Molecular Targeted Therapy for Gastroenteropancreatic Neuroendocrine Tumors

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are generally considered rare tumor. According to the recent studies, the number of patients had been increasing and frequently diagnosed as advanced stages. Surgery is the only possible way to cure GEP-NENs. However, the indication of surgical treatment for the patients with advanced GEP-NENs is limited, and for those patients other therapies such as radiofrequency ablation, transarterial chemoembolization, and/or systemic medical treatment are selected. Molecular targeted therapy is one of the promising treatments for low-grade or well-differentiated GEP-NENs. Phase III randomized studies of molecular targeted agents, such as somatostatin analogues, mTOR inhibitor, and tyrosine kinase inhibitor, had been conducted, and those studies demonstrated the antiproliferative effect in patients with GEP-NENs. Octreotide long-acting release, somatostatin analogue, was approved for gastrointestinal NENs. Lanreotide Autogel, another somatostatin analogue, was approved for GEP-NEN. Everolimus, mTOR inhibitor, was approved for GEP-NENs. Sunitinib, tyrosine kinase inhibitor, was approved for pancreatic NENs. Despite these advances, some tumors show intrinsic resistance to these targeting therapies. The arrival of novel treatment, which gives more options for the patient with GEP-NENs, is desired.