Efgartigimod in generalized myasthenia gravis: A real-life experience at a national reference center.

BACKGROUND AND PURPOSE: Inhibition of the neonatal Fc receptor (FcRn) for IgG is a promising new therapeutic strategy for antibody-mediated disorders. We report our real-life experience with efgartigimod (EFG) in 19 patients with generalized myasthenia gravis (gMG) along a clinical follow-up of 14 months. METHODS: EFG was administered according to the GENERATIVE protocol (consisting of a Fixed period of two treatment cycles [given 1 month apart] of four infusions at weekly intervals, followed by a Flexible period of re-cycling in case of worsening). Eight patients were positive for acetylcholine receptor antibody, four for muscle-specific tyrosine kinase antibody, and two for lipoprotein-related protein 4 antibody, and five were classified as triple negative. Efficacy of EFG was assessed by the Myasthenia Gravis Activities of Daily Living, Myasthenia Gravis Composite, and Quantitative Myasthenia Gravis scales. RESULTS: Fifty-three percent of patients needed three treatment cycles, 26% needed four, and 21% needed five along the 14-month clinical follow-up. Meaningful improvement was observed at the end of each cycle with the clinical scores adopted. EFG had a dramatic effect on disease course, as during the year before treatment eight of 19 patients (42%) were hospitalized, and 15 of 19 (79%) needed treatment with plasma exchange or immunoglobulins; three of 19 (16%) were admitted to the intensive care unit. During EFG, none of the patients was hospitalized and only one patient required plasma exchange and intravenous immunoglobulins. No major side effects or infusion-related reactions occurred. CONCLUSIONS: We observed that EFG was safe and modified significantly the course of the disease along a 14-month follow-up. Our experience strengthens the role of FcRn inhibition as an effective new tool for long-term treatment of gMG.

Current drug treatment of myasthenia gravis.

PURPOSE OF REVIEW: Myasthenia Gravis (MG) is a rare neurological disorder affecting the neuromuscular junction. Clinical hallmarks are fatigability and weakness affecting the extraocular, axial, limb and/or respiratory muscles. Despite immunosuppressive treatment, mainly based on corticosteroids and nonsteroidal immunosuppressants, the burden of MG is still significant, both in terms of inadequate disease control and burdensome side effects. Driven by such limits, the past years have been characterized by an escalation of MG drug development, with novel molecules which now focuses on having a more targeted effect, with a higher safety and efficacy profile. RECENT FINDINGS: As the pathogenic mechanism of MG are slowly being unravelled, new potential targets for treatments are being considered. This has led since 2017 to the Food and Drug Administration (FDA)-approval of three new drugs that either act by blocking the complement system (i.e., eculizumab and ravulizumab) or by blocking the neonatal Fc receptor thus preventing immunoglobulin recycling and reducing imunoglobulin G (IgG) antibodies (i.e., efgartigimod). Other drugs, with similar mechanism of action, are currently under review for approval. SUMMARY: The repertoire of available and developmental therapies for MG is rapidly expanding, finally responding to the unmet need of a more targeted and effective therapeutic approach in MG.

Comparison of quantitative muscle ultrasound and whole-body muscle MRI in facioscapulohumeral muscular dystrophy type 1 patients.

INTRODUCTION: Muscle ultrasound is a fast, non-invasive and cost-effective examination that can identify structural muscular changes by assessing muscle thickness and echointensity (EI) with a quantitative analysis (QMUS). To assess applicability and repeatability of QMUS, we evaluated patients with genetically confirmed facioscapulohumeral muscular dystrophy type 1 (FSHD1), comparing their muscle ultrasound characteristics with healthy controls and with those detected by MRI. We also evaluated relationships between QMUS and demographic and clinical characteristics. MATERIALS AND METHODS: Thirteen patients were included in the study. Clinical assessment included MRC sum score, FSHD score and The Comprehensive Clinical Evaluation Form (CCEF). QMUS was performed with a linear transducer scanning bilaterally pectoralis major, deltoid, rectus femoris, tibialis anterior and semimembranosus muscles in patients and healthy subjects. For each muscle, we acquired three images, which were analysed calculating muscle EI by computer-assisted grey-scale analysis. QMUS analysis was compared with semiquantitative 1.5 T muscle MRI scale. RESULTS: All muscles in FSHD patients showed a significant increased echogenicity compared to the homologous muscles in healthy subjects. Older subjects and patients with higher FSHD score presented increased muscle EI. Tibialis anterior MRC showed a significant inverse correlation with EI. Higher median EI was found in muscles with more severe MRI fat replacement. CONCLUSIONS: QMUS allows quantitative evaluation of muscle echogenicity, displaying a tight correlation with muscular alterations, clinical and MRI data. Although a confirmation on larger sample is needed, our research suggests a possible future application of QMUS in diagnosis and management of muscular disorders.

Concordance between patient- and physician-reported Myasthenia Gravis Activities of Daily Living (MG-ADL) scores.

INTRODUCTION/AIMS: Myasthenia gravis (MG) is a neuromuscular disease characterized by abnormal skeletal muscle fatiguability. The MG Activities of Daily Living (MG-ADL) scale assesses eight symptoms and is often used as primary endpoint in MG clinical trials where it is completed by neurologists. However, in observational studies, patients frequently complete the MG-ADL scale independently of their neurologist. In this study we aimed to assess the concordance between self- and physician-reported MG-ADL scores. METHODS: An international observational study was conducted among adult patients with MG scheduled for a routine visit or who entered the hospital via emergency services. Consenting patients and physicians completed the MG-ADL. Concordance between assessments was calculated using Gwet's agreement coefficient (Gwet's AC) for the MG-ADL individual items and the intraclass correlation coefficient (ICC) for the MG-ADL total score. RESULTS: Data were collected from 137 patients (63% female; mean age, 57.7 years). Physicians assessed the patient's symptoms as slightly more severe (8.1 vs 7.5 MG-ADL total score, respectively), corresponding to a difference of 0.6 on a range from 0 to 24. The ICC for the MG-ADL total score between the patient and the physician assessment was 0.94 (95% confidence interval, 0.89 to 0.95), showing excellent concordance. Gwet's AC showed substantial to almost perfect agreement for all items, except eyelid droop, for which the agreement was moderate. DISCUSSION: Our results demonstrate that patients and neurologists have a concordant assessment of the patient's MG symptoms when using the MG-ADL scale. This evidence supports patient self-administration of the MG-ADL in clinical practice and research.

Ravulizumab for the treatment of myasthenia gravis.

INTRODUCTION: Myasthenia gravis (MG) is a neurological B-cell mediated autoimmune disorder affecting the neuromuscular junction. MG therapeutics have always relied on nonselective immunosuppression with oral steroids and non-steroidal immunosuppressants, mainly with good clinical response. However, clinical stabilization is often reached at the cost of many troublesome side effects and up to 15% of MG patients are deemed as refractory to conventional immunosuppression. This highlights the need of a more targeted and efficacious therapeutic approach. Results from the randomized-controlled period of the CHAMPION study demonstrate a good safety, tolerability, and efficacy profile of ravulizumab compared to placebo. Like eculizumab, ravulizumab is an anti-C5 monoclonal antibody, but with an enhanced pharmacokinetic profile, that allows dosing every 8 weeks. AREAS COVERED: We provide an overview of ravulizumab biological features and results from the phase III CHAMPION MG (NCT03920293) study. EXPERT OPINION: Data of the CHAMPION MG trial demonstrate that ravulizumab is effective and safe in the treatment of generalized MG. Having a rapid clinical effect, with long-term clinical response, ravulizumab could represent a selective immunosuppressive drug of choice in the future therapeutic algorithm of MG, where conventional immunosuppressants slowly leave room for newer drugs with a more targeted mechanism of action.

Muscle MRI in immune-mediated necrotizing myopathy (IMNM): implications for clinical management and treatment strategies.

OBJECTIVES: Immune-mediated necrotizing myopathy (IMNM) is the most severe idiopathic inflammatory myopathy (IIM) and early aggressive poly-immunotherapy is often required to reduce long-term disability. The aim of this study is to investigate muscle MRI in IMNM as outcome measure for disease activity, severity, progression, response to treatment, and to better characterize the pattern of muscle involvement. METHODS: This is a retrospective, observational, cross-sectional, and longitudinal study including 22 IMNM patients, divided into three groups based on timing of first MRI and if performed before or under treatment. T1 score and percentage of STIR positive muscles (STIR%) were considered and analyzed also in relation to demographic, clinical and laboratory characteristics. RESULTS: STIR% was higher in untreated patients and in those who performed MRI earlier (p = 0.001). Pelvic girdle and thighs were in general more affected than legs. T1 score was higher in patients with MRI performed later in disease course (p = 0.004) with a prevalent involvement of the lumbar paraspinal muscles, gluteus medius and minimus, adductor magnus and hamstrings. 22% of STIR positive muscles showed fat replacement progression at second MRI. Higher STIR% at baseline correlated with higher risk of fat replacement at follow-up (p = 0.003); higher T1 score correlated with clinical disability at follow-up, with late treatment start and delayed treatment with IVIG (p = 0.03). INTERPRETATION: Muscle MRI is a sensitive biomarker for monitoring disease activity and therapy response, especially when performed early in disease course and before treatment start, and could represent a supportive outcome measure and early prognostic index in IMNM.

Complement Activation Profile in Myasthenia Gravis Patients: Perspectives for Tailoring Anti-Complement Therapy.

The complement system plays a key role in myasthenia gravis (MG). Anti-complement drugs are emerging as effective therapies to treat anti-acetylcholine receptor (AChR) antibody-positive MG patients, though their usage is still limited by the high costs. Here, we searched for plasma complement proteins as indicators of complement activation status in AChR-MG patients, and potential biomarkers for tailoring anti-complement therapy in MG. Plasma was collected from AChR-MG and MuSK-MG patients, and healthy controls. Multiplex immunoassays and ELISA were used to quantify a panel of complement components (C1Q, C2, C3, C4, C5, Factor B, Factor H, MBL, and properdin) and activation products (C4b, C3b, C5a, and C5b-9), of classical, alternative and lectin pathways. C2 and C5 levels were significantly reduced, and C3, C3b, and C5a increased, in plasma of AChR-MG, but not MuSK-MG, patients compared to controls. This protein profile was indicative of complement activation. We obtained sensitivity and specificity performance results suggesting plasma C2, C3, C3b, and C5 as biomarkers for AChR-MG. Our findings reveal a plasma complement "C2, C3, C5, C3b, and C5a" profile associated with AChR-MG to be further investigated as a biomarker of complement activation status in AChR-MG patients, opening new perspectives for tailoring of anti-complement therapies to improve the disease treatment.

Nerve high-resolution ultrasound in a 2-years follow-up of radial nerve palsy related to humeral shaft fractures.

BACKGROUND: High-resolution nerve ultrasonography (HRUS) could have an emerging importance in diagnosis and follow-up of axonopathic radial palsy associated with humeral shaft fractures due to closed trauma. The aim of our study is to establish the role of HURS in this context through a longitudinal multimodal analysis. METHODS: Clinical, electrodiagnostic (EDX) and HRUS evaluations were prospectively performed at month 1, 3, 6, 12 and 24 from injury, in a continuous series of 19 patients collected in a 5-year study. Clinical severity was scored on MRC of involved muscles, EDX on presence/absence of functional continuity; anatomical continuity and nerve cross sectional area (NCSA) of radial (RN ) and posterior interosseus (PIN) nerves were evaluated through HRUS. RESULTS: All patients showed clinical improvement during follow-up; EDX functional continuity was reached by all patients within 12 months; HRUS revealed RN anatomical continuity in all patients and PIN involvement in 74%. RN NCSA progressively reduced during FU, but it was still significantly higher than contralateral at month 24; PIN NCSA became normal within 24 months. CONCLUSIONS: When anatomical RN continuity is confirmed by HRUS, good functional outcome is reached even in patients with EDX loss of functional continuity. Together with clinical and EDX evaluations, HRUS may provide useful data in the follow-up of radial palsy due to humeral shaft fractures.

Antibody Therapies in Autoimmune Neuromuscular Junction Disorders: Approach to Myasthenic Crisis and Chronic Management.

Myasthenia gravis (MG) is a neurological autoimmune disorder characterized by muscle weakness and fatigue. It is a B cell-mediated disease caused by pathogenic antibodies directed against various components of the neuromuscular junction (NMJ). Despite the wide range of adverse effects, current treatment is still based on non-specific immunosuppression, particularly on long-term steroid usage. The increasing knowledge regarding the pathogenic mechanisms of MG has however allowed to create more target-specific therapies. A very attractive therapeutic approach is currently offered by monoclonal antibodies (mAbs), given their ability to specifically and effectively target different immunopathological pathways, such as the complement cascade, B cell-related cluster of differentiation (CD) proteins, and the human neonatal Fc receptor (FcRn). Up to now, eculizumab, a C5-directed mAb, has been approved for the treatment of generalized MG (gMG) and efgartigimod, a FcRn inhibitor, has just been approved by the U.S. Food and Drug Administration for the treatment of anti-acetylcholine receptor (AChR) antibody positive gMG. Other mAbs are currently under investigation with encouraging preliminary results, further enriching the new range of therapeutic possibilities for MG. This review article provides an overview of the present status of mAb-based therapies for MG, which offer an exciting promise for better outcomes by setting the basis of a precision medicine approach.

Anti-Spike IgG in multiple sclerosis patients after BNT162b2 vaccine: An exploratory case-control study in Italy.

BACKGROUND: Patients with neuroimmunological conditions such as multiple sclerosis (MS) often receive disease-modifying therapies (DMTs) or immunosuppressants which may reduce the response to vaccines. BNT162b2 (Pfizer-BioNTech) is the first COVID-19 vaccine authorized in Italy. Its clinical efficacy and serological response were not evaluated in MS patients receiving DMTs or immunosuppressants. This early multicenter study evaluated serological response to BNT162b2 and safety in these patients. METHODS: From February 2021 we enrolled consecutive MS patients, treated with at least one DMT and all healthcare workers (HCWs), having received or being scheduled to receive the first dose of BNT162b2. Blood samples were collected after the second vaccine dose and analyzed to quantitatively detect the presence of anti-Spike antibodies. Serological response was compared to the one from a control population of HCWs, with neither neuroimmunological conditions nor receiving immunosuppressants. Patients receiving treatments associated with a possible reduced response (Under-scrutiny treatment group) were also compared to those undergoing other treatments. Anti-Spike levels were described as median and interquartile range (IQR). Comparisons were performed with Wilcoxon-Mann-Whitney test. Solicited and unsolicited adverse events (AEs) were collected. RESULTS: 39 MS patients and a control population of 273 HCWs were included. One patient, under treatment with ocrelizumab, did not respond to BNT162b2, while all the remaining patients and all controls developed a serological response to the vaccine. Median anti-Spike levels were similar between patients (1471.0 BAU/ml; IQR 779.7 to 2357.0) and controls (1479.0 BAU/ml; IQR 813.1 to 2528.0) (p = 0.53). Patients included in the Under-scrutiny treatments group showed reduced anti-Spike levels (156.4 BAU/ml; IQR 33.4 to 559.1) compared to those receiving other treatments (1582.4 BAU/ml; IQR 1296.5 to 2219.0) (p = 0.001). Solicited AEs were all mild to moderate in severity, generally reported in the first days after vaccination, and resolved in the following days. Two MS patients reported a clinical relapse after the second vaccine dose. CONCLUSION: BNT162b2 induced a serological response in MS patients treated with DMTs similar to controls not receiving DMTs or immunosuppressants. Some treatments were associated with reduced levels of anti-Spike antibodies in patients. These observations have relevant implications for treated patients receiving BNT162b2 and the community.

Skin biopsy and quantitative sensory assessment in an Italian cohort of ATTRv patients with polyneuropathy and asymptomatic carriers: possible evidence of early non-length dependent denervation.

AIM: Study of intraepidermal nerve fiber density (IENFD) by skin biopsy represents a promising tool in the evaluation of patients with ATTRv polyneuropathy (ATTRv-PN). Herein, we retrospectively analyze intraepidermal innervation and quantitative sensory test (QST) data from an Italian cohort of Italian ATTRv-PN patients and asymptomatic carriers aimed to provide insights into early nerve pathological and functional changes in this disease. METHODS: IENFD and QST data of 14 ATTRv-PN patients and 14 asymptomatic carriers were retrospectively analyzed together with clinical and paraclinical data such as disease stage and severity, neuropathic pain scales, and sural SNAP amplitude. RESULTS: Given an estimated time to the predicted age of onset of symptomatic disease of 20.27 + / - 7.9 years, small nerve fiber loss seems to be unexpectedly early in carriers. Moreover, carriers showed skin denervation at the proximal (thigh) site, suggesting a non-length-dependent neuropathic process. IENFD at ankle correlated with disease severity and other paraclinical variables such as sural nerve potential amplitude and QST parameters. Patients at earlier stages of the disease did not show significant differences in ankle IENFD compared with asymptomatic carriers, but significant differences in terms of QST parameters, small fiber neuropathy symptoms, and neuropathic pain. CONCLUSIONS: Skin biopsy can disclose an early non-length-dependent small fiber loss in ATTRv-PN and, together with QST, could provide a useful insight disease onset and progression.

High-resolution ultrasound of peripheral nerves in late-onset hereditary transthyretin amyloidosis with polyneuropathy: similarities and differences with CIDP.

INTRODUCTION: Hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) remains a diagnostic challenge due to clinical, neurophysiological, and laboratory findings suggestive of other diagnoses, particularly chronic inflammatory demyelinating polyneuropathy (CIDP). In this cross-sectional prospective study, we aimed to investigate the utility of high-resolution ultrasonography of peripheral nerves as a diagnostic tool to differentiate ATTRv-PN from CIDP. METHODS: In 11 treatment-naive patients with genetically confirmed late-onset ATTRv-PN and 25 patients with CIDP, we collected clinical, electrodiagnostic, and high-resolution ultrasonography data of the peripheral nerves. In each patient, we used high-resolution ultrasonography to assess 26 nerve sites. RESULTS: Of the 11 patients with ATTRv-PN, two had electrodiagnostic study data compatible with a CIDP diagnosis. High-resolution ultrasonography showed that the cross-sectional area of the brachial plexus, median nerve at the axilla, arm, and forearm, ulnar nerve at the forearm, and peroneal nerve at the popliteal fossa were significantly smaller in the 11 ATTRv-PN patients than in CIDP patients. However, in the two patients with electrodiagnostic study data compatible with a CIDP diagnosis, high-resolution nerve ultrasonography data were comparable to those in patients with CIDP. CONCLUSION: Although high-resolution ultrasonography of peripheral nerves provides reliable information in patients with ATTRv-PN, its usefulness as a standalone diagnostic tool to differentiate ATTRv-PN from CIDP might be limited.

Changes of clinical, neurophysiological and nerve ultrasound characteristics in CIDP over time: a 3-year follow-up.

OBJECTIVES: To evaluate, in a prospective study, high-resolution ultrasound (HRUS) changes of nerve segments in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and their relationships with clinical and electrodiagnostic (EDX) characteristics. METHODS: Twenty-three consecutive patients with CIDP were included in a 3-year follow-up (FU) study. Each patient underwent neurologic examination, EDX and HRUS study. HRUS was performed on median, ulnar and peroneal nerves, yielding a total of 319 scanned nerve segments. INCAT and MRC-sum scores, motor nerve conduction velocity (NCV), compound muscle action potential (cMAP) amplitude, and nerve cross-sectional area (NCSA) were collected at baseline and at FU end, and were used for statistical analysis. Twenty-two healthy individuals, matched to patients for age and BMI, served as controls. RESULTS: NCSA was higher in patients than in controls (p < 0.0001) and showed significant direct correlation with disease severity, and inverse correlation with NCV and cMAP amplitude, both at baseline and at FU end. Disease duration, clinical scores and EDX were predictors of NCSA enlargement at both time points. During FU, NCSA increased in 51% of nerve segments (p = 0.006), in correlation with INCAT increase and with NCV and cMAP reduction. Considering EDX changes in subgroups that reflect the different types of nerve damage, NCSA significantly increased in those nerve segments that from normal EDX switched to prevalent myelinopathic EDX characteristics. CONCLUSIONS: Peripheral nerve size tends to increase over time in patients with CIDP, in correlation with clinical and EDX changes, in particular in those nerve segments that undergo a predominantly demyelinating damage.

Novel ACTA1 mutation causes late-presenting nemaline myopathy with unusual dark cores.

ACTA1 gene encodes the skeletal muscle alpha-actin, the core of thin filaments of the sarcomere. ACTA1 mutations are responsible of several muscle disorders including nemaline, cores, actin aggregate myopathies and fiber-type disproportion. We report clinical, muscle imaging, histopatological and genetic data of an Italian family carrying a novel ACTA1 mutation. All affected members showed a late-presenting, diffuse muscle weakness with sternocleidomastoideus and temporalis atrophy. Mild dysmorphic features were also detected. The most affected muscles by muscle MRI were rectus abdominis, gluteus minimus, vastus intermedius and both gastrocnemii. Muscle biopsy showed the presence of nemaline bodies with several unusual dark areas at Gomori Trichrome, corresponding to unstructured cores with abundant electrodense material by electron microscopy. The molecular analysis revealed missense variant c.148G>A; p.(Gly50Ser) in the exon 3 of ACTA1, segregating with affected members in the family. We performed a functional essay of fibre contractility showing a higher pCa50 (a measure of the calcium sensitivity of force) of type 1 fibers compared to control subjects' type 1 muscle fibers. Our findings expand the clinico-pathological spectrum of ACTA1-related congenital myopathies and the genetic spectrum of core-rod myopathies.

Iatrogenic Kaposi's sarcoma in myasthenia gravis: learnings from two case reports.

INTRODUCTION: Myasthenia gravis (MG) is an autoimmune neuromuscular disease whose treatment encompasses acetylcholinesterase inhibitors, oral steroids, and other immunosuppressants. Kaposi's sarcoma (KS) is a lymphangioproliferative disease associated with human herpesvirus 8 (HHV-8) infection and immunodeficiency or immunosuppression, mainly corticosteroids. CASE REPORTS: We present two cases of MG patients treated with oral steroids who developed KS. Patient 1 was diagnosed with three oral KS lesions. Prednisone was discontinued with lesion regression and stabilization, while azathioprine and pyridostigmine prompted control of MG. Patient 2 developed KS lesions on the trunk and lower limbs while taking prednisone and azathioprine. Steroid tapering was started but new oral and lymph nodal lesions appeared. Paclitaxel therapy was introduced and the patient experienced pulmonary embolism and developed sensitive neuropathy. Complete remission of KS lesions was achieved and maintained with azathioprine and pyridostigmine as MG medications. CONCLUSIONS: KS is an uncommon but clinically relevant adverse event (AE) often induced by steroid therapy. It can be controlled by steroid withdrawal but could necessitate chemotherapy, which associates with further potential AEs. Skin evaluation should be performed in all patients with chronic steroid therapy. Steroid-sparing strategies, including new drugs, could reduce KS and other steroid-related comorbidities. HHV-8 testing should be considered before starting chronic immunosuppression.

Gender effect on cardiac involvement in myotonic dystrophy type 1.

BACKGROUND AND PURPOSE: Cardiac involvement is observed in about 80% of subjects with myotonic dystrophy type 1 (DM1) and is mainly characterized by cardiac conduction and/or rhythm abnormalities (CCRAs), possibly leading to sudden cardiac death (SCD). Our objective was to investigate whether the gender difference may influence the cardiac involvement and SCD in DM1. METHODS: We analyzed prevalence and incidence of cardiological abnormalities in males versus females in 151 consecutive DM1 patients over a 35-year follow-up period. RESULTS: Fifty-five patients, 35 males (62.5%) and 20 females (42.5%), developed some type of CCRA during the follow-up period (mean 7.82 ± 6.21 years). CCRA overall, and specifically cardiac conduction abnormalities (CCAs), were significantly more frequent in males than in females (p = 0.043 and p = 0.031, respectively). CCRAs progressed in 16 males (45.7%) and six females (30%). Twenty-four patients, 14 males (25.0%) and 10 females (21.3%), died during the follow-up. Nine of them, six males (10.7%) and three females (6.4%), had SCD. After correction for Muscular Impairment Rating Scale progression, cytosine thymine-guanine expansion, and follow-up duration, a higher prevalence of CCAs was independently associated with male gender (p = 0.039), but independent association with gender was not detected for CCRAs overall, cardiac rhythm abnormalities, and SCD prevalence, even if prevalence was higher in males than females. CONCLUSIONS: The overall risk of occurrence of CCAs in DM1 is significantly higher in males than females regardless of genetic background and disease severity and progression. Moreover, the data also suggest a similar impact for male gender for CCRAs overall, CCAs, and SCD even if not statistically significant.

Complement Inhibition for the Treatment of Myasthenia Gravis.

Generalized myasthenia gravis (gMG) is a rare autoimmune disorder affecting the neuromuscular junction (NMJ). Approximately 80-90% of patients display antibodies directed against the nicotinic acetylcholine receptor (AChR). A major drive of AChR antibody-positive MG pathology is represented by complement activation. The role of the complement cascade has been largely demonstrated in patients and in MG animal models. Complement activation at the NMJ leads to focal lysis of the post-synaptic membrane, disruption of the characteristic folds, and reduction of AChR. Given that the complement system works as an activation cascade, there are many potential targets that can be considered for therapeutic intervention. Preclinical studies have confirmed the efficacy of complement inhibition in ameliorating MG symptoms. Eculizumab, an antibody directed towards C5, has recently been approved for the treatment of AChR antibody-positive gMG. Other complement inhibitors, targeting C5 as well, are currently under phase III study. Complement inhibitors, however, may present prohibitive costs. Therefore, the identification of a subset of patients more or less prone to respond to such therapies would be beneficial. For such purpose, there is a critical need to identify possible biomarkers predictive of therapeutic response, a field not yet sufficiently explored in MG. This review aims to give an overview of the complement cascade involvement in MG, the evolution of complement-inhibiting therapies and possible biomarkers useful to tailor and monitor complement-directed therapies.