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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])., Competing Interests: Declaration of interests CN, CBS, SGM and TR have been granted a patent by the European Patent Office (EPO) relating to the use of ITIH3 as a biomarker for (assessing) disease activity in myasthenia gravis patients (EP22195296.3). CN received honoraria for lectures from Alexion, ArgenX and UCB Pharma. CBS received honoraria for lectures from Merc and travel expenses from Alexion. FS received travel support, honoraria for lectures and adboards from Alexion, ArgenX and UCB Pharma. LM received honoraria for lectures from ArgenX and travel support from Alexion. NH received honoraria for lectures and travel support from Alexion, ArgenX and Merck. MP received consulting fees, honoraria for lectures and adboards from Alexion and ArgenX. SR received honoraria for adboards and travel support from Alexion, Bristol Myers Squibb and Merck. FK received travel support from Alexion, Merck and Novartis. TS received grants from Alnylam Pharmaceuticals, CSL Behring, Novartis, Siemens; TS received consulting fees, honoraria for lectures and adboards from Alexion, Alnylam Pharmaceuticals, argenx, Bayer Vital, Biogen, Bristol Myers Squibb, Celgene, Centogene, CSL Behring, Euroimmun, Grifols, Hexal AG, Horizon, Janssen-Cilag, Merck Serono, Novartis, Pfizer, Roche, Sanofi, Siemens, Swedish Orphan Biovitrum, Teva, Viatris. AM received consulting fees from Alexion (AstraZeneca Rare Disease), Argenx, Janssen Pharmaceuticals, Merck, Octapharma, Union Chimique Belge (UCB), Xcenda; AM received honoraria for lectures and adboards from Alexion, Argenx, Desitin, Dierks, Grifols, Hormosan, Novartis, Sanofi. SGM received honoraria for lectures and travel support from Academy 2, Argenx, Alexion, Almirall, Amicus Therapeutics Germany, Bayer Health Care, Biogen, BioNtech, BMS, Celgene, Datamed, Demecan, Desitin, Diamed, Diaplan, DIU Dresden, DPmed, Gen Medicine and Healthcare products, Genzyme, Hexal AG, IGES, Impulze GmbH, Janssen Cilag, KW Medipoint, MedDay Pharmaceuticals, Merck Serono, MICE, Mylan, Neuraxpharm, Neuropoint, Novartis, Novo Nordisk, ONO Pharma, Oxford PharmaGenesis, QuintilesIMS, Roche, Sanofi-Aventis, Springer Medizin Verlag, STADA, Chugai Pharma, Teva, UCB, Viatris, Wings for Life international and Xcenda. TR received honoraria for lectures, adboards and travel support from Alexion, Argenx, Biogen, Celgene, BMS, Genzyme, Merck Serono, Novartis, Novartis, Roche, Sanofi-Aventis and Teva. All other authors declare that they have no competing interests., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Myasthenia gravis is a well-understood autoimmune disease of the neuromuscular synapse that is medicinally treatable with favorable results and therefore should not be overlooked in the differential diagnostic evaluation of vertical diplopia. Myasthenia is primarily a clinical diagnosis. Positive indications include double vision of fluctuating severity, diurnal variations, double vision after lengthy gaze fixation on a distant object and in the primary position as well as diplopia in various visual directions, often associated with a varying extent of ptosis. Clinical tests are the Simpson test, the ice on eyes test and the probatory administration of pyridostigmine. Positive results corroborate this diagnosis but negative results do not exclude myasthenia. The same applies for the determination of specific autoantibodies. In addition to ocular symptoms it is important to search for generalized symptoms and bulbopharyngeal symptoms in particular should prompt immediate neurological diagnostics. In addition to symptomatic treatment a wide range of immunotherapeutic agents are available. Thymectomy is also used for immunomodulatory indications according to the 2023 revised guidelines. Patient-centered treatment goals, patient education and comprehensive information, also via the self-help organization German Myasthenia Society, are essential components of successful treatment of myasthenia., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Myasthenia gravis is a chronic antibody-mediated autoimmune disease disrupting neuromuscular synaptic transmission. Informative biomarkers remain an unmet need to stratify patients with active disease requiring intensified monitoring and therapy; their identification is the primary objective of this study. We applied mass spectrometry-based proteomic serum profiling for biomarker discovery. We studied an exploration and a prospective validation cohort consisting of 114 and 140 anti-acetylcholine receptor antibody (AChR-Ab)-positive myasthenia gravis patients, respectively. For downstream analysis, we applied a machine learning approach. Protein expression levels were confirmed by ELISA and compared to other myasthenic cohorts, in addition to myositis and neuropathy patients. Anti-AChR-Ab levels were determined by a radio receptor assay. Immunohistochemistry and immunofluorescence of intercostal muscle biopsies were employed for validation in addition to interactome studies of inter-alpha-trypsin inhibitor heavy chain H3 (ITIH3). Machine learning identified ITIH3 as potential serum biomarker reflective of disease activity. Serum levels correlated with disease activity scores in the exploration and validation cohort and were confirmed by ELISA. Lack of correlation between anti-AChR-Ab levels and clinical scores underlined the need for biomarkers. In a subgroup analysis, ITIH3 was indicative of treatment responses. Immunostaining of muscle specimens from these patients demonstrated ITIH3 localization at the neuromuscular endplates in myasthenia gravis but not in controls, thus providing a structural equivalent for our serological findings. Immunoprecipitation of ITIH3 and subsequent proteomics lead to identification of its interaction partners playing crucial roles in neuromuscular transmission. This study provides data on ITIH3 as a potential pathophysiological-relevant biomarker of disease activity in myasthenia gravis. Future studies are required to facilitate translation into clinical practice., (© 2024. The Author(s).)

Objective: Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy but come with immune-related adverse events (irAEs) that provide a novel challenge for treating physicians. Neuromuscular irAEs, including myositis, myasthenia gravis (MG), and demyelinating polyradiculoneuropathy, lead to significant morbidity and mortality., Methods: We present a case of severe myasthenia-myositis-myocarditis overlap in a patient receiving ICIs for breast cancer. Clinical findings were recorded., Results: A 47-year-old woman developed tetraparesis, dysphagia, and muscle pain during ICI treatment. MG with a thymoma had been diagnosed earlier. Neuromuscular overlap irAEs with cardiac affection was confirmed, and ICI treatment was discontinued. Given a lack of clinical response to standard therapies, a muscle biopsy was performed demonstrating complement deposition. Eculizumab treatment led to rapid improvement in muscle strength and cardiac function., Discussion: Neuromuscular irAEs are associated with a high in-hospital mortality, and specific treatment strategies remain an unmet need. Here, early muscle biopsy enabled targeted therapy after standard approaches failed, thereby highlighting the value of identifying a specific treatment target. To improve therapeutic outcomes, the development of patient-tailored strategies for neuromuscular irAEs requires further studies., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Inflammatory neuromuscular disorders encompass a diverse group of immune-mediated diseases with varying clinical manifestations and treatment responses. The identification of specific biomarkers has the potential to provide valuable insights into disease pathogenesis, aid in accurate diagnosis, predict disease course, and monitor treatment efficacy. However, the rarity and heterogeneity of these disorders pose significant challenges in the identification and implementation of reliable biomarkers. Here, we aim to provide a comprehensive review of biomarkers currently established in Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), myasthenia gravis (MG), and idiopathic inflammatory myopathy (IIM). It highlights the existing biomarkers in these disorders, including diagnostic, prognostic, predictive and monitoring biomarkers, while emphasizing the unmet need for additional specific biomarkers. The limitations and challenges associated with the current biomarkers are discussed, and the potential implications for disease management and personalized treatment strategies are explored. Collectively, biomarkers have the potential to improve the management of inflammatory neuromuscular disorders. However, novel strategies and further research are needed to establish clinically meaningful biomarkers.

Therapeutic strategies targeting complement have revolutionized the treatment of myasthenia gravis (MG). However, a deeper understanding of complement modulation in the human system is required to improve treatment responses and identify off-target effects shaping long-term outcomes. For this reason, we studied a cohort of patients with MG treated with either eculizumab or azathioprine as well as treatment-naive patients using a combined proteomics and metabolomics approach. This strategy validated known effects of eculizumab on the terminal complement cascade. Beyond that, eculizumab modulated the serum proteometabolome as distinct pathways were altered in eculizumab-treated patients, including the oxidative stress response, mitogen-activated protein kinase signaling, and lipid metabolism with particular emphasis on arachidonic acid signaling. We detected reduced levels of arachidonate 5-lipoxygenase (ALOX5) and leukotriene A4 in eculizumab-treated patients. Mechanistically, ligation of the C5a receptor (C5aR) is needed for ALOX5 metabolism and generation of downstream leukotrienes. As eculizumab prevents cleavage of C5 into C5a, decreased engagement of C5aR may inhibit ALOX5-mediated synthesis of pro-inflammatory leukotrienes. These findings indicate distinct off-target effects induced by eculizumab, illuminating potential mechanisms of action that may be harnessed to improve treatment outcomes.

Objective: Myasthenia gravis (MG) is the most common autoimmune disorder affecting the neuromuscular junction. However, evidence shaping treatment decisions, particularly for treatment-refractory cases, is sparse. Both rituximab and eculizumab may be considered as therapeutic options for refractory MG after insufficient symptom control by standard immunosuppressive therapies., Methods: In this retrospective observational study, we included 57 rituximab-treated and 20 eculizumab-treated patients with MG to compare the efficacy of treatment agents in generalised, therapy-refractory anti-acetylcholine receptor antibody (anti-AChR-ab)-mediated MG with an observation period of 24 months. Change in the quantitative myasthenia gravis (QMG) score was defined as the primary outcome parameter. Differences between groups were determined in an optimal full propensity score matching model., Results: Both groups were comparable in terms of clinical and demographic characteristics. Eculizumab was associated with a better outcome compared with rituximab, as measured by the change of the QMG score at 12 and 24 months of treatment. Minimal manifestation of disease was more frequently achieved in eculizumab-treated patients than rituximab-treated patients at 12 and 24 months after baseline. However, the risk of myasthenic crisis (MC) was not ameliorated in either group., Interpretation: This retrospective, observational study provides the first real-world evidence supporting the use of eculizumab for the treatment of refractory, anti-AChR-ab positive MG. Nonetheless, the risk of MC remained high and prompts the need for intensified monitoring and further research effort aimed at this vulnerable patient cohort., Competing Interests: Competing interests: CN reports no conflicts of interest. CBS reports no conflicts of interest. FS received speaking honoraria from Biogen and Alexion. MP received speaker honoraria and travel/accommodation/meeting expenses from Novartis. LR-N reports no disclosures. NM reports no conflicts of interest. PM is on the Advisory Board of HealthNextGen and has equity interest in the company. His research is funded by the Bundesministerium für Bildung und Forschung (BMBF), the European Union, the Else Kröner-Fresenius Stiftung, the Volkswagen Stiftung and the Einstein Foundation Berlin. AG reports no conflicts of interest. HS reports no conflicts of interest. MS reports no conflicts of interest. BB received travel grants and/or training expenses from Bayer Vital GmbH, IpsenPharma GmbH, Norvartis, Biogen GmbH and Genzyme, as well as lecture fees from Ipsen Pharma GmbH, Alexion Pharma GmbH, Merck, Sanofi Genzyme and Roche. AT reports on conflicts of interest. TH received speaker honoraria and advisor honoraria from Alexion, Argenx, Biogen, Roche, Sanofi-Genzyme, Novartis and Hormosan. SS reports no conflicts of interest. SV reports no conflicts of interest. AM received speaker honoraria, consulting services and/or research support research from Alexion, argnx, GRIFOLS, Hormosan, Janssen, Octapharma, UCB and Vitaccess. He serves as chairman of the medical advisory board of the German Myasthenia Gravis Society. HW receives honoraria for acting as a member of Scientific Advisory Boards, Biogen, Evgen, Genzyme, MedDay Pharmaceuticals, Merck Serono, Novartis, Roche Pharma AG and Sanofi-Aventis as well as speaker honoraria and travel support from Alexion, Biogen, Cognomed, F. Hoffmann-La Roche, Gemeinnützige Hertie-Stiftung, Merck Serono, Novartis, Roche Pharma AG, Genzyme, TEVA and WebMD Global. HW is acting as a paid consultant for AbbVie, Actelion, Biogen, IGES, Johnson & Johnson, Novartis, Roche, Sanofi-Aventis and the Swiss Multiple Sclerosis Society. His research is funded by the German Ministry for Education and Research (BMBF), Deutsche Forschungsgemeinschaft (DFG), Else Kröner Fresenius Foundation, Fresenius Foundation, the European Union, Hertie Foundation, NRW Ministry of Education and Research, Interdisciplinary Center for Clinical Studies (IZKF) Muenster and RE Children’s Foundation, Biogen, GlaxoSmithKline GmbH, Roche Pharma AG, Sanofi-Genzyme. SGM receives honoraria for lecturing, and travel expenses for attending meetings from Almirall, Amicus Therapeutics Germany, Bayer Health Care, Biogen, Celgene, Diamed, Genzyme, MedDay Pharmaceuticals, Merck Serono, Novartis, Novo Nordisk, ONO Pharma, Roche, Sanofi-Aventis, Chugai Pharma, QuintilesIMS and Teva. His research is funded by the German Ministry for Education and Research (BMBF), Bundesinstitut für Risikobewertung (BfR), Deutsche Forschungsgemeinschaft (DFG), Deutsche Multiple Sklerose Gesellschaft (DMSG), Else Kröner Fresenius Foundation, Gemeinsamer Bundesausschuss (G-BA), German Academic Exchange Service, Hertie Foundation, Interdisciplinary Center for Clinical Studies (IZKF) Muenster, German Foundation Neurology and Alexion, Almirall, Amicus Therapeutics Germany, Biogen, Diamed, Fresenius Medical Care, Genzyme, HERZ Burgdorf, Merck Serono, Novartis, ONO Pharma, Roche and Teva. HW receives honoraria for acting as a member of Scientific Advisory Boards, Biogen, Evgen, Genzyme, MedDay Pharmaceuticals, Merck Serono, Novartis, Roche Pharma AG and Sanofi-Aventis as well as speaker honoraria and travel support from Alexion, Biogen, Cognomed, F. Hoffmann-La Roche, Gemeinnützige Hertie-Stiftung, Merck Serono, Novartis, Roche Pharma AG, Genzyme, TEVA and WebMD Global. TR reports grants from German Ministry of Education, Science, Research and Technology, grants and personal fees from Sanofi-Genzyme and Alexion; personal fees from Biogen, Roche and Teva; personal fees and non-financial support from Merck Serono, outside the submitted work., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Myasthenic crisis (MC) and disease exacerbation in myasthenia gravis (MG) are associated with significant lethality and continue to impose a high disease burden on affected patients. Therefore, we sought to determine potential predictors for MC and exacerbation as well as to identify factors affecting outcome., Methods: We examined a retrospective, observational cohort study of patients diagnosed with MG between 2000 and 2021 with a mean follow-up of 62.6 months after diagnosis from eight tertiary hospitals in Germany. A multivariate Cox regression model with follow-up duration as the time variable was used to determine independent risk factors for MC and disease exacerbation., Results: 815 patients diagnosed with MG according to national guidelines were included. Disease severity at diagnosis (quantitative MG score or Myasthenia Gravis Foundation of America class), the presence of thymoma and anti-muscle specific tyrosine kinase-antibodies were independent predictors of MC or disease exacerbation. Patients with minimal manifestation status 12 months after diagnosis had a lower risk of MC and disease exacerbation than those without. The timespan between diagnosis and the start of immunosuppressive therapy did not affect risk. Patients with a worse outcome of MC were older, had higher MGFA class before MC and at admission, and had lower vital capacity before and at admission. The number of comorbidities, requirement for intubation, prolonged mechanical ventilation, and MC triggered by infection were associated with worse outcome. No differences between outcomes were observed comparing treatments with IVIG (intravenous immunoglobulin) vs. plasma exchange vs. IVIG together with plasma exchange., Conclusions: MC and disease exacerbations inflict a substantial burden of disease on MG patients. Disease severity at diagnosis and antibody status predicted the occurrence of MC and disease exacerbation. Intensified monitoring with emphasis on the prevention of infectious complications could be of value to prevent uncontrolled disease in MG patients., (© 2022. The Author(s).)

Myasthenia gravis (MG) is a prototypical autoimmune disease of the neuromuscular junction (NMJ). The study of the underlying pathophysiology has provided novel insights into the interplay of autoantibodies and complement-mediated tissue damage. Experimental autoimmune myasthenia gravis (EAMG) emerged as a valuable animal model, designed to gain further insight and to test novel therapeutic approaches for MG. However, the availability of native acetylcholine receptor (AChR) protein is limited favouring the use of recombinant proteins. To provide a simplified platform for the study of MG, we established a model of EAMG using a recombinant protein containing the immunogenic sequence of AChR in mice. This model recapitulates key features of EAMG, including fatigable muscle weakness, the presence of anti-AChR-antibodies, and engagement of the NMJ by complement and a reduced NMJ density. Further characterization of this model demonstrated a prominent B cell immunopathology supported by T follicular helper cells. Taken together, the herein-presented EAMG model may be a valuable tool for the study of MG pathophysiology and the pre-clinical testing of therapeutic applications. [ABSTRACT FROM AUTHOR]