Isolated ACTH deficiency induced by cancer immunotherapy: a systematic review

Immunotherapy with immune checkpoint inhibitor (ICI) monoclonal antibodies has shown to be an effective therapeutic alternative in several malignant tumors. However, adverse effects related to an activation of the immune system may accompany ICI therapy. Among the immune-related adverse events (irAEs) are autoimmune endocrine adverse effects, such as thyroiditis, and hypophysitis. Secondary adrenal insufficiency due to isolated ACTH deficiency (IAD) has also been recently reported to be associated with ICI antibodies. We carried out a systematic review of IAD cases induced by cancer immunotherapy published to date using PubMed's database. We selected 35 articles that reported 60 cancer patients diagnosed with IAD induced by ICI therapy. The prevalence was higher in men (ratio 1.6/1). Mean age at diagnosis was 63.2 ± 11.6 (range,30-87). Melanoma was the tumor most commonly reported (35%) followed by lung (28.3%) and kidney cancer (18.3%). The ICI monoclonal antibody most frequently associated was nivolumab in monotherapy (60%), followed by pembrolizumab (18.3%). Median (IQR) time to develop IAD after starting ICI therapy was 6 (4-8) months. The main symptoms at IAD diagnosis were fatigue (82.8%) and anorexia (67.2%). Hyponatremia (68%) and eosinophilia (31.8%) were the laboratory abnormalities most frequently associated with IAD. Pituitary magnetic resonance imaging (MRI) was normal in most patients (93%). Thyroiditis was the most prevalent (35%) endocrine irAE associated with IAD. In conclusion, ICI-induced IAD is a rare and potentially life-threatening condition that must be taken into account whenever treatment with immunotherapy in cancer patients is started due to their potential serious prognostic implications.