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

Therapeutic potentials of adoptive cell therapy in immune-mediated neuropathy

Immune-mediated neuropathy (IMN) is a group of heterogenous neuropathies caused by intricate autoimmune responses. For now, known mechanisms of different IMN subtypes involve the production of autoantibodies, complement activation, enhanced inflammation and subsequent axonal/demyelinating nerve damages. Recent therapeutic studies mainly focus on specific antibodies and small molecule inhibitors previously approved in rheumatoid diseases. Initial strategies based on the pathophysiologic features of IMN should be explored. Adoptive cell therapy (ACT) refers to the emerging immunotherapies in which circulating immunocytes are collected from peripheral blood and modified with killing and immunomodulatory capacities. It consists of chimeric antigen receptor-T cell therapy, T cell receptor-engineered T cell, CAR-Natural killer cell therapy, and others. In the last decade, ACT has demonstrated extraordinary potentials in treating cancers, infectious diseases and autoimmune diseases. Versatile combinations of targets, chimeric domains and effector cells greatly empower ACT to treat complicated immune disorders. In this review, we summarized the advances of ACT and envisioned suitable strategies for different IMN subtypes.

Recurrent CNTN1 antibody-positive nodopathy: a case report and literature review

Background

Contactin-1 (CNTN1) antibody-positive nodopathy is rare and exhibits distinct clinical symptoms such as tremors and ataxia. However, the mechanisms of these symptoms and the characteristics of the cerebral spinal fluid (CSF) remain unknown.

Case presentation

Here, we report a case of recurrent CNTN1 antibody-positive nodopathy. Initially, a 45-year-old woman experiencing numbness in the upper limbs and weakness in the lower limbs was diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Eleven years later, her symptoms worsened, and she began to experience tremors and ataxia. Tests for serum CNTN1, GT1a, and GQ1b antibodies returned positive. Subsequently, she was diagnosed with CNTN1 antibody-positive nodopathy and underwent plasmapheresis therapy, although the treatment's efficacy was limited. To gain a deeper understanding of the disease, we conducted a comprehensive literature review, identifying 52 cases of CNTN1 antibody-positive nodopathy to date, with a tremor prevalence of 26.9%. Additionally, we found that the average CSF protein level in CNTN1 antibody-positive nodopathy was 2.57 g/L, with 87% of patients exhibiting a CSF protein level above 1.5 g/L.

Conclusion

We present a rare case of recurrent CNTN1 antibody-positive nodopathy. Our findings indicate a high prevalence of tremor (26.9%) and elevated CSF protein levels among patients with CNTN1 antibody-positive nodopathy.

Autoimmune central nervous system disorders: Antibody testing and its clinical utility

A rapidly expanding repertoire of neural antibody biomarkers exists for autoimmune central nervous system (CNS) disorders. Following clinical recognition of an autoimmune CNS disorder, the detection of a neural antibody facilitates diagnosis and informs prognosis and management. This review considers the phenotypes, diagnostic assay methodologies, and clinical utility of neural antibodies in autoimmune CNS disorders. Autoimmune CNS disorders may present with a diverse range of clinical features. Clinical phenotype should inform the neural antibodies selected for testing via the use of phenotype-specific panels. Both serum and cerebrospinal fluid (CSF) are preferred in the vast majority of cases but for some analytes either CSF (e.g. N-methyl-D-aspartate receptor [NMDA-R] IgG) or serum (e.g. aquaporin-4 [AQP4] IgG) specimens may be preferred. Screening using 2 methods is recommended for most analytes, particularly paraneoplastic antibodies. We utilize murine tissue-based indirect immunofluorescence assay (TIFA) with subsequent confirmatory protein-specific testing. The cellular location of the target antigen informs choice of confirmatory diagnostic assay (e.g. blot for intracellular antigens such as Hu; cell-based assay for cell surface targets such as leucine-rich glioma inactivated 1 [LGI1]). Titers of positive results have limited diagnostic utility with the exception of glutamic acid decarboxylase (GAD) 65 IgG autoimmunity, which is associated with neurological disease at higher values. While novel antibodies are typically discovered using established techniques such as TIFA and immunoprecipitation-mass spectrometry, more recent high-throughput molecular technologies (such as protein microarray and phage-display immunoprecipitation sequencing) may expedite the process of antibody discovery. Individual neural antibodies inform the clinician regarding the clinical associations, oncological risk stratification and tumor histology, the likely prognosis, and immunotherapy choice. In the era of neural antibody biomarkers for autoimmune CNS disorders, access to appropriate laboratory assays for neural antibodies is of critical importance in the diagnosis and management of these disorders.

Autoimmune nodopathy with anti-contactin 1 antibody characterized by cerebellar dysarthria: a case report and literature review

Background

Autoimmune nodopathy (AN) has emerged as a novel diagnostic category that is pathologically different from classic chronic inflammatory demyelinating polyneuropathy. Clinical manifestations of AN include sensory or motor neuropathies, sensory ataxia, tremor, and cranial nerve involvement. AN with a serum-positive contactin-1 (CNTN1) antibody usually results in peripheral nerve demyelination. In this study, we reported a rare case of AN with CNTN1 antibodies characterized by the presence of CNTN1 antibodies in both serum and cerebrospinal fluid, which is associated with cerebellar dysarthria.

Methods

A 25-year-old man was admitted to our hospital due to progressive dysarthria with limb tremors. The patient was initially diagnosed with peripheral neuropathy at a local hospital. Three years after onset, he was admitted to our hospital due to dysarthria, apparent limb tremor, and limb weakness. At that time, he was diagnosed with spinocerebellar ataxia. Eight years post-onset, during his second admission, his condition had notably deteriorated. His dysarthria had evolved to typical distinctive cerebellar characteristics, such as tremor, loud voice, stress, and interrupted articulation. Additionally, he experienced further progression in limb weakness and developed muscle atrophy in the distal limbs. Magnetic resonance imaging (MRI), nerve conduction studies (NCS), and autoimmune antibody tests were performed.

Results

The results of the NCS suggested severe demyelination and even axonal damage to the peripheral nerves. MRI scans revealed diffuse thickening of bilateral cervical nerve roots, lumbosacral nerve roots, cauda equina nerve, and multiple intercostal nerve root sheath cysts. Furthermore, anti-CNTN1 antibody titers were 1:10 in the cerebrospinal fluid (CSF) and 1:100 in the serum. After one round of rituximab treatment, the patient showed significant improvement in limb weakness and dysarthria, and the CSF antibodies turned negative.

Conclusion

Apart from peripheral neuropathies, cerebellar dysarthria (central nervous system involvement) should not be ignored in AN patients with CNTN1 antibodies.

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.

Anti-rituximab antibodies in patients with refractory autoimmune nodopathy with anti-neurofascin-155 antibody

Background

Recent studies have reported that similar to other IgG4 autoimmune diseases, such as muscle-specific kinase antibody-associated myasthenia gravis, most anti-neurofascin-155 (anti-NF155) nodopathies respond well to rituximab treatment, regardless of the dosage. However, there are still a few patients for which rituximab is ineffective for unknown reasons. Currently, there are no studies on the mechanism of ineffective treatment with rituximab.

Methods

A 33-year-old Chinese man presenting with numbness, tremor, and muscle weakness for 4 years was recruited for this study. Anti-NF155 antibodies were identified by cell-based assay and confirmed by immunofluorescence assay on teased fibers. The anti-NF155 immunoglobulin (IgG) subclasses were also detected by immunofluorescence assay. Anti-rituximab antibodies (ARAs) were quantitatively analyzed using enzyme-linked immunosorbent assay (ELISA), and peripheral B cell counts were determined by flow cytometry.

Results

The patient exhibited anti-NF155 IgG4-antibody positivity. After the first round of rituximab infusion, the patient showed stratified outcomes with improvements in numbness, muscle weakness and ambulation. However, after three rounds of rituximab infusion, the patient’s symptoms deteriorated, and the numbness, tremor and muscle weakness returned. No obvious improvement was found after plasma exchange and another round of rituximab treatment. 14 days after the last treatment with rituximab, ARAs were detected. And the titers gradually decreased on day 28 and 60 but remained higher than normal. Peripheral CD19+ B cell counts were less than 1% within the 2-month period following the final rituximab administration.

Conclusions

In this study, ARAs presented in a patient with anti-NF155 nodopathy undergoing rituximab treatment and showed an unfavorable impact on rituximab efficacy. This is the first case to report the occurrence of ARAs in patients with anti-NF155 antibodies. We suggest that ARAs should be tested early during the initial intervention, especially in patients who respond poorly to rituximab treatment. In addition, we believe it is necessary to investigate the association between ARAs and B cell counts, their effect on clinical efficacy, and their potential adverse reactions in a larger cohort of patients with anti-NF155 nodopathy.