Immune Checkpoint Inhibitor Therapy Associated Hypophysitis

Ipilimumab is a monoclonal antibody directed against CTLA4 T-lymphocyte antigen used as cancer therapy. Immune-related adverse events are common side effects and may include hypophysitis-related hypopituitarism. The clinical features of six patients with ipilimumab-induced hypophysitis (IH) are described. The clinical features of IH reported in clinical trials, including the incidence of IH by gender and the likelihood of adrenal axis recovery, are summarized. Following the development of IH, most patients remain on glucocorticoid replacement despite efforts to withdraw therapy. Analysis of gender information in published clinical trials suggests that men are more prone to developing IH than women, and few patients fully recover the pituitary-adrenal axis function. Ipilimumab and other drugs within its class are likely to be used to treat many forms of cancer. Endocrinologists should anticipate a significant increase in the incidence of autoimmune hypophysitis. Strategies for early detection of IH and long-term management should be considered.