Successful use of equine anti-thymocyte globulin (ATGAM) for fulminant myocarditis secondary to nivolumab therapy

Immune-mediated myocarditis is an uncommon adverse effect of immune checkpoint inhibition and is associated with a high rate of mortality. In this reported case, a 64-year-old woman with right temporo-parietal glioblastoma IDH-WT was treated with nivolumab, temozolomide and radiation therapy on a clinical trial. She developed malignant arrhythmias secondary to histologically confirmed severe immune-mediated myocarditis. She was treated with equine anti-thymocyte globulin (ATGAM) due to development of malignant arrhythmias refractory to high-dose corticosteroids. This report describes the only case of immune-mediated myocarditis treated with ATGAM resulting in a favourable outcome. Use of ATGAM should be considered in cases of steroid-refractory immune-mediated myocarditis and administered in close consultation with a cardiac transplant team experienced in the use of this agent.