Abstract
Primary adrenal failure (Addison's disease) is a rare complication of immune checkpoint inhibitor (ICI) therapy. Untreated - and also sometimes under adequate hydrocortisone replacement therapy - the levels of ACTH (Adrenocorticotropic hormone) and MSH (Melanocyte stimulating hormone) are elevated. This may be a reason for concern in patients with malignant melanoma (MM): Melanocortin receptors bind to ACTH and the different isoforms of MSH. For example, the melanocortin 1 receptor (MC1R) is overexpressed in many human melanoma cells. Since it is also involved in the proliferation of melanoma cells, the elevated levels of ACTH and its proteolytic cleavage product α-MSH typical for primary failure may lead to an activation of the receptor and, thus, put MM patients that suffered from primary adrenal failure after ICI therapy at an elevated risk for recurrence or an unfavorable course of the disease. Novel dual-release hydrocortisone therapy results in lower ACTH (and most probably lower α-MSH) levels due to the more physiological mode of hydrocortisone release. Given that the concern raised in this hypothesis is confirmed in future investigations, patients who suffer from primary adrenal failure after ICI therapy may benefit from a dual-release hydrocortisone replacement regimen.