[A Case of Thyroid Dysfunction and Isolated Adrenocorticotropin Deficiency after Nivolumab Therapy for Malignant Melanoma].

The patient was a 34-year-old woman. Surgical resection and chemotherapy had been performed on diagnosis of malignant melanoma in year X-9. Chronic thyroiditis was diagnosed in year X-8, but her thyroid function was normal. In November of the year X-1, the patient, who had metastasis to the left lung and the left main bronchus and radically unresectable metastases with distant metastases, was treated with the anti-PD-1 antibody nivolumab. In December X-1, we initiated levothyroxine sodium for hypothyroidism after the patient suffered indolent thyroiditis due to nivolumab. In March X, the nivolumab treatment was stopped because it proved to be ineffective, then in April, anorexia, fever, and general malaise were noted. Cortisol 5.0 and ACTH 17.5 were confirmed by blood test, and the patient was diagnosed with adrenal insufficiency and was admitted to the hospital. Head MRI showed no organic lesions, and a stress test showed abnormalities only in a CRH test (low response to both ACTH and cortisol). The patient was diagnosed with isolated ACTH deficiency due to nivolumab. Side effects of thyroid dysfunction due to nivolumab are frequently observed in Japan at a rate of 14.3%, and overseas at 5.9%. However, secondary adrenocortical dysfunction is observed in overseas clinical trials at a frequency of only about 0.3%. There are few reports of such complications, and we report this as a rare case.