Steroid hormones as modulators of anti-tumoural immunity

Immune evasion is a hallmark of cancer progression but the role of steroid hormones in this evasion has long been underrated. This oversight is particularly notable for glucocorticoids given that exogenous glucocorticoids remain a cornerstone therapy in various oncological treatment regimens, supportive care and treatment of immune-related adverse events caused by immune-checkpoint inhibitors. Cortisol, the main endogenous glucocorticoid in humans, is secreted by the adrenal cortex in response to stress. Additionally, cortisol and its inactive metabolite cortisone can be interconverted to further modulate tissue-dependent glucocorticoid action. In the past 5 years, intratumoural production of glucocorticoids, by both immune and tumour cells, has been shown to support tumour immune evasion. Here, we summarize current progress at the crossroads of endocrinology and immuno-oncology. We outline the known effects of steroid hormones on different immune cell types with a focus on glucocorticoids and androgens. We conclude with options for pharmaceutical intervention, including the engineering of cell-based therapies that resist the immunosuppressive action of steroid hormones. Overall, local steroid production and metabolism are emerging elements of tumour immune suppression that are potentially amenable to therapeutic intervention. Targeting steroid hormones to enhance anticancer therapies could increase their efficacy but will require expertise in endocrine care.