Clinical use of a growth hormone receptor antagonist in the treatment of acromegaly.

The elucidation of the mechanisms by which growth hormone (GH) interacts with its receptor has facilitated the design of compounds that function as GH-receptor antagonists. One such compound, B2036, has been conjugated to polyethylene glycol to produce a drug, pegvisomant, that has a powerful ability to lower circulating concentrations of insulin-like growth factor I (IGF-I), the principal mediator of GH action, in patients with acromegaly and to improve the symptoms and signs associated with GH excess. This article describes the mechanism of action of GH-receptor antagonists, reviews the preclinical and clinical data on the use of pegvisomant and discusses some of the challenges that lie ahead in judging the efficacy of a treatment that, unlike established therapies for acromegaly, does not aim to modify the underlying cause of acromegaly, namely excess GH secretion, but aims to lower serum IGF-I levels to normal.