Rituximab abrogates aquaporin-4-specific germinal center activity in patients with neuromyelitis optica spectrum disorders.

Neuromyelitis optica spectrum disorders (NMOSDs) are caused by immunoglobulin G (IgG) autoantibodies directed against the water channel aquaporin-4 (AQP4). In NMOSDs, discrete clinical relapses lead to disability and are robustly prevented by the anti-CD20 therapeutic rituximab; however, its mechanism of action in autoantibody-mediated disorders remains poorly understood. We hypothesized that AQP4-IgG production in germinal centers (GCs) was a core feature of NMOSDs and could be terminated by rituximab. To investigate this directly, deep cervical lymph node (dCLN) aspirates (n = 36) and blood (n = 406) were studied in a total of 63 NMOSD patients. Clinical relapses were associated with AQP4-IgM generation or shifts in AQP4-IgG subclasses (odds ratio = 6.0; range of 3.3 to 10.8; P < 0.0001), features consistent with GC activity. From seven dCLN aspirates of patients not administered rituximab, AQP4-IgGs were detected alongside specific intranodal synthesis of AQP4-IgG. AQP4-reactive B cells were isolated from unmutated naive and mutated memory populations in both blood and dCLNs. After rituximab administration, fewer clinical relapses (annual relapse rate of 0.79 to 0; P < 0.001) were accompanied by marked reductions in both AQP4-IgG (fourfold; P = 0.004) and intranodal B cells (430-fold; P < 0.0001) from 11 dCLNs. Our findings implicate ongoing GC activity as a rituximab-sensitive driver of AQP4 antibody production. They may explain rituximab's clinical efficacy in several autoantibody-mediated diseases and highlight the potential value of direct GC measurements across autoimmune conditions.

Immune Checkpoint Inhibitor-Related Cerebellar Toxicity: Clinical Features and Comparison with Paraneoplastic Cerebellar Ataxia.

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy, and the association with immune-related adverse events (irAEs) is well-established. However, cerebellar irAEs are poorly defined and their relationship with paraneoplastic disorders remains unclear. Our aim was (i) to characterize cerebellar irAE; (ii) to compare it with paraneoplastic cerebellar ataxia (PCA). We performed a multicenter, retrospective, cohort study of patients developing new-onset, immune-mediated, isolated/predominant cerebellar dysfunction after ICI administration. In addition, a systematic review following PRISMA guidelines was performed. Cerebellar irAE cases were compared with a consecutive cohort of patients with PCA. Overall, 35 patients were included, of whom 12 were original cases (males: 25/35 (71%), median age: 65 [range: 20-82]). The most frequent tumor was non-small cell lung cancer (12/35, 34%). Anti-PD1 were adopted in 19/35 (54%). Symptoms developed at a median of 11 weeks after ICI onset. Neuronal antibodies were detected in 15/31 patients tested (48%). Cerebrospinal fluid was inflammatory in 25/30 (83%). Magnetic resonance imaging showed cerebellar hyperintensities in 8/35 (23%). Immunotherapy was applied in 33/35 cases (94%), and most patients improved with residual disability (16/35, 46%). When compared with a series of PCA (n = 15), the cerebellar irAE group was significantly more associated with male sex, lung cancer (rather than gynecological/breast cancers), isolated ataxia, and a better outcome. We provide a detailed characterization of cerebellar irAE. Compared to PCA, differences exist in terms of tumor association, clinical features, and outcome. Clinical presentation-antibody-tumor triad in the ICI group only partially reflects the associations described in paraneoplastic disorders.

Epidemiology of seropositive myasthenia gravis in Sardinia: A population-based study in the district of Sassari.

INTRODUCTION/AIMS: The global incidence and prevalence of myasthenia gravis (MG) range between 6-31/million and 10-37/100,000, respectively. Sardinia is a high-risk region for different immune-mediated disorders, but the epidemiology of MG remains unclear. We determined the epidemiology of MG with acetylcholine receptor (AChR)-immunoglobulin G (IgG) and muscle-specific tyrosine kinase (MuSK)-IgG in the district of Sassari (North-Western Sardinia; population, 325,288). METHODS: From the laboratory of the University Hospital of Sassari (reference for AChR/MuSK-IgG testing in Sardinia since 1998) and the main neurology units in Sardinia, we retrospectively identified MG patients with (1) AChR-IgG and/or MuSK-IgG positivity by radioimmunoprecipitation assay; and (2) residency in the district of Sassari. Incidence (January 2010-December 2019) and prevalence (December 31, 2019) were calculated. RESULTS: A total of 202 patients were included (incident, 107; prevalent, 180). Antibody specificities were AChR (n = 187 [93%]) and MuSK (n = 15 [7%]). The crude MG incidence (95% confidence interval) was 32.6 (26.8-39.2)/million, while prevalence was 55.3 (47.7-63.9)/100,000. After age-standardization to the world population, incidence decreased to 18.4 (14.3-22.5)/million, while prevalence decreased to 31.6 (26.1-37.0)/100,000. Among incident cases, age strata (years) at MG onset were: <18 (2%), 18-49 (14%), 50-64 (21%), and ≥65 (63%). DISCUSSION: Sardinia is a high-risk region for MG, with a prevalence that exceeds the European threshold for rare disease. Identification of the environmental and genetic determinants of this risk may improve our understanding of disease pathophysiology.

Efficacy and safety of rituximab in myelin oligodendrocyte glycoprotein antibody-associated disorders compared with neuromyelitis optica spectrum disorder: a systematic review and meta-analysis.

BACKGROUND: Rituximab (RTX) efficacy in patients with myelin oligodendrocyte glycoprotein (MOG) antibody-associated disorders (MOGADs) is still poorly understood, though it appears to be lower than in aquaporin-4-IgG-positive neuromyelitis optica spectrum disorders (AQP4-IgG+NMOSDs). The aim of this systematic review and meta-analysis is to assess the efficacy and safety profile of RTX in patients with MOGAD and to compare RTX efficacy between MOGAD and AQP4-IgG+NMOSD. METHODS: We searched original English-language articles published between 2012 and 2021 in MEDLINE, Cochrane, Central Register of Controlled Trials and clinicaltrials.gov, reporting data on RTX efficacy in patients with MOGAD. The main outcome measures were annualised relapse rate (ARR) and Expanded Disability Status Scale (EDSS) score mean differences (MDs) after RTX. The meta-analysis was performed with a random effects model. Covariates associated with the outcome measures were analysed with a linear meta-regression. RESULTS: The systematic review included 315 patients (138 women, mean onset age 26.8 years) from 32 studies. Nineteen studies (282 patients) were included in the meta-analysis. After RTX, a significant decrease of ARR was found (MD: -0.92, 95% CI -1.24 to -0.60, p<0.001), markedly different from the AQP4-IgG+NMOSD (MD: -1.73 vs MOGAD -0.92, subgroup difference testing: Q=9.09, p=0.002). However, when controlling for the mean ARR pre-RTX, this difference was not significant. After RTX, the EDSS score decreased significantly (MD: -0.84, 95% CI -1.41 to -0.26, p=0.004). The frequency of RTX-related adverse events was 18.8% (36/192) and overall RTX-related mortality 0.5% (1/192). CONCLUSIONS: RTX showed effective in MOGAD, although to a lesser extent than in AQP4-IgG+NMOSD, while the safety profile warrants some caution in its prescription. Randomised-controlled trials are needed to confirm these findings and provide robust evidence to improve treatment strategies in patients with MOGAD. PROSPERO REGISTRATION NUMBER: CRD42020175439.

Cervical lymph nodes and ovarian teratomas as germinal centres in NMDA receptor-antibody encephalitis.

Autoantibodies against the extracellular domain of the N-methyl-d-aspartate receptor (NMDAR) NR1 subunit cause a severe and common form of encephalitis. To better understand their generation, we aimed to characterize and identify human germinal centres actively participating in NMDAR-specific autoimmunization by sampling patient blood, CSF, ovarian teratoma tissue and, directly from the putative site of human CNS lymphatic drainage, cervical lymph nodes. From serum, both NR1-IgA and NR1-IgM were detected more frequently in NMDAR-antibody encephalitis patients versus controls (both P < 0.0001). Within patients, ovarian teratoma status was associated with a higher frequency of NR1-IgA positivity in serum (OR = 3.1; P < 0.0001) and CSF (OR = 3.8, P = 0.047), particularly early in disease and before ovarian teratoma resection. Consistent with this immunoglobulin class bias, ovarian teratoma samples showed intratumoral production of both NR1-IgG and NR1-IgA and, by single cell RNA sequencing, contained expanded highly-mutated IgA clones with an ovarian teratoma-restricted B cell population. Multiplex histology suggested tertiary lymphoid architectures in ovarian teratomas with dense B cell foci expressing the germinal centre marker BCL6, CD21+ follicular dendritic cells, and the NR1 subunit, alongside lymphatic vessels and high endothelial vasculature. Cultured teratoma explants and dissociated intratumoral B cells secreted NR1-IgGs in culture. Hence, ovarian teratomas showed structural and functional evidence of NR1-specific germinal centres. On exploring classical secondary lymphoid organs, B cells cultured from cervical lymph nodes of patients with NMDAR-antibody encephalitis produced NR1-IgG in 3/7 cultures, from patients with the highest serum NR1-IgG levels (P < 0.05). By contrast, NR1-IgG secretion was observed neither from cervical lymph nodes in disease controls nor in patients with adequately resected ovarian teratomas. Our multimodal evaluations provide convergent anatomical and functional evidence of NMDAR-autoantibody production from active germinal centres within both intratumoral tertiary lymphoid structures and traditional secondary lymphoid organs, the cervical lymph nodes. Furthermore, we develop a cervical lymph node sampling protocol that can be used to directly explore immune activity in health and disease at this emerging neuroimmune interface.

Clinical value of cell-based assays in the characterisation of seronegative myasthenia gravis.

OBJECTIVE: Patients with myasthenia gravis without acetylcholine receptor (AChR) or muscle-specific kinase (MuSK) antibodies detected by radioimmunoprecipitation assays (RIAs) are classified as seronegative myasthenia gravis (SNMG). Live cell-based assays (l-CBAs) can detect additional antibodies to clustered AChR, MuSK and low-density lipoprotein receptor-related protein 4 (LRP4), but positivity rates are variable and both clinical relevance and utility of CBA platforms remain unclear. METHODS: Sera from 82 patients with SNMG were tested by l-CBAs. Human embryonic kidney cells were transfected to individually express clustered AChR, MuSK or LRP4; or transfected to jointly express both clustered adult AChR and MuSK. Sera from 30 and 20 patients positive by RIA for AChR or MuSK antibodies were used as comparators. RESULTS: 53 of 82 (72%) patients with SNMG had generalised and 29 (28%) had ocular disease. The clustered AChR CBA detected antibodies in 16 of 82 patients (19.5%; including 4 patients with solely fetal AChR antibodies), while 7 of 82 (8.5%) patients had MuSK antibodies. A novel exploratory combined adult AChR-MuSK l-CBA efficiently detected all these antibodies in a subset of the SNMG cohort. No LRP4 antibodies were identified. Overall, patients with SNMG with clustered AChR antibodies, CBA-positive MuSK-MG or triple seronegative were younger, had less severe disease than patients with RIA-positive MG and had a better clinical outcome when immunotherapy was started soon after disease onset, although the time interval from onset to immunotherapy was not different when compared with patients with RIA-positive MG. CONCLUSION: Around one-third of patients with SNMG had AChR or MuSK antibodies by l-CBAs, which were efficiently detected with a combined l-CBA. The results in this large and unselected cohort of patients with MG demonstrate the diagnostic usefulness of performing CBAs and the importance of making these tests more widely available.

Safety and tolerability of SARS-Cov-2 vaccination in patients with myasthenia gravis: A multicenter experience.

BACKGROUND AND PURPOSE: During the COVID-19 pandemic, myasthenia gravis (MG) patients have been identified as subjects at high risk of developing severe COVID-19, and thus were offered vaccination with priority. The lack of direct data on the safety and tolerability of SARS-CoV-2 vaccines in MG have contributed to vaccine hesitancy. To address this issue, the safety and tolerability of SARS-CoV-2 vaccines were assessed in a large cohort of MG patients from two referral centers. METHODS: Patients with confirmed MG diagnosis, consecutively seen between October and December 2021 at two MG centers, were enrolled. Demographics, clinical characteristics, and information regarding SARS-CoV-2 infection/vaccination were extracted from medical reports and/or collected throughout telephonic or in-person interviews. RESULTS: Ninety-eight (94.2%) of 104 patients included were administered at least two vaccine doses 4 weeks before the interview or earlier, and among them, 63 of 98 (64.2%) have already received the "booster" dose. The most frequently used vaccines were BNT162b2-Pfizer-BioNTech and mRNA-1273-Moderna. Overall, only minor side effects were reported, most commonly local pain and fever. MG worsening after vaccination was observed in eight of 104 (7.7%) cases. The frequency of worsening among muscle-specific tyrosine kinase MG cases (3/9, 33.3%) was significantly higher compared to other serological subgroups. Spontaneous symptom regression was observed in six of eight cases. Twelve of 104 (11.5%) patients had SARS-CoV-2 infection, and none of the SARS-CoV-2-infected MG patients worsened after vaccination. CONCLUSIONS: Our data support the safety and tolerability of mRNA COVID-19 vaccines, which should be strongly recommended in MG patients, who could be at higher risk of complications if exposed to SARS-CoV-2 infection.

Clinical features and outcome of patients with autoimmune cerebellar ataxia evaluated with the Scale for the Assessment and Rating of Ataxia.

BACKGROUND AND PURPOSE: This study was undertaken to assess the long-term outcome of patients with paraneoplastic and non paraneoplastic autoimmune cerebellar ataxia (ACA) using the Scale for the Assessment and Rating of Ataxia (SARA). METHODS: Patients with subacute cerebellar ataxia admitted to our institution between September 2012 and April 2020 were prospectively recruited. Serum and/or cerebrospinal fluid was tested for neural autoantibodies by indirect immunofluorescence on mouse brain, cell-based assays, and radioimmunoassay. SARA and modified Rankin Scale (mRS) score were employed to assess patients' outcome. RESULTS: Fifty-five patients were recruited, of whom 23 (42%) met the criteria for cerebellar ataxia of autoimmune etiology. Neural autoantibodies were detected in 22 of 23 patients (Yo-immunoglobulin G [IgG], n = 6; glutamic acid decarboxylase 65-IgG, n = 3; metabotropic glutamate receptor 1-IgG, n = 2; voltage-gated calcium channel P/Q type-IgG, n = 2; Hu-IgG, n = 1; glial fibrillary acidic protein-IgG, n = 1; IgG-binding unclassified antigens, n = 7). Thirteen patients were diagnosed with paraneoplastic cerebellar syndrome (PCS) and 10 with idiopathic ACA. All patients received immunotherapy. Median SARA score was higher in the PCS group at all time points (p = 0.0002), while it decreased significantly within the ACA group (p = 0.049) after immunotherapy. Patients with good outcome (mRS ≤ 2) had less neurological disability (SARA < 15) at disease nadir (p = 0.039) and presented less frequently with paraneoplastic neurological syndrome (p = 0.0028). The univariate linear regression model revealed a good correlation between mRS and SARA score both at disease onset (p < 0.0001) and at last follow-up (p < 0.0001). SARA score < 11 identified patients with good outcome. CONCLUSIONS: Patients with idiopathic ACA significantly improved after immunotherapy. SARA score accurately reflects patients' clinical status and may be a suitable outcome measure for patients with ACA.

Myasthenia gravis associated with anti-MuSK antibodies developed after SARS-CoV-2 infection.

INTRODUCTION: Since the onset of the novel coronavirus pandemic, several neurological complications secondary to SARS-CoV-2 infection have been reported, affecting central nervous system, peripheral nervous system and neuromuscular junction. CASE REPORT: We present the case of a 77-year-old man who developed bulbar myasthenia gravis (MG) eight weeks after SARS-CoV-2 infection. The search for serum antibodies against the acetylcholine receptor and the muscle-specific tyrosine kinase (MuSK), performed by radioimmunoassay (RIA), and the search of low-density lipoprotein receptor-related protein 4 antibodies, performed by immunohistochemistry, resulted negative, while anti-MuSK antibodies were detected by cell-based assay (CBA). The patient was treated with pyridostigmine (60 mg four times a day) with unsatisfactory clinical response, followed by immunosuppressive therapy (azathioprine 1.5 mg/kg/day) with improvement of MG symptoms after two months of treatment. DISCUSSION: Several viral diseases have been described as associated with the onset of MG, although the underlying mechanisms are not yet fully understood. Similarly, a growing number of scientific reports suggest a correlation between SARS-CoV-2 infection and autoimmune diseases. The interest of our case lies in the timing of the MG onset (after 2 months from infection), together with the unusual late onset of anti-MuSK MG. These elements suggest that coronavirus infection may act as a trigger of the disease. We confirm the importance of CBA in the serological diagnosis of RIA-negative MG.

Benefit and danger from immunotherapy in myasthenia gravis.

In the last years, significant advances have improved the knowledge of myasthenia gravis (MG) immunopathogenesis and have enabled to realize new molecules with a selective action targeting compounds of the immunological system. This review discusses emerging treatments for MG, including complement inhibitors, neonatal Fc receptor targeting agents, and B cell interfering drugs, focusing on benefit and danger. In the second section of the review, several related adverse events of immunotherapy, including MGonset, are debated.

Clinical and immunological characteristics of the spectrum of GFAP autoimmunity: a case series of 22 patients.

OBJECTIVE: To report the clinical and immunological characteristics of 22 new patients with glial fibrillar acidic protein (GFAP) autoantibodies. METHODS: From January 2012 to March 2017, we recruited 451 patients with suspected neurological autoimmune disease at the Catholic University of Rome. Patients' serum and cerebrospinal fluid (CSF) samples were tested for neural autoantibodies by immunohistochemistry on mouse and rat brain sections, by cell-based assays (CBA) and immunoblot. GFAP autoantibodies were detected by immunohistochemistry and their specificity confirmed by CBA using cells expressing human GFAPα and GFAPδ proteins, by immunoblot and immunohistochemistry on GFAP-/- mouse brain sections. RESULTS: Serum and/or CSF IgG of 22/451 (5%) patients bound to human GFAP, of which 22/22 bound to GFAPα, 14/22 to both GFAPα and GFAPδ and none to the GFAPδ isoform only. The neurological presentation was: meningoencephalomyelitis or encephalitis in 10, movement disorder (choreoathetosis or myoclonus) in 3, anti-epileptic drugs (AED)-resistant epilepsy in 3, cerebellar ataxia in 3, myelitis in 2, optic neuritis in 1 patient. Coexisting neural autoantibodies were detected in five patients. Six patients had other autoimmune diseases. Tumours were found in 3/22 patients (breast carcinoma, 1; ovarian carcinoma, 1; thymoma, 1). Nineteen patients were treated with immunotherapy and 16 patients (84%) improved. Histopathology analysis of the leptomeningeal biopsy specimen from one patient revealed a mononuclear infiltrate with macrophages and CD8+ T cells. CONCLUSIONS: GFAP autoimmunity is not rare. The clinical spectrum encompasses meningoencephalitis, myelitis, movement disorders, epilepsy and cerebellar ataxia. Coexisting neurological and systemic autoimmunity are relatively common. Immunotherapy is beneficial in most cases.

The clinical features, underlying immunology, and treatment of autoantibody-mediated movement disorders.

An increasing number of movement disorders are associated with autoantibodies. Many of these autoantibodies target the extracellular domain of neuronal surface proteins and associate with highly specific phenotypes, suggesting they have pathogenic potential. Below, we describe the phenotypes associated with some of these commoner autoantibody-mediated movement disorders, and outline increasingly well-established mechanisms of autoantibody pathogenicity which include antigen downregulation and complement fixation. Despite these advances, and the increasingly robust evidence for improved clinical outcomes with early escalation of immunotherapies, the underlying cellular immunology of these conditions has received little attention. Therefore, here, we outline the likely roles of T cells and B cells in the generation of autoantibodies, and reflect on how these may guide both current immunotherapy regimes and our future understanding of precision medicine in the field. In addition, we summarise potential mechanisms by which these peripherally-driven immune responses may reach the central nervous system. We integrate this with the immunologically-relevant clinical observations of preceding infections, tumours and human leucocyte antigen-associations to provide an overview of the therapeutically-relevant underlying adaptive immunology in the autoantibody-mediated movement disorders. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Pattern of ocular involvement in myasthenia gravis with MuSK antibodies.

BACKGROUND: Myasthenia gravis (MG) with antibodies to the muscle-specific kinase (MuSK) has a characteristic phenotype. Ocular manifestations have not been systematically evaluated. OBJECTIVE: To investigate the features of extrinsic ocular muscle involvement in patients with MuSK-MG. METHODS: We retrospectively evaluated the prevalence, time of onset, clinical pattern and outcome of ocular symptoms in 82 patients with a clinical follow-up ≥2 years. RESULTS: Ocular manifestations were observed in 79 patients (96.4%) and were the presenting symptoms in 48 (58.5%). Intermittent diplopia with subtle ophthalmoparesis was the most common complaint, ptosis was generally symmetrical and conjugated gaze paresis occurred in 35% of the patients. Ocular manifestations responded well to prednisone and partially to symptomatic treatment. A few patients developed chronic symmetrical ophthalmoparesis, associated with persistent weakness in other muscle groups. All patients with ocular presentation progressed to generalised disease, though weakness spread to other muscle groups was considerably delayed in a few cases. CONCLUSIONS: In MG with antibodies to MuSK, ocular manifestations were as frequent as in other disease subtypes. Symmetrical ophthalmoparesis with conjugated gaze limitation was rather common and associated with low functional disability. A proportion of these patients developed chronic eye muscle paresis.

Neuromyelitis optica spectrum disorder as a paraneoplastic manifestation of lung adenocarcinoma expressing aquaporin-4.

BACKGROUND: The observations of neuromyelitis optica spectrum disorders (NMOSD) occurring in the setting of cancer suggest that aquaporin-4 (AQP4) autoimmunity may in some cases be paraneoplastic. RESULTS: We describe a 72-year-old patient who developed a longitudinally extensive transverse myelitis associated with AQP4 autoantibodies in the setting of a lung adenocarcinoma recurrence. AQP4 expression was demonstrated in tumor cells. IgG in patient's cerebrospinal fluid bound to tumor cells co-localizing with AQP4 immunoreactivity. CONCLUSIONS AND RELEVANCE: This case expands the spectrum of paraneoplastic AQP4 autoimmunity highlighting the importance of considering an oncological screening in patients with late-onset NMOSD.

Distinct lymphocytes subsets in IgM-related neuropathy: clinical-immunological correlations.

IgM-related neuropathy generally presents as a late-onset demyelinating polyneuropathy with predominant sensory loss and ataxia. However, we recently reported the clinical, neurophysiological and pathological findings from our cohort and identified in about a third of patients an atypical phenotype. We analyzed by flow cytometry the different lymphocytes subsets in the peripheral blood of patients affected by IgM-related neuropathy, chronic inflammatory demyelinating polyneuropathy (CIDP), monoclonal gammopathy of undetermined significance and healthy subjects, to investigate whether different immunological patterns may differentiate the classical phenotype from atypical forms. IFN-gamma producing CD4+ and CD8+ T lymphocytes, as well as CD4+ and CD8+ T cells expressing T-bet (T-helper type 1, Th1) were increased in CIDP patients. The percentage of circulating CD4+ and CD8+ T cells producing IL-10 as well as the percentage of CD19+ cells expressing Blimp-1 were higher in patients with IgM-neuropathy. We did not find any significant differences in the different lymphocytes subsets in the IgM-related neuropathy between patients with classical and atypical phenotype. Th1 cells are increased in CIDP patients while a T helper type 2-phenotype seems to prevail in patients with IgM-neuropathy. Further studies involving a larger patient population are needed to evaluate if different lymphocytes subset may be involved in different clinical phenotypes of IgM-related neuropathy.

Serological Markers of Clinical Improvement in MuSK Myasthenia Gravis.

BACKGROUND AND OBJECTIVES: In this retrospective longitudinal study, we aimed at exploring the role of (a) MuSK-immunoglobulin G (IgG) levels, (b) predominant MuSK-IgG subclasses, and (c) antibody affinity as candidate biomarkers of severity and outcomes in MuSK-MG, using and comparing different antibody testing techniques. METHODS: Total MuSK-IgGs were quantified with radioimmunoassay (RIA), ELISA, flow cytometry, and cell-based assay (CBA) serial dilutions using HEK293 cells transfected with MuSK-eGFP. MuSK-IgG subclasses were measured by flow cytometry. SAffCon assay was used for determining MuSK-IgG affinity. RESULTS: Forty-three serum samples were obtained at different time points from 20 patients with MuSK-MG (median age at onset: 48 years, interquartile range = 27.5-72.5; women, 16/20), with 9 of 20 (45%) treated with rituximab. A strong correlation between MuSK-IgG levels measured by flow cytometry and RIA titers was found (rs = 0.74, 95% CI 0.41-0.89, p = 0.0003), as well as a moderate correlation between CBA end-point titers and RIA titers (rs = 0.47, 95% CI 0.01-0.77, p = 0.0414). A significant correlation was found between MuSK-IgG flow cytometry levels and disease severity (rs = 0.39, 95% CI 0.06-0.64, p = 0.0175; mixed-effects model estimate: 2.296e-06, std. error: 1.024e-06, t = 2.243, p = 0.032). In individual patients, clinical improvement was associated with decrease in MuSK-IgG levels, as measured by either flow cytometry or CBA end-point titration. In all samples, MuSK-IgG4 was the most frequent isotype (mean ± SD: 90.95% ± 13.89). A significant reduction of MuSK-IgG4 and, to a lesser extent, of MuSK-IgG2, was seen in patients with favorable clinical outcomes. A similar trend was confirmed in the subgroup of rituximab-treated patients. In a single patient, MuSK-IgG affinity increased during symptom exacerbation (KD values: 62 nM vs 0.6 nM) while total MuSK-IgG and IgG4 levels remained stable, suggesting that affinity maturation may be a driver of clinical worsening. DISCUSSION: Our data support the quantification of MuSK antibodies by flow cytometry. Through a multimodal investigational approach, we showed that total MuSK-IgG levels, MuSK-IgG4 and MuSK-IgG2 levels, and MuSK-IgG affinity may represent promising biomarkers of disease outcomes in MuSK-MG.

Leptomeningeal enhancement in multiple sclerosis: a focus on patients treated with hematopoietic stem cell transplantation.

Background: Leptomeningeal enhancement (LME) is considered an MRI marker of leptomeningeal inflammation in inflammatory neurological disorders, including multiple sclerosis (MS). To our knowledge, no disease-modifying therapies (DMTs) have been demonstrated to affect LME number or morphology so far. Methods: Monocentric study investigating the frequency and number of LME in a cohort of people with (pw)MS who performed a 3 T brain MRI with a standardized protocol (including a post-contrast FLAIR sequence), and exploring the impact of autologous hematopoietic stem cell transplantation (AHSCT) on this marker. In a longitudinal pilot study, consecutive MRIs were also analyzed in a subgroup of pwMS, including patients evaluated both pre- and post-AHSCT. Results: Fifty-five pwMS were included: 24/55 (44%) had received AHSCT (AHSCT group) and 31 other treatments (CTRL group). At least one LME was identified in 19/55 (35%) cases (42 and 29% in the AHSCT and CTRL groups, respectively; p = 0.405). In the AHSCT group, LME number correlated with age at AHSCT (R = 0.50; p = 0.014), but not with age at post-treatment MRI. In the longitudinal pilot study (n = 8), one LME disappeared following AHSCT in 1/4 patients, whereas LME number was unchanged in the remaining four pwMS from the CTRL group. Discussion: These results suggest that AHSCT may affect development and persistence of LME, strengthening the indication for early use of effective therapies bioavailable within the central nervous system (CNS), and therefore potentially targeting compartmentalized inflammation.

Clinical Course of Neurologic Adverse Events Associated With Immune Checkpoint Inhibitors: Focus on Chronic Toxicities.

BACKGROUND AND OBJECTIVES: The clinical course and the risk of chronicity of neurologic immune-related adverse events (n-irAEs) associated with immune checkpoint inhibitors (ICIs) are not well documented. This study aimed to characterize the clinical course of n-irAEs and assess the prevalence of chronic events. METHODS: This nationwide, multicenter, retrospective study included patients with n-irAEs identified at 7 Italian hospitals. The clinical course of n-irAEs was categorized into fulminant (if resulted in death within 12 weeks), monophasic (if resolved within 12 weeks), and chronic (if persisted beyond 12 weeks). Chronic n-irAEs were further subdivided into active (if there was indirect evidence of ongoing inflammation [i.e., required ongoing immunosuppression, relapsed on steroid tapering, or exhibited neurologic progression]) and inactive (if patients had neurologic sequelae without ongoing inflammation). Comparisons between groups and time-to-death analyses were performed. RESULTS: Sixty-six patients were included (median age: 69 years [IQR 62-75]; 53 [80%] men). n-irAEs involved the peripheral nervous system in 48 patients (73%), the central nervous system in 14 (21%), and both in 4 (6%). Twelve patients (18%) had a fulminant course, with the risk being significantly higher in those with concurrent myocarditis (OR 5.4; 95% CI [1.02-28.31]). Among 54 patients with a nonfulminant course, 23 (43%) had a monophasic n-irAE and 31 (57%) had a chronic n-irAE, of which 16 of 31 (52%) were chronic active (due to ongoing immunosuppression [69%], relapses at corticosteroid tapering [19%], or neurologic disease progression [12%]) and 15 of 31 (48%) were chronic inactive. In patients with chronic inactive n-irAEs, neurologic sequelae included cerebellar ataxia (33%), neuromuscular weakness (27%), visual loss (13%), sensory disturbances (13%), focal neurologic signs (7%), and cognitive impairment (7%). Compared with patients with monophasic events, those with chronic n-irAEs had a higher rate of severe neurologic disability at the last evaluation (p < 0.01), shorter survival (p < 0.01), and higher overall mortality (p < 0.01), primarily due to cancer progression. DISCUSSION: More than half of the patients with n-irAEs who survived the acute phase developed a chronic condition. Patients with chronic n-irAEs were at higher risk of death, mainly due to cancer progression. Future studies are needed to further characterize chronic n-irAEs and identify optimal long-term management strategies.

Conventional and emerging treatments and controversies in myasthenia gravis.

INTRODUCTION: Myasthenia gravis (MG) is caused by IgG antibodies against different proteins at the neuromuscular junction. Anti-acetylcholine receptor (AChR) Abs are detected in the great majority of patients. MG management consists of long-term immunotherapy, based on steroids and immunosuppressants, short-term treatments and therapeutic thymectomy. Targeted immunotherapies that reduce B cell survival, inhibit complement activation, and decrease serum IgG concentration have been evaluated in trials and have entered clinical practice. AREAS COVERED: Herein, the efficacy and safety data of conventional and novel therapeutic options are reviewed and their indications in the disease subtypes are discussed. EXPERT OPINION: Even though conventional treatment is generally effective, 10-15% of patients have refractory disease and there are safety concerns related to long-term immunosuppression. Novel therapeutic options offer several advantages but also have limitations. Safety data based on long-term treatment are not yet available for some of these agents. The mechanisms of action of new drugs and the immunopathogenesis of different MG subtypes must be considered in therapy decision making. Integrating new agents in the treatment scenario of MG can significantly improve disease management.