Pegvisomant is a GH antagonist used in acromegaly in gigantism. Pegvisomant is a modified GH molecule with pegylation to increase half-life and nine amino acid substitutions to modify GH receptor affinity and dimerization. Pegvisomant leads to an IGF1 decrease. It is administered subcutaneously every day with a median dose of 15 mg/day in meta-analysis. This treatment is indicated in acromegaly or gigantism in case of resistance to somatostatin analogs. This drug leads to a control of acromegaly in 90% of patients in phase III study and about 70% of patients in real-life study. In gigantism, only 50% of children are controlled with pegvisomant. It is a well-tolerated treatment with hepatic side effects in 3% of cases, headache in 2% of cases, and lipohypertrophy in 3% of cases. Pegvisomant does not act on adenoma size, and 6% of increasing tumour size is observed. Indeed, pegvisomant is an antagonist of GH receptor with a good efficacy which can be used alone or in association with somatostatin analog or cabergoline if acromegaly is not controlled by a somatostatin analog.
Part of the book: Growth Disorders and Acromegaly