Seronegative antibody-mediated neurology after immune checkpoint inhibitors

Immune checkpoint inhibitors-associated cranial nerves involvement: a systematic literature review on 136 patients

OBJECTIVE

Describe the demographic data and clinical phenotype of cranial palsy induced by immune checkpoint inhibitors (CNP-ICI).

METHODS

A systematic literature review of the literature was performed in Pubmed, Web of Science, and Embase, including 68 articles and 136 patients (PROSPERO no. CRD42024517262).

RESULTS

Out of the 1205 articles screened, 68 articles were included after fulfilling the inclusion criteria, for a total of 136 patients. All articles were case reports and case series. In the cohort studied, 52% of patients were treated with anti PD-1/PDL-1 therapies, 14% with anti CTLA-4 therapies, and 34% with a combination of anti CTLA-4 and anti PD-1/PDL-1 therapies. The facial nerve was the most affected cranial nerve, involved in 38% of cases, followed by the optic nerve (35%), the cochleovestibular nerve (12%), and the abducens nerve (10%). The median time from the initial immune checkpoint inhibitor (ICI) injection to the onset CNP-ICI was 10 weeks (IQR 4-20). Magnetic resonance imaging demonstrated contrast enhancement or abnormal signal of the affected nerve in 43% of cases. Cerebrospinal fluid analysis indicated lymphocytic pleocytosis in 59% of cases. At the onset of immune-related adverse events, 89% of patients discontinued immunotherapy, and 92% received treatment for CNP-ICI. Treatment regimens included corticosteroids in 86% of cases, intravenous immunoglobulin in 21%, and plasma exchange in 5.1%. Among the whole population, 33% achieved recovery, 52% showed clinical improvement, 16% remained stable, and 3% experienced worsening of their condition. Rechallenge with immunotherapy was significantly associated with the emergence of new immune-related Adverse Events (irAEs).

CONCLUSION

ICI therapy may lead to cranial nerve involvement, particularly affecting the facial nerve, typically presenting around 10 weeks after treatment initiation. While corticosteroid therapy often resulted in patient improvement, rechallenging with ICIs were associated with new irAEs.

Beyond T cell toxicity - Intrathecal chemokine CXCL13 indicating B cell involvement in immune-related adverse events following checkpoint inhibition: A two-case series and literature review

BACKGROUND AND PURPOSE

This study was undertaken to raise awareness of a role of B cells in immune checkpoint inhibitor (ICI)-associated neurological immune-related adverse events (nirAE).

METHODS

A systematic literature review was made, with case observations of a melanoma and a non-small cell lung cancer (NSCLC) patient who developed ICI-associated nirAE with cerebrospinal fluid (CSF) findings indicating B cell involvement.

RESULTS

Two patients receiving ipilimumab/nivolumab for melanoma and chemotherapy/pembrolizumab for NSCLC developed nirAE in the form of myocarditis/myositis/myasthenia gravis overlap syndrome (triple M) and cerebellitis plus longitudinal transverse myelitis (c-LETM), respectively. Intrathecal inflammation with chemokine C-X-C motif ligand (CXCL13) elevation was present in both patients; the triple M case had acetylcholine receptor antibodies, antititin reactivity, altered CD4/CD8 T cell ratio in blood, and depressed programmed death-1 (PD-1) expression on CSF T cells; the c-LETM case showed intrathecal antibody production and plasma cells. Both patients insufficiently responded to first-line treatment. The NSCLC case improved upon administration of B cell-depleting therapy with rituximab, whereas the melanoma patient died before escalation therapy was initiated. Literature research revealed one additional ICI-associated LETM case with intrathecal CXCL13 elevation, three cases with ICI-associated aquaporin-4 antibody neuromyelitis spectrum disorder, and evidence of B cell-mediated toxicity based on antibody-mediated immune pathologies in ICI-associated immune-related adverse events.

CONCLUSIONS

The case observations highlight the plethora of uncertainties in diagnosis and treatment of ICI-associated nirAE, exemplify the heterogeneity of immune mechanisms involved, and suggest a role of B cells, which may be underdiagnosed. Intrathecal CXCL13 may serve as a biomarker of B cell involvement in nirAE, supported by intrathecal immunoglobulin synthesis, presence of plasma cells, and/or recruitment of cognate immune cells.

Neurological adverse events of immune checkpoint inhibitors and the development of paraneoplastic neurological syndromes

Immune checkpoint inhibitors, a class of oncological treatments that enhance antitumour immunity, can trigger neurological adverse events closely resembling paraneoplastic neurological syndromes. Unlike other neurological adverse events caused by these drugs, post-immune checkpoint inhibitor paraneoplastic neurological syndromes predominantly affect the CNS and are associated with neural antibodies and cancer types commonly found also in spontaneous paraneoplastic neurological syndromes. Furthermore, post-immune checkpoint inhibitor paraneoplastic neurological syndromes have poorer neurological outcomes than other neurological adverse events of immune checkpoint inhibitors. Early diagnosis and initiation of immunosuppressive therapy are likely to be crucial in preventing the accumulation of neurological disability. Importantly, the neural antibodies found in patients with post-immune checkpoint inhibitor paraneoplastic neurological syndromes are sometimes detected before treatment, indicating that these antibodies might help to predict the development of neurological adverse events. Experimental and clinical evidence suggests that post-immune checkpoint inhibitor paraneoplastic neurological syndromes probably share immunological features with spontaneous paraneoplastic syndromes. Hence, the study of post-immune checkpoint inhibitor paraneoplastic neurological syndromes can help in deciphering the immunopathogenesis of paraneoplastic neurological syndromes and in identifying novel therapeutic targets.

Autoimmune and paraneoplastic seizures

Seizures are a common feature of autoimmune encephalitis and are especially prevalent in patients with the commonest autoantibodies, against LGI1, CASPR2 and the NMDA, GABAB, and GABAA receptors. In this chapter, we discuss the classification, clinical, investigation, and treatment aspects of patients with these, and other autoantibody-mediated and -associated, illnesses. We highlight distinctive and common seizure semiologies which, often alongside other features we outline, can help the clinical diagnosis of an autoantibody-associated syndrome. Next, we classify these syndromes by either focusing on whether they represent underlying causative autoantibodies or T-cell-mediated syndromes and on the distinction between acute symptomatic seizures and a more enduring tendency to autoimmune-associated epilepsy, a practical and valuable distinction for both patients and clinicians which relates to the pathogenesis. We emphasize the more effective immunotherapy response in patients with causative autoantibodies, and discuss the emerging evidence for various first-, second-, and third-line immunotherapies. Finally, we highlight available clinical rating scales which can guide autoantibody testing and immunotherapy in patients with seizures of unknown etiology. Throughout, we relate the clinical and therapeutic observations to the immunobiology and neuroscience which drive these seizures.

A case report of longitudinal extensive transverse myelitis: immunotherapy related adverse effect vs. COVID-19 related immunization complications

Background: Transverse myelitis (TM) is a rare, acquired neuro-immunological spinal cord disorder that occurs with rapid onset of motor weakness, sensory deficits with bowel and bladder dysfunction. Patients being treated with immune checkpoint inhibitors (ICIs) for advanced malignancy have a known higher propensity of developing neuro immune complications. With the advent of COVID-19 pandemic there have been reported cases of TM with COVID-19 immunization. The reported infrequency of TM with both of the aforementioned causes makes delineation of the etiology challenging.Methods: We present a patient with metastatic small cell lung cancer (SCLC) on maintenance Atezolizumab immunotherapy who developed longitudinal extensive transverse myelitis (LETM) after administration of second dose of COVID-19 mRNA vaccine one day prior to presenting symptoms of acute paralysis of the lower extremity, sensory loss from chest down with overflow incontinence. A clinical diagnosis of myelopathy was supported by MRI of the spine illustrating enhancing lesions from C7-T7 concerning for LETM.Results: A 5-day course of pulsed methylprednisolone followed by therapeutic plasma exchange for 3 days resulted in only minimal improvement in the neurologic exam with increased strength in his lower extremities while the sensory level remained unchanged.Conclusions: This case demonstrates the complication and symptomatology of TM in the setting of anti-PD-L1 monoclonal antibody with coincidental COVID-19 mRNA vaccine administration. The causal relationship between the vaccine and LETM is difficult to establish. However, the presence of a known inciting factor hints at a possible exaggeration of the existing neuro-inflammatory process.

Role of B cells in immune-related adverse events following checkpoint blockade

Blockade of immune checkpoints has transformed the therapy of several cancers. However, immune-related adverse events (irAEs) have emerged as a major challenge limiting the clinical application of this approach. B cells are recognized as major players in the pathogenesis of human autoimmunity and have been successfully targeted to treat these disorders. While T cells have been extensively studied as therapeutic targets of immune checkpoint blockade (ICB), these checkpoints also impact B cell tolerance. Blockade of immune checkpoints in the clinic is associated with distinct changes in the B cell compartment that correlate with the development of irAEs. In this review, we focus on the possible role of humoral immunity, specifically human B cell subsets and autoantibodies in the pathogenesis of ICB-induced irAEs. There remains an unmet need to better understand the T:B cell cross talk underlying the activation of pathogenic B cells and the development of ICB-induced irAEs. Such studies may identify new targets or approaches to prevent or treat irAEs and improve the application of ICB therapy in cancer.

Neurological adverse events associated with PD-1/PD-L1 immune checkpoint inhibitors

Immunotherapy is a promising method for cancer treatment. Among them, immune checkpoint inhibitors targeting PD-1/PD-L1 are increasingly used for certain cancers. However, with the widespread use of such drugs, reports of immune-related adverse events (irAEs) are also increasing. Neurological adverse events (nAEs) are one of the irAEs that affect the peripheral and central nervous systems. They are characterized by low incidence, hard to diagnose, and life-threatening risks, which have a significant impact on the prognosis of patients. Biomarker-based early diagnosis and subsequent treatment strategies are worthy of attention, and comprehensive management of irAEs is important for optimizing patients' quality of life and long-term outcomes. In this review, we summarized the mechanisms, common symptoms, early biomarkers, treatments, and future research directions of nAEs, in order to provide a comprehensive overview of immune checkpoint inhibitor-related nAEs targeting PD-1/PD-L1.

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.

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.

Paraneoplastic Neurologic Disorders

PURPOSE OF REVIEW

To provide an overview and highlight recent updates in the field of paraneoplastic neurologic disorders.

RECENT FINDINGS

The prevalence of paraneoplastic neurologic disorders is greater than previously reported and the incidence has been rising over time, due to improved recognition in the era of antibody biomarkers. Updated diagnostic criteria that are broadly inclusive and also contain diagnostic risk for clinical presentations (high and intermediate) and diagnostic antibodies (high, intermediate, and low) have replaced the original 2004 criteria. Antibody biomarkers continue to be characterized (e.g., KLHL-11 associated with seminoma in men with brainstem encephalitis). Some paraneoplastic antibodies also provide insight into likely immunotherapy response and prognosis. The rise of immune checkpoint inhibitors as cancer therapeutics has been associated with newly observed immune-mediated adverse effects including paraneoplastic neurological disorders. The therapeutic approach to paraneoplastic neurologic disorders is centered around cancer care and trials of immune therapy. The field of paraneoplastic neurologic disorders continues to be advanced by the identification of novel antibody biomarkers which have diagnostic utility, and give insight into likely treatment responses and outcomes.

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.

Characteristics of immune checkpoint inhibitor-induced encephalitis and comparison with HSV-1 and anti-LGI1 encephalitis: A retrospective multicentre cohort study

AIM

Immune checkpoint inhibitor-induced encephalitis (ICI-iE) is a rare but life-threatening toxicity of immune checkpoint inhibitor treatment. We aim to identify the characteristics of ICI-iE and describe factors that discriminate it from herpes simplex virus (HSV)-1 encephalitis and anti-leucine-rich glioma-inactivated 1 (anti-LGI1) encephalitis, as two alternative entities of encephalitis.

METHODS

In this retrospective multicentre cohort study, we collected patients with ICI-iE reported to the Side Effect Registry Immuno-Oncology from January 2015 to September 2021 and compared their clinical features and outcome with 46 consecutive patients with HSV-1 or anti-LGI1 encephalitis who were treated at a German neurological referral centre.

RESULTS

Thirty cases of ICI-iE, 25 cases of HSV-1 encephalitis and 21 cases of anti-LGI1 encephalitis were included. Clinical presentation of ICI-iE was highly variable and resembled that of HSV-1 encephalitis, while impairment of consciousness (66% vs. 5%, p = .007), confusion (83% vs. 43%; p = .02), disorientation (83% vs. 29%; p = .007) and aphasia (43% vs. 0%; p = .007) were more common in ICI-iE than in anti-LGI1 encephalitis. Antineuronal antibodies (17/18, 94%) and MRI (18/30, 60%) were mostly negative in ICI-iE, but cerebrospinal fluid (CSF) showed pleocytosis and/or elevated protein levels in almost all patients (28/29, 97%). Three patients (10%) died of ICI-iE. Early immunosuppressive treatment was associated with better outcome (r = 0.43).

CONCLUSIONS

ICI-iE is a heterogeneous entity without specific clinical features. CSF analysis has the highest diagnostic value, as it reveals inflammatory changes in most patients and enables the exclusion of infection. Early treatment of ICI-iE is essential to prevent sequelae and death.

Plasma Exchange for Severe Immune-Related Adverse Events from Checkpoint Inhibitors: An Early Window of Opportunity?

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of several advanced malignancies leading to durable remission in a subset of patients. Their rapidly expanding use has led to an increased frequency of immune-related adverse events (irAEs). The pathogenesis of irAEs is poorly understood but may involve aberrant activation of T cells leading to inflammatory cytokine release or production of pathogenic antibodies leading to organ damage. Severe irAEs can be extremely debilitating and, in some cases, life threatening. IrAEs may not always be corticosteroid responsive or may require excessively high, often toxic, corticosteroid doses. Therapeutic plasma exchange (PLEX) is a treatment modality that has shown promising results for the management of certain severe irAEs, including irAEs that are not mentioned in current treatment guidelines. PLEX may attenuate ongoing irAEs and prevent delayed irAEs by accelerating clearance of the ICI, or by acutely removing pathogenic antibodies, cytokines, and chemokines. Here, we summarize examples from the literature in which PLEX was successfully used for the treatment of irAEs. We posit that timing may be a critical factor and that earlier utilization of PLEX for life-threatening irAEs may result in more favorable outcomes. In individuals at high risk for irAEs, the availability of PLEX as a potential therapeutic mitigation strategy may encourage life-saving ICI use or rechallenge. Future research will be critical to better define which indications are most amenable to PLEX, particularly to establish the optimal place in the sequence of irAE therapies and to assess the ramifications of ICI removal on cancer outcomes.

Association Between Clinical Factors and Result of Immune Checkpoint Inhibitor Related Myasthenia Gravis: A Single Center Experience and Systematic Review

Background

Neurological immune-related adverse events (nirAEs) are rare toxicities of immune-checkpoint inhibitors (ICI). With the increase use of ICIs, incidence of nirAEs is growing, among which ICI related MG (irMG) is causing high fatality rate. Given the limited evidence, data from a large cohort of patients with irMG is needed to aid in recognition and management of this fatal complication.

Objective

This study aimed to summarize clinical characteristics of irMG and explore predictors of irMG clinical outcome.

Methods

We summarized our institution's patients who were diagnosed as irMG between Sep 2019 and Oct 2021. We systematically reviewed the literature through Oct 2021 to identify all similar reported patients who met inclusion criteria. As the control group, patients with idiopathic MG were used. We collected data on clinical features, management, and outcomes of both irMG and idioMG cases. Further statistical analysis was conducted.

Results

Sixty three irMG patients and 380 idioMG patients were included in the final analysis. For irMG patients, six were from our institution while the rest 57 were from reported cases. The average age of irMG patients is 70.16 years old. Forty three were male. Average time from first ICI injection to symptom onset was 5.500 weeks. Eleven patients had a past history of MG. Higher MGFA classification and higher QMGS rates were observed in irMG patients compared to idioMG patients. For complication, more irMG patients had myositis or myocarditis overlapping compared to idioMG patients. The most commonly used treatment was corticosteroids for both idioMG and irMG. Twenty one patients (35%) with irMG had unfavorable disease outcome. Single variate and multivariate binary logistic regression proved that association with myocarditis, high MGFA classification or QMGS rates at first visit were negatively related to disease outcome in irMG patients.

Conclusion

irMG is a life-threatening adverse event. irMG has unique clinical manifestations and clinical outcome compared to idioMG. When suspicious, early evaluation of MGFA classification, QMGS rates and myositis/myocarditis evaluation are recommended.

Neurologic Toxicities of Immunotherapy

Immunotherapy has revolutionized treatment of cancer over the past two decades. The antitumor effects of immunotherapy approaches are at the expense of growing spectrum of immune-related adverse events (irAEs) due to cross-reactivity between the tumor and normal host tissue. These adverse events can happen in any organ and range from mild to severe and even life-threatening conditions. While neurological irAEs associated with immune checkpoint inhibitors (CPIs) are rare, they pose a significant challenge in management as the clinical phenotypes are heterogenous and frequently necessitate cessation of therapy and systemic immune suppression and lead to transient functional decline. On the other hand, immune effector cell-associated neurotoxicity (ICANS) is common, frequently occurs in conjunction with cytokine release syndrome (CRS), and poses a significant clinical challenge to the development and widespread use of these effective therapies. Early recognition of these neurological syndromes, timely diagnosis, and thoughtful management are key for further clinical development of these effective therapies in cancer patients. Here, we describe clinical phenotypes of CPI-induced neurological complications and ICANS and discuss steps in clinical monitoring, diagnosis, and effective management.

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).

Uncommon inflammatory/immune-related myelopathies

The differential diagnosis for immune-mediated myelopathies is broad. Although clinical manifestations overlap, certain presentations are suggestive of a particular myelopathy etiology. Spine MRI lesion characteristics including the length and location, and the pattern of gadolinium enhancement, help narrow the differential diagnosis and exclude an extrinsic compressive cause. The discovery of specific antibodies that serve as biomarkers of myelitis such as aquaporin-4-IgG and myelin-oligodendrocyte -glycoprotein-IgG (MOG-IgG), has improved our understanding of myelitis pathophysiology and facilitated diagnosis. In this review we will focus on the pathophysiology, clinical presentation, imaging findings and treatment and outcomes of uncommon immune-mediated myelopathies.

Immune Checkpoint Inhibitor-related Guillain-Barré Syndrome: A Case Series and Review of the Literature

Immune checkpoint inhibitors (ICIs) have been approved for the treatment of various malignancies with promising clinical outcomes. Treatment can, however, be accompanied by serious immune-related adverse events. Neurological adverse events like Guillain-Barré syndrome (GBS) are rare but potentially life-threatening. We present 3 cases of ICI-related GBS; review cases described in current literature, and discuss treatment strategies. Three patients developed GBS after ICI treatment. The first case with pembrolizumab had a fatal outcome despite treatment with multiple regimens, including steroids and intravenous immunoglobulin (IVIg). The other 2 cases with nivolumab-induced and pembrolizumab-induced GBS, respectively, responded well to treatment with IVIg and steroids. In the current literature, a total of 31 other cases were found. Treatment for ICI-related GBS mostly consisted of concurrent IVIg and steroids (44%), which led to clinical improvement in 73%. Most patients recovered with remaining symptoms (68%), while 10 patients developed respiratory failure (29%) and 6 patients (18%) died. ICI-related GBS should be suspected in patients on ICI treatment who develop subacute progressive weakness of the limbs, sensory loss, and areflexia. On the basis of the guidelines recommendations and our review of the literature, we advise first-line therapy with concurrent IVIg 0.4 g/kg/d for 5 days and prednisolone 1-2 mg/kg/d. Discontinuation of immunotherapy after ICI-related GBS is advised.

Guillain-Barré Syndrome-Like Polyneuropathy Associated with Immune Checkpoint Inhibitors: A Systematic Review of 33 Cases

Immune checkpoint inhibitors (ICIs) have been increasingly used in the treatment of various types of tumors with favorable results. But these treatments also led to a variety of immune-related adverse events (irAEs). Neurological irAEs such as Guillain-Barré Syndrome are rare and may have serious consequences once they occur. A systematic literature search was performed in PubMed and Embase for all case reports of GBS associated with ICIs published in English reporting on human beings from 1990 up to date. A total of 30 case reports (total patients = 33) were used for final analysis. The included cases were from 11 countries, covering 10 tumor types, with melanoma accounting for the largest number. The mean age was 62.2 ± 11.1 years old, and males were dominant (male: 26 and female: 7). The median time of initial symptoms was 8.2 weeks after the 1^st dose of ICIs. The most common manifestations of GBS associated with ICIs were weakness, hyporeflexia or areflexia, and paresthesia in order. The GBS subtypes suggested by electrophysiological results were acute inflammatory demyelinating polyneuropathy (AIDP), acute motor axonal neuropathy (AMAN), and Miller Fisher syndrome (MFS). The protein level of CSF in patients with GBS related to ICIs was 180.68 ± 152.51 mg/dl. Immediate termination of ICIs followed by intravenous immunoglobulin was the preferred treatment option. 72.7% of patients recovered or had residual mild dysfunction after treatment. Elderly male patients with melanoma were most likely to develop ICI-related GBS. The specific neurological symptoms, CSF analysis, and electrophysiological examination were important means of diagnosis.

Acute motor axonal neuropathy after ipilimumab and nivolumab treatment in melanoma brain metastases: A case report and review of the literature

The use of immune checkpoint inhibitors including ipilimumab and nivolumab has expanded for several tumors including melanoma brain metastasis. These have resulted in a growing spectrum of neurologic immune-related adverse events, including ones that are rare and difficult to diagnose and treat. Here, we present a patient with melanoma brain metastasis who was treated with immune checkpoint inhibitors and developed an Acute Motor Axonal Neuropathy. To our knowledge, this is the first case of Acute Motor Axonal Neuropathy as an immune-related adverse event associated with combination treatment of ipilimumab and nivolumab, who was successfully treated. A 28-year-old woman with metastatic BRAF V600E melanoma developed melanoma brain metastasis and was enrolled on Checkmate 204, a Phase 2 clinical trial using ipilimumab (3 mg/kg intravenous) and nivolumab (1 mg/kg intravenous) every 3 weeks for four cycles, followed by monotherapy with nivolumab (240 mg intravenous) every 2 weeks. A few days after Cycle 2 of ipilimumab and nivolumab, she developed a pure motor axonal neuropathy consistent with Acute Motor Axonal Neuropathy. She was treated with several immunosuppressive treatments including high dose methylprednisolone, immune globulin, and infliximab, and her motor neuropathy eventually improved several months after onset of symptoms. Unfortunately, she had progression of her systemic disease and died several months later. This is the first case reported of Acute Motor Axonal Neuropathy associated with ipilimumab and nivolumab, successfully treated with immune-suppressive therapy. As the field of immunotherapy expands with the increasing use of the immune checkpoint inhibitors, it is critical to increase our knowledge and understanding of the neurologic immune-related adverse events associated with immune checkpoint inhibitors. This includes the spectrum of rare neurologic immune-related adverse events, which can be quite difficult to recognize and treat. Early consultations with neurology may expedite a diagnosis and treatment plan in patients with unexplained weakness receiving immune checkpoint inhibitor therapy.

Case Report: THSD7A-Positive Membranous Nephropathy Caused by Tislelizumab in a Lung Cancer Patient

Immune checkpoint inhibitors (ICIs) became the standard treatment for many different kinds of cancers and can result in a variety of immune-related adverse events (irAEs). IrAEs of kidney are uncommon and consists of different pathology types. Among the different types, membranous nephropathy (MN) is rare and have not been well-described. Since MN can also be associated with malignancies, differential diagnosis in patients receiving ICIs who develop MN can be very difficult. We present the case of a 74-year-old man with metastatic non-small cell lung cancer who developed MN after ICIs therapy. The patient tested positive for thrombospondin type-1 domain-containing 7A antibodies (THSD7A) when diagnosed with MN. Supplementary examinations revealed the predisposing antigen in the primary tumor and present of the antibody after immunotherapy, which corresponded to the patient’s clinical course of nephropathy. Treatment consisting of systemic glucocorticoids and rituximab resulted in a good clinical response, and the THSD7A antibodies were no longer detected. In this case, we first discuss the potential mechanism of immunotherapy related MN, in which the activation of humoral immunity may play an important role.

Case Report: Longitudinal Extensive Transverse Myelitis With Novel Autoantibodies Following Two Rounds of Pembrolizumab

A 63-year-old male with metastatic non-small cell lung cancer developed longitudinal extensive transverse myelitis (LETM) following two cycles of Pembrolizumab, an immune checkpoint inhibitor (ICI) targeting the programmed cell death receptor 1 (PD-1). Magnetic resonance imaging (MRI) showed centromedullary contrast enhancement at several levels, cerebrospinal fluid (CSF) cytology showed lymphocytic pleocytosis, and indirect immunofluorescence assay (IFA) on the primate cerebellum, pancreas, and intestine revealed strong binding of neuronal autoantibodies to unknown antigens. CSF C–X–C motif ligand 13 (CXCL13) was elevated. The patient was treated with plasma exchange (PEX) and intravenous (i.v.) methylprednisolone (MP) 1 g/day for 5 days followed by oral (p.o.) MP 100 mg/day for 10 days with clinical and radiological response. However, after discontinuation of MP, LETM relapsed and the patient developed paralytic ileus presumably due to autoimmune enteropathy and suffered a fatal gastrointestinal sepsis. Findings of novel neuronal autoantibodies and highly elevated CXCL13 in CSF suggest that the severe neurological immune-related adverse event (nirAE) was B-cell mediated contrary to the commonly assumed ICI-induced T-cell toxicity. An individual evaluation of the underlying pathophysiology behind rare nirAEs is essential for choosing treatment regimens and securing optimal outcome.

Autoimmune Disorders of the Nervous System: Pathophysiology, Clinical Features, and Therapy

Remarkable discoveries over the last two decades have elucidated the autoimmune basis of several, previously poorly understood, neurological disorders. Autoimmune disorders of the nervous system may affect any part of the nervous system, including the brain and spinal cord (central nervous system, CNS) and also the peripheral nerves, neuromuscular junction and skeletal muscle (peripheral nervous system, PNS). This comprehensive overview of this rapidly evolving field presents the factors which may trigger breakdown of self-tolerance and development of autoimmune disease in some individuals. Then the pathophysiological basis and clinical features of autoimmune diseases of the nervous system are outlined, with an emphasis on the features which are important to recognize for accurate clinical diagnosis. Finally the latest therapies for autoimmune CNS and PNS disorders and their mechanisms of action and the most promising research avenues for targeted immunotherapy are discussed.

Paraneoplastic Neurological Syndromes and Beyond Emerging With the Introduction of Immune Checkpoint Inhibitor Cancer Immunotherapy

Paraneoplastic neurological syndromes are more commonly seen with malignancies such as small cell lung cancer, thymoma, gynecological malignancies, and breast cancer as well as seminoma. With the introduction of immune checkpoint inhibitor (ICI) cancer immunotherapy we see an increase of autoimmune neurological complications in patients with malignancies not traditionally associated with paraneoplastic neurological syndromes, such as melanoma and renal cell carcinoma. Immune checkpoint inhibitors enhance antitumor immune responses resulting often in immune-related adverse effects that can affect any organ, including the central and peripheral nervous system, neuromuscular junction and muscle. Neurological complications are rare; neuromuscular complications are more common than central nervous system ones but multifocal neurological presentations are often encountered. The vast majority of neurological complications appear within 3 months of ICI initiation, but have been described even after ICI cessation. Neural autoantibody testing reveals autoantibodies in approximately half of the patients with CNS complications. Early suspicion and diagnosis is critical to avoid worsening and improve outcomes. Therapeutic strategies depend on the severity of the symptoms and initially typically involve discontinuation of ICI and high dose steroids. Further immunosuppression might be necessary. Outcomes are dependent on patient's characteristics and clinical presentations.

Neurological complications of immune checkpoint inhibitor cancer immunotherapy

Neurological autoimmunity is increasingly recognized as a complication of immune checkpoint inhibitor (ICI) cancer immunotherapy. ICIs act by enhancing endogenous anti-tumor immune responses and can also lead to autoimmunity affecting all organs. ICI-related neurological autoimmunity is rare, most often manifests with neuromuscular involvement and more rarely affects the central nervous system. Neurological complications often often present in the first three months of ICI treatment but can also appear after ICI discontinuation. These can occur in patients with tumors not traditionally associated with paraneoplastic neurological autoimmunity, such as melanoma and renal-cell carcinoma and should be suspected when a new neurological symptoms present while on ICI and cannot be explained by disease progression or as a consequence of metabolic dysfunction. Treatment consists of ICI discontinuation or withdrawal depending on the severity with or without immunosuppression. Generally, improvement is observed depending on the patient's baseline characteristics and neurological presentation.

Calcium-sensing receptor autoantibody-mediated hypoparathyroidism associated with immune checkpoint inhibitor therapy: diagnosis and long-term follow-up

Background

Immune checkpoint inhibitors (ICIs) have produced significant survival benefit across many tumor types. However, immune-related adverse events are common including autoimmune responses against different endocrine organs. Here, a case of ICI-mediated hypoparathyroidism focusing on long-term follow-up and insights into its etiology is presented.

Case and methods

A 73-year-old man developed severe symptomatic hypocalcemia after the initiation of ipilimumab and nivolumab for the treatment of metastatic melanoma. Hypoparathyroidism was diagnosed with undetectable intact parathyroid hormone (PTH). Immunoprecipitation assays, ELISAs, and cell-based functional assays were used to test the patient for antibodies against the calcium-sensing receptor (CaSR). NACHT leucine-rich repeat protein 5 (NALP5) and cytokine antibodies were measured in radioligand binding assays and ELISAs, respectively.

Results

The patient’s symptoms improved with aggressive calcium and vitamin D supplementation. At 3 years and 3 months since the diagnosis of hypoparathyroidism, PTH was still inappropriately low at 7.6 pg/mL, and attempted discontinuation of calcium and calcitriol resulted in recurrent symptomatic hypocalcemia. Analysis for an autoimmune etiology of the patient’s hypoparathyroidism indicated that CaSR antibodies were negative before treatment and detected at multiple time points afterwards, and corresponded to the patient’s clinical course of hypoparathyroidism. CaSR antibodies purified from the patient’s serum activated the human CaSR. The patient was seronegative for NALP5 and cytokine antibodies, indicating that their hypoparathyroidism was not a manifestation of autoimmune polyendocrine syndrome type 1.

Conclusion

The etiology of hypocalcemia is likely autoimmune hypoparathyroidism caused by the development of CaSR-activating antibodies that might prevent PTH release from the parathyroid.

Neurologic Adverse Events of Immune Checkpoint Inhibitors: A Systematic Review

OBJECTIVE

To define the clinical characteristics, management, and outcome of neurologic immune-related adverse events (n-irAEs) of immune checkpoint inhibitors (ICIs).

METHODS

Systematic review of the literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

A total of 694 articles were identified. Two hundred fifty-six articles, with 428 individual patients, met the inclusion criteria. Reports regarding neuromuscular disorders (319/428, 75%) were more frequent than those on CNS disorders (109/428, 25%). The most common n-irAEs reports were myositis (136/428, 32%), Guillain-Barré syndrome and other peripheral neuropathies (94/428, 22%), myasthenic syndromes (58/428, 14%), encephalitis (56/428, 13%), cranial neuropathies (31/428, 7%), meningitis (13/428, 3%), CNS demyelinating diseases (8/428, 2%), and myelitis (7/428, 2%). Other CNS disorders were detected in 25/428 (6%) patients. Compared with the whole sample, myasthenic syndromes were significantly more Ab positive (33/56, 59%; p < 0.001). Anti-programmed cell death protein 1/programmed cell death ligand 1 was more frequent in myasthenic syndromes (50/58, 86%; p = 0.005) and less common in meningitis (2/13, 15%; p < 0.001) and cranial neuropathies (13/31, 42%; p = 0.005). Anti-cytotoxic T-lymphocyte antigen-4 ICIs were more frequent in meningitis (8/13, 62%; p < 0.001) and less common in encephalitis (2/56, 4%; p = 0.009) and myositis (12/136, 9%; p = 0.01). Combination of different ICIs was more frequent in cranial neuropathies (12/31, 39%; p = 0.005). Melanoma was more frequent in patients with peripheral neuropathies (64/94, 68%; p = 0.003) and less common in encephalitis (19/56, 34%; p = 0.001). The highest mortality rate was reached in myasthenic syndromes (28%).

CONCLUSION

Considering the increasing use of ICI therapy in the forthcoming future, this information can be valuable in assisting neurologists and oncologists in early n-irAEs diagnosis and treatment.

Neuro-ophthalmic Complications of Immune-Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) have revolutionized the field of oncology by modulating the immune cell-cancer cell interaction and thereby promoting immune system disinhibition in order to target several types of malignancies. There are three classes of immune checkpoint inhibitors (ICIs): anti-cytotoxic T-lymphocyte associated antigen 4 (CTLA-4), anti-programmed cell death protein-1 (PD-1), and anti-programmed cell death ligand-1 (PD-L1).It is not uncommon for physicians across all specialties to encounter a patient with a history of malignancy and ICI exposure, necessitating familiarity with their potential complications. In this review article, we discuss the most common immune-related adverse events (irAEs) pertaining to the central and peripheral nervous systems and their potential afferent and efferent neuro-ophthalmic manifestations. Early recognition and treatment of these irAEs, and discontinuation of the offending ICI are all critical steps to prevent morbidity and mortality.

Detect it so you can treat it: A case series and proposed checklist to detect neurotoxicity in checkpoint therapy

Background

Checkpoint inhibitors show impressive and durable responses in various cancer types and provide new avenues for cancer immunotherapy. However, these drugs have a variety of adverse events. Common autoimmune-related adverse effects include fatigue, hepatitis, skin rash, endocrine deficiencies, and colitis. Neurotoxicity has been reported, but its incidence and course remain unclear.

Methods

To illustrate the broad spectrum of neurotoxicity, we exemplarily report the neurological adverse events of five patients with melanoma and one patient with differentiated thyroid cancer who received checkpoint inhibitors at Essen University Hospital (Essen, Germany).

Results

After treatment with ipilimumab, nivolumab or pembrolizumab, neurotoxic effects included hypophysitis-associated neck pain and headache, Guillain-Barré syndrome, transverse myelitis, acute brachial plexus neuritis, and ocular myasthenia gravis.

Conclusions

Checkpoint inhibitor therapy remains a success story; however, neurological immune-related adverse events may cause severe life-threatening conditions. We propose a guide for the early detection of neurological adverse events during routine clinical treatment to prevent more severe courses of checkpoint inhibitor-induced neurotoxicity.

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We present neurological immune-related adverse events under checkpoint-inhibitors to underline the spectrums of manifestations.

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Neurological immune-related adverse events may cause severe life-threatening conditions.

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Practitioners should be aware of red flags symptoms to detect neurological immune-related adverse events

Overlapping central and peripheral nervous system syndromes in MOG antibody-associated disorders

Objective

Antibodies to myelin oligodendrocyte glycoprotein (MOG) are associated with CNS demyelination inclusive of optic neuritis (ON) and transverse myelitis (TM). To examine whether peripheral nervous system (PNS) involvement is associated with MOG antibody–associated disorders (MOGAD), we performed detailed characterization of an Australasian MOGAD cohort.

Methods

Using a live cell–based assay, we diagnosed 271 adults with MOGAD (2013–2018) and performed detailed clinical and immunologic characterization on those with likely PNS involvement.

Results

We identified 19 adults with MOGAD and PNS involvement without prior TM. All patients had CNS involvement including ON (bilateral [n = 3], unilateral [n = 3], and recurrent [n = 7]), a cortical lesion (n = 1), meningoencephalitis (n = 1), and subsequent TM (n = 4). Clinical phenotyping and neurophysiology were consistent with acute inflammatory demyelinating polyneuropathy (n = 1), myeloradiculitis (n = 3), multifocal motor neuropathy (n = 1), brachial neuritis (n = 2), migrant sensory neuritis (n = 3), and paresthesia and/or radicular limb pain (n = 10). Onset MRI spine was consistent with myeloradiculitis with nerve root enhancement in 3/19 and normal in 16/19. Immunotherapy resulted in partial/complete PNS symptom resolution in 12/15 (80%) (steroids and/or IV immunoglobulin n = 9, rituximab n = 2, and plasmapheresis n = 1). We identified serum antibodies targeting neurofascin 155, contactin-associated protein 2, or GM1 in 4/16 patients with MOGAD PNS compared with 0/30 controls (p = 0.01). There was no binding to novel cell surface antigens using an in vitro myelinating sensory neuronal coculture model.

Conclusions

Myeloradiculitis, combined central and peripheral demyelination syndromes, and inflammatory neuropathies may be associated with MOGAD and may be immunotherapy responsive. We identified a subgroup who may have pathology mediated by coexistent autoantibodies.

Neurologic Complications of Immune Checkpoint Inhibitors in Thoracic Malignancies

Immune checkpoint inhibitors (ICIs) have transformed the prognosis of cancers previously considered lethal. The spectrum of therapeutic indications is rapidly expanding, including the vast majority of thoracic malignancies. By enhancing the immune responses against cancer, the ICI treatments lead to the development of immune-related adverse events (irAEs) that may affect any organ. Severity varies from mild to fatal clinical manifestations. Neurologic involvement is relatively rare and highly heterogeneous, including central and peripheral nervous system diseases associated with neural-specific autoantibodies or not, central nervous system vasculitis, and granulomatous and demyelinating disorders. Symptoms often manifest within the first four cycles of treatment and can develop regardless of the class of ICI used. An unfavorable outcome is found in up to one-third of patients and is generally associated with the patients' clinical characteristics (e.g., age, coexistence of systemic adverse events), cancer type (e.g., lung cancer versus other), and specific clinical setting (e.g., ICI treatment in patients with preexisting paraneoplastic neurologic autoimmunity, ICI rechallenge after a first neurologic irAE). Diagnosis should be suspected in patients with new-onset neurologic symptoms while on ICI treatment which are not explained by metastatic disease or other metabolic/infectious disorders. Recommended treatment is based on clinical severity and consists of ICI discontinuation with or without immunosuppressive/immunomodulatory therapy, although alternative approaches are reasonable depending on cancer status (e.g., aggressive immunosuppression without discontinuing ICI in patients with initial cancer response). Early recognition and appropriate treatment of these neurologic irAEs are crucial for improved patient outcomes and therapeutic planning.

Neuro-ophthalmic Complications of Immune Checkpoint Inhibitors: A Systematic Review

OBJECTIVE

Immune checkpoint inhibitors (ICIs) are novel cancer therapies that may be associated with immune-related adverse events (IRAEs) and come to the attention of neuro-ophthalmologists. This systematic review aims to synthesize the reported ICI-associated IRAEs relevant to neuro-ophthalmologists to help in the diagnosis and management of these conditions.

METHODS

A systematic review of the literature indexed by MEDLINE, Embase, CENTRAL, and Web of Science databases was searched from inception to May 2020. Reporting followed the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) guidelines. Primary studies on ICIs and neuro-ophthalmic complications were included. Outcomes included number of cases and incidence of neuro-ophthalmic IRAEs.

RESULTS

Neuro-ophthalmic complications of ICIs occurred in 0.46% of patients undergoing ICI and may affect the afferent and efferent visual systems. Afferent complications include optic neuritis (12.8%), neuroretinitis (0.9%), and giant cell arteritis (3.7%). Efferent complications include myasthenia gravis (MG) (45.0%), thyroid-like eye disease (11.9%), orbital myositis (13.8%), general myositis with ptosis (7.3%), internuclear ophthalmoplegia (0.9%), opsoclonus-myoclonus-ataxia syndrome (0.9%), and oculomotor nerve palsy (0.9%). Pembrolizumab was the most common causative agent for neuro-ophthalmic complications (32.1%). Mortality was highest for MG (19.8%). Most patients (79.8%) experienced improvement or complete resolution of neuro-ophthalmic symptoms due to cessation of ICI and immunosuppression with systemic corticosteroids.

CONCLUSION

While incidence of neuro-ophthalmic IRAEs is low, clinicians involved in the care of cancer patients must be aware of their presentation to facilitate prompt recognition and management. Collaboration between oncology and neuro-ophthalmology teams is required to effectively manage patients and reduce morbidity and mortality.

Inflammatory Myeloradiculitis Secondary to Pembrolizumab: A Case Report and Literature Review

Immune checkpoint inhibitors are the most important new medications in oncology and include inhibitors of programmed cell death protein-1 (PD-1) such as Pembrolizumab, Nivolumab, and Cemiplimab. These anticancer agents prevent tumour immune evasion and have been associated with a range of immune-related adverse events (irAEs) including those involving the nervous system. In this case report and literature review, we present the first case of inflammatory myeloradiculitis secondary to Pembrolizumab. We also summarise the characteristics, treatment, and outcomes of other cases reported in the literature which include a component of myelitis. Finally, we make general recommendations on management.

Is neuromyelitis optica without AQP4-IgG a T-cell mediated disease? insights from checkpoint inhibitor immune-related adverse events

A 30-year-old female presented with recurrent opticospinal demyelinating attacks after introduction of nivolumab to treat Hodgkin's lymphoma. Paraneoplastic, neuronal surface, and demyelinating antibodies were negative from the serum and/or cerebrospinal fluid. Oligoclonal bands were negative and she met clinical criteria for NMOSD without AQP4-IgG. She could not tolerate plasmapheresis due to transfusion-related acute lung injury but responded well to corticosteroids and discontinuation of nivolumab. The precipitation of typical NMOSD without AQP4-IgG syndrome by a checkpoint inhibitor suggests a possible T-cell mediated pathogenesis. This may help explain why this patient group lacked response to B-cell therapies in NMOSD clinical trials.

Neurologic autoimmunity and immune checkpoint inhibitors: Autoantibody profiles and outcomes

OBJECTIVE

To describe neural autoantibody profiles and outcomes in patients with neurologic autoimmunity associated with immune checkpoint inhibitor (ICI) cancer immunotherapy.

METHODS

In this retrospective descriptive study, 63 patients with ICI-related neurologic autoimmunity were included: 39 seen at the Mayo Clinic Neurology Department (clinical cohort) and 24 whose serum/CSF was referred to the Mayo Clinic Neuroimmunology Laboratory for autoantibody testing. Serum/CSF samples were tested for neural-specific autoantibodies. Predictors of unfavorable outcome (residual adverse event severity grade ≥3) were explored (logistic regression).

RESULTS

Median age at neurologic symptom onset was 65 years (range 31-86); 40% were female. Neurologic manifestations were CNS-restricted (n = 26), neuromuscular (n = 30), combined (n = 5), or isolated retinopathy (n = 2). Neural-specific autoantibodies were common in patients with CNS involvement (7/13 [54%] in the unbiased clinical cohort) and included known or unidentified neural-restricted specificities. Only 11/31 patients with CNS manifestations had neuroendocrine malignancies typically associated with paraneoplastic autoimmunity. Small-cell lung cancer (SCLC)-predictive antibodies were seen in 3 patients with non-neuroendocrine tumors (neuronal intermediate filament immunoglobulin G [IgG] and antineuronal nuclear antibody 1 with melanoma; amphiphysin IgG with non-SCLC). A median of 10 months from onset (range, 0.5-46), 14/39 in the clinical cohort (36%) had unfavorable outcomes; their characteristics were age ≥70 years, female, CNS involvement, lung cancer, higher initial severity grade, and lack of systemic autoimmunity. By multivariate analysis, only age remained independently associated with poor outcome (p = 0.01). Four of 5 patients with preexistent neurologic autoimmunity experienced irreversible worsening after ICI.

CONCLUSIONS

Neural-specific autoantibodies are not uncommon in patients with ICI-related CNS neurologic autoimmunity. Outcomes mostly depend on the pre-ICI treatment characteristics and clinical phenotype.

Central nervous system complications associated with immune checkpoint inhibitors

OBJECTIVE

To describe the spectrum and outcome of central nervous system complications associated with immune checkpoint inhibitors (CNS-ICI).

METHODS

Patients with CNS-ICI were identified and their characteristics compared with ICI-related peripheral neuropathy (PN-ICI).

RESULTS

We identified 19 patients with CNS-ICI. The patients were receiving nivolumab (n=8), pembrolizumab (n=6), a combination of ipilimumab-nivolumab (n=3), ipilimumab-durvalumab (n=1), or atezolizumab (n=1). Underlying malignancies included non-small-cell lung cancer (n=8), melanoma (n=3), and other less common tumours (n=8). Neurological phenotypes were limbic encephalitis (n=8), meningoencephalitis (n=4) and cerebellitis (n=4). Two patients developed isolated confusion and one parkinsonism. Associated autoantibodies included onconeural (Ma2, n=7; Hu, n=1), astrocytic (glial fibrillar acidic protein, n=2) and neuronal surface (contactin-associated protein-like 2, n=1) specificities. ICIs were withheld and corticosteroid treatment was given in all cases. Five patients received intravenous immunoglobulin, two rituximab, one plasmapheresis and one infliximab. Overall, six patients died. Readministration of ICI was attempted in three patients, without further relapses. Non-small-cell lung cancer was significantly more frequent in patients with CNS-ICI (p<0.01), while melanoma and ipilimumab treatment were more common in PN-ICI (p<0.01 and p=0.01). Conversely, CNS-ICI cases were more frequently antibody-positive than PN-ICI (p<0.01) and showed a strong trend towards poorer outcome (p=0.053).

CONCLUSION

Three main clinical phenotypes characterise CNS complications of ICIs, each with distinct immunological background, disease course and response to treatment. Other clinical manifestations (including parkinsonism and steroid-responsive confusion) are also possible. Underlying cancers, antibody prevalence and outcome appear different from those of patients with PN-ICI.

Autoimmune encephalitis associated with Ma2 antibodies and immune checkpoint inhibitor therapy

Immune checkpoint inhibitors have transformed the treatment of advanced malignancy, while increasing the risk of immune-related adverse events. A 56-year-old woman who had received nivolumab for stage 4 renal cell carcinoma subsequently developed altered behaviour, memory deficits and worsening of previously stable epilepsy. MR scan of the brain showed bilateral FLAIR (fluid-attenuated inversion recovery) hyperintensity of the mesial temporal lobes, and there were anti-Ma2 antibodies in both serum and cerebrospinal fluid. She was treated with corticosteroids but developed further clinical relapses requiring immunoglobulin and rituximab. The immune-related adverse events relating to immune checkpoint inhibitors are an emerging challenge for the neurologist. Some cases are refractory and require serial immunosuppression.

Neurological Immune Related Adverse Events Associated with Nivolumab, Ipilimumab, and Pembrolizumab Therapy-Review of the Literature and Future Outlook

Immune checkpoint inhibitor (ICI) therapy has revolutionized the management of various cancers with previously poor prognosis. Despite its great efficacy, the therapy is associated with a wide spectrum of immune-related adverse events (irAE) including neurological symptoms which can affect all parts of the central and peripheral nervous system. Even though these events are rare, they are of high relevance as the rate of residual symptoms or even fatal outcomes is remarkable. To provide a detailed overview of neurological adverse events associated with immune checkpoint-inhibitor therapy we conducted a literature search. While focusing on ipilimumab, nivolumab, and pembrolizumab therapy, all available case reports as well as larger case series and clinical trials have been considered. Eighty-two case reports about checkpoint-inhibitor therapy induced symptoms of the peripheral nervous system have been published, while only 43 case reports addressed central nervous system abnormalities. The frequency of immune checkpoint-inhibitor therapy inducing neurological adverse events is about 1% in larger studies. Especially neuromuscular adverse events exhibit distinct clinical and diagnostic characteristics. Additionally, several affected patients presented with overlap-syndromes, which means that symptoms and diagnostic findings indicating myositis, myasthenia gravis, and neuropathy were present in one individual patient at the same time. Thus, neurological and particularly neuromuscular adverse events of immune checkpoint-inhibitor therapy may constitute a new disease entity.

Neurologic Autoimmunity in the Era of Checkpoint Inhibitor Cancer Immunotherapy

Neurologic autoimmune disorders in the context of systemic cancer reflect antitumor immune responses against onconeural proteins that are autoantigens in the nervous system. These responses observe basic principles of cancer immunity and are highly pertinent to oncological practice since the introduction of immune checkpoint inhibitor cancer therapy. The patient's autoantibody profile is consistent with the antigenic composition of the underlying malignancy. A major determinant of the pathogenic outcome is the anatomic and subcellular location of the autoantigen. IgGs targeting plasma membrane proteins (eg, muscle acetylcholine receptor -IgG in patients with paraneoplastic myasthenia gravis) have pathogenic potential. However, IgGs specific for intracellular antigens (eg, antineuronal nuclear antibody 1 [anti-Hu] associated with sensory neuronopathy and small cell lung cancer) are surrogate markers for CD8⁺ T lymphocytes targeting peptides derived from nuclear or cytoplasmic proteins. In an inflammatory milieu, those peptides translocate to neural plasma membranes as major histocompatibility complex class I protein complexes. Paraneoplastic neurologic autoimmunity can affect any level of the neuraxis and may be mistaken for cancer progression. Importantly, these disorders generally respond favorably to early-initiated immunotherapy and cancer treatment. Small cell lung cancer and thymoma are commonly associated with neurologic autoimmunity, but in the context of checkpoint inhibitor therapy, other malignancy associations are increasingly recognized.

Distinct HLA associations of LGI1 and CASPR2-antibody diseases

The recent biochemical distinction between antibodies against leucine-rich, glioma-inactivated-1 (LGI1), contactin-associated protein-2 (CASPR2) and intracellular epitopes of voltage-gated potassium-channels (VGKCs) demands aetiological explanations. Given established associations between human leucocyte antigen (HLA) alleles and adverse drug reactions, and our clinical observation of frequent adverse drugs reactions in patients with LGI1 antibodies, we compared HLA alleles between healthy controls (n = 5553) and 111 Caucasian patients with VGKC-complex autoantibodies. In patients with LGI1 antibodies (n = 68), HLA-DRB1*07:01 was strongly represented [odds ratio = 27.6 (95% confidence interval 12.9–72.2), P = 4.1 × 10⁻²⁶]. In contrast, patients with CASPR2 antibodies (n = 31) showed over-representation of HLA-DRB1*11:01 [odds ratio = 9.4 (95% confidence interval 4.6–19.3), P = 5.7 × 10⁻⁶]. Other allelic associations for patients with LGI1 antibodies reflected linkage, and significant haplotypic associations included HLA-DRB1*07:01-DQA1*02:01-DQB1*02:02, by comparison to DRB1*11:01-DQA1*05:01-DQB1*03:01 in CASPR2-antibody patients. Conditional analysis in LGI1-antibody patients resolved further independent class I and II associations. By comparison, patients with both LGI1 and CASPR2 antibodies (n = 3) carried yet another complement of HLA variants, and patients with intracellular VGKC antibodies (n = 9) lacked significant HLA associations. Within LGI1- or CASPR2-antibody patients, HLA associations did not correlate with clinical features. In silico predictions identified unique CASPR2- and LGI1-derived peptides potentially presented by the respective over-represented HLA molecules. These highly significant HLA associations dichotomize the underlying immunology in patients with LGI1 or CASPR2 antibodies, and inform T cell specificities and cellular interactions at disease initiation.

Blood Levels of Co-inhibitory-Receptors: A Biomarker of Disease Prognosis in Multiple Sclerosis

Background: The clinical course of multiple sclerosis ranges from benign with little disease progression and minimal disability, to severe disease requiring intensive medical treatment. There are no reliable circulating biomarkers for predicting disease outcome. Co-inhibitory receptors regulate the termination of effective immune responses to infections while limiting autoimmunity and/or immunopathology. Based on this, we studied the potential of circulating co-inhibitory receptor levels as predictive biomarkers of multiple sclerosis outcome.

Methods: Co-inhibitory receptor [TIGIT (T cell immunoreceptor with Ig and ITIM domains), TIM-3 (T-cell immunoglobulin and mucin domain–containing 3), LAG-3 (lymphocyte activation gene 3), PD-1 (programmed cell death 1), CTLA-4 (cytotoxic T-lymphocyte–associated protein 4)] expression levels in peripheral blood mononuclear cells (PBMCs) were measured using reverse transcription–PCR in 19 healthy controls and 57 patients with untreated multiple sclerosis. All patients were evaluated for disease outcome and paraclinical measures during the following 9–10 years [progression index, Expanded Disability Status Scale (EDSS) score, number of relapses, number of disease modifying therapies (DMTs), baseline brain magnetic resonance imaging T2 lesion volume, and oligoclonal bands (OCBs)].

Results: Patients had significantly lower TIGIT and LAG-3 levels than the controls (P < 0.02 and P < 0.04, respectively). TIM-3 levels were significantly lower in patients with high vs. low disability index and in patients with SPMS diagnosis compared to patients who remained in the relapsing stage of the disease at final visit (both, P < 0.02). LAG-3 levels were significantly higher in patients with low disability index vs. non-low disability index multiple sclerosis (P < 0.05). TIM-3 and LAG-3 expression levels correlated significantly with 1-year progression index (r² = 0.076, P < 0.05; 0.087, P < 0.04, respectively) and EDSS score at final visit (r² = 0.31, P < 0.04; 0.320.088, P < 0.04, respectively). Lower LAG-3 levels were associated with higher DMT switching (r² = 0.67, P < 0.05). Compared to the paraclinical and clinical parameters alone, the combined data of the baseline co-inhibitory receptor expression levels and the paraclinical and clinical parameters were superior for predicting the patients that would progress to secondary progressive multiple sclerosis (SPMS).

Interpretation: This is an initial exploration of the utility of CTLA-4, PD-1, TIM-3, LAG-3, and TIGIT expression levels as prognostic indicators in untreated, recently diagnosed multiple sclerosis. Our results support the value of decreased PBMC expression levels of TIM-3 and LAG-3 at diagnosis as an unfavorable prognostic factor, which is to be confirmed in further studies.

Severe pulmonary toxicity from immune checkpoint inhibitor treated successfully with intravenous immunoglobulin: Case report and review of the literature

Immune checkpoint inhibitors are known to cause a variety of immune-related adverse events, including pneumonitis. When symptomatic, treatment typically consists of temporary or permanent cessation of the checkpoint inhibitor and several weeks of corticosteroid therapy. However, a subset of patients may suffer from severe pneumonitis, and the optimal treatment for this group is not known. Here we describe the case of a patient receiving pembrolizumab for non-small cell lung cancer who developed severe checkpoint inhibitor pneumonitis. After treatment with high-dose corticosteroids failed to produce a response, a course of intravenous immunoglobulin catalyzed rapid and durable improvement. In this review, we discuss the current evidence regarding the incidence and outcomes of severe checkpoint inhibitor pneumonitis and propose a role for intravenous immunoglobulin as a possible treatment strategy.

Proposed diagnostic and treatment paradigm for high-grade neurological complications of immune checkpoint inhibitors

Immune checkpoint inhibitors such as antibodies to cytotoxic lymphocyte-associated protein 4 (ipilimumab) and programmed cell-death 1 (pembrolizumab, nivolumab) molecules have been used in non-small cell lung cancer, metastatic melanoma, and renal-cell carcinoma, among others. With these agents, immune-related adverse events (irAEs) can occur, including those affecting the neurological axis. In this review, high-grade neurological irAEs associated with immune checkpoint inhibitors including cases of Guillain-Barré syndrome (GBS) and myasthenia gravis (MG) are analyzed. Based on current literature and experience at our institution with 4 cases of high-grade neurological irAEs associated with immune checkpoint inhibitors (2 cases of GBS, 1 case of meningo-radiculitis, and 1 case of myelitis), we propose an algorithm for the investigation and treatment of high-grade neurological irAEs. Our algorithm incorporates both peripheral nervous system (meningo-radiculitis, GBS, MG) and central nervous system presentations (myelitis, encephalopathy). It is anticipated that our algorithm will be useful both to oncologists and neurologists who are likely to encounter neurological irAEs more frequently in the future as immune checkpoint inhibitors become more widely used.

The clinical features, underlying immunology, and treatment of autoantibody-mediated movement disorders

An increasing number of movement disorders are associated with autoantibodies. Many of these autoantibodies target the extracellular domain of neuronal surface proteins and associate with highly specific phenotypes, suggesting they have pathogenic potential. Below, we describe the phenotypes associated with some of these commoner autoantibody‐mediated movement disorders, and outline increasingly well‐established mechanisms of autoantibody pathogenicity which include antigen downregulation and complement fixation. Despite these advances, and the increasingly robust evidence for improved clinical outcomes with early escalation of immunotherapies, the underlying cellular immunology of these conditions has received little attention. Therefore, here, we outline the likely roles of T cells and B cells in the generation of autoantibodies, and reflect on how these may guide both current immunotherapy regimes and our future understanding of precision medicine in the field. In addition, we summarise potential mechanisms by which these peripherally‐driven immune responses may reach the central nervous system. We integrate this with the immunologically‐relevant clinical observations of preceding infections, tumours and human leucocyte antigen‐associations to provide an overview of the therapeutically‐relevant underlying adaptive immunology in the autoantibody‐mediated movement disorders. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.