Comparative Transcriptomics of Immune Checkpoint Inhibitor Myocarditis Identifies Guanylate Binding Protein 5 and 6 Dysregulation

SIMPLE SUMMARY: Immune checkpoint inhibitors are revolutionizing cancer treatment, but lead to the occurrence of immune related adverse events including ICI-associated myocarditis (ICIM). To date, transcriptional alterations of this rare phenomenon with a high mortality rate are not characterized. 19 ICIM patients at the University Hospitals Heidelberg and Kiel showed diverse clinical presentations. Comparative transcriptomics was able to distinguish ICIM patients from patients with dilated cardiomyopathy or virus-induced myocarditis in the upregulation of 3784 genes. The RNA-based analyses and immunohistology revealed a potential role of an inflammasome-regulating protein, GBP5, as a potential pathomechanism in cardiomyocytes. These alterations may help to diagnose ICIM and potentially enable to identify patients at risk in an early stage. ABSTRACT: Immune checkpoint inhibitors (ICIs) are revolutionizing cancer treatment. Nevertheless, their increasing use leads to an increase of immune-related adverse events (irAEs). Among them, ICI-associated myocarditis (ICIM) is a rare irAE with a high mortality rate. We aimed to characterize the transcriptional changes of ICIM myocardial biopsies and their possible implications. Patients suspected for ICIM were assessed in the cardio-oncology units of University Hospitals Heidelberg and Kiel. Via RNA sequencing of myocardial biopsies, we compared transcriptional changes of ICIM (n = 9) with samples from dilated cardiomyopathy (DCM, n = 11), virus-induced myocarditis (VIM, n = 5), and with samples of patients receiving ICIs without any evidence of myocarditis (n = 4). Patients with ICIM (n = 19) showed an inconsistent clinical presentation, e.g., asymptomatic elevation of cardiac biomarkers (hs-cTnT, NT-proBNP, CK), a drop in left ventricular ejection fraction, or late gadolinium enhancement in cMRI. We found 3784 upregulated genes in ICIM (FDR < 0.05). In the overrepresented pathway ‘response to interferon-gamma’, we found guanylate binding protein 5 and 6 (compared with VIM: GBP5 (log2 fc 3.21), GBP6 (log2 fc 5.37)) to be significantly increased in ICIM on RNA- and protein-level. We conclude that interferon-gamma and inflammasome-regulating proteins, such as GBP5, may be of unrecognized significance in the pathophysiology of ICIM.