Risk of Neurological Toxicities Following the Use of Different Immune Checkpoint Inhibitor Regimens in Solid Tumors: A Systematic Review and Meta-analysis

Clinical features, diagnosis, and treatment of pembrolizumab induced autoimmune encephalitis

Pembrolizumab has shown links to autoimmune encephalitis (AE), yet the exact clinical characteristics remain unclear. This study examines the clinical features of pembrolizumab-induced AE to enhance diagnostic accuracy and therapeutic strategies. Reports on pembrolizumab-induced AE were gathered via a searchable database, culminating on November 30, 2024. The median age at onset among the 34 patients was 68 years (range 47-82), with males constituting 67.6%. The average onset period for AE was 6 months (range 0.3-25) after the initial dose, with an average of 6 cycles (range 1-17). Commonly reported symptoms included confusion (38.2%), fever (35.3%), and decreased consciousness (32.4%). Cerebrospinal fluid analysis revealed elevated protein (55.9%), leukocytosis (70.6%), and normal blood glucose levels (38.2%). Antineuronal antibodies were found to be negative in 41.2% of cases and positive in 35.3%. Magnetic resonance imaging indicated T2/FLAIR hypersignal in 32.4% of cases, while the electroencephalogram revealed slow waves (11.8%) and diffuse slowing (11.8%). Following treatment with steroids, intravenous immunoglobulin, and plasmapheresis, 82.4% of patients experienced symptom improvement or recovery, though 5.9% succumbed to AE. Oncologists must consider the risk of AE when prescribing pembrolizumab. Early diagnosis and intervention for AE are crucial. Further research is needed to define the optimal treatment approach.

Autopsy Case of Meningoencephalitis Induced by Nivolumab and Ipilimumab in a Patient Being Treated for Non-small Cell Lung Cancer

A 75-year-old woman with stage IVB (cT2bN3M1b) lung adenocarcinoma was administered nivolumab, ipilimumab, carboplatin, and paclitaxel. Fourteen days after receiving chemotherapy, she experienced an impaired consciousness and a cerebrospinal fluid analysis revealed high protein levels and pleocytosis. She was diagnosed with nivolumab- and ipilimumab-induced encephalitis and was treated with corticosteroids which were tapered to 10 mg/day, with no symptom recurrence. She died 18 weeks after the initial presentation, as the cancer worsened. An autopsy showed encephalitis and CD8+ lymphocyte infiltration around the blood vessels. Thus, immune-related adverse events should be suspected and treatment should be initiated for patients presenting with an impaired consciousness when concurrently being treated with nivolumab and ipilimumab.

Immune checkpoint inhibitors and neurotoxicity: a focus on diagnosis and management for a multidisciplinary approach

INTRODUCTION

Although immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment, the consequential over activation of the immune system is often complicated by adverse events that can affect several organs and systems, including the nervous system. The precise pathophysiology underlying neurological irAEs (n-irAEs) is not completely known. Around 3.8% of patients receiving anti-CTLA-4 agents, 6.1% of patients receiving anti-PD-1/PD-L1, and 12% of patients receiving combination therapies have n-irAEs. Most n-irAEs are low-grade, while severe toxicities have rarely been reported. in this article, we performed an updated literature search on immuno-related neurotoxicity on main medical research database, from February 2017 to December 2023.

AREAS COVERED

We have also compared the latest national and international guidelines on n-irAEs management with each other in order to better define patient management.

EXPERT OPINION

A multidisciplinary approach appears necessary in the management of oncological patients during immunotherapy. Therefore, in order to better manage these toxicities, we believe that it is essential to collaborate with neurologists specialized in the diagnosis and treatment of n-irAEs, and that a global neurological assessment, both central and peripheral, is necessary before starting immunotherapy, with regular reassessment during treatment.

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.

Autoimmune encephalitis following treatment with durvalumab for small-cell lung cancer

The traditional treatment for small-cell lung cancer (SCLC) has been traditional systemic platinum-containing chemotherapy because the response rate is 50-90%. Durvalumab is an immune checkpoint inhibitor that blocks the binding of programmed cell death protein 1 and programmed cell death 1 ligand 1. Durvalumab combined with traditional chemotherapy agents has been recommended as the first-line treatment for extensive-stage SCLC, but its use may cause immune-related adverse events. Autoimmune encephalitis is a rare and potentially fatal neurological adverse event. This current case report describes a male patient in his late 50s with ES-SCLC who developed autoimmune encephalitis associated with durvalumab treatment after three cycles of combination chemotherapy. This current case furthers the understanding of autoimmune encephalitis caused by durvalumab treatment.

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.

Rare Immune-Related Adverse Events (irAEs): Approach to Diagnosis and Management

Immune checkpoint inhibitors (ICIs) have revolutionised the treatment landscape across many solid organ malignancies and form part of routine clinical practice in many tumours. As indications for monotherapy, doublet therapy and combination approaches with chemotherapy and targeted agents expand, clinicians must be aware of the wide range of possible immune-related adverse events (irAEs). Common toxicities, including rash, colitis, hepatitis and pneumonitis are well described in the literature, and have established diagnostic and management algorithms. Rarer toxicities, often with an incidence of less than 1%, are less defined. These syndromes can be poorly recognised, may take on a fulminant course and do not have established or evidence-based diagnostic and management strategies. As such, patients may experience increased morbidity, mortality and poorer outcomes, related both to these irAEs as well as how the treatment of these may affect the management of their underlying malignancy. In this review, we aim to explore the incidence, potential biomarkers, pathogenesis, diagnostic work-up and clinical sequelae of a selection of uncommon irAEs, with a focus on myocarditis, neurological and haematologic syndromes. Further prospective research is required to accurately define the incidence and pathogenesis of these conditions, with the aim of increasing clinician awareness of rare irAEs and to assist with a more personalised and mechanism-based approach to these syndromes.

Exploring a Rarity: Incidence of and Therapeutic Approaches for Neurological Complications and Hypophysitis in Cancer Patients on Immune Checkpoint Inhibitors-A Single-Center Study

Immune checkpoint inhibitors, such as anti-PD-1 and anti-CTLA-4 inhibitors, have become the standard of care for many cancer types. However, they induce immune-related adverse events (irAEs), including neurotoxicity and hypophysitis. The incidence and outcomes of neurotoxicity and hypophysitis in patients treated with immune checkpoint inhibitors are not well established. We conducted a retrospective study of 812 patients with solid cancers who received immune checkpoint inhibitors at the University General Hospital of Ioannina between January 2018 and January 2023. We assessed demographic and clinical data, including the severity of symptoms, treatment regimen, other irAEs, resolution type and time, and death. Two patients experienced neurotoxicity and two hypophysitis. All four patients required inpatient administration and received corticosteroids or/and hormone replacement. Three patients responded to the initial therapy, experiencing full recovery, while one patient was corticosteroid-resistant, and immunoglobin G was administered. Two patients never received immunotherapy after their toxicity due to the severity of symptoms; one patient continued monotherapy with nivolumab, changing from combination therapy with ipilimumab-nivolumab, while the fourth patient continued his initial treatment with nivolumab. Our study suggests that the incidence of neurotoxicity and hypophysitis in patients treated with immune checkpoint inhibitors is low, but careful monitoring and prompt treatment with corticosteroids are necessary for effective management.

Toxicities associated with immune checkpoint inhibitors: a systematic study

BACKGROUND

Available evidence shows that the incidence of toxicities associated with cancer immunotherapy, such as programmed cell death 1 (PD-1) and programmed cell death 1 ligand 1 (PD-L1)-related toxicities, is estimated to be between 0.3 and 1.3%.

OBJECTIVE

This systematic review aimed to investigate cancer patients' susceptibility to toxicities associated with PD-1/PD-L1 inhibitors and establish a clinically relevant landscape of side effects of PD-1/PD-L1 inhibitors.

DATA SOURCES

Relevant publications from PubMed, Embase, Cochrane Library, Web of Science, and China National Knowledge Infrastructure (CNKI) between 2014 and 2019.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTIONS

We searched randomized controlled trials (RCTs) reporting treatment-related toxicities associated with PD-1 and PD-L1 inhibitors in the treatment of cancers. The primary endpoint was to assess the difference in the incidences of toxicities between cancer patients who did and did not receive PD-1/PD-L1 inhibitors. A total of 29 RCTs, incorporating 8576 patients, met the eligibility criteria.

STUDY APPRAISAL AND SYNTHESIS METHODS

We calculated the pooled relative risks and corresponding 95% CIs using a random-effects model and assessed the heterogeneity between different groups. The subgroup analyses were conducted based on cancer type, toxicity grade (severity), system and organ, treatment regimens in the intervention arm and the control arm, PD-1/PD-L1 inhibitor drug type, and cancer type.

RESULTS

A total of 11 categories (e.g. endocrine toxicity), and 39 toxicity types (e.g. hyperthyroidism) were identified. For toxicities at any grade, those treated with PD-1/PD-L1 inhibitors were at lower risks for gastrointestinal toxicity, hematologic toxicity, and treatment event leading to discontinuation; and were at higher risks for respiratory toxicity (all P <0.05). Those treated with PD-1/PD-L1 inhibitors were at lower risks for fatigue, asthenia, and peripheral edema and were at higher risks for pyrexia, cough, dyspnea, pneumonitis, and pruritus.

LIMITATIONS

The present research is a meta-analysis at the study level rather than at the patient level; insights on risk factors associated with the development of toxicities cannot be found in our study. There was a possible overlap in Common Terminology Criteria for Adverse Events (CTCAE) definitions which prevents understanding the true rates of specific toxicities.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

For most toxicity types based on system and organ, the incidence proportions for patients in the intervention arm were lower than those in the control arm, which suggested the general safety of PD-1/PD-L1 inhibitors against conventional chemotherapy and cytotoxic t-lymphocyte-associated protein 4 (CTLA-4) inhibitors. Future research should focus on taking effective targeted measures to decrease the risks of different toxicities for different patient populations.

SYSTEMATIC REVIEW REGISTRATION NUMBER

We registered the research protocol with PROSPERO (registration number CRD42019135113).

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.

Implication of the Gut Microbiome and Microbial-Derived Metabolites in Immune-Related Adverse Events: Emergence of Novel Biomarkers for Cancer Immunotherapy

Immune checkpoint inhibitors (ICIs) have changed how we think about tumor management. Combinations of anti-programmed death ligand-1 (PD-L1) immunotherapy have become the standard of care in many advanced-stage cancers, including as a first-line therapy. Aside from improved anti-tumor immunity, the mechanism of action of immune checkpoint inhibitors (ICIs) exposes a new toxicity profile known as immune-related adverse effects (irAEs). This novel toxicity can damage any organ, but the skin, digestive and endocrine systems are the most frequently afflicted. Most ICI-attributed toxicity symptoms are mild, but some are severe and necessitate multidisciplinary side effect management. Obtaining knowledge on the various forms of immune-related toxicities and swiftly changing treatment techniques to lower the probability of experiencing severe irAEs has become a priority in oncological care. In recent years, there has been a growing understanding of an intriguing link between the gut microbiome and ICI outcomes. Multiple studies have demonstrated a connection between microbial metagenomic and metatranscriptomic patterns and ICI efficacy in malignant melanoma, lung and colorectal cancer. The immunomodulatory effect of the gut microbiome can have a real effect on the biological background of irAEs as well. Furthermore, specific microbial signatures and metabolites might be associated with the onset and severity of toxicity symptoms. By identifying these biological factors, novel biomarkers can be used in clinical practice to predict and manage potential irAEs. This comprehensive review aims to summarize the clinical aspects and biological background of ICI-related irAEs and their potential association with the gut microbiome and metabolome. We aim to explore the current state of knowledge on the most important and reliable irAE-related biomarkers of microbial origin and discuss the intriguing connection between ICI efficacy and toxicity.

Neurology of cancer immunotherapy

BACKGROUND

Immunotherapy is nowadays considered a mainstay of cancer treatment, dramatically affecting the disease-free survival rate in several aggressive malignancies. Unfortunately, cancer immunotherapy can also trigger life-threatening autoimmune neurological complications named "neurological adverse effects" (NAEs). NAEs can affect both the central nervous system (CNS), as in ipilimumab-related aseptic meningitis, and the peripheral nervous system (PNS), as in nivolumab-induced myasthenia gravis.

CURRENT EVIDENCE

The incidence of NAEs is highly variable, ranging from 2 to 4% using checkpoint inhibitors to 50% using blinatumomab. Looking at these numbers, it appears clear that neurologists will soon be called more and more frequently to decide upon the best therapeutic strategy for a patient receiving immunotherapy and experiencing a NAE. Most of them can be treated or reverted withholding the offending drug and adding IVIg, plasmapheresis, or steroids to the therapy. Sometimes, however, for oncological reasons, immunotherapy cannot be stopped so the neurologist needs to know what countermeasures have proven most effective. Moreover, patients with a pre-existing autoimmune neurological disease (AID), such as myasthenia gravis or multiple sclerosis, might need immunotherapy during their life, risking a severe worsening of their symptoms. In that setting, the neurologist needs to properly counsel patients about the risk of a therapy-related relapse.

CONCLUSION

In this article, we describe the most frequently reported NAEs and aim to give neurologists a practical overview on how to deal with them.

Environmental Risks for Inflammatory Myopathies

This is an up-to-date review on external environmental factors for adult-onset idiopathic inflammatory myopathies (IIMs). Environmental factors with suggestive evidence including ultraviolet radiation, smoking, infectious agents (viruses in particular), pollutants, medications (ie, statin) and vitamin D deficiency are discussed. We also discuss the potential implications of environmental factors in IIM development, identify current challenges, and provide insight into future investigations.

Severe Immune-Related Adverse Events: A Case Series of Patients Needing Hospital Admission in a Spanish Oncology Referral Center and Review of the Literature

Immune checkpoint inhibitors (ICI) have revolutionized the landscape of cancer treatment. Although several studies have shown that ICIs have a better safety profile than chemotherapy, some patients develop immune-related adverse events (irAEs), which require specialized and multidisciplinary management. Since ICI indications are rapidly increasing, it is crucial that clinicians involved in cancer care learn to identify irAEs and manage them properly. Here, we report a case series of 23 patients with severe irAEs requiring hospitalization over a period of 12 months and seize the opportunity to review and update different general features related to irAEs along with the management of the most frequent severe irAEs in our series.

Immune Checkpoint Inhibitor Associated Autoimmune Encephalitis, Rare and Novel Topic of Neuroimmunology: A Case Report and Review of the Literature

Immune checkpoint inhibitors (ICIs) are being used in patients with various advanced malignancies, and patient outcomes have improved considerably. Although ICIs can effectively treat tumors, 30-60% of patients experience immune-related adverse events (irAEs). Autoimmune encephalitis (AE) is a rare irAE that has become a novel topic in neuroimmunology and has received increasing attention in recent years. Herein, we report a rare case of GAD65-antibody-associated AE after metastatic small cell lung cancer treatment with pembrolizumab. The patient received IVIg therapy for AE and continuous pembrolizumab therapy without suspension of tumor treatment. At 1 year follow-up, both the patient's AE symptoms and tumors were stable. We consider that the treatment of ICI-associated AE should be more individualized with prudent decision-making and should balance the tumor progression and AE treatment. In addition, we have also comprehensively reviewed the literature of ICI-associated AE, and summarized the clinical features, treatment, and prognosis of AE caused by ICI, thus broadening our understanding of the neurological complications caused by ICI.

Adverse Events Associated with Immune Checkpoint Inhibitors: Overview of Systematic Reviews

BACKGROUND

Recognition and management of adverse events (AEs) associated with immune checkpoint inhibitor (ICI) use by cancer patients requires expertise from multiple disciplines. Greater awareness of potential AEs may result in earlier recognition, appropriate management, and better patient outcomes.

OBJECTIVE

The primary objective of this overview of systematic reviews was to synthesize and consolidate systematic review evidence describing the incidence proportion and severity of AEs associated with various ICI therapies across different cancers.

METHODS

A systematic literature search of four databases was conducted to identify systematic reviews that describe the incidence proportion and severity of AEs related to ICI therapy in cancer patients. A systematic review was eligible if it included adults with cancer; on ICI alone or in combination with another ICI, chemotherapy, or targeted therapy; severity (graded according to the Common Terminology Criteria for Adverse Events) and incidence proportion of AEs and whether it reported its eligibility criteria. AEs of interest were identified through an iterative ranking exercise by key stakeholders and knowledge users. Extraction of PICOTTS elements and quality indicators (AMSTAR-2) were used to manage overlap of primary studies across systematic reviews at the outcome level. Cancer subtypes were mapped to drug class and AE severity.

RESULTS

Overall, 129 systematic reviews met the inclusion criteria for data mapping. Systematic reviews reported incidence proportions for more than 76 AEs, of which 34 were identified as AEs of interest. After overlap assessment, 65 systematic reviews were chosen for data extraction. The three AEs with the highest median incidence were fatigue (18.3%, interquartile range [IQR] 15.0-28.0%), diarrhea (15.3%, IQR 9.7-29.2%) and rash (14.4%, IQR 10.3-19.2%). The three AEs (high-grade) with the highest median incidence were diarrhea (1.5%, IQR 1.2-6.0%), colitis (1.3%, IQR 0.6-6.1%) and neutropenia (1.2%, IQR 0.4-3.3%). Incidence proportions of high-grade AEs were often considerably lower than all-grade AEs and combination therapy (ICI combinations or combinations of ICI with chemotherapy or targeted therapy) was responsible for some of the highest incidence proportions regardless of AE. Rare AEs and certain cancer subtypes were not well reported.

CONCLUSIONS

Early recognition of AEs associated with ICIs requires expertise from diverse specialists, not just oncologists. Greater awareness of potential AEs may result in earlier recognition, appropriate management, and better patient outcomes.

PROSPERO REGISTRATION

CRD42021231593.

Neurologic Toxicity of Immune Checkpoint Inhibitors: A Review of Literature

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

Management of Immune-Related Adverse Events in Patients Treated With Immune Checkpoint Inhibitor Therapy: ASCO Guideline Update

PURPOSE

To increase awareness, outline strategies, and offer guidance on the recommended management of immune-related adverse events (irAEs) in patients treated with immune checkpoint inhibitor (ICPi) therapy.

METHODS

A multidisciplinary panel of medical oncology, dermatology, gastroenterology, rheumatology, pulmonology, endocrinology, neurology, hematology, emergency medicine, nursing, trialists, and advocacy experts was convened to update the guideline. Guideline development involved a systematic literature review and an informal consensus process. The systematic review focused on evidence published from 2017 through 2021.

RESULTS

A total of 175 studies met the eligibility criteria of the systematic review and were pertinent to the development of the recommendations. Because of the paucity of high-quality evidence, recommendations are based on expert consensus.

RECOMMENDATIONS

Recommendations for specific organ system-based toxicity diagnosis and management are presented. While management varies according to the organ system affected, in general, ICPi therapy should be continued with close monitoring for grade 1 toxicities, except for some neurologic, hematologic, and cardiac toxicities. ICPi therapy may be suspended for most grade 2 toxicities, with consideration of resuming when symptoms revert ≤ grade 1. Corticosteroids may be administered. Grade 3 toxicities generally warrant suspension of ICPis and the initiation of high-dose corticosteroids. Corticosteroids should be tapered over the course of at least 4-6 weeks. Some refractory cases may require other immunosuppressive therapy. In general, permanent discontinuation of ICPis is recommended with grade 4 toxicities, except for endocrinopathies that have been controlled by hormone replacement. Additional information is available at www.asco.org/supportive-care-guidelines.

Encephalitis Induced by Immune Checkpoint Inhibitors: A Systematic Review

Importance

Encephalitis is a severe immune-related adverse event secondary to treatment with immune checkpoint inhibitors (ICIs). The spectrum of ICI-induced encephalitis (ICI-iE) ranges from disease that resolves fully to lethal forms. Moreover, ICIs may unmask a paraneoplastic encephalitis. To our knowledge, the factors associated with ICI-iE prognosis are unknown.

Objectives

To evaluate the presentation of ICI-iE and to identify features helpful in assessing outcomes.

Evidence Review

This systematic review pooled case series from the published literature (n = 77) and medical records from 1 center (n = 5) to assess the association between the form of ICI-iE presentation and its prognosis. Eligibility criteria included references identified by searches of PubMed and Web of Knowledge databases in the English literature from June 2000 (first patient dose of ipilimumab) to April 17, 2020, that examined patients with encephalitis with presumed autoimmune etiologic features induced by ICIs. Information regarding clinical, cerebrospinal fluid, and neuroimaging (magnetic resonance imaging) features, as well as treatment given, were extracted.

Findings

A total of 82 patients (52 men [63%]; median age, 61.0 years [interquartile range, 52.5-70.0 years]) were included. Most patients presented with focal syndromes (39 [48%]) or meningoencephalitis (36 [44%]). Seven patients (9%) had nonclassifiable ICI-iE. Neuronal autoantibodies were detected in 23 patients with focal syndromes and 1 patient with nonclassifiable ICI-iE. Most autoantibodies were onconeuronal (17 of 24 [71%]), targeting intracellular antigens. Patients without a focal syndrome or with a negative-antibody focal syndrome had a good prognosis (49 of 55 [89%]). Among patients with autoantibodies, those with anti-glutamic acid decarboxylase or anticell surface responded to treatment and had a favorable prognosis (100%). However, patients with other autoantibodies had poor outcomes (17 of 24 [71%]). Antineuronal autoantibodies (13 of 24 [54%] vs 5 of 41 [12%]; P < .001), focal syndrome (16 of 39 [41%] vs 4 of 43 [9%]; P = .001), and abnormal magnetic resonance imaging findings (14 of 39 [36%] vs 4 of 32 [13%]; P = .02) were associated with poor outcomes. Conversely, fever (21 of 23 [91%] vs 41 of 59 [70%]; P = .04) and more inflammatory changes in cerebrospinal fluid (30 of 31 [97%] vs 21 of 33 [64%]; P = .001) were associated with a better prognosis.

Conclusions and Relevance

Immune checkpoint inhibitors may induce mainly 2 different encephalitic syndromes: a focal limbic or extralimbic encephalitis and a meningoencephalitis. Immune checkpoint inhibitor-induced encephalitis is associated with an overall favorable outcome, with a low rate of fatal events. An undetected preexisting paraneoplastic encephalitic syndrome may be triggered by ICIs, and this type of syndrome has the worst outcome among all the different types of ICI-induced encephalitis syndromes. Clinical presentation and systematic measurement of autoantibodies will be a helpful guide for the therapeutic strategy and for counseling regarding prognosis.

Consensus disease definitions for neurologic immune-related adverse events of immune checkpoint inhibitors

Expanding the US Food and Drug Administration-approved indications for immune checkpoint inhibitors in patients with cancer has resulted in therapeutic success and immune-related adverse events (irAEs). Neurologic irAEs (irAE-Ns) have an incidence of 1%-12% and a high fatality rate relative to other irAEs. Lack of standardized disease definitions and accurate phenotyping leads to syndrome misclassification and impedes development of evidence-based treatments and translational research. The objective of this study was to develop consensus guidance for an approach to irAE-Ns including disease definitions and severity grading. A working group of four neurologists drafted irAE-N consensus guidance and definitions, which were reviewed by the multidisciplinary Neuro irAE Disease Definition Panel including oncologists and irAE experts. A modified Delphi consensus process was used, with two rounds of anonymous ratings by panelists and two meetings to discuss areas of controversy. Panelists rated content for usability, appropriateness and accuracy on 9-point scales in electronic surveys and provided free text comments. Aggregated survey responses were incorporated into revised definitions. Consensus was based on numeric ratings using the RAND/University of California Los Angeles (UCLA) Appropriateness Method with prespecified definitions. 27 panelists from 15 academic medical centers voted on a total of 53 rating scales (6 general guidance, 24 central and 18 peripheral nervous system disease definition components, 3 severity criteria and 2 clinical trial adjudication statements); of these, 77% (41/53) received first round consensus. After revisions, all items received second round consensus. Consensus definitions were achieved for seven core disorders: irMeningitis, irEncephalitis, irDemyelinating disease, irVasculitis, irNeuropathy, irNeuromuscular junction disorders and irMyopathy. For each disorder, six descriptors of diagnostic components are used: disease subtype, diagnostic certainty, severity, autoantibody association, exacerbation of pre-existing disease or de novo presentation, and presence or absence of concurrent irAE(s). These disease definitions standardize irAE-N classification. Diagnostic certainty is not always directly linked to certainty to treat as an irAE-N (ie, one might treat events in the probable or possible category). Given consensus on accuracy and usability from a representative panel group, we anticipate that the definitions will be used broadly across clinical and research settings.

Neuromuscular complications of cancer therapy

PURPOSE OF THE REVIEW

The neuromuscular complications of cancer therapy include chemotherapy-induced peripheral neurotoxicity (CIPN), immune-related neuromuscular complications to immune checkpoint inhibitors and radiation-induced neuropathy/plexopathy. With a wider focus on CIPN, we will discuss new pathogenetic insights, recent predictive biomarkers and emerging therapies for neuromuscular complications of cancer therapy.

RECENT FINDINGS

Findings from recent preclinical studies have improved our knowledge on new CIPN pathogenetic pathways, including the activation of senescence-like processes in neurons, axonal degeneration and neuroinflammation. Metabolomics and serum neurofilament light chain levels appear the most promising biomarkers to predict CIPN development and severity. There is some recent evidence of promising pharmacological compounds to prevent or treat CIPN, and new drugs are in early development and testing.

SUMMARY

A multimodal assessment, with neurophysiological, imaging and patient-reported outcome measures, coupled with the use of reliable blood or genetic biomarkers, may offer pathogenetic grounds for future preventive and symptomatic strategies for the multidisciplinary treatment of neuromuscular complications of cancer therapy.

Critically ill patients with severe immune checkpoint inhibitor related neurotoxicity: A multi-center case series

PURPOSE

Serious immune checkpoint inhibitor (ICI)-related neurotoxicity is rare. There is limited data on the specifics of care and outcomes of patients with severe neurological immune related adverse events (NirAEs) admitted to the Intensive Care Unit (ICU).

MATERIALS AND METHODS

Retrospective study of patients with severe NirAEs admitted to the ICU at 3 academic centers between January 2016 and December 2018. Clinical data collected included ICI exposure, type of NirAE (central [CNS] or peripheral nervous system [PNS) disorders), and patient outcomes including neurological recovery and mortality.

RESULTS

Seventeen patients developed severe NirAEs. Eight patients presented with PNS disorders; 6 with myasthenia gravis (MG), 1 had a combination of MG and polyneuropathy and 1 had Guillain-Barre syndrome. Nine patients had CNS disorders (6 seizures and 5 had concomitant encephalopathy. During ICU admission, 65% of patients required mechanical ventilation, 35% vasopressors, and 18% renal replacement therapy. The median ICU and hospital length of stay were 7 (2-36) and 18 (4-80) days, respectively. Hospital mortality was 29%. At hospital discharge, 18% of patients made a full neurologic recovery, 41% partial recovery, and 12% did not recover.

CONCLUSION

Severe NirAEs while uncommon, can be serious or even life-threatening if not diagnosed and treated early.

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.

Immune Checkpoint Inhibitors and Neurotoxicity

Immune checkpoint inhibitors (ICIs) have recently been used as a promising treatment for cancer, while their toxicity and immune-related side effects can be seen in any organ, including the nervous system. In contrast to other immune-related adverse events (irAEs), neurological irAEs (nAEs) are rare, with varying incidence and symptom complexity. Although nAEs are uncommon, they can sometimes be severe and even lead to death. However, little attention has been paid to nAEs, and the literature is mostly clinical reports with only a few cases. We, therefore, conducted the present review with the aim of providing a comprehensive introduction of nAEs. In this review, we summarized various nAEs, including meningitis, encephalitis, and hypophysitis in the central nervous system, and myositis, myasthenia gravis, and peripheral neuropathies in the peripheral system. We also reviewed the current diagnosis and treatment methods for nAEs commonly used in clinical practice. In addition, we discussed potential mechanisms regarding nAEs and proposed the possible approaches to prevent the risk of nAEs in patients treated with ICIs. There is still a lot to learn, such as whether and why patients with nAEs respond better to ICI-therapy. The mechanisms and significance of nAEs need to be fully clarified to address these issues and optimize the treatment strategy.

International Consensus Guidance for Management of Myasthenia Gravis: 2020 Update

Objective

To update the 2016 formal consensus-based guidance for the management of myasthenia gravis (MG) based on the latest evidence in the literature.

Methods

In October 2013, the Myasthenia Gravis Foundation of America appointed a Task Force to develop treatment guidance for MG, and a panel of 15 international experts was convened. The RAND/UCLA appropriateness method was used to develop consensus recommendations pertaining to 7 treatment topics. In February 2019, the international panel was reconvened with the addition of one member to represent South America. All previous recommendations were reviewed for currency, and new consensus recommendations were developed on topics that required inclusion or updates based on the recent literature. Up to 3 rounds of anonymous e-mail votes were used to reach consensus, with modifications to recommendations between rounds based on the panel input. A simple majority vote (80% of panel members voting “yes”) was used to approve minor changes in grammar and syntax to improve clarity.

Results

The previous recommendations for thymectomy were updated. New recommendations were developed for the use of rituximab, eculizumab, and methotrexate as well as for the following topics: early immunosuppression in ocular MG and MG associated with immune checkpoint inhibitor treatment.

Conclusion

This updated formal consensus guidance of international MG experts, based on new evidence, provides recommendations to clinicians caring for patients with MG worldwide.

Immune-Driven Pathogenesis of Neurotoxicity after Exposure of Cancer Patients to Immune Checkpoint Inhibitors

Over the last decade, immune checkpoint inhibitors (ICIs) have revolutionized the treatment of several cancer types. ICIs work through the blockage of immune inhibitory signals, while increasing the T-cell specific immune antitumoral response. However, due to the fact that ICIs’ mechanism of action is not tissue antigen-specific and not limited to the tumor microenvironment, the use of cancer immunotherapy can produce a broad range of immune-related adverse events (irAEs). Neurological immune-related adverse events (NirAEs) are rare (the overall incidence varies between 1% to 6%), and these adverse events mainly concern the peripheral nervous system, rather than the central nervous system. Due to their potential severity, which could cause interruptions to cancer treatment, NirAEs are of particular clinical importance. Currently, the pathogenesis of these complications is not completely understood, although T-cells seem to play a principal role. Nevertheless, the development of NirAEs is likely to be a multifactorial and complex process. This conclusion can be extracted from the wide range of neurological auto-inflammatory and autoimmune disorders triggered or exacerbated by ICIs, and the extensive variability of the limited histological findings reported. The aim of this review is to summarize the potential immune-driven pathological mechanisms of NirAEs.

Immune Checkpoint Inhibitor-Related Myositis: From Biology to Bedside

Immune checkpoint inhibitor (ICI)-related inflammatory diseases, including polymyositis (PM) and dermatomyositis (DM), in patients suffering from neoplastic disorders represent a medical challenge. The treatment of these conditions has taken on new urgency due to the successful and broad development of cancer-directed immunological-based therapeutic strategies. While primary and secondary PM/DM phenotypes have been pathophysiologically characterized, a rational, stepwise approach to the treatment of patients with ICI-related disease is lacking. In the absence of high-quality evidence to guide clinical judgment, the available data must be critically assessed. In this literature review, we examine partially neglected immunological and clinical findings to obtain insights into the biological profiles of ICI-related PM/DM and potential treatment options. We show that differential diagnosis is essential to stratifying patients according to prognosis and therapeutic impact. Finally, we provide a comprehensive assessment of druggable targets and suggest a stepwise patient-oriented approach for the treatment of ICI-related PM/DM.

Immune checkpoint inhibitors-induced neuromuscular toxicity: From pathogenesis to treatment

Immune checkpoint inhibitors (ICIs) are increasingly used and are becoming the standard of care in the treatment of various tumor types. Despite the favorable results in terms of oncological outcomes, these treatments have been associated with a variety of immune-related adverse events (irAEs). Neurological irAEs are rare but potentially severe. Neuromuscular disorders represent the most common neurological irAEs following anti-PD-1, anti-PD-L1, and anti-CTLA-4 treatment, and include myositis, myasthenia gravis, and demyelinating polyradiculoneuropathy. Instrumental findings may differ from typical neuromuscular disorders occurring outside ICIs treatment. Despite initial severity, neurological irAEs often respond to immune-modulating therapies. Prompt irAEs diagnosis, ICIs discontinuation, and early treatment with corticosteroids, together with patient education and a multi-disciplinary approach, are important for optimizing clinical outcomes. Intravenous immunoglobulin, plasma exchange, and other immune-modulating treatments should be considered in more severe cases. Consideration of re-challenging with the same immunotherapy drug may be given in some cases, based on clinical picture and initial severity of irAEs.

Incidence and characteristics of neurotoxicity in immune checkpoint inhibitors with focus on neuromuscular events: Experience beyond the clinical trials

Immune checkpoint inhibitors (ICIs) are associated with various neurological adverse events (NAEs). We herein explored the incidence and clinical phenotype of immune-related NAEs in cancer patients. Medical records of ICI-treated cancer patients were reviewed between the years 2010 and 2018, with an aim to characterize immuno-related NAEs. A total of 1185 ICIs-treated patients were identified, 63.7% of which were males and 36.3% were females, with a mean age of 63.4 ± 7.3 years. Twenty-four from the overall ICIs-treated patients (2%) developed NAEs. No differences were identified in terms of age, sex, tumor type and class of ICIs between the patients who developed NAEs and those who did not. The median number of cycles of ICI treatment before NAEs onset were 4.5 (1-10), and the median time was 102 days. Peripheral nervous system (PNS) involvement was present in 14 patients (58.4%) and central nervous system (CNS) involvement in 10 (33.3%), including 2 patients with aseptic meningitis and polyradicular involvement. Amongst PNS complications, there were five (20.8%) with axonal sensory neuropathies, four (16.7%) with Guillain-Barre-like syndromes, and four (16.7%) with myositis and/or myasthenic syndromes. The majority of patients with PNS-related NAEs (n = 11; 78.6%) improved after ICIs discontinuation and treatment with immune-modulating therapies. The time to neuromuscular toxicities onset was significantly shorter, compared to CNS NAEs (median 70 vs 119 days, P = .037). Immune-related NAEs mostly present with neuromuscular complications. Discontinuation of ICIs and appropriate treatment should be commenced early throughout the process, in order to maximize a favorable outcome.