Nivolumab is an immune-checkpoint inhibitor (ICI) that can induce unique treatment-related toxicities, such as immune-related adverse events (irAEs). Myocarditis is a serious irAE with an incidence between 0.06% and 1.14%. Although the peak onset of irAE is generally within three months from the start of treatment, we experienced an autopsy case of late-onset fulminant myocarditis caused by nivolumab in Epstein Barr virus-associated gastric cancer. Pathological complete remission of the primary lesion was confirmed by the autopsy. We should consider possible complications of cardiac irAEs, especially fulminant myocarditis, even beyond three months after starting ICI therapy.
Keywords: gastric cancer; immune-related adverse event; myocarditis; nivolumab.