Case Report: Successful treatment of steroid-refractory immune checkpoint inhibitor associated myocarditis with tofacitinib.

The advent of immune checkpoint inhibitors (ICIs) has revolutionized cancer treatment but is associated with immune-related adverse events (irAEs) that can involve multiple organ systems.Steroid-refractory immune checkpoint inhibitor associated myocarditis, defined as persistent or progressive myocardial injury despite high-dose corticosteroids requiring escalation of immunosuppression, represents a life-threatening clinical challenge with limited therapeutic options. This case report describes a 75-year-old female patient with deficient mismatch repair sigmoid colon adenocarcinoma who developed severe multi-organ irAEs, including myositis, hepatitis, and steroid-refractory myocarditis 25 days after receiving QL1706 (a PD-1/CTLA-4 bispecific antibody). Initial intervention with high-dose glucocorticoid pulse therapy combined with intravenous immunoglobulin failed to control the myocardial injury. The clinical course was further complicated by endocrine involvement and hematological toxicity following second-line immunosuppression with mycophenolate mofetil. After tofacitinib administration, the patient's clinical symptoms and laboratory findings showed significant improvement. Notable adverse effects included oral mucositis, diarrhea, and a pulmonary fungal infection, which were managed supportively. This case highlights the potential role of tofacitinib in managing complex, steroid-refractory multi-organ irAEs. However, the significant infection risk underlines the necessity for vigilant monitoring and prophylactic strategies. Further prospective studies are needed to define the efficacy and safety of JAK inhibitors in this setting.