Type 1 Diabetes, ACTH Deficiency, and Hypothyroidism Simultaneously Induced by Nivolumab Therapy in a Patient with Gastric Cancer: A Case Report

Nivolumab, a fully human IgG4 immune checkpoint inhibitor (ICI) antibody, has been approved for a variety of cancers. Several endocrine-associated immune-related adverse events have been reported, but the incidence rate is relatively low. This is a case of a patient with gastric cancer who underwent nivolumab therapy, leading to type 1 diabetes as well as adrenocorticotropic hormone (ACTH) deficiency and hypothyroidism almost simultaneously. A 70-year-old man with no previous history of diabetes was treated with nivolumab monotherapy for gastric cancer in November 2018. After 8 courses of nivolumab, he was diagnosed with type 1 diabetes associated with ICI; consequently, insulin therapy was initiated in March 2019. In April 2019, he was transported to hospital due to suffering from prolonged hypoglycemia, disturbed consciousness, and fever. He frequently experienced episodes of hypoglycemia, with poor controlled glycemia. His disturbed consciousness and fever also sustained. Further investigation of his hormones revealed low cortisol and ACTH levels, as well as hypothyroidism. His blood glucose control was improved after the introduction of hydrocortisone and thyroid hormone; he became alert and afebrile. In January 2020, he received a followed-up in an outpatient setting under insulin, hydrocortisone, and thyroid replacement therapy. Endocrine defect associated with ICIs, especially type 1 diabetes or ACTH deficiency, is a rare condition. To the best of our knowledge, this is the 1st case of multiple endocrinopathies simultaneously induced by nivolumab. Various endocrine concomitant defects should be taken into consideration when treating with nivolumab.