Severe Neurological Toxicity of Immune Checkpoint Inhibitors: Growing Spectrum

Therapeutic Approach to Autoimmune Neurologic Disorders

OBJECTIVE

Autoimmune neurologic disorders encompass a broad category of diseases characterized by immune system attack of the central, peripheral, or autonomic nervous systems. This article provides information on both acute and maintenance immunotherapy used to treat autoimmune neurologic disorders as well as a review of symptomatic management and special considerations when caring for patients with these diseases.

LATEST DEVELOPMENTS

Over the past 20 years, more than 50 antibodies have been identified and associated with autoimmune neurologic disorders. Although advances in diagnostic testing have allowed for more rapid diagnosis, the therapeutic approach to these disorders has largely continued to rely on expert opinion, case series, and case reports. With US Food and Drug Administration (FDA) approval of biologic agents to treat neuromyelitis optica spectrum disorder (NMOSD) and myasthenia gravis as well as ongoing clinical trials for the treatment of autoimmune encephalitis, the landscape of immunotherapy options continues to expand. Consideration of the unique pathogenesis of individual autoimmune neurologic disorders as well as the mechanism of action of the diverse range of treatment options can help guide treatment decisions today while evidence from clinical trials informs new therapeutics in the future.

ESSENTIAL POINTS

Recognizing patients who have a clinical history and examination findings concerning for autoimmune neurologic disorders and conducting a thorough and directed imaging and laboratory evaluation aimed at ruling out mimics, identifying specific autoimmune syndromes, and screening for factors that may have an impact on immunotherapy choices early in the clinical course are essential to providing optimal care for these patients. Providers must consider immunotherapy, symptomatic treatment, and a multidisciplinary approach that addresses each patient's unique needs when treating patients with autoimmune neurologic disorders.

Harnessing the capacity of phytochemicals to enhance immune checkpoint inhibitor therapy of cancers: A focus on brain malignancies

Brain cancers, particularly glioblastoma multiforme (GBM), are challenging health issues with frequent unmet aspects. Today, discovering safe and effective therapeutic modalities for brain tumors is among the top research interests. Immunotherapy is an emerging area of investigation in cancer treatment. Since immune checkpoints play fundamental roles in repressing anti-cancer immunity, diverse immune checkpoint inhibitors (ICIs) have been developed, and some monoclonal antibodies have been approved clinically for particular cancers; nevertheless, there are significant concerns regarding their efficacy and safety in brain tumors. Among the various tools to modify the immune checkpoints, phytochemicals show good effectiveness and excellent safety, making them suitable candidates for developing better ICIs. Phytochemicals regulate multiple immunological checkpoint-related signaling pathways in cancer biology; however, their efficacy for clinical cancer immunotherapy remains to be established. Here, we discussed the involvement of immune checkpoints in cancer pathology and summarized recent advancements in applying phytochemicals in modulating immune checkpoints in brain tumors to highlight the state-of-the-art and give constructive prospects for future research.

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.

Neuro-oncologic Emergencies

OBJECTIVE

Neuro-oncologic emergencies have become more frequent as cancer remains one of the leading causes of death in the United States, second only to heart disease. This article highlights key aspects of epidemiology, diagnosis, and management of acute neurologic complications in primary central nervous system malignancies and systemic cancer, following three thematic classifications: (1) complications that are anatomically or intrinsically tumor-related, (2) complications that are tumor-mediated, and (3) complications that are treatment-related.

LATEST DEVELOPMENTS

The main driver of mortality in patients with brain metastasis is systemic disease progression; however, intracranial hypertension, treatment-resistant seizures, and overall decline due to increased intracranial burden of disease are the main factors underlying neurologic-related deaths. Advances in the understanding of tumor-specific characteristics can better inform risk stratification of neurologic complications. Following standardized grading and management algorithms for neurotoxic syndromes related to newer immunologic therapies is paramount to achieving favorable outcomes.

ESSENTIAL POINTS

Neuro-oncologic emergencies span the boundaries of subspecialties in neurology and require a broad understanding of neuroimmunology, neuronal hyperexcitability, CSF flow dynamics, intracranial compliance, and neuroanatomy.

Immune Checkpoint Inhibitor-Induced Guillain Barre Syndrome: A Single-Institution Case Report and Narrative Review

Guillain-Barré syndrome (GBS) resulting from the use of immune checkpoint inhibitors (ICIs) is relatively uncommon but has been reported. Herein, we discuss a case of a 67-year-old patient who received neoadjuvant ICI for treatment of non-small cell lung cancer and then presented with lower extremity weakness and areflexia, progressing to respiratory muscle and upper extremity weakness. Given the increasing use of ICI in cancer management, awareness of neurological autoimmune side effects is essential. ICI-mediated GBS can be severe and fatal if not diagnosed promptly. We discuss a case of ICI-induced GBS and review literature on current management approaches.

Advancements and prospects of novel biologicals for myasthenia gravis: toward personalized treatment based on autoantibody specificities

Myasthenia gravis (MG) is an antibody-mediated autoimmune disease with a prevalence of 150-250 cases per million individuals. Autoantibodies include long-lived antibodies against the acetylcholine receptor (AChR), mainly of the IgG1 subclass, and IgG4, produced almost exclusively by short-lived plasmablasts, which are prevalent in muscle-specific tyrosine kinase (MuSK) myasthenia gravis. Numerous investigations have demonstrated that MG patients receiving conventional medication today still do not possess satisfactory symptom control, indicating a substantial disease burden. Subsequently, based on the type of the autoantibody and the pathogenesis, we synthesized the published material to date and reached a conclusion regarding the literature related to personalized targeted therapy for MG. Novel agents for AChR MG have shown their efficacy in clinical research, such as complement inhibitors, FcRn receptor antagonists, and B-cell activating factor (BAFF) inhibitors. Rituximab, a representative drug of anti-CD20 therapy, has demonstrated benefits in treatment of MuSK MG patients. Due to the existence of low-affinity antibodies or unidentified antibodies that are inaccessible by existing methods, the treatment for seronegative MG remains complicated; thus, special testing and therapy considerations are necessary. It may be advantageous to initiate the application of novel biologicals at an early stage of the disease. Currently, therapies can also be combined and individualized according to different types of antibodies. With such a wide range of drugs, how to tailor treatment strategies to patients with various conditions and find the most suitable solution for each MG profile are our necessary and urgent aims.

Clinical drug screening reveals clofazimine potentiates the efficacy while reducing the toxicity of anti-PD-1 and CTLA-4 immunotherapy

Emerging as the most potent and durable combinational immunotherapy, dual anti-PD-1 and CTLA-4 immune checkpoint blockade (ICB) therapy notoriously increases grade 3-5 immune-related adverse events (irAEs) in patients. Accordingly, attempts to improve the antitumor potency of anti-PD-1+CTLA-4 ICB by including additional therapeutics have been largely discouraged due to concerns of further increasing fatal toxicity. Here, we screened ∼3,000 Food and Drug Administration (FDA)-approved drugs and identified clofazimine as a potential third agent to optimize anti-PD-1+CTLA-4 ICB. Remarkably, clofazimine outperforms ICB dose reduction or steroid treatment in reversing lethality of irAEs, but unlike the detrimental effect of steroids on antitumor efficacy, clofazimine potentiates curative responses in anti-PD-1+CTLA-4 ICB. Mechanistically, clofazimine promotes E2F1 activation in CD8+ T cells to overcome resistance and counteracts pathogenic Th17 cells to abolish irAEs. Collectively, clofazimine potentiates the antitumor efficacy of anti-PD-1+CTLA-4 ICB, curbs intractable irAEs, and may fill a desperate clinical need to improve patient survival.

Immune Checkpoint Inhibitor-Associated Kelch-Like Protein-11 IgG Brainstem Encephalitis

OBJECTIVES

Kelch-like protein-11 (KLHL11)-IgG is associated with rhombencephalitis and seminoma. It has not previously been described as a neurologic immune checkpoint inhibitor (ICI)-related adverse event (nirAE) or in association with esophageal adenocarcinoma.

METHODS

We describe a 61-year-old man with metastatic esophageal adenocarcinoma treated with folinic acid, fluorouracil, oxaliplatin (FOLFOX), and nivolumab, who subsequently developed diplopia, vertigo, and progressive gait ataxia after 8 weeks of treatment.

RESULTS

Owing to a concern for ICI-associated myasthenia gravis, nivolumab was held and he was treated with prednisone and pyridostigmine. EMG showed no neuromuscular junction dysfunction, and acetylcholine-receptor antibodies were negative. Brain MRI was unrevealing. Murine brain tissue immunofluorescence assay revealed KLHL11-IgG in both serum and CSF, confirmed by cell-based assay. Tumor histopathology demonstrated poorly differentiated, highly proliferative adenocarcinoma with increased mitotic figures and cytoplasmic KLHL11 immunoreactivity. He was initiated on 6 months of cyclophosphamide in addition to FOLFOX for post-ICI-associated KLHL11-IgG rhombencephalitis.

DISCUSSION

We report KLHL11-IgG rhombencephalitis associated with poorly differentiated esophageal cancer as a novel nirAE. Tumor staining revealed KLHL11 immunoreactivity, supporting a cancer-antigen-driven ICI-associated paraneoplastic syndrome. Recognition of novel nirAEs can expedite treatment and potentially prevent progressive neurologic disability.

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.

Immune-Related Adverse Events Due to Cancer Immunotherapy: Immune Mechanisms and Clinical Manifestations

The landscape of cancer treatment has undergone a significant transformation with the introduction of Immune Checkpoint Inhibitors (ICIs). Patients undergoing these treatments often report prolonged clinical and radiological responses, albeit with a potential risk of developing immune-related adverse events (irAEs). Here, we reviewed and discussed the mechanisms of action of ICIs and their pivotal role in regulating the immune system to enhance the anti-tumor immune response. We scrutinized the intricate pathogenic mechanisms responsible for irAEs, arising from the evasion of self-tolerance checkpoints due to drug-induced immune modulation. We also summarized the main clinical manifestations due to irAEs categorized by organ types, detailing their incidence and associated risk factors. The occurrence of irAEs is more frequent when ICIs are combined; with neurological, cardiovascular, hematological, and rheumatic irAEs more commonly linked to PD1/PD-L1 inhibitors and cutaneous and gastrointestinal irAEs more prevalent with CTLA4 inhibitors. Due to the often-nonspecific signs and symptoms, the diagnosis of irAEs (especially for those rare ones) can be challenging. The differential with primary autoimmune disorders becomes sometimes intricate, given the clinical and pathophysiological similarities. In conclusion, considering the escalating use of ICIs, this area of research necessitates additional clinical studies and practical insights, especially the development of biomarkers for predicting immune toxicities. In addition, there is a need for heightened education for both clinicians and patients to enhance understanding and awareness.

Dataset for: Autoantibody profiles in patients with immune checkpoint inhibitor-induced neurological immune-related adverse events

The rise of cancer immunotherapy has been a milestone in clinical oncology. Above all, immune checkpoint inhibitor treatment (ICI) with monoclonal antibodies targeting programmed cell death protein 1 (PD-1), programmed cell death-ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) has improved survival rates for an increasing number of malignancies. However, despite the clinical benefits, ICI-related autoimmunity has become a significant cause of non-relapse-related morbidity and mortality. Neurological immune-related adverse events (irAE-n) are particularly severe toxicities with a high risk for chronic illness, long-term steroid dependency, and early ICI treatment termination. While the clinical characteristics of irAE-n are well described, little is known about underlying immune mechanisms and potential biomarkers. Recently, high frequencies of neuronal autoantibodies in patients with irAE-n have been reported, however, their clinical relevance is unclear. Here, we present a dataset on neuronal autoantibody profiles in ICI-treated cancer patients with and without irAE-n, which was generated to investigate the potential role of neuronal autoantibodies in ICI-induced autoimmunity. Between September 2017 and January 2022 serum samples of 29 cancer patients with irAE-n post-ICI treatment) and 44 cancer control patients without high-grade immune-related adverse events (irAEs, n = 44 pre- and post-ICI treatment) were collected and tested for a large panel of brain-reactive and neuromuscular autoantibodies using indirect immunofluorescence and immunoblot assays. Prevalence of autoantibodies was compared between the groups and correlated with clinical characteristics such as outcome and irAE-n manifestation. These data represent the first systematic comparison of neuronal autoantibody profiles between ICI-treated cancer patients with and without irAE-n, providing valuable information for both researchers and clinicians. In the future, this dataset may be valuable for meta-analyses on the prevalence of neuronal autoantibodies in cancer patients.

Immune checkpoint inhibitor-related myositis and myocarditis: diagnostic pitfalls and imaging contribution in a real-world, institutional case series

BACKGROUND

Immune checkpoint inhibitors (ICIs) are reshaping the prognosis of many cancers, but often cause immune-related adverse events (irAEs). Among neurological irAEs, myositis is the most frequently reported. Our aim is to describe clinical and non-clinical characteristics, treatment and outcome of all irMyositis (skeletal limb-girdle and/or ocular myositis) and irMyocarditis cases in our reference center.

METHODS

We retrospectively enrolled all irMyositis/irMyocarditis patients seen between 2018 and 2022. We reviewed demographics, clinical characteristics, biological, neurophysiological, imaging workup, treatment and outcome.

RESULTS

We included 14 consecutive patients. The most frequent treatments were pembrolizumab (35%) or ipilimumab-nivolumab combination (35%). Limb-girdle, ocular (non-fluctuating palpebral ptosis and/or diplopia with or without ophthalmoparesis) and cardiac phenotypes were equally distributed, overlapping in 40% of cases. Ocular involvement was frequently misdiagnosed; review of brain MRIs disclosed initially missed signs of skeletal myositis in one patient and ocular myositis in 3. Seven patients had other co-existing irAEs. When performed, myography showed a myogenic pattern. CK was elevated in 8/15 patients, troponin-T in 12/12 and troponin-I in 7/9 tested patients. ICI were discontinued in all cases, with further immunosuppressive treatment in nine patients. In most cases, neurological and cardiological outcome was good at last follow-up.

CONCLUSION

Myositis is a potentially severe irAE. Despite its heterogeneous presentation, some highly suggestive clinical symptoms, such as ocular involvement, or radiological signs should raise physicians' attention to avoid misdiagnosis. We thus recommend a multidisciplinary assessment (including complete neuromuscular evaluation) even in case of isolated myocarditis. Our series underlines the importance of an early diagnosis, since suspension of ICI and adequate treatment are usually associated with good functional outcome.

Iatrogenic affectation of ocular motility by immune checkpoint inhibitors

Cancer therapy relies on new antitumoral drugs called immune checkpoint inhibitors (ICI), which produce long-lasting anti-tumor responses and lengthen survival, but cause autoimmune-type toxicity. The clinical characteristics induced by ICI are not well characterized to date and careful collection of clinical data is required to accurately define its safety profile. We conducted a literature search in the main clinical search engines to identify pharmacological ocular iatrogenic events of ICIs related to ocular motility. Four systematic reviews were found that included this type of ocular iatrogenesis as well as numerous isolated case reports. Reported adverse effects include: oculomotor paresis, optic neuropathy, optic atrophy, myastheniform syndromes, thyroid pseudo-orbitopathy, orbital apex syndrome, and hypophysitis. Most were managed without interruption or with partial interruption of cancer treatment. Aggressive systemic treatments were required for adequate management of ocular iatrogenic events. It is essential that the ophthalmologist become familiar with the new ICI oncological treatments, capable of causing severe and disabling motilidad ocular iatrogenesis for the patient. The communication of adverse effects and the report of the treatments used can help the most appropriate management of these patients. Research should be oriented towards complex differential diagnosis and to optimize decisions on cancer treatments.

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

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

Synergistic effects of immune checkpoints and checkpoint inhibitors in inflammatory neuropathies: Implications and mechanisms

Immune checkpoint molecules play pivotal roles in the regulation of immune homeostasis. Disruption of the immune checkpoints causes autoimmune/inflammatory as well as malignant disorders. Over the past few years, the immune checkpoint molecules with inhibitory function emerged as potential therapeutic targets in oncological conditions. The inhibition of the function of these molecules by using immune checkpoint inhibitors (ICIs) has brought paradigmatic changes in cancer therapy due to their remarkable clinical benefits, not only in improving the quality of life but also in prolonging the survival time of cancer patients. Unfortunately, the ICIs soon turned out to be a "double-edged sword" as the use of ICIs caused multiple immune-related adverse effects (irAEs). The development of inflammatory neuropathies such as Guillain-Barré syndrome (GBS) and Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP) as the secondary effects of immunotherapy appeared very challenging as these conditions result in significant and often permanent disability. The underlying mechanism(s) through which ICIs trigger inflammatory neuropathies are currently not known. Compelling evidence suggests autoimmune reaction and/or inflammation as the independent risk mechanism of inflammatory neuropathies. There is a lack of understanding as to whether prior exposure to the risk factors of inflammatory neuropathies, the presence of germline genetic variants in immune function-related genes, genetic variations within immune checkpoint molecules, the existence of autoantibodies, and activated/memory T cells act as determining factors for ICI-induced inflammatory neuropathies. Herein, we highlight the available pieces of evidence, discuss the mechanistic basis, and propose a few testable hypotheses on inflammatory neuropathies as irAEs of immunotherapy.

Achilles' Heel of currently approved immune checkpoint inhibitors: immune related adverse events

Immunotherapy has revolutionized the cancer treatment landscape by opening up novel avenues for intervention. As the use of immune checkpoint inhibitors (ICIs) has exponentially increased, so have immune-related adverse events (irAEs). The mechanism of irAEs may involve the direct damage caused by monoclonal antibodies and a sequence of immune responses triggered by T cell activation. Common side effects include dermatologic toxicity, endocrine toxicity, gastrointestinal toxicity, and hepatic toxicity. While relatively rare, neurotoxicity, cardiotoxicity, and pulmonary toxicity can be fatal. These toxicities pose a clinical dilemma regarding treatment discontinuation since they can result in severe complications and necessitate frequent hospitalization. Vigilant monitoring of irAEs is vital in clinical practice, and the principal therapeutic strategy entails the administration of oral or intravenous glucocorticoids (GSCs). It may be necessary to temporarily or permanently discontinue the use of ICIs in severe cases. Given that irAEs can impact multiple organs and require diverse treatment approaches, the involvement of a multidisciplinary team of experts is imperative. This review aims to comprehensively examine the pathogenesis, clinical manifestations, incidence, and treatment options for various irAEs.

Immune signatures of checkpoint inhibitor-induced autoimmunity-A focus on neurotoxicity

BACKGROUND

Neurologic immune-related adverse events (irAE-n) are rare but severe toxicities of immune checkpoint inhibitor (ICI) treatment. To overcome diagnostic and therapeutic challenges, a better mechanistic understanding of irAE-n is paramount.

METHODS

In this observational cohort study, we collected serum and peripheral blood samples from 34 consecutive cancer patients with irAE-n (during acute illness) and 49 cancer control patients without irAE-n (pre- and on-ICI treatment, n = 44 without high-grade irAEs, n = 5 with high-grade nonneurologic irAEs). Patients received either anti-programmed cell death protein (PD)-1 or anti-PD ligand-1 monotherapy or anti-PD-1/anti-cytotoxic T-lymphocyte-associated protein-4 combination therapy. Most common cancers were melanoma, lung cancer, and hepatocellular carcinoma. Peripheral blood immune profiling was performed using 48-marker single-cell mass cytometry and a multiplex cytokine assay.

RESULTS

During acute illness, patients with irAE-n presented higher frequencies of cluster of differentiation (CD)8+ effector memory type (EM-)1 and central memory (CM) T cells compared to controls without irAEs. Multiorgan immunotoxicities (neurologic + nonneurologic) were associated with higher CD8+ EM1 T cell counts. While there were no B cell changes in the overall cohort, we detected a marked decrease of IgD- CD11c+ CD21low and IgD- CD24+ CD21high B cells in a subgroup of patients with autoantibody-positive irAE-n. We further identified signatures indicative of enhanced chemotaxis and inflammation in irAE-n patients and discovered C-X-C motif chemokine ligand (CXCL)10 as a promising marker to diagnose high-grade immunotoxicities such as irAE-n.

CONCLUSIONS

We demonstrate profound and partly subgroup-specific immune cell dysregulation in irAE-n patients, which may guide future biomarker development and targeted treatment approaches.

Concentrations of S100B and neurofilament light chain in blood as biomarkers for checkpoint inhibitor-induced CNS inflammation

BACKGROUND

Cancer treatment with immune checkpoint inhibition (ICI) can cause immune-related adverse events in the central nervous system (CNS irAE). There are no blood biomarkers to detect CNS irAE. We investigated if concentrations of S100-calcium-binding protein B (S100B) and neurofilament light chain (NfL) in blood can be used as biomarkers for CNS irAE and assessed the incidence of CNS irAE in a cohort of ICI-treated patients.

METHODS

In this single-centre, retrospective cohort study, we examined medical records and laboratory data of 197 consecutive patients treated with combined CTLA-4 and PD-1 inhibition (ipilimumab; ipi + nivolumab; nivo) for metastatic melanoma or renal cell carcinoma. CNS irAE was diagnosed using established criteria. Concentrations of S100B and NfL in blood were measured in patients with CNS irAE and in 84 patients without CNS irAE.

FINDINGS

Nine of 197 patients (4.6%) fulfilled criteria for CNS irAE. S100B and NfL in blood increased during CNS inflammation and normalized during immunosuppression. CNS irAE was detected with a sensitivity of 100% (S100B) and 79% (NfL) and a specificity of 89% (S100B) and 74% (NfL). Patients with CNS irAE had simultaneous increased concentration of C-reactive protein (CRP) (9/9) and alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) in blood (8/9).

INTERPRETATION

Analysis of S100B, NfL and CRP in blood facilitates the diagnosis of CNS irAE. CNS irAE may be more common than previously reported. There may be shared immune mechanisms between CNS and hepatitis irAE.

FUNDING

Supported by funding from the Swedish Cancer Foundation, the ALF-agreement, and Jubileumsklinikens Cancerfond.

Mononeuritis multiplex following immune checkpoint inhibitors in malignant pleural mesothelioma

Introduction

Mononeuritis multiplex is frequently related to vasculitic neuropathy and has been reported only sporadically as an adverse event of immune checkpoint inhibitors.

Methods

Case series of three patients with mononeuritis multiplex-all with mesothelioma-identified in the databases of two French clinical networks (French Reference Center for Paraneoplastic Neurological Syndromes, Lyon; OncoNeuroTox, Paris; January 2015-October 2022) set up to collect and investigate n-irAEs on a nationwide level.

Results

Three patients (male; median age 86 years; range 72-88 years) had pleural mesothelioma and received 10, 4, and 6 cycles, respectively, of first-line nivolumab plus ipilimumab combined therapy. In patient 1, the neurological symptoms involved the median nerves, and in the other two patients, there was a more diffuse distribution; the symptoms were severe (common terminology criteria for adverse events, CTCAE grade 3) in all patients. Nerve conduction studies indicated mononeuritis multiplex in all patients. Peripheral nerve biopsy demonstrated necrotizing vasculitis in patients 1 and 3 and marked IgA deposition without inflammatory lesions in patient 2. Immune checkpoint inhibitors were permanently withdrawn, and corticosteroids were administered to all patients, leading to complete symptom regression (CTCAE grade 0, patient 2) or partial improvement (CTCAE grade 2, patients 1 and 3). During steroid tapering, patient 1 experienced symptom recurrence and spreading to other nerve territories (CTCAE grade 3); he improved 3 months after rituximab and cyclophosphamide administration.

Discussion

We report the occurrence of mononeuritis multiplex, a very rare adverse event of immune checkpoint inhibitors, in the three patients with mesothelioma. Clinicians must be aware of this severe, yet treatable adverse event.

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.

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.

Hematologic malignancies and hematopoietic stem cell transplantation

Paraneoplastic neurologic syndromes are rarely associated with hematologic malignancies. In their rarity, lymphomas are the diseases with more frequent paraneoplastic neurologic syndrome. High-risk antibodies are absent in most lymphoma-associated paraneoplastic neurologic syndromes, with the exception of antibodies to Tr/DNER in paraneoplastic cerebellar degeneration, mGluR5 in limbic encephalitis, and mGluR1 in some cerebellar ataxias. Peripheral nervous system paraneoplastic neurologic syndromes are rare and heterogeneous, with a prevalence of demyelinating polyradiculoneuropathy in non-Hodgkin lymphoma. Polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes (POEMS) is a rare, paraneoplastic syndrome due to an underlying plasma cell disorder. The diagnosis is based on defined criteria, and vascular endothelial growth factor (VEGF), not an antibody, is considered a reliable diagnostic marker that also mirrors therapy response. As with the paraneoplastic neurologic syndromes in solid tumors, therapies rely on cancer treatment associated with immunomodulatory treatment with better response in PNS with antibodies to surface antigens. The best outcome is generally present in Ophelia syndrome/limbic encephalitis with anti-mGluR5 antibodies, with frequent complete recovery. Besides patients with isolated osteosclerotic lesions (where radiotherapy is indicated), hematopoietic stem-cell transplantation is the therapy of choice in patients with POEMS syndrome. In the paraneoplastic neurologic syndromes secondary to immune checkpoint inhibitors, discontinuation of the drug together with immunomodulatory treatment is recommended.

Paraneoplastic neuropathies and peripheral nerve hyperexcitability disorders

Peripheral neuropathy is a common referral for patients to the neurologic clinics. Paraneoplastic neuropathies account for a small but high morbidity and mortality subgroup. Symptoms include weakness, sensory loss, sweating irregularity, blood pressure instability, severe constipation, and neuropathic pain. Neuropathy is the first presenting symptom of malignancy among many patients. The molecular and cellular oncogenic immune targets reside within cell bodies, axons, cytoplasms, or surface membranes of neural tissues. A more favorable immune treatment outcome occurs in those where the targets reside on the cell surface. Patients with antibodies binding cell surface antigens commonly have neural hyperexcitability with pain, cramps, fasciculations, and hyperhidrotic attacks (CASPR2, LGI1, and others). The antigenic targets are also commonly expressed in the central nervous system, with presenting symptoms being myelopathy, encephalopathy, and seizures with neuropathy, often masked. Pain and autonomic components typically relate to small nerve fiber involvement (nociceptive, adrenergic, enteric, and sudomotor), sometimes without nerve fiber loss but rather hyperexcitability. The specific antibodies discovered help direct cancer investigations. Among the primary axonal paraneoplastic neuropathies, pathognomonic clinical features do not exist, and testing for multiple antibodies simultaneously provides the best sensitivity in testing (AGNA1-SOX1; amphiphysin; ANNA-1-HU; ANNA-3-DACH1; CASPR2; CRMP5; LGI1; PCA2-MAP1B, and others). Performing confirmatory antibody testing using adjunct methods improves specificity. Antibody-mediated demyelinating paraneoplastic neuropathies are limited to MAG-IgM (IgM-MGUS, Waldenström's, and myeloma), with the others associated with cytokine elevations (VEGF, IL6) caused by osteosclerotic myeloma, plasmacytoma (POEMS), and rarely angiofollicular lymphoma (Castleman's). Paraneoplastic disorders have clinical overlap with other idiopathic antibody disorders, including IgG4 demyelinating nodopathies (NF155 and Contactin-1). This review summarizes the paraneoplastic neuropathies, including those with peripheral nerve hyperexcitability.

Incidence and Outcome of Neurologic Immune-Related Adverse Events Associated With Immune Checkpoint Inhibitors in Patients With Melanoma

BACKGROUND AND OBJECTIVES

Neurologic immune-related adverse events (n-irAEs) reportedly occur in up to 8% of patients treated with immune checkpoint inhibitors (ICIs) of all age groups. We investigated the association between age and n-irAEs in patients treated with ICIs and examined the effect of n-irAEs on survival outcomes in a large cohort of patients with melanoma.

METHODS

We conducted a retrospective analysis of patients with advanced melanoma treated with ICIs at Ella Institute for Immuno-oncology and Melanoma between January 1, 2015, and April 20, 2022. The outcomes of interest were defined as the investigation of age-related frequency and severity of n-irAEs, the need for ICI interruption, the treatment required for n-irAE management, the safety of ICI reintroduction, and n-irAE's effect on survival.

RESULTS

ICI was administered to 937 patients. At least one irAE occurred in 73.5% (n = 689) of them. Among the study population, 8% (n = 76) developed a n-irAE, with a median age of 66 years in female and 68 years in male patients at onset. The median follow-up after n-irAE was 1,147 days (IQR: 1,091.5 range: 3,938). Fewer irAEs occurred in patients older than 70 years (median: 3 events, p = 0.04, CI 2.5-4.7) while specifically colitis and pneumonitis were more common in the 18-60 age group (p = 0.03, 95% CI 0.8-0.38, p = 0.009, 95% CI 0.06-0.2). Grade ≥ 3 toxicity was seen in 35.5% of patients across age groups. The median time from ICI administration to n-irAE development was 48 days across age groups. Common n-irAE phenotypes were myositis (44.7%), encephalitis (10.5%), and neuropathy (10.5%). N-irAE required hospitalization in 40% of patients and steroids treatment in 46% with a median of 4 days from n-irAE diagnosis to steroids treatment initiation. Nine patients needed second-line immunosuppressive treatment. Rechallenge did not cause additional n-irAE in 71% of patients. Developing n-irAE (HR = 0.4, 95% CI 0.32-0.77) or any irAE (HR = 0.7195% CI 0.56-0.88) was associated with longer survival.

DISCUSSION

N-irAEs are a relatively common complication of ICIs (8% of our cohort). Older age was not associated with its development or severity, in contrast with non-n-irAEs which occurred less frequently in the elderly population. Rechallenge did not result in life-threatening AEs. Development of any irAEs was associated with longer survival; this association was stronger with n-irAEs.

Neurotoxicity of Cancer Immunotherapies Including CAR T Cell Therapy

PURPOSE OF REVIEW

To outline the spectrum of neurotoxicity seen with approved immunotherapies and in pivotal clinical trials including immune checkpoint inhibitors, chimeric antigen receptor T-cell therapy, vaccine therapy, and oncolytic viruses.

RECENT FINDINGS

There has been an exponential growth in new immunotherapies, which has transformed the landscape of oncology treatment. With more widespread use of cancer immunotherapies, there have also been advances in characterization of its associated neurotoxicity, research into potential underlying mechanisms, and development of management guidelines. Increasingly, there is also mounting interest in long-term neurologic sequelae. Neurologic complications of immunotherapy can impact every aspect of the central and peripheral nervous system. Early recognition and treatment are critical. Expanding indications for immunotherapy to solid and CNS tumors has led to new challenges, such as how to reliably distinguish neurotoxicity from disease progression. Our evolving understanding of immunotherapy neurotoxicity highlights important areas for future research and the need for novel immunomodulatory therapeutics.

Neurological adverse events related to immune-checkpoint inhibitors in Spain: a retrospective cohort study

BACKGROUND

Neurological immune-related adverse events associated with immune checkpoint inhibitors can have several clinical manifestations, but the syndromes and prognostic factors are still not well known. We aimed to characterise and group the clinical features, with a special focus in patients presenting with encephalopathy, and to identify predictors of response to therapy and survival.

METHODS

This retrospective observational study included patients with neurological immune-related adverse events from 20 hospitals in Spain whose clinical information, serum samples, and CSF samples were studied at Hospital Clinic de Barcelona, Barcelona, Spain. Patients with pre-existing paraneoplastic syndromes or evidence of alternative causes for their neurological symptoms were excluded. We reviewed the clinical information, classified their clinical features, and determined the presence of neural antibodies. Neurological status was assessed by the treating physician one month after adverse event onset (as improvement vs no improvement) and at the last evaluation (complete recovery or modified Rankin Scale score decrease of at least 2 points, indicating good outcome, vs all other modified Rankin Scale scores, indicating poor outcome); if the participant had died, the date and cause of death were recorded. We used Fisher's exact tests and Mann-Whitney U tests to analyse clinical features, and multivariable logistic regression to analyse prognostic factors.

FINDINGS

From Jan 1, 2018, until Feb 1, 2023, 83 patients with suspected neurological immune-related adverse events after use of immune checkpoint inhibitors were identified, of whom 64 patients were included. These patients had a median age of 67 years (IQR 59-74); 42 (66%) were male and 22 (34%) were female. The predominant tumours were lung cancer (30 [47%] patients), melanoma (13 [21%] patients), and renal cell carcinoma (seven [11%] patients). Neural antibodies were detected in 14 (22%) patients; 52 (81%) patients had CNS involvement and 12 (19%) had peripheral nervous system involvement. Encephalopathy occurred in 45 (70%) patients, 12 (27%) of whom had antibodies or well defined syndromes consistent with definite paraneoplastic or autoimmune encephalitis, 24 (53%) of whom had encephalitis without antibodies or clinical features characteristic of a defined syndrome, and nine (20%) of whom had encephalopathy without antibodies or inflammatory changes in CSF or brain MRI. Nine (14%) of 64 patients had combined myasthenia and myositis, five of them with myocarditis. Even though 58 (91%) of 64 patients received steroids and 31 (48%) of 64 received additional therapies, 18 (28%) did not improve during the first month after adverse event onset, and 11 of these 18 people died. At the last follow-up for the 53 remaining patients (median 6 months, IQR 3-13), 20 (38%) had a poor outcome (16 deaths, one related to a neurological immune-related adverse event). Mortality risk was increased in patients with lung cancer (vs those with other cancers: HR 2·5, 95% CI 1·1-6·0) and in patients with encephalopathy without evidence of CNS inflammation or combined myocarditis, myasthenia, and myositis (vs those with the remaining syndromes: HR 5·0, 1·4-17·8 and HR 6·6, 1·4-31·0, respectively).

INTERPRETATION

Most neurological immune-related adverse events involved the CNS and were antibody negative. The presence of myocarditis, myasthenia, and myositis, of encephalopathy without inflammatory changes, or of lung cancer were independent predictors of death. Most deaths occurred during the first month of symptom onset. If our findings are replicated in additional cohorts, they could confirm that these patients need early and intensive treatment.

FUNDING

The Instituto de Salud Carlos III and the European Union.

Encephalitis in a patient with hypopharynx cancer treated with immune checkpoint inhibitors and radiotherapy: a case report and review of the literature

Hypopharyngeal cancer (HPC) has one of the most unfavorable prognoses among head and neck squamous cell carcinomas. Immunotherapy in combination with chemotherapy, the same as conventional induction chemotherapy, has emerged as a vital part of the induction therapy protocol for HPC. Meanwhile, the incidence of immune-related adverse events is increasing. In this light, we present the first reported case of immune-associated encephalitis in a patient with hypopharyngeal cancer treated with Camrelizumab (a PD-1 inhibitor). After receiving immunotherapy combined with chemotherapy as induction therapy, along with concurrent chemoradiotherapy, the patient presented with symptoms of fatigue, tremors, drowsiness, and an abnormal signal in the right temporal lobe as shown on a brain magnetic resonance imaging (MRI). Despite the minor elevation in protein and IgG index observed in the lumbar puncture, there is no evidence of abnormal autoantibodies or evidence of pathogenic infection. Following a thorough multidisciplinary consultation, the patient is suspected to be afflicted with immune-related autoimmune encephalitis. Intravenous methylprednisolone was prescribed as an empirical treatment at an initial dosage of 120 mg/day for 3 days, followed by steroid tapering. Finally, the patient experienced complete neurologic and radiographic (brain MRI) recovery. This case serves as a critical reminder that encephalitis is a potential diagnosis that should never be overlooked in patients undergoing immunotherapy who present with abnormal signs of the brain. The timely diagnosis and initiation of immunosuppressive therapy are key components of treating ICI-associated encephalitis.

Toxic Neuropathies

OBJECTIVE

The purpose of this article is to provide an overview and update on the most clinically relevant toxic neuropathies.

LATEST DEVELOPMENTS

Broadly, toxic neuropathies were previously quite rare with the notable exception of neuropathy from alcohol or older chemotherapeutics. The development of newer therapies, particularly immunotherapy to treat malignancy, has resulted in a substantial increase in the occurrence of toxic neuropathies that require timely recognition and treatment. The understanding of other toxic neuropathies continues to evolve, such as statin-induced neuropathy, which new evidence suggests is much less common than previously suspected.

ESSENTIAL POINTS

Toxic neuropathies can be caused by medications, supplements, and recreational substances that injure peripheral nerves. Medications have evolved in the past 2 decades, as have the types of neuropathies that can be seen as related toxicities. In some areas of medicine, new classes and generations of drugs are associated with a lower incidence of toxic neuropathy.

Crosstalk of Mast Cells and Natural Killer Cells with Neurons in Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a major comorbidity of cancer. Multiple clinical interventions have been studied to effectively treat CIPN, but the results have been disappointing, with no or little efficacy. Hence, understanding the pathophysiology of CIPN is critical to improving the quality of life and clinical outcomes of cancer patients. Although various mechanisms of CIPN have been described in neuropathic anti-cancer agents, the neuroinflammatory process involving cytotoxic/proinflammatory immune cells remains underexamined. While mast cells (MCs) and natural killer (NK) cells are the key innate immune compartments implicated in the pathogenesis of peripheral neuropathy, their role in CIPN has remained under-appreciated. Moreover, the biology of proinflammatory cytokines associated with MCs and NK cells in CIPN is particularly under-evaluated. In this review, we will focus on the interactions between MCs, NK cells, and neuronal structure and their communications via proinflammatory cytokines, including TNFα, IL-1β, and IL-6, in peripheral neuropathy in association with tumor immunology. This review will help lay the foundation to investigate MCs, NK cells, and cytokines to advance future therapeutic strategies for CIPN.

Severe neuromuscular immune-related adverse events of immune checkpoint inhibitors at national cancer center in Korea

PURPOSE

Neuromuscular immune-related adverse events (irAEs) associated with immune checkpoint inhibitors (ICIs) have been increasingly recognized as a consequence of expanding use of ICIs in advanced cancers. We aimed to evaluate the frequency, phenotypes, rescue treatment, and clinical outcomes of severe neuromuscular irAEs of ICIs at National Cancer Center (NCC), Korea.

MATERIALS AND METHODS

Consecutive patients with newly developed severe neuromuscular irAEs (common terminology criteria for adverse events grade 3 or greater) after ICI treatment at NCC in Korea between December 2018 and April 2022 were included by searching neuromuscular diagnostic codes in electronic medical records and/or reviewing neurological consultation documentations.

RESULTS

Of the 1,503 ICI-treated patients, nine (0.6%) experienced severe neuromuscular irAEs; five with pembrolizumab and four with atezolizumab. The patients included five women and four men; their median age at onset was 59 years. The irAEs included Guillain-Barre syndrome (n = 5) and myasthenia gravis (MG) crisis with myositis (n = 4), and developed after a median of one (range 1-5) ICI cycle. The median modified Rankin score (mRS) was 4 (range 3-5) at the nadir. ICIs were discontinued in all patients, and rescue immunotherapy included corticosteroids (n = 9), intravenous immunoglobulin (n = 7), and plasmapheresis (n = 2). Eight patients showed improvements, with a median mRS of 3 (range 1-4); however, one patient (who had MG crisis with myocarditis) died.

CONCLUSIONS

In this real-world monocentric study, ICI-induced neuromuscular irAEs were rare but potentially devastating; thus, physicians should remain vigilant to enable prompt recognition and management of irAEs.

Long-term complete remission after severe pembrolizumab-induced immune-related encephalitis in metastatic lung adeno-squamous carcinoma: A case report

Immune checkpoint inhibitors became the treatment of choice, in monotherapy or in association with platinum-based doublet chemotherapy, in first-line therapy for advanced-stage non-small-cell lung cancer without oncogenic driver. Nevertheless, it can be associated with diverse immune-related adverse events; several immune-related adverse events can also follow each other involving multiple organ systems, leading to immune checkpoint inhibitors discontinuation and immunosuppressive therapy that could compromise the prognosis of patients, with the exception of rare situations such as this clinical case. This case report illustrates a succession of immune-related adverse events including a rare and severe pembrolizumab-induced immune-related encephalitis in a patient with metastatic lung adeno-squamous carcinoma in whom we could observe a long-term and complete remission despite discontinuation of treatment and high-dose corticosteroids. In metastatic non-small-cell lung cancer, a disease with a poor initial prognosis, some patients can benefit from immune checkpoint inhibitors and can even now present a long-term and complete remission and this despite severe and rare immune-related adverse events, high-dose corticosteroids and an early discontinuation of treatment.

Neurological outcomes in immune checkpoint inhibitor-related neurotoxicity

While the spectrum of neurological immune checkpoint inhibitor-related adverse events is expanding, patients' outcomes are not well documented. This study aimed to assess outcomes of neurological immune-related adverse events and to identify prognostic factors. All patients experiencing grade ≥2 neurological immune-related adverse events identified at two clinical networks (French Reference Center for Paraneoplastic Neurological Syndromes, Lyon; and OncoNeuroTox, Paris) over five years were included. Modified Rankin scores were assessed at onset, 6, 12, 18 months, and last visit. A multi-state Markov model was used to estimate the transition rates between minor disability (mRS <3), severe disability (mRS 3-5), and death (mRS 6), over the study period. The state-to-state transition rates were estimated using maximum likelihood and variables were introduced into the different transitions to study their effects. A total of 147 patients were included out of 205 patients with a suspicion of neurological immune-related adverse events. The median age was 65 years (range 20-87) and 87/147 patients (59.2%) were male. Neurological immune-related adverse events involved the peripheral nervous system in 87/147 patients (59.2%), the central nervous system in 51/147 (34.7%), and both systems in 9/147 (6.1%). Paraneoplastic-like syndromes were observed in 30/147 patients (20.4%). Cancers included lung cancers (36.1%), melanoma (30.6%), urological cancers (15.6%), and others (17.8%). Patients were treated with programmed cell death protein (ligan) 1 (PD(L)1) inhibitors (70.1%), CTLA4 inhibitors (3.4%) or both (25.9%). Severe disability was reported in 108/144 patients (75.0%) at onset and in 33/146 patients (22.6%) at last visit (median follow-up duration: 12 months, range 0.5-50); 48/147 (32.7%) patients died, from cancer progression (17/48, 35.4%), neurological toxicity (15/48, 31.2%), other causes (10/48, 20.8%) or unknown causes (6/48, 12.5%). The rate of transition from severe to minor disability independently increased with melanoma [compared to lung cancer, hazard ratio = 3.26, 95%CI (1.27; 8.41)] and myositis/neuromuscular junction disorders [hazard ratio = 8.26, 95%CI (2.90; 23.58)], and decreased with older age [hazard ratio = 0.68, 95%CI (0.47; 0.99)] and paraneoplastic-like syndromes [hazard ratio = 0.29, 95%CI (0.09; 0.98)]. In patients with neurological immune-related adverse events, myositis/neuromuscular junction disorders and melanoma increase the transition rate from severe to minor disability, while older age and paraneoplastic-like syndromes result in poorer neurological outcomes; future studies are needed to optimize the management of such patients.

A Brain, A Heart, and the Courage: Balancing Benefit and Toxicity of Immunotherapy in Melanoma

The overall survival of advanced melanoma has improved dramatically. Immunotherapies, specifically checkpoint inhibitors, have played a large role in this improvement. These agents have also shown benefit in the adjuvant setting, are approved for treatment of resected stage II, III, and IV melanoma, and play an evolving role in the neoadjuvant setting. Although generally well tolerated, immune-related adverse events occur and can be severe. Here we focus on some severe and potentially long term toxicities, including cardiovascular and neurologic toxicities. Our understanding of the acute and long-term toxicities of immune checkpoint inhibitors continues to evolve. Oncologists must continue to balance cancer risk and treatment-related toxicities.

Clinicoserological insights into patients with immune checkpoint inhibitor-induced myasthenia gravis

To compare the immunopathology of immune checkpoint inhibitor-induced myasthenia gravis (ICI-MG) and idiopathic MG, we profiled the respective AChR autoantibody pathogenic properties. Of three ICI-MG patients with AChR autoantibodies, only one showed complement activation and modulation/blocking potency, resembling idiopathic MG. In contrast, AChR autoantibody-mediated effector functions were not detected in the other two patients, questioning the role of their AChR autoantibodies as key mediators of pathology. The contrasting properties of AChR autoantibodies in these cases challenge the accuracy of serological testing in establishing definite ICI-MG diagnoses and underscore the importance of a thorough clinical assessment when evaluating ICI-related adverse events.

Myasthenic crisis

Myasthenic crisis (MC) is a life-threatening manifestation of myasthenia gravis (MG) defined by respiratory insufficiency that requires the use of invasive or non-invasive ventilation. This is often the result of respiratory muscle weakness but can also be due to bulbar weakness with upper airway collapse. MC occurs in approximately 15%-20% of patients with MG usually within the first 2 to 3 y of the disease course. Many crises have a specific trigger with respiratory infections being most common; however, no specific trigger is found in 30%-40% of patients. MG patients with a history of MC, severe disease, oropharyngeal weakness, muscle-specific kinase (MuSK) antibodies and thymoma appear to be at higher risk. Most episodes of MC do not occur suddenly, providing a window of opportunity for prevention. Immediate treatment is directed toward airway management and removing any identified triggers. Plasmapheresis is preferred over intravenous immune globulin as the treatments of choice for MC. The majority of patients are able to be weaned from mechanical ventilation within 1 mo and the outcomes of MC are generally favorable. The mortality rate in United States cohorts is less than 5% and mortality in MC seems to be driven by age and other medical co-morbidities. MC does not appear to affect long-term prognosis as many patients are able to eventually achieve good MG control.

Advances in treatments of patients with classical and emergent neurological toxicities of anticancer agents

The neurotoxicity associated to the anticancer treatments has received a growing body of interest in the recent years. The development of innovating therapies over the last 20years has led to the emergence of new toxicities. Their diagnosis and management can be challenging in the clinical practice and further research is warranted to improve the understanding of their pathogenic mechanisms. Conventional treatments as radiation therapy and chemotherapy are associated to well-known and under exploration emerging central nervous system (CNS) and peripheral nervous system (PNS) toxicities. The identification of the risk factors and a better understanding of their pathogeny through a "bench to bedside and back again" approach, are the first steps towards the development of toxicity mitigation strategies. New imaging techniques and biological explorations are invaluable for their diagnosis. Immunotherapies have changed the cancer treatment paradigm from tumor cell centered to immune modulation towards an efficient anticancer immune response. The use of the immune checkpoints inhibitors (ICI) and chimeric antigen receptor (CAR-T cells) lead to an increase in the incidence of immune-mediated toxicities and new challenges in the neurological patient's management. The neurological ICI-related adverse events (n-irAE) are rare but potentially severe and may present with both CNS and PNS involvement. The most frequent and well characterized, from a clinical and biological standpoint, are the PNS phenotypes: myositis and polyradiculoneuropathy, but the knowledge on CNS phenotypes and their treatments is expanding. The n-irAE management requires a good balance between dampening the autoimmune toxicity without impairing the anticancer immunity. The adoptive cell therapies as CAR-T cells, a promising anticancer strategy, trigger cellular activation and massive production of proinflammatory cytokines inducing frequent and sometime severe toxicity known as cytokine release syndrome and immune effector cell-associated neurologic syndrome. Their management requires a close partnership between oncologist-hematologists, neurologists, and intensivists. The oncological patient's management requires a multidisciplinary clinical team (oncologist, neurologist and paramedical) as well as a research team leading towards a better understanding and a better management of the neurological toxicities.

Septin-3 autoimmunity in patients with paraneoplastic cerebellar ataxia

BACKGROUND

Septins are cytoskeletal proteins with filament forming capabilities, which have multiple roles during cell division, cellular polarization, morphogenesis, and membrane trafficking. Autoantibodies against septin-5 are associated with non-paraneoplastic cerebellar ataxia, and autoantibodies against septin-7 with encephalopathy with prominent neuropsychiatric features. Here, we report on newly identified autoantibodies against septin-3 in patients with paraneoplastic cerebellar ataxia. We also propose a strategy for anti-septin autoantibody determination.

METHODS

Sera from three patients producing similar immunofluorescence staining patterns on cerebellar and hippocampal sections were subjected to immunoprecipitation followed by mass spectrometry. The identified candidate antigens, all of which were septins, were expressed recombinantly in HEK293 cells either individually, as complexes, or combinations missing individual septins, for use in recombinant cell-based indirect immunofluorescence assays (RC-IIFA). Specificity for septin-3 was further confirmed by tissue IIFA neutralization experiments. Finally, tumor tissue sections were analyzed immunohistochemically for septin-3 expression.

RESULTS

Immunoprecipitation with rat cerebellum lysate revealed septin-3, -5, -6, -7, and -11 as candidate target antigens. Sera of all three patients reacted with recombinant cells co-expressing septin-3/5/6/7/11, while none of 149 healthy control sera was similarly reactive. In RC-IIFAs the patient sera recognized only cells expressing septin-3, individually and in complexes. Incubation of patient sera with five different septin combinations, each missing one of the five septins, confirmed the autoantibodies' specificity for septin-3. The tissue IIFA reactivity of patient serum was abolished by pre-incubation with HEK293 cell lysates overexpressing the septin-3/5/6/7/11 complex or septin-3 alone, but not with HEK293 cell lysates overexpressing septin-5 as control. All three patients had cancers (2 × melanoma, 1 × small cell lung cancer), presented with progressive cerebellar syndromes, and responded poorly to immunotherapy. Expression of septin-3 was demonstrated in resected tumor tissue available from one patient.

CONCLUSIONS

Septin-3 is a novel autoantibody target in patients with paraneoplastic cerebellar syndromes. Based on our findings, RC-IIFA with HEK293 cells expressing the septin-3/5/6/7/11 complex may serve as a screening tool to investigate anti-septin autoantibodies in serological samples with a characteristic staining pattern on neuronal tissue sections. Autoantibodies against individual septins can then be confirmed by RC-IIFA expressing single septins.

Dysautonomia associated with immune checkpoint inhibitors

OBJECTIVE

The purpose of this study is to report the clinical characteristics of dysautonomia associated with immune checkpoint inhibitors (ICIs).

METHODS

We reported two patients with autoimmune autonomic ganglionopathy (AAG) occurring as immune-related adverse events (irAEs). We also performed a review of previous case reports presenting dysautonomia during ICI therapy. Moreover, we conducted pharmacovigilance analyses using the US Food and Drug Administration Adverse Events Reporting System (FAERS) to investigate dysautonomia associated with ICI.

RESULTS

Two patients in our care developed both AAG and autoimmune encephalitis following ICI therapy for lung cancers. We comprehensively reviewed 13 published cases (M:F = 11:2, mean onset age of 53 years) with ICI-associated dysautonomia including AAG (n = 3) and autonomic neuropathy (n = 10). Of these, ICI monotherapy was performed in seven and combination ICI use in six. In 6 of 13 patients, dysautonomia appeared within one month after the start of ICIs. Orthostatic hypotension was observed in 7 and urinary incontinence or retention in five. All patients except three showed gastrointestinal symptoms. Anti-ganglionic acetylcholine receptor antibodies were undetectable. All but two patients received immune-modulating therapy. Immuno-modulating therapy was effective in three patients with AAG and two patients with autonomic neuropathy, but ineffective in the others. Five patients died, of either the neurological irAE (n = 3) or cancer (n = 2). The pharmacovigilance analyses using FAERS showed that ipilimumab monotherapy and the combination of nivolumab and ipilimumab constituted significant risks for developing dysautonomia, consistent with the review of literature.

CONCLUSION

ICIs can cause dysautonomia including AAG, and autonomic neuropathy is a neurological irAE.

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.

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.

Peripheral nervous system adverse events associated with immune checkpoint inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICIs) represent an effective cancer immunotherapy yet are associated with immune-related adverse events (irAEs). The aim of this study was to characterize irAEs involving the peripheral nervous system (PNS-irAEs) in a real-world cohort of ICI-treated patients.

METHODS

Cancer patients treated with ICIs between January 2014 and March 2022 were included. Patients with PNS-irAEs were identified and divided into two groups: (1) cranial/peripheral neuropathies and (2) myasthenia gravis (MG) and/or myositis. Clinical characteristics and outcomes, measured with the modified Rankin Scale (mRS), were compared among the two groups.

RESULTS

Among 920 ICI-treated patients, 20 patients (2.17%) developed a PNS-irAEs. The median latency from ICI exposure was 8.8 weeks and the median time from onset to clinical nadir was 3.5 weeks. Eleven patients developed a neuropathy: polyneuropathy (n = 4), cranial neuropathy (n = 3), small-fiber neuropathy (n = 3), brachial plexopathy (n = 1). Nine patients presented MG and/or myositis: concomitant MG and myositis (n = 6), isolated myositis (n = 2), exacerbation of MG (n = 1). Immunosuppressive treatment and/or ICI withdrawal determined a significant clinical improvement, expressed by a mRS reduction, in the neuropathy group (p = 0.004), but not in the MG/myositis group (p = 0.11). Overall, death due to irAEs occurred in four patients (20%), all with MG/myositis. Compared to patients with neuropathies, those with MG/myositis had a shorter latency onset (p = 0.036), developed more frequently concomitant non-neurologic irAEs (p = 0.028) and showed a higher mortality rate (p = 0.026).

CONCLUSIONS

In our large cohort of ICI-treated patients, 2.17% developed PNS-irAEs. Compared to ir-neuropathies, ir-MG/myositis tend to occur earlier from ICI exposure and present a worse response to treatment and a higher mortality.

Monocyte chemoattractant protein 1 as a potential biomarker for immune checkpoint inhibitor-associated neurotoxicity

BACKGROUND

Oncological patients can benefit substantially from treatment with immune checkpoint inhibitors (ICI). However, there is a growing awareness of immune-related adverse events (irAE). Especially ICI-mediated neurological adverse events (nAE(+)), are tough to diagnose and biomarkers to identify patients at risk are missing.

METHODS

A prospective register with prespecified examinations was established for ICI treated patients in December 2019. At the time of data cut-off, 110 patients were enrolled and completed the clinical protocol. Herein, cytokines and serum neurofilament light chain (sNFL) from 21 patients were analyzed.

RESULTS

nAE of any grade were observed in 31% of the patients (n = 34/110). In nAE(+) patients a significant increase in sNFL concentrations over time was observed. Patients with higher-grade nAE had significantly elevated serum-concentrations of monocyte chemoattractant protein 1 (MCP-1) and brain-derived neurotrophic factor (BDNF) at baseline compared to individuals without any nAE (p < 0.01 and p < 0.05).

CONCLUSION

Here, we identified nAE to occur more frequently than previously reported. Increase of sNFL during nAE confirms the clinical diagnosis of neurotoxicity and might be a suitable marker for neuronal damage associated with ICI therapy. Furthermore, MCP-1 and BDNF are potentially the first clinical-class nAE predictors for patients under ICI therapy.

Autoantibody profiles in patients with immune checkpoint inhibitor-induced neurological immune related adverse events

Background

Neurological immune-related adverse events (irAE-n) are severe and potentially fatal toxicities of immune checkpoint inhibitors (ICI). To date, the clinical significance of neuronal autoantibodies in irAE-n is poorly understood. Here, we characterize neuronal autoantibody profiles in patients with irAE-n and compare these with ICI-treated cancer patients without irAE-n.

Methods

In this cohort study (DRKS00012668), we consecutively collected clinical data and serum samples of 29 cancer patients with irAE-n (n = 2 pre-ICI, n = 29 post-ICI) and 44 cancer control patients without irAE-n (n = 44 pre- and post-ICI). Using indirect immunofluorescence and immunoblot assays, serum samples were tested for a large panel of neuromuscular and brain-reactive autoantibodies.

Results

IrAE-n patients and controls received ICI treatment targeting programmed death protein (PD-)1 (61% and 62%), programmed death ligand (PD-L)1 (18% and 33%) or PD-1 and cytotoxic T-lymphocyte-associated protein (CTLA-)4 (21% and 5%). Most common malignancies were melanoma (both 55%) and lung cancer (11% and 14%). IrAE-n affected the peripheral nervous system (59%), the central nervous system (21%), or both (21%). Prevalence of neuromuscular autoantibodies was 63% in irAE-n patients, which was higher compared to ICI-treated cancer patients without irAE-n (7%, p <.0001). Brain-reactive autoantibodies targeting surface (anti-GABA_BR, -NMDAR, -myelin), intracellular (anti-GFAP, -Zic4, -septin complex), or unknown antigens were detected in 13 irAE-n patients (45%). In contrast, only 9 of 44 controls (20%) presented brain-reactive autoantibodies before ICI administration. However, seven controls developed de novo brain-reactive autoantibodies after ICI initiation, therefore, prevalence of brain-reactive autoantibodies was comparable between ICI-treated patients with and without irAE-n (p = .36). While there was no clear association between specific brain-reactive autoantibodies and clinical presentation, presence of at least one of six selected neuromuscular autoantibodies (anti-titin, anti-skeletal muscle, anti-heart muscle, anti-LRP4, anti-RyR, anti-AchR) had a sensitivity of 80% (95% CI 0.52-0.96) and a specificity of 88% (95% CI 0.76-0.95) for the diagnosis of myositis, myocarditis, or myasthenia gravis.

Conclusion

Neuromuscular autoantibodies may serve as a feasible marker to diagnose and potentially predict life-threatening ICI-induced neuromuscular disease. However, brain-reactive autoantibodies are common in both ICI-treated patients with and without irAE-n, hence, their pathogenic significance remains unclear.

Checkpoint inhibitor induced myositis - The value of MRI STIR

•Treatment with immune checkpoint inhibitors can cause serious adverse events.•Myositis combined with myocarditis ad adverse event have a mortality for 50%.•Early diagnosis is important for better outcome.•Employing MRI STIR can rapidly diagnose, guide biopsy, and classify cases of immune-related myositis.

Critical illness-associated weakness and related motor disorders

Weakness of limb and respiratory muscles that occurs in the course of critical illness has become an increasingly common and serious complication of adult and pediatric intensive care unit patients and a cause of prolonged ventilatory support, morbidity, and prolonged hospitalization. Two motor disorders that occur singly or together, namely critical illness polyneuropathy and critical illness myopathy, cause weakness of limb and of breathing muscles, making it difficult to be weaned from ventilatory support, commencing rehabilitation, and extending the length of stay in the intensive care unit, with higher rates of morbidity and mortality. Recovery can take weeks or months and in severe cases, and may be incomplete or absent. Recent findings suggest an improved prognosis of critical illness myopathy compared to polyneuropathy. Prevention and treatment are therefore very important. Its management requires an integrated team approach commencing with neurologic consultation, creatine kinase (CK) measurement, detailed electrodiagnostic, respiratory and neuroimaging studies, and potentially muscle biopsy to elucidate the etiopathogenesis of the weakness in the peripheral and/or central nervous system, for which there may be a variety of causes. These tenets of care are being applied to new cases and survivors of the coronavirus-2 disease pandemic of 2019. This chapter provides an update to the understanding and approach to critical illness motor disorders.

Myasthenia Gravis Induced by Immune Checkpoint Inhibitors: An Emerging Neurotoxicity in Neuro-Oncology Practice: Case Series

Immunotherapy with immune checkpoint inhibitors (ICIs) have been reported to induce de novo or exacerbate pre-existing Myasthenia Gravis (MG). We present a single center case series of patients who developed an immune-related myasthenia gravis (irMG) related with ICIs. We performed a retrospective chart review of the electronic medical records between 1 September 2017 and 2022. We report the clinical features, presentation forms, diagnostic workflows, general management and outcomes of six patients who received ICIs for different solid organ malignancies and developed an irMG frequently overlapping with immune-related myocarditis and/or myositis. The aim of the article is to describe the clinical features, treatment and outcomes of this challenging and potentially life-threating syndrome, comparing our data with those described in the literature. Differences between irMG and classic MG are highlighted.

Acetylcholine receptor binding antibody-associated myasthenia gravis, myocarditis, and rhabdomyolysis induced by tislelizumab in a patient with colon cancer: A case report and literature review

Despite the intriguing therapeutic prospects offered by immune checkpoint inhibitors (ICIs), immune-related adverse events (irAEs) become an increasingly important safety issue. Herein, we report a patient with locally advanced colorectal cancer (LACRC) who received anti-programmed cell death protein 1 (PD-1) (tislelizumab) therapy, then developed weakness of the limbs and drooping eyelids. He experienced sequential irAEs including severe myasthenia gravis, myocarditis, and rhabdomyolysis. Although many irAEs caused by tislelizumab have been reported, the cooccurrence of severe myasthenia gravis, myocarditis, and rhabdomyolysis caused by tislelizumab has not been described. The patient responded well to methylprednisolone and intravenous immunoglobulin therapy. This case illustrates the severe toxicity caused by ICIs, highlighting the importance of early prevention, early diagnosis, and appropriate management of irAEs. Multidisciplinary discussions should be held to improve the prognosis of patients.

Checkpoint Inhibitor Immune-Related Adverse Events: A Multimodality Pictorial Review

Cancer immunotherapies are drugs that modulate the body's own immune system as an anticancer strategy. Checkpoint inhibitor immunotherapies interfere with cell surface binding proteins that function to promote self-recognition and tolerance, ultimately leading to upregulation of the immune response. Given the striking success of these agents in early trials in melanoma and lung cancer, they have now been studied in many types of cancer and have become a pillar of anticancer therapy for many tumor types. However, abundant upregulation results in a new class of side effects, known as immune-related adverse events (IRAEs). It is critical for the practicing radiologist to be able to recognize these events to best contribute to care for patients on checkpoint inhibitor immunotherapy. Here, we provide a comprehensive system-based review of immune-related adverse events and associated imaging findings. Further, we detail the best imaging modalities for each as well as describe problem solving modalities. Given that IRAEs can be subclinical before becoming clinically apparent, radiologists may be the first provider to recognize them, providing an opportunity for early treatment. Awareness of IRAEs and how to best image them will prepare radiologists to make a meaningful contribution to patient care as part of the clinical team.