A cancer patient treated with the immune drug nivolumab developed a rare form of adrenal failure because the pituitary gland stopped making ACTH. The problem was spotted using a hormone test that includes GHRP-2, and the brain scan looked normal, which can make diagnosis tricky.

Currently, nivolumab (an anti-programmed cell death-1 receptor monoclonal antibody) is available for many types of advanced cancers in Japan. However, there have been few detailed case reports about endocrine-related adverse events of this therapy. Here, we report a patient with metastatic renal cell carcinoma who presented with secondary adrenal insufficiency following nivolumab therapy. Endocrinological assessment by rapid adrenocorticotropic hormone (ACTH) and corticotropin-releasing hormone (CRH) tests revealed that the patient's disorder was a secondary adrenal insufficiency due to pituitary dysfunction. Moreover, the results of the thyrotropin-releasing hormone (TRH), luteinizing hormone-releasing hormone (LH-RH) and growth hormone-releasing peptide-2 (GHRP-2) tests showed that only the ACTH function was destroyed (isolated ACTH deficiency). The magnetic resonance imaging (MRI) findings of hypophysitis, which is the major cause of isolated ACTH deficiency, usually demonstrate enlargement of the pituitary gland. However, the MRI findings of our case showed no abnormalities of the pituitary gland and stalk. Therefore, not only oncologists, but also other specialists, including doctors in emergency units, should have knowledge of this specific feature. Our clinical observation could be useful to avoid a delay in diagnosis and to treat life-threatening adverse effects of nivolumab therapy, such as secondary adrenal insufficiency.