Definition

A sustained-release (SR) formulation of the synthetic octapeptide and somatostatin analog octreotide, with potential growth hormone (GH) secretion-inhibiting and antineoplastic activities. Upon intramuscular administration of octreotide SR formulation Debio 4126, octreotide binds to and activates somatostatin receptors (SSTRs), including subtypes 2 and 5, which leads to an inhibition in the secretion of human growth hormone (hGH) in the pituitary gland and results in decreased production of insulin-like growth factor (IGF-1). This may inhibit IGF-1-mediated cell signaling pathways, and lead to apoptosis. Octreotide may also block key survival pathways such as the phosphatidylinositol 3-kinase (PI3K) and the mitogen-activated protein kinase (MAPK) signaling pathways. In addition, octreotide may inhibit tumor angiogenesis. Altogether, this may result in tumor cell death and inhibition of tumor cell proliferation and angiogenesis. SSTRs are overexpressed by some neuroendocrine and non-neuroendocrine tumor cells, and GH is over-produced in the pituitary gland in acromegaly.