Central Nervous System Demyelination Associated With Immune Checkpoint Inhibitors: Review of the Literature

Neurological Immune-Related Adverse Events Induced by Immune Checkpoint Inhibitors

The use of immune checkpoint inhibitors (ICIs) for the treatment of various advanced and aggressive types of malignancy has significantly increased both survival and long-term remission rates. ICIs block crucial inhibitory pathways of the immune system, in order to trigger an aggravated immune response against the tumor. However, this enhanced immune activation leads to the development of numerous immune-related adverse events (irAEs), which may affect any system. Although severe neurological irAEs are relatively rare, they carry a high disability burden, and they can be potentially life-threatening. Therefore, clinicians must be alert and act promptly when individuals receiving ICIs present with new-onset neurological symptoms. In this narrative review, we have collected all the currently available data regarding the epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of post-ICI neurological irAEs. This review aims to raise physicians' awareness, enrich their knowledge regarding disease pathogenesis, and guide them through the diagnosis and management of post-ICI neurological irAEs.

Central nervous system adverse events of immune checkpoint inhibitors

PURPOSE OF REVIEW

Immune checkpoint inhibitors (ICI) may trigger immune-related adverse events which rarely affect the central nervous system (CNS-irAEs). Over the past few years, cumulative data have led to the characterization of well defined syndromes with distinct cancer and antibody associations as well as different outcomes.

RECENT FINDINGS

The most frequent CNS-irAE is encephalitis, which includes three main groups: meningoencephalitis, a nonfocal syndrome usually responsive to corticosteroids; limbic encephalitis, associated with high-risk paraneoplastic neurological syndromes (PNS) antibodies (e.g. anti-Hu, anti-Ma2) and neuroendocrine cancers, characterized by poor treatment response and outcomes; and cerebellar ataxia, with variable outcomes (worse when high-risk PNS antibodies are detected). Additionally, a diffuse encephalopathy without inflammatory findings, with poor response to corticosteroids and high mortality has been described. The spectrum of CNS-irAEs also includes meningitis, myelitis, and rarer presentations. A subset of CNS-irAEs (i.e. limbic encephalitis and/or rapidly progressive cerebellar ataxia) is undistinguishable from ICI-naïve PNS.

SUMMARY

The clinical and outcomes diversity of CNS-irAEs suggests different pathogenic mechanisms, which need to be understood to establish more effective and specific treatment modalities. It is crucial to identify biomarkers able to predict which patients will experience severe CNS-irAEs, to anticipate their diagnosis, and to predict long-term outcomes.

Neuromyelitis optica associated with the use of Atezolizumab in a patient with advanced lung adenocarcinoma

Immune checkpoint inhibitors (ICIs) are a pharmacological group increasingly used in Oncology and Hematology. These treatments can lead to autoimmune complications, with neurological conditions, especially central nervous system (CNS) involvement, being rare. We describe a case of seropositive neuromyelitis optica in a patient with locally advanced lung adenocarcinoma treated with Atezolizumab.

Neurological Adverse Events Related to Immune Checkpoint Inhibitors: A Practical Review

The increasing use of immune checkpoint inhibitors (ICI) in cancer therapy has brought attention to their associated neurotoxicities, termed neurological immune-related adverse events (n-irAEs). Despite their relatively rare incidence, n-irAEs pose a significant risk, potentially leading to severe, long-lasting disabilities or even fatal outcomes. This narrative review aims to provide a comprehensive overview of n-irAEs, focusing on their recognition and management. The review addresses a spectrum of n-irAEs, encompassing myositis, myasthenia gravis, various neuropathies, and central nervous system complications, such as encephalitis, meningitis, and demyelinating diseases. The key features of n-irAEs are emphasized in this review, including their early onset after initiation of ICIs, potential association with non-neurological irAEs and/or concurrent oncological response, the significance of ruling out other etiologies, and the expected improvement upon discontinuation of ICIs and/or immunosuppression. Furthermore, this review delves into considerations for ICI re-challenge and the intricate nature of n-irAEs within the context of pre-existing autoimmune and paraneoplastic syndromes. It underscores the importance of a multidisciplinary approach to diagnosis and treatment, highlighting the pivotal role of severity grading in guiding treatment decisions.

Altered immune co-inhibitory receptor expression and correlation of LAG-3 expression to disease severity in NMOSD

Co-inhibitory receptors (CIR)s regulate T cell-mediated immune responses and growing evidence links co-inhibitory receptors to the progression of neuroimmunological diseases. We studied the expression levels of CIRs: TIM-3, TIGIT, PD-1 and LAG-3 in the peripheral blood mononuclear cells (PBMCs) of 30 patients with Neuromyelitis optica spectrum disorder (NMOSD), 11 Multiple sclerosis (MS) patients and 31 Healthy controls (HC). We found that the mRNA expression levels of TIM-3 were significantly increased in NMOSD compared with HC, and increased LAG-3 surface protein expression was also observed on T-cells of NMOSD patients. Moreover, we observed a negative correlation between LAG-3 expression and disease severity in NMOSD. Our findings suggest a protective effect of LAG-3 in the setting of NMOSD, and that the differential expression of CIRs observed in this study may play a role in the pathological process of NMOSD.

Prevalence of neuromyelitis optica spectrum disorder in the United States

BACKGROUND

Neuromyelitis optic spectrum disorder (NMOSD) is a rare demyelinating, autoimmune disease and the burden in United States is not well characterized.

OBJECTIVE

The objective of this study was to determine the 2022 US prevalence of NMOSD.

METHODS

We constructed a cross-sectional study using aggregated electronic health record data for 25.7 million patients who had a 2022 clinical encounter. The data originated from the TriNetX US Collaborative Network of 55 healthcare organizations that span all 50 states. NMOSD prevalence was determined by querying for age-interval, sex, and race combinations, with direct standardization to the 2022 US Census data.

RESULTS

There were 1772 NMOSD patients among 25,743,039 patients for a prevalence of 6.88/100,000. Prevalence was the highest in Blacks (12.99/100,000) who represented 27.7% of NMOSD patients, then Asians (9.41/100,000and Whites (5.58/100,000). Among females, the prevalence of NMOSD was 9.48/100,000, and Black and Asian females had a 2.65- and 1.94-times higher prevalence than White females. In males, the prevalence of NMOSD was 3.52/100,000 and it did not differ by race. We observed a 3/5:1 female-to-male ratio in NMOSD. The age- and sex-adjusted 2022 estimate of persons with NMOSD in the United States was 15,413 females and 6233 males.

CONCLUSION

We estimate that there were near 22,000 Americans living with NMOSD in 2022.

Neurologic manifestations of autoimmunity with immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) are cancer immunotherapies that enhance the body's own immune system to treat cancer. ICI treatment, however, can cause immune-related adverse events (irAEs) that can affect any organ, resulting in significant morbidity and mortality. Neurologic irAEs (nirAEs) are rare and can affect the peripheral nervous system more commonly than the central nervous system. Treatment is dependent on the severity of the neurologic manifestations and often includs discontinuation of the ICI and initiation of steroid therapy as the first line; other treatments have also been used. NirAEs and cardiac irAEs have higher fatality rates underlying the importance of early recognition and appropriate management. This chapter reviews the clinical manifestations of neurologic immune-related adverse events associated with ICI treatment as well as diagnostic and therapeutic modalities.

Effects of High Efficacy Multiple Sclerosis Disease Modifying Drugs on the Immune Synapse: A Systematic Review

BACKGROUND

Co-signaling and adhesion molecules are important elements for creating immune synapses between T lymphocytes and antigen-presenting cells; they positively or negatively regulate the interaction between a T cell receptor with its cognate antigen, presented by the major histocompatibility complex.

OBJECTIVES

We conducted a systematic review on the effects of High Efficacy Disease Modifying Drugs (HEDMDs) for Multiple Sclerosis (MS) on the co-signaling and adhesion molecules that form the immune synapse.

METHODS

We searched EMBASE, MEDLINE, and other sources to identify clinical or preclinical reports on the effects of HEDMDs on co-signaling and adhesion molecules that participate in the formation of immune synapses in patients with MS or other autoimmune disorders. We included reports on cladribine tablets, anti- CD20 monoclonal antibodies, S1P modulators, inhibitors of Bruton's Tyrosine Kinase, and natalizumab.

RESULTS

In 56 eligible reports among 7340 total publications, limited relevant evidence was uncovered. Not all co-signaling and adhesion molecules have been studied in relation to every HEDMD, with more data being available on the anti-CD20 monoclonal antibodies (that affect CD80, CD86, GITR and TIGIT), cladribine tablets (affecting CD28, CD40, ICAM-1, LFA-1) and the S1P modulators (affecting CD86, ICAM-1 and LFA-1) and less on Natalizumab (affecting CD80, CD86, CD40, LFA-1, VLA-4) and Alemtuzumab (affecting GITR and CTLA-4).

CONCLUSION

The puzzle of HEDMD effects on the immune synapse is far from complete. The available evidence suggests that distinguishing differences exist between drugs and are worth pursuing further.

Immune Checkpoint Inhibitors in Patients with Pre-existing Neurologic Autoimmune Disorders

PURPOSE OF REVIEW

The use of immune checkpoint inhibitors (ICIs) for oncologic indications is associated with immune-related adverse events (irAEs). Patients with pre-existing autoimmune diseases are at increased risk of irAEs and have largely been excluded from clinical trials of ICIs. Therefore, there is limited data on the safety of safety of ICIs in patients with pre-existing neurologic autoimmune diseases (nAIDs) such as myasthenia gravis and multiple sclerosis. This review aims to synthesize the literature on the post-marketing experience with ICI in patients with pre-existing nAID and to discuss possible strategies for mitigating the risk of post-ICI nAID relapses.

RECENT FINDINGS

Patients with pre-existing myasthenia gravis (MG), myositis, and paraneoplastic encephalitis appear highly susceptible to neurologic relapses of their underlying neurologic disorder following ICI initiation; these relapses can cause considerable morbidity and mortality. In patients with multiple sclerosis (MS), the risk and severity of MS relapses following ICI appears to be relatively lower compared to MG. Preliminary evidence suggests that older MS patients with no recent focal neuroinflammatory activity may be safely treated with ICI. Among the several case reports of ICI in patients with a history of Guillain-Barre syndrome (GBS), neurologic worsening was only recorded in one patient who was in the acute phase of GBS at the time of ICI start. Initiating an ICI in a patient with pre-existing nAID involves a complex risk-benefit discussion between the patient, their oncologist, and neurologist. Relevant issues to consider before ICI include the choice of disease-modifying therapy for nAID (if any) and strategies for promptly identifying and managing nAID relapses should they occur. Currently, the literature consists mainly of case reports and case series, subject to publication bias. Prospective studies of ICI in patients with nAID are needed to improve the level of evidence.

Regulation of the programmed cell death protein 1/programmed cell death ligand 1 axis in relapsing-remitting multiple sclerosis

The programmed cell death protein 1/programmed cell death ligand 1 axis plays an important role in the adaptive immune system and has influence on neoplastic and inflammatory diseases, while its role in multiple sclerosis is unclear. Here, we aimed to analyse expression patterns of programmed cell death protein 1 and programmed cell death ligand 1 on peripheral blood mononuclear cells and their soluble variants in multiple sclerosis patients and controls, to determine their correlation with clinical disability and disease activity. In a cross-sectional study, we performed in-depth flow cytometric immunophenotyping of peripheral blood mononuclear cells and analysed soluble programmed cell death protein 1 and programmed cell death ligand 1 serum levels in patients with relapsing-remitting multiple sclerosis and controls. In comparison to control subjects, relapsing-remitting multiple sclerosis patients displayed distinct cellular programmed cell death protein 1/programmed cell death ligand 1 expression patterns in immune cell subsets and increased soluble programmed cell death ligand 1 levels, which correlated with clinical measures of disability and MRI activity over time. This study extends our knowledge of how programmed cell death protein 1 and programmed cell death ligand 1 are expressed in the membranes of patients with relapsing-remitting multiple sclerosis and describes for the first time the elevation of soluble programmed cell death ligand 1 in the blood of multiple sclerosis patients. The distinct expression pattern of membrane-bound programmed cell death protein 1 and programmed cell death ligand 1 and the correlation between soluble programmed cell death ligand 1, membrane-bound programmed cell death ligand 1, disease and clinical factors may offer therapeutic potential in the setting of multiple sclerosis and might improve future diagnosis and clinical decision-making.

Neurologic Complications of Cancer Immunotherapy

Immunotherapy has revolutionized cancer treatment over the past decade. As it is increasingly introduced into routine clinical practice, immune-related complications have become more frequent. Accurate diagnosis and treatment are essential, with the goal of reduced patient morbidity. This review aims to discuss the various clinical manifestations, diagnosis, treatments, and prognosis of neurologic complications associated with the use of immune checkpoint inhibitors, adoptive T-cell therapies, and T-cell redirecting therapies. We also outline a suggested clinical approach related to the clinical use of these agents.

Identification of the shared gene signatures and molecular mechanisms between multiple sclerosis and non-small cell lung cancer

Introduction

The association between multiple sclerosis (MS) and non-small cell lung cancer (NSCLC) has been the subject of investigation in clinical cohorts, yet the molecular mechanisms underpinning this relationship remain incompletely understood. To address this, our study aimed to identify shared genetic signatures, shared local immune microenvironment, and molecular mechanisms between MS and NSCLC.

Methods

We selected multiple Gene Expression Omnibus (GEO) datasets, including GSE19188, GSE214334, GSE199460, and GSE148071, to obtain gene expression levels and clinical information from patients or mice with MS and NSCLC. We employed Weighted Gene Co-expression Network Analysis (WGCNA) to investigate co-expression networks linked to MS and NSCLC and used single-cell RNA sequencing (scRNA-seq) analysis to explore the local immune microenvironment of MS and NSCLC and identify possible shared components.

Results

Our analysis identified the most significant shared gene in MS and NSCLC, phosphodiesterase 4A (PDE4A), and we analyzed its expression in NSCLC patients and its impact on patient prognosis, as well as its molecular mechanism. Our results demonstrated that high expression of PDE4A was associated with poor prognoses in NSCLC patients, and Gene Set Enrichment Analysis (GSEA) revealed that PDE4A is involved in immune-related pathways and has a significant regulatory effect on human immune responses. We further observed that PDE4A was closely linked to the sensitivity of several chemotherapy drugs.

Conclusion

Given the limitation of studies investigating the molecular mechanisms underlying the correlation between MS and NSCLC, our findings suggest that there are shared pathogenic processes and molecular mechanisms between these two diseases and that PDE4A represents a potential therapeutic target and immune-related biomarker for patients with both MS and NSCLC.

Neurological adverse events of immune checkpoint inhibitors: An update of clinical presentations, diagnosis, and management

The use of immune checkpoint inhibitors (ICIs) has represented a major advance in cancer treatment. By enhancing endogenous immune responses to destroy cancer cells, ICIs can cause immune-related adverse events (irAEs), with possible involvement of any organ system. IrAEs are frequent, particularly those involving the skin or the endocrine system, and usually completely reversible after temporary immunosuppression, while neurological irAEs (n-irAEs) are relatively rare, often severe, and they carry a considerable risk of mortality and long-term disability. They usually affect the peripheral nervous system, mainly manifesting as myositis, polyradiculoneuropathy, or cranial neuropathy, and, less frequently, involve the central nervous system, causing encephalitis, meningitis, or myelitis. Although somehow reminiscent of the disorders that neurologists are familiar to deal with in their daily practice, n-irAEs are characterized by distinctive features from their idiopathic counterparts; for instance, myositis may have a predominant oculo-bulbar involvement reminiscent of myasthenia gravis and frequently associates with myocarditis; peripheral neuropathy, although often resembling Guillain-Barré syndrome, usually responds to corticosteroids. Remarkably, several associations between the neurological phenotype and the type of ICIs or the type of cancer have emerged in the last few years, and the growing administration of ICIs in patients with neuroendocrine cancers has led to an increased number of reports of paraneoplastic neurological syndromes (triggered or worsened by ICIs). This review aims to update current knowledge regarding the clinical presentation of n-irAEs. We also discuss the essential parts of the diagnostic approach, and we provide general recommendations for the management of these disorders.

Do peripheral neuropathies differ among immune checkpoint inhibitors? Reports from the European post-marketing surveillance database in the past 10 years

Although the immunotherapy advent has revolutionized cancer treatment, it, unfortunately, does not spare cancer patients from possible immune-related adverse events (irAEs), which can also involve the peripheral nervous system. Immune checkpoint inhibitors (ICIs), blocking cytotoxic T-lymphocyteassociated protein 4 (CTLA-4), programmed cell death protein 1 (PD-1), or programmed cell death ligand 1 (PD-L1), can induce an immune imbalance and cause different peripheral neuropathies (PNs). Considering the wide range of PNs and their high impact on the safety and quality of life for cancer patients and the availability of large post-marketing surveillance databases, we chose to analyze the characteristics of ICI-related PNs reported as suspected drug reactions from 2010 to 2020 in the European real-world context. We analyzed data collected in the European pharmacovigilance database, Eudravigilance, and conducted a systematic and disproportionality analysis. In our study, we found 735 reports describing 766 PNs occurred in patients treated with ICIs. These PNs included Guillain-Barré syndrome, Miller-Fisher syndrome, neuritis, and chronic inflammatory demyelinating polyradiculoneuropathy. These ADRs were often serious, resulting in patient disability or hospitalization. Moreover, our disproportionality analysis revealed an increased reporting frequency of PNs with tezolizumab compared to other ICIs. Guillain-Barré syndrome is a notable potential PN related to ICIs, as it is associated with a significant impact on patient safety and has had unfavorable outcomes, including a fatal one. Continued monitoring of the safety profile of ICIs in real-life settings is necessary, especially considering the increased frequency of PNs associated with atezolizumab compared with other ICIs.

Encephalopathy after COVID-19 vaccination during treatment with nivolumab: A case report

Vaccination is useful for the prevention of COVID-19 and is recommended for everyone, especially people with a weakened immune system. However, various neurological complications have been reported following vaccination. Here, we report the case of a 25 years-old, Japanese man, who presented with acute encephalopathy two days after the second dose of the COVID-19 vaccine. He had been treated with nivolumab, a medication used to treat cancer. He had a high fever and was confused upon admission, and the antibody test was positive for anti-myelin oligodendrocyte glycoproteins. Abnormal signal intensity at the splenium corporis callosi was observed on diffusion-weighted imaging of the brain. We diagnosed him with autoimmune encephalitis and initiated intravenous methylprednisolone, after which, the patient's symptoms rapidly subsided.

Evaluation and management of acute high-grade immunotherapy-related neurotoxicity

Immune checkpoint inhibitor monoclonal antibodies allow the host's immune system to attack tumors, which has revolutionized cancer care over the last decade. As the use of immune checkpoint inhibitors has expanded, so have autoimmune-like complications known as immune-related adverse events. These include the infrequent but increasingly more common, potentially deadly neurological immune related adverse events. When feeling acutely ill, patients will often seek care not from their oncologist but from their family physician, clinics, emergency, and urgent care sites, or other available providers. Thus, while assessing acutely ill cancer patients who are experiencing neurological symptoms, non-oncologists should be prepared to recognize, diagnose, and treat neurological immune related adverse events in addition to more familiar conditions. This narrative review is designed to update acute care clinicians on current knowledge and to present a symptom-based framework for evaluating and treating neurological immune related adverse events based on the leading immunotoxicity organizations' latest recommendations.

Cerebellar involvement associated with immune checkpoint inhibitors: A systematic review

BACKGROUND AND PURPOSE

Immune checkpoint inhibitors (ICIs) targeting programmed death receptor 1 (PD-1), cytotoxic T-lymphocyte-associated-4 (CTLA-4) and programmed cell death ligand 1 can be associated with immune-related adverse events (iRAEs). Amongst neurological iRAEs, cerebellar involvement seems to be rare and currently lacks a proper characterization. The aim of this study was to phenotype cerebellar iRAEs.

METHODS

A systematic review was performed according to PRISMA guidelines including reported patients with cerebellar involvement related to ICIs and with available individual data.

RESULTS

After screening 2765 records, 32 studies with 46 patients were included. Median age was 63 years (20-82), and most patients were male (63.0%). Isolated cerebellitis was observed in 32.6% of cases, whilst the remaining cases had "cerebellitis plus", mostly associated with encephalitis/encephalopathy. Associated tumors included most frequently lung cancer, melanoma and Merkel cell carcinoma. PD-1 inhibitor was the most administered treatment (n = 29, 64.4%), whilst exposure to CTLA-4 inhibitor was rare (n = 2, 4.5%). Magnetic resonance imaging was abnormal in 43.2% of patients and inflammatory cerebrospinal fluid findings were frequently observed. Autoantibodies were detected in 61.9% of patients and included novel reactivities. Amongst treatment strategies, the most common were steroids (n = 36) and ICI discontinuation (n = 28, 90.3%). Relapses were reported in 10% of patients. Most patients showed improvement/remission (n = 31) but, at last follow-up, 12 had died. Isolated cerebellitis versus cerebellitis-plus differed in terms of outcomes, whilst seropositive versus seronegative patients had distinct tumor associations.

DISCUSSION

Cerebellar iRAEs are usually multifocal, have heterogeneous tumor associations, are most associated with PD-1 inhibitor exposure and are related to autoantibodies, including novel reactivities.

Imaging assessment of toxicity related to immune checkpoint inhibitors

In recent years, a wide range of cancer immunotherapies have been developed and have become increasingly important in cancer treatment across multiple oncologic diseases. In particular, immune checkpoint inhibitors (ICIs) offer promising options to improve patient outcomes. However, a major limitation of these treatments consists in the development of immune-related adverse events (irAEs) occurring in potentially any organ system and affecting up to 76% of the patients. The most frequent toxicities involve the skin, gastrointestinal tract, and endocrine system. Although mostly manageable, potentially life-threatening events, particularly due to neuro-, cardiac, and pulmonary toxicity, occur in up to 30% and 55% of the patients treated with ICI-monotherapy or -combination therapy, respectively. Imaging, in particular computed tomography (CT), magnetic resonance imaging (MRI), and 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT), plays an important role in the detection and characterization of these irAEs. In some patients, irAEs can even be detected on imaging before the onset of clinical symptoms. In this context, it is particularly important to distinguish irAEs from true disease progression and specific immunotherapy related response patterns, such as pseudoprogression. In addition, there are irAEs which might be easily confused with other pathologies such as infection or metastasis. However, many imaging findings, such as in immune-related pneumonitis, are nonspecific. Thus, accurate diagnosis may be delayed underling the importance for adequate imaging features characterization in the appropriate clinical setting in order to provide timely and efficient patient management. ¹⁸F-FDG-PET/CT and radiomics have demonstrated to reliably detect these toxicities and potentially have predictive value for identifying patients at risk of developing irAEs. The purpose of this article is to provide a review of the main immunotherapy-related toxicities and discuss their characteristics on imaging.

A case report of neuromyelitis optica spectrum disorder induced by pembrolizumab treatment for lung adenocarcinoma: a clinical and immunohistochemical study

BACKGROUND

We report a case of neuromyelitis optica spectrum disorders (NMOSD), who developed after the pembrolizumab treatment, an immune checkpoint inhibitor, against lung adenocarcinoma. The present case is discussed with the lung adenocarcinoma specimen which was stained by aquaporin-4 (AQP4) and with literature review of NMOSD linked to immune checkpoint inhibitors.

CASE PRESENTATION

A 62-year-old Japanese man presented with acute diencephalic syndrome, left optic neuritis, and myelitis 5 months after initiation of pembrolizumab treatment for lung adenocarcinoma. He was diagnosed with NMOSD based on serum anti-aquaporin-4 (AQP4) antibody positivity. Immunohistochemistry of lung biopsy samples showed AQP4 expression on CD68+ cells. This is the fifth reported case of AQP4+ NMOSD triggered by an immune checkpoint inhibitor and the first with a brain lesion. Four out of five NMOSD cases, including the present case and one case with lung metastasis, had lung cancer.

CONCLUSIONS

Immune checkpoint inhibitors may trigger AQP4+ NMOSD owing to their molecular similarity to AQP4 expressed in lung and glial tissues. Prompt brain/spinal cord imaging and anti-AQP4 antibody testing may facilitate early diagnosis of immune-mediated adverse event in central nervous system associated with immune checkpoint inhibitors.

Neurological adverse events of immune checkpoint blockade: from pathophysiology to treatment

PURPOSE OF REVIEW

We review the recent advances in neurological toxicities of immune checkpoint inhibitors, with a focus on underlying pathophysiologic mechanisms and the implications on their therapeutical management.

RECENT FINDINGS

A growing number of cancer patients benefit from immune checkpoint agents and oncologists are increasingly confronted with these novel autoimmune syndromes. During the last years, further progresses have occurred in this field, notably in the identification of specific clinical patterns, such as the association of myasthenic syndrome with myositis and myocarditis, and polyradiculoneuropathies accompanied by cerebrospinal fluid lymphocytic pleocytosis. In addition, recent immune-histological studies improved the understanding of the pathophysiologic mechanisms behind immune-related neurotoxicities.

SUMMARY

Neurological toxicity is rare compared with other organs and systems, but its potential morbidity and mortality requires a prompt management. If there is a consensus for steroids as a first-line treatment, no exhaustive clinical data exist for other treatments. Recent advances in the knowledge of pathophysiological mechanisms (behind these toxicities) should be taken into account for the management of these patients. Drugs targeting T-cell mediated inflammation should be preferred in patients who are refractory to steroids, whereas therapies targeting humoral mechanisms should be considered in specific cases associated with autoantibodies such as immune-related myasthenic syndrome.

Drug-related immune-mediated myelopathies

Iatrogenic immune-mediated inflammatory disorders of the spinal cord are an uncommon but potentially severe complication of drug therapy for several human diseases. Particularly the introduction of novel biological agents in the treatment of systemic inflammatory disorders and cancer immunotherapy have led to a significant increase in immune-related adverse events of the central nervous system (CNS). The use of Tumor necrosis factor alpha (TNF-alpha) inhibitors in rheumatic and inflammatory bowel diseases has been associated with demyelinating and other inflammatory CNS conditions, including myelitis. The introduction of immune checkpoint inhibitors in the treatment of several human malignancies has led to an increase in drug-induced immune-related adverse events including in the CNS. Other drugs that have been associated with immune-mediated myelitis include tyrosine-kinase inhibitors and chimeric antigen receptor (CAR) T Cell therapy. A high degree of suspicion is necessary when diagnosing these conditions, as early diagnosis and treatment is crucial in preventing further neurological damage and disability. The treatment of drug-induced inflammatory myelitis typically involves administration of high-dose intravenous corticosteroids, however additional immunosuppressive agents may be required in severe or refractory cases. While most cases are monophasic and remit following discontinuation of the offending agent, chronic immunosuppressive therapy may be indicated in cases with a progressive or relapsing disease course or when a diagnosis of a specific underlying neuro-inflammatory disorder is made. Outcomes are generally favorable, however depend on the specific therapeutic agent used, the clinical presentation and patient factors. In this review we aim to describe the clinical characteristics, imaging findings and management for the most common forms of iatrogenic immune-mediated myelopathies.

Thinking outside the box: non-canonical targets in multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system that causes demyelination, axonal degeneration and astrogliosis, resulting in progressive neurological disability. Fuelled by an evolving understanding of MS immunopathogenesis, the range of available immunotherapies for clinical use has expanded over the past two decades. However, MS remains an incurable disease and even targeted immunotherapies often fail to control insidious disease progression, indicating the need for new and exceptional therapeutic options beyond the established immunological landscape. In this Review, we highlight such non-canonical targets in preclinical MS research with a focus on five highly promising areas: oligodendrocytes; the blood-brain barrier; metabolites and cellular metabolism; the coagulation system; and tolerance induction. Recent findings in these areas may guide the field towards novel targets for future therapeutic approaches in MS.

Glucagon-Like Peptide-1 Receptor Agonists as Potential Myelination-Inducible and Anti-Demyelinating Remedies

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) were developed as insulinotropic and anti-hyperglycemic agents for the treatment of type 2 diabetes, but their neurotrophic and neuroprotective activities have been receiving increasing attention. Myelin plays a key role in the functional maintenance of the central and peripheral nervous systems, and recent in vivo and in vitro studies have shed light on the beneficial effects of GLP-1RAs on the formation and protection of myelin. In this article, we describe the potential efficacy of GLP-1RAs for the induction of axonal regeneration and remyelination following nerve lesions and the prevention and alleviation of demyelinating disorders, particularly multiple sclerosis.

Clinical Reasoning: A 48-Year-Old Woman With 6 Months of Vivid Visual Hallucinations

Visual hallucinations are frequently encountered in clinical practice. It is critical for neurologists, particularly those in training, to develop a systematic approach for evaluating patients presenting with such unique and often perplexing symptoms. In this study, we present the case of a 48-year-old woman who developed vivid visual hallucinations after receiving nivolumab for melanoma. We discuss the broad differential diagnosis for visual hallucinations and how history and examination can guide one's evaluation.

Neurologic adverse events of cancer immunotherapy

Cancer immunotherapy encompasses a wide range of treatment modalities that harness the anti-tumor effects of the immune system and have revolutionized oncological treatment in recent years, with approval for its use in more and more cancers. However, it is not without side effects. Several neurological adverse events have been recognized associated with immune checkpoint inhibitors (ICI) and chimeric antigen receptor (CAR) T-cell therapy, the two main classes of cancer immunotherapy. With the increase in the prevalence of oncological diseases and this type of therapy, it is improbable that neurologists, oncologists, hematologists, and other healthcare professionals who deal with cancer patients will not encounter this type of neurologic complication in their practice in the following years. This article aims to review the epidemiology, clinical manifestations, diagnosis, and management of neurological complications associated with ICI and CAR T-cell therapy.

Longitudinal extensive transverse myelitis after chemoradiation therapy with durvalumab, a rare complication: case report

Background

Longitudinal extensive transverse myelitis is a rare and potentially life-threatening complication of chemoradiation. Certain chemotherapy agents have been proposed to increased neurotoxicity with chemoradiation therapy. One such agent is durvalumab, a human IgG1 monoclonal antibody that blocks programmed death ligand 1, allowing T-cells to recognize and kill tumor cells. Durvalumab and other immune checkpoint inhibitors may also cause transverse myelitis without concomitant treatment with radiation. Durvalumab is a standard therapy for non-small cell lung carcinoma. Here we present a case of a 68-year-old male who presented after chemoradiation and durvalumab therapy with transverse myelitis extending outside the irradiation site.

Case presentation

A 68-year-old male presented to the emergency department with pain and weakness in his feet and hesitancy of urination. Medical history is significant for non-small cell lung cancer treated with chemoradiotherapy and consolidation therapy with durvalumab for one year. His last radiation treatment was 15 months prior, and his last infusion of durvalumab was 3 months prior. Exam revealed severe weakness of bilateral legs with absent vibration sensation. MRI showed central longitudinal extensive transverse myelitis extending from C4-T11. CSF studies showed 8 WBC with 63% lymphocyte predominance and a protein of 48. Oligoclonal bands and angiotensin-converting enzyme were negative. Serum Neuromyelitis Optica antibody (AQP4-IgG) and Myelin oligodendrocyte glycoprotein antibody (MOG-IgG) were negative. Infectious workup came back negative. The patient was treated with steroids and plasma exchange with mild improvement. Etiology remained unknown, but longitudinal extensive transverse myelitis following durvalumab chemoradiotherapy was thought to be the likely cause. He was discharged on a high-dose prednisone taper with outpatient follow-up. His condition worsened near the end of the steroid taper. High-dose prednisone and cyclophosphamide infusions were started with mild improvement and stabilization of the patient’s condition. He transitioned to methotrexate after completion of six cyclophosphamide infusions. The patient expired due to complications from his cancer.

Conclusion

Longitudinal extensive transverse myelitis is a rare and potentially life-threatening complication of durvalumab therapy. As durvalumab has become a standard treatment for non-small cell lung cancer, it is important to be able to identify and treat side effects.

Neurologic Toxicity of Immune Checkpoint Inhibitors: A Review of Literature

Immune checkpoint inhibitors have entailed a change of paradigm in the management of multiple malignant diseases and are acquiring a key role in an increasing number of clinical sceneries. However, since their mechanism of action is not limited to the tumor microenvironment, their systemic activity may lead to a wide spectrum of immune-related side effects. Although neurological adverse events are much less frequent than gastrointestinal, hepatic, or lung toxicity, with an incidence of <5%, their potential severity and consequent interruptions to cancer treatment make them of particular importance. Despite them mainly implying peripheral neuropathies, immunotherapy has also been associated with an increased risk of encephalitis and paraneoplastic disorders affecting the central nervous system, often appearing in a clinical context where the appropriate diagnosis and early management of neuropsychiatric symptoms can be challenging. Although the pathogenesis of these complications is not fully understood yet, the blockade of tumoral inhibitory signals, and therefore the elicitation of cytotoxic T-cell-mediated response, seems to play a decisive role. The aim of this review was to summarize the current knowledge about the pathogenic mechanisms, clinical manifestations, and therapeutic recommendations regarding the main forms of neurotoxicity related to checkpoint inhibitors.

Neurologic Complications of Immune Checkpoint Inhibitors

The clinical use of cancer immunotherapy with immune checkpoint inhibitors has transformed the management of cancer and added another effective treatment option for different types of malignancies. The blockade of immune checkpoint pathways triggers an enhanced immune response leading to cancer regression but may also lead to autoimmune toxicities or immune-related adverse events, which may involve skin, endocrine, respiratory, gastrointestinal or neurologic manifestations. Clinically relevant neurologic complications involving the central and/or peripheral nervous system affect up to 1% of patients treated with immune checkpoint inhibitors and may be associated with significant morbidity and mortality. Common neurologic complications include aseptic meningitis and encephalitis, hypophysitis, myasthenia, myositis and neuropathies. Neurologic immune-related adverse events after immune checkpoint inhibition should be distinguished from cancer progression or other complications of cancer therapy (e.g. infections). The treatment of neurologic complications may include holding or withdrawing cancer immunotherapy, anti-inflammatory and immunosuppressive therapies with corticosteroids and steroid-sparing agents, immunomodulation with intravenous immune globulin or plasmapheresis and symptomatic treatment (e.g. antiepileptic medications, pain medications).

A review of neurotoxicities associated with immunotherapy and a framework for evaluation

Immuno-oncology agents, including immune checkpoint inhibitors (ICIs) and chimeric antigen receptor T (CAR-T) cell therapies, are increasing in use for a growing list of oncologic indications. While harnessing the immune system against cancer cells has a potent anti-tumor effect, it can also cause widespread autoimmune toxicities that limit therapeutic potential. Neurologic toxicities have unique presentations and can progress rapidly, necessitating prompt recognition. In this article, we review the spectrum of central and peripheral neurologic immune-related adverse events (irAEs) associated with ICI therapies, emphasizing a diagnostic framework that includes consideration of the therapy regimen, timing of symptom onset, presence of non-neurologic irAEs, pre-existing neurologic disease, and syndrome specific features. In addition, we review the immune effector cell-associated neurotoxicity syndrome (ICANS) associated with CAR-T cell therapy and address diagnostic challenges specific to patients with brain metastases. As immunotherapy use grows, so too will the number of patients affected by neurotoxicity. There is an urgent need to understand pathogenic mechanisms, predictors, and optimal treatments of these toxicities, so that we can manage them without sacrificing anti-tumor efficacy.

A brief report on incidence, radiographic feature and prognostic significance of brain MRI changes after anti-PD-1/PD-L1 therapy in advanced non-small cell lung cancer

INTRODUCTION

Neurologic immune-related adverse events (nirAEs) are uncommon but potentially lethal complications of immune checkpoint inhibitor (ICI) treatment. However, the incidence, radiographic features and prognostic significance of brain magnetic resonance imaging (MRI) changes after ICI treatment remain largely unknown.

METHODS

Consecutive patients with advanced non-small cell lung cancer (NSCLC) at three participating institutions receiving anti-PD-1/PD-L1 therapy from June 2017 to September 2020 were screened, and those who received brain MRI within 6 weeks before ICI initiation and at least one follow-up brain MRI after ICI treatment were included. Serial brain MRI images were independently reviewed by two experienced radiologists.

RESULTS

With a median follow-up of 13.2 months, 27 (20.0%) of the 135 enrolled patients developed certain kind of brain MRI aberration. The 1-, 2- and 3-year cumulative incidence of brain MRI aberration was 17.1%, 36.3% and 52.2%, respectively. Brain MRI aberration indicative of stroke, mimicking typical white matter lesions and presenting as T2-hyperintensity suggestive of CNS vasculitis or encephalitis, was documented in 11, 9 and 4 patients, respectively. Patients with brain MRI aberration had higher clinical benefit rate (p = 0.030), longer progression-free survival (p = 0.015) and a tendency of improved overall survival (p = 0.054).

CONCLUSIONS

Brain MRI aberrations developed after ICI treatment are not uncommon, and their manifestations vary a lot. Patients developing brain MRI aberrations tended to have better prognosis, which needed to be further investigated.

Drug-related demyelinating syndromes: understanding risk factors, pathophysiological mechanisms and magnetic resonance imaging findings

Some drugs and medications can precipitate immune system deregulations, which might be confused with recurrent demyelinating diseases, such as multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMO), exacerbations of an existing disease, neoplastic lesions or other conditions. In this narrative review we describe some of the most relevant drugs and medications associated with iatrogenic demyelination. The anthelminthic agent levamisole is a frequent cocaine adulterant and can precipitate an exacerbated immune response attacking the central nervous system (CNS). High-efficacy multiple sclerosis (MS) drugs might induce a selective CNS immunosuppression, making it susceptible for opportunistic infections that course with demyelination, such as progressive multifocal leukoencephalopathy. Sometimes, the interruption of a high-efficacy drug to treat MS can induce a rapid CNS reentry of lymphocytes, exacerbating demyelinating processes and triggering rebound syndromes. Furthermore, selective cytokines inhibition, such as anti-TNFα agents, might induce an imbalance between cell death and proliferation inducing a paradoxical increase of CNS tumor necrosis factor (TNF), affecting the activity of lymphocytes, microglia and macrophages, triggering aberrant inflammation and demyelination. Immune checkpoint inhibitors are a new class of antineoplastic drugs that enhance the immune response against tumor cells by an upregulation of T-cell activity. However, this hyperactivation of the immune system might be associated with induction of unwanted autoimmune responses. In this paper we review the risk factors, the possible pathological mechanisms and the magnetic resonance imaging (MRI) findings of these drug-related demyelinating syndromes.

Can rheumatologists stop causing demyelinating disease?

BACKGROUND

Perhaps the most informative experiments in human disease are clinical trials and notably, responses to specific therapies can be highly-informative to help understand disease pathogenesis. There are reagents that inhibit a variety of different autoimmune conditions, such as CD20 memory B cell depleters that are active in both multiple sclerosis (MS), rheumatoid arthritis (RA) and other conditions, suggesting influences on common immune mechanisms in different diseases. However, a notable exception seemed to be the use of tumour necrosis factor (TNF) inhibitors that limits RA, yet seem to, rarely, trigger demyelination and induce MS. This was first seen with TNF-inhibiting monoclonal antibodies and TNF-receptor-immunoglobulin fusion proteins. However, this is also seen with tyrosine and Janus kinase inhibitors that inhibit RA, yet induce demyelinating disease in some individuals PURPOSE: To provide an overview, from a B cell centric perspective, that may underpin the biology that links arthritis treatments to the development of demyelinating disease.

CONCLUSIONS

It is apparent that the disease modifying anti-rheumatoid drugs that cause demyelination share a number of common features. These agents tend to inhibit TNF-receptor signalling, augment or exhibit limited inhibitor activity on class-switched memory B cells and importantly appear to be relatively excluded from the central nervous system (CNS). They will thus not target ectopic B cell follicles in the CNS, unlike that occurring in peripheral autoimmunity as seen with anti-TNF treatments in RA. Agents such as ibudilast and some Janus kinase inhibitors that inhibit TNF and clearly penetrate the CNS do not appear to induce demyelination and may even be neuroprotective. It remains to be established whether selection or development of CNS penetrant agents may avoid CNS-complications of treatments for RA. Clearly, further studies are warranted.