Immune checkpoint inhibitor-induced hypophysitis: clinical and biochemical features

Immune checkpoint inhibitors are a very promising novel class of immune response-regulating drugs for cancer treatment. Hypophysitis is one of their most common immune-related adverse events, occurring in a significant proportion of patients. Since this is a potentially severe entity, regular hormone monitoring is recommended during treatment to allow for a timely diagnosis and adequate treatment. Identification of clinical signs and symptoms, such as headaches, fatigue, weakness, nausea and dizziness, can also be key for its recognition. Compressive symptoms, such as visual disturbances, are uncommon, as is diabetes insipidus. Imaging findings are usually mild and transient and can easily go unnoticed. However, the presence of pituitary abnormalities in imaging studies should prompt closer monitoring, as these can precede clinical manifestations. The clinical importance of this entity relates mainly to the risk of hormone deficiency, especially ACTH, which occurs in the majority of patients and is rarely reversible, requiring lifelong glucocorticoid replacement therapy.