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