Clinical applications of somatostatin analogs for growth hormone-secreting pituitary adenomas

Abstract

Ji-wen Wang,1,2 Ying Li,3 Zhi-gang Mao,1,2 Bin Hu,1,2 Xiao-bing Jiang,1,2 Bing-bing Song,4 Xin Wang,4 Yong-hong Zhu,4 Hai-jun Wang1,21Department of Neurosurgery and Pituitary Tumor Center, The First Affiliated Hospital, Sun Yat-sen University, 2Key Laboratory of Pituitary Adenoma in Guangdong Province, 3State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 4Department of Histology and Embryology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People's Republic of ChinaAbstract: Excessive growth hormone (GH) is usually secreted by GH-secreting pituitary adenomas and causes gigantism in juveniles or acromegaly in adults. The clinical complications involving cardiovascular, respiratory, and metabolic systems lead to elevated morbidity in acromegaly. Control of serum GH and insulin-like growth factor (IGF) 1 hypersecretion by surgery or pharmacotherapy can decrease morbidity. Current pharmacotherapy includes somatostatin analogs (SAs) and GH receptor antagonist; the former consists of lanreotide Autogel (ATG) and octreotide long-acting release (LAR), and the latter refers to pegvisomant. As primary medical therapy, lanreotide ATG and octreotide LAR can be supplied in a long-lasting formulation to achieve biochemical control of GH and IGF-1 by subcutaneous injection every 4–6 weeks. Lanreotide ATG and octreotide LAR provide an effective medical treatment, whether as a primary or secondary therapy, for the treatment of GH-secreting pituitary adenoma; however, to maximize benefits with the least cost, several points should be emphasized before the application of SAs. A comprehensive assessment, especially of the observation of clinical predictors and preselection of SA treatment, should be completed in advance. A treatment process lasting at least 3 months should be implemented to achieve a long-term stable blood concentration. More satisfactory surgical outcomes for noninvasive macroadenomas treated with presurgical SA may be achieved, although controversy of such adjuvant therapy exists. Combination of SA and pegvisomant or cabergoline shows advantages in some specific cases. Thus, an individual treatment program should be established for each patient under a full evaluation of the risks and benefits.Keywords: GH-secreting pituitary adenoma, somatostatin analogs, lanreotide ATG, octreotide LAR, growth hormone, insulin-like growth factor 1