CTLA4 and myocarditis: A recent study showed that the application of high doses programmed cell death protein 1 (PD‐1) inhibitor and CTLA‐4 inhibitor caused significant systemic inflammation and multiorgan immune‐related adverse events including myocarditis in cynomolgus monkeys.[6] Furthermore, PD‐1 deficiency resulted in the development of fatal myocarditis in MRL/MpJ‐Faslpr mice, which was associated with considerable infiltration of T cells, myeloid cells, and autoantibodies against cardiac α‐myosin.[7]