Targeted therapy for gastrointestinal and pancreatic neuroendocrine tumors

Extensive investigation of neuroendocrine tumors (NETs) has only started in recent years. The increased attention to this issue is due to the more frequent detection of NETs as a result of diagnostic methods improvement. The limited effectiveness of chemotherapy for well-differentiated advanced metastatic NETs of gastrointestinal tract (GIT) and pancreas demonstrates the need for development of the new and more effective treatment options. Recent studies on specific biological features of NETs have led to the development of the new targeted therapies which take into account high vascularization and overexpression of specific growth factors and related tyrosine kinase receptors. Thus, studying the mTOR TSC2, PTEN and PIK3CA signaling pathways opens up the new opportunities in the treatment of gastrointestinal or pancreatic NETs, especially in case of inoperable or metastatic tumors. Targeted therapy, which specifically inhibits growth factor receptors and related signaling pathways, is a promising approach to drug therapy for patients with gastrointestinal or pancreatic NETs. This review summarizes the state of the art and prospects for using targeted therapy, and describes clinical studies in the treatment of gastrointestinal and pancreatic NETs.