Central nervous system complications associated with immune checkpoint inhibitors

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.

Neurological autoimmunity in patients with non-pulmonary neuroendocrine neoplasms: clinical manifestations and neural autoantibody profiles

BACKGROUND AND PURPOSE

Paraneoplastic neurological autoimmunity is well described with small-cell lung cancer, but information is limited for other neuroendocrine neoplasms (NENs).

METHODS

Adult patients with histopathologically confirmed non-pulmonary NENs, neurological autoimmunity within 5 years of NEN diagnosis, and neural antibody testing performed at the Mayo Clinic Neuroimmunology Laboratory (January 2008 to March 2023) were retrospectively identified. Control sera were available from patients with NENs without neurological autoimmunity (116).

RESULTS

Thirty-four patients were identified (median age 68 years, range 31-87). The most common primary tumor sites were pancreas (nine), skin (Merkel cell, eight), small bowel/duodenum (seven), and unknown (seven). Five patients received immune checkpoint inhibitor (ICI) therapy before symptom onset; symptoms preceded cancer diagnosis in 62.1% of non-ICI-treated patients. The most frequent neurological phenotypes (non-ICI-treated) were movement disorders (12; cerebellar ataxia in 10), dysautonomia (six), peripheral neuropathy (eight), encephalitis (four), and neuromuscular junction disorders (four). Neural antibodies were detected in 55.9% of patients studied (most common specificities: P/Q-type voltage-gated calcium channel [seven], muscle-type acetylcholine receptor [three], anti-neuronal nuclear antibody type 1 [three], and neuronal intermediate filaments [two]), but in only 6.9% of controls. Amongst patients receiving cancer or immunosuppressive therapy, 51.6% had partial or complete recovery. Outcomes were unfavorable in 48.3% (non-ICI-treated) and neural autoantibody positivity was associated with poor neurological outcome.

DISCUSSION

Neurological autoimmunity associated with non-pulmonary NENs is often multifocal and can be treatment responsive, underscoring the importance of rapid recognition and early treatment.

Cerebral clues: serum neurofilament light chain (sNfL) as a novel biomarker for immune check point inhibitor (ICI) mediated seronegative encephalitis

Immune checkpoint inhibitor (ICI) mediated encephalitides are increasingly being recognized in the literature, but atypical cases may be missed or misdiagnosed. Recent efforts are directed to identify biomarkers to help elucidate early diagnosis and treatment. Herein, we describe two cases of antibody negative ICI-mediated encephalitis with elevated serum Neurofilament light chain (sNfL) levels. Practical Implication: Baseline and longitudinal measurements of serum neurofilament light chains can help determine treatment strategies and prognosis in patients with suspected immune checkpoint inhibitor encephalitis.

Autoimmune Movement Disorders Complicating Treatment with Immune Checkpoint Inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICI) may trigger autoimmune neurological conditions, including movement disorders (MD).

OBJECTIVES

The aim of this study was to characterize MDs occurring as immune-related adverse events (irAEs) of ICIs.

METHODS

A systematic literature review of case reports/series of MDs as irAEs of ICIs was performed.

RESULTS

Of 5682 eligible papers, 26 articles with 28 patients were included. MDs occur as a rare complication of cancer immunotherapy with heterogeneous clinical presentations and in most cases in association with other irAEs. Inflammatory basal ganglia T2/fluid attenuated inversion recovery abnormalities are rarely observed, but brain imaging is frequently unrevealing. Cerebrospinal fluid findings are frequently suggestive of inflammation. Half of cases are associated with a wide range of autoantibodies. Steroids and ICI withdrawal usually lead to improvement, even though some patients experienced relapses or a severe clinical course.

CONCLUSION

MDs are a rare complication of ICIs that should be promptly recognized to offer patients a correct diagnosis and treatment.

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.

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.

Paraneoplastic neurologic syndrome associated with gynecologic and breast malignancies

Gynecologic and breast malignancies are the cancers most commonly associated with paraneoplastic neurologic syndromes, of which the foremost is Yo [Purkinje cell antibody, type 1 (PCA-1)] paraneoplastic cerebellar degeneration. Yo syndrome affects women in the sixth decade and manifests as a subacute severe cerebellar ataxia. The association of the typical clinical picture with the detection of Yo antibodies in a patient's serum or CSF defines the diagnosis. Yo syndrome is always associated with a cancer, and the search for the underlying tumor should focus on ovarian and breast cancers and be repeated overtime if negative. The Yo autoantibodies are directed against the Yo antigens, aberrantly overexpressed by tumor cells with frequent somatic mutations and gene amplifications. The massive infiltration of these tumors by immune cells suggests that they are the site of the immune tolerance breakdown, leading to the destruction of Purkinje cells harboring the Yo antigens. Despite a growing understanding of the immunologic mechanisms, efficient therapeutic options are still lacking. Anti-Ri and antiamphiphysin syndromes are rarer and associated with breast cancers; a wide variety of other rare paraneoplastic neurologic syndromes have been described in association with gynecologic and breast malignancies that, though sharing some similarities, may have specific immune and genetics features leading to the immune tolerance breakdown.

Clinical Impact of Pre-Existing Autoantibodies in Patients With SCLC Treated With Immune Checkpoint Inhibitor: A Multicenter Prospective Observational Study

Introduction

Although pretreatment autoantibodies have been associated with immune-related adverse events (irAEs) and immune checkpoint inhibitor treatment efficacy in some types of cancer, their importance has not been evaluated in patients with SCLC.

Methods

A multicenter prospective observational study was conducted on a total of 52 patients with extensive-disease SCLC who received immune checkpoint inhibitors in combination with chemotherapy as the first-line treatment at either of the six participating centers in Japan. Pretreatment serum samples were collected and analyzed for autoantibodies (rheumatoid factor, antinuclear antibodies, and antithyroid). Moreover, 12 antineuronal antibodies (AMPH, CV2, PNMA2, Ri, Yo, Hu, Recoverin, SOX1, Titin, Zic4, GAD65, and Tr) were analyzed using immunoblot assays. The primary end point was the incidence of irAEs with or without autoantibodies. The secondary end points were progression-free survival (PFS) and overall survival (OS) on the basis of the presence or absence of autoantibodies.

Results

PFS and OS were 4.4 and 25.3 months, respectively. Autoantibodies (rheumatoid factor, antinuclear antibodies, and antithyroid antibodies) were detected in 29 patients (56%). In total, irAEs were observed in 18 patients (35%); irAE incidence was 48% in the autoantibody-positive group and 17% in the autoantibody-negative group (p = 0.039). There was no difference in PFS or OS between patients with and without autoantibodies (4.4 mo versus 4.6 mo, p = 0.36; 15.3 mo versus 18.2 mo, p = 0.36). Antineuronal antibodies were detected in 16 patients (31%). However, the development of neurologic irAEs was not observed in both groups.

Conclusions

Vigilance is required against the development of irAEs in pretreatment antibody-positive patients.

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.

Paraneoplastic encephalitis: clinically based approach on diagnosis and management

Paraneoplastic neurological syndromes (PNSs) comprise a subset of immune-mediated nervous system diseases triggered by an underlying malignancy. Each syndrome usually shows a distinct clinical presentation and outcome according to the associated neural antibodies. PNSs generally have a subacute onset with rapid progression and severe neurological disability. However, some patients may have hyperacute onset or even show chronic progression mimicking neurodegenerative diseases. Updated diagnostic criteria for PNS have been recently established in order to increase diagnostic specificity and to encourage standardisation of research initiatives related to PNS. Treatment for PNS includes oncological therapy and immunomodulation to halt neurological deterioration although current treatment options are seldom effective in reversing disability. Nevertheless, growing knowledge and better understanding of PNS pathogenesis promise better recognition, earlier diagnosis and novel treatment strategies. Considering that PNSs provide a model of effective anticancer immunity, the impact of these studies will extend far beyond the field of neurology.

Neurologic Complications of Cancer Immunotherapy

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

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.

Paraneoplastic Neurological Syndromes of the Central Nervous System: Pathophysiology, Diagnosis, and Treatment

Paraneoplastic neurological syndromes (PNS) include any symptomatic and non-metastatic neurological manifestations associated with a neoplasm. PNS associated with antibodies against intracellular antigens, known as "high-risk" antibodies, show frequent association with underlying cancer. PNS associated with antibodies against neural surface antigens, known as "intermediate- or low-risk" antibodies, are less frequently associated with cancer. In this narrative review, we will focus on PNS of the central nervous system (CNS). Clinicians should have a high index of suspicion with acute/subacute encephalopathies to achieve a prompt diagnosis and treatment. PNS of the CNS exhibit a range of overlapping "high-risk" clinical syndromes, including but not limited to latent and overt rapidly progressive cerebellar syndrome, opsoclonus-myoclonus-ataxia syndrome, paraneoplastic (and limbic) encephalitis/encephalomyelitis, and stiff-person spectrum disorders. Some of these phenotypes may also arise from recent anti-cancer treatments, namely immune-checkpoint inhibitors and CAR T-cell therapies, as a consequence of boosting of the immune system against cancer cells. Here, we highlight the clinical features of PNS of the CNS, their associated tumors and antibodies, and the diagnostic and therapeutic strategies. The potential and the advance of this review consists on a broad description on how the field of PNS of the CNS is constantly expanding with newly discovered antibodies and syndromes. Standardized diagnostic criteria and disease biomarkers are fundamental to quickly recognize PNS to allow prompt treatment initiation, thus improving the long-term outcome of these conditions.

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.

Targeting programmed cell death protein 1 (PD-1) for treatment of non-small-cell lung carcinoma (NSCLC); the recent advances

The immune system uses various immune checkpoint axes to adjust responses, support homeostasis, and deter self-reactivity and autoimmunity. Nevertheless, non-small-cell lung carcinoma (NSCLC) can use protective mechanisms to facilitate immune evasion, which leads to potentiated cancer survival and proliferation. In this light, many blocking anti-bodies have been developed to negatively regulate checkpoint molecules, in particular, programmed cell death protein 1 (PD-1) / PD-ligand 1 (L1), and bypass these immune suppressive mechanisms. Meanwhile, anti-PD-1 anti-bodies such as nivolumab, pembrolizumab, cemiplimab, and sintilimab have shown excellent competence in successfully inspiring immune responses versus NSCLC. Accordingly, the United States Food and Drug Administration (FDA) has recently approved nivolumab (alone or in combination with ipilimumab) and pembrolizumab (alone or in combination with chemotherapy) as first-line treatment for advanced NSCLC patients. However, PD-1 blockade monotherapy remains inefficient in more than 60% of NSCLC patients, and many patients don't respond or acquire resistance to this modality. Also, toxicities related to anti-PD-1 anti-body have been progressively identified in clinical trials and oncology practice. Herein, we will outline the clinical benefits of PD-1 blockade therapy alone or in combination with other treatments (e.g., chemotherapy, radiotherapy, anti-angiogenic therapy) in NSCLC patients. Moreover, we will take a glimpse into the recently identified predictive biomarkers to determine patients most likely to suffer serious adverse events to decrease untoward toxicity risk and diminish treatment costs.

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.

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.

Cerebellar involvement associated with immune checkpoint inhibitors: A systematic review

BACKGROUND AND PURPOSE

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

METHODS

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

RESULTS

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

DISCUSSION

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

Origins and immunopathogenesis of autoimmune central nervous system disorders

The field of autoimmune neurology is rapidly evolving, and recent discoveries have advanced our understanding of disease aetiologies. In this article, we review the key pathogenic mechanisms underlying the development of CNS autoimmunity. First, we review non-modifiable risk factors, such as age, sex and ethnicity, as well as genetic factors such as monogenic variants, common variants in vulnerability genes and emerging HLA associations. Second, we highlight how interactions between environmental factors and epigenetics can modify disease onset and severity. Third, we review possible disease mechanisms underlying triggers that are associated with the loss of immune tolerance with consequent recognition of self-antigens; these triggers include infections, tumours and immune-checkpoint inhibitor therapies. Fourth, we outline how advances in our understanding of the anatomy of lymphatic drainage and neuroimmune interfaces are challenging long-held notions of CNS immune privilege, with direct relevance to CNS autoimmunity, and how disruption of B cell and T cell tolerance and the passage of immune cells between the peripheral and intrathecal compartments have key roles in initiating disease activity. Last, we consider novel therapeutic approaches based on our knowledge of the immunopathogenesis of autoimmune CNS disorders.

Seizures, Epilepsy, and NORSE Secondary to Autoimmune Encephalitis: A Practical Guide for Clinicians

The most recent International League Against Epilepsy (ILAE) classification has included "immune etiology" along with other well-known causes of epilepsy. This was possible thanks to the progress in detection of pathogenic neural antibodies (Abs) in a subset of patients, and resulted in an increased interest in identifying potentially treatable causes of otherwise refractory seizures. Most autoimmune encephalitides (AE) present with seizures, but only a minority of cases evolve to long-term epilepsy. The risk of epilepsy is higher for patients harboring Abs targeting intracellular antigens (T cell-mediated and mostly paraneoplastic, such as Hu, CV2/CRMP5, Ma2, GAD65 Abs), compared with patients with neuronal surface Abs (antibody-mediated and less frequently paraneoplastic, such as NMDAR, GABAbR, LGI1, CASPR2 Abs). To consider these aspects, conceptual definitions for two entities were provided: acute symptomatic seizures secondary to AE, and autoimmune-associated epilepsy, which reflect the different pathophysiology and prognoses. Through this manuscript, we provide an up-to-date review on the current state of knowledge concerning diagnosis and management of patients with Ab-mediated encephalitis and associated epilepsy. Special emphasis is placed on clinical aspects, such as brain magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) specificities, electroencephalographic (EEG) findings, cancer screening and suggestions for a rational therapeutic approach.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Novelties in Autoimmune and Paraneoplastic Cerebellar Ataxias: Twenty Years of Progresses

Major advances in our knowledge concerning autoimmune and paraneoplastic cerebellar ataxias have occurred in the last 20 years. The discovery of several neural antibodies represents an undeniable contribution to this field, especially those serving as good biomarkers of paraneoplastic neurological syndromes and those showing direct pathogenic effects. Yet, many patients still lack detectable or known antibodies, and also many antibodies have only been reported in few patients, which makes it difficult to define in detail their clinical value. Nevertheless, a notable progress has additionally been made in the clinical characterization of patients with the main neural antibodies, which, although typically present with a subacute pancerebellar syndrome, may also show either hyperacute or chronic onsets that complicate the differential diagnoses. However, prodromal and transient features could be useful clues for an early recognition, and extracerebellar involvement may also be highly indicative of the associated antibody. Moreover, important advances in our understanding of the pathogenesis of cerebellar ataxias include the description of antibody effects, especially those targeting cell-surface antigens, and first attempts to isolate antigen-specific T-cells. Furthermore, genetic predisposition seems relevant, although differently involved according to cancer association, with particular HLA observed in non-paraneoplastic cases and genetic abnormalities in the tumor cells in paraneoplastic ones. Finally, immune checkpoint inhibitors used as cancer immunotherapy may rarely induce cerebellar ataxias, but even this undesirable effect may in turn serve to shed some light on their physiopathology. Herein, we review the principal novelties of the last 20 years regarding autoimmune and paraneoplastic cerebellar ataxias.

Atezolizumab‑associated encephalitis in metastatic breast cancer: A case report

Immune checkpoint inhibitors have been critical in the treatment of advanced malignancies in recent years. Encephalitis caused by atezolizumab is an uncommon immune-related adverse event. The case of a 65-year-old female diagnosed with encephalitis closely associated with atezolizumab medication for metastatic advanced breast cancer is presented in the current study. Following a fourth atezolizumab dose 10 days previously, the patient fell into a deep coma. Initial brain magnetic resonance imaging revealed multiple patchy T2 hyperintensities in the bilateral cerebellar hemisphere, vermis of the cerebellum, bilateral frontal lobe, temporal lobe, parietal lobe and occipital cortex. Meanwhile, there were aberrant signs on diffusion-weighted imaging. The diagnosis of atezolizumab-induced encephalitis seemed probable after ruling out other possible causes of encephalitis. Subsequently, the condition of the patient worsened and there were indications of cardiac and respiratory arrest. Chest compressions were provided immediately, as well as a balloon mask for assisted ventilation, a medication boost, stimulated breathing and other symptomatic therapy. The patient's vital signs temporarily stabilised after this series of rescue measures. The patient refused further therapy and insisted on being discharged, and died a few days after being discharged from the hospital. In this case, the patient's encephalitis symptoms associated with atezolizumab were not as typical as previously documented. The patient's condition swiftly deteriorated to heartbeat apnea, and steroid pulse therapy was not received in a timely manner, resulting in an unfavourable outcome.

Autoantibody Encephalitis: Presentation, Diagnosis, and Management

Autoantibody encephalitis causes distinct clinical syndromes involving alterations in mentation, abnormal movements, seizures, psychiatric symptoms, sleep disruption, spasms, and neuromyotonia. The diagnoses can be confirmed by specific antibody tests, although some antibodies may be better detected in spinal fluid and others in serum. Each disorder conveys a risk of certain tumors which may inform diagnosis and be important for treatment. Autoantibodies to receptors and other neuronal membrane proteins are generally thought to be pathogenic and result in loss of function of the targets, so understanding the pharmacology of the receptors may inform our understanding of the syndromes. Patients may be profoundly ill but the syndromes usually respond to immune therapy, although there are differences in the types of immune therapy that are thought to be most effective for the various disorders.

Recognizing New-Onset Sleep Disorders in Autoimmune Encephalitis Often Prompt Earlier Diagnosis

SUMMARY

Sleep/wake disorders are common in patients with autoimmune encephalitis, sometimes the most prominent or sole initial symptom, then delaying diagnosis. Sleep/wake disorders in autoimmune encephalitis vary and include severe sleeplessness, hypersomnia, central and/or obstructive sleep apnea, rapid eye movement sleep behavior disorder, indeterminate sleep/wake states, and loss of circadian sleep/wake rhythms. N-methyl- d aspartate receptor encephalitis (NMDAR) is often associated with insomnia, then hypersomnia and sleep-related central hypoventilation. Profound sleeplessness and rapid eye movement sleep behavior disorder are seen in patients with voltage-gated potassium channel-complex antibodies. Fragmented sleep and hypersomnia are common in paraneoplastic syndromes associated with anti-MA protein encephalitis; rapid eye movement sleep behavior disorder in those with antibodies against leucine-rich glioma inactivated protein (LGI1) or contactin-associated protein 2 (CASPR2) antibodies. Antibodies against a cell adhesion protein IGLON5 may result in obstructive sleep apnea, inspiratory stridor, disorganized nonrapid eye movement sleep, and excessive movements and parasomnias fragmenting nonrapid and rapid eye movement sleep. Recognizing a particular sleep/wake disorder is often a presenting or prominent feature in certain autoimmune encephalitis permit for earlier diagnosis. This is important because reduced morbidity and better short- and long-term outcomes are associated with earlier diagnosis and immunotherapies.

Paraneoplastic Neurological Syndromes: Transitioning Between the Old and the New

PURPOSE OF REVIEW

Paraneoplastic neurological syndromes (PNS) are caused by nervous system-targeting aberrant anti-tumoral immune responses. We review the updated criteria for PNS diagnosis, incorporating novel information on clinical phenotypes, neuronal autoantibodies (Nabs), and tumors. The impact of the oncologic use of immune checkpoint inhibitors (ICI) on PNS occurrence is also addressed.

RECENT FINDINGS

Clinical phenotypes and Nabs are redefined as "high/intermediate/low" risk, following the frequency of cancer association. Nabs, the diagnostic hallmark of PNS, can target intracellular or surface neuronal proteins, with important prognostic and pathogenic implications. Many novel assays have been incorporated into laboratory diagnostics, that is becoming increasingly complex. ICI fight tumors, but favor autoimmunity, thus increasing the incidence of PNS-like disorders. Overcoming the old PNS criteria, the new ones are centered around the presence of tumor. Clinical presentation, Nabs, and tumor findings are translated in diagnostic scores, providing a useful tool for PNS diagnosis and management.

Paraneoplastic Autoimmune Neurological Syndromes and the Role of Immune Checkpoint Inhibitors

The introduction of immune checkpoint inhibitors (ICIs) in oncologic therapies has led to a paradigm shift in cancer treatment. ICIs have increased the overall survival in patients with malignant melanoma, small-cell lung cancer, and many other tumor entities. Despite their clinical benefits, these novel cancer immunotherapies can induce neurological immune-related adverse events (irAEs). Such immune-mediated complications can manifest within the spectrum of paraneoplastic neurological syndromes (PNSs). PNSs are rare immune-mediated complications of systemic cancers that can involve every aspect of the nervous system. The emergence of PNSs with ICI treatment opens further pathways to study the complex immunopathological interplay of cancer immunity, cross-reactive neurological autoimmune phenomena, and effects of ICIs on the immune system. ICI-induced PNSs comprise a diverse antibody repertoire and phenotypic spectrum with severe and life-threatening disease progression in some cases. Timely diagnosis and urgent interventions are pivotal for a favorable neurologic and oncologic outcome. This review focuses on the pathogenesis of cancer immunotherapy and the disruption of immune tolerance in PNSs and provides an overview of the most pertinent clinical manifestations and principles of diagnostic and therapeutic managements in light of the expected increase in PNSs due to the widespread use of ICIs in clinical practice. This review further discusses potential and evolving concepts of therapeutic monoclonal antibodies for the treatment of PNSs.

PARANEOPLASTIC SYNDROMES REVIEW: THE GREAT FORGOTTEN ONES

Paraneoplastic syndromes (PNS) are a group of disorders that can affect the oncologic patient, and which are not directly attributable to tumour invasion, tumour compression or metastasis. In fact, they are due to tumour secretion of functional hormones or peptides or are related to immune cross-reactivity with the host tissue. These syndromes are called paraneoplastic because the components that cause them do not derive from the organ or tissue of origin, but from the neoplasm suffered by the patient. It is estimated that 10-15% of people with cancer suffer from a PNS.(1) PNS is the second direct cause of death (27% of cases) in cancer patients, after cancer itself. Consequently, it is of remarkable importance to recognize and treat SPNs specifically.(2) In view of the above, the aim of this article is to review the state of the art in neurological, haematological, endocrine, and dermatological paraneoplastic syndromes. It is a review in which the most relevant PNS and their symptomatology are described, inquiring into their diagnosis and treatment.

Peripheral neuropathy and headache in cancer patients treated with immunotherapy and immuno-oncology combinations: the MOUSEION-02 study

INTRODUCTION

Treatment-related neurotoxicity is a common side effect in cancer patients. However, few data are available regarding the risk of several neurotoxicities in patients treated with immune checkpoint inhibitors.

AREAS COVERED

The MOUSEION-02 study is an up-to-date meta-analysis aimed at assessing the risk of peripheral neuropathy, peripheral sensory neuropathy, and headache in cancer patients receiving immunotherapy and immuno-oncology combinations. Patients receiving immunotherapy (as monotherapy or in combination with other anticancer agents) showed lower risk of all-grade peripheral neuropathy (RR, 0.50; 95% CI, 0.35-0.70) and all-grade peripheral sensory neuropathy (RR, 0.49; 95% CI, 0.30-0.79). Similarly, in patients treated with immune checkpoint inhibitor monotherapy, we observed lower risk of all-grade peripheral neuropathy (RR, 0.05; 95% CI, 0.03-0.10) and all-grade peripheral sensory neuropathy (RR, 0.11; 95% CI, 0.05-0.23). No differences were observed in terms of all-grade headache.

EXPERT OPINION

Although the results of this meta-analysis should be interpreted with caution due to several issues, our study draws attention to immunotherapy-related neurotoxicity with the aim of maximizing clinical outcomes of cancer patients experiencing these not uncommon, and yet poorly studied, adverse events.

Neurologic Complications of Immune Checkpoint Inhibitors

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

Paraneoplastic Opsoclonus-myoclonus Syndrome with Anti-Hu and Anti-SOX-1 Antibodies after Immune-checkpoint Inhibitor Treatment Combined with Chemotherapy in a Patient with Small-cell Lung Cancer

A 69-year-old man with advanced small-cell lung cancer achieved partial remission after 3 courses of immunochemotherapy that included atezolizumab. Ten days after the last treatment, he developed paraneoplastic opsoclonus-myoclonus syndrome and required mechanical ventilation. Serology testing detected anti-Hu and anti-SOX-1 antibodies. Despite steroid pulse therapy, various anticonvulsants, continuous intravenous sedation, and a fourth course of chemotherapy without atezolizumab, his condition failed to improve. Paraneoplastic opsoclonus-myoclonus syndrome with autoantibodies after immune-checkpoint inhibitor treatment has not been reported previously. Although a causal relationship between immune-checkpoint inhibitors and paraneoplastic syndromes has been suggested, the mechanism remains unknown.

Anti-Ma2-Associated Limbic Encephalitis after Termination of Immune Checkpoint Inhibitor Therapy for Malignant Pleural Mesothelioma

Neurological adverse events of immune checkpoint inhibitor (ICI) therapy mostly develop within 3 months after initiation of ICI treatment. An 82-year-old male with malignant pleural mesothelioma developed anti-Ma2-associated limbic encephalitis at a delay of 18 months after the start of nivolumab therapy (3 months after termination of a 15-month course of ICI treatment). Immunotherapy with steroids and immunoglobulins resulted in moderate neurological improvement. Over the next year, malignant pleural mesothelioma gradually worsened, while the anti-Ma2 antibody test remained positive. Anti-Ma2 paraneoplastic encephalitis may occur after a delay following the discontinuation of ICI therapy.

Autoantibodies in neurological disease

The realization that autoantibodies can contribute to dysfunction of the brain has brought about a paradigm shift in neurological diseases over the past decade, offering up important novel diagnostic and therapeutic opportunities. Detection of specific autoantibodies to neuronal or glial targets has resulted in a better understanding of central nervous system autoimmunity and in the reclassification of some diseases previously thought to result from infectious, 'idiopathic' or psychogenic causes. The most prominent examples, such as aquaporin 4 autoantibodies in neuromyelitis optica or NMDAR autoantibodies in encephalitis, have stimulated an entire field of clinical and experimental studies on disease mechanisms and immunological abnormalities. Also, these findings inspired the search for additional autoantibodies, which has been very successful to date and has not yet reached its peak. This Review summarizes this rapid development at a point in time where preclinical studies have started delivering fundamental new data for mechanistic understanding, where new technologies are being introduced into this field, and - most importantly - where the first specifically tailored immunotherapeutic approaches are emerging.

[Neurological symptoms associated with cancer treatment]

Die onkologische Behandlung ist biomarkerbasierter, molekular maßgeschneiderter und effektiver geworden. Aufbauend auf der zunehmenden Entschlüsselung zellbiologischer und molekularer Mechanismen steigt auch die Zahl zielgerichteter medikamentöser Therapien. Es steigt zudem die Zahl der Langzeitüberlebenden. Eine neuro(onko)logische Betreuung wird immer wichtiger, nicht nur wegen vermehrter direkter tumorbedingter Symptome – wie etwa der höheren Inzidenz einer Metastasierung in das Zentralnervensystem –, sondern weil im Zuge dieser modernen onkologischen systemischen Therapieformen ein breites Spektrum therapieassoziierter neurologischer Symptome auftritt, die einer sorgfältigen und raschen neurologischen/neuroonkologischen Evaluation und Therapiekonzeption bedürfen. Das Ziel dieses Artikels ist es, das Bewusstsein für die häufigsten therapieassoziierten neurologischen Symptome zu schärfen.

Anti-γ-Aminobutyric Acid Type β Receptor Antibody-Associated Encephalitis After 2 Cycles of Durvalumab Therapy in a Patient with Small Cell Lung Cancer: A Case Report

Anti-γ-aminobutyric acid type β receptor (anti-GABA_BR) antibody-associated encephalitis is a type of autoimmune encephalitis. According to current literature, its pathogenesis is reported to be closely related to tumor factors. However, diagnosis can be difficult because of the rarity of cases, limited clinical understanding, and a lack of specificity in clinical manifestation and imaging presentation. Clinical trials have demonstrated that immunotherapy can prolong the survival of patients with small cell lung cancer; however, in some cases, immunotherapy may induce anti-GABA_BR antibody-associated encephalitis. Patients who develop this encephalitis during immunotherapy often delay treatment because the cause is not clearly identified. In this study, we report a case of a 61-year-old man with a confirmed diagnosis of small cell lung cancer who had acute onset of cognitive impairment and seizures after two cycles of durvalumab (AstraZeneca UK Limited) combination chemotherapy. This reaction was initially considered as an immune-related adverse event (irAE) caused by durvalumab treatment, and the patient was eventually considered to have a paraneoplastic neurological disorder caused by the primary tumor. This report raises awareness of the symptoms of cognitive impairment and seizures in patients with small cell lung cancer, and the possible adverse events associated with immunotherapy. This case also highlights the importance of detecting anti-GABA_BR antibodies in patients with small cell lung cancer.

[A case of meningoencephalitis and polyradiculoneuropathy induced by combination therapy with ipilimumab and nivolumab]

A 76-year-old man with renal cell carcinoma exhibited consciousness disturbance and high fever after two cycles of combination therapy with ipilimumab and nivolumab. His cerebrospinal fluid (CSF) showed a protein concentration of 385 mg/dl, a cell count of 147/mm³, an interleukin-6 concentration of 1,280 pg/ml, and an adenosine deaminase concentration of 24.8 U/l. Contrast-enhanced FLAIR images were notable for diffuse meningeal enhancement. He was diagnosed with meningoencephalitis caused by an immune-related adverse event from immune checkpoint inhibitors (ICIs). His symptoms improved after repeated intravenous methylprednisolone pulse therapy and oral prednisolone. The meningeal enhancement disappeared, and the CSF findings became almost normal. As consciousness levels improved, we observed quadriplegia and peripheral neuropathy with antiganglioside antibodies, which led to a diagnosis of polyradiculoneuropathy. This is a rare case of a patient with overlapping meningoencephalitis and polyradiculo-neuropathy induced by ICIs.