Isolated autoimmune adrenocorticotropic hormone deficiency: From a rare disease to the dominant cause of adrenal insufficiency related to check point inhibitors

Objective: Immune checkpoint inhibitors have introduced a new and heterogeneous class of immune-related adverse effects, with the endocrine system being a predominant target for autoimmunity. Autoimmune hypothalamic-pituitary-adrenal axis (HPA) diseases induced by checkpoint inhibitors are being increasingly recognized. We aimed to characterize the spectrum of checkpoint associated hypothalamic-pituitary-adrenal axis endocrinopathies. Design: A retrospective cohort study of a tertiary cancer center. Methods: Patients were characterized for HPA axis abnormalities based on clinical and pituitary axes evaluation. The risk for developing HPA endocrinopathies was compared by log- rank test, by the time since checkpoint inhibitors initiation. Additionally, the risk for developing HPA endocrinopathies after adjusting for covariates was assessed using multivariable logistic regression analysis. Results: Among 1615 patients, fourteen (0.87%) patients developed isolated adrecocorticotrophic' hormone deficiency (IAD), six (0.37%) - hypophysitis and no case of adrenalitis was identified. IAD presented with mild and non-specific symptoms, mainly asthenia. In multivariable analysis, exposure to both PD-1/PD-L1 and Ipilimumab and female gender were associated with an increased odds ratio (OR) for developing IAD (6.98 [95% CI 2.38-20.47, p < .001] and 3.67 [95% CI 1.13-11.84, p = .03]), respectively. Conclusions: IAD, a rare disease before the immunotherapy era, has become a predominant checkpoint related HPA axis autoimmune injury. Despite its life threatening potential, IAD may be missed due to its subtle presentation. Patients exposed to Ipilimumab and PD-1/PD-L1 in combination or sequentially and women have an increased risk for developing IAD.