Individualized regimen of low-dose rituximab monotherapy for new-onset AChR-positive generalized myasthenia gravis

Artificial intelligence-based personalised rituximab treatment protocol in membranous nephropathy (iRITUX): protocol for a multicentre randomised control trial

INTRODUCTION

Membranous nephropathy is an autoimmune kidney disease and the most common cause of nephrotic syndrome in non-diabetic Caucasian adults. Rituximab is now recommended as first-line therapy for membranous nephropathy. However, Kidney Disease Improving Global Outcomes guidelines do not recommend any specific protocol. Rituximab bioavailability is reduced in patients with membranous nephropathy due to urinary drug loss. Underdosing of rituximab is associated with treatment failure. We have previously developed a machine learning algorithm to predict the risk of underdosing. We have retrospectively shown that patients with a high risk of underdosing required higher doses of rituximab to achieve remission. The aim of this prospective study is to evaluate the efficacy of algorithm-driven rituximab treatment in patients with membranous nephropathy compared to standard treatment.

METHODS

A multicentre, randomised, controlled, open-label, prospective superiority clinical trial will be conducted in 13 French hospitals. 130 consecutive patients with primary membranous nephropathy and active nephrotic syndrome will be randomised to either the standard protocol control group (two 1 g rituximab infusions on days 0 and 15) or the algorithm-driven rituximab treatment group. In the latter, the rituximab dose will depend on the algorithm-estimated risk of underdosing. Patients with an algorithm-estimated risk of underdosing ≤50% will receive 1 g of rituximab on days 0 and 15. Patients with an algorithm-estimated risk of underdosing between 51% and 75% will receive 1 g of rituximab on days 0, 15 and 30. Finally, patients with an estimated risk of underdosing >75% will receive 1 g of rituximab on days 0, 15, 30 and 45. The primary study outcome is the rate of clinical remission (complete or partial) at month 6 after treatment initiation. The secondary outcomes include clinical remission at month 12, immunological remission, proteinuria, albuminuria, serum creatinine, estimated glomerular filtration rate, phospholipase A2 receptor type 1 antibody titre, anti-rituximab antibody occurrence, lymphocyte count, serum rituximab level and related adverse events.

ETHICS AND DISSEMINATION

The trial received ethics approval from the local ethics boards. The results of this study will confirm whether algorithm-driven rituximab treatment is more effective in inducing remission than the standard regimen and thus may contribute to improving management of patients with membranous nephropathy. The results of our study will be submitted to a peer-review journal.

TRIAL REGISTRATION NUMBER

NCT06341205 trial number. Registered on 2 April 2024.

Nomogram for the prediction of relapse factors in patients with neuromyelitis optica spectrum disorder during rituximab treatment

OBJECTIVES

Develop a nomogram to analyse the factors influencing the relapse of neuromyelitis optica spectrum disorder (NMOSD) during rituximab (RTX) treatment.

METHODS

A retrospective analysis of 214 NMOSD patients identified 181 with AQP4-IgG-seropositive. 32 patients who relapsed during RTX treatment were included, and 122 sets of lymphocyte subset monitoring data were collected. 110 sets of data were finally included and divided into relapse (n = 30) and nonrelapse (n = 80) groups depending on whether a relapse occurred between two adjacent RTX treatments. Logistic and LASSO regressions were used to identify the relevant factors influencing NMOSD relapse, and a nomogram was constructed. Receiver operating characteristic (ROC) curves were generated to evaluate the nomogram's ability to differentiate, and the bootstrap method was utilized for internal validation. Calibration curve and decision curve analysis were also conducted.

RESULTS

Comparing baseline data revealed differences in the RTX administration interval, CD3-CD19+ B lymphocyte and CD3-CD56+ NK cell levels. The RTX administration interval and the level of CD3-CD19+ B lymphocytes were independent variables influencing relapse. The nomogram had an area under the curve (AUC) of 0.71 and a 95% confidence interval (CI) of 0.58-0.83. The Hosmer-Lemeshow (H-L) goodness-of-fit test yielded a χ2 = 11.80 (p = 0.16). Decision curve analysis revealed that the model provided greater net benefits within the threshold probability range of 0.18-0.98.

CONCLUSION

The nomogram developed in this study showed that the RTX administration interval and CD3-CD19+ B lymphocyte levels independently influence NMOSD relapse, indicating good discriminative ability, consistency, and clinical benefits.

Efficacy and safety of different dosages of rituximab for myasthenia gravis: a single-arm meta-analysis

BACKGROUND

Rituximab (RTX) is one of the treatment options for refractory myasthenia gravis (MG), yet the optimal dosing schedule remains undetermined. Our study aims to explore this issue and offer a valuable reference for clinical dosing.

METHODS

This is a single-arm meta-analysis. Studies in adults with myasthenia gravis published before 31 December 2023 were searched in PubMed, Web of Science, and other databases. Two primary effectiveness outcomes were analyzed: (1) Proportion of patients achieving minimal manifestation status (MMS) or better, (2) Change in Quantitative MG Score (QMGs) after RTX treatment. Safety outcomes included the incidence and description of serious adverse events (SAEs) and adverse events (AEs). Forest plots were generated to provide an overview and detailed combined effects. Publication bias was evaluated using funnel plots and the Egger test. Conventional dose refers to an RTX regimen similar to that used for the treatment of B-cell lymphoma: 375 mg/m2 per week for 4 weeks or 1000 mg for Weeks 1 and 3. Dosing regimens below the conventional dose in a treatment cycle are defined as low dose.

RESULTS

A total of 1037 MG patients received RTX treatment. Overall, 59.0% (95% CI: 48.2-69.8%, n = 599) of patients achieved MMS or better, with a mean decrease in QMGs of 6.81 (95% CI, -9.27 to -4.35, n = 222). The low-dose group showed a higher proportion of patients achieving MMS or better (76.6% vs 51.6%) and a more significant decrease in QMGs from baseline (-9.04 vs -3.62) compared to the conventional dose group (P < 0.01). Differences in the incidence of SAEs and AEs between the two groups were not significant (P > 0.05). Univariate meta-regression analyses showed that the dose administered was significantly associated with the proportion of MMS or better and the change in QMGs, whereas the proportion of Musk patients was not significantly associated with any of the outcomes. Stepwise logistic regression analyses showed that non-refractory MG, mild disease severity (MGFA classification), and low-dose were significant predictors for achieving an MMS or better prognosis, whereas for achieving improvement or better, only low dose was an independent predictor.

CONCLUSION

RTX can improve clinical symptoms, reduce QMGs in MG patients and the use of oral glucocorticoids and other immunosuppressants. The efficacy of low-dose RTX in treating MG patients is more effective than conventional-dose RTX and demonstrates a better safety profile. Mild disease severity, non-refractory MG, low dose, and MuSK-MG over AChR-MG predict better efficacy. Large randomized controlled trials are necessary to evaluate the efficacy and safety of RTX in MG patients and its various subtypes.

Efficacy and safety of combined low-dose rituximab regimen for chronic inflammatory demyelinating polyradiculoneuropathy

OBJECTIVE

To determine the efficacy and safety of combined low-dose rituximab with conventional therapy for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) treatment.

METHODS

Total 73 patients with CIDP were enrolled for the retrospective cohort study, and divided into conventional first-line therapy cohort (n = 40) and combined low-dose rituximab (100 mg per infusion) cohort (n = 33). The outcome measures include scores of I-RODS, mRS, INCAT, ONLS, TSS, and COMPASS 31 scale at baseline and regular four visits (4, 16, 28, and 52 weeks), as well as proportion of favorable response and outcome, corticosteroids dosage, and deterioration occurrence during follow-up.

RESULTS

Compared to conventional therapy cohort, combined rituximab cohort presented better improvements and higher proportion of favorable response in scales assessments at each visit, as well as significantly reduced corticosteroids dosage and deterioration occurrence during the follow-up. Analyses of subgroups showed better improvements in both typical CIDP and CIDP variants in combined rituximab cohort than those in conventional therapy cohort, but had no differences between each other. Early initiating combined rituximab regimen (<10 weeks) showed better improvements than delayed initiation (≥10 weeks) at the first three visits within 28 weeks, while had no difference in favorable prognoses at the last visit of 52 weeks after once reinfusion. No rituximab correlated serious adverse events were reported in our patients.

INTERPRETATION

Our simplified regimen of combined low-dose rituximab has been firstly demonstrated for the better efficacy and safety than conventional therapy in CIDP treatment.

Rituximab in the Treatment of Non-Infectious Uveitis: A Review

Non-infectious uveitis (NIU) is an immune-mediated disorder manifesting as ocular pain, redness, floaters, and photophobia, and is a leading cause of preventable blindness. Managing NIU presents considerable challenges due to the condition's resistance to high-dose corticosteroids and various immunotherapies. This review assesses the efficacy and safety of rituximab (RTX) in the treatment of NIU, based on individual case reports and small-scale studies. A cohort of 78 patients (20 males, 58 females), with a mean onset age of 32.3 years (range 8-72), was analyzed. Juvenile idiopathic arthritis (JIA) was the most frequently associated comorbidity, affecting 28 patients, while anterior uveitis was the predominant subtype, observed in 26 of 47 cases. Prior to RTX therapy, patients had been treated with an average of 1.7 conventional immunosuppressive agents (range 0-5) and 1.1 biologics (range 0-4). RTX was introduced following the failure of high-dose corticosteroids, immunosuppressive drugs, and biologics to control the uveitis. The median time from diagnosis to RTX initiation was 7.7 years (range 0.25-21). Post-RTX, 44.2% of patients experienced improvement in visual acuity, 79.5% achieved resolution of ocular inflammation, and 8.9% showed partial improvement. Additionally, 81.1% were able to reduce their corticosteroid dosage. Overall, 88.6% (69 out of 78) demonstrated a positive response to RTX treatment. These findings indicate that RTX may serve as an effective therapeutic option for NIU unresponsive to steroids and multiple immunotherapies. It may also warrant consideration as a potential first-line treatment in certain cases.

Efficacy and safety of low-dose rituximab in the treatment of myasthenia gravis: a systemic review and meta-analysis

Background

Rituximab (RTX) is a monoclonal antibody that has been increasingly used in the treatment of myasthenia gravis (MG). In most studies, the therapeutic protocol of RTX has been similar to that adopted for B cell lymphoma, with an increasing number of studies aimed at exploring the efficacy of low-dose RTX in MG. However, the beneficial effects of low-dose RTX in MG remain a subject of critical debate.

Methods

This study was conducted following the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. Two reviewers (Xishuai Yang and Bingxia Li) independently conducted searches across multiple databases, including PubMed, MEDLINE, EMBASE, Web of Science, Cochrane Library, and China National Knowledge Infrastructure (CNKI). A meta-analysis, utilizing representative forest plots, was performed to assess "Improved clinical status" and changes in the Quantitative Myasthenia Gravis (QMG) score before and after treatment.

Results

A total of 17 studies involving 292 patients were included in the meta-analysis. A noticeable improvement in clinical status was observed in 91% of patients at the final follow-up after therapy (95% CI: 84-96%, P < 0.001). The QMG score showed a significant reduction following the treatment, with a standardized mean difference (SMD) of -1.69 (95% CI: -2.21 to -1.16, Z = 6.29, P < 0.001). In the acetylcholine receptor antibody-positive myasthenia gravis (AChR-MG) group, 90% of patients achieved improved clinical status (95% CI: 80-97%, P < 0.001) and the QMG score significantly decreased after low-dose RTX treatment, with an SMD of -1.51 (95% CI: -0.80 to -2.21, Z = 4.50, P < 0.001). In the muscle-specific kinase antibody-positive myasthenia gravis (MuSK-MG) group, 97% of patients achieved improved clinical status (95% CI: 89-100%, P < 0.001). The QMG score also significantly decreased following low-dose RTX treatment, with an SMD of -2.31 (95% CI: -2.99 to -1.62, Z = 6.60, P < 0.001). Adverse effects were reported in 29 out of 207 patients (14%, including infusion reactions in 22 patients (10.1%), infections in three patients (1.45%), cytopenia in two patients (0.96%), eosinophilia in one patient (0.48%), and hemiplegia in one patient (0.48%). Additionally, one patient (0.48%) succumbed to complications from invasive thymoma.

Conclusion

Our meta-analysis shows that low-dose RTX is both effective and safe for treating MG.

Systematic Review Registration

PROSPERO, identifier: CRD42024509951.

Treating myasthenia gravis beyond the eye clinic

Myasthenia gravis (MG) is one of the most well characterised autoimmune disorders affecting the neuromuscular junction with autoantibodies targeting the acetylcholine receptor (AChR) complex. The vast majority of patients present with ocular symptoms including double vision and ptosis, but may progress on to develop generalised fatiguable muscle weakness. Severe involvement of the bulbar muscles can lead to dysphagia, dysarthria and breathing difficulties which can progress to myasthenic crisis needing ventilatory support. Given the predominant ocular onset of the disease, it is important that ophthalmologists are aware of the differential diagnosis, investigations and management including evolving therapies. When the disease remains localised to the extraocular muscles (ocular MG) IgG1 and IgG3 antibodies against the AChR (including clustered AChR) are present in nearly 50% of patients. In generalised MG this is seen in nearly 90% patients. Other antibodies include those against muscle specific tyrosine kinase (MuSK) and lipoprotein receptor related protein 4 (LRP4). Even though decremental response on repetitive nerve stimulation is the most well recognised neurophysiological abnormality, single fibre electromyogram (SFEMG) in experienced hands is the most sensitive test which helps in the diagnosis. Initial treatment should be using cholinesterase inhibitors and then proceeding to immunosuppression using corticosteroids and steroid sparing drugs. Patients requiring bulbar muscle support may need rescue therapies including plasma exchange and intravenous immunoglobulin (IVIg). Newer therapeutic targets include those against the B lymphocytes, complement system, neonatal Fc receptors (FcRn) and various other elements of the immune system.

Advancements and prospects of novel biologicals for myasthenia gravis: toward personalized treatment based on autoantibody specificities

Myasthenia gravis (MG) is an antibody-mediated autoimmune disease with a prevalence of 150-250 cases per million individuals. Autoantibodies include long-lived antibodies against the acetylcholine receptor (AChR), mainly of the IgG1 subclass, and IgG4, produced almost exclusively by short-lived plasmablasts, which are prevalent in muscle-specific tyrosine kinase (MuSK) myasthenia gravis. Numerous investigations have demonstrated that MG patients receiving conventional medication today still do not possess satisfactory symptom control, indicating a substantial disease burden. Subsequently, based on the type of the autoantibody and the pathogenesis, we synthesized the published material to date and reached a conclusion regarding the literature related to personalized targeted therapy for MG. Novel agents for AChR MG have shown their efficacy in clinical research, such as complement inhibitors, FcRn receptor antagonists, and B-cell activating factor (BAFF) inhibitors. Rituximab, a representative drug of anti-CD20 therapy, has demonstrated benefits in treatment of MuSK MG patients. Due to the existence of low-affinity antibodies or unidentified antibodies that are inaccessible by existing methods, the treatment for seronegative MG remains complicated; thus, special testing and therapy considerations are necessary. It may be advantageous to initiate the application of novel biologicals at an early stage of the disease. Currently, therapies can also be combined and individualized according to different types of antibodies. With such a wide range of drugs, how to tailor treatment strategies to patients with various conditions and find the most suitable solution for each MG profile are our necessary and urgent aims.

Efficacy and safety of low- and ultralow-dose rituximab in neuromyelitis optica spectrum disorder

BACKGROUND

Rituximab effectively targets B cells and reduces relapses in neuromyelitis optica spectrum disorder (NMOSD). But the ideal dosage and treatment intervals remain unanswered. We aimed to assess the efficacy and safety of low and ultralow-dose rituximab in NMOSD.

METHODS

We conducted a retrospective analysis of NMOSD patients treated with rituximab at two Chinese tertiary hospitals. Patients received either a low-dose regimen (500 mg reinfusion every 6 months) or an ultralow-dose regimen: 100 to 300 mg rituximab based on CD19+B cells (100 mg for 1-1.5% of peripheral blood mononuclear cells, 200 mg for 1.5-5%, and 300 mg for over 5%).

RESULTS

We analyzed data from 136 patients (41 in the low-dose group, 95 in the ultralow-dose group) with median follow-up durations of 43 and 34.2 months, respectively. Both groups exhibited similar sex distribution, age at disease onset, annual relapse rate, and baseline disease duration. Survival analysis showed that ultralow-dose rituximab was noninferior to low-dose rituximab in preventing relapses. Infusion reactions occurred in 20 of 173 (11.6%) low-dose treatments and 9 of 533 (1.7%) ultralow-dose treatments. B-cell re-emergence was observed in 137 of 236 (58.1%) monitors in the low-dose group and 367 of 1136 (32.3%) monitors in the ultralow-dose group.

CONCLUSION

Ultralow dose rituximab was noninferior to low-dose rituximab in preventing NMOSD relapses. A randomized controlled trial is essential to validate these findings.

Therapeutic effect of ofatumumab in patients with myasthenia gravis: immunoregulation of follicular T helper cells and T helper type 17 cells

Introduction

This study aimed to study the therapeutic effects of ofatumumab in patients with myasthenia gravis (MG) in addition to the immunomodulatory effects on peripheral follicular T helper (Tfh) cells and T helper type 17 (Th17) cells.

Methods

Thirty-one patients with anti-acetylcholine receptor (AChR) antibody-positive MG were included in this study. At weeks 0, 1, 2, and 4, an initial dose of 20 mg of ofatumumab was injected subcutaneously, with a 2-month follow-up after completing this first cycle. At baseline, 1 month, and 3 months, we assessed the Quantitative MG (QMG), 15-item MG-Quality of Life (MG-QOL15), and MG-Activities of Daily Living (MG-ADL) scales and measured the frequencies of Tfh, Th17, and B cells and the levels of anti-AChR antibody, IL-6, IL-21, and IL-17 in the peripheral blood.

Results

At 1 month and 3 months, the QMG, MG-QOL15, and MG-ADL scores were all significantly reduced. At 3 months, doses of prednisone were reduced by an average of 37%. Decreased frequencies of Tfh and Th17 cells, depletion of B cells, and reduced levels of IL-6, IL-21, and IL-17 were all observed at 1 month or 3 months.

Discussion

Therefore, the therapeutic effect of ofatumumab could be detected after one cycle of treatment, which was maintained for 2 months. The immunomodulatory effect of ofatumumab during the observation period may involve depletion of B cells, reduction of Tfh and Th17 cells frequencies, and reduced levels of IL-6, IL-21, and IL-17. The findings provide novel data for the potential application of ofatumumab in MG.

Myasthenia gravis: Molecular mechanisms and promising therapeutic strategies

Myasthenia gravis (MG) is a type of autoimmune disease caused by the blockage of neuromuscular junction transmission owing to the attack of autoantibodies on transmission-related proteins. Related antibodies, such as anti-AChR, anti-MuSK and anti-LRP4 antibodies, can be detected in most patients with MG. Although traditional therapies can control most symptoms, several challenges remain to be addressed, necessitating the development of more effective and safe treatment strategies for MG. With the in-depth exploration on the mechanism and immune targets of MG, effective therapies, especially therapies using biologicals, have been reported recently. Given the important roles of immune cells, cytokines and intercellular interactions in the pathological process of MG, B-cell targeted therapy, T-cell targeted therapy, proteasome inhibitors targeting plasma cell, complement inhibitors, FcRn inhibitors have been developed for the treatment of MG. Although these novel therapies exert good therapeutic effects, they may weaken the immunity and increase the risk of infection in MG patients. This review elaborates on the pathogenesis of MG and discusses the advantages and disadvantages of the strategies of traditional treatment and biologicals. In addition, this review emphasises that combined therapy may have better therapeutic effects and reducing the risk of side effects of treatments, which has great prospects for the treatment of MG. With the deepening of research on immunotherapy targets in MG, novel opportunities and challenges in the treatment of MG will be introduced.

Immune checkpoint inhibitors induced side effects of the peripheral nervous system

PURPOSE OF REVIEW

This review highlights recent knowledge on the diagnosis and treatment of immune checkpoint inhibitor-induced neurological side effects (irNAE) focussing on the neuromuscular system.

RECENT FINDINGS

irNAEs mainly resemble sporadic neuromuscular autoimmune diseases and paraneoplastic neurological syndromes. However, neurological symptoms may be unspecific (muscle weakness, fatigue) in the oncological setting and carry the risk of misdiagnosis and delayed therapeutic intervention. The role of disease-specific neuromuscular autoantibodies in the diagnosis is controversial as preexisting autoantibodies may otherwise be present before immune checkpoint inhibitor (ICI) treatment without clinical symptoms and may not develop in case of irNAE manifestation. A new necrotising form of myositis (irMyositis) has been described presenting with facial weakness and ptosis mimicking myasthenia gravis. It comes along with a high rate of severe myocarditis accounting for a triad overlap syndrome (myasthenia/myositis/myocarditis). The role of modern biologicals in the treatment of irNAEs has to be determined.

SUMMARY

irNAEs are rare but carry the risk of permanent morbidity and mortality. Early suspicion and diagnosis are key to prevent neurological sequelae. Beyond interruption of ICI administration, treatment corresponds to sporadic autoimmune diseases. The myasthenia/myositis/myocarditis overlap syndrome deserves special attention as it carries the highest risk of mortality. The role of neurotoxic pretreatment regimens, preexisting subclinical neurological autoimmune diseases and the risk of ICI-re-challenge after irNAEs has to be further investigated.

Novel Immunotherapies for Myasthenia Gravis

Myasthenia gravis (MG), a prototype autoimmune neurological disease, had its therapy centred on corticosteroids, non-steroidal broad-spectrum immunotherapy and cholinesterase inhibitors for several decades. Treatment-refractory MG and long-term toxicities of the medications have been major concerns with the conventional therapies. Advances in the immunology and pathogenesis of MG have ushered in an era of newer therapies which are more specific and efficacious. Complement inhibitors and neonatal Fc receptor blockers target disease-specific pathogenic mechanisms linked to myasthenia and have proven their efficacy in pivotal clinical studies. B cell-depleting agents, specifically rituximab, have also emerged as useful for the treatment of severe MG. Many more biologicals are in the pipeline and in diverse stages of development. This review discusses the evidence for the novel therapies and the specific issues related to their clinical use.

Knowledge mapping of targeted immunotherapy for myasthenia gravis from 1998 to 2022: A bibliometric analysis

Background

The treatment of myasthenia gravis (MG) has advanced from steroids and traditional immunosuppressants to targeted immunotherapy. Targeted immunotherapy has been successfully employed in clinical practice in recent years. This study aimed to explore the emerging trend of targeted immunotherapy in MG and summarize the knowledge structure through bibliometric methods.

Methods

The Web of Science Core Collection database (WoSCC) was chosen to retrieve the literature on targeted immunotherapy for MG. Two bibliometric analysis software, VOSviewer and CiteSpace, and bibliometric online platform were mainly used to evaluate the contributions from countries/regions, institutions, journals, and authors through the construction and visualization of bibliometric networks. By systematically reviewing a knowledge domain, future research developments were determined. The R version 4.1.2 and Microsoft Excel 365 were used for statistical analysis.

Results

A total of 562 original articles and 262 reviews relevant to MG targeted immunotherapy were included. The number of publications on targeted immunotherapy for MG exhibited a two-phase advancement. The first stage showed a steady growth trend from 1998 to 2016, with an annual number of no more than 35 publications. The second stage revealed an explosive growth trend from 2017, reaching a peak number of publications in 2020. The United States ranked first in the number of publications, citations, and h-index. The author with the highest citation and h-index was Vincent A. And 28.03% of the articles were published in the top 10 journals. In addition to “myasthenia gravis”, the keyword with the highest consideration was “rituximab”, followed by “double-blind”, which indicate research hotspots gradually from basic research to clinical research over time, especially in the field of targeted immunotherapy. The MG treatment has entered a personalized precision treatment phase. Exploration into new target molecules and conducting high-quality randomized controlled trials on existing biological agents are the further research direction.

Conclusion

The current study summarized the global research trends concerning targeted immunotherapy for MG. Research interests gradually advanced from basic research to clinical research. MG treatment has entered a personalized precision treatment phase. Further investigations into new target molecules and high-quality randomized controlled trials on existing biological agents are required urgently to direct future immunotherapy research.

Effect of low-dose rituximab treatment on autoimmune nodopathy with anti-contactin 1 antibody

Background

Autoimmune nodopathy with anti-contactin-1 (CNTN1) responds well to rituximab instead of traditional therapies. Although a low-dose rituximab regimen was administered to patients with other autoimmune diseases, such as myasthenia gravis and neuromyelitis optica spectrum disorders, and satisfactory outcomes were obtained, this low-dose rituximab regimen has not been trialed in anti-CNTN1-positive patients.

Methods

Anti–CNTN1 nodopathy patients were enrolled in this prospective, open-label, self-controlled pilot study. A cell-based assay was used to detect anti-CNTN1 antibodies and their subclasses in both serum and cerebrospinal fluid. Clinical features were evaluated at baseline, 2 days, 14 days, and 6 months after single low-dose rituximab treatment (600 mg). The titers of the subclasses of anti-CNTN1 antibody and peripheral B cells were also evaluated at baseline, 2 days, and 6 months after the rituximab regimen.

Results

Two patients with anti–CNTN1 antibodies were enrolled. Both patients had neurological symptoms including muscle weakness, tremor, sensory ataxia, numbness and mild nephrotic symptoms. In the field of neurological symptoms, sensory ataxia markedly improved, and the titer of anti-CNTN1 antibody as well as CD19+ B cells decreased only two days following low-dose rituximab treatment. Other neurological symptoms improved within two weeks of rituximab treatment. At the 6-month follow-up, all neurological symptoms steadily improved with steroid reduction, and both the anti-CNTN1 antibody titer and CD19+ B cells steadily decreased. No adverse events were observed after this single low-dose rituximab treatment.

Conclusions

We confirmed the clinical efficacy of low-dose rituximab by B cell depletion in autoimmune nodopathy with anti-CNTN1 antibody. This rapid and long-lasting response suggests that low-dose rituximab is a promising option for anti-CNTN1 nodopathy.