Pharmacotherapy for Neuromyelitis Optica Spectrum Disorders: Current Management and Future Options

Aquaporin 4 and the endocannabinoid system: a potential therapeutic target in brain injury

Brain edema is a critical complication arising from stroke and traumatic brain injury (TBI) with an important impact on patient recovery and can lead to long-term consequences. Therapeutic options to reduce edema progression are limited with variable patient outcomes. Aquaporin 4 (AQP4) is a water channel that allows bidirectional water diffusion across the astrocyte membrane and participates in the distinct phases of cerebral edema. The absence or inhibition of this channel has been demonstrated to ameliorate edema and brain damage. The endocannabinoid system (ECS) is a neuromodulator system with a wide expression in the brain and its activation has shown neuroprotective properties in diverse models of neuronal damage. This review describes and discusses the major features of ECS and AQP4 and their role during brain damage, observing that ECS stimulation reduces edema and injury size in diverse models of brain damage, however, the relationship between AQP4 expression and dynamics and ECS activation remains unclear. The research on these topics holds promising therapeutic implications for the treatment of brain edema following stroke and TBI.

Mitoxantrone in NMO Spectrum Disorder in a Large Multicenter Cohort in French Caribbean

BACKGROUND AND OBJECTIVES

Preventing relapses in neuromyelitis Optica spectrum disorder (NMOSD) is a primary goal. New effective molecules are often expensive and not readily available in regions with fragile health systems. Assessing the efficacy and safety of less costly therapeutic alternatives is necessary. We aim to evaluate the efficacy and safety of mitoxantrone (MiTX) in NMOSD.

METHODS

This is an observational, multicenter, open study of 86 NMOSD-treated patients with prospective follow-up over 30 years. The first endpoint was the first relapse at the 96-week follow-up. The secondary endpoints were to evaluate the median delay to relapse, the annualized relapse rate (ARR), and the Expanded Disability Status Scale (EDSS) at 96 weeks of follow-up and to assess risk factors of relapse and the occurrence of severe adverse effects.

RESULTS

At 96-week follow-up, 71% of our patients were relapse-free, and it was 87% when patients were treated with MiTX from the first attack. The ARR dropped from 0.85 (±0.55) to 0.32 (±0.63) (p < 0.001) and EDSS from 4.9 (±2.4) to 4.2 (±2.6) (p < 0.001). AQP4-IgG seropositivity (hazard ratio [HR] 12.3, 95% CI 1.64-91.6, p = 0.015), a delay between the first attack and MiTX ≥24 months (HR 2.76, 95% CI 1.23-6.17, p = 0.014), and a pretreatment ARR ≥1 (HR 2.38, 95% CI 1.05-5.39, p = 0.037) were predictors of relapse. During the entire follow-up, severe secondary adverse events occurred in 3 patients (3.5%).

DISCUSSION

MiTX is an effective and safe treatment for most of our patients, drastically less expensive than new molecules, and could be allowed in NMOSD Afro-descendant patients in geographical areas where access to care is difficult.

Tocilizumab treatment in neuromyelitis optica spectrum disorders: Updated meta-analysis of efficacy and safety

This systematic review and meta-analysis summarize the efficacy and safety of Tocilizumab (TCZ) in treating NMOSD and investigates the factors that affect its efficacy. TCZ is the first monoclonal antibody against the IL-6 receptor for treating NMOSD, and its efficacy and safety vary in different studies. We collected English-language research literature until January 1, 2023, by searching databases such as PubMed, MEDLINE, Embase, Cochrane Library, and clinicaltrials.gov, and identified 9 studies involving 153 patients (139 female and 14 male) that met our inclusion criteria. In these studies, the average ARR ratio and EDSS score reduction values in the TCZ treatment group were -1.34 (95 % CI, -1.60 to -1.09) and -0.81 (95 % CI, -1.04 to -0.58), respectively. Based on the data we have collected, compared to the AQP4-IgG negative NMOSD patients, TCZ demonstrates a more pronounced effectiveness in AQP4-IgG positive NMOSD patients. The study also found that the effectiveness of TCZ in reducing NMOSD patients' ARR ratio was related to gender, race, and TCZ dosage, while the effectiveness of reducing EDSS score was not related to these factors. Among the 153 patients receiving TCZ treatment, 101 (66 %) experienced mild adverse reactions, and one patient experienced a severe adverse reaction (facial cellulitis). The comprehensive data indicate that TCZ treatment can reduce the frequency of NMOSD relapses, improve patients' neurological function, and have good safety. The effectiveness of TCZ in reducing NMOSD patients' ARR ratio is related to multiple factors.

Double-negative neuromyelitis optica spectrum disorder

Most patients with neuromyelitis optica spectrum disorders (NMOSD) test positive for aquaporin-4 antibody (AQP4-IgG) or myelin oligodendrocyte glycoprotein antibodies (MOG-IgG). Those who are negative are termed double-negative (DN) NMOSD and may constitute a diagnostic and therapeutic challenge. DN NMOSD is a syndrome rather than a single disease, ranging from a (postinfectious) monophasic illness to a more chronic syndrome that can be indistinguishable from AQP4-IgG+ NMOSD or develop into other mimics such as multiple sclerosis. Thus, underlying disease mechanisms are likely to be heterogeneous. This topical review aims to (1) reappraise antibody-negative NMOSD definition as it has changed over time with the development of the AQP4 and MOG-IgG assays; (2) outline clinical characteristics and the pathophysiological nature of this rare entity by contrasting its differences and similarities with antibody-positive NMOSD; (3) summarize laboratory characteristics and magnetic resonance imaging findings of DN NMOSD; and (4) discuss the current treatment for DN NMOSD.

Inhibition of complement C3 signaling ameliorates locomotor and visual dysfunction in autoimmune inflammatory diseases

Neuromyelitis optica (NMO) is an autoimmune inflammatory disease of the central nervous system (CNS) characterized by transverse myelitis and optic neuritis. The pathogenic serum IgG antibody against the aquaporin-4 (AQP4) on astrocytes triggers the activation of the complement cascade, causing astrocyte injury, followed by oligodendrocyte injury, demyelination, and neuronal loss. Complement C3 is positioned as a central player that relays upstream initiation signals to activate downstream effectors, potentially stimulating and amplifying host immune and inflammatory responses. However, whether targeting the inhibition of C3 signaling could ameliorate tissue injury, locomotor defects, and visual impairments in NMO remains to be investigated. In this study, using the targeted C3 inhibitor CR2-Crry led to a significant decrease in complement deposition and demyelination in both slice cultures and focal intracerebral injection models. Moreover, the treatment downregulated the expression of inflammatory cytokines and improved motor dysfunction in a systemic NMO mouse model. Similarly, employing serotype 2/9 adeno-associated virus (AAV2/9) to induce permanent expression of CR2-Crry resulted in a reduction in visual dysfunction by attenuating NMO-like lesions. Our findings reveal the therapeutic value of inhibiting the complement C3 signaling pathway in NMO.

French national diagnostic and care protocol for Sjögren's disease

Sjögren's disease (SD), also known as Sjögren's syndrome (SS) or Gougerot-Sjögren's syndrome in France, is a rare systemic autoimmune disease in its primary form and is characterised by tropism for the exocrine glandular epithelia, particularly the salivary and lacrimal glands. The lymphocytic infiltration of these epithelia will clinically translate into a dry syndrome which, associated with fatigue and pain, constitutes the symptom triad of the disease. In about one third of patients, SD is associated with systemic complications that can affect the joints, skin, lungs, kidneys, central or peripheral nervous system, and lymphoid organs with an increased risk of B-cell lymphoma. SD affects women more frequently than men (9/1). The peak frequency is around the age of 50. However, the disease can occur at any age, with paediatric forms occurring even though they remain rare. SD can occur alone or in association with other systemic autoimmune diseases. In its isolated or primary form, the prevalence of SD is estimated to be between 1 per 1000 and 1 per 10,000 inhabitants. The most recent classification criteria were developed in 2016 by EULAR and ACR. The course and prognosis of the disease are highly variable and depend on the presence of systemic involvement and the severity of the dryness of the eyes and mouth. The current approach is therefore to identify at an early stage those patients most at risk of systemic complications or lymphoma, who require close follow-up. On the other hand, regular monitoring of the ophthalmological damage and of the dental status should be ensured to reduce the consequences.

Satralizumab: A Review in Neuromyelitis Optica Spectrum Disorder

Satralizumab (Enspryng^®) is a monoclonal antibody that blocks the interleukin-6 (IL-6) receptor and is approved for the treatment of neuromyelitis optica spectrum disorder (NMOSD) in patients who are aquaporin-4 immunoglobulin G (AQP4-IgG) seropositive. Patients with NMOSD are at risk of recurrent autoimmune attacks that primarily target the optic nerves and spinal cord but may also target other regions of the central nervous system; these attacks can lead to life-long disability. In the randomized, placebo-controlled phase III SAkuraSky and SAkuraStar trials, subcutaneous satralizumab as an add-on to immunosuppressive therapy or as a monotherapy, respectively, significantly reduced the risk of relapse compared with placebo in patients who were AQP4-IgG seropositive with NMOSD. Satralizumab was well tolerated; the most common adverse events were infection, headache, arthralgia, decreased white blood cell count, hyperlipidaemia and injection-related reactions. In the EU, satralizumab is the first IL-6 receptor blocker to be approved for treatment of AQP4-IgG-seropositive patients with NMOSD, has the potential advantage of subcutaneous administration, and is the only targeted treatment approved for adolescent patients with this disorder. Thus, satralizumab is a valuable treatment option for patients with NMOSD.

Therapeutic Plasma Exchange in Certain Immune-Mediated Neurological Disorders: Focus on a Novel Nanomembrane-Based Technology

Therapeutic plasma exchange (TPE) is an efficient extracorporeal blood purification technique to remove circulating autoantibodies and other pathogenic substances. Its mechanism of action in immune-mediated neurological disorders includes immediate intravascular reduction of autoantibody concentration, pulsed induction of antibody redistribution, and subsequent immunomodulatory changes. Conventional TPE with 1 to 1.5 total plasma volume (TPV) exchange is a well-established treatment in Guillain-Barre Syndrome, Chronic Inflammatory Demyelinating Polyradiculoneuropathy, Neuromyelitis Optica Spectrum Disorder, Myasthenia Gravis and Multiple Sclerosis. There is insufficient evidence for the efficacy of so-called low volume plasma exchange (LVPE) (<1 TPV exchange) implemented either by the conventional or by a novel nanomembrane-based TPE in these neurological conditions, including their impact on conductivity and neuroregenerative recovery. In this narrative review, we focus on the role of nanomembrane-based technology as an alternative LVPE treatment option in these neurological conditions. Nanomembrane-based technology is a promising type of TPE, which seems to share the basic advantages of the conventional one, but probably with fewer adverse effects. It could play a valuable role in patient management by ameliorating neurological symptoms, improving disability, and reducing oxidative stress in a cost-effective way. Further research is needed to identify which patients benefit most from this novel TPE technology.

Anti-IL-6 therapies in central nervous system inflammatory demyelinating diseases

Current treatments for central nervous system (CNS) inflammatory demyelinating diseases (IDDs) include corticosteroids, plasma exchange, intravenous immunoglobulin, and immunosuppressant drugs. However, some patients do not respond well to traditional therapies. In recent years, novel drugs, such as monoclonal antibodies, targeting the complement component C5, CD19 on B cells, and the interleukin-6 (IL-6) receptor, have been used for the treatment of patients with refractory CNS IDDs. Among these, tocilizumab and satralizumab, humanized monoclonal antibodies against the IL-6 receptor, have shown beneficial effects in the treatment of this group of diseases. In this review, we summarize current research progress and prospects relating to anti-IL-6 therapies in CNS IDDs.

Treatment and Relapse Prevention of Typical and Atypical Optic Neuritis

Optic neuritis (ON) is an inflammatory condition involving the optic nerve. Several important typical and atypical ON variants are now recognized. Typical ON has a more favorable prognosis; it can be idiopathic or represent an early manifestation of demyelinating diseases, mostly multiple sclerosis (MS). The atypical spectrum includes entities such as antibody-driven ON associated with neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody disease (MOGAD), chronic/relapsing inflammatory optic neuropathy (CRION), and sarcoidosis-associated ON. Appropriate and timely diagnosis is essential to rapidly decide on the appropriate treatment, maximize visual recovery, and minimize recurrences. This review paper aims at presenting the currently available state-of-the-art treatment strategies for typical and atypical ON, both in the acute phase and in the long-term. Moreover, emerging therapeutic approaches and novel steps in the direction of achieving remyelination are discussed.

Rapid Discrimination of Neuromyelitis Optica Spectrum Disorder and Multiple Sclerosis Using Machine Learning on Infrared Spectra of Sera

Neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) are both autoimmune inflammatory and demyelinating diseases of the central nervous system. NMOSD is a highly disabling disease and rapid introduction of the appropriate treatment at the acute phase is crucial to prevent sequelae. Specific criteria were established in 2015 and provide keys to distinguish NMOSD and MS. One of the most reliable criteria for NMOSD diagnosis is detection in patient’s serum of an antibody that attacks the water channel aquaporin-4 (AQP-4). Another target in NMOSD is myelin oligodendrocyte glycoprotein (MOG), delineating a new spectrum of diseases called MOG-associated diseases. Lastly, patients with NMOSD can be negative for both AQP-4 and MOG antibodies. At disease onset, NMOSD symptoms are very similar to MS symptoms from a clinical and radiological perspective. Thus, at first episode, given the urgency of starting the anti-inflammatory treatment, there is an unmet need to differentiate NMOSD subtypes from MS. Here, we used Fourier transform infrared spectroscopy in combination with a machine learning algorithm with the aim of distinguishing the infrared signatures of sera of a first episode of NMOSD from those of a first episode of relapsing-remitting MS, as well as from those of healthy subjects and patients with chronic inflammatory demyelinating polyneuropathy. Our results showed that NMOSD patients were distinguished from MS patients and healthy subjects with a sensitivity of 100% and a specificity of 100%. We also discuss the distinction between the different NMOSD serostatuses. The coupling of infrared spectroscopy of sera to machine learning is a promising cost-effective, rapid and reliable differential diagnosis tool capable of helping to gain valuable time in patients’ treatment.

Comparative study of AQP4-NMOSD, MOGAD and seronegative NMOSD: a single-center Belgian cohort

Purpose

To emphasize physio-pathological, clinical and prognosis differences between conditions causing serious and sometimes very similar clinical manifestations: anti-aquaporin-4 (AQP4) and anti-myelin oligodendrocyte glycoprotein (MOG) antibodies related diseases, and seronegative NMOSD (neuromyelitis optica spectrum disorders).

Methods

Based on Wingerchuk et al. (Neurology 85:177–189, 2015) criteria for NMOSD and on those more recently proposed by Jarius et al. (J Neuroinflammation 15:134, 2018) for MOGAD (MOG associated disorders), we retrospectively surveyed 10 AQP4-NMOSD, 8 MOGAD and 2 seronegative NMOSD, followed at the specialized neuroimmunology unit of the CHU Liège.

Results

Female predominance was only observed in AQP4 group. Age at onset was 37.8 and 27.7 years old for AQP4-NMOSD and MOGAD respectively. In both groups, the first clinical event most often consisted of optic neuritis (ON), followed by isolated myelitis. Fifteen of our 20 patients encountered a relapsing course with 90% relapses in AQP4-NMOSD, 62.5% in MOGAD and 50% in seronegative group, and a mean period between first and second clinical event of 7.1 and 4.8 months for AQP4-NMOSD and MOGAD, respectively. In total we counted 54 ON, with more ON per patient in MOGAD. MOG-associated ON mainly affected the anterior part of the optic nerve with a papilledema in 79.2% of cases. Despite a fairly good visual outcome after MOG-associated ON, retinal nerve fibre layer (RNFL) thickness decreased, suggesting a fragility of the optic nerve toward further attacks.

Conclusion

As observed in larger cohorts, our MOGAD and AQP4-NMOSD cases differ by clinical and prognostic features. A better understanding of these diseases should encourage prompt biological screening and hasten proper diagnosis and treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13760-021-01712-3.

What's new in neuromyelitis optica spectrum disorder treatment?

Optic neuritis, an optic nerve inflammatory disease presenting with acute unilateral or bilateral visual loss, is one of the core symptoms of neuromyelitis optica spectrum disorder (NMOSD). The diagnosis of NMOSD-related optic neuritis is challenging, and it is mainly based on clinical presentation, optical coherence tomography, magnetic resonance imaging scans, and the status of serum aquaporin-4 antibodies. In the pathogenesis, aquaporin-4 antibodies target astrocytes in the optic nerves, spinal cord and some specific regions of the brain eliciting a devastating autoimmune response. Current pharmacological interventions are directed against various steps within the immunological response, notably the terminal complement system, B-cells, and the pro-inflammatory cytokine Interleukin 6 (IL6). Conventional maintenance therapies were off-label uses of the unspecific immunosuppressants azathioprine and mycophenolate mofetil as well as the CD20 specific antibody rituximab and the IL6 receptor specific antibody tocilizumab. Recently, four phase III clinical trials demonstrated the safety and efficacy of the three novel biologics eculizumab, inebilizumab, and satralizumab. These monoclonal antibodies are directed against the complement system, CD19 B-cells and the IL6 receptor, respectively. All three have been approved for NMOSD in the US and several other countries worldwide and thus provide convincing treatment options.

MRI Patterns Distinguish AQP4 Antibody Positive Neuromyelitis Optica Spectrum Disorder From Multiple Sclerosis

Neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) are inflammatory diseases of the CNS. Overlap in the clinical and MRI features of NMOSD and MS means that distinguishing these conditions can be difficult. With the aim of evaluating the diagnostic utility of MRI features in distinguishing NMOSD from MS, we have conducted a cross-sectional analysis of imaging data and developed predictive models to distinguish the two conditions. NMOSD and MS MRI lesions were identified and defined through a literature search. Aquaporin-4 (AQP4) antibody positive NMOSD cases and age- and sex-matched MS cases were collected. MRI of orbits, brain and spine were reported by at least two blinded reviewers. MRI brain or spine was available for 166/168 (99%) of cases. Longitudinally extensive (OR = 203), "bright spotty" (OR = 93.8), whole (axial; OR = 57.8) or gadolinium (Gd) enhancing (OR = 28.6) spinal cord lesions, bilateral (OR = 31.3) or Gd-enhancing (OR = 15.4) optic nerve lesions, and nucleus tractus solitarius (OR = 19.2), periaqueductal (OR = 16.8) or hypothalamic (OR = 7.2) brain lesions were associated with NMOSD. Ovoid (OR = 0.029), Dawson's fingers (OR = 0.031), pyramidal corpus callosum (OR = 0.058), periventricular (OR = 0.136), temporal lobe (OR = 0.137) and T1 black holes (OR = 0.154) brain lesions were associated with MS. A score-based algorithm and a decision tree determined by machine learning accurately predicted more than 85% of both diagnoses using first available imaging alone. We have confirmed NMOSD and MS specific MRI features and combined these in predictive models that can accurately identify more than 85% of cases as either AQP4 seropositive NMOSD or MS.

Treatment options in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorders

There are few diseases with as many therapeutic advances in recent years as in multiple sclerosis. Nine different drug classes with more than a dozen approved therapies are now available. Similarly, there have been unimaginable advances in understanding neuromyelitis optica (now neuromyelitis optica spectrum disorder [NMOSD]) over the past 15 years. Building on the knowledge gained, the first therapies have been approved in recent years. In this review, we aim to present all therapies approved for the treatment of MS or NMOSD. The different forms of application, different approval criteria and most important side effects will be presented. This work is intended for physicians who are interested in MS and NMOSD therapies and want to get a first overview and does not replace the respective guidelines of the regulatory authorities.

Neuromyelitis optica, aquaporin-4 antibodies, and neuroendocrine disorders

Neuromyelitis optica (NMO) is an autoimmune disorder of the central nervous system that preferentially affects the optic nerve and the spinal cord. In around 80% of NMO patients, autoantibodies binding to aquaporin-4 (AQP4) are detected. AQP4-IgG unifies a spectrum of disorders (NMOSD) that include not only optic neuritis, longitudinally extensive transverse myelitis but also syndromes caused by lesion of the diencephalic region and the circumventricular organs (CVOs). The distinctive immunopathological characteristics of NMOSD lesions, occurring in regions where AQP4 is highly expressed, supports a central role for AQP4-IgG in disease pathogenesis. AQP4 expression is concentrated in CVOs and in the hypothalamus, mainly in the dorsal hypothalamic area, dorsomedial hypothalamic nucleus and suprachiasmatic nucleus. Several neuroendocrine disorders caused by inflammatory lesions involving the diencephalic region have been described in patients with NMOSD, including syndrome of inappropriate antidiuresis, sleep disorders, and other endocrinopathies caused by hypothalamic injury. Focus of this chapter is the involvement of hypothalamus and CVOs in AQP4 autoimmunity.

Satralizumab: First Approval

Satralizumab (Enspryng^®), a humanized anti-interleukin-6 (IL-6) receptor monoclonal recycling antibody, has been developed by Chugai Pharmaceutical and Roche for the treatment of neuromyelitis optica spectrum disorder (NMOSD). In June 2020, based on positive results from two pivotal phase III trials, subcutaneous satralizumab received its first global approval in Canada for the treatment of NMOSD in adults and children aged ≥ 12 years who are aquaporin 4 water channel autoantibody (AQP4-IgG) seropositive. Satralizumab was subsequently approved in Japan, Switzerland and the USA. Satralizumab is under regulatory review in the EU, and is undergoing clinical development in several countries worldwide. This article summarizes the milestones in the development of satralizumab leading to this first approval for the treatment of NMOSD.

Eculizumab in the Treatment of Aquaporin-4 Seronegative Neuromyelitis Optica Spectrum Disorder: A Case Report

Objective: To report the case of a 35-year-old woman with treatment-resistant aquaporin-4 (AQP-4) immunoglobulin G (IgG) seronegative neuromyelitis optica spectrum disorder (NMOSD) successfully treated with eculizumab (a terminal complement inhibitor).

Methods: The investigational procedures and treatment regimens the patient received were documented over 8 years [2012 (first presentation) to 2020].

Results: The patient presented with subacute onset of lower-limb weakness and numbness, gait imbalance, and urinary incontinence. Magnetic resonance imaging (MRI) showed abnormalities in the thoracic spine from T7 to T10, but brain and cervical spine scans, visual evoked potential latencies, and IgG index were normal; cerebrospinal fluid pleocytosis and oligoclonal bands were both present. After treatment with intravenous methylprednisolone 1 g/day for 5 days, the patient was discharged without medication to acute rehabilitation but experienced relapses from 2012 to 2014. She was treated with oral prednisone (initiated at 40 mg/day in 2014; the dose was halved in 2015 due to weight gain) and mycophenolate mofetil (MMF) 1 g twice daily (from June 2015), but between 2014 and 2019 experienced 4–5 relapses/year, requiring treatment with intravenous methylprednisolone, with added maintenance plasma exchange from 2018 onwards. Although the patient tested negative for antibodies to AQP-4 and myelin oligodendrocyte glycoprotein, she was diagnosed with NMOSD in February 2017, based on recurrent episodes of longitudinal extensive transverse myelitis, MRI changes, and area postrema syndrome. By 2018 the patient needed a cane to walk. Prednisone and MMF were discontinued mid-2018, and rituximab was prescribed from July 2018 (maintenance regimen two 1 g doses 2 weeks apart every 6 months) but discontinued in July 2019 owing to lack of significant improvement. From July 2019 eculizumab was prescribed for 6 months (900 mg weekly for the first four doses, then 1200 mg every 2 weeks). The patient had no relapses or adverse events during and after eculizumab treatment (as of August 2020) and was able to walk unaided; her Expanded Disability Status Scale score improved from 4–5 during 2015–2018 to 2 in 2020 following eculizumab treatment.

Conclusion: Eculizumab shows promise as a treatment for AQP-4 IgG-seronegative NMOSD and further studies are warranted.

Persistently Gadolinium-Enhancing Lesion Is a Predictor of Poor Prognosis in NMOSD Attack: a Clinical Trial

Gadolinium (Gd)-contrast MRI for reliable detection of blood-brain barrier (BBB) breakdown is widely used in neuromyelitis optica spectrum disorder (NMOSD) attack. Nonetheless, little is known about the predictive role of gadolinium-enhancing lesion in prognosis of NMOSD attack. The aim of this work is to investigate the predictive value of persistently Gd-enhanced lesions to medium-term outcome after attack. Data for this analysis came from an ongoing prospective cohort study (CLUE). NMOSD patients with acute attack were enrolled from January 2019 to March 2020. All patients underwent Gd-contrast MRI at baseline and 1 month, and disability was assessed by Expanded Disability Status Scale (EDSS). Primary outcome was EDSS improvement from baseline to month 6. Multiple logistic regression identified predictors for poor recovery of NMOSD attack. Forty-one participants were analyzed, of which 21 patients had persistently Gd-enhancing lesions. Patients in no enhancement (NE) group showed a significant shift in 6-month EDSS distributions compared with those in persistent enhancement (PE) group (p = 0.005). Poor recovery rate of the PE group was higher than that of the NE group at 6 months (p = 0.033). In patients with aquaporin-4-positive, first-attack, transverse myelitis or in a high-dose steroid treatment subgroup, the improvement of EDSS scores in the PE group was still less compared with that in the NE group (p < 0.05). The presence of persistently Gd-enhancing lesion appears to be associated with poor recovery after attack (OR = 5.473, p = 0.014). Our study found that persistently gadolinium-enhancing lesion is a poor prognosis predictor after NMOSD attack. Trial registration ID: NCT04106830.

Targeting interleukin-6 to treat neuromyelitis optica spectrum disorders: Implications from immunology, the FcRn pathway and clinical experience

Neuromyelitis optica spectrum disorder (NMOSD) is a rare disease of the central nervous system (CNS) that is associated with poor outcomes for patients. Until recently, when complement inhibitors were approved, there was no approved therapy. Most recently, clinical trials of interleukin-6 (IL-6) blockade showed a therapeutic benefit for NMOSD. In this review, we introduce the immunological basis of IL-6 blockade in NMOSD and summarize current knowledge about the clinical use of the IL-6 receptor inhibitors tocilizumab and satralizumab. The aim of extending the half-life of monoclonal antibodies (mAbs) has been actualized by successful clinical translation for Satralizumab, achieved via the neonatal Fc receptor (FcRn) pathway. The basic principles of FcRn are highlighted in this review together with the potential therapeutic benefits of this emerging technology.

Neuromyelitis Optica Spectrum Disorder Treatment-Current and Future Prospects

Neuromyelitis optica (NMO) is an immune-mediated demyelinative disorder of the central nervous system affecting mainly the optical nerves and the spinal cord. The recurrent course of the disease, with exacerbations and incomplete remissions, causes accumulating disability, which has a profound impact upon patients’ quality of life. The discovery of antibodies against aquaporin 4 (AQP4) and their leading role in NMO etiology and the formulation of diagnostic criteria have improved appropriate recognition of the disease. In recent years, there has been rapid progress in understanding the background of NMO, leading to an increasing range of treatment options. On the basis of a review of the relevant literature, the authors present currently available therapeutic strategies for NMO as well as ongoing research in this field, with reference to key points of immune-mediated processes involved in the background of the disease.

Targeting the complement system in neuromyelitis optica spectrum disorder

INTRODUCTION

Neuromyelitis optica spectrum disorder (NMOSD) is characterized by central nervous system inflammation and demyelination. In AQP4-IgG seropositive NMOSD, circulating immunoglobulin G (IgG) autoantibodies against astrocyte water channel aquaporin-4 (AQP4) cause tissue injury. Compelling evidence supports a pathogenic role for complement activation following AQP4-IgG binding to AQP4. Clinical studies supported the approval of eculizumab, an inhibitor of C5 cleavage, in AQP4-IgG seropositive NMOSD.

AREAS COVERED

This review covers in vitro, animal models, and human evidence for complement-dependent and complement-independent tissue injury in AQP4-IgG seropositive NMOSD. Complement targets are discussed, including complement proteins, regulators and anaphylatoxin receptors, and corresponding drug candidates.

EXPERT OPINION

Though preclinical data support a central pathogenic role of complement activation in AQP4-IgG seropositive NMOSD, they do not resolve the relative contributions of complement-dependent vs. complement-independent disease mechanisms such as antibody-dependent cellular cytotoxicity, T cell effector mechanisms, and direct AQP4-IgG-induced cellular injury. The best evidence that complement-dependent mechanisms predominate in AQP4-IgG seropositive NMOSD comes from eculizumab clinical data. Various drug candidates targeting distinct complement effector mechanisms may offer improved safety and efficacy. However, notwithstanding the demonstrated efficacy of complement inhibition in AQP4-IgG seropositive NMOSD, the ultimate niche for complement inhibition is not clear given multiple drug options with alternative mechanisms of action.Abbreviations: AAV2, Adeno-associated virus 2; ADCC, antibody-dependent cellular cytotoxicity; ANCA, antineutrophilic cytoplasmic autoantibody; AQP4, aquaporin-4; AQP4-IgG, AQP4-immunoglobulin G; C1-INH, C1-esterase inhibitor; C3aR, C3a receptor; C4BP, C4 binding protein; C5aR, C5a receptor; CDC, complement-dependent cytotoxicity; CFHR1, complement factor H related 1; CNS, central nervous system; EAE, experimental autoimmune encephalomyelitis; EndoS, endoglycosidase S; FHL-1, factor-H-like protein 1; GFAP, glial fibrillary acidic protein; Iba-1, ionized calcium-binding adaptor protein-1; IgG, immunoglobulin G; IVIG, intravenous human immunoglobulin G; MAC, membrane attack complex; MBL, maltose-binding lectin; MBP, myelin basic protein; MOG, myelin oligodendrocyte glycoprotein; NK cell, natural killer cell; NMOSD, neuromyelitis optica spectrum disorder; OAP, orthogonal arrays of particles; PNH, paroxysmal nocturnal hemoglobinuria.

Efficacy of rituximab in the treatment of neuromyelitis optica spectrum disorders: An update systematic review and meta -analysis

BACKGROUND

Neuromyelitis optica spectrum disorders (NMOSD) is an autoimmune astrocyte disease that mainly affects the optic nerve and spinal cord resulting in blindness or paralysis. Rituximab (RTX) is a chimeric monoclonal antibody directed against the surface antigen of CD20 on B lymphocytes and is an emerging treatment option in NMOSD. The present review aimed to conduct an update systematic review and meta-analysis for the efficacy of RTX in the treatment of NMOSD and analyze main factors affecting the efficacy of RTX.

METHODS

The following Medical Subject Heading (MeSH) and related entry terms are used to search English literature in PubMed, MEDLINE and CENTRAL databases, respectively. MeSH include: Neuromyelitis optic and Rituximab; entry terms include: NMO Spectrum Disorder, NMO Spectrum Disorders, Neuromyelitis Optica (NMO) Spectrum Disorder, Neuromyelitis Optica Spectrum Disorders, Devic Neuromyelitis Optica, Neuromyelitis Optica, Devic, Devic's Disease, Devic Syndrome, Devic's Neuromyelitis Optica, Neuromyelitis Optica (NMO) Spectrum Disorders, CD20 Antibody, Rituximab CD20 Antibody, Mabthera, IDEC-C2B8 Antibody, GP2013, Rituxan; (note: literature retrieval operators "AND" "OR" "NOT" are used to link MeSH with Entry Terms.) 54 studies were included in this systematic review and 29 studies were included in meta-analysis. The main efficacy indicators were the difference of the expanded disability status scale (EDSS) and annualized relapse rate (ARR) between before and after rituximab treatments.

RESULTS

In 29 studies involving 732 patients (643 women, 84 men, 5 with unknown gender), the EDSS and ARR were reduced by an average of -0.57 (95%CI, -0.69 to -0.44), -1.57 (95%CI, -1.78 to -1.35), respectively.

CONCLUSION

Our systematic review and update meta-analysis provide new evidences that RTX can effectively improve disability and reduce ARR ratio.

Anti-IL-6 Therapies for Neuromyelitis Optica Spectrum Disorders: A Systematic Review of Safety and Efficacy

BACKGROUND

Neuromyelitis Optica Spectrum Disorder (NMOSD) is a chronic autoimmune disease of the central nervous system that causes recurrent attacks of optic neuritis, myelitis, and brainstem symptoms, resulting in severe neurological disability. Preventive treatment with immunosuppressive agents reduces relapse rate and improves long-term prognosis. In recent years, the potential therapeutical effect of new agents has been investigated. Two of these, the anti-interleukin 6 (IL-6) agents tocilizumab and satralizumab, have been studied in active NMOSD.

OBJECTIVE

To systematically review the current data regarding the efficacy and safety of anti-IL-6 agents in NMOSD.

RESULTS

Fourteen case reports and 5 case series of intravenous tocilizumab have shown beneficial clinical and paraclinical effects compared to commonly used therapies, and another case series of subcutaneous tocilizumab has shown it is as effective as the IV formulation. A phase 2 comparative trial has shown tocilizumab IV to be more effective than azathioprine for relapse prevention. A phase 3 trial of subcutaneous satralizumab versus placebo, has shown a lower risk of relapse in the sartralizumab-treated group, both as add-on therapy to stable immunosuppressant and as monotherapy. Tocilizumab also reduced pain severity in two trials and fatigue scores in one trial, but satralizumab did not significantly improve pain and fatigue. Adverse events with both agents were relatively mild and comparable to placebo and azathioprine.

CONCLUSION

The anti-Il-6 agents tocilizumab and satralizumab show promising results in active NMOSD. Further randomized, larger-scale trials are needed to better define the role of these agents in the growing arsenal of NMOSD treatments.

Eculizumab: A Review in Neuromyelitis Optica Spectrum Disorder

The terminal complement protein (C5) inhibitor eculizumab (Soliris^®) is the first agent to be specifically approved in the EU, USA, Canada and Japan for the treatment of neuromyelitis optica spectrum disorder (NMOSD) in adults who are aquaporin-4 water channel autoantibody (AQP4-IgG) seropositive and (in the EU only) for those with a relapsing course of disease. In the phase III PREVENT trial, eculizumab significantly reduced the risk of adjudicated relapse relative to placebo in patients with AQP4-IgG-seropositive NMOSD, approximately a quarter of whom did not receive concomitant immunosuppressive therapies. The beneficial effect of eculizumab was seen across all patient subgroups analysed and was accompanied by improvements in neurological and functional disability assessments, as well as generic health-related quality of life measures; it was sustained through 4 years of treatment, according to combined data from the PREVENT trial and an interim analysis of its ongoing open-label extension study. The safety profile of eculizumab in AQP4-IgG-seropositive NMOSD was consistent with that seen for the drug in other approved indications. Thus, eculizumab provides an effective, generally well tolerated and approved treatment option for this rare, disabling and potentially life-threatening condition.

Different Targets of Monoclonal Antibodies in Neuromyelitis Optica Spectrum Disorders: A Meta-Analysis Evidenced From Randomized Controlled Trials

Background: Neuromyelitis optica spectrum disorder (NMOSD), an autoimmune inflammatory disorder of the central nervous system, often leads to vision loss or paralysis. This meta-analysis focused on the assessment of the monoclonal antibody therapy in NMOSD and compared different targets of monoclonal antibodies with each other in terms of efficacy and safety outcomes.

Method: We searched through the databases of MEDLINE, EMBASE, Central Register of Controlled Trials (CENTRAL), and clinicaltrials.gov for randomized controlled trials (RCTs) evaluating monoclonal antibody therapy in NMOSD up to April 2020.

Results: We identified seven randomized controlled trials (RCTs), including 775 patients (monoclonal antibody group, n = 485 and placebo group, n = 290). Monoclonal antibody therapy decreased relapse risk (RR 0.33, 95% CI 0.21–0.52, P < 0.00001), annualized relapse rate (ARR) (mean −0.28, 95% CI −0.35−0.20, P < 0.00001), expanded disability status scale score (EDSS) (mean −0.19, 95% CI −0.32−0.07, P = 0.002) and serious adverse events (RR 0.78, 95% CI 0.61–1.00, P = 0.05). However, we did not observe any significant difference in terms of adverse events or mortality. Further, the subgroup analysis demonstrated that the anti-complement protein C5 monoclonal antibody (eculizumab) might have a lower relapse risk (RR 0.07, 95% CI 0.02–0.23, P < 0.0001) in the AQP4 seropositive patients, and anti-interleukin-6 receptor monoclonal antibodies (satralizumab and tocilizumab) showed decreased EDSS score (mean −0.17, 95% CI −0.31−0.02, P = 0.02) more effectively than other monoclonal antibodies.

Conclusions: Monoclonal antibodies were effective and safe in NMOSD. Different targets of monoclonal antibodies might have their own advantages.

Clinical and Radiological Characteristics of Neuromyelitis Optica Spectrum Disorder: The Experience from Saudi Arabia

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune astrocytopathy that affects several regions of the central nervous system (CNS) with a predilection for the optic nerves and spinal cord. Epidemiological studies of NMOSD are uncommon in the Middle East and up-to-date, there are no such data from Saudi Arabia. In this study, we aim to study the clinical pattern of NMOSD patients in Saudi Arabia.

METHODS

A retrospective multi-center observational study was conducted at King Abdulaziz Medical City in Jeddah and Riyadh, Saudi Arabia. The inclusion criteria consisted of all the patients with either neuromyelitis optica according to the 2006 criteria or NMOSD according to the 2015 criteria. The study period was 20 years.

RESULTS

A total of 23 patients were included in the study. Four were males (17.4%) and 19 were females (82.6%). The attack type was optic neuritis in 3 patients (13.0%), transverse myelitis in 15 patients (65.2%), and both in 5 patients (21.7%). All patients (100%) received pulse steroid therapy (intravenous methylprednisolone 1 g for 5 days) at the onset of the disease. Fifteen patients had plasma exchange therapy (65.2%). All patients received maintenance immunosuppressive treatment except 1 (4.3%).

CONCLUSION

NMOSD is a rare, broad-spectrum, polyphasic, rare disorder primarily affecting the optic pathway and the spinal cord either in isolation or simultaneously. Unfortunately, there are no adequate studies that assess NMOSD cohorts in Saudi Arabia despite the increased number of diagnosed cases. In addition, there is no registry for this disorder with only a few specialized centers dealing with its management. It is time to establish specialized demyelinating disease centers and build expertise in both common and rare diseases in this category.

Satralizumab for the Treatment of Neuromyelitis Optica Spectrum Disorders

OBJECTIVE

To review the pharmacological characteristics, clinical evidence, and place in therapy of satralizumab for the treatment of neuromyelitis optica spectrum disorders (NMOSDs).

DATA SOURCES

A comprehensive literature search was conducted in PubMed (January 2000 to October 15, 2020). Key search terms included satralizumab and neuromyelitis optica spectrum disorders. Other sources were derived from product labeling and ClinicalTrials.gov.

STUDY SELECTION AND DATA EXTRACTION

All English-language articles identified from the data sources were reviewed and evaluated. Phase I, II, and III clinical trials were included.

DATA SYNTHESIS

NMOSD is an autoimmune disease characterized by inflammatory lesions in the optic nerves and spinal cord. Interleukin-6 is involved in the pathogenesis of the disorder. Satralizumab is a humanized monoclonal antibody targeting the interleukin-6 receptor. Phase III trials showed that protocol-defined relapse was 30% for satralizumab and 50% for placebo (P = 0.018) when patients with NMOSD were treated with satralizumab monotherapy; protocol-defined relapse was 20% for satralizumab and 43% for placebo (P = 0.02) when satralizumab was added to immunosuppressant treatment. Satralizumab is generally well tolerated, with common adverse effects including injection-related reaction.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Satralizumab has the potential to become a valuable treatment option for patients with NMOSD.

CONCLUSION

Satralizumab appears to be safe and effective as monotherapy or in combination with an immunosuppressant for patients with NMOSD and has the potential to become a valuable treatment option for these patients.

Precision Medicine in Neurology: The Inspirational Paradigm of Complement Therapeutics

Precision medicine has emerged as a central element of healthcare science. Complement, a component of innate immunity known for centuries, has been implicated in the pathophysiology of numerous incurable neurological diseases, emerging as a potential therapeutic target and predictive biomarker. In parallel, the innovative application of the first complement inhibitor in clinical practice as an approved treatment of myasthenia gravis (MG) and neuromyelitis optica spectrum disorders (NMOSD) related with specific antibodies raised hope for the implementation of personalized therapies in detrimental neurological diseases. A thorough literature search was conducted through May 2020 at MEDLINE, EMBASE, Cochrane Library and ClinicalTrials.gov databases based on medical terms (MeSH)" complement system proteins" and "neurologic disease". Complement's role in pathophysiology, monitoring of disease activity and therapy has been investigated in MG, multiple sclerosis, NMOSD, spinal muscular atrophy, amyotrophic lateral sclerosis, Parkinson, Alzheimer, Huntington disease, Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, stroke, and epilepsy. Given the complexity of complement diagnostics and therapeutics, this state-of-the-art review aims to provide a brief description of the complement system for the neurologist, an overview of novel complement inhibitors and updates of complement studies in a wide range of neurological disorders.

Complement in neurological disorders and emerging complement-targeted therapeutics

The complement system consists of a network of plasma and membrane proteins that modulate tissue homeostasis and contribute to immune surveillance by interacting with the innate and adaptive immune systems. Dysregulation, impairment or inadvertent activation of complement components contribute to the pathogenesis of some autoimmune neurological disorders and could even contribute to neurodegenerative diseases. In this Review, we summarize current knowledge about the main functions of the complement pathways and the involvement of complement in neurological disorders. We describe the complex network of complement proteins that target muscle, the neuromuscular junction, peripheral nerves, the spinal cord or the brain and discuss the autoimmune mechanisms of complement-mediated myopathies, myasthenia, peripheral neuropathies, neuromyelitis and other CNS disorders. We also consider the emerging role of complement in some neurodegenerative diseases, such as Alzheimer disease, amyotrophic lateral sclerosis and even schizophrenia. Finally, we provide an overview of the latest complement-targeted immunotherapies including monoclonal antibodies, fusion proteins and peptidomimetics that have been approved, that are undergoing phase I–III clinical trials or that show promise for the treatment of neurological conditions that respond poorly to existing immunotherapies.

In this Review, Dalakas et al. discuss the complement system, the role it plays in autoimmune neurological disease and neurodegenerative disease, and provide an overview of the latest therapeutics that target complement and that can be used for or have potential in neurological disorders.

Complement has an important physiological role in host immune defences and tissue remodelling.

The physiological role of complement extends to the regulation of synaptic development.

Complement has a key pathophysiological role in autoimmune neurological diseases and mediates the actions of pathogenic autoantibodies, such as acetylcholine receptor antibodies and aquaporin 4 antibodies.

For some autoimmune neurological diseases, such as myasthenia gravis and neuromyelitis optica spectrum disorders, approved complement-targeted treatments are now available.

Complement also seems to be of pathogenic relevance in neurodegenerative diseases such as Alzheimer disease, in which innate immune-driven inflammation is receiving increasing attention.

The field of complement-targeted therapeutics is rapidly expanding, with several FDA-approved agents and others currently in phase II and phase III clinical trials.

Risk of relapse in patients with neuromyelitis optica spectrum disorder: Recognition and preventive strategy

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune inflammatory disorder of the central nervous system (CNS) that is mainly associated with serum autoantibodies against aquaporin-4 (AQP4) in astrocytes. The relapsing clinical course of NMOSD, which can be blinding and disabling due to severe visual impairment, spinal cord lesions and a group of brain syndromes, suggests the importance of accurately evaluating the likelihood and severity of relapse at an early stage of the disease. To date, many risk factors have been revealed in association with relapse, and only some of them are supported by substantial evidence. Furthermore, while the clinical use of conventional immunosuppressants is mostly empirical, an increasing number of emerging therapies for monoclonal antibodies have been confirmed by several randomized placebo-controlled trials to be effective and safe for relapse prevention. In this review, we summarize the reported risk factors that may influence the frequency, symptoms, severity and prognosis of relapse in NMOSD, as well as the efficacy and safety of emerging therapies for relapse prevention. All of these results enable us to better recognize patients who are at higher risk of relapse and suggest more effective monoclonal antibody therapies for use in these patients.

Emerging drugs for the treatment of neuromyelitis optica

INTRODUCTION

Evidence-based treatment options for neuromyelitis optica spectrum disorders (NMOSD) patients are beginning to enter the market. Where previously, there was only the exclusive use of empiric and off-label immunosuppressants in this rare and devastating central nervous system autoimmune disease.

AREAS COVERED

In accordance to expanding pathogenetic insights, drugs in phase II and III clinical trials are presented in the context of the current treatment situation for acute attacks and immunopreventative strategies in NMOSD. Some such drugs are the 2019-approved complement inhibitor eculizumab, other compounds in late development include its modified successor ravulizumab, IL-6 receptor antibody satralizumab, CD19 targeting antibody inebilizumab and the TACI-Fc fusion protein telitacicept.

EXPERT OPINION

Moving from broad immunosuppression to tailored treatment strategies, the prospects for efficient NMOSD therapy are positive. For the first time in this disease, class I treatment evidence is available, but long-term data will be necessary to confirm the overall promising study results of the compounds close to approval. While drug development still centers around AQP4 antibody seropositive patients, current and future research requires consideration of possible diverging treatment demands for the smaller group of seronegative patients and patients with presence of MOG antibodies.

Autoimmune and demyelinating optic neuritis

The knowledge on demyelinating and autoimmune optic neuropathies has experienced a revolution the last decade since the discovery of anti-aquaporin 4 antibody. Improvements in diagnostic techniques, and the finding of new targets, along with advances in neuro-immunology have led to the detection of antibodies related to demyelinating diseases. A review is presented on the classical and new concepts in optic neuritis. The debate on the classification of demyelinating and autoimmune optic neuritis is presented. Furthermore, the updated diagnostic criteria in multiple sclerosis and neuro-myelitis optics are described. Finally, the latest insights into Myelin Oligodendrocyte Glycoprotein (MOG) disorders and chronic-recurring optic neuropathies (CRION) are highlited.

Safety and efficacy of tocilizumab versus azathioprine in highly relapsing neuromyelitis optica spectrum disorder (TANGO): an open-label, multicentre, randomised, phase 2 trial

BACKGROUND

Azathioprine is used as a first-line treatment to prevent relapses of neuromyelitis optica spectrum disorder (NMOSD). Tocilizumab has been reported to reduce NMOSD disease activity in retrospective case reports. We aimed to compare the safety and efficacy of tocilizumab and azathioprine in patients with highly relapsing NMOSD.

METHODS

We did an open-label, multicentre, randomised, phase 2 trial at six hospitals in China. We recruited adult patients (aged ≥18 years) with highly relapsing NMOSD diagnosed according to 2015 International Panel for Neuromyelitis Optica Diagnosis criteria, who had an Expanded Disability Status Scale (EDSS) score of 7·5 or lower, and had a history of at least two clinical relapses during the previous 12 months or three relapses during the previous 24 months with at least one relapse within the previous 12 months. Patients were randomly assigned (1:1) to intravenous tocilizumab (8 mg/kg every 4 weeks) or oral azathioprine (2-3 mg/kg per day) by an independent statistician using computer-generated randomisation software with permuted blocks of four. The central review committee, EDSS raters, laboratory personnel, and radiologists were masked to the treatment assignment, but investigators and patients were aware of treatment allocation. The minimum planned duration of treatment was 60 weeks following randomisation. The primary outcome was time to first relapse in the full analysis set, which included all randomly assigned patients who received at least one dose of study drug, and the per-protocol population, which included all patients who used azathioprine or tocilizumab as monotherapy. For the analyses of the primary outcome, the patients were prespecified into two subgroups according to concomitant autoimmune disease status. Safety was assessed in the full analysis set. This study is registered with ClinicalTrials.gov, NCT03350633.

FINDINGS

Between Nov 1, 2017, and Aug 3, 2018, we enrolled 118 patients, of whom 59 were randomly assigned to tocilizumab and 59 were randomly assigned to azathioprine. All 118 patients received one dose of study drug and were included in the full analysis set. 108 participants were included in the per-protocol analysis (56 in the tocilizumab group and 52 in the azathioprine group). In the full analysis set, median time to the first relapse was longer in the tocilizumab group than the azathioprine group (78·9 weeks [IQR 58·3-90·6] vs 56·7 [32·9-81·7] weeks; p=0·0026). Eight (14%) of 59 patients in the tocilizumab group and 28 (47%) of 59 patients in the azathioprine group had a relapse at the end of the study (hazard ratio [HR] 0·236 [95% CI 0·107-0·518]; p<0·0001). In the per-protocol analysis, 50 (89%) of 56 patients in the tocilizumab group were relapse-free compared with 29 (56%) of 52 patients in the azathioprine group at the end of the study (HR 0·188 [95% CI 0·076-0·463]; p<0·0001); the median time to first relapse was also longer in the tocilizumab group than the azathioprine group (67·2 weeks [IQR 47·9-77·9] vs 38·0 [23·6-64·9]; p<0·0001). In the prespecified subgroup analysis of the full analysis set stratified by concomitant autoimmune diseases, among patients without concomitant autoimmune diseases, three (9%) of 34 patients in the tocilizumab group and 13 (35%) of 37 patients in the azathioprine group had relapsed by the end of the study. Among patients with concomitant autoimmune diseases, a lower proportion of patients in the tocilizumab group had a relapse than in the azathioprine group (five [20%] of 25 patients vs 15 [68%] of 22 patients; HR 0·192 [95% CI 0·070-0·531]; p=0·0004). 57 (97%) of 59 patients in the tocilizumab group and 56 (95%) of 59 patients in the azathioprine group had adverse events. Treatment-associated adverse events occurred in 36 (61%) of 59 tocilizumab-treated patients and 49 (83%) of 59 azathioprine-treated patients. One death (2%) occurred in the tocilizumab group and one (2%) in the azathioprine group, but neither of the deaths were treatment-related.

INTERPRETATION

Tocilizumab significantly reduced the risk of a subsequent NMOSD relapse compared with azathioprine. Tocilizumab might therefore be another safe and effective treatment to prevent relapses in patients with NMOSD.

FUNDING

Tianjin Medical University, Advanced Innovation Center for Human Brain Protection, National Key Research and Development Program of China, National Science Foundation of China.

Neuromyelitis optica practice and prescribing changes in the setting of Covid19: A survey of neurologists

PURPOSE

This study reports and analyzes the findings from the responses of 192 neurologists in the United States and Canada to a new survey instrument distributed in April 2020 to assess NMO practice and prescribing changes during the Covid19 pandemic.

PRINCIPAL RESULTS

92% of responding neurologists considered their NMO patients to be at an elevated risk of acquiring Covid19. They also indicated sharp declines in visits, delays in treatment and related services, and several unmet needs deterring treatment.

MAJOR CONCLUSIONS

There is a need for evidence-based, comprehensive guidelines for treating NMO patients amid healthcare crises moving forward.

Complementopathies and precision medicine

The renaissance of complement diagnostics and therapeutics has introduced precision medicine into a widened field of complement-mediated diseases. In particular, complement-mediated diseases (or complementopathies) with ongoing or published clinical trials of complement inhibitors include paroxysmal nocturnal hemoglobinuria, cold agglutinin disease, hemolytic uremic syndrome, nephropathies, HELLP syndrome, transplant-associated thrombotic microangiopathy, antiphospholipid antibody syndrome, myasthenia gravis, and neuromyelitis optica. Recognizing that this field is rapidly expanding, we aim to provide a state-of-the-art review of (a) current understanding of complement biology for the clinician, (b) novel insights into complement with potential applicability to clinical practice, (c) complement in disease across various disciplines (hematology, nephrology, obstetrics, transplantation, rheumatology, and neurology), and (d) the potential future of precision medicine. Better understanding of complement diagnostics and therapeutics will not only facilitate physicians treating patients in clinical practice but also provide the basis for future research toward precision medicine in this field.

Natural killer cells in multiple sclerosis: A review

As the most common non-traumatic disabling disease among adolescents, multiple sclerosis (MS) is a devastating neurological inflammatory disease of the central nervous system. Research has not yet fully elucidated its pathogenesis, but it has shown MS to be a complex, multifactorial disease with many interplaying factors. One of these factors, natural killer (NK) cells, lymphocytes of the innate immune system, have recently gained attention due to the effects of daclizumab therapy, causing an expansion of the immunoregulatory subset of NK cells. Since then, NK cells and their relation to MS have been the focus of research, with many new findings being published in the last decade. In this review, NK cells are pictured as potent cytotoxic killers, as well as unique immune-regulators. Additionally, an overview of our current knowledge regarding NK cells in MS is given. The role of NK cells in MS is reviewed in the context of well-established environmental factors and current disease modifying therapies to gain further understanding of the pathogenesis and treatment options in MS.

[Neuromyelitis optica and neuromyelitis optica spectrum disorders]

The review is devoted to up-to-date data on epidemiology, aspects of the pathogenesis of neuromyelitis optica (NMO) and neuromyelitis optica spectrum disorders (NMOSD). The authors consider a role of myelin oligodendrocyte glycoprotein immunoglobulin G (MOG-IgG) in the syndromes phenotypically similar to NMO and NMOSD. Special attention is drawn to the methods of MOG-IgG antibodies detection and indications for testing. The approaches and management for treatment and prevention of NMO relapses, risks of complications during pregnancy and immediately after delivery, as well as methods for their prevention and treatment, are described.

Monoclonal Antibody Therapies for Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

Considerable progress has been made in treatments for multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) over the last several decades. However, the present treatments do not show satisfactory efficacy or safety in a considerable proportion of patients, who experience relapse or disability progression despite receiving treatment and suffer from side effects, which can be severe. Improvements in the understanding of the pathophysiologies of MS and NMOSD have led to numerous therapeutic approaches being proposed and developed. Monoclonal antibodies (mAbs) are receiving increasing attention because of their specificity of action and likelihood of high efficacy with fewer side effects. Many mAbs have been evaluated, and some have been approved for MS or NMOSD treatment. This article reviews the use of mAbs for treating MS and NMOSD, including summarizing their mechanisms of action, efficacy, and safety profiles.

Affinity-matured 'aquaporumab' anti-aquaporin-4 antibody for therapy of seropositive neuromyelitis optica spectrum disorders

Pathogenesis in seropositive neuromyelitis optica spectrum disorders (herein called NMO) involves binding of IgG1 autoantibodies to aquaporin-4 (AQP4) on astrocytes in the central nervous system, which initiates complement and cellular injury. We previously developed an antibody blocking approach for potential therapy of NMO in which an engineered, monoclonal, anti-AQP4 antibody lacking cytotoxicity effector functions (called aquaporumab) blocked binding of NMO autoantibodies to astrocyte AQP4 (Tradtrantip et al. Ann. Neurol. 71, 314-322, 2012). Here, a high-affinity aquaporumab, which was generated by affinity maturation using saturation mutagenesis, was shown to block cellular injury caused by NMO patient sera. Anti-AQP4 antibody rAb-53, a fully human antibody with effector function neutralizing Fc mutations L234A/L235A and affinity-enhancing Fab mutations Y50R/S56R, called AQmab^AM, bound to AQP4 in cell cultures with K_d ~ 18 ng/ml (~0.12 nM), ~8-fold greater affinity than the original antibody. AQmab^AM, but without L234A/L235A Fc mutations, produced complement-dependent cytotoxicity (CDC) with EC₅₀ ~ 82 ng/ml. AQmab^AM prevented CDC produced by sera from eight NMO patients with IC₅₀ ranging from 40 to 80 ng/ml, and similarly prevented antibody-dependent cellular cytotoxicity (ADCC). Mechanistic studies demonstrated that AQmab^AM blocked binding of serum NMO autoantibodies to AQP4. AQmab^AM offers a targeted, non-immunosuppressive approach for therapy of seropositive NMO. Autoantibody blocking may be a useful therapeutic strategy for other autoimmune diseases as well.