Predictors of response to first-line immunosuppressive therapy in neuromyelitis optica spectrum disorders.

BACKGROUND: Azathioprine (AZA) and mycophenolate mofetil (MMF) are the most commonly used first-line therapies for patients with neuromyelitis optica spectrum disorders (NMOSD). However, some patients experience a relapse following AZA or MMF treatment. OBJECTIVES: To identify factors that predict a response to AZA or MMF in NMOSD. METHODS: We retrospectively evaluated medical records from 116 patients who were initially treated with AZA or MMF for at least 6 months. Poor response was defined as ⩾2 relapses or ⩾1 severe relapse. RESULTS: Among the 116 patients, 40 (34%) were classified as poor responders. Logistic regression analyses revealed that a poor response was independently associated with a pre-treatment history of a severe attack ( p < 0.001) and a younger age at disease onset ( p = 0.022). Among the 40 patients with a poor response, 29 (73%) switched to rituximab, and only 3 (10%) had a poor response to rituximab. CONCLUSION: Patients with a pre-treatment history of a severe attack and a younger age of onset exhibited an increased risk of a poor response to AZA or MMF therapy. Identifying patients who are unlikely to respond to AZA or MMF therapy may allow for treatment with more potent therapies that improve treatment outcomes.

Comparison of myelin water fraction values in periventricular white matter lesions between multiple sclerosis and neuromyelitis optica spectrum disorder.

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are inflammatory autoimmune diseases of the central nervous system. We hypothesized that the degree of demyelination within lesions in MS and NMOSD would differ as the pathophysiology of the two diseases do. We used myelin water imaging to compare the myelin water fraction (MWF) in 106 periventricular white matter (PVWM) lesions in 27 MS patients and 51 PVWM lesions in 20 NMOSD patients. The MWF was significantly reduced in the MS compared with the NMOSD lesions, suggesting that myelin loss was more severe in MS than in NMOSD.

Cognitive impairment differs between neuromyelitis optica spectrum disorder and multiple sclerosis.

OBJECTIVE: To compare the frequency and pattern of cognitive impairment (CI) between patients with neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS). METHODS: A total of 82 NMOSD patients, 58 MS patients, and 45 healthy controls (HCs) underwent a neuropsychological assessment. RESULTS: CI was observed in 29% of NMOSD and 50% of MS patients (p < 0.001); CI was considered present if a patient scored lower than the fifth percentile compared with HCs in at least three domains. A lower frequency of CI was consistently found when CI was indicated by at least two failed tests (p < 0.001). MS patients performed worse than did NMOSD patients on verbal learning and verbal and visual memory tests. Levels of education and depression and the interval from disease onset to treatment were associated with a negative influence on cognition in patients with NMOSD. CONCLUSION: CI in patients with NMOSD may be not as common as in patients with MS. MS patients exhibited severe impairment, particularly on learning and memory tests, compared with NMOSD patients. Differential prevalence and patterns of CI between NMOSD and MS patients suggest that the two diseases have different mechanisms of brain injury.

Idiopathic aquaporin-4 antibody negative longitudinally extensive transverse myelitis.

BACKGROUND: Longitudinally extensive transverse myelitis (LETM) is a characteristic manifestation of neuromyelitis optica (NMO). However, not all patients with LETM are positive for aquaporin-4 (AQP4) antibodies. We evaluated the characteristics of idiopathic isolated LETM negative for AQP4 antibodies. METHODS: From the National Cancer Center registry of inflammatory diseases of the central nervous system, patients with LETM as an initial manifestation and follow-up for at least two years were enrolled. Their medical records and MRIs were reviewed retrospectively. AQP4 antibody was confirmed by three different validated methods at least three times. Cerebrospinal fluid (CSF) glial fibrillary acidic protein (GFAP) levels were measured to investigate astrocyte damage. RESULTS: Among 108 patients with first-ever LETM, 55 were positive for AQP4 antibodies (P-LETM) and 53 were consistently negative. Of them, seven were later diagnosed with seronegative NMO, and four were positive for MOG antibodies. The remaining 42 patients (N-LETM) showed several features distinct from P-LETM: male predominance, older age of onset, milder clinical presentation, spinal cord confinement and absence of combined autoimmunity. CSF GFAP levels were not increased in N-LETM but were markedly elevated in P-LETM. CONCLUSIONS: Idiopathic isolated N-LETM is not that rare among first-ever LETM, and has many features distinct from P-LETM where astrocytic damage is evident.

Neutralizing Antibodies Against Interferon-Beta in Korean Patients with Multiple Sclerosis.

BACKGROUND AND PURPOSE: Patients treated with interferon-beta (IFN-ß) can develop neutralizing antibodies (NAbs) against IFN-ß that can negatively affect the therapeutic response. This study assessed the prevalence of NAbs and the impact of NAb positivity on the therapeutic response to IFN-ß in Korean patients with multiple sclerosis (MS). METHODS: This was a multicenter study involving 150 MS patients from 9 Korean medical centers who were treated with IFN-ß for at least 6 months. Sera that had not been influenced by acute treatment were assessed for NAbs using a luciferase reporter gene assay. To evaluate the association between persistent positivity for NAbs and disease activity, NAbs were tested at 2 different time points in 75 of the 150 patients. Disease activity was defined as the presence of clinical exacerbations and/or active MRI lesions during a 1-year follow-up after NAb positivity was confirmed. RESULTS: NAbs were found in 39 of the 150 (26%) MS patients: 30 of the 85 (35%) who were treated with subcutaneous IFN-ß-1b, 9 of the 60 (15%) who were treated with subcutaneous IFN-ß-1a, and 0 of the 5 (0%) who were treated with intramuscular IFN-ß-1a. Thirty of the 39 patients exhibiting NAb positivity were tested at different time points, and 20 of them exhibited persistent NAb positivity. Disease activity was observed more frequently in patients with persistent NAb positivity than in those with transient positivity or persistent negativity [16/20 (80%) vs. 4/55 (7%), respectively; p<0.001]. When disease activity was compared between patients with persistent and transient NAb positivity, the difference was unchanged and remained statistically significant [16/20 (80%) vs. 2/10 (20%), p=0.004]. CONCLUSIONS: These results further support that persistent NAb positivity is associated with disease activity in MS patients treated with IFN-ß.

Multimodal magnetic resonance imaging in relation to cognitive impairment in neuromyelitis optica spectrum disorder.

Cognitive impairment (CI) is reported in 29-57% of patients with neuromyelitis optica spectrum disorder (NMOSD). However, the pathophysiology underlying CI in NMOSD is poorly understood. The present study aims to investigate the predictive values of various conventional and quantitative MRI parameters for cognitive performance in patients with NMOSD. Neurological assessment and conventional, diffusion tensor, and volumetric MRI sequences were collected form 73 patients with NMOSD and 44 healthy controls (HCs). Patients with ≥3 failed tests were considered to have CI. Brain lesion load, gray matter (GM) and white matter (WM) atrophy, deep GM (DGM) atrophy, cortical thickness, and diffuse microstructural WM damage were assessed. Twenty-three (32%) patients with NMOSD had CI. Compared to cognitively preserved (CP) individuals, patients with CI had atrophy in the WM, thalamus, and caudate, decreased fractional anisotropy (FA) and increased mean diffusivity in their WM. A multivariate model indicated that mean FA values in the WM and volume in the nucleus accumbens (NAc) were associated with overall cognition (p = 0.002 and p = 0.008, respectively). Diffuse microstructural damage in the WM and DGM atrophy in the NAc are the strongest predictors of cognitive impairment in patients with NMOSD.

Large-Scale in-House Cell-Based Assay for Evaluating the Serostatus in Patients with Neuromyelitis Optica Spectrum Disorder Based on New Diagnostic Criteria.

BACKGROUND AND PURPOSE: The detection of aquaporin 4-IgG (AQP4-IgG) is now a critical diagnostic criterion for neuromyelitis optica spectrum disorder (NMOSD). To evaluate the serostatus of NMOSD patients based on the 2015 new diagnostic criteria using a new in-house cell-based assay (CBA). METHODS: We generated a stable cell line using internal ribosome entry site-containing bicistronic vectors, which allow the simultaneous expression of two proteins (AQP4 and green fluorescent protein) separately from the same RNA transcript. We performed in-house CBA using serum from 386 patients: 178 NMOSD patients diagnosed according to the new diagnostic criteria without AQP4-IgG, 63 high risk NMOSD patients presenting 1 of the 6 core clinical characteristics of NMOSD but not fulfilling dissemination in space, and 145 patients with other neurological diseases, including 66 with multiple sclerosis. The serostatus of 111 definite and high risk NMOSD patients were also tested using a commercial CBA kit with identical serum to evaluate the correlation between the 2 methods. All assays were performed by two independent and blinded investigators. RESULTS: Our in-house assay yielded a specificity of 100% and sensitivities of 80% (142 of 178) and 76% (48 of 63) when detecting definite- and high risk NMOSD patients, respectively. The comparison with the commercial CBA kit revealed a correlation for 102 of the 111 patients: no correlation was present in 7 patients who were seronegative using the commercial method but seropositive using the in-house method, and in 2 patients who were seropositive using the commercial method but seronegative using the in-house method. CONCLUSIONS: These results demonstrate that our in-house CBA is a highly specific and sensitive method for detecting AQP4-IgG in NMOSD patients.

Leptomeningeal metastasis: Clinical experience of 519 cases.

BACKGROUND: Diagnosis of leptomeningeal metastasis (LM) has become increasingly common because of enhanced detection via routine use of magnetic resonance imaging (MRI) and longer survival of patients by better systemic control. We investigated clinical features and analyzed potential prognostic factors in a large cohort of patients with LM. METHODS: The clinical features of LM developing from systemic cancers were analyzed retrospectively in patients at the National Cancer Center during 2005-2014. RESULTS: A total of 519 patients were enrolled; 497 had solid, 19 had hematopoietic tumors and 3 had tumors of unknown etiology. Among the solid tumors, the most common primary tumor was lung cancer (334 patients), followed by breast cancer (96) and gastrointestinal cancer (39). Median age at onset was 56 years, and the median Karnofsky performance status (KPS) was 60. Thirty-five percent of patients were diagnosed by MRI alone, 22% by cerebrospinal fluid (CSF) cytology alone, and 42% by both. Treatment included chemotherapy alone in 45%, radiation therapy alone in 10%, and both in 17%; 28% received supportive care alone. Median overall survival was 3 months. KPS ≥70, CSF protein level ≤50 mg/dl at the diagnosis of LM, and active treatment were associated independently with longer overall survival. Upon subgroup analysis of lung cancer patients, non-small cell lung cancer was a favorable prognostic factor for overall survival. CONCLUSIONS: Despite improved diagnosis via MRI and vigorous therapy, most patients with LM had poor outcomes. However, patients with a high KPS or normal CSF protein levels had favorable prognoses upon active treatment.

Evaluation of the 2015 diagnostic criteria for neuromyelitis optica spectrum disorder.

OBJECTIVE: To evaluate the application of the 2015 International Panel for NMO Diagnosis (IPND) criteria to consecutive cases of neuromyelitis optica spectrum disorder (NMOSD) in a large cohort of individuals with CNS inflammatory diseases. METHODS: In total, 594 patients with CNS inflammatory diseases were included. Rigorous confirmation of the patients' aquaporin-4 immunoglobulin G antibodies (AQP4-IgG) status throughout the disease duration (mean 9.2 ± 5.7 years) using repeated assays, including ELISA and cell-based assay, was performed. RESULTS: A total of 252 patients fulfilled the IPND criteria (AQP4-IgG positive: 226 [90%], AQP4-IgG negative: 26 [10%]). Of these, 136 (54%) patients met the 2006 neuromyelitis optica criteria. When we assumed an unknown AQP4-IgG status in the confirmed NMOSD group with AQP4-IgG, 162 of 226 (72%) patients with AQP4-IgG were classified as having NMOSD by the IPND criteria. The majority of patients were diagnosed with NMOSD within 2 years of onset (73%) or after a second attack (72%). Acute myelitis (83%) and optic neuritis (65%) were the most common clinical features throughout the disease duration. Optic neuritis (42%) was the most common initial manifestation, followed by acute myelitis (38%) and area postrema syndrome (14%). CONCLUSIONS: The IPND criteria well-reflected the broader clinical spectrum of NMOSD and markedly improved the diagnostic yield compared to the previous criteria, even in patients with an unknown AQP4-IgG status.

Occurrence of Asymptomatic Acute Neuromyelitis Optica Spectrum Disorder-Typical Brain Lesions during an Attack of Optic Neuritis or Myelitis.

We aimed to investigate the frequency of asymptomatic acute brain MRI abnormalities accompanying optic neuritis (ON) or myelitis in neuromyelitis optica spectrum disorder (NMOSD) patients with aquaporin-4 antibodies (AQP4-Ab). We reviewed 324 brain MRI scans that were obtained during acute attacks of ON or myelitis, in 165 NMOSD patients with AQP4-Ab. We observed that acute asymptomatic NMOSD-typical brain lesions accompanied 27 (8%) acute attacks of ON or myelitis in 24 (15%) patients. The most common asymptomatic brain abnormalities included edematous corpus callosum lesions (n = 17), followed by lesions on the internal capsule and/or cerebral peduncle lesions (n = 9), periependymal surfaces of the fourth ventricle (n = 5), large deep white matter lesions (n = 4), periependymal cerebral lesions surrounding the lateral ventricles (n = 3), and hypothalamic lesions (n = 1). If asymptomatic NMOSD-typical brain abnormalities were considered as evidence for DIS, while also assuming that the AQP4-IgG status was unknown, the median time to diagnosis using the 2015 diagnosis criteria for NMOSD was shortened from 28 months to 6 months (p = 0.008). Asymptomatic acute NMOSD-typical brain lesions can be accompanied by an acute attack of ON or myelitis. Identifying these asymptomatic brain lesions may help facilitate earlier diagnosis of NMOSD.

Increased frequency and severity of restless legs syndrome in patients with neuromyelitis optica spectrum disorder.

OBJECTIVES: To investigate the comorbidity of restless legs syndrome (RLS) and neuromyelitis optica spectrum disorder (NMOSD). METHODS: This study enrolled 159 NMOSD patients and 153 age- and gender-matched healthy controls. All participants completed a questionnaire based on the updated International Restless Legs Syndrome Study Group consensus criteria, the International RLS Severity scale, Epworth Sleepiness Scale, Fatigue Severity Scale, and Pittsburgh Sleep Quality Index, and were subsequently interviewed by a neurologist. The frequency and features of RLS were compared between NMOSD patients and healthy controls. The clinical and radiological characteristics of the NMOSD patients with and without RLS were also compared. RESULTS: The frequency and severity of RLS were significantly higher in NMOSD patients than in healthy controls (p = 0.015 for both) and NMOSD patients with RLS had a longer disease duration and more severe disability than those without RLS. CONCLUSIONS: This study indicated importance of considering RLS in NMOSD patients.

Tumefactive demyelinating lesions as a first clinical event: Clinical, imaging, and follow-up observations.

BACKGROUND: Tumefactive demyelinating lesions (TDLs) are associated with a variety of demyelinating diseases in the central nervous system (CNS). However, there are no current guidelines describing how to classify and treat patients with this rare phenotype. Thus, the present study aimed to determine the long-term evolution and disease course of patients initially presenting with TDLs and to describe their clinical and radiographic characteristics. METHODS: From the National Cancer Center registry of inflammatory diseases of the CNS, 31 patients initially presenting with TDLs with follow-up for at least 12 months were enrolled and their demographic, clinical, and radiographic characteristics were evaluated. RESULTS: The median follow-up duration was 37.6 months, during which time 11 patients were diagnosed with neuromyelitis optica spectrum disorder (NMOSD), seven with multiple sclerosis (MS), and 11 remained idiopathic; six did not experience any further clinical events (isolated demyelinating syndrome), and five patients experienced recurrent demyelinating events that were not consistent with either MS or NMOSD. Of the remaining two patients, one was diagnosed with hyperthyroidism-associated demyelination and one with tacrolimus-induced demyelination. CONCLUSIONS: The majority of TDLs evolve into MS or NMOSD. However, despite extensive diagnostic work-ups and long-term follow-ups, the etiology of TDLs was unknown for some patients.

Anti-JC virus antibodies in rituximab-treated patients with neuromyelitis optica spectrum disorder.

Rituximab, a chimeric monoclonal anti-CD20 antibody, has been proposed to be effective for neuromyelitis optica spectrum disorder (NMOSD). A concern for developing progressive multifocal leukoencephalopathy (PML), which is caused by John Cunningham virus (JCV), has been suggested particularly in patients treated long term with rituximab. In this study, using a modified enzyme-linked immunosorbent assay with glutathione S-transferase-tagged VP1 as the antigen, we investigated the seroprevalence of anti-JCV antibodies among 78 Korean patients with NMOSD and the change in anti-JCV antibody serostatus following long-term rituximab treatment. The overall seroprevalence of anti-JCV antibodies was 69 % prior to rituximab administration. Over a mean of 4 years of repeated treatment with rituximab, no patient developed PML. Of 24 initially seronegative patients, none converted into seropositive, whereas six (11 %) of 54 initially seropositive patients converted into seronegative. Our results might support the safety of long-term rituximab treatment in patients with NMOSD with regard to the risk of developing PML.

Treatment Outcomes With Rituximab in 100 Patients With Neuromyelitis Optica: Influence of FCGR3A Polymorphisms on the Therapeutic Response to Rituximab.

IMPORTANCE: Despite the increased use of rituximab therapy in neuromyelitis optica spectrum disorder (NMOSD), the overall efficacy and safety of long-term rituximab treatment in a large group of patients is uncertain. Furthermore, the identification of a predictor of rituximab response is an important issue for assessing the individual risk-benefit of therapy and making treatment decisions. OBJECTIVE: To assess the long-term clinical efficacy and safety of rituximab treatment in patients with NMOSD and the influence of fragment c gamma receptor 3A (FCGR3A) polymorphisms on rituximab response. DESIGN, SETTING, AND PARTICIPANTS: A retrospective review of 100 patients with relapsing NMOSD treated with rituximab for at least 6 months, from February 1, 2006, to January 31, 2015, at the institutional referral center. After induction therapy, a single infusion of rituximab (375 mg/m2) as maintenance therapy was administered whenever a reemergence of CD27+ memory B cells among peripheral blood mononuclear cells occurred. Using an allele-specific polymerase chain reaction-based method, the gene polymorphisms FCGR3A-V158F were assessed. MAIN OUTCOMES AND MEASURES: The primary end point was annualized relapse rate; disability (Expanded Disability Status Scale score), safety of rituximab treatment, event of insufficient memory B-cell depletion following rituximab, and time to retreatment of rituximab were secondary end points. RESULTS: By January 31, 2015, a total of 100 patients received repeated rituximab treatment during a median of 67 months. Of these patients, 41 had more than 5 years' follow-up and 24 had more than 7 years' follow-up. The annualized relapse rate was reduced significantly by 96% (mean [SD] annualized relapse rate of prerituximab vs postrituximab, 2.4 [2.0] vs 0.1 [0.6]) and disability improved or stabilized in 96% of patients. Rates of adverse events were generally stable. The FCGR3A-F allele was associated with a risk of relapse while receiving rituximab treatment (additive model, P < .05; recessive model, P = .04; maximum, P = .03) and insufficient memory B-cell depletion (additive model, P = .03; recessive model, P = .03; maximum, P = .03). CONCLUSIONS AND RELEVANCE: Repeated rituximab treatment for NMOSD was observed in an increasing number of patients and increasing duration of exposure and maintained good efficacy and a safety profile consistent with previous reports. The finding of a relationship between FCGR3A genetic polymorphisms and rituximab response suggests the importance of individualized rituximab treatment strategies in NMOSD.

A longitudinal brain magnetic resonance imaging study of neuromyelitis optica spectrum disorder.

Brain involvement is commonly seen in patients with neuromyelitis optica spectrum disorder (NMOSD). However, little is known about the chronic changes of acute brain lesions on MRI over time. Here, our objective was to evaluate how acute brain MRI lesions in NMOSD changed on follow-up MRI. We reviewed the MRIs of 63 patients with NMOSD who had acute brain lesions and follow-up MRI over an interval of at least 3 months. Of the 211 acute brain lesions, 24% of lesions disappeared completely on T2-weighed images (WI) and a decrease in size ≥50% on T2-WI was observed in 58% of lesions on follow-up MRI. However, 47% of lesions revealed focal T1-hypointensity and, in particular, 18% showed focal cystic changes. Cystic changes were observed most commonly in corticospinal tract and corpus callosal lesions whereas the vast majority of lesions in the cerebellum, basal ganglia and temporal white matter resolved completely. MRI remission on T2-WI occurred in 82% of lesions, while approximately half of the lesions presented foci of T1-hypointensity, which may be considered a severe tissue injury over time. The extent of brain injury following an acute brain lesion in NMOSD may depend on the location of the lesion.

Mycophenolate mofetil in the treatment of neuromyelitis optica spectrum disorder.

IMPORTANCE: Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disorder of the central nervous system. Recently, various immunosuppressant medications were introduced as therapeutic options for preventing relapse of NMOSD. However, our understanding of the effectiveness of mycophenolate mofetil (MMF) in treating patients with NMOSD is based on only a small number of studies. OBJECTIVE: To evaluate the efficacy and safety of MMF treatment in patients with NMOSD. DESIGN, SETTING, AND PARTICIPANTS: A 3-center retrospective review of our experiences, examining results from 59 patients with NMOSD (24 with neuromyelitis optica and 35 with a limited form of the disease) who were treated with MMF (1000-2000 mg/d). MAIN OUTCOMES AND MEASURES: Patients' annualized relapse rate, disability as measured by the Expanded Disability Status Scale, and experience of adverse effects due to MMF were assessed. RESULTS: Of the 59 patients, 1 with NMOSD who had to discontinue MMF use in the first month due to a rash was excluded. The remaining 58 patients were included in the drug-efficacy analysis. The median post-MMF annualized relapse rate was significantly lower than the pre-MMF annualized relapse rate (0.0 vs 1.5; P < .001). The Expanded Disability Status Scale scores also significantly decreased after MMF treatment (3.0 vs 2.5; P = .005). Thirty-five patients (60%) were relapse free, and Expanded Disability Status Scale scores were stabilized or improved in 53 patients (91%). Fourteen patients discontinued MMF treatment owing to ongoing relapse (10 patients), rash (1 patient), pregnancy (1 patient), and financial problems (2 patients), but MMF was generally well tolerated. CONCLUSIONS AND RELEVANCE: In this observational study, MMF treatment induced reduction of relapse frequency, stabilized or improved disability, and was well tolerated in patients with NMOSD.

Validity of korean versions of the multiple sclerosis impact scale and the multiple sclerosis international quality of life questionnaire.

BACKGROUND AND PURPOSE: Assessment of the health-related quality of life (HRQoL) is important in clinical evaluations of multiple sclerosis (MS) patients for quantifying the impact of illness and treatment on their daily lives. Although MS-specific HRQoL instruments have been used internationally, there are no data regarding HRQoL instruments specifically designed for patients with MS in Korea. The objective of this study was to determine the reliability and validity of the Korean Multiple Sclerosis Impact Scale (MSIS-29) and the Multiple Sclerosis International Quality of Life (MusiQoL) questionnaire. METHODS: Fifty-six patients with MS were recruited from June 2009 to February 2010 at the National Cancer Center in Korea. The original English versions of the MSIS-29 scale and the MusiQoL questionnaire were translated into Korean and evaluated for their acceptability, reliability, and validity. RESULTS: The patients wereaged 36.5±8.6 years (mean±SD; range, 20-56 years). Their score on the Expanded Disability Status Scale was 2.0±1.9 (mean; range, 0-7.5), and their disease duration was 5.2±4.7 years (mean±SD; range, 1-24 years). The Korean versions of the MSIS-29 and MusiQoL questionnaires showed satisfactory psychometric properties, including construct validity (item-internal consistencies of 0.59-0.95 and 0.59-0.92, respectively; item-discriminant validities of 95-100% and 93.8-100%), internal consistency (Cronbach's alpha coefficients of 0.96-0.97 and 0.77-0.96), reliability (intraclass correlation coefficients of 0.78-0.90 and 0.50-0.93), unidimensionality (Loevinger scalability coefficients of 0.70-0.78 and 0.63-0.90), and acceptability. External validity testing indicated the presence of significant correlations between similar aspects of the two questionnaires. CONCLUSIONS: The Korean translated versions of the MSIS-29 and MusiQoL questionnaires demonstrated reliability and validity for measuring HRQoL in Korean patients with MS.

A 5-year follow-up of rituximab treatment in patients with neuromyelitis optica spectrum disorder.

IMPORTANCE: A previous 2-year analysis of repeated rituximab treatment in patients with neuromyelitis optica (NMO) revealed significant improvements in relapse rates and disability. We report the findings from the longest follow-up of rituximab treatment in NMO, which provide reassurance regarding the long-term efficacy and safety of rituximab in NMO. OBJECTIVE: To report the results of rituximab treatment in patients with relapsing NMO or NMO spectrum disorder (NMOSD) for a median of 60 months. DESIGN, SETTING, AND PARTICIPANTS: Retrospective case series in an institutional referral center for multiple sclerosis, including 30 patients with relapsing NMO or NMOSD. INTERVENTIONS: After induction therapy, a single infusion of rituximab (375 mg/m2) as maintenance therapy was administered whenever the frequency of reemerging CD27+ memory B cells in peripheral blood mononuclear cells, as measured with flow cytometry, exceeded 0.05%in the first 2 years and 0.1% thereafter. MAIN OUTCOMES AND MEASURES: Annualized relapse rate (ARR), disability (Expanded Disability Status Scale score), change in anti­aquaporin 4 antibody, and safety of rituximab treatment. RESULTS: Of 30 patients, 26 (87%) exhibited a marked reduction in ARR over 5 years (mean [SD] pretreatment vs posttreatment ARR, 2.4 [1.5] vs 0.3 [1.0]). Eighteen patients (60%) became relapse free after rituximab treatment. In 28 patients (93%), the disability was either improved or stabilized after rituximab treatment. No serious adverse events leading to discontinuation were observed during follow-up. CONCLUSIONS AND RELEVANCE: Repeated treatment with rituximab in patients with NMOSD over a 5-period, using an individualized dosing schedule according to the frequency of reemerging CD27+ memory B cells, leads to a sustained clinical response with no new adverse events.