Targeting IL-6 receptor in the treatment of neuromyelitis optica spectrum: a review of emerging treatment options

Research progress on pathogenesis and clinical treatment of neuromyelitis optica spectrum disorders (NMOSDs)

Neuromyelitis optica spectrum disorders (NMOSDs) are characteristically referred to as various central nervous system (CNS)-based inflammatory and astrocytopathic disorders, often manifested by the axonal damage and immune-mediated demyelination targeting optic nerves and the spinal cord. This review article presents a detailed view of the etiology, pathogenesis, and prescribed treatment options for NMOSD therapy. Initially, we present the epidemiology of NMOSDs, highlighting the geographical and ethnical differences in the incidence and prevalence rates of NMOSDs. Further, the etiology and pathogenesis of NMOSDs are emphasized, providing discussions relevant to various genetic, environmental, and immune-related factors. Finally, the applied treatment strategies for curing NMOSD are discussed, exploring the perspectives for developing emergent innovative treatment strategies.

Satralizumab, Novel Interleukine-6 Inhibitor for Preventing Descending Thoracic Aorta Aneurysm Development

BACKGROUND

Descending thoracic aorta aneurysm (dTAA) has increasing incidence and, if left untreated, could lead to death. There is not any study of satralizumab treatment for preventing dTAA formation and progression.

MATERIALS AND METHODS

Forty male 10-week-old Rattus norvegicus were enrolled in the experiment. They were divided into four equal groups: dTAA treated with saline (dTAA-P) and dTAA treated with satralizumab (dTAA-S). One of the control groups was treated with saline (C-P), and the other was treated with satralizumab (C-S). Satralizumab and saline were used once every 2 weeks, subcutaneously 120 mg for 4 weeks. dTA diameter was measured at days 0, 3, 7, 14, 21, and 28.

RESULTS

IL-6 level was measured on the 7th day that showed significantly increased IL-6 serum level in dTAA-P rats compared to C-P. Maximal dTA diameter (%MAD) was obtained at day 14, which was scientifically matched to the aorta aneurysm definition (>50% increase in diameter). From the seventh day, a significant difference in %MAD was observed between dTAA-P and dTAA-S groups. However, the %MAD of these two groups was significantly higher than control groups till the end of the 28th day.

CONCLUSION

Using an IL-6 inhibitor agent to prevent dTAA formation and progression showed promising results. It suggests that using the IL-6 inhibitors in susceptible persons can be considered a lifesaving therapeutic approach.

Genomic Multiple Sclerosis Risk Variants Modulate the Expression of the ANKRD55-IL6ST Gene Region in Immature Dendritic Cells

Intronic single-nucleotide polymorphisms (SNPs) in the ANKRD55 gene are associated with the risk for multiple sclerosis (MS) and rheumatoid arthritis by genome-wide association studies (GWAS). The risk alleles have been linked to higher expression levels of ANKRD55 and the neighboring IL6ST (gp130) gene in CD4+ T lymphocytes of healthy controls. The biological function of ANKRD55, its role in the immune system, and cellular sources of expression other than lymphocytes remain uncharacterized. Here, we show that monocytes gain capacity to express ANKRD55 during differentiation in immature monocyte-derived dendritic cells (moDCs) in the presence of interleukin (IL)-4/granulocyte-macrophage colony-stimulating factor (GM-CSF). ANKRD55 expression levels are further enhanced by retinoic acid agonist AM580 but downregulated following maturation with interferon (IFN)-γ and lipopolysaccharide (LPS). ANKRD55 was detected in the nucleus of moDC in nuclear speckles. We also analyzed the adjacent IL6ST, IL31RA, and SLC38A9 genes. Of note, in healthy controls, MS risk SNP genotype influenced ANKRD55 and IL6ST expression in immature moDC in opposite directions to that in CD4+ T cells. This effect was stronger for a partially correlated SNP, rs13186299, that is located, similar to the main MS risk SNPs, in an ANKRD55 intron. Upon analysis in MS patients, the main GWAS MS risk SNP rs7731626 was associated with ANKRD55 expression levels in CD4+ T cells. MoDC-specific ANKRD55 and IL6ST mRNA levels showed significant differences according to the clinical form of the disease, but, in contrast to healthy controls, were not influenced by genotype. We also measured serum sgp130 levels, which were found to be higher in homozygotes of the protective allele of rs7731626. Our study characterizes ANKRD55 expression in moDC and indicates monocyte-to-dendritic cell (Mo-DC) differentiation as a process potentially influenced by MS risk SNPs.

Interleukin-6: evolving role in the management of neuropathic pain in neuroimmunological disorders

Background

Neuropathic pain in neuroimmunological disorders refers to pain caused by a lesion or disease of the somatosensory system such as multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD). MS and NMOSD are autoimmune disorders of the central nervous system, and ≥ 50% of patients with these disorders experience chronic neuropathic pain. The currently available medications for the management of neuropathic pain have limited effectiveness in patients with MS and NMOSD, and there is an unmet medical need to identify novel therapies for the management of chronic neuropathic pain in these patients. In this review article, we summarize the role of interleukin-6 (IL-6) in the pathogenesis of MS and NMOSD and the ameliorative effects of anti–IL-6 therapies in mouse models of experimental autoimmune encephalomyelitis (EAE).

Main body

Intraperitoneal injection of MR16-1, an anti–IL-6 receptor (IL-6R) antibody, reduced mechanical allodynia and spontaneous pain in EAE mice, which was attributed to a reduction in microglial activation and inhibition of the descending pain inhibitory system. The effect of anti–IL-6 therapies in ameliorating neuropathic pain in the clinical setting is controversial; a reduction in pain intensity has been reported with an anti–IL-6 antibody in four studies, namely a case report, a pilot study, a retrospective observational study, and a case series. Pain intensity was evaluated using a numerical rating scale (NRS), with a lower score indicating lesser pain. A reduction in the NRS score was reported in all four studies. However, in two randomized controlled trials of another anti–IL-6R antibody, the change in the visual analog scale pain score was not statistically significantly different when compared with placebo. This was attributed to the low mean pain score at baseline in both the trials and the concomitant use of medications for pain in one of the trials, which may have masked the effects of the anti–IL-6R antibody on neuropathic pain.

Conclusion

Thus, anti–IL-6 therapies might have a potential to reduce neuropathic pain, but further investigations are warranted to clarify the effect of inhibition of IL-6 signaling on neuropathic pain associated with MS and NMOSD.

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.

New progress in the treatment of neuromyelitis optica spectrum disorder with monoclonal antibodies (Review)

Neuromyelitis optica spectrum disorder (NMOSD) is a group of immune-mediated inflammatory demyelinating diseases mainly affecting the central nervous system. It is characterized by high risk of relapse and progression to disability. The frequent recurrences of neuromyelitis optica spectrum disorder often exacerbate the neurological dysfunction and severely affect the patient's quality of life. Conventional treatments for neuromyelitis optica spectrum disorder, including acute treatment and sequential therapy, aim to decrease the degree of disability and recurrences. In recent years, new monoclonal antibodies have yielded encouraging results. The present review discusses the research status and recent progress in the treatment of NMOSD with monoclonal antibodies.

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.

Recent progress in maintenance treatment of neuromyelitis optica spectrum disorder

Background

Treatment of neuromyelitis optica spectrum disorder (NMOSD) has so far been based on retrospective case series. The results of six randomized clinical trials including five different monoclonal antibodies targeting four molecules and three distinct pathophysiological pathways have recently been published.

Methods

Literature search on clinical trials and case studies in NMOSD up to July 10. 2020.

Results

We review mechanism of action, efficacy and side effects, and consequences for reproductive health from traditional immunosuppressants and monoclonal antibodies including rituximab, inebilizumab, eculizumab, tocilizumab and satralizumab.

Conclusion

In NMOSD patients with antibodies against aquaporin 4, monoclonal antibodies that deplete B cells (rituximab and inebilizumab) or interfere with interleukin 6 signaling (tocilizumab and satralizumab) or complement activation (eculizumab) have superior efficacy compared to placebo. Tocilizumab and rituximab were also superior to azathioprine in head-to-head studies. Rituximab, tocilizumab and to some extent eculizumab have well-known safety profiles for other inflammatory diseases, and rituximab and azathioprine may be safe during pregnancy.