The use of a GH receptor antagonist in patients with acromegaly resistant to somatostatin analogs.

Pegvisomant, a GH receptor antagonist, is a new pharmaceutical approach to acromegaly. It enables IGF-I levels to return in the age- and sex-reference range in approximately 90% of patients. This new approach is particularly beneficial in those patients who do not experience control of hormone hypersecretion after surgery and/or medical treatment with somatostatin analogs. In our preliminary experience, out of 16 patients unsuccessfully operated on by transsphenoidal surgery and resistant to 40-mg octreotide-LAR or 120-mg lanreotide for at least 6 months, 13 normalized their IGF-I levels within 6 months from treatment beginning. Normalization of IGF-I levels was accompanied by a significant decrease of ring size. We did not observe any increase of tumor remnant in this short period of treatment. In two cases we observed a significant increase of liver transaminases levels. In conclusion, more than 80% of patients with acromegaly unsuccessfully treated by surgery or currently available somatostatin analogs can achieve normal IGF-I levels after short-term treatment with pegvisomant.