Future directions in the treatment of neuroendocrine tumors: consensus report of the National Cancer Institute Neuroendocrine Tumor clinical trials planning meeting

Bevacizumab plus octreotide and metronomic capecitabine in patients with metastatic well-to-moderately differentiated neuroendocrine tumors: the XELBEVOCT study

Background

We assessed the activity and toxicity of the XELBEVOCT regimen in patients with metastatic well-to-moderately differentiated neuroendocrine neoplasms (WMD-NEN). Ancillary studies evaluated hypertension, proteinuria, and vascular endothelial growth factor (VEGF) polymorphisms in predicting progression-free survival (PFS) and the predictive role of serum vitamin D in progression-free survival and proteinuria onset.

Methods

This prospective phase 2 study included 45 patients with WMD-NEN arising from various primary sites. The treatment regimen was octreotide long-acting release (LAR), 20 mg monthly, metronomic capecitabine, 2000 mg/daily, and intravenous bevacizumab, 5 mg/kg every 2 weeks, without interruption for 9 months. Bevacizumab was continued until disease progression.

Results

Partial response was obtained in 8 patients (17.8%, 95% confidence interval [CI], 6.4%-28.2%); tumor response was more frequent in pancreatic than in non-pancreatic malignancies. The median PFS was 14.9 months; median overall survival was not attained. Biochemical and symptomatic responses were observed in 52.9% and 82.3% of cases, respectively. The treatment was well tolerated. Grade 3 toxicities included hand and foot syndrome (11.1%), proteinuria (4.4%), and renal toxicity (2.2%). Proteinuria (all grades) was correlated with longer PFS (p = 0.017). There was an inverse relationship between proteinuria and vitamin D levels. VEGF polymorphisms were not associated with patient outcome.

Conclusion

The XELBEVOCT regimen is active and well tolerated in patients with metastatic WMD-NEN. Proteinuria correlated with hypovitaminosis D status and was the best predictive factor of treatment efficacy.

Trial registration

Trial registration number NCT01203306.

177 Lu-Dota-octreotate radionuclide therapy of advanced gastrointestinal neuroendocrine tumors: results from a phase II study

PURPOSE

We evaluated the activity and safety profile of (177)Lu-Dotatate peptide receptor radionuclide therapy (Lu-PRRT) in patients with advanced, well-differentiated (G1-G2) gastrointestinal neuroendocrine tumors (GI-NETs).

METHODS

Forty-three patients with radiological tumor progression at baseline and a positive Octreoscan® completed the treatment with Lu-PRRT, resulting in the cumulative activity of 18.5 or 27.8 GBq in five cycles. Total activity was scheduled on the basis of kidney function or bone marrow reserve.

RESULTS

Twenty-five (58 %) patients were treated with a "standard" Lu-PRRT full dosage (FD) of 25.7 GBq (range 22.2-27.8), while the remaining 18 patients (42 %) who, at enrolment, showed a higher probability of developing kidney or bone marrow toxicity received a reduced dosage (RD) of 18.4 GBq (range 14.4-20.4). According to SWOG criteria, the overall response was complete response (CR) in (7 %) cases and stable disease (SD) in 33 (77 %), with a disease control rate (DCR) of 84 %. Median response duration was 25 months (range 7-50). Median progression-free survival (PFS) was 36 months (95 % CI 24-nr), and median overall survival (OS) has not yet been reached. Remarkably, none of the patients, including those at a higher risk of toxicity, showed side-effects after either dosage of Lu-PRRT.

CONCLUSION

Lu-PRRT was shown to be an effective therapeutic option in our patients with advanced progressive GI-NETs, showing an 84 % DCR (95 % CI 73-95) that lasted for 25 months and a PFS of 36 months. Both activities of 27.8 GBq and 18.5 GBq proved safe and effective in all patients, including those with a higher probability of developing kidney or bone marrow toxicity.

Advanced digestive neuroendocrine tumors: metastatic pattern is an independent factor affecting clinical outcome

OBJECTIVES

The objective of this study was to determine the impact of different metastatic spread patterns on outcome in advanced digestive neuroendocrine tumors (NETs).

METHODS

This was a retrospective analysis of patients with stage IV NETs, classified as group 1 (unilobar liver metastases), group 2 (bilobar liver metastases), group 3 (extra-abdominal metastases). End points were overall survival (OS) and progression-free survival (PFS). Risk factor analysis was performed using Cox proportional hazard model.

RESULTS

Of the 229 patients, 135 (58.9%) had pancreatic, and 94 (41.1%) small bowel NETs: 32 (13.9%) were included in group 1, 179 (78.2%) in group 2, and 18 (7.9%) in group 3. Median Ki67 was 4.5%. Overall, 5-year OS was 55%. Different OS was observed among the 3 groups: median survival not reached, 81 and 8 months, respectively (P < 0.001). Median PFS was 18 months. Both OS and PFS were significantly affected by Ki67 and metastatic spread pattern.

CONCLUSIONS

The stratification of stage IV NET patients based on metastatic patterns, alongside Ki67, predicts the clinical outcome. The extent of metastatic disease is a previously unrecognized variable, which should be considered when evaluating the results of treatments in NET patients with advanced disease.

Everolimus and sunitinib for advanced pancreatic neuroendocrine tumors: a matching-adjusted indirect comparison

Background

Everolimus and sunitinib have been approved for the treatment advanced pancreatic neuroendocrine tumors, but have not been compared to each other in a randomized trial and have not demonstrated prolonged overall survival compared to placebo. This study aimed to indirectly compare overall and progression-free among everolimus, sunitinib and placebo across separate randomized trials.

Methods

A matching adjusted indirect comparison was conducted in which individual patient data from the pivotal trial of everolimus (n = 410) were adjusted to match the inclusion criteria and average baseline characteristics reported for the pivotal trial of sunitinib (n = 171). Prior to matching, trial populations differed in baseline performance status and prior treatments. After matching, these and all other available baseline characteristics were balanced between trials.

Results

Compared to the placebo arm in the sunitinib trial, everolimus was associated with significantly prolonged overall survival (HR = 0.61, 95% CI = 0.38-0.98, p = 0.042).

Compared to sunitinib, everolimus was associated with similar progression-free (hazard ratio for death (HR) = 0.84, 95% CI = 0.46–1.53, p = 0.578) and overall survival (HR = 0.81, 95% CI = 0.49–1.31, p = 0.383).

Conclusion

After adjusting for observed cross-trial differences, everolimus treatment was associated with longer overall survival than the placebo arm in the sunitinib trial for advanced pancreatic neuroendocrine tumors.

Treatment of malignant pancreatic neuroendocrine neoplasms: middle-term (2-year) outcomes of a prospective observational multicentre study

BACKGROUND

Information on malignant pancreatic neuroendocrine neoplasms (pNENs) is mostly from retrospective studies in highly selected patients. The aim of this prospective, multicentre study was to assess treatment and outcomes of malignant pNENs in clinical practice.

PATIENTS AND METHODS

Consecutive patients with newly diagnosed, histologically-proven pNENs were included and followed-up for 2 years. Tumours were defined as malignant when nodal or distant metastases were present or invasion of extrapancreatic structures/organs was evident.

RESULTS

A total of 140 patients with malignant pNENs were included. Ninety-eight patients (70.0%) underwent a surgical resection (76 radical and 22 palliative). Other non-surgical treatments were used in 101 patients (72.1%): somatostatin analogues (n = 63), chemotherapy (n = 30), ablative treatments (n = 15) and peptide-receptor radionuclide therapy (n = 14). No relationship was observed between the 2010 WHO classification and type of treatment. A surgical resection was more often performed in incidentally detected tumours located in the pancreas body tail. Two-year progression-free survival was 63.8%: 82% after a radical resection, 44% after a palliative resection and 41% without a resection. A radical resection and Ki67 proliferative index >5% and >10% were the only significant prognostic determinants in multivariate analysis.

CONCLUSIONS

A radical resection is the cornerstone treatment of malignant pNENs and represents, together with Ki67 assessment, the most powerful prognostic factor for 2-year outcomes.

Quality of life, resource utilisation and health economics assessment in advanced neuroendocrine tumours: a systematic review

Neuroendocrine tumours (NET) are often diagnosed at an advanced stage when the prognosis is poor for patients, who often experience diminished quality of life (QoL). As new treatments for NET become available, it is important to characterise the associated outcomes, costs and QoL. A comprehensive search was performed to systematically review available data in advanced NET regarding cost of illness/resource utilisation, economic studies/health technology assessment and QoL. Four rounds of sequential review narrowed the search results to 22 relevant studies. Most focused on surgical procedures and diagnostic tools and contained limited information on the costs and consequences of medical therapies. Multiple tools are used to assess health-related QoL in NET, but few analyses have been conducted to assess the comparative impact of available treatment alternatives on QoL. Limitations include English language and the focus on advanced NET; ongoing terminology and classification changes prevented pooled statistical analyses. This systematic review suggests a lack of comparative economic and outcomes data associated with NET treatments. Further research on disease costs, resource utilisation and QoL for patients with advanced NET is warranted.

Free somatostatin receptor fraction predicts the antiproliferative effect of octreotide in a neuroendocrine tumor model: implications for dose optimization

Somatostatin receptors (SSTR) are highly expressed in well-differentiated neuroendocrine tumors (NET). Octreotide, an SSTR agonist, has been used to suppress the production of vasoactive hormones and relieve symptoms of hormone hypersecretion with functional NETs. In a clinical trial, an empiric dose of octreotide treatment prolonged time to tumor progression in patients with small bowel neuroendocrine (carcinoid) tumors, irrespective of symptom status. However, there has yet to be a dose optimization study across the patient population, and methods are currently lacking to optimize dosing of octreotide therapy on an individual basis. Multiple factors such as total tumor burden, receptor expression levels, and nontarget organ metabolism/excretion may contribute to a variation in SSTR octreotide occupancy with a given dose among different patients. In this study, we report the development of an imaging method to measure surface SSTR expression and occupancy level using the PET radiotracer (68)Ga-DOTATOC. In an animal model, SSTR occupancy by octreotide was assessed quantitatively with (68)Ga-DOTATOC PET, with the finding that increased occupancy resulted in decreased tumor proliferation rate. The results suggested that quantitative SSTR imaging during octreotide therapy has the potential to determine the fractional receptor occupancy in NETs, thereby allowing octreotide dosing to be optimized readily in individual patients. Clinical trials validating this approach are warranted.

Rapid dramatic alterations to the tumor microstructure in pancreatic cancer following irreversible electroporation ablation

AIM

NanoKnife(®) (Angiodynamics, Inc., NY, USA) or irreversible electroporation (IRE) is a newly available ablation technique to induce the formation of nanoscale pores within the cell membrane in targeted tissues. The purpose of this study was to elucidate morphological alterations following 30 min of IRE ablation in a mouse model of pancreatic cancer.

MATERIALS & METHODS

Immunohistochemistry markers were compared with diffusion-weighted MRI apparent diffusion coefficient measurements before and after IRE ablation.

RESULTS

Immunohistochemistry apoptosis index measurements were significantly higher in IRE-treated tumors than in controls. Rapid tissue alterations after 30 min of IRE ablation procedures (structural and morphological alterations along with significantly elevated apoptosis markers) were consistently observed and well correlated to apparent diffusion coefficient measurements.

DISCUSSION

This imaging assay offers the potential to serve as an in vivo biomarker for noninvasive detection of tumor response following IRE ablation.

Prognostic significance of MTOR pathway component expression in neuroendocrine tumors

PURPOSE

Clinical studies have implicated the mechanistic target of rapamycin (serine/threonine kinase; MTOR) pathway in the regulation of neuroendocrine tumor (NET) growth. We explored whether expression of MTOR pathway components has prognostic significance in NET patients.

PATIENTS AND METHODS

We evaluated immunohistochemical expression of MTOR and phospho (p) -MTOR; its downstream targets RPS6KB1, RPS6, and EIF4EBP1; and its upstream regulators, in a cohort of 195 archival neuroendocrine tumors. We correlated expression levels with clinical outcomes, after adjusting for other prognostic variables.

RESULTS

We observed anticipated correlations between expression of upstream components of the MTOR pathway and their downstream targets. Expression of PIK3CA, MTOR, or p-EIF4EBP1 was associated with high MKI67 (Ki-67) labeling index. We failed to identify clinical correlations associated with expression of the upstream regulators TSC1, TSC2, AKT, p-AKT, PDPK1, PTEN, PIK3R1, or PIK3CA. In contrast, high expression of MTOR or its activated downstream targets p-RPS6KB1, p-RPS6, or p-EIF4EBP1 was associated with adverse clinical outcomes.

CONCLUSION

Our observations suggest that expression of MTOR or its downstream targets may be adverse prognostic factors in neuroendocrine tumors.

A pictoral review on somatostatin receptor scintigraphy in neuroendocrine tumors: The role of multimodality imaging with SRS and GLUT receptor imaging with FDG PET-CT

Somatostatin receptor scintigraphy is considered as a comprehensive imaging modality for many neuroendocrine tumors. Multiple radiotracers using combinations of gamma or positron emitting radionuclides and tracers are now available. Newer radiopharmaceuticals using ^99mTc labeled with TOC, TATE, NOC are good alternatives to the 68 - Gallium radiotracers where the PET facility is not available. The pictoral depicts the role of SRS using 99m TC – HYNIC –TOC radiotracers in staging and treatment planning of NETs. Characterization of the tumor biology using combined SRS and FDG PET/CT is also demonstrated with a proposed categorization method. The emerging role of SRS in tailored targeted radionuclide therapy is outlined in brief.

Safety, tolerability, pharmacokinetics, and pharmacodynamics of a long-acting release (LAR) formulation of pasireotide (SOM230) in patients with gastroenteropancreatic neuroendocrine tumors: results from a randomized, multicenter, open-label, phase I study

PURPOSE

Pasireotide (SOM230), a novel multireceptor ligand somatostatin analog (SSA), binds with high affinity to four of the five somatostatin receptor subtypes (sst1-3, 5). This study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics profiles of pasireotide long-acting release (LAR) formulation in patients with advanced gastroenteropancreatic neuroendocrine tumor (GEP NET) refractory to other SSAs.

METHODS

In this randomized, multicenter, open-label, phase II study, patients with biopsy-proven primary or metastatic GEP NET refractory to available SSAs were randomly assigned 1:1:1 to receive pasireotide LAR by deep intragluteal injection at a dose of 20, 40, or 60 mg once every 28 days for 3 months.

RESULTS

Forty-two patients received pasireotide LAR. Adverse events were reported by 34 (81 %) patients, with the most frequently reported including diarrhea, fatigue, abdominal pain, and nausea. Mean fasting glucose levels were increased compared with baseline at all points throughout the study. After the third injection of pasireotide LAR, the median trough plasma concentrations on day 84 were 4.82, 12.0, and 19.7 ng/mL in the 20-, 40-, and 60-mg treatment groups, respectively. Drug accumulation was limited for each dose based on the increase in trough concentrations after the first to third injections (accumulation ratios were approximately 1 from all dose levels).

CONCLUSIONS

This study demonstrated that a new, once-monthly, intramuscular LAR formulation of pasireotide was well tolerated in patients with advanced GEP NET. Steady state levels of plasma pasireotide were achieved after three injections.

A multi-institutional, phase II open-label study of ganitumab (AMG 479) in advanced carcinoid and pancreatic neuroendocrine tumors

The IGF pathway has been implicated in the regulation of neuroendocrine tumor (NET) growth, and preliminary studies suggested that ganitumab (AMG 479), a human MAB against IGF1R, may have antitumor activity in this setting. We performed a two-cohort phase II study of ganitumab in patients with metastatic progressive carcinoid or pancreatic NETs (pNETs). This open-label study enrolled patients (≥18 years) with metastatic low- and intermediate-grade carcinoid or pNETs. Inclusion criteria included evidence of progressive disease (by Response Evaluation Criteria in Solid Tumors (RECIST)) within 12 months of enrollment, ECOG PS 0-2, and fasting blood sugar <160  mg/dl. Prior treatments were allowed and concurrent somatostatin analog therapy was permitted. The primary endpoint was objective response. Secondary endpoints included overall survival (OS), progression-free survival (PFS), and safety. Sixty patients (30 carcinoid and 30 pNETs) were treated with ganitumab 18  mg/kg every 3 weeks, among whom 54 patients were evaluable for survival and 53 patients for response. There were no objective responders by RECIST. The median PFS duration was 6.3 months (95% CI, 4.2-12.6) for the entire cohort; 10.5 months for carcinoid patients, and 4.2 months for pNET patients. The OS rate at 12 months was 66% (95% CI, 52-77%) for the entire cohort. The median OS has not been reached. Grade 3/4 AEs were rare and consisted of hyperglycemia (4%), neutropenia (4%), thrombocytopenia (4%), and infusion reaction (1%). Although well tolerated, treatment with single-agent ganitumab failed to result in significant tumor responses among patients with metastatic well-differentiated carcinoid or pNET.

The identification of gut neuroendocrine tumor disease by multiple synchronous transcript analysis in blood

Gastroenteropancreatic (GEP) neuroendocrine neoplasms (NENs) are increasing in both incidence and prevalence. A delay in correct diagnosis is common for these lesions. This reflects the absence of specific blood biomarkers to detect NENs. Measurement of the neuroendocrine secretory peptide Chromogranin A (CgA) is used, but is a single value, is non-specific and assay data are highly variable. To facilitate tumor detection, we developed a multi-transcript molecular signature for PCR-based blood analysis. NEN transcripts were identified by computational analysis of 3 microarray datasets: NEN tissue (n = 15), NEN peripheral blood (n = 7), and adenocarcinoma (n = 363 tumors). The candidate gene signature was examined in 130 blood samples (NENs: n = 63) and validated in two independent sets (Set 1 [n = 115, NENs: n = 72]; Set 2 [n = 120, NENs: n = 58]). Comparison with CgA (ELISA) was undertaken in 176 samples (NENs: n = 81). 51 significantly elevated transcript markers were identified. Gene-based classifiers detected NENs in independent sets with high sensitivity (85–98%), specificity (93–97%), PPV (95–96%) and NPV (87–98%). The AUC for the NEN gene-based classifiers was 0.95–0.98 compared to 0.64 for CgA (Z-statistic 6.97–11.42, p<0.0001). Overall, the gene-based classifier was significantly (χ² = 12.3, p<0.0005) more accurate than CgA. In a sub-analysis, pancreatic NENs and gastrointestinal NENs could be identified with similar efficacy (79–88% sensitivity, 94% specificity), as could metastases (85%). In patients with low CgA, 91% exhibited elevated transcript markers. A panel of 51 marker genes differentiates NENs from controls with a high PPV and NPV (>90%), identifies pancreatic and gastrointestinal NENs with similar efficacy, and confirms GEP-NENs when CgA levels are low. The panel is significantly more accurate than the CgA assay. This reflects its utility to identify multiple diverse biological components of NENs. Application of this sensitive and specific PCR-based blood test to NENs will allow accurate detection of disease, and potentially define disease progress enabling monitoring of treatment efficacy.

Targeted therapies in neuroendocrine tumors (NET): clinical trial challenges and lessons learned

In the past 3 years, we have witnessed the completion of four randomized phase III studies in neuroendocrine tumors and the approval of two new drugs, everolimus and sunitinib, for the treatment of patients with well-differentiated pancreatic neuroendocrine tumors. These studies demonstrate a shift from case series and single-arm studies toward prospective, randomized controlled clinical trials and evidence-based therapy in the neuroendocrine tumor field. However, the clinical development of these agents also highlights the potential challenges awaiting other new drugs in this area. Herein, we discuss the strengths and weaknesses of the most recent phase II and phase III neuroendocrine tumor studies and discuss how limitations inherent in current trial design can lead to potential pitfalls. We also discuss how trial design can be improved, with the hope of increasing the number of drugs successfully developed to treat patients with neuroendocrine tumors.

Survival outcomes and prognostic factors of transcatheter arterial chemoembolization for hepatic neuroendocrine metastases

PURPOSE

To report survival outcomes in patients with neuroendocrine tumor (NET) with hepatic metastasis who were treated by transcatheter arterial chemoembolization and determine prognostic factors that affect clinical outcome.

MATERIALS AND METHODS

Patients with NET with hepatic metastasis who underwent chemoembolization between April 2002 and July 2011 were included in this single-center, retrospective study. Progression-free survival (PFS) and overall survival (OS) were calculated by Kaplan-Meier method. The influence of possible prognostic factors on survival was analyzed by log-rank method and multivariate Cox proportional-hazards method.

RESULTS

Forty-six patients with hepatic metastasis from nonpancreatic NETs (npNETs; n = 24) or pancreatic NETs (pNETs; n = 22) were included. The median PFS and OS times for the entire group were 16.2 and 38.6 months, respectively, and response rate was 58.1%. Patients with npNET had a similar PFS (17.4 mo vs 15.3 mo) and longer OS (55.0 mo vs 27.6 mo) compared with those with pNET, but there were no significant differences in PFS and OS between groups (P = .398 and P = .375, respectively). By univariate analysis, enterobiliary communication, hepatic tumor burden, and extrahepatic metastasis before the first chemoembolization were significant prognostic factors for poor OS (P = .001, P = .010, and P<.0001, respectively). By multivariate analysis, the same prognostic factors were significant and had relative risks of 4.63, 2.71, and 5.09, respectively.

CONCLUSIONS

Transcatheter arterial chemoembolization is an effective treatment modality for hepatic metastasis from NETs, with a median OS of 38.6 months and response rate of 58%. Enterobiliary communication, large hepatic tumor burden, and extrahepatic metastasis were significant risk factors for poor survival outcome.

Systemic therapeutic options for carcinoid

"Carcinoids" are mostly slow-growing neuroendocrine neoplasms (NENs) with low proliferative activity. A wide range of therapeutic options with variable efficacy exist, including locoregional ablative strategies. Thereafter, some patients may not require medical therapy for years depending on the rate of progression or recurrence. However, the majority of patients require systemic treatment and therein lies the dilemma, since no antiproliferative agent is currently approved for carcinoids. Somatostatin analogs (SSAs), and to a lesser extent interferon-alpha, are standard therapy for carcinoids associated with the carcinoid syndrome. These drugs have some antiproliferative efficacy. SSAs rarely lead to tumor remission but may modestly prolong time to tumor progression. Chemotherapy is of limited value in carcinoids with low proliferation indices but may be useful in higher grade tumors. Peptide receptor-targeted radionuclide therapy may be of benefit and is mostly used after medical therapies fail. However, it is considered an investigational modality. More recently, targeted drugs such as mammalian target of rapamycin (mTOR) inhibitors and anti-angiogenics have been investigated. Objective remissions are rare. Their value remains to be rigorously elucidated. Increased efficacy requires a better understanding of the underlying tumor biology and identification of molecular pathological criteria to allow appropriate preselection of candidates for targeted therapies.

Islet-1 is a sensitive but not entirely specific marker for pancreatic neuroendocrine neoplasms and their metastases

Islet-1 (Isl1) is a transcription factor involved in the embryogenesis of islets of Langerhans. Immunohistochemically, Isl1 is a sensitive lineage-specific marker for pancreatic neuroendocrine neoplasms (NENs) and their metastases. Its specificity has not been documented, nor have large numbers of NENs from other parts of the gut or other organs been studied. We examined Isl1 expression in 203 primary NENs (gastroenteropancreatic, lung, breast, and ovarian neoplasms) and 40 hepatic NEN metastases (enteropancreatic and lung neoplasms) from known primaries. The correlation between Isl1 and CDX2 expression was studied using a tissue microarray containing 46 pancreatic NENs. Immunostaining for Isl1 and CDX2 was also performed in selected NENs from other sites. Isl1 was positive in 90% of pancreatic, 89% of duodenal, 100% of rectal, 38% of colonic, 14% of appendiceal, and 6% of ileal primaries. Isl1 was negative in all other NENs. Among metastatic neoplasms, 76% of pancreatic and 2 of 2 rectal NEN metastases were Isl1 positive, whereas all other tested metastases were negative. The overall sensitivity and specificity of Isl1 in identifying primary pancreatic NENs was 88% and 80%, respectively. Thirty-six of 46 pancreatic NENs in the tissue microarray were Isl1 positive; 4 were Isl1 negative but CDX2 positive. Our findings confirm that Isl1 is a sensitive marker of pancreatic origin in cases of metastatic NEN. However, Isl1 does not distinguish pancreatic NEN from duodenal and colorectal NEN, even when used in association with CDX2.

Clinical presentation, recurrence, and survival in patients with neuroendocrine tumors: results from a prospective institutional database

The rarity of neuroendocrine tumors (NET) has contributed to a paucity of large epidemiologic studies of patients with this condition. We characterized presenting symptoms and clinical outcomes in a prospective database of over 900 patients with NET. We used data from patient questionnaires and the medical record to characterize presenting symptoms, disease-free survival (DFS), and overall survival (OS). The majority of patients in this database had gastroenteropancreatic NET. The median duration of patient-reported symptoms before diagnosis was 3.4 months; 19.5% reported durations from 1 to 5 years, 2.5% from 5 to 10 years, and 2% >10 years. The median DFS among patients with resected small bowel NET or pancreatic NET (panNET) was 5.8 and 4.1 years respectively. After correcting for left truncation bias, the median OS was 7.9 years for advanced small bowel NET and 3.9 years for advanced panNET. Chromogranin A (CGA) above twice the upper limit of normal was associated with shorter survival times (hazard ratios 2.8 (1.9, 4.0) P<0.001) in patients with metastatic disease, regardless of tumor subtype. Our data suggest that while most NET patients are diagnosed soon after symptom onset, prolonged symptom duration before diagnosis is a prominent feature of this disease. Though limited to observations from a large referral center, our observations confirm the prognostic value of CGA and suggest that median survival durations may be shorter than that reported in other institutional databases.

Peptide receptor radionuclide therapy with (90)Y-DOTATATE/(90)Y-DOTATOC in patients with progressive metastatic neuroendocrine tumours: assessment of response, survival and toxicity

Background:

Peptide receptor radionuclide therapy (PRRT) is an established treatment for patients with metastatic neuroendocrine tumours (NETs), although which factors are associated with an improved overall survival (OS) remains unclear. The primary aim of this study is to determine to what extent a radiological response to ⁹⁰Y-DOTATOC/⁹⁰Y-DOTATATE PRRT is associated with an improved OS. The association of biochemical and clinical response to OS were assessed as secondary outcome measures.

Methods:

A retrospective analysis was conducted on 57 patients: radiological response was classified using RECIST criteria, biochemical response was classified using WHO criteria and clinical response was assessed subjectively. Responses were recorded as positive response (PR), stable disease (SD) or progressive disease (PD), and survival analysed.

Results:

Radiological response was achieved in 71.5% (24.5% PR, 47% SD) and was associated with a greater OS (51 and 56 months, respectively), compared with PD (18 months). A biochemical or clinical response post PRRT were not associated with a statistically significant improvement in OS. However, when combined with radiological response a survival benefit was observed according to the number of outcomes (radiological, biochemical, clinical), in which a response was observed. Mild haematological toxicity was common, renal toxicity was rare.

Conclusion:

In patients with progressive metastatic NETs receiving ⁹⁰Y-DOTATOC/⁹⁰Y-DOTATATE PRRT, a radiological response with either a PR or a SD post therapy confers a significant OS benefit.

International practice patterns and resource utilization in the treatment of neuroendocrine tumors

OBJECTIVES

This study compared resource use and practice patterns in patients with advanced neuroendocrine tumors (NETs) on disease progression, across countries, and by tumor type.

METHODS

Physicians in the United States, United Kingdom, Germany, France, Brazil, and Italy completed data extraction forms to extract chart data of patients with NET relating to health care resource utilization and treatment practice. Data were assessed in a cross-sectional manner, by country, and by NET subtype. Univariate and multivariate analyses were performed to compare categories of resource use by disease progression status.

RESULTS

A total of 197 physicians provided data on 394 patients. Overall resource utilization was high across tumor types, countries, and progression. Nearly half of all patients received chemotherapy (49%); moreover, high rates of hospitalization (65%), surgery (47%), and use of somatostatin analog (77%) were observed, with lower rates of peptide receptor radionuclide therapy (10%) and targeted therapies (6%). These patterns were consistent across gastrointestinal tract/lung NET and pancreatic NET. However, a certain variation in resource utilization was observed across countries. Disease progression was associated with increasing utilization of chemotherapy, hospitalization, and targeted therapy.

CONCLUSIONS

Advanced NET is associated with significant resource use across subtypes and countries, and resource utilization is likely to increase on disease progression. There remains an unmet need for therapeutic options after disease progression.

Treatment with the radiolabelled somatostatin analog Lu-DOTATATE for advanced pancreatic neuroendocrine tumors

BACKGROUND

We evaluated the activity and safety profile of (177)Lu-DOTATATE peptide receptor radionuclide therapy (Lu-PRRT) in patients with advanced G1-G2 pancreatic neuroendocrine tumors.

PATIENTS AND METHODS

Fifty-two consecutive patients were treated at two different therapeutic dosages of 18.5 or 27.8 GBq in five cycles, according to the patient's kidney function and bone marrow reserve, which are known to be the critical organs in PRRT.

RESULTS

Twenty-six patients received a mean full dosage (FD) of 25.5 GBq (range 20.7-27.8) and 26 a mean reduced dosage (RD) of 17.8 GBq (range 11.1-19.9). Both therapeutic dosages resulted in antitumor activity (disease control rate in the entire case series 81%), with 12% complete response, 27% partial response and 46% stable disease in the FD group, whereas we observed 4% complete response, 15% partial response and 58% stable disease in the RD group. Median progression-free survival was not reached in the FD group and was 20 months in the RD group. No major acute or delayed hematological toxicity occurred.

CONCLUSION

(177)Lu-DOTATATE peptide receptor radionuclide therapy showed antitumor activity in advanced pancreatic neuroendocrine tumors even at a reduced total activity of 18.5 GBq. However, progression-free survival was significantly longer (p = 0.05) after a total activity of 27.8 GBq, which can thus be considered the recommended dosage in eligible patients.

Translation of molecular pathways into clinical trials of neuroendocrine tumors

Current treatment options for neuroendocrine tumors (NET) include somatostatin analogs, interferon-α, peptide receptor-targeted therapy and cytotoxic chemotherapy. Most patients undergo sequential therapies since these drugs are active only in subpopulations of patients and for a limited period of time. There is a need for novel drugs that are capable of amelioration of symptomatology (syndromic control) and/or tumor growth control. A number of diverse signaling pathways are involved in the pathogenesis of NET and tumor growth, thus many potential targets are available for drug targeting. Targeted therapies therefore represent an appropriate developmental therapeutic strategy given the multiplicity of potential targets in NET. These include but are not limited to: inhibitory or activating G protein-coupled receptors, receptor tyrosine kinases, ligands, and intracellular targets such as the mammalian target of rapamycin (mTOR). Numerous drugs that utilize single or multiple targets are currently in clinical development. Recently, two target-directed agents, the multiple tyrosine kinase inhibitor sunitinib and the mTOR inhibitor everolimus, have been approved for the treatment of progressive pancreatic NET. This review provides a broad overview of established and potential molecular targets in NET, summarizes data from phase II and III clinical trials with targeted drugs and outlines future therapeutic directions.

Selecting patients for cytotoxic therapies in gastroenteropancreatic neuroendocrine tumours

Gastroenteropancreatic neuroendocrine tumours (GEP-NET) have heterogenic clinical presentations. The majority of GEP-NET tumours have an indolent behaviour, but patients will eventually develop symptoms of tumour progression or hormone secretion that may require systemic medical interventions. Cytotoxic chemotherapy has been tested in GEP-NETs since the 80s, but treatment recommendations are controversial in many instances. Patient selection is mandatory for optimal use of chemotherapy. Important prognostic factors such as primary tumour site, tumour differentiation, tumour staging and proliferation index have been identified and validated in retrospective and prospective series. The combination of those factors and the natural history of GEP-NET provide valuable information with respect to treatment planning. In this report we provide treatment recommendations to improve systemic therapy in patients with advanced GEP-NETs based on a comprehensive review of the literature.

The somatostatin analogue octreotide inhibits growth of small intestine neuroendocrine tumour cells

Octreotide is a widely used synthetic somatostatin analogue that significantly improves the management of neuroendocrine tumours (NETs). Octreotide acts through somatostatin receptors (SSTRs). However, the molecular mechanisms leading to successful disease control or symptom management, especially when SSTRs levels are low, are largely unknown. We provide novel insights into how octreotide controls NET cells. CNDT2.5 cells were treated from 1 day up to 16 months with octreotide and then were profiled using Affymetrix microarray analysis. Quantitative real-time PCR and western blot analyses were used to validate microarray profiling in silico data. WST-1 cell proliferation assay was applied to evaluate cell growth of CNDT2.5 cells in the presence or absence of 1 µM octreotide at different time points. Moreover, laser capture microdissected tumour cells and paraffin embedded tissue slides from SI-NETs at different stages of disease were used to identify transcriptional and translational expression. Microarrays analyses did not reveal relevant changes in SSTR expression levels. Unexpectedly, six novel genes were found to be upregulated by octreotide: annexin A1 (ANXA1), rho GTPase-activating protein 18 (ARHGAP18), epithelial membrane protein 1 (EMP1), growth/differentiation factor 15 (GDF15), TGF-beta type II receptor (TGFBR2) and tumour necrosis factor (ligand) superfamily member 15 (TNFSF15). Furthermore, these novel genes were expressed in tumour tissues at transcript and protein levels. We suggest that octreotide may use a potential novel framework to exert its beneficial effect as a drug and to convey its action on neuroendocrine cells. Thus, six novel genes may regulate cell growth and differentiation in normal and tumour neuroendocrine cells and have a role in a novel octreotide mechanism system.

Phase I-II study of radiopeptide 177Lu-octreotate in combination with capecitabine and temozolomide in advanced low-grade neuroendocrine tumors

Abstract We conducted a phase I-II clinical trial to assess the safety and efficacy of combining lutetium-177 ((177)Lu)-octreotate with capecitabine and temozolomide in treating advanced low-grade neuroendocrine tumors (NETs). All 35 patients received fixed activities of 7.8 GBq (177)Lu-octreotate each 8 weeks, with 14 days of capecitabine 1500 mg/m(2) for 4 cycles. In phase I, successive cohorts of patients received escalating doses of temozolomide in groupings of 100, 150, and 200 mg/m(2) in the last 5 days of each capecitabine cycle. In phase II, patients were treated with 200 mg/m(2) temozolomide. Treatment was well tolerated in all dosage groups. No dose-limiting grade 2, 3, or 4 toxicities were seen in cohorts 1 (100 mg/m(2)) or 2 (150 mg/m(2)). Twenty-eight patients completed treatment at the 200 mg/m(2) temozolomide level. Adverse events were mild to moderate. The commonest toxicities were transient nausea grade 2 (18%), grade 3 (3%), thrombocytopenia grade 2 (24%), and neutropenia grade 3 (6%). There were no grade 4 events. Thirty-four patients were evaluable for tumor response. Overall, complete response (CR) was achieved in 15% (95% CI 3-27); partial response (PR), in 38% (95% CI 22-55); stable disease (SD), in 38% (95% CI 22-55); and 3 patients failed to respond to treatment. Median progression free survival (PFS) was 31 months (95% CI 21-33), and median overall survival (OS) has not been reached with 90% surviving at 24 months follow-up (range 21-30). Overall objective response rate (ORR) in patients with gastroenteropancreatic NETs showed CR 16% (95% CI 3-28), PR 41% (95% CI 24-58), SD 37% (95% CI 21-54), and PD 6% (95% CI 0-15). Response rates were higher in patients with gastropancreatic NETs than in those with bowel primaries (enteric-NETs); CR 18% versus 13%, PR 64% versus 13%, SD 12% versus 67%. (177)Lu-octreotate, in combination with capecitabine and temozolomide, is well tolerated in patients with advanced low-grade NETs, and shows substantial tumor control rates.

(64)Cu-NODAGA-c(RGDyK) Is a Promising New Angiogenesis PET Tracer: Correlation between Tumor Uptake and Integrin α(V)β(3) Expression in Human Neuroendocrine Tumor Xenografts

Purpose. The purpose of this paper is to evaluate a new PET tracer ⁶⁴Cu-NODAGA-c(RGDyK) for imaging of tumor angiogenesis using gene expression of angiogenesis markers as reference and to estimate radiation dosimetry for humans. Procedures. Nude mice with human neuroendocrine tumor xenografts (H727) were administered ⁶⁴Cu-NODAGA-c(RGDyK) i.v. for study of biodistribution as well as for dynamic PET. Gene expression of angiogenesis markers integrin α_V, integrin β₃, and VEGF-A were analyzed using QPCR and correlated to the tracer uptake in the tumors (%ID/g). From biodistribution data human radiation-absorbed doses were estimated using OLINDA/EXM. Results. Tumor uptake was 1.2%ID/g with strong correlations between gene expression and tracer uptake, for integrin α_V  R = 0.76, integrin β₃  R = 0.75 and VEGF-A R = 0.81 (all P < 0.05). The whole body effective dose for humans was estimated to be 0.038 and 0.029 mSv/MBq for females and males, respectively, with highest absorbed dose in bladder wall. Conclusion. ⁶⁴Cu-NODAGA-c(RGDyK) is a promising new angiogenesis PET tracer with potential for human use.

Molecular pathology of pancreatic neuroendocrine tumors

Pancreatic endocrine tumors (PETs) are rare neoplasms which account for 1% to 2% of all pancreatic malignancies. The diagnostic, grading and prognostic criteria for PETs have been controversial in surgical pathology and clinical medicine. The newly updated 2010 WHO classification introduced in clinical practice will give more insight into genetic and molecular changes related to PET subtypes. These neoplasms can be graded into 1 of 3 tiers, based on histologic characteristics in likeness to epithelial neuroendocrine tumors in other anatomic sites. Most PETs are sporadic, however, some of them, may occur as part of familial tumors (inherited syndromes) such as multiple endocrine neoplasia type 1 (MEN1 syndrome), von Hippel-Lindau disease (VHL), neurofibromatosis type 1 (NF-1), and tuberous sclerosis (TSC). In sporadic endocrine pancreatic tumors, losses of chromosome 1 and 11q as well as gain on 9q appear to be early events in the development of pancreatic tumors. Multiple genetic defects may accumulate with time and result in pancreatic neuroendocrine tumor progression and malignancy. Although PETs may be similar or identical in histologic appearance to neuroendocrine tumors of the gastrointestinal tract, differences in their underlying biology and likely differences in response to therapeutic agents suggest that they should be treated and investigated as a distinct entity. The correlation of PI3K/Akt/mTOR pathway in the pathogenesis of PETs has been reported, and clinical trials data of mTOR inhibitors is promising.

The expanding role of somatostatin analogs in the management of neuroendocrine tumors

BACKGROUND

Neuroendocrine tumors (NETs) are neoplasms arising most often in the GI tract, pancreas, or lung. Diagnosis of NETs is often delayed until the disease is advanced, because of the variable and nonspecific nature of the initial symptoms. Surgical resection for cure is therefore not an option for most patients.

METHODS

Somatostatin analogues represent the cornerstone of therapy for patients with NETs. This article reviews the important role that somatostatin analogues continue to play in the treatment of patients with NETs.

RESULTS

Octreotide was the first somatostatin analogue to be developed; more than 30 years of data have accumulated demonstrating its efficacy and safety. Lanreotide is another somatostatin analogue in clinical use, and pasireotide is a promising somatostatin analogue in development. Newer long-acting depot formulations are now available offering once-monthly administration. Although octreotide was initially developed for symptom control, recent results indicate that it also has an antiproliferative effect, significantly increasing time to progression in patients with midgut NETs. Combinations of octreotide with other targeted therapies may further improve patient outcomes. Findings in recent studies of the combination of octreotide and the mTOR inhibitor everolimus are encouraging. The combinations of octreotide with other agents (eg, interferon-α, bevacizumab, cetuximab, AMG-706, and sunitinib) are being investigated.

CONCLUSIONS

Somatostatin analogues have been used to treat the symptoms of NETs for decades and also have an antineoplastic effect, markedly prolonging progression-free survival. Somatostatin analogues are likely to remain the cornerstone of treatment for most patients with advanced NETs. Promising new combination therapies are undergoing clinical investigation.

Therapy of metastatic pancreatic neuroendocrine tumors (pNETs): recent insights and advances

Neuroendocrine tumors (NETs) [carcinoids, pancreatic neuroendocrine tumors (pNETs)] are becoming an increasing clinical problem because not only are they increasing in frequency, but they can frequently present with advanced disease that requires diagnostic and treatment approaches different from those used in the neoplasms that most physicians are used to seeing and treating. In the past few years there have been numerous advances in all aspects of NETs including: an understanding of their unique pathogenesis; specific classification systems developed which have prognostic value; novel methods of tumor localization developed; and novel treatment approaches described. In patients with advanced metastatic disease these include the use of newer chemotherapeutic approaches, an increased understanding of the role of surgery and cytoreductive methods, the development of methods for targeted delivery of cytotoxic agents, and the development of targeted medical therapies (everolimus, sunitinib) based on an increased understanding of the disease biology. Although pNETs and gastrointestinal NETs share many features, recent studies show they differ in pathogenesis and in many aspects of diagnosis and treatment, including their responsiveness to different therapies. Because of limited space, this review will be limited to the advances made in the management and treatment of patients with advanced metastatic pNETs over the past 5 years.

The current management of pancreatic neuroendocrine tumors

PanNETs constitute a rare and heterogeneous group of pancreatic neoplasms whose overall prognosis is better than the more common pancreatic adenocarcinoma. Although surgery is the only treatment that provides a cure, many adjuvant therapies have been explored with some new, exciting, targeted therapies just approved for PanNETs. With growing interest in this type of neoplasm, an increasing number of clinical trials and natural history studies should shed light on the best management for these patients.

Succinate dehydrogenase B subunit immunohistochemical expression predicts aggressiveness in well differentiated neuroendocrine tumors of the ileum

Immunohistochemical loss of the succinate dehydrogenase subunit B (SDHB) has recently been reported as a surrogate biomarker of malignancy in sporadic and familial pheocromocytomas and paragangliomas through the activation of hypoxia pathways. However, data on the prevalence and the clinical implications of SDHB immunoreactivity in ileal neuroendocrine tumors are still lacking. Thirty-one consecutive, advanced primary midgut neuroendocrine tumors and related lymph node or liver metastases from 24 males and seven females were immunohistochemically assessed for SDHB. All patients were G1 tumors (Ki-67 labeling index ≤2%). SDHB immunohistochemistry results were expressed as immunostaining intensity and scored as low or strong according to the internal control represented by normal intestinal cells. Strong positivity for SDHB, with granular cytoplasmatic reactivity, was found in 77% of primary tumors (T), whilst low SDHB expression was detected in 90% of metastases (M). The combined analysis (T+M) confirmed the loss of SDHB expression in 82% of metastases compared to 18% of primary tumors. SDHB expression was inversely correlated with Ki-67 labeling index, which accounted for 1.54% in metastastic sites and 0.7% in primary tumors. A correlation between SDHB expression loss, increased Ki-67 labeling index and biological aggressiveness was shown in advanced midgut neuroendocrine tumors, suggesting a role of tumor suppressor gene.

Neuroendocrine tumors of the digestive tract: impact of new classifications and new agents on therapeutic approaches

PURPOSE OF REVIEW

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) constitute a diverse group of neoplasms arising from the diffuse neuroendocrine cell system. During the last 2 years a new classification system, the WHO 2010, has come into clinical practice together with Tumor Nodes Metastases (TNM) staging and grading systems, developed by the European Neuroendocrine Tumor Society/American Joint Cancer Committee. At the same time new targeted agents have been developed for treatment of GEP-NETs and it is important discuss these new agents in relation to the classification and staging system.

RECENT FINDINGS

The current article is reviewing the most important clinical trials of targeting agents within the field of neuroendocrine tumors. Tyrosine kinase inhibitors as well as PI3 kinase mTOR inhibitors have been applied in the treatment of neuroendocrine tumors.

SUMMARY

Sunitinib and everolimus have recently been registered for treatment of pancreatic neuroendocrine tumors worldwide. The role of these new targeted agents in the treatment algorithm of neuroendocrine tumors will be discussed. A large number of phase I and phase II trials have been performed in GEP-NETs with rather limited results and no significant impact on the clinical management of patients with GEP-NETs. However, there are two phase III trials that have completely changed the treatment landscape for pancreatic neuroendocrine tumors, e.g., sunitinib and everolimus demonstrating an increased progression free survival of 11 vs. 5 months for the placebo group.

Radiolabeled somatostatin analogues therapy in advanced neuroendocrine tumors: a single centre experience

The aim of this study was to assess the efficacy of PRRT in patients with advanced neuroendocrine tumors (NETs). Patients and Methods. From January 2007 to August 2011, we enrolled 65 patients (m/f 38/27; mean age 65 years, range 33–83) with advanced NETs having enhanced SSTR expression, treated with PRRT. The enhanced expression of SSTR was assessed using ⁶⁸Ga-DOTATOC/DOTATATE PET/CT. Among all the enrolled patients, 6 of them were excluded from the present analysis since they voluntarily interrupted treatment. Mean activity/cycle of 2.6 GBq (⁹⁰Y-DOTATOC/DOTATATE) or 6.0 GBq (¹⁷⁷Lu-DOTATOC/DOTATATE) was administrated intravenously (max 9 cycles). Results. Complete response (CR) was found in 1/59 (2%) patients, partial remission (PR) in 24/59 (40.5%) patients, stable disease (SD) in 24/59 (40.5%), and progression (PD) in 10/59 (17%) patients. The overall tumor response rate (CR + PR) was 42.5%. In 40.5% of patients, the disease could be stabilized. Overall, 49 out of 59 patients had no tumor progression (83%). Twelve patients out of 59 (20%) had grade 2-3 hematological side effects including anemia, thrombocytopenia, and leukopenia. Long-term nephrotoxicity was observed in 3 patients (2 moderate, 1 severe). Conclusions. PRRT is a promising perspective for patients with advanced NETs.

A rationale for multidisciplinary care in treating neuroendocrine tumours

PURPOSE OF REVIEW

Disease heterogeneity and multisystem complications represent challenges to the diagnosis and management of neuroendocrine tumours (NET), with the disease often remaining undiagnosed for years after initial presentation. The purpose of this review is to assess the limitations of traditional care models and review the potential benefits of the multidisciplinary team approach in cancer treatment and to explore the potential usefulness of the multidisciplinary team approach for patients with NET.

RECENT FINDINGS

This article outlines important considerations for the multidisciplinary management of NET, offers a model for team structure and function and identifies skill sets of members that may augment patient care. We believe a multidisciplinary team should include three to four clinicians with extensive NET experience. A coordinating physician plays a crucial role by facilitating team cohesiveness and maintaining constant patient contact throughout the course of treatment. Our model emphasizes collaboration between members of the core team and can be extended to include interactions with community healthcare professionals and others.

SUMMARY

A multidisciplinary approach offers the best prospect for improving clinical outcomes and understanding the natural history of NET.

¹¹¹In-DTPA⁰-octreotide (Octreoscan), ¹³¹I-MIBG and other agents for radionuclide therapy of NETs

This paper is a critical review of the literature on NET radionuclide therapy with (111)In-DTPA(0)-octreotide (Octreoscan) and (131)I-MIBG, focusing on efficacy and toxicity. Some potential future applications and new candidate therapeutic agents are also mentioned. Octreoscan has been a pioneering agent for somatostatin receptor radionuclide therapy. It has achieved symptomatic responses and disease stabilization, but it is now outperformed by the corresponding β-emitter agents (177)Lu-DOTATATE and (90)Y-DOTATOC. (131)I-MIBG is the radionuclide therapy of choice for inoperable or metastatic phaeochromocytomas/paragangliomas, which avidly concentrate this tracer via the noradrenaline transporter. Symptomatic, biochemical and tumour morphological response rates of 50-89%, 45-74% and 27-47%, respectively, have been reported. (131)I-MIBG is a second-line radiopharmaceutical for treatment of enterochromaffin carcinoids, mainly offering the benefit of amelioration of hormone-induced symptoms. High specific activity, non-carrier-added (131)I-MIBG and meta-astato((211)At)-benzylguanidine (MABG) are tracers with potential for enhanced therapeutic efficacy, yet their integration into clinical practice awaits further exploration. Amongst other promising agents, radiolabelled exendin analogues show potential for imaging and possibly therapy of insulinomas, while preclinical studies are currently evaluating DOTA peptides targeting the CCK-2/gastrin receptors that are overexpressed by medullary thyroid carcinoma cells.

Neuroendocrine pancreatic tumors: guidelines for management and update

Pancreatic neuroendocrine tumors (PanNETs) are a diverse group of rare neoplasms. Commonly referred to as islet cell tumors, PanNETs are classified as functional or nonfunctional depending on their production of specific pancreatic endocrine hormones (e.g. insulin, gastrin, glucagon, and others) and association with the resultant clinical syndromes. While most PanNETs are sporadic, syndromic patients, in particular those with multiple endocrine neoplasia type 1 (MEN-1) and von Hippel Lindau (VHL), are at increased risk of developing these tumors. Recent investigations of patients with sporadic and syndromic PanNETs have elucidated critical pathways in tumor development, such as mammalian target of rapamycin (mTOR) signaling and its downstream growth factors such as vascular endothelial growth factor (VEGF). Prognosis ranges from favorable for localized, low-grade neoplasms to poor for advanced, high-grade tumors. Regardless of the stage at presentation, surgery is the first-line therapy for patients with disease amenable to surgical resection. We favor formal pancreatectomy with conventional lymph node sampling for the vast majority of patients, either through open or laparoscopic techniques. Those with insulinomas, however, may be candidates for enucleation. Cytoreductive surgery is also recommended for patients with locoregional recurrences or hepatic metastases. Regional adjuvants such as radiofrequency ablation (RFA), transarterial chemoembolization (TACE), and others are often employed in an attempt to palliate symptoms and prolong survival. Unfortunately, cytotoxic chemotherapy has been largely ineffective in treating patients with PanNETs. The somatostatin analogue octreotide, however, has been effective in palliating symptoms and slowing the progression of disease. Other promising systemic agents, including sunitinib and everolimus, have targeted critical PanNET signaling pathways. In summary, surgery remains the principal therapeutic strategy for patients with PanNETs, but continued research may identify more robust systemic therapies for those with advanced disease.

Value of Islet 1 and PAX8 in identifying metastatic neuroendocrine tumors of pancreatic origin

Neuroendocrine tumors can present as liver metastases before discovery of the primary tumor. Islet 1 and PAX8 have recently been proposed as markers for neuroendocrine tumors of pancreatic origin. In this study, we compared the utility of Islet 1 and PAX8 in distinguishing pancreatic neuroendocrine tumors from neuroendocrine tumors of other sites and determined the usefulness of an immunohistochemical panel, including TTF1, CDX2, Islet 1 and/or PAX8, in identifying metastatic pancreatic neuroendocrine tumors. A total of 110 primary neuroendocrine tumors (33 pancreatic, 31 pulmonary, 23 ileal, 14 rectal, and 9 gastric) and 73 metastatic neuroendocrine tumors (28 pancreatic, 5 pulmonary, 37 ileal, 1 rectal, 1 colonic, and 1 duodenal) were studied. Islet 1 and PAX8 were positive in 27/33 (82%) and 29/33 (88%), respectively, of primary pancreatic neuroendocrine tumors, and in 19/28 (68%) and 15/28 (54%), respectively, of metastatic pancreatic neuroendocrine tumors. No cases of primary (0/23) or metastatic (0/37) ileal neuroendocrine tumors were positive with either Islet 1 or PAX8. There was Islet 1 positivity in 2/31 (6%) primary pulmonary, 12/14 (86%) primary rectal, and 1/1 metastatic rectal neuroendocrine tumors, and PAX8 positivity in 7/31 (23%) primary pulmonary, 11/14 (79%) primary rectal, and 2/9 (22%) primary gastric neuroendocrine tumors. ROC curve analysis incorporating sensitivity and specificity data of immunohistochemical panels for metastatic pancreatic neuroendocrine tumors showed that a four-stain panel, including Islet 1, PAX8, TTF1, and CDX2 significantly outperformed a three-stain panel composed of PAX8, TTF1, and CDX2 (P=0.019), and also showed a trend for better performance compared with a three-stain panel composed of Islet 1, TTF1, and CDX2 (P=0.072). Both Islet 1 and PAX8 are reliable immunohistochemical markers for pancreatic neuroendocrine tumors and would be useful adjuncts to other markers (TTF1, CDX2) currently used to work up a metastatic neuroendocrine tumor of unknown primary.