Ofatumumab for refractory opsoclonus-myoclonus syndrome following treatment of neuroblastoma

Monocentric retrospective clinical outcome in a group of 13 patients with opsoclonus myoclonus syndrome, proposal of diagnostic algorithm and review of the literature

BACKGROUND

Dancing eye syndrome or opsoclonus-myoclonus syndrome (OMS) is a very rare disease (incidence <1/5,000,000 per year), which is more prevalent in young children. Although it is not usually a cause of mortality, the aftermaths are not rare.

METHODS

We performed an observational retrospective review of children diagnosed with OMS in our neuropediatric department from 1996 to 2020, with the objective of assessing the prognostic value of initial clinical features. All medical data from diagnosis to last follow-up were reviewed. We defined unfavorable evolution of OMS as persistence or worsening of symptoms. Subsequently, based on a literature review, our results and experience, a diagnostic algorithm was developed.

RESULTS

A total of 13 OMS patients were included: 61.5% were male (n = 8), median age at diagnosis was 18 months (IR = 76), median treatment delay was 14 days (IR = 146) and OMS score at onset was 8 (IR = 11). The most frequent etiologies were neuroblastoma-associated and idiopathic OMS (38.46%; n = 5) of the patients, followed by post-infectious OMS (n = 3). All the patients were treated with corticosteroids, five required a surgical intervention (neuroblastoma group), and three required adjunctive immune therapy (immunoglobulins, cyclophosphamide and/or rituximab). We detected neurodevelopmental disorders in 38.46% (n = 5) of the patients, mainly attention deficit (n = 4), and persistent sleep disturbances (n = 4). The median OMS score at the end of follow-up was 1 (IR = 3). An important diagnostic delay, OMS score of ≥10 and age >1 year at onset may correlate with a higher risk of aftermaths. We detected a better prognosis in the post-infectious OMS, with full recovery occurring in 2/3 of patients.

CONCLUSIONS

Early clinical suspicion is key to guarantee maximum response of treatment.

The Treatment of Opsoclonus-Myoclonus Syndrome Secondary to Neuroblastic Tumours-Single-Centre Experience and Literature Review

Background and Objectives: The opsoclonus-myoclonus syndrome (OMS) is characterised by opsoclons, myoclons and impaired balance, often concomitant with sleep disorder and behavioural difficulties. The symptoms develop as a result of autoimmune response triggered by a neuroblastic tumour (NT). OMS can also develop secondarily to a viral infection or as an immune response triggered by an unknown agent. This leads to the activation of B- and T-cells, which produce and release autoantibodies or cytokines directly within the central nervous system (CNS), thus damaging the neurons within the cerebellum and the brain stem. The available OMS treatments aim at decreasing lymphocyte, cytokine and autoantibody production or accelerating the utilisation of the latter. Another treatment option for OMS involves using cytostatic agents, which damage T- and B-cells causing their depletion and impaired function, which reduces their ability to produce antibodies and cytokines. Materials and Methods: We present a single-centre experience in treating OMS secondary to NT in 7 children. Results: The combined treatment with cyclophosphamide plus dexamethasone resulted in a complete resolution of OMS symptoms in 4 children, and a significant improvement in the 3 children. Two of them periodically present hyperactivity, and one girl requires an additional support at school due to special educational needs (SEN). Conclusions: NT resection does not resolve OMS in children with OMS secondary to NT. The combined treatment with dexamethasone plus cyclophosphamide seems to be an effective treatment of OMS.

Antineuronal Nuclear Autoantibody Type 1/Anti-Hu-Associated Opsoclonus Myoclonus and Epilepsia Partialis Continua: Case Report and Literature Review

BACKGROUND

Opsoclonus-myoclonus syndrome is a rare clinical condition that has been associated with neuroblastoma. There are few reported examples of ANNA-1/anti-Hu antibodies in children with neuroblastoma and opsoclonus-myoclonus, all in children aged less than three years of age.

METHODS

We describe the new onset of focal seizures without alteration of consciousness and opsoclonus-myoclonus in an 11-year-old girl with ANNA-1/anti-Hu positivity and a paraspinal ganglioneuroblastoma. A systematic review of the literature of children with ANNA-1/anti-Hu positivity and malignancy was also performed.

RESULTS

Fourteen patients were identified, eight of whom had opsoclonus-myoclonus. Although epilepsia partialis continua has been described in association with several neuronal autoantibodies, association with ANNA-1/anti-Hu has not been reported.

CONCLUSIONS

We describe epilepsia partialis continua in a child with ANNA-1/anti-Hu antibodies and neuroblastoma. Testing for antineuronal antibodies should be considered in children presenting with either opsoclonus-myoclonus or epilepsia partialis continua.

Trends and tenets in relapsing and progressive opsoclonus-myoclonus syndrome

Despite advances in inducing remission in pediatric opsoclonus-myoclonus syndrome (OMS), relapse remains a challenge. By definition, relapse is not a characteristic of monophasic OMS, but occurs at any time in the course of multiphasic OMS. Due to variability and heterogeneity, patients are best approached and treated on a case-by-case basis, using precepts derived from clinical and scientific studies. Treatment of provocations, such as infection or immunotherapy tapering, is the short-term goal, but discovering unresolved neuroinflammation and re-configuring disease-modifying agents is crucial in the long-term. The working hypothesis is that much of the injury in OMS results from neuroinflammation involving dysregulated B cells, which may cause loss of tolerance and autoantibody production. Biomarkers of disease activity include cerebrospinal fluid (CSF) B cell frequency, oligoclonal bands (OCB), B cell attractants (CXCL13) and activating factors (BAFF). Measuring these markers comprises modern detection and characterization of neuroinflammation or verifies 'no evidence of disease activity'. The decision making process is three-tiered: deciding if the relapse is bone fide, identifying its etiology, and formulating a therapeutic plan. Relapsing-remitting OMS is treatable, and combination multimodal/multi-mechanistic immunotherapy is improving the outcome. However, some patients progress to a refractory state with cognitive impairment and disability from failure to go into remission, multiple relapses, or more aggressive disease. This report provides new insights on underappreciated risks and pitfalls inherent in relapse, pro-active efforts to avoid progression, the need for early and sufficient treatment beyond corticosteroids and immunoglobulins, and utilization of disease activity biomarkers to identify high-risk patients and safely withdraw immunotherapy.

Anti-B-Cell Therapies in Autoimmune Neurological Diseases: Rationale and Efficacy Trials

B cells have an ever-increasing role in the etiopathology of a number of autoimmune neurological disorders, acting as antibody-producing cells and, most importantly, as sensors, coordinators, and regulators of the immune response. B cells, among other functions, regulate the T-cell activation process through their participation in antigen presentation and production of cytokines. The availability of monoclonal antibodies or fusion proteins against B-cell surface molecules or B-cell trophic factors bestows a rational approach for treating autoimmune neurological disorders, even when T cells are the main effector cells. This review summarizes basic aspects of B-cell biology, discusses the role(s) of B cells in neurological autoimmunity, and presents anti-B-cell drugs that are either currently on the market or are expected to be available in the near future for treating neurological autoimmune disorders.