Targeting the somatostatin receptor in pituitary and neuroendocrine tumors.

INTRODUCTION: Neuroendocrine and pituitary tumors are uncommon tumors that develop from cells of the (neuro-)endocrine system. They can secrete hormones, leading to typical symptoms and syndromes. The cornerstone of antisecretory treatment for neuroendocrine and growth hormone-secreting pituitary tumors consists of somatostatin analogs, which target the somatostatin receptors that are expressed on the tumor cell membrane. Somatostatin analogs activate the second messenger pathways that inhibit hormone secretion and may also delay tumor growth. AREAS COVERED: Recent developments in the field of somatostatin analogs and promising new angles in neuroendocrine tumor treatment are discussed. The recently approved somatostatin analog pasireotide and promising new analogs KE108 and somatoprim are reviewed. Further, innovative developments in the field of receptor manipulation, such as epigenetic manipulation and viral somatostatin receptor subtype-2 expression vectors, are discussed, as well as oncolytic viruses specifically targeting neuroendocrine tumor cells. EXPERT OPINION: In addition to the development of novel somatostatin analogs and refining treatment with existing somatostatin analogs, alternative treatments targeting the somatostatin receptors that aim at increasing the number of somatostatin receptors should be explored as well, thereby broadening treatment perspectives and increasing options for prolonging survival.