Pancreatic endocrine tumors (PETs) are uncommon tumors with an annual incidence <1 per 100 000 person-years in the general population. The PETs that produce hormones resulting in symptoms are designated as functional. The majority of PETs are non-functional. Of the functional tumors, insulinomas are the most common, followed by gastrinomas. The clinical course of patients with PETs is variable and depends on the extent of the disease and the treatment rendered. Patients with completely resected tumors generally have a good prognosis, and aggressive surgical therapy in patients with advanced disease may also prolong survival. The epidemiology, prognosis, and established and novel prognostic markers of PETs are reviewed.
Thorvardur R Halfdanarson, Joseph Rubin, Michael B Farnell, Clive S Grant and Gloria M Petersen
Judith A Gilbert, Laura J Adhikari, Ricardo V Lloyd, Joseph Rubin, Paul Haluska, Joan M Carboni, Marco M Gottardis and Matthew M Ames
Neuroendocrine (carcinoid) tumors (NETs) are endocrine neoplasms occurring most frequently in gastrointestinal and bronchopulmonary (BP) systems. The majority of patients present with advanced disease for which few treatment options exist. We assessed 104 NETs (74 cases) for biomarkers targeted by anticancer drugs under development for other forms of cancer. Activating mutations were assessed in epidermal growth factor receptor (EGFR), stem cell factor receptor (KIT), and platelet-derived growth factor receptor alpha (PDGFRA), as well as non-response mutations in KRAS. Copy number of EGFR and HER-2/neu was quantified with fluorescence in situ hybridization. Immunohistochemical analyses were performed for EGFR, KIT, PDGFRA, somatostatin receptor subtypes 2A and 5 (SSTR5), vascular endothelial growth factor receptor 1, mammalian target of rapamycin (mTOR), insulin-like growth factor 1 receptor (IGF1R), heat shock protein 90 (Hsp90), and transforming growth factor-β receptor 1 (TGFBR1). NETs lacked HER2-overexpression predictive of anti-HER2 response and KIT and PDGFRA activating mutations indicative of imatinib sensitivity. High EGFR aneusomy (20% of all cases) and elevated EGFR copy number (39%) were found, but few KRAS mutations associated with non-response to anti-EGFR therapy (3%). Hsp90, TGFBR1, IGF1R, and SSTR5 exhibited highest levels of immunohistochemical staining in the largest percents of tumors. In subsequent in vitro studies, anticancer drug 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) (targeting Hsp90) inhibited proliferation of BP NET lines NCI-H727, NCI-H720, and NCI-H835 with IC50 values of 70.4, 310, and 788 nM respectively; BMS-754807 (targeting IGF1R/IR) inhibited growth with IC50 values of 428 nM, 2.8 μM, and 1 μM. At growth-inhibiting concentrations, 17-AAG (24 h) induced loss of EGFR and IGF1R in the IGF1R-expressing NCI-H727 line, and BMS-754807 (24 h) inhibited constitutive IGF1R autophosphorylation. Our results support further research into Hsp90, IGF1R, and EGFR as targets for developing new anticancer therapeutics for some NETs.