Pegvisomant: new preparation. A last resort in acromegaly

(1) The first-line treatment for acromegaly is transsphenoidal surgery. As an adjunct to surgery, and for patients with inoperable tumours, the first-line drug therapy is a somatostatin analogue (octreotide or lanreotide). (2) Pegvisomant, a growth hormone (GH) receptor antagonist, is licensed for patients who have a poor response to surgery and/or radiation therapy and in whom somatostatin analogue therapy has failed. (3) There are no published comparative trials evaluating pegvisomant as alternative for patients who have already tried a somatostatin analogue. Most of the evaluation data comes from a single randomised, placebo-controlled trial in 112 patients treated for three months. It showed that pegvisomant, at a dose of 10 mg to 20 mg/day subcutaneously, normalised the level of insulin-like growth factor type 1 (IGF-1) and improved some symptoms. However, the patients were very heterogeneous, and no information was provided on the efficacy of previous treatments. This trial does not provide enough evidence to support the approved indication. (4) Pegvisomant lowers the IGF-1 level but also increases the GH level. An increase in the size of the pituitary adenoma, due to the resulting hyperfunctioning, was observed in four of the 160 patients treated in clinical trials. (5) Evaluation data on pegvisomant does not resolve the question of possible hepatic toxicity. (6) In practice, pegvisomant therapy is justified for patients with serious complications of acromegaly and who have no other treatment options. But the patients concerned, who are few in number, must be closely monitored and included in an appropriate register.