generalized myasthenia gravis in the phase 3 regain study

Identification of disease phenotypes in acetylcholine receptor-antibody myasthenia gravis using proteomics-based consensus clustering

BACKGROUND

The clinical heterogeneity of myasthenia gravis (MG), an autoimmune disease defined by antibodies (Ab) directed against the postsynaptic membrane, constitutes a challenge for patient stratification and treatment decision making. Novel strategies are needed to classify patients based on their biological phenotypes aiming to improve patient selection and treatment outcomes.

METHODS

For this purpose, we assessed the serum proteome of a cohort of 140 patients with anti-acetylcholine receptor-Ab-positive MG and utilised consensus clustering as an unsupervised tool to assign patients to biological profiles. For in-depth analysis, we used immunogenomic sequencing to study the B cell repertoire of a subgroup of patients and an in vitro assay using primary human muscle cells to interrogate serum-induced complement formation.

FINDINGS

This strategy identified four distinct patient phenotypes based on their proteomic patterns in their serum. Notably, one patient phenotype, here named PS3, was characterised by high disease severity and complement activation as defining features. Assessing a subgroup of patients, hyperexpanded antibody clones were present in the B cell repertoire of the PS3 group and effectively activated complement as compared to other patients. In line with their disease phenotype, PS3 patients were more likely to benefit from complement-inhibiting therapies. These findings were validated in a prospective cohort of 18 patients using a cell-based assay.

INTERPRETATION

Collectively, this study suggests proteomics-based clustering as a gateway to assign patients to a biological signature likely to benefit from complement inhibition and provides a stratification strategy for clinical practice.

FUNDING

CN and CBS were supported by the Forschungskommission of the Medical Faculty of the Heinrich Heine University Düsseldorf. CN was supported by the Else Kröner-Fresenius-Stiftung (EKEA.38). CBS was supported by the Deutsche Forschungsgemeinschaft (DFG-German Research Foundation) with a Walter Benjamin fellowship (project 539363086). The project was supported by the Ministry of Culture and Science of North Rhine-Westphalia (MODS, "Profilbildung 2020" [grant no. PROFILNRW-2020-107-A]).

Translation and validation of the Myasthenia Gravis Activities of Daily Living Questionnaire: Latvian version

Introduction

Our aim was to translate, adapt and validate the Myasthenia Gravis Activities of Daily Living scale into the Latvian language and to evaluate this instrument (MG-ADL-L) in terms of construct validity and reliability.

Methods

We enrolled patients with a confirmed MG diagnosis, who could speak Latvian fluently. We performed translation and adaptation according to the cross-cultural adaptation guidelines for self-reported measures. The patients were evaluated by a physician according to the Myasthenia Gravis Foundation of America classification (MGFA) and using the Myasthenia Gravis Composite Score (MGCS). Patients were asked to complete the MG-ADL-L and the 15-item Myasthenia Gravis Quality of Life (MGQOL15) Internal consistency was evaluated based on Cronbach's α, reproducibility-Cohen's weighted kappa and construct validity-Spearman's correlation between the MG-ADL-L and the MGQOL15 and MGCS. We used the Kruskal-Wallis H test to compare the MG-ADL-L score distribution between the MGFA groups.

Results

38 enrolled patients in the study. There was an acceptable internal consistency (Cronbach's α = 0.76) and moderate to very good agreement between the test and retest scores (Cohen's weighted kappa = 0.54 and 0.81). The MG-ADL-L showed a moderate positive correlation with the MGQOL15 (r = 0.5, p = 0.001) and the MGCS (r = 0.62, p < 0.001). There was a significant difference in MG-ADL-L scores between the MGFA groups (p = 0.007).

Discussion

The MG-ADL-L is a valid and reliable self-reported scale to assess and evaluate symptom severity and the impact of the disease on the lives of patients with MG.

Patient-Reported Symptom Severity in a Nationwide Myasthenia Gravis Cohort: Cross-sectional Analysis of the Swedish GEMG Study

BACKGROUND AND OBJECTIVES

To describe myasthenia gravis activities of daily living (MG-ADL) in relation to clinical characteristics in a large Swedish nationwide cohort.

METHODS

In a cross-sectional prevalence cohort study, the Genes and Environment in Myasthenia Gravis study, performed from November 2018 through August 2019, patients with myasthenia gravis (MG) were invited to submit an extensive 106-item life environment questionnaire, including the MG-ADL score. Patients were classified into early-onset MG (EOMG, <50 years), late-onset MG (LOMG, ≥50 years), or thymoma-associated MG (TAMG). Comparisons of disease-specific characteristics were made between subgroups, sexes, and different MG-ADL scores.

RESULTS

A total of 1,077 patients were included, yielding a 74% response rate: 505 (47%) were classified as EOMG, 520 (48%) LOMG, and 45 (4%) TAMG. Mean age at inclusion was 64.3 years (SD 15.7) and mean disease duration was 14.6 years (SD 14.0). Complete MG-ADL scores (n = 1,035) ranged from 0p to 18p, where 26% reported a score of 0p. Higher MG-ADL scores were associated with female sex, obesity, and diagnostic delay (odds ratio [OR] 1.62, 1.72, and 1.69; p adj = 0.017, 0.013, and 0.008) and inversely correlated with high educational attainment (OR 0.59; p adj = 0.02), but not with age at inclusion, disease subtype, or disease duration. Almost half of the population (47%) reported MG-ADL ≥3p, corresponding to an unsatisfactory symptom state.

DISCUSSION

In this nationwide study, comprising more than 40% of the prevalent MG population in Sweden, almost half of the patients reported current disease symptoms associated with an unsatisfactory symptom state, indicating the need for improved treatment options.

Consistent improvement with eculizumab across muscle groups in myasthenia gravis

OBJECTIVE

To assess whether eculizumab, a terminal complement inhibitor, improves patient- and physician-reported outcomes (evaluated using the myasthenia gravis activities of daily living profile and the quantitative myasthenia gravis scale, respectively) in patients with refractory anti-acetylcholine receptor antibody-positive generalized myasthenia gravis across four domains, representing ocular, bulbar, respiratory, and limb/gross motor muscle groups.

METHODS

Patients with refractory anti-acetylcholine receptor antibody-positive generalized myasthenia gravis were randomized 1:1 to receive either placebo or eculizumab during the REGAIN study (NCT01997229). Patients who completed REGAIN were eligible to continue into the open-label extension trial (NCT02301624) for up to 4 years. The four domain scores of each of the myasthenia gravis activities of daily living profile and the quantitative myasthenia gravis scale recorded throughout REGAIN and through 130 weeks of the open-label extension were analyzed.

RESULTS

Of the 125 patients who participated in REGAIN, 117 enrolled in the open-label extension; 61 had received placebo and 56 had received eculizumab during REGAIN. Patients experienced rapid improvements in total scores and all four domain scores of both the myasthenia gravis activities of daily living profile and the quantitative myasthenia gravis scale with eculizumab treatment. These improvements were sustained through 130 weeks of the open-label extension.

INTERPRETATION

Eculizumab treatment elicits rapid and sustained improvements in muscle strength across ocular, bulbar, respiratory, and limb/gross motor muscle groups and in associated daily activities in patients with refractory anti-acetylcholine receptor antibody-positive generalized myasthenia gravis.

Correlation of Quantitative Myasthenia Gravis and Myasthenia Gravis Activities of Daily Living scales in the MGTX study

Introduction

Quantitative Myasthenia Gravis (QMG) and Myasthenia Gravis Activities of Daily Living (MG‐ADL) scales were compared using the data from the Thymectomy Trial in Non‐Thymomatous Myasthenia Gravis Patients Receiving Prednisone Therapy (MGTX) study.

Methods

Correlation between QMG and MG‐ADL raw and change‐from‐baseline scores was calculated every 3 months for 60 months based on treatment groups and minimal manifestation status (MMS).

Results

QMG and MG‐ADL change‐from‐baseline scores correlated significantly, with increasing strength of correlation over time, in both treatment groups. QMG and MG‐ADL raw scores correlated significantly in both treatment groups, with increasing correlation only in the prednisone‐alone group. Correlation between raw scores was weaker in patients who were in MMS, demonstrating a “floor effect” on the MG‐ADL scale. Raw QMG scores could be modeled assuming a normal distribution, whereas raw MG‐ADL scores could not be modeled this way.

Discussion

The floor effect and skewed distribution of the MG‐ADL measure should be taken into account in the design of myasthenia gravis clinical trials.

'Minimal symptom expression' in patients with acetylcholine receptor antibody-positive refractory generalized myasthenia gravis treated with eculizumab

Background

The efficacy and tolerability of eculizumab were assessed in REGAIN, a 26-week, phase 3, randomized, double-blind, placebo-controlled study in anti-acetylcholine receptor antibody-positive (AChR+) refractory generalized myasthenia gravis (gMG), and its open-label extension.

Methods

Attainment of ‘minimal symptom expression’ was evaluated using patient-reported outcome measures of gMG symptoms [MG activities of daily living scale (MG-ADL), 15-item MG quality of life questionnaire (MG-QOL15)] at the completion of REGAIN and during the open-label extension. ‘Minimal symptom expression’ was defined as MG-ADL total score of 0–1 or MG-QOL15 total score of 0–3.

Results

At REGAIN week 26, more eculizumab-treated patients achieved ‘minimal symptom expression’ versus placebo [MG-ADL: 21.4% vs 1.7%; difference 19.8%; 95% confidence interval (CI) 8.5, 31.0; p = 0.0007; MG-QOL15: 16.1% vs 1.7%; difference 14.4%; 95% CI 4.3, 24.6; p = 0.0069]. During the open-label extension, the proportion of patients in the placebo/eculizumab group who achieved ‘minimal symptom expression’ increased after initiating eculizumab treatment and was sustained through 130 weeks of open-label eculizumab (MG-ADL: 1.7 to 27.8%; MG-QOL15: 1.7 to 19.4%). At extension study week 130, similar proportions of patients in the eculizumab/eculizumab and placebo/eculizumab groups achieved ‘minimal symptom expression’ (MG-ADL: 22.9% and 27.8%, respectively, p = 0.7861; MG-QOL15: 14.3% and 19.4%, respectively, p = 0.7531). The long-term tolerability of eculizumab was consistent with previous reports.

Conclusions

Patients with AChR+ refractory gMG who receive eculizumab can achieve sustained ‘minimal symptom expression’ based on patient-reported outcomes. ‘Minimal symptom expression’ may be a useful tool in measuring therapy effectiveness in gMG.

Trial registration

ClinicalTrials.gov NCT01997229, NCT02301624.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-09770-y) contains supplementary material, which is available to authorized users.

Understanding the burden of refractory myasthenia gravis

Myasthenia gravis (MG) is an autoantibody-mediated disease that compromises the acetylcholine receptors or associated structures of the postsynaptic membrane of the neuromuscular junction. This leads to impaired neuromuscular transmission and subsequent fluctuating fatigability and weakness of ocular, bulbar, and limb skeletal muscles. Over the past few decades, there have been significant advances in our understanding of the disease pathophysiology and improvements in prognosis due to intensive care medicine and immunomodulation. Despite this, an estimated 10-20% of patients with MG do not achieve an adequate response, are intolerant to conventional treatment, or require chronic treatment with intravenous immunoglobulins or plasma separation procedures. Such patients are regarded as having MG that is 'refractory' to treatment and may represent a distinct clinical subgroup. Because the majority of patients with MG have well-controlled disease, the burden of illness in the minority with refractory disease is poorly understood and may be underestimated. However, clinically these patients are liable to experience extreme fatigue, considerable disability owing to uncontrolled symptoms, and frequent myasthenic crises and hospitalizations. Both acute adverse effects and an increased risk of comorbidity from treatment regimens may contribute to reduced quality of life. As yet, little is known concerning the impact of refractory MG on mental health and health-related quality of life. This review aims to highlight the burden of disease and unmet needs in patients with refractory MG.