Effectiveness of Additional Immunosuppressive Drugs for Corticosteroid-refractory Immune Checkpoint Inhibitor-induced Myocarditis: Two Case Reports

Immune checkpoint inhibitors (ICIs) improve the outcomes of several types of cancer. However, they are also associated with various immune-related adverse events including myocarditis. ICI-induced myocarditis is a rare, potentially life-threatening adverse event. We herein report two cases of corticosteroid-refractory ICI-induced myocarditis. In both cases, additional immunosuppressive therapies, such as intravenous immunoglobulin and tacrolimus, successfully resolved myocarditis. Given the corticosteroid-refractory nature of these cases, we suggest that prompt addition of other immunosuppressive drugs to corticosteroid therapy should be considered in the treatment of ICI-induced myocarditis.