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

MOG Antibody Disease: Nuances in Presentation, Diagnosis, and Management

PURPOSE OF REVIEW

Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) is a distinct neuroinflammatory condition characterized by attacks of optic neuritis, transverse myelitis, and other demyelinating events. Though it can mimic multiple sclerosis and neuromyelitis optica spectrum disorder, distinct clinical and radiologic features which can discriminate these conditions are now recognized. This review highlights recent advances in our understanding of clinical manifestations, diagnosis, and treatment of MOGAD.

RECENT FINDINGS

Studies have identified subtleties of common clinical attacks and identified more rare phenotypes, including cerebral cortical encephalitis, which have broadened our understanding of the clinicoradiologic spectrum of MOGAD and culminated in the recent publication of proposed diagnostic criteria with a familiar construction to those diagnosing other neuroinflammatory conditions. These criteria, in combination with advances in antibody testing, should simultaneously lead to wider recognition and reduced incidence of misdiagnosis. In addition, recent observational studies have raised new questions about when to treat MOGAD chronically, and with which agent. MOGAD pathophysiology informs some of the relatively unique clinical and radiologic features which have come to define this condition, and similarly has implications for diagnosis and management. Further prospective studies and the first clinical trials of therapeutic options will answer several remaining questions about the peculiarities of this condition.

Longitudinal change of serum NfL as disease activity biomarker candidate in MOGAD: A descriptive cohort study

BACKGROUND

Myelin oligodendrocyte glycoprotein antibody (MOG-IgG)-associated disease (MOGAD) is an autoinflammatory disease of the central nervous system. MOGAD often follows a relapsing course that can lead to severe disability, but monophasic disease is possible as well. Currently, there is an unmet clinical need for disease activity biomarkers in MOGAD. Serum neurofilament light chain (sNfL) is a sensitive biomarker for neuroaxonal damage. However, data on longitudinal change of sNfL as disease activity biomarker for MOGAD are scarce.

OBJECTIVE

To describe the longitudinal course of sNfL in adult patients with MOGAD in an active as well as a stable disease state in relation to clinical parameters and serum MOG-IgG titers.

METHODS

We conducted a retrospective, exploratory, monocentric cohort study of adult patients with MOGAD. Cohort 1 consisted of five patients in whom NfL was tested as part of their routine clinical workup, all of which had active disease (maximum 6 months since last attack, median 3 months). Cohort 2 comprised 13 patients, which were tested for NfL in the context of a longitudinal study at predefined time intervals, mostly during remission (median 10 months since last attack). sNfL was measured using single molecule array (Simoa) technology at least at two time points (median 3) within a median observation time of 5 months in cohort 1, and at baseline and after a median duration of 12 months in cohort 2. MOG-IgG titers were measured by a fixed cell-based assay.

RESULTS

Change in sNfL correlated positively with change in MOG-IgG titers (rho=0.59, p = 0.027). The variability of sNfL (difference between highest and lowest level) during the observation period was higher in patients who had an attack within six months before baseline (median 37 [interquartile range [IQR] 10-64] pg/ml vs. 2.3 [IQR 1-5] pg/ml, p = 0.006). sNfL increased in patients with an attack during the observation period. Patients with baseline sNfL measurement within two weeks after attack symptom onset displayed relatively low initial sNfL with an increase afterwards.

CONCLUSIONS

Longitudinal sNfL change correlates with MOG-IgG titer change and may be a promising biomarker candidate for disease activity in MOGAD. Increasing sNfL levels might be utilized to adjudicate suspected attacks. In acute attacks, sNfL increase may occur with a delay after symptom onset.

MOG antibody-associated optic neuritis

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is a demyelinating disorder, distinct from multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD). MOGAD most frequently presents with optic neuritis (MOG-ON), often with characteristic clinical and radiological features. Bilateral involvement, disc swelling clinically and radiologically, and longitudinally extensive optic nerve hyperintensity with associated optic perineuritis on MRI are key characteristics that can help distinguish MOG-ON from optic neuritis due to other aetiologies. The detection of serum MOG immunoglobulin G utilising a live cell-based assay in a patient with a compatible clinical phenotype is highly specific for the diagnosis of MOGAD. This review will highlight the key clinical and radiological features which expedite diagnosis, as well as ancillary investigations such as visual fields, visual evoked potentials and cerebrospinal fluid analysis, which may be less discriminatory. Optical coherence tomography can identify optic nerve swelling acutely, and atrophy chronically, and may transpire to have utility as a diagnostic and prognostic biomarker. MOG-ON appears to be largely responsive to corticosteroids, which are often the mainstay of acute management. However, relapses are common in patients in whom follow-up is prolonged, often in the context of early or rapid corticosteroid tapering. Establishing optimal acute therapy, the role of maintenance steroid-sparing immunotherapy for long-term relapse prevention, and identifying predictors of relapsing disease remain key research priorities in MOG-ON.

Oral corticosteroid dosage and taper duration at onset in myelin oligodendrocyte glycoprotein antibody-associated disease influences time to first relapse

BACKGROUND

We sought to identify an optimal oral corticosteroid regimen at the onset of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), which would delay time to first relapse while minimising cumulative corticosteroid exposure.

METHODS

In a retrospective multicentre cohort study, Cox proportional hazards models examined the relationship between corticosteroid course as a time-varying covariate and time to first relapse. Simon-Makuch and Kaplan-Meier plots identified an optimal dosing strategy.

RESULTS

We evaluated 109 patients (62 female, 57%; 41 paediatric, 38%; median age at onset 26 years, (IQR 8-38); median follow-up 6.2 years (IQR 2.6-9.6)). 76/109 (70%) experienced a relapse (median time to first relapse 13.7 months; 95% CI 8.2 to 37.9). In a multivariable model, higher doses of oral prednisone delayed time to first relapse with an effect estimate of 3.7% (95% CI 0.8% to 6.6%; p=0.014) reduced hazard of relapse for every 1 mg/day dose increment. There was evidence of reduced hazard of relapse for patients dosed ≥12.5 mg/day (HR 0.21, 95% CI 0.07 to 0.6; p=0.0036), corresponding to a 79% reduction in relapse risk. There was evidence of reduced hazard of relapse for those dosed ≥12.5 mg/day for at least 3 months (HR 0.12, 95% CI 0.03 to 0.44; p=0.0012), corresponding to an 88% reduction in relapse risk compared with those never treated in this range. No patient with this recommended dosing at onset experienced a Common Terminology Criteria for Adverse Events grade >3 adverse effect.

CONCLUSIONS

The optimal dose of 12.5 mg of prednisone daily in adults (0.16 mg/kg/day for children) for a minimum of 3 months at the onset of MOGAD delays time to first relapse.

Updates in NMOSD and MOGAD Diagnosis and Treatment: A Tale of Two Central Nervous System Autoimmune Inflammatory Disorders

Aquaporin-4-IgG positive neuromyelitis optica spectrum disorder (AQP4+NMOSD) and myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGAD) are antibody-associated diseases targeting astrocytes and oligodendrocytes, respectively. Their recognition as distinct entities has led to each having its own diagnostic criteria that require a combination of clinical, serologic, and MRI features. The therapeutic approach to acute attacks in AQP4+NMOSD and MOGAD is similar. There is now class 1 evidence to support attack-prevention medications for AQP4+NMOSD. MOGAD lacks proven treatments although clinical trials are now underway. In this review, we will outline similarities and differences between AQP4+NMOSD and MOGAD in terms of diagnosis and treatment.

Monoclonal antibody therapies for aquaporin-4-immunoglobulin G-positive neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody-associated disease

Monoclonal antibody therapies mark the new era of targeted treatment for relapse prevention in aquaporin-4 (AQP4)-immunoglobulin G (IgG)-positive neuromyelitis optica spectrum disorder (AQP4-IgG+NMOSD). For over a decade, rituximab, an anti-CD20 B-cell-depleting agent, had been the most effectiveness treatment for AQP4-IgG+NMOSD. Tocilizumab, an anti-interleukin-6 receptor, was also observed to be effective. In 2019, several randomized, placebo-controlled trials were completed that demonstrated the remarkable efficacy of eculizumab (anti-C5 complement inhibitor), inebilizumab (anti-CD19 B-cell-depleting agent), and satralizumab (anti-interleukin-6 receptor), leading to the Food and Drug Administration (FDA) approval of specific treatments for AQP4-IgG+NMOSD for the first time. Most recently, ravulizumab (anti-C5 complement inhibitor) was also shown to be highly efficacious in an open-label, external-controlled trial. Although only some patients with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) warrant immunotherapy, there is currently no FDA-approved treatment for relapse prevention in MOGAD. Observational studies showed that tocilizumab was associated with a decrease in relapses, whereas rituximab seemed to have less robust effectiveness in MOGAD compared to AQP4-IgG+NMOSD. Herein, we review the evidence on the efficacy and safety of each monoclonal antibody therapy used in AQP4-IgG+NMOSD and MOGAD, including special considerations in children and women of childbearing potential.

Is vaccine response to SARS-CoV-2 preserved after switching to anti-CD20 therapies in patients with multiple sclerosis or related disorders?

BACKGROUND

Although vaccination against SARS-CoV-2 is recommended prior to introducing anti-CD20 therapies, limited data are available regarding the evolution of post-vaccinal immunity.

METHODS

This retrospective study compared anti-Spike antibody titres at 6 and 12 months from SARS-CoV-2 vaccination between patients vaccinated before switching to anti-CD20 ('Switch') and two control groups: (1) patients vaccinated under disease-modifying therapies (DMTs) other than fingolimod and anti-CD20 ('Other DMTs'); (2) patients vaccinated on anti-CD20 ('Anti-CD20'). Anti-Spike-specific T-cell responses were compared between 'Switch' and 'Anti-CD20' groups.

RESULTS

Fifty-three patients were included in the 'Switch' group, 54 in the 'Other DMTs' group and 141 in the 'Anti-CD20' group. At 6 months, in the subset of patients who received a booster dose, the 'Switch' group had lower anti-Spike titres compared with the 'Other DMTs' group (median 241.0 IQR (88.0; 504.0) BAU/mL vs 2034 (1155; 4634) BAU/mL, p<0.001), and less patients in the 'Switch' group reached the protective threshold of 264 BAU/mL. The 'Switch' group had higher anti-Spike titres than the 'Anti-CD20' group (7.5 (0.0; 62.1) BAU/mL, p=0.001). Anti-Spike titres were not different between the 'Switch' and 'Other DMTs' groups before booster administration. These results were similar at 12 months. Spike-specific T-cell positivity was similar between the 'Switch' and 'Anti-CD20' groups at 6 and 12 months (60.4% vs 61.0%, p=0.53, and 79.4% vs 87.5%, p=0.31, respectively).

CONCLUSIONS

Despite a primary vaccination performed before the first anti-CD20 cycle, our results suggest weaker immune responses at 6 and 12 months and decreased booster efficacy after introducing anti-CD20. Patients vaccinated prior to anti-CD20 introduction might falsely be considered as fully protected by vaccination.

MOGAD patient autoantibodies induce complement, phagocytosis, and cellular cytotoxicity

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is an inflammatory demyelinating CNS condition characterized by the presence of MOG autoantibodies. We sought to investigate whether human MOG autoantibodies are capable of mediating damage to MOG-expressing cells through multiple mechanisms. We developed high-throughput assays to measure complement activity (CA), complement-dependent cytotoxicity (CDC), antibody-dependent cellular phagocytosis (ADCP), and antibody-dependent cellular cytotoxicity (ADCC) of live MOG-expressing cells. MOGAD patient sera effectively mediate all of these effector functions. Our collective analyses reveal that (a) cytotoxicity is not incumbent on MOG autoantibody quantity alone; (b) engagement of effector functions by MOGAD patient serum is bimodal, with some sera exhibiting cytotoxic capacity while others did not; (c) the magnitude of CDC and ADCP is elevated closer to relapse, while MOG-IgG binding is not; and (d) all IgG subclasses can damage MOG-expressing cells. Histopathology from a representative MOGAD case revealed congruence between lesion histology and serum CDC and ADCP, and we identified NK cells, mediators of ADCC, in the cerebrospinal fluid of relapsing patients with MOGAD. Thus, MOGAD-derived autoantibodies are cytotoxic to MOG-expressing cells through multiple mechanisms, and assays quantifying CDC and ADCP may prove to be effective tools for predicting risk of future relapses.

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD): current understanding and challenges

New diagnostic criteria for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) have recently been proposed, distinguishing this syndrome from other inflammatory diseases of the central nervous system. Seropositivity status for MOG-IgG autoantibodies is important for diagnosing MOGAD, but only in the context of robust clinical characterization and cautious interpretation of neuroimaging. Over the last several years, access to cell-based assay (CBA) techniques has improved diagnostic accuracy, yet the positive predictive value of serum MOG-IgG values varies with the prevalence of MOGAD in any given patient population. For this reason, possible alternative diagnoses need to be considered, and low MOG-IgG titers need to be carefully weighted. In this review, cardinal clinical features of MOGAD are discussed. Key challenges to the current understanding of MOGAD are also highlighted, including uncertainty regarding the specificity and pathogenicity of MOG autoantibodies, the need to identify immunopathologic targets for future therapies, the quest to validate biomarkers that facilitate diagnosis and detect disease activity, and the importance of deciphering which patients with MOGAD require long-term immunotherapy.