HLA-B27 association of autoimmune encephalitis induced by PD-L1 inhibitor

Soluble biomarkers for immune checkpoint inhibitor-related encephalitis: A mini-review

Immune checkpoint inhibitors lead to effective antitumour responses but also to immune-related adverse events (irAEs), which affect the nervous system in 1-5% of patients. Encephalitis is the most frequent central nervous system irAE and is clinically relevant due to its high severity and mortality. Early diagnosis is crucial but is hampered by the broad list of alternative diagnoses, the lack of established diagnostic criteria, and the need of extensive diagnostic procedures (e.g., spinal tap, brain MRI) alongside expert neurological evaluation. Additionally, the response to corticosteroids is inconsistent, and the management of corticosteroid-refractory patients remains poorly defined. This mini-review discusses the role of various soluble biomarkers in the diagnosis, prognostication, and management of ICI-encephalitis. Neural antibodies, which are well-established biomarkers of autoimmune and paraneoplastic encephalitis, are found in only a subset of ICI-encephalitis, in which they can aid to establish the diagnosis. The most prevalent are paraneoplastic neurological syndromes (PNS)-associated antibodies, which are found almost exclusively in focal ICI-encephalitis syndromes and are associated with poor outcomes, possibly due to predominantly cytotoxic T cell involvement leading to irreversible neuronal loss. Beside antibodies, serum brain injury biomarkers such as NfL and S100B are elevated in ICI-encephalitis and, even if non-specific, may be useful as a routine test to quickly identify patients in whom neurological evaluation and second-level diagnostic procedures should be prioritized. Additionally, higher serum and CSF NfL levels have been associated with lack of treatment response in ICI-encephalitis, suggesting they may have a prognostic role. Among cytokines, elevated interleukin 6 (IL6) levels have been observed in serum and/or CSF samples of some patients with ICI-encephalitis, but the role of IL6 as a biomarker for response to IL6-directed therapies requires further investigation. Likewise, the value of other biomarkers, including T cells markers and HLA haplotypes, still needs to be evaluated in large cohorts. Overall, neural antibodies are important diagnostic and prognostic biomarkers in ICI-encephalitis, and other soluble biomarkers, especially NfL, deserve further investigation since they have a promising application in clinical practice.

Association of human leucocyte antigen loci with vaccine-induced immune thrombotic thrombocytopenia: Potential role of the interaction between platelet factor 4-derived peptides and MHC-II

No risk factors have been identified for vaccine-induced immune thrombotic thrombocytopenia (VITT) so far. The aim of this study was to identify human leucocyte antigen (HLA) alleles potentially associated with VITT susceptibility. Specific HLA class II alleles were detected with significantly higher frequency in VITT patients compared with Italian controls: DPB1*17:01, DQA1*05:01, and DRB1*11:04. In silico analysis revealed increased affinity of DRB1*11:04 for a platelet factor 4 (PF4)-derived peptide, ITSLEVIKA, that contains two amino acids present in the specific binding site of anti-PF4 antibodies from VITT patients. Our findings show for the first time a genetic predisposition to developing anti-PF4 antibodies in response to Ad-vector vaccines.

Biomarkers associated with immune-related adverse events induced by immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) constitute a pivotal class of immunotherapeutic drugs in cancer treatment. However, their widespread clinical application has led to a notable surge in immune-related adverse events (irAEs), significantly affecting the efficacy and survival rates of patients undergoing ICI therapy. While conventional hematological and imaging tests are adept at detecting organ-specific toxicities, distinguishing adverse reactions from those induced by viruses, bacteria, or immune diseases remains a formidable challenge. Consequently, there exists an urgent imperative for reliable biomarkers capable of accurately predicting or diagnosing irAEs. Thus, a thorough review of existing studies on irAEs biomarkers is indispensable. Our review commences by providing a succinct overview of major irAEs, followed by a comprehensive summary of irAEs biomarkers across various dimensions. Furthermore, we delve into innovative methodologies such as machine learning, single-cell RNA sequencing, multiomics analysis, and gut microbiota profiling to identify novel, robust biomarkers that can facilitate precise irAEs diagnosis or prediction. Lastly, this review furnishes a concise exposition of irAEs mechanisms to augment understanding of irAEs prediction, diagnosis, and treatment strategies.

Neurological Immune-Related Adverse Events Induced by Immune Checkpoint Inhibitors

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

Biomarkers for immune-related adverse events in cancer patients treated with immune checkpoint inhibitors

Although immune checkpoint inhibitors have greatly improved cancer therapy, they also cause immune-related adverse events, including a wide range of inflammatory side effects resulting from excessive immune activation. Types of immune-related adverse events are diverse and can occur in almost any organ, with different frequencies and severities. Furthermore, immune-related adverse events may occur within the first few weeks after treatment or even several months after treatment discontinuation. Predictive biomarkers include blood cell counts and cell surface markers, serum proteins, autoantibodies, cytokines/chemokines, germline genetic variations and gene expression profiles, human leukocyte antigen genotype, microRNAs and the gut microbiome. Given the inconsistencies in research results and limited practical utility, there is to date no established biomarker that can be used in routine clinical practice, and additional investigations are essential to demonstrate efficacy and subsequently facilitate integration into routine clinical use.

Exploration of Germline Correlates and Risk of Immune-Related Adverse Events in Advanced Cancer Patients Treated with Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) are increasingly used in the treatment of many tumor types, and durable responses can be observed in select populations. However, patients may exhibit significant immune-related adverse events (irAEs) that may lead to morbidity. There is limited information on whether the presence of specific germline mutations may highlight those at elevated risk of irAEs. We evaluated 117 patients with metastatic solid tumors or hematologic malignancies who underwent genomic analysis through the ongoing Personalized OncoGenomics (POG) program at BC Cancer and received an ICI during their treatment history. Charts were reviewed for irAEs. Whole genome sequencing of a fresh biopsy and matched normal specimens (blood) was performed at the time of POG enrollment. Notably, we found that MHC class I alleles in the HLA-B27 family, which have been previously associated with autoimmune conditions, were associated with grade 3 hepatitis and pneumonitis (q = 0.007) in patients treated with combination PD-1/PD-L1 and CTLA-4 inhibitors, and PD-1 inhibitors in combination with IDO-1 inhibitors. These data highlight that some patients may have a genetic predisposition to developing irAEs.

HLA inherence as a potential parameter in checkpoint inhibitor-associated autoimmune adverse event assessment

Background

The success of immunotherapy has made it a lifesaving treatment, but not without side effects. Currently, the risk factors for developing immune-related adverse events (irAEs) in patients who receive immunotherapy are poorly understood, and there is no risk-stratifying mechanism for potentially fatal irAEs. It is postulated that oncology patients with preexisting autoimmune diseases are likely to have flares on immunotherapy. However, some patients develop de novo autoimmune conditions on immunotherapy without a prior history. Literature reports have postulated that human leukocyte antigen (HLA) inherence may play a role in irAEs. However, this potential remains underexplored.

Methods

The oncology patients who developed autoimmune adverse events on immunotherapy for whom the continuation of treatment was prudent or lifesaving were selected. Of note, all nine patients received checkpoint inhibitors (CIs). Of the nine selected patients, only one had a prior history of an autoimmune condition. None of the nine selected patients had an active autoimmune condition at the time of CI initiation. Their HLA was typed, and the results were cross-referenced with the literature reports in PubMed and Google search with the corresponding autoimmune condition of each patient.

Results

Herein, we report nine patients with irAEs for whom retrospective HLA typing revealed the inherence of multiple related HLA alleles that may correspond to the autoimmune condition that they had developed on immunotherapy. It is to be mentioned that the inherence of enriched disease-related HLA alleles was shared among patients with the same irAEs. These patients developed a range of irAEs including bullous pemphigoid, pemphigus foliaceus/vulgaris, thyroiditis, vitiligo, and hepatitis on immunotherapy. Although some combinations of disease-related HLA were well reported in otherwise idiopathic autoimmune diseases, a frequently repeated HLA allele combination in our patient population was found to be rarely seen in the general population.

Conclusion

The authors suggest that an enriched inherence of disease-related HLA alleles may play a role in the genetic propensity for the development of irAEs in oncology patients, who receive immunotherapy, including CIs. Inherence of more than one or a cluster of particular autoimmune disease-related HLA alleles in patients who receive immunotherapy may unmask the corresponding autoimmune disease as the genotype inherence presents with the phenotype of the corresponding condition. It is suggested that enriched linked HLA genotypes, which are otherwise rare in the general population, may present as the corresponding phenotype of the autoimmune condition. Such clinical presentation, enhanced by immunotherapy, such as CIs, can play a role in risk stratifying patients for precision medicine and improve the outcome.

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.

Review - The impact of pharmacogenetics on the outcome of immune checkpoint inhibitors

The development of immune checkpoint inhibitors (ICIs) has a tremendous effect on the treatment options for multiple types of cancer. Nonetheless, there is a large interpatient variability in response, survival, and the development of immune-related adverse events (irAEs). Pharmacogenetics is the general term for germline genetic variations, which may cause the observed interindividual differences in response or toxicity to treatment. These genetic variations can either be single-nucleotide polymorphisms (SNPs) or structural variants, such as gene deletions, amplifications or rearrangements. For ICIs, pharmacogenetic variation in the human leukocyte antigen molecules has also been studied with regard to treatment outcome. This review presents a summary of the literature regarding the pharmacogenetics of ICI treatment, discusses the most important known genetic variations and offers recommendations on the application of pharmacogenetics for ICI treatment.

Brazilian autoimmune encephalitis network (BrAIN): antibody profile and clinical characteristics from a multicenter study

Background

The frequency of antibodies in autoimmune encephalitis (AIE) may vary in different populations, however, data from developing countries are lacking. To describe the clinical profile of AIE in Brazil, and to evaluate seasonality and predictors of AIE in adult and pediatric patients.

Methods

We evaluated patients with possible AIE from 17 centers of the Brazilian Autoimmune Encephalitis Network (BrAIN) between 2018 and 2022. CSF and serum were tested with TBAs and CBAs. Data on clinical presentation, complementary investigation, and treatment were compiled. Seasonality and predictors of AIE in adult and pediatric populations were analyzed.

Results

Of the 564 patients, 145 (25.7%) were confirmed as seropositive, 69 (12.23%) were seronegative according to Graus, and 58% received immunotherapy. The median delay to diagnosis confirmation was 5.97 ± 10.3 months. No seasonality variation was observed after 55 months of enrolment. The following antibodies were found: anti-NMDAR (n=79, 54%), anti-MOG (n=14, 9%), anti-LGI1(n=12, 8%), anti-GAD (n=11, 7%), anti-GlyR (n=7, 4%), anti-Caspr2 (n=6, 4%), anti-AMPAR (n=4, 2%), anti-GABA-BR (n=4, 2%), anti-GABA-AR (n=2, 1%), anti-IgLON5 (n=1, 1%), and others (n=5, 3%). Predictors of seropositive AIE in the pediatric population (n=42) were decreased level of consciousness (p=0.04), and chorea (p=0.002). Among adults (n=103), predictors of seropositive AIE were movement disorders (p=0.0001), seizures (p=0.0001), autonomic instability (p=0.026), and memory impairment (p=0.001).

Conclusion

Most common antibodies in Brazilian patients are anti-NMDAR, followed by anti-MOG and anti-LGI1. Only 26% of the possible AIE patients harbor antibodies, and 12% were seronegative AIE. Patients had a 6-month delay in diagnosis and no seasonality was found. Findings highlight the barriers to treating AIE in developing countries and indicate an opportunity for cost-effect analysis. In this scenario, some clinical manifestations help predict seropositive AIE such as decreased level of consciousness, chorea, and dystonia among children, and movement disorders and memory impairment among adults.

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.

Predictive Biomarkers for Checkpoint Inhibitor Immune-Related Adverse Events

Immune-checkpoint inhibitors (ICIs) are antagonists of inhibitory receptors in the immune system, such as the cytotoxic T-lymphocyte-associated antigen-4, the programmed cell death protein-1 and its ligand PD-L1, and they are increasingly used in cancer treatment. By blocking certain suppressive pathways, ICIs promote T-cell activation and antitumor activity but may induce so-called immune-related adverse events (irAEs), which mimic traditional autoimmune disorders. With the approval of more ICIs, irAE prediction has become a key factor in improving patient survival and quality of life. Several biomarkers have been described as potential irAE predictors, some of them are already available for clinical use and others are under development; examples include circulating blood cell counts and ratios, T-cell expansion and diversification, cytokines, autoantibodies and autoantigens, serum and other biological fluid proteins, human leucocyte antigen genotypes, genetic variations and gene profiles, microRNAs, and the gastrointestinal microbiome. Nevertheless, it is difficult to generalize the application of irAE biomarkers based on the current evidence because most studies have been retrospective, time-limited and restricted to a specific type of cancer, irAE or ICI. Long-term prospective cohorts and real-life studies are needed to assess the predictive capacity of different potential irAE biomarkers, regardless of the ICI type, organ involved or cancer site.

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.

HLA and tumour immunology: immune escape, immunotherapy and immune-related adverse events

PURPOSE

As molecules responsible for presenting antigens to T lymphocytes, leukocytes antigens (HLAs) play a vital role in cancer immunology. This review aims to provide current understanding of HLAs in tumour immunology.

METHODS

Perspectives on how HLA alterations may contribute to the immune escape of cancer cells and resistance to immunotherapy, and potential methods to overcome HLA defects were summarized. In addition, we discussed the potential association between HLA and immune-related adverse events (irAEs), which has not been reviewed elsewhere.

RESULTS

Downregulation, loss of heterogeneity and entire loss of HLAs are responsible for the immune escape of tumour cells. The strategies to overcome the HLA defects can be effective therapies of cancer. Compared with classical HLA-I, non-classical HLA-I molecules, such as HLA-E and HLA-G, appear to be more reliable predictors of prognosis, as they tend to play immunosuppressive roles in antitumor response. Relative diversified or high expression of classical HLA-I are potential predictors of favourable response of immunotherapy. Certain HLA types may be associated to enhanced affinity to self-antigen-mimicked tumour-antigens, thus may positively correlated to irAEs triggered by checkpoint inhibitors.

CONCLUSIONS

Further studies exploring the relationship between HLAs and cancer may not only lead to the development of novel therapies but also bring about better management of irAEs.

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

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

Hope, Cure, and Adverse Effects in Immunotherapy: Atezolizumab-Associated Encephalitis in Metastatic Small Cell Lung Cancer - A Case Report and Literature Review

Cancer immunotherapies have been revolutionary treatments in oncological disease. Such therapies include immune checkpoint inhibitors that target programmed cell death protein, ligands, and cytotoxic T-lymphocyte-associated antigen (CTLA-4). Increased use has led to recognition of immune-related adverse events. Such events are often distinct from the typical adverse events of traditional cancer therapies. Immune-related adverse events are more commonly found to affect the skin, gastrointestinal tract, and endocrine system. The incidence of these adverse events remains low for central nervous system effects. This article describes a case of atezolizumab-associated encephalitis in a patient with metastatic small cell lung cancer.

Association between germ-line HLA and immune-related adverse events

Background

In recent years, significant progress has been made in immune checkpoint inhibitors (ICIs). However, accompanied by remarkable efficacy, a growing number of immune-related adverse events (irAEs) also arose. The mechanism of irAEs remains unclear. Previous studies indicated a positive association between specific human leukocyte antigen (HLA) variants and irAEs. Therefore, we planned and initiated a large cohort study aiming to uncover the relationship between irAEs and divergent HLA types.

Methods

We screened all patients who have been treated in the clinical research ward, Cancer Hospital of the Chinese Academy of Medical Sciences. All participants were diagnosed with malignant tumors with complete AE follow-up data in the original electronic medical records. Sequencing libraries were generated using a customized panel, and four-digit formatted HLA alleles were extracted for further analysis. Association analysis was performed between HLA variants and different irAEs. We introduced two external reference groups and a non-irAE control group within the study cohort to control the type I error. We also explored the relationship between the zygosity of HLA genes, the evolutionary divergence of HLA class I genotype (HED), and irAEs.

Results

530 participants received at least two doses of ICIs. The median follow-up time was 10.3 months. 97% of patients received anti-PD-1/PD-L1 treatment. The occurrence of overall irAEs showed no significant difference between the HLA homozygous group and the HLA heterozygous group. We did not find any significant association between irAEs and HED. We found that some HLA types are associated with irAEs of different organs and detected a significant association between HLA-DRB3*01:01 and thrombocytopenia (OR 3.48 (1.19,9.42), p = 0.011), HLA-DPB1*04:02 and hypokalemia/hyponatremia (OR 3.44 (1.24,9.1), p = 0.009), leukopenia (OR 2.1 (0.92,4.8), p = 0.037), anemia (OR 2.33 (1.0,5.41), p = 0.026), HLA-A*26:01 and bilirubin elevation (OR 2.67 (0.92,8.31), p = 0.037).

Conclusions

IrAEs in specific organs and tissues may be associated with certain HLA types, while HLA heterogeneity has no significant influence on the happening of irAEs. More research is needed to explore the role of germline genetic changes in the risk assessment of irAEs.

Atezolizumab-induced Encephalitis in a Patient with Hepatocellular Carcinoma: A Case Report and Literature Review

We herein report a case of encephalitis in a 42-year-old woman with hepatocellular carcinoma following atezolizumab plus bevacizumab therapy. After two weeks of treatment, she was admitted for a high fever, impaired consciousness, and convulsive seizure refractory to diazepam. Magnetic resonance imaging revealed a hyperintense splenial lesion. A cerebrospinal fluid test excluded malignancy and infection. These findings were highly suggestive of a diagnosis of encephalitis due to atezolizumab, an immune-related adverse event. Steroid pulse therapy improved the fever and seizure. However, her incomplete right-sided paralysis and aphasia persisted. This is the first case report of encephalitis caused by atezolizumab plus bevacizumab therapy for hepatocellular carcinoma.

Immune-related adverse events in various organs caused by immune checkpoint inhibitors

Current cancer immunotherapies target immune checkpoint molecules such as the inhibitory receptor programmed cell death-1 (PD-1), one of its ligands, programmed cell death ligand-1 (PD-L1), and cytotoxic T-lymphocyte antigen 4 (CTLA-4), a competitive ligand for CD28 binding to stimulatory receptors CD80 and CD86. Multiple biological drugs use monoclonal antibodies targeting PD-1, PD-L1 and CTLA-4 as cancer immunotherapies. These are termed immune checkpoint inhibitors (ICIs). However, activation of the immune system by ICIs can induce the development of immune-related adverse events (irAEs), which can affect multiple organ systems. The most frequent irAEs are cutaneous and mimic various types of spontaneous skin disorders. Most irAEs are classified as autoimmune conditions mediated by ICI-activated CD8⁺ cytotoxic T cells, some of which are also related to activated B cells and production of pathogenic antibodies. Interestingly, blockade of CTLA-4 mainly induces activation of T cells and inhibition of T_reg cells. On the other hand, the mechanisms underlying anti-PD-1/PD-L1 ICI-induced irAEs are more complicated. PD-1 is a receptor expressed on T and B cells, which binds not only PD-L1, but also PD-L2. The role of PD-L1 is dominant in Th1 and Th17 immunity, while PD-L2 works mainly in Th2 immunity. Better understanding of the mechanisms underlying irAEs will allow for better management of irAEs and improve outcomes and quality of life in cancer patients.

Hypothesis for the development of immune-related adverse events in immune checkpoint inhibitors therapy

There are no explanations for the diversity in the development of certain immune-related adverse events (irAEs) with immune checkpoint inhibitors (ICI). The goal of this study is to search for possible predisposing factors that contribute to the development of certain autoimmune complications during anti-CTLA4 and anti-PD1/PD-L1 therapy. According to the keywords "checkpoint inhibitors, anti-CTLA4, anti-PD1/PD-L1, immune adverse events, paraneoplastic syndrome" the review and original articles published in the international databases to 2021were selected and studied. According to the analysis of the published papers, we consider that a key role in the difference in the types of irAEs lies in the specificity of the drug. The high prevalence of skin and gastrointestinal autoimmune complications can be explained by the presence of gut dysbacteriosis in patients before treatment and developed during the treatment. For the development of specific types of irAEs, a complex of predisposing factors is required, such as HLA-genotype, paraneoplastic syndromes, and the expression of PD-L1 in the thyroid gland in the case of anti-PD1 therapy.

How to diagnose and manage neurological toxicities of immune checkpoint inhibitors: an update

As the use of cancer immunotherapy with immune checkpoint inhibitors (ICIs) is expanding rapidly for the treatment of many tumor types, it is crucial that both neurologists and oncologists become familiar with the diagnosis and treatment of neurological immune-related adverse events (n-irAEs). These are rare complications, developing in their severe forms in only 1-3% of the patients, but are highly relevant due to their mortality and morbidity burden. The diagnosis of n-irAEs is-however-challenging, as many alternative diagnoses need to be considered in the complex scenario of a patient with advanced cancer developing neurological problems. A tailored diagnostic approach is advisable according to the presentation, clinical history, and known specificities of n-irAEs. Several patterns characterized by distinct clinical, immunological, and prognostic characteristics are beginning to emerge. For example, myasthenia gravis is more likely to develop after anti-programmed cell death protein 1 (PD-1) or anti-programmed cell death ligand 1 (PD-L1) treatment, while meningitis appears more frequently after anti-cytotoxic T lymphocyte antigen-4 (CTLA-4) therapy. Also, peripheral neuropathy and Guillain-Barré syndrome seem to be more common in patients with an underlying melanoma. Central nervous system disorders (CNS) are less frequent and are more often associated with lung cancer, and some of them (especially those with limbic encephalitis and positive onconeural antibodies) have a poor prognosis. Herein, we provide an update of the recent advances in the diagnosis and treatment of neurological toxicities related to ICI use, focusing on the exclusion of alternative diagnoses, diagnostic specificities, and treatment of n-irAEs.

Nivolumab-associated DRESS in a genetic susceptible individual

The use of immune checkpoint inhibitors (ICIs) is rising exponentially in numerous cancers, but immune-related adverse events can occur. We report a rare case of high-grade drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome developed stepwise in a patient with gastric cancer after nivolumab treatment. Subclinical myocarditis was sensitively detected by cardiovascular magnetic resonance 3 weeks after initiating nivolumab. Eruption, eosinophilia, and interstitial pneumonitis occurred 1 week later. Corticosteroids were started and his condition improved. Four months later, when he was still on steroids tapering off, acute kidney injury and sequential herpes zoster virus activation developed. Severe acute tubulointerstitial nephritis (ATN) with an intense infiltration of lymphocytes was observed on renal biopsy. In blood, a substantial shift to Th2 response, an increase of Th17 cells, and strikingly enriched granzyme B⁺ and perforin⁺ CD8⁺ T cells were detected at ATN onset. Serum interleukin (IL)-5, IL-17, interferon gamma, and IL-6 levels were consistently elevated. Further molecular profiling identified a DRESS risk allele human leukocyte antigen (HLA)-A*31:01 in this patient. His ATN responded favorably to a high dose of corticosteroids. In parallel, complete antitumor response was observed during the clinical course of DRESS. This is the first ever case report of nivolumab-associated DRESS syndrome with exploration of the mechanisms from the histopathological, cellular and molecular aspects. Nivolumab-induced DRESS may result from type IV hypersensitivity-related 'off-target effect' and PD-1 block-mediated 'on-target effect'. HLA risk alleles may constitute the genetic susceptible basis. HLA typing assay has the potential to screen susceptible individuals to avoid ICI-induced DRESS.

Neurological disorders associated with immune checkpoint inhibitors: an association with autoantibodies

Among diverse neurological immune-related adverse events (irAEs), autoimmune encephalitis, aseptic meningitis, Guillain-Barré syndrome (GBS), myasthenia gravis (MG), and myositis are particularly important. The clinical presentation may be different from that of patients with conditions unrelated to immune checkpoint inhibitors (ICIs). Many of the autoantibodies detected in patients' sera are committed to the pathogenesis, while the clinical significance of such autoantibodies in cases of neurological irAEs is different from the significance in cases of typical neuronal disorders. A broad range of clinical symptoms complicates the diagnosis of autoimmune encephalitis. The clinical features of aseptic meningitis induced by classical drugs are different from those of aseptic meningitis induced by ICIs. Although autoantibodies against synaptic receptors or neuronal cell surface proteins are not detected, anti-Ma2 antibodies, which are onconeural antibodies against intracellular proteins, are detected in patients with autoimmune encephalitis associated with ICIs. GBS induced by ICIs sometimes shows gradual progression and a relapse of symptoms, suggesting chronic inflammatory demyelinating polyneuropathy. Bulbar symptoms and myasthenic crisis are frequently observed in ICI-induced MG. Anti-acetylcholine receptor antibodies are found in only half of patients with MG occurring as an irAE. ICI-induced myositis is accompanied by ocular muscle symptoms, such as ptosis and diplopia, which can suggest MG. Patients receiving ICI treatment present clinical features and laboratory findings that represent a mixture of MG and myositis. Anti-striational antibodies may act as biomarkers in cases in which MG and myositis overlap. A correct understanding of neurological adverse events is required to achieve the best management of patients.

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

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