Advanced Well-differentiated Neuroendocrine Tumors Research Articles

Phase II study of pembrolizumab and lenvatinib in advanced well-differentiated neuroendocrine tumors

Immune checkpoint inhibitors (CPIs) have not been shown to be active in well-differentiated neuroendocrine tumors (NETs), with response rates <5%. Lenvatinib is a multitargeted tyrosine kinase inhibitor which binds to vascular endothelial growth factor and fibroblast growth factor receptors and has demonstrated efficacy in pancreatic and gastrointestinal NETs [44% and 16% objective radiographic response rate (ORR), respectively]. The combination of antiangiogenic and CPI therapies can be synergistic. We therefore evaluated the combination of lenvatinib and pembrolizumab in well-differentiated gastrointestinal (GI) and thoracic NETs. A prospective, phase II trial evaluated patients with advanced GI/thoracic NETs (pancreatic NETs were excluded due to high response rate of lenvatinib monotherapy in this patient population), with evidence of progression within 8 months of study entry and at least two prior lines of systemic therapy. Patients received lenvatinib 20 mg daily and pembrolizumab 200 mg intravenously every 3 weeks until unacceptable toxicity or progression of disease. Primary endpoint was objective response rate, and an interim analysis was planned once 20 patients were enrolled. Four ORRs were required to continue enrollment. Twenty patients were enrolled on protocol from April 2021 to January 2022 (nine small intestine, five lung, two thymic, two unknown primary, one cecal, one presacral primaries). Two patients (10%) achieved a partial response (atypical lung and small intestinal primaries). Median progression-free survival (PFS) was 8 months (95% confidence interval 5.8-10.2 months). Twelve (60%) patients experienced probably or definitely associated grade 3 adverse events (10 hypertension). Fourteen patients (70%) required dose reductions or discontinued one of the medications. Two patients discontinued treatment before radiographic assessment. The combination of pembrolizumab and lenvatinib did not show sufficient response in patients with NETs to warrant continued enrollment on trial.

The Impact of Posttreatment Imaging in Peptide Receptor Radionuclide Therapy.

Posttreatment imaging of γ-emissions after peptide receptor radionuclide therapy (PRRT) can be used to perform quantitative dosimetry as well as assessment response using qualitative measures. We aimed to assess the impact of qualitative posttreatment imaging on the management of patients undergoing PRRT. Methods: In this retrospective study, we evaluated 100 patients with advanced well-differentiated neuroendocrine tumors undergoing PRRT, who had posttreatment SPECT/CT imaging at 24 h. First, we evaluated the qualitative assessment of response at each cycle. Then using a chart review, we determined the impact on management from the posttreatment imaging. The changes in management were categorized as major or minor, and the cycles at which these changes occurred were noted. Additionally, tumor grade was also evaluated. Results: Of the 100 sequential patients reviewed, most (80% after cycle 2, 79% after cycle 3, and 73% after cycle 4) showed qualitatively stable disease during PRRT. Management changes were observed in 27% (n = 27) of patients; 78% of those (n = 21) were major, and 30% (n = 9) were minor. Most treatment changes occurred after cycle 2 (33% major, 67% minor) and cycle 3 (62% major, 33% minor). Higher tumor grade correlated with increased rate of changes in management (P = 0.006). Conclusion: In this retrospective study, qualitative analysis of posttreatment SPECT/CT imaging informed changes in management in 27% of patients. Patients with higher-grade tumors had a higher rate of change in management, and most of the management changes occurred after cycles 2 and 3. Incorporating posttreatment imaging into standard PRRT workflows could potentially enhance patient management.

Oxaliplatin based chemotherapy for advanced well-differentiated neuroendocrine tumors: A systematic review and meta-analysis.

e16240 Background: Currently, chemotherapy is predominantly considered in advanced well-differentiated neuroendocrine tumors (NENs) with high ki67 proliferation index and tumor burden. So far, no standard regimen is available and alkylating agents alone, such as temozolomide or in combination with 5-fluorouracil or capecitabine are widely used. Besides, oxaliplatin based chemotherapy has shown promising antitumor activity without being influenced by the MGMT status. In the current SRMA, we aim to address the efficacy of oxaliplatin based chemotherapy in advanced well differentiated NENs. Methods: We conducted a systematic database search using PubMed/MEDLINE and EMBASE. Eligible studies included randomized and single-arm trials, prospective observational and retrospective studies documenting the clinical efficacy of oxaliplatin based chemotherapy for advanced well-differentiated NENs. The pooled overall response rate (ORR), median progression-free survival (PFS), and median overall survival (OS) were calculated and weighted using generic inverse variance in a random-effects model, as well as subgroup analysis for pts with pancreatic NETs (pNETs) and extra-pancreatic NETs (epNETs), G1-2 and G3 NETs. Results: 14 of 24 identified publications were included with a combined total of 865 patients in 3 phase II trial and 11 retrospective studies. 495 pts received FOLFOX, 155 pts XELOX, 130 pts GEMOX and 138 pts plus bevacizumab. 48.4% (419/865) patients were pNETs, and G3 NETs accounted for 21.7% (188/865). The pooled ORR was 27.9% (237/865, 95% CI: 23.2-32.5). pNETs showed much higher ORRs (37.7%,114/303, 95% CI: 31.1-44.3) than epNETs (14.9%, 40/251, 95% CI: 10.5-19.2), χ2 = 32.17, p &lt; 0.001. ORRs in G1-2 NETs was 23.1% (66/273, 95% CI: 18.2-28.1), while in G3 NETs was 45.7% (42/85, 95% CI: 29.7-61.6), χ2 = 19.60, p &lt; 0.001. FOLFOX plus bevacizumab showed a higher ORR (38.3%, 38/98, 95% CI: 28.8-47.9) than the oxaliplatin based regimens without bevacizumab (26.9%, 166/594, 95% CI: 23.4-30.4), χ2 = 4.745, p = 0.029. The median PFS in pNETs was 8.1 months (n = 247, 95% CI: 6.3-9.9), similar to 8.4 months in epNETs (n = 211, 95% CI 5.7-11.2). The median PFS in G1-G2 and G3 NET was 13.4 months (95% CI 9.1-17.6) and 7.1 months (95% CI 4.1-9.6) respectively. Besides, FOLFOX plus bevacizumab also showed a trend of a longer PFS (12.4months, 95% CI 9.5-15.2) than those without bevacizumab (7.6months, 95% CI 6.8-8.3). The pooled median overall survival was 28.8months (95% CI 26.7-30.9). Conclusions: Among the advanced well-differentiated neuroendocrine tumors, oxaliplatin based chemotherapy alone or plus bevacizumab could be a good alternative regimen, especially in pts with pNETs and G3 NETs.

Phase II Study of Pembrolizumab and Lenvatinib in Advanced Well-Differentiated Neuroendocrine Tumors

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Molecular factors, diagnosis and management of gastrointestinal tract neuroendocrine tumors: An update

The prevalence of gastrointestinal neuroendocrine tumors (GI-NETs) is increasing, and despite recent advances in their therapy, it remains inadequate in patients with advanced well-differentiated neuroendocrine tumors. These tumors present many challenges concerning the molecular basis and genomic profile, pathophysiology, clinicopathological features, histopathologic classification, diagnosis and treatment. There has been an ongoing debate on diagnostic criteria and clinical behavior, and various changes have been made over the last few years. Neuroendocrine carcinoma of the gastrointestinal system is a rare but highly malignant neoplasm that is genetically distinct from gastrointestinal system neuroendocrine tumors (NETs). The diagnosis and management have changed over the past decade. Emerging novel biomarkers and metabolic players in cancer cells are useful and promising new diagnostic tools. Progress in positron emission tomography-computerized tomography and scintigraphy with new radioactive agents (64Cu-DOTATATE or 68Ga-DOTATATE) replacing enough octreoscan, has improved further the current diagnostic imaging. Promising results provide targeted therapies with biological agents, new drugs, chemotherapy and immunotherapy. However, the role of surgery is important, since it is the cornerstone of management. Simultaneous resection of small bowel NETs with synchronous liver metastases is a surgical challenge. Endoscopy offers novel options not only for diagnosis but also for interventional management. The therapeutic option should be individualized based on current multidisciplinary information.

Molecular Profiling of Well-Differentiated Neuroendocrine Tumours: The Role of ctDNA in Real-World Practice.

Simple SummaryThe analysis of circulating tumour DNA (ctDNA) can help to identify genetic alterations present in cancer cells without the need to access tumour tissue, which can be an invasive approach. This study explored the feasibility of analysing ctDNA in patients with advanced well-differentiated neuroendocrine tumours (WdNETs). A total of 45 patients (15 with WdNETs) were included. Although feasible (with a non-evaluable sample rate of 27.8%), mutation-based ctDNA analysis was of limited clinical utility for patients with advanced WdNETs. While patients with WdNETs could still be offered genomic profiling (if available and reimbursed), it is important to manage patients’ expectations regarding the likelihood of the results impacting their treatment.Background: The role of tumour genomic profiling in the clinical management of well-differentiated neuroendocrine tumours (WdNETs) is unclear. Circulating tumour DNA (ctDNA) may be a useful surrogate for tumour tissue when the latter is insufficient for analysis. Methods: Patients diagnosed with WdNETs underwent ctDNA genomic profiling (FoundationLiquid®); non-WdNETs (paraganglioma, goblet cell or poorly-differentiated neuroendocrine carcinoma) were used for comparison. The aim was to determine the rate of: test failure (primary end-point), “pathological alterations” (PAs) (secondary end-point) and patients for whom ctDNA analysis impacted management (secondary end-point). Results: Forty-five patients were included. A total of 15 patients with WdNETs (18 ctDNA samples) were eligible: 8 females (53.3%), median age 63.2 years (range 23.5–86.8). Primary: small bowel (8; 53.3%), pancreas (5; 33.3%), gastric (1; 6.7%) and unknown primary (1; 6.7%); grade (G)1 (n = 5; 33.3%), G2 (9; 60.0%) and G3 (1; 6.7%); median Ki-67: 5% (range 1–30). A total of 30 patients with non-WdNETs (34 ctDNA samples) were included. Five WdNETs samples (27.78%) failed analysis (vs. 17.65% in non-WdNETs; p-value 0.395). Of the 13 WdNET samples with successful ctDNA analyses, PAs were detected in 6 (46.15%) (vs. 82.14% in non-WdNETs; p-value 0.018). In WdNETs, the PA rate was independent of concomitant administration anti-cancer systemic therapies (2/7; 28.57% vs. 4/6; 66.67%; p-value 0.286) at the time of the ctDNA analysis: four, one and one samples had one, two and three PAs, respectively. These were: CDKN2A mutation (mut) (one sample), CHEK2mut (one), TP53mut (one), FGFR2 amplification (one), IDH2mut (one), CTNNB1mut (one), NF1mut (one) and PALB2mut (one). None were targetable (0%) or impacted clinical management (0%). There was a lower maximum mutant allele frequency (mMAF) in WdNETs (mean 0.33) vs. non-WdNETs (mean 26.99), even though differences did not reach statistical significance (p-value 0.0584). Conclusions: Although feasible, mutation-based ctDNA analysis was of limited clinical utility for patients with advanced WdNETs. The rates of PAs and mMAFs were higher in non-WdNETs. While patients with WdNETs could still be offered genomic profiling (if available and reimbursed), it is important to manage patients’ expectations regarding the likelihood of the results impacting their treatment.

Advances in Targeted Therapy for Patients with Neuroendocrine Tumours

Neuroendocrine neoplasms are heterogenous tumours with diverse biological behaviour. Well-differentiated neuroendocrine tumours comprise the vast majority of these malignancies. Though a subset of patients may possess indolent disease, which can be observed, most patients require systemic therapy at some point. The treatment armamentarium for patients with metastatic or advanced well-differentiated neuroendocrine tumours has expanded significantly over recent years, with multiple regulatory approvals for systemic therapies. Though peptide receptor radionuclide therapy has been a major addition to this armamentarium, several targeted therapies have also been successfully developed. Herein, we discuss the approved targeted therapies sunitinib and everolimus and highlight the clinical experience with targeted therapies in development. We focus largely on novel receptor tyrosine kinases targeting vascular endothelial growth factor, inhibitors of cell-cycle drivers, metabolic-pathway inhibitors and chemotherapy, and immune-modulating agents targeting the somatostatin receptor.

Dual immune checkpoint blockade in advanced well-differentiated neuroendocrine tumors, a phase II clinical trial.

e16201 Background: Limited systemic treatment options are available for progressive well-differentiated neuroendocrine tumors (NET), also called carcinoid tumors. Given emerging evidence for immunotherapy response in high grade NET including small cell lung cancer, we sought to determine the efficacy of combination immunotherapy with ipilimumab and nivolumab in patients with advanced, progressive, well-differentiated NET in an open label phase II clinical trial. Methods: Eligible patients had well-differentiated, nonfunctional NET of lung, pancreas, or GI origin that had progressed within the past 12 months after at least one line of prior therapy. Patients received nivolumab 240 mg every 2 weeks and ipilimumab 1mg/kg every 6 weeks for up to 2 years. Primary endpoint was objective response rate (ORR) by RECIST v1.1. Using a Simon’s 2-stage design, the study planned to accrue up to 56 patients. Based on published response rates to everolimus of 5%, we hypothesized that this regimen would be considered promising if the true ORR is &gt; 15%. Results: Nine patients were enrolled prior to study closure due to funding, including 6 patients with NET of lung origin, 2 pancreatic, and 1 small bowel (Table). Median age was 71 years. All patients had distant metastatic disease at enrollment, with an average of 2 prior lines of therapy. Four of 9 patients achieved the primary endpoint of confirmed objective response, all of whom have ongoing response with a median duration of 15.4 months. Five of 9 patients, including all 4 responders, experienced immune-related toxicity requiring treatment modification or discontinuation. The trial did not accrue the target of 56 patients, however, objective response in 4 of 9 patients (ORR 44.4%, 90% CI: 16.9-74.9%) excluded the response rate target (15%). Conclusions: The impressive ORR of 44% with a median duration of response exceeding 15 months in this small clinical trial warrants further study of combination CTLA-4 and PD-1 inhibition in previously treated well-differentiated NET. Our ongoing immunologic and genomic correlative analysis in responders and non-responders will help inform future study of immunotherapy in this patient population in need of new systemic therapy approaches. Clinical trial information: NCT03420521. [Table: see text]

Efficacy of FOLFOX Chemotherapy in Metastatic Enteropancreatic Neuroendocrine Tumors.

FOLFOX (5-Fluorouracile and oxaliplatin) exhibits promising activity in advanced well-differentiated neuroendocrine tumors (NETs). This retrospective study aimed to analyze the outcome of metastatic enteropancreatic NETs patients treated with FOLFOX. We retrospectively identified patients treated with FOLFOX for NETs of enteropancreatic or unknown origin among those referred to our Regional Multidisciplinary Tumor Board. Among 48 patients, most often pancreatic NETs (n=33, 68.8%), the median Ki67 index was 10%. The median number cycle of FOLFOX was 6 and median follow-up was 34.8 months. Disease control rate (DCR) was 83.3%. Median PFS and OS were 12.6 and 29.4 months respectively. Median chemotherapy break was 14.1 months. No significant difference was observed between PFS and the following criteria: Ki67 index, primary tumor site, alkaline phosphatase levels, primary tumor surgery and 18F-FDG PET positivity. FOLFOX exhibits a high DCR and a short duration of treatment with a relative long chemotherapy break in patients with metastatic enteropancreatic NETs.

Prospective randomized phase II trial of pazopanib versus placebo in patients with progressive carcinoid tumors (CARC) (Alliance A021202).

4005 Background: Patients (pts) with progressive advanced well-differentiated neuroendocrine tumors arising outside of the pancreas have limited systemic treatment options. Pazopanib (PZ) is an oral multi-kinase inhibitor with activity against VEGFR-2,-3, PDGFR-α, and β, and c-KIT, with initial data suggesting efficacy in CARC. Methods: This was a multicenter, randomized, double-blind, phase II study of PZ (800 mg/day) versus placebo (PL) in progressive CARC. Key eligibility: low-intermediate grade CARC, radiologic progressive disease (PD) &lt; 12 months (mo), and adequate end-organ function. Prior somatostatin analog (SSA) mandated for midgut tumors. Concurrent SSA allowed if previous PD on SSA documented. Primary endpoint was progression-free survival (PFS), defined as time from randomization to PD by central review or death. Secondary endpoints included overall survival (OS), objective response rate (ORR) and safety. The trial had 85% power to detect a difference in median PFS of 14 v 9 mo (hazard ratio [HR] 0.64) at one-sided alpha = 0.1. A stratified log-rank test based on the intend-to-treat (ITT) principle was used. Unblinding and crossover were allowed if PD confirmed by central review. Results: 171 (97 PZ, 74 PL) pts were randomized between 6/2013-10/2015: median age 63; 56% female; 66% small bowel primary; 87% concurrent SSA. Median follow-up of 31 mo; 112 (56 PZ, 56 PL) PFS events observed. 6 pts (4 PZ, 2 PL) remain on initial treatment. Median PFS was 11.6 and 8.5 mo in PZ and PL, respectively (HR = 0.53, 1-sided 90% upper confidence limit [UCL] 0.69, p = 0.0005) which crossed the pre-specified protocol efficacy boundary. 49 PL pts received PZ after PD. Median OS was 41 and 42 mo in PZ and PL, respectively (HR = 1.13, 1-sided 90% UCL 1.51, p = 0.70). RR data will be presented. Notable grade 3+ adverse events were (PZ v. PL %) hypertension (35 v. 8), fatigue (11 v. 4), ALT (10 v. 0), AST (10 v. 0), and diarrhea (7 v. 4). Conclusions: PZ compared to PL was associated with significant improvement in PFS in patients with progressive CARC. The results confirm that VEGF signaling pathway is a valid target for therapy in CARC. Support: U10CA180821, U10CA180882 https://acknowledgments.alliancefound.org . Clinical trial information: NCT01841736.

Treatments for patients with advanced neuroendocrine tumors: a network meta-analysis.

Background:It remains unknown which is the most effective regimen among the available therapies for advanced well-differentiated neuroendocrine tumors (NETs). We performed a network meta-analysis to address this important issue.Methods:PubMed, Embase, Web of Science, Cochrane Library, and major international scientific meetings were searched for relevant randomized controlled trials (RCTs). Progression-free survival (PFS) data was the primary outcome of interest, and overall survival (OS) and serious adverse events (SAEs) were the secondary outcomes of interests, reported as hazard ratio (HR), or odds ratio (OR) and 95% confidence intervals (CIs).Results:Included in the meta-analysis were 21 eligible articles reporting 15 RCTs with a total of 2922 patients randomized to receive 11 treatments. Peptide receptor radionuclide therapy (PRRT) showed significant PFS advantage over somatostatin analogs (SSA) (HR = 0.21, 95% CI: 0.11–0.41), everolimus (HR = 0.25, 95% CI: 0.11–0.53), sunitinib (HR = 0.29, 95% CI: 0.10–0.82), everolimus+SSA (HR = 0.26, 95% CI: 0.12–0.54), and everolimus+bevacizumab (HR = 0.31, 95% CI: 0.11–0.82). OS findings were not significantly different between treatments. In terms of treatment rankings of PFS, PRRT had the highest probability (96%) of being the most effective treatment, followed by SSA+bevacizumab (86%) and SSA+interferon-α (IFN-α) (78%). As for toxicity, risk of SAEs was similar between the three treatments. Based on the benefit–risk ratio, PRRT, SSA+bevacizumab, and SSA+IFN-α seemed to be the best, second-, and third-best treatment, respectively.Conclusions:PRRT is likely to be the most preferable treatment for patients with advanced well-differentiated NETs. SSA+bevacizumab and SSA+IFN-α also seem to be more effective regimens with limited risk of SAEs.

My burning issues in neuroendocrine tumours (NET).

SummarySeveral compounds have recently been approved for the systemic treatment of advanced well-differentiated neuroendocrine tumours (NET) of gastroenteropancreatic (GEP) or lung origin. Based on the PROMID and CLARINET trials, somatostatin analogues (SSA) are the preferred first-line approach for all GEP-NET and offer—in addition to antiproliferative effects—durable symptomatic relief for hormonally active tumours. The mTOR inhibitor everolimus has been approved for progressive GEP- and lung-NET and is a widely used drug in this setting. Furthermore, recent results have underlined the high efficacy of somatostatin-receptor targeting radionuclide therapy (PRRT) in somatostatin-receptor positive midgut tumours and PRRT is now considered standard treatment for midgut-NET progressing on SSA. The optimal application of PRRT in somatostatin receptor positive NET with non-midgut site is currently an issue of discussion and should be decided on an individually basis in multidisciplinary boards. Following new insights in the genetic landscape of NET, “hot topics” in recent months include optimal treatment of the recently defined NET G3 and preliminary data on immunotherapy.

Somatostatin analogue-induced pancreatic exocrine insufficiency in patients with neuroendocrine tumors: results of a prospective observational study

ABSTRACTBackground: Patients with advanced well-differentiated neuroendocrine tumours (Wd-NETs) are commonly treated with somatostatin analogues (SSAs). Some patients may develop SSA-related side effects such as pancreatic exocrine insufficiency (PEI).Methods: In this prospective, observational study, the frequency of SSA-induced PEI in 50 sequential patients with advanced Wd-NETs treated with SSAs was investigated. Toxicity was assessed monthly and faecal elastase-1 (FE1) and quality of life (QoL) were assessed 3-monthly.Results: The median age was 65.8 years, 58% were male and the majority (92%) of patients had metastatic disease; patients received 4-weekly long acting octreotide (60%) or lanreotide (40%). Twelve patients (24%) developed SSA-related PEI after a median of 2.9 months from SSA initiation; FE1 was a reliable screening tool for PEI, especially in symptomatic (abdominal bloating, flatulence and/or diarrhea) patients (risk ratio 8.25 (95% confidence interval 1.15–59.01)). Most of these patients (11/12; 92%) required PERT. Other SSA-related adverse events (any grade) included flatulence (50%), abdominal pain (32%), diarrhoea (30%) and fatigue (20%). Development of PEI did not significantly worsen overall QoL, however gastrointestinal symptoms and diarrhoea were increased.Conclusion: This study demonstrated that PEI occurs at a higher rate than previously reported; clinicians need to diagnose and treat this SSA-related adverse-event which occurs in 1 in 4 patients with Wd-NETs treated with SSAs. Screening with FE1 in symtomatic patients is recommend.

Bevacizumab plus capecitabine in patients with progressive advanced well-differentiated neuroendocrine tumors of the gastro-intestinal (GI-NETs) tract (BETTER trial) – A phase II non-randomised trial

Aim of the studyGastro-intestinal neuroendocrine tumours (GI-NETs) are chemotherapy-resistant tumours. Bevacizumab, an inhibitor of vascular endothelial growth factor (VEGF), has shown promising results in several phase II trials of gastro-entero-pancreatic-NETs. We assessed bevacizumab combined with capecitabine, specifically in GI-NET patients. Patients and methodsBEvacizumab in The Treament of neuroEndocrine tumoRs (BETTER) was a multicentre, open-label, non-randomised, two-group phase II trial. Here we present the group of patients with progressive, metastatic, well-differentiated GI-NETs. Patients Eastern Cooperative Oncology Group-performance status (ECOG-PS)⩽2, Ki-67 proliferation rate <15% and no prior systemic chemotherapy were treated with bevacizumab (7.5mg/kg/q3w) and capecitabine (1000mg/m2 twice daily, orally d1–14, resumed on d22) for 6–24months. The primary end-point was progression-free survival (PFS); secondary end-points included overall survival (OS), response rate, safety and quality of life. ResultsOf the 49 patients included, 53% were men, median age was 60years (41–82), primary tumour site was ileal in 82% patients and Ki-67 was <15% in 48 patients and not available for one patient. After a maximum of 24month follow-up per patient, the median PFS by investigator assessment was 23.4months [95% confidence interval (CI): 13.2; not reached] and the overall disease control rate was 88% (18% partial response, 70% stable disease). The 2-year survival rate was 85%. Median OS was not reached. The most frequent grade 3–4 adverse events were hypertension (31%), diarrhoea (14%) and hand-foot syndrome (10%). ConclusionThe combination of bevacizumab and capecitabine showed clinical activity and a manageable safety profile in the treatment of GI-NETs that warrant confirmation in a randomised phase III trial.

75IN - Tools to Evaluate Tumour Response to Therapy: Imaging

ABSTRACT With neuroendocrine tumor, liver metastases are by far the most common site of recurrence of the disease. Liver mets pattern are now better known (hypervascular 60-83%, hypovascular 5%, and micronodular 22%). In the detection of liver metastases, MRI is more sensitive that CT scan, and adding diffuse weighted sequences to MRI can improve this sensitivity to 78–80%. Once detected, current ENETS guidelines recommend a staged approach to the management of liver metastases, depending on liver extend. If only one lobe is affected, surgery should be considered. If one lobe is predominantly affected, surgery and local ablative treatment are recommended. When a diffuse pattern is present, medical therapy, systemic chemotherapy and endovascular therapy are recommended, along with molecular targeted therapy. Then it is a challenge to evaluate tumour response due to these various therapies. Imaging can be effective in measuring reducing of tumour size, with RECIST. RECIST criteria, are accurate in assessing tumor progression but sometimes inaccurate in assessing tumor response after locoregional therapy or under molecular targeted therapy. There is poor correlation between tumor necrosis and conventional methods of response assessment, which poses questions of how best to quantify efficacy of targeted therapy. Choi criteria might also be considered as an alternative to RECIST to evaluate the effects of necrosis in patients with advanced well-differentiated neuroendocrine tumors because it takes in account necrosis. They are based on internal changes, tumor size (>10% decrease) OR tumor density (>15 HU decrease) Should we abandon RECIST? No, RECIST is still used in many clinical trials and is useful for assessing tumor progression. Then ENETS Modified Criteria are on study, associating RECIST and CHOI criteria. We probably should go back from RECIST 1.1 to RECIST, because RECIST 1.1 studies 2 targets per organ and Net liver mets have a large discrepancy of response. To choose 5 targets probably will lower discrepancy. Functional tools, mainly obtained with MR imaging, show interesting results but lack standardization. In the future, they will be combined to morphologic criteria Disclosure: All authors have declared no conflicts of interest.

The outcome of peptide receptor radionuclide therapy (PRRT) in North American patients with advanced well-differentiated neuroendocrine tumors (WD-NETs).

e14600 Background: PRRT is frequently used in Europe for patients with advanced WD-NETs, but it is not yet readily available in the USA. We analyzed data on 135 North American patients seen at our institution who underwent PRRT. Methods: Cases were identified by searching the University of Iowa Neuroendocrine Tumors Database. Groups were compared using a Wilcoxon rank-sum test, and survival was calculated with the Kaplan-Meier method. Results: Men were 64%, women 36%; median age at diagnosis was 51 years (18 – 78). The primary tumor originated in the small bowel (SBNET) in 37.8%, pancreas (PNET) 26.0%, lung 13.3%, unknown primary 9.6%, other sites 13.3%. PRRT was performed at the University of Basel, Switzerland in 68.8%, University of Iowa in 25.2%, and elsewhere in 6%. 90Y was used in 83.2% and 177Lu in 15.3% for the first PRRT. Median dose of radiation was 180 mCi (range 7.6 – 360). 116 patients received two treatments with median time between the treatments 2.1 months (range 0.4 – 110). Survival is shown in the table. Radiographic responses (any) at 1-6 months after PRRT were observed in 65.8%, 11.1% had a mixed response, and 15.4% progressed. A biochemical response (&gt;50% reduction in chromogranin A and pancreastatin levels) was seen in 18% and 17.3% respectively but data was frequently missing. Conclusions: North American patients with WD-NETs have a relatively long survival. The OS from 1st PRRT was much less than OS after diagnosis, suggesting that PRRT is used late in the disease course. PRRT appears to be a valuable treatment option for WD-NETs, especially SBNETS, and its role earlier in the disease course warrants investigation. [Table: see text]

Imaging response in neuroendocrine tumors treated with targeted therapies: the experience of sunitinib

Among neuroendocrine carcinomas of the gut, well-differentiated tumors are highly vascularized, featuring specific characteristics on contrast-enhanced imaging. Well-differentiated neuroendocrine tumors spontaneously harbor hypervascular enhancement, coexisting with areas of necrosis mainly located at the center of tumor lesions. When exposed to vascular endothelial growth factor (VEGFR) inhibitors such as sunitinib, target lesions display few if any variation in tumor size, but rather detectable modifications in tumor density. In several patients treated with targeted therapy, a significant decrease of tumor density at first tumor evaluation can be detected as compared to baseline. Consistently, the two randomized trials leading to approval of sunitinib and everolimus in pancreatic neuroendocrine tumors report objective response rate below 10%, emphasizing that Response Evaluation Criteria in Solid Tumors (RECIST), that focus only on the largest diameters of target lesions, may be insufficient to capture the full benefit of targeted therapies. Alternative criteria, such as those developed by Choi et al., consider both the size and the density of the tumor as parameters for response evaluation. Choi criteria have been recently proposed as a surrogate endpoint for efficacy and to identify patients that are good responders to VEGFR inhibitors such as sunitinib and sorafenib in advanced hepatocellular carcinoma, another disease highly addicted to angiogenesis. Preliminary data generated from patients included in the sunitinib phase III trial suggest that Choi criteria might also be considered as an alternative to RECIST to evaluate the effects of sunitinib in patients with advanced well-differentiated neuroendocrine tumors.

Potential Synergies for Combined Targeted Therapy in the Treatment of Neuroendocrine Cancer

Well differentiated neuroendocrine tumours (WDNET) are a diverse group of cancers that are often advanced at the time of diagnosis and generally do not respond significantly to traditional chemotherapy. A number of intriguing therapeutic targets have emerged, including somatostatin receptors, insulin-like growth factor-1 (IGF-1) and its receptor (IGF-1R), the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway, and vascular endothelial growth factor receptor. Functional somatostatin receptors and IGF-1R as well as dysregulated mTOR--a key pathway component for both growth factor signalling and protein synthesis--have been identified in human neuroendocrine tumour (NET) cell lines. Somatostatin analogues (SSA) and mTOR inhibitors have exhibited in vitro and in vivo antitumour activity against NET and have shown effects on the IGF-1 pathway in preclinical studies. SSA inhibit PI3K/Akt signalling upstream of mTOR, suggesting that the combination of an SSA and an mTOR inhibitor may have greater efficacy than either as single agents. Recent clinical trial experience has provided some encouraging findings and prompted the design of additional studies of this dual-targeted approach to treating advanced WDNET. Results of ongoing trials of dual-targeted therapy combinations will define future therapies for advanced WDNET.

Targeted Therapy in Advanced Well-Differentiated Neuroendocrine Tumors

Treatments for advanced neuroendocrine tumors were, until recently, rather limited. Salvage surgery and liver-directed therapy both have relatively limited impact, and systemic cytotoxic chemotherapy has minimal efficacy. In the absence of other effective treatments, somatostatin analogs have been used for years to control disease and neuroendocrine symptoms, without cytotoxic intent. Advances in targeted therapy for neuroendocrine tumors have opened several potentially new treatment paradigms in the management of these otherwise relatively drug-resistant neoplasms. Promising results have emerged from studies evaluating radiolabeled somatostatin analogs and inhibitors of the vascular endothelial growth factor and mammalian target of rapamycin pathways. This article reviews several of the more encouraging developments in this field.

Evaluation of the Combination 5-Fluorouracil, Dacarbazine, and Epirubicin in Patients With Advanced Well-Differentiated Neuroendocrine Tumors

The aim of this study was to retrospectively analyze the efficacy and safety of the combination of 5-fluorouracil (5-FU), dacarbazine, and epirubicin (FDE) in 39 patients with advanced, well-differentiated neuroendocrine tumors (NETs). The primary sites of the disease were the pancreas (16 cases), gastrointestinal tract (12 cases), and extradigestive sites (11 cases). Out of these, 54% of the patients were chemotherapy naive and 74% were progressive. The treatment was a combination of 5-FU 500 mg/m²/day, dacarbazine 250 mg/m²/day for 5 days, and epirubicin 50 mg/m² on day 1, administered every 21 days. Tumoral response was assessed with response evaluation criteria in solid tumors. Partial response was seen in 17 out of the 39 patients (44%) and the median response duration was 12 months. The median progression-free survival and overall survival were 11 and 21 months, respectively. Disease control was achieved in 83% of the 29 patients in progression at the beginning of the treatment. Objective responses were 58%, 25%, and 36%, for pancreatic, gastrointestinal, and extradigestive NETs, respectively. The sole grade 3/4 toxicity was hematologic. The FDE regimen is effective in advanced well-differentiated NETs and represents an interesting alternative to streptozocin-based regimens as first- or second-line therapy.