Introduction: Immune-checkpoint inhibitors have become an increasingly popular form of systemic therapy for cancer treatment. Their use has proven to be so effective that certain regimens have gained approval as first-line therapy for various solid tumor types. The most common and well-studied forms of immunotherapy include agents that target cytotoxic T-lymphocyte antigen-4, programmed death-1, and programmed death ligand-1. These therapies act by blocking signaling between immune cells and cancer cells which subsequently augment T cell-mediated destruction of tumor cells.
Case report: Here, we report a case of a 77-year-old black male with no history of or risk factors for diabetes mellitus who presented with acute onset of diabetic ketoacidosis after beginning immunotherapy with nivolumab for metastatic high-grade neuroendocrine tumor of the lung. He was admitted and treated for diabetic ketoacidosis but required prolonged use of an insulin infusion with frequent need of intravenous dextrose due to labile blood sugars. The patient was eventually discharged and discontinued further immunotherapy with nivolumab.
Discussion: Due to the unique mechanisms by which immune-checkpoint inhibitors cause immune-mediated destruction of tumor cells, clinicians may be challenged with their associated autoimmune complications referred to as immune-related adverse events. In particular, the incidence of endocrine dysfunction following immune-checkpoint inhibitor therapy is approximately 12%, with the development of insulin-dependent diabetes mellitus being a rare complication. Increasing awareness of immune-related adverse events is essential for the early recognition and effective management of patients who present with life-threatening complications related to immune-checkpoint inhibitor therapy.
Keywords: Nivolumab; checkpoint inhibitor; diabetic ketoacidosis; immunotherapy; neuroendocrine tumor.