Rhabdomyolysis as a Predominant Multisystem Serious Immune-Related Adverse Event Induced by Sintilimab: A Case Report and Literature Review.

Cancer treatment has entered the era of immunotherapy after surgery, radiotherapy, chemotherapy, and targeted therapy. The immune-related adverse events (irAEs) associated with immune checkpoint inhibitors (ICIs) have become a significant concern in clinical practice, given the broad application of these agents. This article reports a case of immune polymyositis involving the myocardium and rhabdomyolysis in a patient with lung adenocarcinoma combined with brain metastases treated with sintilimab. In addition, there was simultaneous involvement of other systems with immune-associated hepatitis, thyrotoxicosis, and secondary hypoadrenalism. After high-dose corticosteroid shock therapy administration, the patient's symptoms and indicators improved significantly.