Dopamine Agonists for the Treatment of Pituitary Tumors: From Ergot Extracts to Next Generation Therapies

Abstract

Dopamine agonists are a key tool in the therapeutic arsenal of endocrinologists worldwide. They exert their effects by binding to dopamine 2 (D2) receptors expressed by pituitary tumor cells, to modulate hormonal secretion and tumor size. They are the established first-line treatment for prolactinomas which express high levels of D2 receptors. Growing data supports their use as an adjuvant treatment option for other pituitary tumors including growth hormone, adrenocorticotrophic hormones, thyroid hormone secreting adenomas and non-functional pituitary tumors, all of which have been shown to express D2 receptors as well, albeit to varying extents. For those pituitary tumors inadequately treated by dopamine agonist alone, combined agonism of D2 and somatostatin receptors, represent a new frontier in clinical development. Here we review the development and role of dopamine agonist for the treatment of prolactinomas, the literature supporting their adjuvant use for the treatment of all other pituitary tumors, and recent progress in the development of the next generation of chimeric compounds that target D2 and other receptor subtypes highly expressed on pituitary tumor cells.