Occult checkpoint inhibitor myocarditis during adjuvant nivolumab plus ipilimumab: a smoldering but severe toxicity

Checkpoint inhibitor myocarditis is a rare but life-threatening toxicity of immunotherapy, occasionally manifesting as persistent troponin elevation. Dual checkpoint blockade with ipilimumab and nivolumab has been found to induce immune-related myocarditis in patients with metastatic melanoma. We herein report a case of smoldering immune-related myocarditis in a 54-year-old male after a single infusion of nivolumab plus ipilimumab as adjuvant treatment for completely resected stage IV melanoma. High-dose steroid treatment resulted in decrease in the levels of cardiac enzymes, without any major complications.