Steroid-Refractory Immune Checkpoint Inhibitor-Associated Myocarditis

Background Immune checkpoint inhibitors (ICIs) are a paradigm shift in cancer care, leveraging the immune system to target cancer cells. Myocarditis is an uncommon, highly morbid, and poorly understood complication of ICI therapy. We present a case of steroid-refractory ICI myocarditis and discuss management. Case An 88-year-old man with metastatic melanoma who had recently started pembrolizumab (anti-PD-1 antibody) reported fatigue. Testing revealed a creatine kinase of 3,005 U/L (normal Discussion Reports have indicated that myocarditis develops in 0.4-1% of ICI recipients. Mortality is estimated at 17-40%, far exceeding the approximately 4% mortality associated with non-ICI lymphocytic myocarditis. There are currently no prospective data to guide management. Expert opinion recommends therapy with high-dose glucocorticoids, followed by other immunosuppressive agents in cases of steroid-refractory disease, including anti-TNFα agents (infliximab), mycophenolate mofetil, intravenous immunoglobulin, plasmapheresis, tacrolimus, or anti-thymocyte globulin. Conclusion ICI myocarditis carries a high morbidity and mortality. Expert opinion recommends high-dose steroids as the initial therapy and the addition of other classes of immunosuppression in refractory cases. Prospective studies are critically needed to define the optimal treatment regimen.