Antiangiogenic Therapy in Pancreatic Neuroendocrine Tumors

In recent years, many progresses have been pursued in the management of advanced pancreatic neuroendocrine tumor (pNET); most of them were prompted by increasing knowledge of biology of these neoplasms, including the identification of promising biological targets for therapy. PNETs belong to a group of rare neoplastic diseases. They originate from neuroendocrine system cells and are very heterogeneous regarding anatomic localization and aggressiveness. Recently, many efforts have been particularly focused on the identification of pathologic pathways and innovative drugs in order to treat patients with unresectable, metastatic disease, in progressive well-differentiated pNETs. Chemotherapy remains the mainstay of treatment of poorly-differentiated pNETs. The positive results obtained by sunitinib, a multi-targeted tyrosine kinase receptor inhibitor of vascular endothelial growth factor receptor (VEGFR) 1-3, platelet-derived growth factor receptor (PDGFR), c-kit, RET, colony stimulating factor-1 receptor (CSF-1R) and Fms-like tyrosine kinase 3 (FLT3), with direct antitumor and antiangiogenic effects, have highlighted the importance of tumor angiogenesis inhibition in controlling these tumors. Angiogenesis is a crucial process during tumor progression and plays a key role in development of metastasis. The role of angiogenesis in the malignant spread of pNET cells is finally supported by in vivo studies conducted on the RIP1-Tag2 mouse model. In this mini-review, we focus on the two pharmaceuticals that have given the most interesting results in clinical trials: bevacizumab and sunitinib. These drugs are changing the management of advanced pNETs.