Identification of Pathogenic Immune Cell Subsets in Checkpoint Inhibitor-induced Myocarditis

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies used widely to activate the immune system against tumor cells. Despite their therapeutic benefits, ICIs are known to cause immune-related adverse events (irAE) such as myocarditis, a rare but serious side effect with up to 50% mortality. To identify pathogenic immune subset(s) responsible for ICI myocarditis and other irAE, we performed single cell mass cytometry (CyTOF) on peripheral blood mononuclear cells from patients and controls with irAE including four patients with ICI myocarditis.