Immune Checkpoint Inhibitor-associated Myocarditis Research Articles

Injury-induced myosin-specific tissue-resident memory T cells drive immune checkpoint inhibitor myocarditis

Cardiac myosin-specific (MyHC) T cells drive the disease pathogenesis of immune checkpoint inhibitor-associated myocarditis (ICI-myocarditis). To determine whether MyHC T cells are tissue-resident memory T (TRM) cells, we characterized cardiac TRM cells in naive mice and established that they have a distinct phenotypic and transcriptional profile that can be defined by their upregulation of CD69, PD-1, and CXCR6. We then investigated the effects of cardiac injury through a modified experimental autoimmune myocarditis mouse model and an ischemia-reperfusion injury mouse model and determined that cardiac inflammation induces the recruitment of autoreactive MyHC TRM cells, which coexpress PD-1 and CD69. To investigate whether the recruited MyHC TRM cells could increase susceptibility to ICI-myocarditis, we developed a two-hit ICI-myocarditis mouse model where cardiac injury was induced, mice were allowed to recover, and then were treated with anti-PD-1 antibodies. We determined that mice who recover from cardiac injury are more susceptible to ICI-myocarditis development. We found that murine and human TRM cells share a similar location in the heart and aggregate along the perimyocardium. We phenotyped cells obtained from pericardial fluid from patients diagnosed with dilated cardiomyopathy and ischemic cardiomyopathy and established that pericardial T cells are predominantly CD69+ TRM cells that up-regulate PD-1. Finally, we determined that human pericardial macrophages produce IL-15, which supports and maintains pericardial TRM cells.

Gasdermin-E-mediated pyroptosis drives immune checkpoint inhibitor-associated myocarditis via cGAS-STING activation

Immune checkpoint inhibitor (ICI)-induced myocarditis involves intensive immune/inflammation activation; however, its molecular basis is unclear. Here, we show that gasdermin-E (GSDME), a gasdermin family member, drives ICI-induced myocarditis. Pyroptosis mediated by GSDME, but not the canonical GSDMD, is activated in myocardial tissue of mice and cancer patients with ICI-induced myocarditis. Deficiency of GSDME in male mice alleviates ICI-induced cardiac infiltration of T cells, macrophages, and monocytes, as well as mitochondrial damage and inflammation. Restoration of GSDME expression specifically in cardiomyocytes, rather than myeloid cells, in GSDME-deficient mice reproduces ICI-induced myocarditis. Mechanistically, quantitative proteomics reveal that GSDME-dependent pyroptosis promotes cell death and mitochondrial DNA release, which in turn activates cGAS-STING signaling, triggering a robust interferon response and myocardial immune/inflammation activation. Pharmacological blockade of GSDME attenuates ICI-induced myocarditis and improves long-term survival in mice. Our findings may advance the understanding of ICI-induced myocarditis and suggest that targeting the GSDME-cGAS-STING-interferon axis may help prevent and manage ICI-associated myocarditis.

Unveiling Cellular Identities and Gene Expression Pathways in Overlapping Myocarditis and Myositis.

Immune checkpoint therapies can drive antitumor responses and benefit patients but can also induce life-threatening immune-related adverse events such as myocarditis and myositis. These immune-related adverse events are rare but carry substantial morbidity and mortality. In this issue, Siddiqui and colleagues use single-cell RNA and T-cell receptor sequencing to identify novel cellular subsets and propose various mechanisms that could contribute to the pathogenesis of immune checkpoint inhibitor-associated myocarditis and myositis. These new insights should help move the field toward the development of improved treatment and prevention options, ultimately improving patient outcomes. See related article by Siddiqui et al., p. 964 (1).

Central memory CD4+ T cells play a protective role against immune checkpoint inhibitor-associated myocarditis.

The widespread use of immune checkpoint inhibitors (ICIs) has demonstrated significant survival benefits for cancer patients and also carries the risk of immune-related adverse events. ICI-associated myocarditis is a rare and serious adverse event with a high mortality rate. Here, we explored the mechanism underlying ICI-associated myocarditis. Using the peripheral blood of patients with ICI therapy and of ICI-treated mice with transplanted tumours, we dissect the immune cell subsets and inflammatory factors associated with myocarditis. Compared to the control group, patients with myocarditis after ICI therapy showed an increase in NK cells and myeloid cells in the peripheral blood, while T cells significantly decreased. Among T cells, there was an imbalance of CD4/CD8 ratio in the peripheral blood of myocarditis patients, with a significant decrease in central memory CD4+ T (CD4+ TCM) cells. RNA sequencing revealed that CD4+ TCM cells in myocarditis patients were immunosuppressive cell subsets, which highly express the immunosuppressive factor IL-4I1. To elucidate the potential mechanism of the decrease in CD4+ TCM cells, protein array was performed and revealed that several inflammatory factors gradually increased with the severity of myocarditis in the myocarditis group, such as IL-1B/CXCL13/CXCL9, while the myocardial protective factor IL-15 decreased. Correlation analysis indicated a positive correlation between IL-15 and CD4+ TCM cells, with high expression of IL-15 receptor IL15RA. Furthermore, in vivo studies using an anti-PDL1 antibody in a mouse tumour model indicated a reduction in CD4+ TCM cells and an increase in effector memory-expressing CD45RA CD8+ T (TEMRA) cells, alongside evidence of cardiac fibrosis. Conversely, combining anti-PDL1 antibody treatment with IL-15 led to a resurgence of CD4+ TCM cells, a reduction in CD8+ TEMRA cells, and a mitigated risk of cardiac fibrosis. Our data highlight CD4+ TCM cells' crucial role in cardiac protection during ICI therapy. IL-15, IL-4I1, and CD4+ TCM cells can serve as therapeutic targets to reduce ICI-associated myocarditis in cancer patients.

Fatal Immune Checkpoint Inhibitor-associated Myocarditis Mimicking Infiltrative Cardiomyopathy in a 54-year-old Woman with Metastatic Melanoma

Introduction: Immune checkpoint inhibitors (ICI) have significantly improved cancer treatment outcomes, but cardiovascular complications such as ICI-associated myocarditis are a major concern. Diagnosing myocarditis requires integrating biomarkers, electrocardiogram (EKG), cardiac imaging, and endomyocardial biopsy. We present a case illustrating these diagnostic challenges, involving a female patient treated with pembrolizumab who developed fatal acute myocarditis mimicking infiltrative cardiomyopathy. Case report: A 54-year-old woman with mucosal melanoma, treated with pembrolizumab, was hospitalized in May 2023 due to dyspnea and elevated troponin levels. Initial cardiac workups were normal, but subsequent tests revealed borderline cardiac magnetic resonance imaging findings. In late May 2023, the patient was admitted with worsening dyspnea, elevated NT-pro-BNP, and severe hyperlactatemia. Imaging and endomyocardial biopsy confirmed acute myocarditis with atypical presentation, mimicking infiltrative cardiomyopathy. Despite aggressive immunosuppressive therapy, the patient’s condition deteriorated, resulting in cardiogenic shock and death seven days post-admission. Conclusion: This case underscores the diagnostic and management challenges of ICI-associated myocarditis, particularly with atypical presentations. It highlights the need for vigilant, comprehensive monitoring and further research to improve diagnostic and therapeutic strategies for managing these severe side effects in patients undergoing ICI therapy.

Case report: Regression after low-dose glucocorticoid therapy in a case of acute immune myocarditis induced by anti-PD-1 therapy for NSCLC

BackgroundPD-1 inhibitors exhibit efficacy in managing unresectable/metastatic driver gene-negative NSCLC, albeit with potential immune-related adverse events (irAEs). Among these, immune checkpoint inhibitor-associated myocarditis (ICI-M) is rare yet lethal. This study presents the initial successful instance of ICI-M in a lung cancer patient, rescued by low-dose glucocorticoids post-deterioration during treatment.Case summaryA 78-year-old male with a medical history of stage IV pT3N2M1 NSCLC underwent four cycles of palliative chemotherapy, resulting in stable disease (SD). Subsequent to declining further chemotherapy, the patient was transitioned to a targeted therapy regimen comprising Anlotinib in conjunction with PD-1 inhibitor immunotherapy. On the 26th day post-administration of the PD-1 inhibitor, the patient manifested Grade 2 immune-mediated myocarditis. Treatment encompassing 1mg/kg methylprednisolone combined with immunoglobulin shock therapy was initiated for 3 days, achieving symptomatic control. Nonetheless, upon tapering methylprednisolone dosage to 4–8mg/3–4d, the condition deteriorated, necessitating transfer to the intensive care unit. Methylprednisolone dosage was escalated to 80mg/day for 3 days, followed by gradual reduction by one-third to two-thirds weekly, culminating in the patient’s safe discharge from the hospital.ConclusionImmune-related myocarditis linked to checkpoint inhibitors is often managed effectively with high-dose glucocorticoid therapy. However, in Asian populations, low-dose glucocorticoids are increasingly utilized for salvage therapy, yielding favorable outcomes and improving prognosis compared to European populations.

The Cardio-Oncology Guideline - A Comprehensive Approach to Managing Cardiovascular Risks in Cancer Patients

The emerging field of cardio-oncology addresses the critical need for specialized cardiovascular care in cancer patients, given the overlapping risk factors and potential cardiovascular complications of oncological therapies. In collaboration with the European Hematology Association (EHA), the European Society for Therapeutic Radiology and Oncology (ESTRO), and the European Society of Cardiology (ESC), the first cardio-oncology guideline was developed and published in 2022. This guideline comprises 272 recommendations covering risk stratification before therapy initiation, monitoring during oncological treatment, and the diagnosis and treatment of therapy-associated cardiovascular side effects.A significant innovation in this guideline is the comprehensive risk stratification approach, which categorizes patients into low, moderate, and high-risk groups based on therapy-specific factors. This allows for tailored cardiovascular care during therapy, with varying frequencies of follow-up examinations depending on the patient's risk level. Notably, the guideline emphasizes the importance of interdisciplinary collaboration between oncologists and cardiologists to optimize patient outcomes.Overall, the cardio-oncology guideline represents a significant advancement in addressing the complex cardiovascular needs of cancer patients. Its comprehensive recommendations and emphasis on interdisciplinary care underscore the importance of optimizing cardiovascular health throughout the oncological treatment journey.This review provides an overview of the guidelines and updates on the risk stratification and therapy of patients with immune checkpoint inhibitor-associated myocarditis (ICIM), as well as the role of statins in protecting against anthracycline-associated cardiotoxicity.

Prognostic value of cardiovascular magnetic resonance in immune checkpoint inhibitor-associated myocarditis: A systematic review and meta-analysis.

Immune checkpoint inhibitors (ICI)are increasingly used in the first-line treatment of malignant tumors. There is increasing recognition of their cardiotoxicity and, in particular, their potential to lead to myocarditis. Cardiovascular magnetic resonance (CMR)can quantify pathological changes, such as myocardial edema and fibrosis. The purpose of this systematic review and meta-analysis was to examine the evidence for the roles of CMR in predicting prognosis in ICI-associated myocarditis. PubMed, Cochrane Library, and Web of Science databases were searched until October 2023 for published works investigating the relationship between CMR parameters and adverse events in patients with ICI-associated myocarditis. The analysis included studies reporting the incidence of late gadolinium enhancement (LGE),T1 values, T2 values, and CMR-derived left ventricular ejection fraction (LVEF).Odds ratios (OR)and weighted mean differences (WMD)were combined for binary and continuous data, respectively. Newcastle-Ottawa Scale was used to assess the methodological quality of the included studies. Five cohort studies were included (average age 65-68 years; 25.4% female). Of these, four studies were included in the meta-analysis of LGE-related findings. Patients with major adverse cardiovascular events (MACE)had a higher incidence of LGE compared with patients without MACE (OR = 4.18, 95% CI: 1.72-10.19, p = 0.002). A meta-analysis, incorporating data from two studies, showed that patients who developed MACE exhibited significantly higher T1 value (WMD = 36.16 ms, 95% CI: 21.43-50.89, p < 0.001) and lower LVEF (WMD = - 8.00%, 95% CI: -13.60 to -2.40, p = 0.005). Notably, T2 value (WMD = -0.23 ms, 95% CI: -1.86 to -1.39, p = 0.779) was not associated with MACE in patients with ICI-related myocarditis. LGE, T1 value, and LVEF measured by CMR imaging have potential prognostic value for long-term adverse events in patients with ICI-related myocarditis.

Abstract 2480: Treatment of steroid-refractory immune checkpoint inhibitor-associated myocarditis: A case series of 18 patients

Abstract Background: Immune checkpoint inhibitors (ICI) have improved survival in various malignancies but are associated with significant immune-related adverse events (irAE). Up to 2% of patients on ICI develop ICI-myocarditis, which is associated with significant mortality. Treatment guidelines for ICI-myocarditis are limited. The initial treatment starts with high dose glucocorticoids, but the subsequent lines of treatment remain ill-defined. Methods: We retrospectively identified patients at our institution from 2021 onwards who were treated for ICI-myocarditis and who had an inadequate response to steroid treatment (thus steroid refractory). Baseline characteristics, laboratory and imaging data, and outcomes were reviewed. Results: Of the 34 patients diagnosed with ICI-myocarditis, 18 (53%) were steroid refractory. Amongst the 18, 11 were female and 7 were male, with a mean age of 73. Cancer types included head and neck, thoracic, urologic, gynecologic, and gastrointestinal. Patients had received a median of 2 ICI doses prior to myocarditis presentation. Thirteen (72%) patients had prior or concurrent irAE, most commonly neurologic or neuromuscular such as myasthenia gravis/myositis (44%) or hepatitis (33%). For initial treatment, 14 (41%) patients received a max dose of methylprednisolone 1g/day, while 4 (12%) received smaller doses (less than 500mg/day). Following steroids, the most common next treatment was mycophenolate mofetil (MMF) for 9 (50%), IVIG for 6 (33%), and Abatacept for 3 patients (17%). MMF was most often added and uptitrated to wean steroids, with 8 (44%) patients being able to be tapered off after a median duration of 112 days. IVIG was more commonly used for patients with concomitant neurologic symptoms while Abatacept was more commonly used for patients presenting with grade IV toxicities. The most encountered side effects following steroids were hyperglycemia, weight gain, adrenal insufficiency, and myopathy and following MMF were cytopenias and hypertension. The median survival since myocarditis diagnosis was 412 days. The patient with the longest documented survival of 645 days received IVIG and then MMF following steroids. Two patients with severely immunosuppression-resistant myocarditis responded well to tofacitinib, with one patient living 521 days after diagnosis (after methylprednisolone, IVIG, MMF, Abatacept, Tofacitinib) and one still alive more than 400 days after diagnosis (after methylprednisolone, MMF, Abatacept, IVIG, Infliximab, Tofacitinib). Conclusion: Steroid-refractory ICI-associated myocarditis can be responsive to other immunosuppression agents. Our case series, one of the largest studies of this population, highlights their effectiveness and the populations they can cater to. Adjunctive treatments for ICI-myocarditis require further study to identify right doses and order of treatment. Citation Format: Ritujith Jayakrishnan, Samantha Brongiel, Darren Luon, Stephanie Halene, Jennifer M. Kwan. Treatment of steroid-refractory immune checkpoint inhibitor-associated myocarditis: A case series of 18 patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2480.

Cardiac magnetic resonance-based layer-specific strain in immune checkpoint inhibitor-associated myocarditis.

To assess the different imaging characteristics between corticosteroid-sensitive (CS) and corticosteroid-refractory (CR) immune checkpoint inhibitor-associated myocarditis (ICIaM) with cardiac magnetic resonance (CMR) and the potential CMR parameters in the early detection of CR ICIaM. Thirty-five patients diagnosed with ICIaM and 30 age and gender-matched cancer patients without a history of ICI treatment were enrolled. CMR with contrast was performed within 2days of clinical suspicion. Left ventricular ejection fraction (LVEF) and late gadolinium enhancement (LGE) were assessed by CMR. LV sub-endocardial (GLSendo) and sub-epicardial (GLSepi) global longitudinal strains were quantified by offline feature tracking analysis. CS and CR ICIaM were defined based on the trend of Troponin I and clinical course during corticosteroid treatment. All 35 patients presented with non-fulminant symptoms upon initial assessment. Twenty patients (57.14%) were sensitive, and 15 (42.86%) were refractory to corticosteroids. Compared with controls, 22 patients (62.86%) with ICIaM developed LGE. LVEF decreased in CR ICIaM compared with the CS group and controls. GLSendo (-14.61±2.67 vs. -18.50±2.53, P<0.001) and GLSepi (-14.75±2.53 vs. -16.68±2.05, P<0.001) significantly increased in patients with CR ICIaM compared with the CS ICIaM. In patients with CS ICIaM, although GLSepi (-16.68±2.05 vs. -19.31±1.80, P<0.001) was impaired compared with the controls, GLSendo was preserved. There was no difference in CMR parameters between LGE-positive and negative groups. LVEF, GLSendo, and GLSepi were predictors of CR ICIaM. When LVEF, GLSendo, and GLSepi were included in multivariate analysis, only GLSendo remained an independent predictor of CR ICIaM (OR: 2.170, 95% CI: 1.189-3.962, P=0.012). A GLSendo of ≥-17.10% (sensitivity, 86.7%; specificity, 80.0%; AUC, 0.860; P<0.001) could predict CR ICIaM in the ICIaM cohort. Kaplan-Meier analysis showed that in patients with impaired GLSendo of ≥-17.10%, cardiovascular adverse events (CAEs) occurred much earlier than in patients with preserved GLSendo of <-17.10% (Log-rank test P=0.017). CR and CS ICIaM demonstrated different functional and morphological characteristics in different myocardial layers. An impaired GLSendo could be a helpful parameter in early identifying corticosteroid-refractory individuals in the ICIaM population.

Identification of shared mechanisms and targets between immune checkpoint inhibitor-associated myocarditis and autoimmune myocarditis

Objective This study aimed to explore the shared mechanisms and targets between immune checkpoint inhibitor-associated myocarditis (ICIM) and autoimmune myocarditis. Methods Relevant data were retrieved from public datasets and Gene Expression Omnibus (GEO) database. Gene set enrichment analysis (GSEA) of differentially expressed genes (DEGs) was used to identify significant shared signaling pathways between ICIM and non-ICI associated autoimmune myocarditis (NICIAM) represented by ICIM model and experimental autoimmune myocarditis (EAM) model, respectively. Cell type enrichment analysis and immune infiltration analysis by clusterProfiler and ImmuCellAI were performed to identify critical immune cell component involved in ICIM and NICIAM. Additionally, core shared genes across ICIM and NICIAM were identified and validated by various models and methods. Results Interferon-γ response, inflammatory response and allograft rejection signaling were identified as the shared signaling pathways associated with ICIM and NICIAM. Enrichment analysis of cell type supported an important role of increased infiltration of T cells and macrophages in both ICIM and NICIAM. However, the predominant increase of infiltrated T cells was CD4+ T cells in NICIAM, while that were CD8+ T cells in ICIM. Core shared genes Lck and Cd3d expression were found increased in both ICIM and NICIAM, and Lck inhibition was further identified and validated as potential therapeutic approach. Conclusions Our study initially established a comorbidity model to identify potential molecular mechanism including interferon-γ response, inflammatory response and allograft rejection signaling accounting for the concerns of myocarditis risk in patients with preexisting autoimmune disease (PAD) receiving ICI treatment, and supported the therapeutic potential of targeting Lck or Cd3d.

Peripheral biomarkers to assess risk, severity, and prognosis of immune checkpoint inhibitor-associated myocarditis: a retrospective clinical study.

Immune checkpoint inhibitor-associated myocarditis (ICI myocarditis) is an infrequent but potentially fatal immune-related adverse event. This study aimed to identify valuable indicators for risk prediction and evaluation of disease severity and outcomes. A total of 79 patients with severe or mild ICI myocarditis and 158 controls without post-ICI immune-related adverse events were enrolled in this retrospective study. The clinical application value of a series of simple biomarkers were tested. Higher levels of the systemic immune-inflammation index (SII), neutrophil-to-eosinophil ratio (NER), aspartate transferase-to-albumin ratio (AAR), and lactic dehydrogenase-to-albumin ratio (LAR) at myocarditis onset were associated with severe disease conditions. In the receiver operating characteristic analysis, biomarkers areas under the curve (AUC) close to or greater than 0.8 were LAR (AUC: 0.810) and AAR (AUC: 0.806). Patients with higher SII, AAR, and LAR also exhibited poorer overall survival. The SII, NER, AAR, and LAR before the last ICI treatment increased relative to baseline in patients with ICI myocarditis, whereas no significant changes in the tested biomarkers were observed in the control group. For SII, AAR, and LAR, high ratios of the biomarker levels before the last ICI to baseline was associated with the incidence of myocarditis. Surveillance of these economical biomarkers during ICI therapy might contribute to the risk prediction of ICI myocarditis, as well as the assessment of disease severity and prognosis.

Autoantibody profiling of patients with immune checkpoint inhibitor-associated myocarditis: a pilot study.

Immune checkpoint inhibitor (ICI)-associated myocarditis is a rare, but potentially fatal, immune-related adverse event. Hence, identifying biomarkers is critical for selecting and managing patients receiving ICI treatment. Serum autoantibodies (AAbs) in patients with ICI myocarditis may serve as potential biomarkers for predicting, diagnosing, and prognosing ICI myocarditis. We conducted a pilot study using a human proteome microarray with approximately 17,000 unique full-length human proteins to investigate AAbs associated with ICI myocarditis. AAb profiling was performed using sera collected from three patients with ICI myocarditis before the start of ICI treatment and immediately after myocarditis onset. All patients received anti-programmed death-1 antibody monotherapy. At baseline, 116, 296, and 154 autoantigens reacted positively to immunoglobulin G (IgG) in the serum samples from Cases 1, 2, and 3, respectively. Among these proteins, the recombination signal-binding protein for the immunoglobulin kappa J region (RBPJ) was recognized by all three samples, and 32 autoantigens were recognized by any two of the three samples. At the onset of ICI myocarditis, compared to baseline, 48, 114, and 5 autoantigens reacted more strongly with IgG in the serum samples from Cases 1, 2, and 3, respectively. Among these, antibodies against eukaryotic translation initiation factor 4E binding protein 3 (EIF4EBP3) were the most upregulated, with a 38-fold increase. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses highlighted that B-cell receptor signaling, leukocyte transendothelial migration, and thymus development were among the most affected pathways. Enrichment analyses using DisGeNET revealed that proteins reacting to AAbs detected in patients with ICI myocarditis are associated with several diseases, including dilated cardiomyopathy and muscle weakness. This pilot study provides the first integrated analysis of serum AAb profiling in patients with ICI myocarditis and identifies novel candidate markers associated with an increased risk of developing ICI myocarditis and its pathogenesis. However, our results require further independent validation in clinical trials involving a larger number of patients.

Advances in research on molecular markers in immune checkpoint inhibitor-associated myocarditis.

Immune checkpoint inhibitors (ICIs) play a crucial role in the immunotherapy of malignant tumors, preventing immune evasion by tumor cells and activating autoimmune cells to eliminate the tumor. Despite their proven effectiveness in antitumor therapy, potential immune-related adverse effects must be recognized, particularly ICI-associated myocarditis (ICIAM). ICIAM is the most lethal form of organ immunotoxicity, with a significant impact on short-term mortality. However, ICIAM is predominantly asymptomatic or mildly nonspecific. It is difficult to diagnose, especially due to the lack of unique molecular markers. This article aims to provide a comprehensive overview of the progress made in identifying molecular markers for ICIAM.

Investigate the role of neutrophil extracellular traps in immune checkpoint inhibitor-associated myocarditis with programmed death protein-1 inhibitors involvement

Objective: To investigate the role of neutrophil extracellular traps (NETs) in immune checkpoint inhibitor-associated myocarditis (ICIAM) with programmed death protein-1 (PD-1) inhibitors involvement, and to explore the therapeutic potential of targeting NETs in the treatment of ICIAM. Methods: Thirty 6-week-old male BALB/c mice were randomly divided into control group (n=10), myocarditis group (n=10), and treatment group (n=10). Apart from the control group, each mouse was subcutaneously injected with 100 μl of complete Freund's adjuvant containing 250 μg of mouse cardiac troponin I peptide on the 1st and 7th day. Starting on the 8th day, PD-1 inhibitor (15 μg/per mouse) was intraperitoneally injected every other day for a total of 5 times. Since 1 day before the beginning of PD-1+TnI injection, the treatment group was injected with PF-1355 (50 mg·kg-1·d-1) for 16 consecutive days. The mice's general state was observed during the whole process. Real-time fluorescence quantitative PCR (RTFQ-PCR) was carried out to evaluate the transcriptional regulation of neutrophil related chemokines, NETs, pyronecrosis related factors and proinflammatory cytokines. Immunohistochemistry, immunofluorescence and western blot were applied to determine the changes of pyrosis related molecules. Echocardiography showed the differences of main cardiac indexes while cardiac pathology compared the degree of inflammatory infiltration in 3 gruops. Results: The immunofluorescence intensity of myocardial NETs in the myocarditis group was significantly increased compared to the control group mice (2.49±0.08 and 0.99±0.26, P<0.001). The protein expression levels of pyroptosis-related NLRP3, cleaved-Caspase 1, Caspase 1, cleaved-GSDMD, GSDMD, IL-1β and IL-18 in myocardial tissue of the model group were higher than those of the control group (all P<0.05). After treatment with PF-1355, compared to the myocarditis group, the left ventricular ejection fraction (LVEF) (73.58%±5.31% and 58.12%±3.19%, P<0.001) and left ventricular fraction shortening (LVFS) (39.78%±4.31% and 33.89%±2.19%, P<0.001) increased. H-E staining showed a reduction in inflammatory infiltration area in the treatment group compared to the myocarditis group (30.12%±3.57% and 14.92%±2.46%, P<0.001). The immunofluorescence intensity of NETs decreased in the treatment group compared to the myocarditis group (2.52±0.04 and 1.03±0.05, P<0.001). The levels of NLRP3 and other pyroptosis-related molecules were downregulated in the treatment group compared to the myocarditis group (all P<0.05). Conclusions: NETs lead to myocardial cell pyroptosis by activating the NLRP3 inflammasome in PD-1 inhibitor-associated myocarditis. The specific MPO inhibitor PF-1355 shows a therapeutic potential by regulating the formation of NETs, decreasing NLRP3 level and relieving myocardial pyroptosis, thus reducing myocardial damage.

Comprehensive analysis of risk factors for the severity of immune checkpoint inhibitor-associated myocarditis in cancer patients

Abstract Purpose To explore the predictive significance of patients’ clinical features and examination results, including blood laboratory tests, echocardiogram, cardiovascular magnetic resonance (CMR), and electrocardiogram (ECG), for the severity of immune checkpoint inhibitors (ICIs)-associated myocarditis. Methods Data from a real-world cohort of 81 cancer patients who developed ICI-associated myocarditis after immunotherapy were retrospectively analyzed. Myocarditis of Common Terminology Criteria for Adverse Events (CTCAE) grades 3-5 and the development of the major adverse cardiovascular event (MACE) were set as endpoints. Logistic regression was used to evaluate each parameter’s value in predicting myocarditis of grades 3-5 and MACE. Results Eventually, CTCAE grades 3-5 and MACE developed in 43/81 (53.1%) and 28/81 (34.6) cases, respectively. The occurrence of CTCAE grades 3-5 (HR, 95%CI: 4.48, 2.02-9.91, p&amp;lt;0.001) and MACE (HR, 95%CI: 16.21, 6.93-37.94, p&amp;lt;0.001) were strongly related to patients’ overall survival from ICI-associated myocarditis to death. The likelihood of CTCAE grades 3-5 and MACE increased with the accumulation of organs affected by the ICI-associated adverse events and initial clinical symptoms. Concurrent systematic therapies during ICI treatment did not raise the risk of myocarditis severity, while prior chemotherapy did. Apart from the classical cardiac markers, such as myoglobin, brain natriuretic peptide, and troponin T, a higher neutrophil ratio was also related to poorer cardiac outcomes, whereas a higher lymphocyte and monocyte ratios were predictors of favorable cardiac outcomes. Besides, the CD4+ T cell ratio and CD4/CD8 ratio were negatively related to CTCAE grades 3-5. Several cardiovascular magnetic resonance parameters were associated with myocarditis severity. In contrast, the predictive value of echocardiography and electrocardiogram was weak. Conclusions This study comprehensively evaluated the prognostic value of different patients’ clinical factors and examination results and discovered several predictors of severe ICI-associated myocarditis, which will facilitate early detection of severe ICI-associated myocarditis in patients receiving immunotherapy.

Clinical characteristics and prognostic impact of immune checkpoint inhibitor-associated myocarditis in advanced non-small cell lung cancer.

Myocarditis is a rare immune-related adverse events (irAEs) with high mortality rates, with few reports on its clinical characteristics and prognostic impact. This study designed to explore the associations between cardiac parameters and outcomes of myocarditis in advanced non-small cell lung cancer (NSCLC) who treated with immune checkpoint inhibitor (ICI). Fourteen patients diagnosed with ICI-associated myocarditis by clinicians were admitted to the study analysis. By Cox univariate and multivariate survival analyses, potential risk factors for the development of severe myocarditis were identified. Survival analysis was also performed to explore the prognosis of patients with myocarditis. Among patients with myocarditis, higher B-type natriuretic peptide (BNP) levels (P= 0.04) and conduction block (P= 0.03) were associated with progression to severe myocarditis. In addition, high lactate dehydrogenase (LHD) levels (P= .04) and myocarditis onset within 2 months (P= 0.02) were prognostic factors of severe myocarditis. The median progression-free survival (PFS) time and median overall survival (OS) time for all patients were 5.9 months and 18.5 months, respectively. However, there were no statistical differences between mild and severe cohorts in terms of PFS and OS (PFS: 4.5 vs. 8.5 months, P= 0.17; OS: 21.3 vs. 18.5months, P= 0.36). And we found that the earlier occurrence of myocarditis, worse PFS prognosis (4.5 months vs. 10.5 months, P= 0.008), while no difference in OS (18.5 months vs. 21.3 months, P= 0.35). Compared to mild myocarditis, severe myocarditis presented with higher BNP levels and cardiac conduction abnormalities. In addition, patients with mild and early myocarditis tended to have better survival rates.

Correction to: Diagnostic Value of the International Society of Cardio-Oncology Definition for Suspected Immune Checkpoint Inhibitor-Associated Myocarditis.

Correction to: Diagnostic Value of the International Society of Cardio-Oncology Definition for Suspected Immune Checkpoint Inhibitor-Associated Myocarditis.

Abstract P3060: Modeling Immune Checkpoint Inhibitor Associated Myocarditis In Vitro

Introduction: Immune checkpoint inhibitor-associated myocarditis (ICI myocarditis) is a severe side effect of treating malignancies with immune checkpoint inhibitors. Patients suffering from ICI myocarditis often display an extraordinarily high mortality rate. Establishing a clinically relevant model to address the lack of identifiable risk factors, screening tests, or effective treatments is critically urgent. Hypothesis: Human ICI myocarditis can be accurately modeled in vitro. Methods and Results: We present the first cell culture-based model of ICI myocarditis. We use a novel method to co-culture human iPSC-derived cardiomyocytes (hiPSC-CM), human peripheral blood mononuclear cells, and immune checkpoint inhibitors to recapitulate critical aspects of clinical ICI myocarditis. Using this platform, we show rapid, significant cardiomyocyte necrosis after model initiation. We observe substantial disruption to hiPSC-CM cell morphology and sarcomere structure, and we use powerful multi-electrode array technology to define contractile functions and electrophysiological changes, demonstrating the critical similarities between this cell-based ICI myocarditis model and patient myocarditis. Our model also reveals an increased risk of arrhythmia, recapitulating, in vitro , the primary cause of death in patients suffering from ICI myocarditis. Finally, we demonstrate that this hiPSC-CM-based “model in a dish” can be rescued pharmacologically and identify specific leukocyte populations required for myocarditis development. In summary, we present the first in vitro model of ICI myocarditis and demonstrate its scalability, validity, patient relevance, and reproducibility. Utilizing the model can aid in accomplishing precision medicine objectives and holds significant potential for preventing and treating ICI myocarditis.

Treatment of Immune Checkpoint Inhibitor-associated Myocarditis.

Immune checkpoint inhibitors (ICIs) are a form immunotherapy where the negative regulators of host immunity are targeted, thereby leveraging the own immune system. ICIs have significantly improved cancer survival in several advanced malignancies, and there are currently more than 90 different cancer indications for ICIs. Most patients develop immune-related adverse events during ICI therapy. Most are mild, but a small subset of patients will develop severe and potentially fatal immune-related adverse events. A serious cardiovascular complication of ICI therapy is myocarditis. Although the incidence of myocarditis is low, mortality rates of up to 50% have been reported. The mainstay of ICI-associated myocarditis treatment is high-dose corticosteroids. Unfortunately, half of patients with myocarditis do not show clinical improvement after corticosteroid treatment. Also, high doses of corticosteroids may adversely impact cancer outcomes. There is an evidence gap in the optimal second-line treatment strategy. Currently, there is a paradigm shift in second-line treatment taking place from empirical corticosteroid-only strategies to either intensified initial immunosuppression where corticosteroids are combined with another immunosuppressant or targeted therapies directed at the pathophysiology of ICI myocarditis. However, the available evidence to support these novel strategies is limited to observational studies and case reports. The aim of this review is to summarize the literature, guidelines, and future directions on the pharmacological treatment of ICI myocarditis.