Consensus on biomarkers for neuroendocrine tumour disease

Orthopedia homeobox is preferentially expressed in typical carcinoids of the lung

BACKGROUND

Twenty-seven percent of neuroendocrine tumors (NETs) are associated with distant metastases, and in some patients, the primary site is unknown. Orthopedia homeobox protein (OTP) has been described as a useful marker for lung carcinoids (LCs) and for separating low-grade typical carcinoids (TCs) from intermediate-grade atypical carcinoids (ACs) in resection specimens. This study evaluated OTP, thyroid transcription factor 1 (TTF-1), and Ki-67 expression in fine-needle aspiration (FNA) samples of various NETs.

METHODS

A search for NETs diagnosed via FNA with subsequent resection was performed. Cell block sections were stained for OTP, TTF-1, and mindbomb E3 ubiquitin protein ligase 1 (Mib-1). Nuclear expression for OTP and TTF-1 was considered positive. Nuclear Ki-67 staining was reported as a percentage. Results were correlated with the grade and primary site for resection specimens.

RESULTS

Sixty-three FNA samples of NETs were identified: 14 liver samples, 14 pancreatic samples, 13 lymph node samples, 12 lung samples, 3 retroperitoneum samples, 2 small intestine samples, and 5 other samples. OTP was positive in 12 of 63 NETs (19%) from the following sites: lung (n = 8), liver (lung primary; n = 2), skin (n = 1), and lymph node (lung primary; n = 1). In well-differentiated NETs, only LCs were OTP-positive, whereas TTF-1 was positive in LCs and nonlung NETs (67% vs 7%). Within the LC category, OTP was positive in 100% of the TCs versus 17% of the ACs.

CONCLUSIONS

OTP is specific for LCs because well-differentiated nonlung NETs are negative for OTP. OTP preferentially stains TCs over ACs. In well-differentiated NETs, OTP staining is highly specific for LCs, and in combination with a low Ki-67 index, it suggests a pulmonary TC. Cancer Cytopathol 2018;126:236-42. © 2018 American Cancer Society.

MiR-20a-5p suppresses tumor proliferation by targeting autophagy-related gene 7 in neuroblastoma

Background

Neuroblastoma (NB) is the most common malignant tumor originating from the extracranial sympathetic nervous system in children. The molecular mechanisms underlying this disease are complex, and not completely understood.

Methods

Quantitative real-time PCR (qRT-PCR) was applied to quantify the expression of miR-20a-5p and its target gene ATG7 in clinical NB tissues. The biological function of miR-20a-5p and ATG7 in SH-SY5Y cells was investigated through in vitro studies (Real-Time cell kinetic analyzer, colony formation assay, caspase-Glo 3/7 assay and western blotting). The luciferase reporter assay was conducted to verify the biological relationship between miR-20a-5p and ATG7.

Results

Here we found that miR-20a-5p expression was significantly downregulated whereas its target autophagy-related gene 7 (ATG7) was increased along with clinical staging of NB progression. Correlation analysis showed that miR-20a-5p had a negative correlation trend with ATG7. In SH-SY5Y cells, forced expression of miR-20a-5p suppressed ATG7 expression, autophagy initiation and cellular proliferation while promoted apoptosis, suggesting a potential association between miR-20a-5p and ATG7. Further bioinformatic target prediction combined with protein expression and luciferase reporter assay verified that miR-20a-5p inhibited ATG7 by directly binding to its 3′-UTR, confirming the involvement of miR-20a-5p in the regulation of ATG7 in NB.

Conclusions

These results clarified that miR-20a-5p inhibited cell proliferation and promoted apoptosis through negative regulation of ATG7 and thus autophagy suppression in SH-SY5Y cells. Therefore, defining the context-specific roles of autophagy in NB and regulatory mechanisms involved will be critical for developing autophagy-targeted therapeutics against NB. Both miR-20a-5p and ATG7 would be potential therapeutic targets for future NB treatment.

Chromogranin A as circulating marker for diagnosis and management of neuroendocrine neoplasms: more flaws than fame

Owing to the heterogeneity of neuroendocrine neoplasms (NENs), the availability of reliable circulating markers is critical for improving diagnostics, prognostic stratification, follow-up and definition of treatment strategy. This review is focused on chromogranin A (CgA), a hydrophilic glycoprotein present in large dense core vesicles of neuroendocrine cells. Despite being long identified as the most useful NEN-related circulating marker, clinical application of CgA is controversial. CgA assays still lack standardization, thus hampering not only clinical management but also the comparison between different analyses. In the diagnostic setting, clinical utility of CgA is limited as hampered by (a) the variety of oncological and non-oncological conditions affecting marker levels, which impairs specificity; (b) the fact that 30-50% of NENs show normal CgA, which impairs sensitivity. Regarding the prognostic phase, there is prospective evidence which demonstrates that advanced NENs secreting CgA have poorer outcome, as compared with those showing non-elevated marker levels. Although the identification of cut-offs allowing a proper risk stratification of CgA-secreting patients has not been performed, this represents the most important clinical application of the marker. By contrast, based on prospective studies, the trend of elevated circulating CgA does not represent a valid indicator of morphological evolution and has therefore no utility for the follow-up phase. Ultimately, current knowledge about the role of the marker for the definition of treatment strategy is poor and is limited by the small number of available studies, their prevalent retrospective nature and the absence of control groups of untreated subjects.

Blood Transcript Profiling for the Detection of Neuroendocrine Tumors: Results of a Large Independent Validation Study

Background: Available neuroendocrine biomarkers are considered to have insufficient accuracy to discriminate patients with gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs) from healthy controls. Recent studies have demonstrated a potential role for circulating neuroendocrine specific transcripts analysis-the NETest-as a more accurate biomarker for NETs compared to available biomarkers. This study was initiated to independently validate the discriminative value of the NETest as well as the association between tumor characteristics and NETest score. Methods: Whole blood samples from 140 consecutive GEP-NET patients and 113 healthy volunteers were collected. Laboratory investigators were blinded to the origin of the samples. NETest results and chromogranin A (CgA) levels were compared with clinical information including radiological imaging to evaluate the association with tumor characteristics. Results: The median NETest score in NET patients was 33 vs. 13% in controls (p < 0.0001). The NETest did not correlate with age, gender, tumor location, grade, load, or stage. Using the cut-off of 14% NETest sensitivity and specificity were 93 and 56%, respectively, with an AUC of 0.87. The optimal cut-off for the NETest in our population was 20%, with sensitivity 89% and specificity 72%. The upper limit of normal for CgA was established as 100 μg/l. Sensitivity and specificity of CgA were 56 and 83% with an AUC of 0.76. CgA correlated with age (rs = 0.388, p < 0.001) and tumor load (rs = 0.458, p < 0.001). Conclusions: The low specificity of the NETest precludes its use as a screening test for GEP-NETs. The superior sensitivity of the NETest over CgA (93 vs. 56%; p < 0.001), irrespective of the stage of the disease, emphasize its potential as a marker of disease presence in follow up as well as an indicator for residual disease after surgery.

Pro (With Caution): Extended oncologic indications in liver transplantation

The success of liver transplantation (LT) in curing cancer (particularly hepatocellular carcinoma and hepatic metastases from neuroendocrine tumors) is based on the augmented oncologic potentials of the total hepatectomy and on restrictive criteria applied to patient selection. Consensus on the grade of expansion of conventional limits and implementation of alternative indications to LT (cholangiocarcinoma and metastases from colorectal cancer) has not been reached. On top of regional/local conditions for wait-list dynamics and organ availability, expanded cancer indications for LT should be explored with caution. Prospective investigations should rely on staging protocols predicting the exclusive hepatic location of cancer; restrictions on clinical conditions, tumor biology, and molecular profile, including the response to neoadjuvant therapies; confirmed tumor nonresectability with curative intent; sufficient life span of the transplant candidates to assess survival and transplant benefit; and use of marginal and extended criteria donors. In conclusion, the arguments supporting moderately loosened criteria for cancer seem more valid today than in the past. Transplant oncology is likely to represent a leading field in the near future, also because comorbidities and transplant-related causes of death are better managed and often eliminated. Liver Transplantation 24 98-103 2018 AASLD.

A liquid biopsy for bronchopulmonary/lung carcinoid diagnosis

No effective blood biomarker exists to detect and clinically manage bronchopulmonary (BP) neuroendocrine tumors (NET). We developed a blood-based 51 NET-specific transcript set for diagnosis and monitoring and evaluated clinical performance metrics. It accurately diagnosed the tumor and differentiated stable from progressive disease as determined by RECIST criteria. Gene expression was evaluated in: a) publicly available BPNET transcriptomes (GSE35679); b) two BPNET cell-lines; and c) BPNET tissue with paired blood (n = 7). Blood gene expression was assessed in 194 samples including controls, benign lung diseases, malignant lung diseases and small bowel NETs. A separate validation study in 25 age- and gender-matched BPNETs/controls was performed. Gene expression measured by real-time PCR was scored (0–100%; normal: < 14%). Regression analyses, Principal Component Analysis (PCA), hierarchical clustering, Fisher's and non-parametric evaluations were undertaken. All 51 genes were identified in BPNET transcriptomes, tumor samples and cell-lines. Significant correlations were evident between paired tumor and blood (R2:0.63–0.91, p < 0.001). PCA and hierarchical clustering identified blood gene expression was significantly different between lung cancers and benign diseases, including BPNETs. Gene expression was highly correlated (R²: 0.91, p = 1.7 × 10-¹⁵) between small bowel and BPNET. For validation, all 25 BPNETs were positive compared to 20% controls (p < 0.0001). Scores were significantly elevated (p < 0.0001) in BPNETs (57 ± 28%) compared to controls (4 ± 5%). BPNETs with progressive disease (85 ± 11%) exhibited higher scores than stable disease (32 ± 7%, p < 0.0001). Blood measurements accurately diagnosed bronchopulmonary carcinoids, distinguishing stable from progressive disease. This marker panel will have clinical utility as a diagnostic liquid biopsy able to define disease activity and progression in real-time.

Surgical Therapy of Sporadic Pancreatic Neuroendocrine Neoplasias G1/G2

Background

Pancreatic neuroendocrine neoplasias (pNENs) are uncommon but fascinating tumors with an annual incidence of 1 per 100,000 people. pNENs present either as functional tumors, causing specific hormonal syndromes like Zollinger-Ellison syndrome (ZES) or organic hyperinsulinism, or as non-functional pancreatic tumors (NF-pNENs). The natural history of pNENs is highly variable. 90% of all insulinomas or small NF- pNENs are readily curable by surgical resection. Most other functional and late detected NF-pNENs have a less favorable chance for cure.

Methods

A systematic review of the literature was performed to identify the current state of the art with regard to the key issues of surgery in pNEN G1/G2.

Results

This article provides a comprehensive review of the current literature addressing the current challenges in pNEN surgery.

Conclusion

Patients with completely resected tumors generally have a good prognosis, and an aggressive surgical approach combined with conservative treatment options in patients with advanced disease rarely provides cure but often results in long-term survival.

Long-Term Natural Course of Small Nonfunctional Pancreatic Neuroendocrine Tumors in MEN1-Results From the Dutch MEN1 Study Group

BACKGROUND

Pancreatic neuroendocrine tumors (pNETs) are highly prevalent in patients with multiple endocrine neoplasia type 1 (MEN1), and metastatic disease is an important cause of MEN1-related mortality. Especially small nonfunctional (NF) pNETs pose a challenge to the treating physician and more information is needed regarding their natural course. We assessed long-term natural history of small NF-pNETs and its modifiers in the Dutch MEN1 population.

PATIENTS AND METHODS

Retrospective longitudinal observational cohort study of patients with small (<2 cm) NF-pNETs from the Dutch national MEN1 database, which includes >90% of the Dutch MEN1 population. Modifiers of long-term natural course were analyzed using linear mixed-models analysis.

RESULTS

Growth rate of the 115 included small NF-pNETs from 99 patients was slow (0.4 mm/y; 95% confidence interval, 0.15 to 0.59). Seventy percent of the tumors was stable and a subgroup of 30% of the tumors was growing (1.6 mm/y; 95% confidence interval, 1.1 to 2.0). No differences in clinical characteristics were identified between growing and stable tumors. Within the subgroup of growing tumors, germline missense mutations were significantly associated with accelerated growth compared with nonsense and frameshift mutations.

CONCLUSION

The majority of small NF-pNETs are stable at long-term follow-up, irrespective of the underlying MEN1 genotype. A subgroup of tumors is slowly growing but cannot be identified on clinical grounds. In this subgroup, tumors with missense mutations exhibited faster growth. Additional events appear necessary for pNETs to progress. Future studies should be aimed at identifying these molecular driving events, which could be used as potential biomarkers.

The future: medical advances in MEN1 therapeutic approaches and management strategies

Multiple endocrine neoplasia type 1 is a rare autosomal inherited disorder associated with a high risk for patients to simultaneously develop tumors of the parathyroid glands, duodenopancreatic neuroendocrine tumors and tumors of the anterior pituitary gland. Early identification of MEN1 in patients enables presymptomatic screening of manifestations, which makes timely interventions possible with the intention to prevent morbidity and mortality. Causes of death nowadays have shifted toward local or metastatic progression of malignant neuroendocrine tumors. In early cohorts, complications like peptic ulcers in gastrinoma, renal failure in hyperparathyroidism, hypoglycemia and acute hypercalcemia were the primary causes of early mortality. Improved medical treatments of these complications led to a significantly improved life expectancy. The MEN1 landscape is still evolving, considering the finding of breast cancer as a new MEN1-related manifestation and ongoing publications on follow-up and medical care for patients with MEN1. This review aims at summarizing the most recent insights into the follow-up and medical care for patients with MEN1 and identifying the gaps for future research.

Immunohistochemical Characterization of the Origins of Metastatic Well-differentiated Neuroendocrine Tumors to the Liver

Metastatic neoplasms of unknown primary site pose a major challenge to patient management. As targeted therapies are now being tailored to neuroendocrine tumors (NETs) of different primary sites, identifying the origin of metastatic NETs has become increasingly important. Compared with more extensive efforts on metastatic adenocarcinomas of unknown primary, the literature on metastatic NETs (often to the liver) is relatively sparse and most studies are based on primary tumors. We sought to study metastatic well-differentiated NETs to the liver to identify markers that predict the site of origin. Eighty-five metastatic NETs to the liver were retrieved from the pathology archive. The primary sites were determined based on either pathologic review of the primary tumors (in most cases) or radiologic/clinical findings. Immunohistochemical labeling for TTF1, CDX2, ISL1, NKX2.2, and PDX1 was performed on either tissue microarrays or whole sections. The primary sites of the NETs in the study cohort included: pancreas (35%), small intestine (32%), rectum (8%), stomach (2%), bile duct (1%), lung (9%), and unknown primary (12%). We found predominant expression of TTF1 in lung carcinoid (63%), CDX2 in small intestinal (89%) and ISL1 in pancreatic NETs (77%), respectively. NKX2.2 was mainly expressed in NETs of the digestive organs. PDX1 was detected in a small percentage of pancreatic, small intestinal and the single bile duct NET. There was no statistically significant association between tumor grade (World Health Organization G1 vs. G2) and the expression of any of the above markers. The 3-marker panel (TTF1, CDX2, and ISL1) had sensitivities of 81%, 89%, and 63%, specificities of 100%, 94%, and 100%, positive predictive values of 100%, 89%, and 100%, and negative predictive values of 84%, 94%, and 96% in separating metastatic NETs into 3 major primary sites: pancreas/rectum, small intestine, and lung, respectively, with an overall accuracy of 82%. Furthermore, this panel predicted a primary site for 6 of the 10 NETs of unknown primary, which reduced the NETs of unknown primary from 12% to 5%. Thus, through immunohistochemical study of a large series of metastatic NETs to the liver, we have demonstrated the utility of a 3-marker panel for the identification of one or more potential primary sites of most metastatic NETs, which could provide practical guidance in patient management.

Histone deacetylase inhibitor thailandepsin-A activates Notch signaling and suppresses neuroendocrine cancer cell growth in vivo

Novel therapies for neuroendocrine (NE) cancers are desperately needed as they frequently present as metastatic disease and cause debilitating symptoms by secreting excessive hormones. Induction of Notch isoforms has a tumor suppressive effect in NE cancer cell lines, and we have observed that histone deacetylase inhibitors (HDACi) potently activate Notch. In this study, we describe the potential for Burkholderia thailandensis-derived class I HDACi thailandepsin A (TDP-A) as a Notch activator and therapeutic agent against NE cancer. IC₅₀ for TDP-A was determined to be 4-6 nM in NE cancer cell lines (BON, MZ-CRC-1, and TT) without cytotoxicity to lung fibroblasts. The binding characteristics of TDP-A to its target HDAC1 was examined using bioluminescence resonance energy transfer (BRET). Western blot and flow cytometry analysis showed that TDP-A induces cell cycle arrest and apoptosis in a dose-dependent manner. TDP-A dose-dependently activated the Notch pathway as measured by increasing functional CBF1-luciferase reporter signal and mRNA and protein expressions of Notch isoforms, which were attenuated by pretreatment with γ-secretase inhibitor DAPT. Furthermore, TDP-A lead to changes in expression level of downstream targets of Notch pathway and reduced expression of NE cancer markers. An in vivo study demonstrated that TDP-A suppressed NE cancer progression. These results show that TDP-A, as a Notch activator, is a promising agent against NE cancers.

Urinary sampling for 5HIAA and metanephrines determination: revisiting the recommendations

CONTEXT

Biogenic amines such as 5-hydroxy-indole acetic acid (5HIAA) the main metabolite of serotonin or metanephrines (catecholamines metabolites) are used as biomarkers of neuroendocrine tumours.

OBJECTIVE

To re-evaluate the recommendations for urinary sampling (preservatives, diet, drugs, etc.) as many of the reported analytical interferences supporting these recommendations are related to obsolete assays.

METHODS

Bibliographic analysis of old and modern assays concerning preservation, extraction, assay and interferences.

RESULTS

5HIAA may degrade as soon as urine is excreted. Thus, acids as preservatives (hydrochloric or acetic acid) have to be immediately added. Care should be taken not to decrease the pH under 2. Urine preservative for metanephrine assays is not mandatory. Diets including serotonin-, tryptophan- and dopamine-rich foods have to be avoided depending on the biomarkers investigated (bananas, plantain, nuts, etc.). Tryptophan-rich over-the-counter formulas have to be prohibited when 5HIAA has to be assayed. Acetaminophen may interfere with electrochemical detection depending on high-pressure liquid chromatography (HPLC) parameters. No interference is known with mass spectrometric assays but with the one described for metanephrines determination. Some drugs interfere however with serotonin and catecholamines secretion and/or metabolism (monoamine oxidase inhibitors, serotonin or dopamine recapture inhibitors, etc.).

CONCLUSION

Revisited recommendations are provided for the diet, the drugs and the preservatives before HPLC coupled with electrochemical and mass spectrometry assays.

The role of elevated serum procalcitonin in neuroendocrine neoplasms of digestive system

INTRODUCTION

Elevated serum procalcitonin (PCT) was reported in patients with certain type of neuroendocrine neoplasms (NENs).

OBJECTIVE

The aim of this study was to assess the role of elevated serum PCT in NENs from digestive system.

PATIENTS AND METHODS

Serum PCT and serum CgA level were measured in 155 patients with NENs from digestive system.

RESULTS

Elevated serum PCT was found in 63 patients (40.6%). Grade 3 disease was a significant factor associated with elevated serum PCT (OR, 9.24; 95%CI, 3.04-28.08; P<0.001). Serum PCT level was significantly decreased after treatment both in patients with stable disease (P=0.003) and patients with partial remission (P=0.001). In these patients, serum PCT level significantly increased again at the time of progression disease (P=0.001). Elevated serum PCT was a significant factor of worse survival (HR, 2.86; 95%CI, 1.36-6.03; P=0.006). Compared with patients with normal serum PCT and CgA level, patients with either PCT or CgA elevated and patients with both PCT and CgA elevated had progressively worse survival. Additionally, PCT expression in tumor cells was found in 24.0% of patients but did not correlate with other clinicopathological factors, including serum PCT.

CONCLUSIONS

Serum PCT is elevated in part of patients with NENs of digestive system, especially in patients with grade 3 disease. Serum PCT level can help evaluate treatment response and its elevation indicates poor prognosis. Combination of serum PCT and CgA can improve outcome prediction.

Circulating tumor cells and miRNAs as prognostic markers in neuroendocrine neoplasms

The prognosis of neuroendocrine neoplasms (NENs) is widely variable and has been shown to associate with several tissue- and blood-based biomarkers in different settings. The identification of prognostic factors predicting NEN outcome is of paramount importance to select the best clinical management for these patients. Prognostic markers have been intensively investigated, also taking advantage of the most modern techniques, in the perspective of personalized medicine and appropriate resource utilization. This review summarizes the available data on the possible role of circulating tumor cells and microRNAs as prognostic markers in NENs.

Multiparametric plasma EV profiling facilitates diagnosis of pancreatic malignancy

Pancreatic ductal adenocarcinoma (PDAC) is usually detected late in the disease process. Clinical workup through imaging and tissue biopsies is often complex and expensive due to a paucity of reliable biomarkers. We used an advanced multiplexed plasmonic assay to analyze circulating tumor-derived extracellular vesicles (tEVs) in more than 100 clinical populations. Using EV-based protein marker profiling, we identified a signature of five markers (PDACEV signature) for PDAC detection. In our prospective cohort, the accuracy for the PDACEV signature was 84% [95% confidence interval (CI), 69 to 93%] but only 63 to 72% for single-marker screening. One of the best markers, GPC1 alone, had a sensitivity of 82% (CI, 60 to 95%) and a specificity of 52% (CI, 30 to 74%), whereas the PDACEV signature showed a sensitivity of 86% (CI, 65 to 97%) and a specificity of 81% (CI, 58 to 95%). The PDACEV signature of tEVs offered higher sensitivity, specificity, and accuracy than the existing serum marker (CA 19-9) or single-tEV marker analyses. This approach should improve the diagnosis of pancreatic cancer.

Association between neuroendocrine tumors biomarkers and primary tumor site and disease type based on total 68Ga-DOTATATE-Avid tumor volume measurements

OBJECTIVE

To determine the association between neuroendocrine tumor (NET) biomarker levels and the extent of disease as assessed by ⁶⁸Ga DOTATATE PET/CT imaging.

DESIGN

A retrospective analysis of a prospective database of patients with NETs.

METHODS

Fasting plasma chromogranin A (CgA), neuron-specific enolase (NSE), gastrin, glucagon, vasoactive intestinal peptide (VIP) and pancreatic polypeptide (PP), and 24-h urinary 5-hydroxyindoleacetic acid (5-HIAA) levels were measured. Correlation between biomarkers and total ⁶⁸Ga-DOTATATE-avid tumor volume (TV) was analyzed.

RESULTS

The analysis included 232 patients. In patients with pancreatic NETs (n = 112), ⁶⁸Ga-DOTATATE TV correlated with CgA (r = 0.6, P = 0.001, Spearman). In patients with multiple endocrine neoplasia type 1 (n = 39), ⁶⁸Ga-DOTATATE TV correlated with glucagon (r = 0.5, P = 0.01) and PP levels (r = 0.5, P = 0.049). In patients with von Hippel-Lindau (n = 24), plasma VIP (r = 0.5, P = 0.02) and PP levels (r = 0.7, P < 0.001) correlated with ⁶⁸Ga-DOTATATE TV. In patients with small intestine NET (SINET, n = 74), ⁶⁸Ga-DOTATATE TV correlated with CgA (r = 0.5, P = 0.02) and 5-HIAA levels (r = 0.7, P < 0.001), with 5-HIAA ≥8.1 mg/24 h associated with metastatic disease with high positive (81.8%) and negative (85.7%) predictive values (P = 0.001). ⁶⁸Ga-DOTATATE TV in patients with NET of unknown primary (n = 16) and those with NET of other primary location (n = 30) correlated with 5-HIAA levels (r = 0.8, P = 0.002 and r = 0.7, P = 0.02 respectively).

CONCLUSIONS

Our data supports the use of specific NET biomarkers based on the site of the primary NET and the presence of hereditary syndrome-associated NET. High urinary 5-HIAA levels indicate the presence of metastatic disease in patients with SINET.

Non-functioning pancreatic neuroendocrine tumors: Surgery or observation?

Incidentally detected, sporadic, nonfunctional pancreatic neuroendocrine tumors are increasingly diagnosed on imaging studies performed for unrelated purposes. Although their resection is usually recommended, controversy still exists regarding their optimal management, due to their highly variable and difficult to predict biologic behavior. Recently, several studies and guidelines advocated an expectant management approach in small size, low grade, incidentally diagnosed nonfunctional pancreatic neuroendocrine tumors. The aim of this study is to review and summarize the available literature addressing nonfunctional pancreatic neuroendocrine tumors, with an emphasis on surgical management controversies.

Profiling of metastatic small intestine neuroendocrine tumors reveals characteristic miRNAs detectable in plasma

Background

Current diagnostic and prognostic blood-based biomarkers for neuroendocrine tumors are limited. MiRNAs have tumor-specific expression patterns, are relatively stable, and can be measured in patient blood specimens. We performed a multi-stage study to identify and validate characteristic circulating miRNAs in patients with metastatic small intestine neuroendocrine tumors, and to assess associations between miRNA levels and survival.

Methods

Using a 742-miRNA panel, we identified candidate miRNAs similarly expressed in 19 small intestine neuroendocrine tumors and matched plasma samples. We refined our panel in an independent cohort of plasma samples from 40 patients with metastatic small intestine NET and 40 controls, and then validated this panel in a second, large cohort of 120 patients with metastatic small intestine NET and 120 independent controls.

Results

miRNA profiling of 19 matched small intestine neuroendocrine tumors and matched plasma samples revealed 31 candidate miRNAs similarly expressed in both tissue and plasma. We evaluated expression of these 31 candidate miRNAs in 40 independent cases and 40 normal controls, and identified 4 miRNAs (miR-21-5p, miR-22-3p, miR-29b-3p, and miR-150-5p) that were differently expressed in cases and controls (p<0.05). We validated these 4 miRNAs in a separate, larger panel of 120 cases and 120 controls. We confirmed that high circulating levels of miR-22-3p (p<0.0001), high levels of miR 21-5p, and low levels of miR-150-5p (p=0.027) were associated with the presence of metastatic small intestine NET. While levels of 29b-3p were lower in cases than in controls in both the initial cohort and the validation cohort, the difference in the validation cohort did not reach statistical significance. We further found that high levels of circulating miR-21-5p, high levels of circulating miR-22-3p and low levels of circulating miR-150-5p were each independently associated with shorter overall survival. A combined analysis using all three markers was highly prognostic for survival (HR 0.47, 95% CI 0.27-0.82).

Conclusions

Our study suggests that elevated circulating levels of miR-21-5p and miR-22-3p and low levels of miR-150-5p are characteristic in patients with metastatic small intestine neuroendocrine tumors, and further suggests that levels of these miRNAs are associated with overall survival. These observations provide the basis for further validation studies, as well as studies to assess the biological function of these miRNAs in small intestine neuroendocrine tumors.

Neuroendocrine, goblet cell and mixed adeno-neuroendocrine tumours of the appendix: updates, clinical applications and the future

Appendiceal neuroendocrine neoplasms are rare, clinically challenging tumours that are typically incidentally diagnosed, have a poorly understood biology and have controversy surrounding their management. Most are adequately treated with appendectomy, and although distant metastases are rare, the threat of disease dissemination remains and current guidelines possess poor accuracy in terms of selecting patients requiring more extensive surgery, i.e. oncological right-hemicolectomy. Areas covered: In this article, we discuss the presentation and diagnostic work-up of patients with appendiceal neuroendocrine neoplasms, and also examine the evidence base for existing management strategies. We highlight controversies within the management of these tumours, and anticipate avenues for further progress. Although no longer classified as neuroendocrine neoplasms, we also discuss two related forms of tumours with neuroendocrine features - goblet cell cancers and mixed adeno-neuroendocrine carcinomas. Expert commentary: Existing guidelines for the treatment of appendiceal neuroendocrine neoplasms are derived from a limited evidence base and are unable to accurately predict which patients require extensive attempts at surgical disease control. Future advances in the field of improved patient selection for more extensive surgery may be possible with multi-factorial tumour assessment integrating morphological and molecular analyses.

Predicting the survival of patients with small bowel neuroendocrine tumours: comparison of 3 systems

Neuroendocrine tumours (NET) are clinically challenging due to their unpredictable behaviour. Nomograms, grading and staging systems are predictive tools with multiple roles in clinical practice, including patient prognostication. The NET nomogram allocates scores for various clinicopathological parameters, calculating percentage estimates for 5- and 10-year disease-specific survival of patients with small bowel (SB) NET. We evaluated the clinical utility of three prognostic systems in 70 SB NET patients: the NET nomogram, the World Health Organisation (WHO)/European Neuroendocrine Tumour Society (ENETS) grading system and the American Joint Commission on Cancer (AJCC)/Union Internationale Contre le Cancer (UICC) TNM staging method. Using Kaplan-Meier methodology, neither the WHO/ENETS grade (P = 0.6) nor the AJCC/UICC stage (P = 0.276) systems demonstrated significant differences in patient survival in the cohort. The NET nomogram was well calibrated to our data set, displaying favourable prediction accuracy. Harrel's C-index for the nomogram (a measure of predictive power) was 0.65, suggesting good prediction ability. On Kaplan-Meier analyses, there were significant differences in patient survival when stratified into nomogram score-based risk groups: low-, medium- and high-risk tumours were associated with median estimated survivals of 156, 129 and 112 months, respectively (P = 0.031). Our data suggest that a multivariable analysis-based NET nomogram may be clinically useful for patient survival prediction. This study identifies the limitations of the NET nomogram and the imperfections of other currently used single or binary parameter methodologies for assessing neuroendocrine disease prognosis. The future addition of other variables to the NET nomogram will likely amplify the accuracy of this personalised tool.

ENETS Consensus Guidelines for the Standards of Care in Neuroendocrine Neoplasia: Peptide Receptor Radionuclide Therapy with Radiolabeled Somatostatin Analogues

The purpose of these guidelines is to assist physicians caring for patients with neuroendocrine neoplasia in considering eligibility criteria for peptide receptor radionuclide therapy (PRRT) and in defining the minimum requirements for PRRT. It is not these guidelines' aim to give recommendations on the use of specific radiolabelled somatostatin analogues for PRRT as different analogues are being used, and their availability is governed by varying international regulations. However, a recent randomized controlled trial, NETTER-1, has provided evidence that may establish ¹⁷⁷Lu-DOTA-octreotate (LutaThera®) as the first widely approved agent. It also makes recommendations on what minimal patient, tumour, and treatment outcome characteristics should be reported for PRRT to facilitate robust comparisons between studies.

NET Blood Transcript Analysis Defines the Crossing of the Clinical Rubicon: When Stable Disease Becomes Progressive

BACKGROUND/AIMS

A key issue in gastroenteropancreatic neuroendocrine tumors (GEP-NETs) is early identification and prediction of disease progression. Clinical evaluation and imaging are limited due to the lack of sensitivity and disease indolence. We assessed the NETest as a predictive and prognostic marker of progression in a long-term follow-up study.

METHODS

GEP-NETs (n = 34) followed for a median 4 years (2.2-5.4) were evaluated. WHO tumor grade/stage grade 1: n = 17, grade 2: n = 14, grade 3: n = 1 (for 2, no grade was available); 31 (91%) were stage IV. Baseline and longitudinal imaging and blood biomarkers were available in all, and progression was defined per standard clinical protocols (RECIST 1.0). The NETest was measured by quantitative PCR of blood and multianalyte algorithmic analysis (disease activity scaled 0-100% with low <40% and high activity risk cutoffs >80%); chromogranin A (CgA) was measured by radioimmunoassay (normal <150 µg/l); progression-free survival (PFS) was analyzed by Cox proportional-hazard regression and Kaplan-Meier analysis.

RESULTS

At baseline, 100% were NETest positive, and CgA was elevated in 50%. The only baseline variable (Cox modeling) associated with PFS was NETest (hazard ratio = 1.022, 95% confidence interval = 1.005-1.04; p < 0.012). Using Kaplan-Meier analyses, the baseline NETest (>80%) was significantly associated (p = 0.01) with disease progression (median PFS 0.68 vs. 2.78 years with <40% levels). The NETest was more informative (96%) than CgA changes (<under>></under>25%) in consistently predicting disease alterations (40%, p < 2 × 10-5, χ2 = 18). The NETest had an earlier time point change than imaging (1.02 ± 0.15 years). Baseline NETest levels >40% in stable disease were 100% prognostic of disease progression versus CgA (χ2 = 5, p < 0.03). Baseline NETest values <40% accurately (100%) predicted stability over 5 years (p = 0.05, χ2 = 3.8 vs. CgA).

CONCLUSION

The NETest correlated with a well-differentiated GEP-NET clinical status. The NETest has predictive and prognostic utility for GEP-NETs identifying clinically actionable alterations ∼1 year before image-based evidence of progression.

Advance in microRNA as a potential biomarker for early detection of pancreatic cancer

Pancreatic cancer is characterized as a disease with low survival and high mortality because of no effective diagnostic and therapeutic strategies available in clinic. Conventional clinical diagnostic methods including serum markers and radiological imaging (CT, MRI, EUS, etc.) often fail to detect precancerous or early stage lesions. Development of effective biomarkers is unmet for reduction of mortality of pancreatic cancer. MicroRNAs (miRNAs) are a group of small non-protein-coding RNAs playing roles in regulation of cell physiology including tumorigenesis, apoptotic escape, proliferation, invasion, epithelial-mesenchymal transition (EMT), metastasis and chemoresistance. Various altered signaling pathways involving in molecular pathogenesis of pancreatic cancer are mediated by miRNAs as a role of either oncogenes or tumor suppressors. Among biomarkers developed including protein, metabolites, DNA, RNA, epigenetic mutation, miRNAs are superior because of its unique chemical property. Recent study suggests that miRNAs may be promising biomarkers used for early detection of pancreatic cancer. This review will update the progression made in early detection of pancreatic cancer.

Identifying and Prioritizing Gaps in Neuroendocrine Tumor Research: A Modified Delphi Process With Patients and Health Care Providers to Set the Research Action Plan for the Newly Formed Commonwealth Neuroendocrine Tumor Collaboration

Purpose

Neuroendocrine tumors (NETs) are a diverse group of malignancies that pose challenges common to all rare tumors. The Commonwealth Neuroendocrine Tumor Collaboration (CommNETS) was established in 2015 to enhance outcomes for patients with NETs in Canada, Australia, and New Zealand. A modified Delphi process was undertaken involving patients, clinicians, and researchers to identify gaps in NETs research to produce a comprehensive and defensible research action plan.

Methods

A three-round modified Delphi process was undertaken with larger representation than usual for medical consensus processes. Patient/advocate and health care provider/researcher expert panels undertook Round 1, which canvassed 17 research priorities and 42 potential topics; in Round 2, these priorities were ranked. Round 3 comprised a face-to-face meeting to generate final consensus rankings and formulate the research action plan.

Results

The Delphi groups consisted of 203 participants in Round 1 (64% health care providers/researchers, 36% patient/advocates; 52% Canadian, 32% Australian, and 17% New Zealander), of whom 132 participated in Round 2. The top eight priorities were biomarker development; peptide receptor radionuclide therapy optimization; trials of new agents in advanced NETs; functional imaging; sequencing therapies for metastatic NETs, including development of validated surrogate end points for studies; pathologic classification; early diagnosis; interventional therapeutics; and curative surgery. Two major areas were ranked significantly higher by patients/advocates: early diagnosis and curative surgery. Six CommNETS working parties were established.

Conclusion

This modified Delphi process resulted in a well-founded set of research priorities for the newly formed CommNETS collaboration by involving a large, diverse group of stakeholders. This approach to setting a research agenda for a new collaborative group should be adopted to ensure that research plans reflect unmet needs and priorities in the field.

Summary of emerging personalized medicine in neuroendocrine tumors: are we on track?

Neuroendocrine tumors (NETs) comprise a heterogeneous group of malignancies, with differences in prognosis and effective therapies. Traditionally, NETs have been characterized by tumor grade, site of primary tumor, functional status, and presence of underlying familial syndrome. However, increased feasibility and utilization of next-generation sequencing and other methodologies have revealed new genomic and epigenetic aberrations. In the last decade, treatment options available for metastatic well-differentiated gastroenteropancreatic (GEP) NETs have expanded, with approval of antiangiogenic and mTOR-directed targeted therapies, and our armamentarium of active therapies is likely to further increase. Cytotoxic therapies also are an important option for pancreatic NETs, and MGMT promoter methylation and protein expression may be an important biomarker for efficacy of alkylating agents. Peptide receptor radioligand therapy is an emerging treatment that uses functional imaging to personalize dosimetry to the tumor and avoid nephrotoxicity. Nevertheless, there is a critical need for further biomarkers, particularly multianalyte biomarkers, to aid in prognostication and predict efficacy of therapies.

miR-126 affects the invasion and migration of glioma cells through GATA4

We aimed to explore the relationship between miR-126 and glioma. miR-126 was highly expressed in low-grade clinical glioma tissue samples but lowly expressed in high-grade ones (P < .01). A human endogenous miR-126 expression vector was constructed. The migration capacity of cells transfected with the vector significantly decreased (P < .05). Up-regulation of miR-126 suppressed GATA4 protein expression. After transfection, they slightly contracted and became ovally or spherically shaped. F-actin significantly reduced, and microfilaments shortened or disappeared. The number of membrane-penetrating cells significantly decreased (P < .01). miR-126 inhibits the migration and invasion of glioma cells, which may be linked to GATA4 as a target gene.

Clinical Translation of a Click-Labeled 18F-Octreotate Radioligand for Imaging Neuroendocrine Tumors

We conducted the first-in-human study of (18)F-fluoroethyl triazole [Tyr(3)] octreotate ((18)F-FET-βAG-TOCA) in patients with neuroendocrine tumors (NETs) to evaluate biodistribution, dosimetry, and safety. Despite advances in clinical imaging, detection and quantification of NET activity remains a challenge, with no universally accepted imaging standard.

METHODS

Nine patients were enrolled. Eight patients had sporadic NETs, and 1 had multiple endocrine neoplasia type 1 syndrome. Patients received 137-163 MBq (mean ± SD, 155.7 ± 8 MBq) of (18)F-FET-βAG-TOCA. Safety data were obtained during and 24 h after radioligand administration. Patients underwent detailed whole-body PET/CT multibed scanning over 4 h with sampling of venous bloods for radioactivity and radioactive metabolite quantification. Regions of interest were defined to derive individual and mean organ residence times; effective dose was calculated with OLINDA 1.1.

RESULTS

All patients tolerated (18)F-FET-βAG-TOCA with no adverse events. Over 60% parent radioligand was present in plasma at 60 min. High tumor (primary and metastases)-to-background contrast images were observed. Physiologic distribution was seen in the pituitary, salivary glands, thyroid, and spleen, with low background distribution in the liver, an organ in which metastases commonly occur. The organs receiving highest absorbed dose were the gallbladder, spleen, stomach, liver, kidneys, and bladder. The calculated effective dose over all subjects (mean ± SD) was 0.029 ± 0.004 mSv/MBq.

CONCLUSION

The favorable safety, imaging, and dosimetric profile makes (18)F-FET-βAG-TOCA a promising candidate radioligand for staging and management of NETs. Clinical studies in an expanded cohort are ongoing to clinically qualify this agent.

Systemic therapies for advanced gastroenteropancreatic neuroendocrine tumors

Neuroendocrine tumors are a heterogeneous group of malignancies, characterised by production of hormones and vasoactive peptides. The incidence of gastroenteropancreatic neuroendocrine tumors (GEP-NET) is rising, and they have the highest prevalence amongst upper gastro-intestinal tumors. Diagnosis remains challenging due to wide variations in presentation and slow onset of symptoms. A multi-disciplinary approach is vital in appropriately managing the diverse spectrum of GEP-NET. Areas covered: Investigations in GEP-NET and biomarkers are described. Moreover, all available therapeutic options for GEP-NET including surgery, somatostatin analogues, targeted agents, Peptide Receptor Radionuclide Therapy and chemotherapy are also discussed. Expert commentary: The landscape of management has changed significantly in the last decade as a result of many practice-changing clinical trials. Long- acting somatostatin analogues are used not only for symptom control but also for their anti-proliferative effect. Targeted agents, such as everolimus and sunitinib, have improved PFS in GEP-NET. The recently presented NETTER-1 trial confirms the place of peptide receptor radionuclide treatment (PRRT) in treating NET. While chemotherapy remained an important option for high grade tumors. Despite promising results from recent trials, challenges include establishing the optimal sequencing of therapies to optimize outcome and preserve the quality of life.

Prognostic Value of the Pretreatment Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio for Patients with Neuroendocrine Tumors: An Izmir Oncology Group Study

BACKGROUND

Several studies evaluating the prognostic factors of gastrointestinal and pancreatic neuroendocrine tumors (GEP-NETs) have been published. The neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) have been accepted as prognostic factors for cancer patients.

MATERIALS AND METHODS

This study included 132 patients diagnosed with GEP-NETs. Peripheral blood samples were collected before the pretreatment period.

RESULTS

NLR and PLR were increased as the grade increased in NETs. The embryonic origin analysis revealed higher NLR and PLR rates in NETs of foregut origin. NLR and PLR were also higher in pancreatic NET patients compared to the gastroenteric NET patients. Analysis of NETs by TNM indicated that an advanced stage was accompanied by significantly higher NLR and PLR. We found a strong negative correlation between progression-free survival and NLR and PLR.

CONCLUSION

The study verified that NLR and PLR are simple laboratory findings that can be used to identify NETs with a worse outcome.

Predictive factors of response to mTOR inhibitors in neuroendocrine tumours

Medical treatment of neuroendocrine tumours (NETs) has drawn a lot of attention due to the recent demonstration of efficacy of several drugs on progression-free survival, including somatostatin analogs, small tyrosine kinase inhibitors and mTOR inhibitors (or rapalogs). The latter are approved as therapeutic agents in advanced pancreatic NETs and have been demonstrated to be effective in different types of NETs, with variable efficacy due to the development of resistance to treatment. Early detection of patients that may benefit from rapalogs treatment is of paramount importance in order to select the better treatment and avoid ineffective and expensive treatments. Predictive markers for therapeutic response are under intensive investigation, aiming at a tailored patient management and more appropriate resource utilization. This review summarizes the available data on the tissue, circulating and imaging markers that are potentially predictive of rapalog efficacy in NETs.

Chromogranin A: any relevance in neuroendocrine tumors?

PURPOSE OF REVIEW

The review summarizes the utility and limitations of chromogranin A (CgA) as a circulating biomarker for neuroendocrine tumors (NETs).

RECENT FINDINGS

Blood CgA measurement has numerous clinical limitations including poor assay reproducibility, low sensitivity (meta-analysis: 73%, 95% confidence interval: 0.71-0.76), and a paucity of prospective validation studies. A recent study noted elevation in 27% of NETs with a predictive value of 50% for metastases. These findings are consistent with its efficacy primarily as a monoanalyte secretory rather than multidimensional neoplastic marker. An automated CgA assay (KRYPTOR) exhibits similar metrics to the DAKO assay but is only useful in serum and routine storage diminishes its accuracy. Current studies indicate that CgA is more effective as a biomarker for cardiac disease. Given the diverse limitations of CgA, NET biomarker focus has evolved toward measurement of multiple analytes, for example, transcripts. Multianalyte algorithmic analyses perform significantly better as diagnostic (>95%) and prognostic markers (>90%) than CgA (30-74 and ∼50%, respectively) since they delineate different aspects of the biological behavior of NETs, (e.g., proliferome and metabolome).

SUMMARY

CgA is neither a reliable nor robust NET biomarker. As a monoanalyte, it is restricted by poor metrics and has limited predictive value. Its current clinical utility appears optimal in cardiovascular disease. The significance of CgA in NET disease is diminishing as other analytical approaches, particularly transcript multianalyte assays or other strategies, evolve to supersede it.

Multiple and Secondary Hormone Secretion in Patients With Metastatic Pancreatic Neuroendocrine Tumours

CONTEXT

As a group, neuroendocrine tumors (NETs) secrete many different peptide hormones, yet heretofore each NET patient is typically thought to produce at most one hormone that causes a distinct hormonal syndrome. A minority of patients have multiple hormones at diagnosis and may also develop secondary hormone secretion at a later stage.

OBJECTIVES

The objectives of the study were to determine the frequency and to describe the impact of multiple and secondary hormone secretion in sporadic gasteroenteropancreatic NET patients.

DESIGN, SETTING, AND PARTICIPANTS

This was a retrospective analysis of patients (n = 972) with gasteroenteropancreatic NET treated at Uppsala University Hospital, Uppsala, Sweden. Patients with the secretion of multiple hormones at diagnosis and/or those developing secondary hormone secretion during the disease course were identified and studied in further detail.

RESULTS

In pancreatic NETs (PNETs), a total of 19 of 323 patients (6%) had secretion of multiple hormones at diagnosis, and 14 of 323 (4%) had secondary changes during the disease course. These phenomena occurred exclusively in patients with an advanced disease stage, and secondary hormones were detected in a close time span with progressive disease. Patients with secondary insulin hypersecretion had increased morbidity as well as reduced survival (P < .002). In contrast, multiple and secondary hormone secretion was rarely seen in NETs of the small intestine with 0 and 1 of 603 cases, respectively.

CONCLUSION

Diversity of PNET hormone secretion either at diagnosis or during the disease course occurred in a minority of patients (9.3%). These phenomena had a major impact on patient outcome both through increased morbidity and mortality. Our results support that patients with metastatic PNETs should be monitored for clinical symptoms of secondary hormone secretion during the disease course.

Neuroendocrine tumor biomarkers: From monoanalytes to transcripts and algorithms

The management of neuroendocrine neoplasia remains a perplexing problem because of the lack of knowledge of the biology of the disease, its late presentation, the relative insensitivity of imaging modalities and a paucity of predictably effective treatment options. A critical limitation is posed by the lack of accurate biomarkers to guide management, monitor the efficacy of therapy and provide a prognostic assessment of disease progress. Currently utilized monoanalyte biomarkers (e.g. chromogranin, serotonin, pancreastatin etc.) exhibit variable metrics, poor sensitivity, specificity, and predictive ability and are rarely used to guide clinical decision making. A National Cancer Institute Neuroendocrine Tumor summit conference held in 2007 noted biomarker limitations to be a crucial unmet need in the management of neuroendocrine tumors. Nevertheless little progress has been made in this field until recently with the consideration of blood transcript analysis, circulating tumor cells and miRNA measurement. Given the complexity and multidimensionality of the neoplastic process itself, the heterogeneity of neuroendocrine tumors (NET) as well as the interaction of the tumor microenvironment, it is not unexpected that no single (monoanalyte) biomarker has proven to be effective. This deduction reflects the growing recognition that use of a monoanalyte to define a multidimensional disease process has inherent flaws. Logic dictates that no single measured parameter can capture the pathobiological diversity of neoplasia and monoanalytes cannot define the multiple variables (proliferation, metabolic activity, invasive potential and metastatic propensity) that constitute tumor growth. Thus far, most biomarkers whether in tissue or blood/urine have been single analytes with varying degrees of sensitivity and specificity and in general have failed to exhibit robust metrics or lacked methodological rigor. Neuroendocrine (NE) disease represents an area of biomarker paucity since the individual biomarkers (gastrin, insulin etc) are not widely applicable to the diverse types of NE neoplasia (NEN). Broad spectrum markers such as CgA have limitations in sensitivity, specificity and reproducibility. This review serves to provide a general background of the evolution of NET biomarkers. It provides an assessment of their current and past usage and limitations in assessing their diagnostic, pathologic and prognostic aspects in respect of NET. It provides a view of the changing methodology of biomarker development and the application of biomathematical analyses to redefining detection and treatment. Finally, it presents a description and consensus on current advances in transcript analysis, miRNA measurement and circulating tumor cell identification.