The IGF pathway is activated in insulinomas but downregulated in metastatic disease

Clinical and molecular studies have implicated epidermal growth factor receptor (EGFR), insulin-like growth factor (IGF) and target of rapamycin (mTOR) signaling pathways in the regulation of pancreatic neuroendocrine tumor (PanNET) growth. Interpretation and comparison of these studies is complex due to clinical and molecular tumor heterogeneity. We therefore focused in this study on insulinomas, which we examined for mRNA and protein expression of EGFR, IGF and mTOR signaling pathway components by quantitative real-time PCR (n=48) and immunohistochemistry (n=86). Findings were compared with normal pancreatic islets and correlated with histopathological data and clinical outcome. Insulinomas showed low EGFR and high IGF2 expression. IGFBP2, IGFBP3 and IGFBP6 mRNA levels were 2-4 folds higher than in islets. High protein expression of IGF2, IGF1R and INSR (in 51-92% of the tumors) and low to moderate expression of mTORC1 pathway proteins p-PS6k and p-4EBP1 (7-28% of the tumors) were observed. Correlations were found between 1) ERK1 mRNA expression and that of numerous IGF pathway genes, 2) p-ERK and IGF1R protein expression and 3) decrease of IGF pathway components and both metastatic disease and shorter 10 years disease free survival. In conclusion, our observations suggest that high expression of IGF signaling pathway components is a hallmark of insulinomas, but does not necessarily lead to increased mTOR signaling. Reduced expression of IGF pathway components may be an adverse prognostic factor in insulinomas.

Integrated Genomic and Immunophenotypic Classification of Pancreatic Cancer Reveals Three Distinct Subtypes with Prognostic/Predictive Significance

Purpose: Current clinical classification of pancreatic ductal adenocarcinoma (PDAC) is unable to predict prognosis or response to chemo- or immunotherapy and does not take into account the host reaction to PDAC cells. Our aim is to classify PDAC according to host- and tumor-related factors into clinically/biologically relevant subtypes by integrating molecular and microenvironmental findings.Experimental Design: A well-characterized PDAC cohort (n = 110) underwent next-generation sequencing with a hot spot cancer panel while next-generation tissue microarrays were immunostained for CD3, CD4, CD8, CD20, PD-L1, p63, hyaluronan-mediated motility receptor (RHAMM), and DNA mismatch repair proteins. Previous data on FOXP3 were integrated. Immune cell counts and protein expression were correlated with tumor-derived driver mutations, clinicopathologic features (TNM 8th edition, 2017), survival, and epithelial-mesenchymal transition (EMT)-like tumor budding.Results: Three PDAC subtypes were identified: the "immune escape" (54%), poor in T and B cells and enriched in FOXP3⁺ regulatory T cells (Treg), with high-grade budding, frequent CDKN2A, SMAD4, and PIK3CA mutations, and poor outcome; the "immune rich" (35%), rich in T and B cells and poorer in FOXP3⁺ Tregs, with infrequent budding, lower CDKN2A and PIK3CA mutation rate, and better outcome and a subpopulation with tertiary lymphoid tissue (TLT), mutations in DNA damage response genes (STK11 and ATM), and the best outcome; and the "immune exhausted" (11%), with immunogenic microenvironment and two subpopulations-one with PD-L1 expression and a high PIK3CA mutation rate and a microsatellite-unstable subpopulation with a high prevalence of JAK3 mutations. The combination of low budding, low stromal FOXP3 counts, presence of TLTs, and absence of CDKN2A mutations confers significant survival advantage in patients with PDAC.Conclusions: Immune host responses correlate with tumor characteristics, leading to morphologically recognizable PDAC subtypes with prognostic/predictive significance. Clin Cancer Res; 24(18); 4444-54. ©2018 AACRSee related commentary by Khalil and O'Reilly, p. 4355.

GKAP Acts as a Genetic Modulator of NMDAR Signaling to Govern Invasive Tumor Growth

Genetic linkage analysis previously suggested that GKAP, a scaffold protein of the N-methyl-D-aspartate receptor (NMDAR), was a potential modifier of invasion in a mouse model of pancreatic neuroendocrine tumor (PanNET). Here, we establish that GKAP governs invasive growth and treatment response to NMDAR inhibitors of PanNET via its pivotal role in regulating NMDAR pathway activity. Combining genetic knockdown of GKAP and pharmacological inhibition of NMDAR, we implicate as downstream effectors FMRP and HSF1, which along with GKAP demonstrably support invasiveness of PanNET and pancreatic ductal adenocarcinoma cancer cells. Furthermore, we distilled genome-wide expression profiles orchestrated by the NMDAR-GKAP signaling axis, identifying transcriptome signatures in tumors with low/inhibited NMDAR activity that significantly associate with favorable patient prognosis in several cancer types.

Competitive Testing of the WHO 2010 versus the WHO 2017 Grading of Pancreatic Neuroendocrine Neoplasms: Data from a Large International Cohort Study

BACKGROUND

The World Health Organization (WHO) and the American Joint Cancer Committee (AJCC) modified the grading of pancreatic neuroendocrine neoplasms from a three-tier (WHO-AJCC 2010) to a four-tier system by introducing the novel category of NET G3 (WHO-AJCC 2017).

OBJECTIVES

This study aims at validating the WHO-AJCC 2017 and identifying the most effective grading system.

METHOD

A total of 2,102 patients were enrolled; entry criteria were: (i) patient underwent surgery; (ii) at least 2 years of follow-up; (iii) observation time up to 2015. Data from 34 variables were collected; grading was assessed and compared for efficacy by statistical means including Kaplan-Meier method, Cox regression analysis, Harrell's C statistics, and Royston's explained variation in univariable and multivariable analyses.

RESULTS

In descriptive analysis, the two grading systems demonstrated statistically significant differences for the major category sex but not for age groups. In Cox regression analysis, both grading systems showed statistically significant differences between grades for OS and EFS; however, no statistically significant difference was observed between the two G3 classes of WHO-AJCC 2017. In multivariable analysis for the two models fitted to compare efficacy, the two grading systems performed equally well with substantially similar optimal discrimination and well-explained variation for both OS and EFS. The WHO-AJCC 2017 grading system retained statistically significant difference between the two G3 classes for OS but not for EFS.

CONCLUSIONS

The WHO-AJCC 2017 grading system is at least equally performing as the WHO-AJCC 2010 but allows the successful identification of the most aggressive PanNET subgroup. Grading is confirmed as probably the most powerful tool for predicting patient survival.

Expression of Contactin 4 Is Associated With Malignant Behavior in Pheochromocytomas and Paragangliomas

CONTEXT

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine, usually benign, tumors. Currently, the only reliable criterion of malignancy is the presence of metastases.

OBJECTIVE

The aim of this study was to identify genes associated with malignancy in PPGLs.

DESIGN

Transcriptomic profiling was performed on 40 benign and 11 malignant PPGLs. Genes showing a significantly different expression between benign and malignant PPGLs with a ratio ≥4 were confirmed and tested in an independent series by quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemistry was performed for the validated genes on 109 benign and 32 malignant PPGLs. Functional assays were performed with hPheo1 cells.

SETTING

This study was conducted at the Department of Pathology of the Erasmus MC University Medical Center Rotterdam Human Molecular Genetics laboratory of the de Duve Institute, University of Louvain.

PATIENTS

PPGL samples from 179 patients, diagnosed between 1972 and 2015, were included.

MAIN OUTCOME MEASURES

Associations between gene expression and malignancy were tested using supervised clustering approaches.

RESULTS

Ten differentially expressed genes were selected based on messenger RNA (mRNA) expression array data. Contactin 4 (CNTN4) was overexpressed in malignant vs benign tumors [4.62-fold; false discovery rate (FDR), 0.001]. Overexpression at the mRNA level was confirmed using qRT-PCR (2.90-fold, P = 0.02; validation set: 4.26-fold, P = 0.005). Consistent findings were obtained in The Cancer Genome Atlas cohort (2.7-fold; FDR, 0.02). CNTN4 protein was more frequently expressed in malignant than in benign PPGLs by immunohistochemistry (58% vs 17%; P = 0.002). Survival after 7 days of culture under starvation conditions was significantly enhanced in hPheo1 cells transfected with CNTN4 complementary DNA.

CONCLUSION

CNTN4 expression is consistently associated with malignant behavior in PPGLs.

Nationwide multicenter study on the management of pulmonary neuroendocrine (carcinoid) tumors

BACKGROUND AND AIM

To analyze the management and outcome of patients with primary typical (TC) and atypical lung carcinoids (AC) in Switzerland.

METHODS

Retrospective analysis of patients selected from a neuroendocrine tumor (NET) registry. Patients were divided into TC and AC according to pathology reports, and surgical procedures were grouped as wedge/segmentectomy, lobectomy/bilobectomy and pneumectomy. Survival analysis was performed using the Kaplan-Meier method and log-rank test.

RESULTS

Over 7 years, 113 pulmonary carcinoids (61.9% females, mean age 59.4 years) were included from 19 hospitals, with pathology data on Ki67 and necrosis incomplete in 16 cases. Eighty-three TC and 14 AC underwent surgical resection with a primary tumor size of median 14.5 (range 1-80) mm and diagnosis was established in 55.8% at surgery. Mean follow-up was 30.2 ± 23.1 months. Lobectomy was performed in 54.2% and wedge resection in 17.7% of cases. Six patients received additional systemic therapy. There was a trend for larger primary lesion size and a significantly higher rate of N2-N3 status in AC. Mean survival tended to be increased in patients with TC compared to AC (86.1 vs 48.4 months, P = 0.06) and mean disease-free interval after surgical resection was 74.1 and 48.3 months for TC and AC, respectively (P = 0.74).

CONCLUSION

AC of the lung has a more malignant behavior and a trend to a worse outcome. The results of this registry reinforce the need for standardized histological diagnosis and inter-disciplinary therapeutic decision making to improve the quality of care of patients with TC and AC.

Calcitonin-Producing Neuroendocrine Neoplasms of the Pancreas: Clinicopathological Study of 25 Cases and Review of the Literature

Increased levels of circulating calcitonin are a clue in the diagnosis of medullary thyroid carcinoma. However, hypercalcitoninemia can also be related to other pathological conditions, including pancreatic neuroendocrine neoplasms (PanNENs). Ectopic hormonal production is not unusual in both functioning and non-functioning PanNENs; however, little is known about the frequency of calcitonin expression in these neoplasms. The aims of this study were to assess the frequency of calcitonin immunoreactivity in PanNENs, independently from serum calcitonin levels, and to evaluate the clinicopathological and prognostic features of calcitonin-immunoreactive (Cal-IR) PanNENs, including a comparison with cases already reported in the literature. We screened 229 PanNENs for the immunohistochemical expression of calcitonin, including both functioning and non-functioning neoplasms, as well as both well-differentiated and poorly differentiated PanNENs. Both the clinicopathological data and the follow-up information were available and were compared with the immunohistochemical results. In addition, we reviewed the features of the calcitonin-producing PanNENs previously reported in the literature. Calcitonin was expressed in 25 of our 229 PanNENs (10.9%). Examples of well- and poorly differentiated, as well as both functioning and non-functioning PanNENs, were found to be calcitonin immunoreactive. Cal-IR PanNENs did not show any significant difference with the whole series of neoplasms included in the study, when the clinicopathological parameters were considered, except for a younger age at diagnosis and for a larger size of the tumor in non-functioning Cal-IR PanNENs. Taken together, our results show that calcitonin immunoreactivity is not an exceptional event in PanNENs. Furthermore, calcitonin expression does not identify a separate clinical entity, in contrast to other PanNENs with ectopic hormone production, such as adrenocorticotropic hormone (ACTH)-producing PanNENs, which show a distinctively more aggressive behavior.

Autophagy Inhibition Improves Sunitinib Efficacy in Pancreatic Neuroendocrine Tumors via a Lysosome-dependent Mechanism

Increasing the efficacy of approved systemic treatments in metastasized pancreatic neuroendocrine tumors (PanNET) is an unmet medical need. The antiangiogenic tyrosine kinase inhibitor sunitinib is approved for PanNET treatment. In addition, sunitinib is a lysosomotropic drug and such drugs can induce lysosomal membrane permeabilization as well as autophagy. We investigated sunitinib-induced autophagy as a possible mechanism of PanNET therapy resistance. Sunitinib accumulated in lysosomes and induced autophagy in PanNET cell lines. Adding the autophagy inhibitor chloroquine reduced cell viability in cell lines and in primary cells isolated from PanNET patients. The same treatment combination reduced tumor burden in the Rip1Tag2 transgenic PanNET mouse model. The combination of sunitinib and chloroquine reduced recovery and induced apoptosis in vitro, whereas single treatments did not. Knockdown of key autophagy proteins in combination with sunitinib showed similar effect as chloroquine. Sunitinib also induced lysosomal membrane permeabilization, which further increased in the presence of chloroquine or knockdown of lysosome-associated membrane protein (LAMP2). Both combinations led to cell death. Our data indicate that chloroquine increases sunitinib efficacy in PanNET treatment via autophagy inhibition and lysosomal membrane permeabilization. We suggest that adding chloroquine to sunitinib treatment will increase efficacy of PanNET treatment and that such patients should be included in respective ongoing clinical trials. Mol Cancer Ther; 16(11); 2502-15. ©2017 AACR.

Implementation of a 'lean' cytopathology service: towards routine same-day reporting

OBJECTIVES

To systematically assess the effects of a Lean management intervention in an academic cytopathology service.

METHODS

We monitored outcomes including specimen turnaround times during stepwise implementation of a lean cytopathology workflow for gynaecological and non-gynaecological cytology.

RESULTS

The intervention resulted in a major reduction of turnaround times for both gynaecological (3rd quartile 4.1 vs 2.3 working days) and non-gynaecological cytology (3rd quartile 1.9 vs. 1.2 working days). Introduction of fully electronic reporting had additional effect over continuous staining of slides alone. The rate of non-gynaecological specimens reported the same day increased from 4.5% to 56.5% of specimens received before noon.

CONCLUSIONS

Lean management principles provide a useful framework for organization of a cytopathology workflow. Stepwise implementation beginning with a simplified gynaecological cytology workflow allowed involved staff to monitor the effects of individual changes and allowed for a smooth transition.

Pathologie neuroendokriner Neoplasien: Angepasste Klassifikation, Gradierung und TNM Einteilung 2017: “Nomen est omen?”

Zusammenfassung. Neuroendokrine Neoplasien (NEN) haben seit der Erstbeschreibung vor etwas mehr als 100 Jahren als „Karzinoid“ mehrfach eine Namensänderung durchlaufen und erst seit einigen Jahren besteht ein international anerkanntes Gradierungs-System sowie eine TNM-Einteilung. Obwohl sich diese in der Praxis bewährt haben, waren einzelne Feinanpassungen nötig, welche in der neuen 4. WHO-Ausgabe über endokrine Tumoren sowie der 8. TNM-Ausgabe verankert sind. In dieser Übersichtsarbeit werden die wichtigsten Änderungen zusammengefasst. Sie beinhalten unter anderem: 1. Schaffung einer neuen Kategorie von hochproliferativen NEN mit gut differenzierter Morphologie (sog. NET G3), 2. Ersatz der Bezeichnung MANEC durch MiNEN für gemischte Tumoren, und 3. die Vereinheitlichung der ENETS, UICC sowie AJCC TNM-Einteilungen.

Androgen production in pediatric adrenocortical tumors may occur via both the classic and/or the alternative backdoor pathway

Children with adrenocortical tumors (ACTs) often present with virilization due to high tumoral androgen production, with dihydrotestosterone (DHT) as most potent androgen. Recent work revealed two pathways for DHT biosynthesis, the classic and the backdoor pathway. Usage of alternate routes for DHT production has been reported in castration-resistant prostate cancer, CAH and PCOS. To assess whether the backdoor pathway may contribute to the virilization of pediatric ACTs, we investigated seven children suffering from androgen producing tumors using steroid profiling and immunohistochemical expression studies. All cases produced large amounts of androgens of the classic and/or backdoor pathway. Variable expression of steroid enzymes was observed in carcinomas and adenomas. We found no discriminative pattern. This suggests that enhanced androgen production in pediatric ACTs is the result of deregulated steroidogenesis through multiple steroid pathways. Thus future treatments of ACTs targeting androgen overproduction should consider these novel steroid production pathways.

Genetic and epigenetic drivers of neuroendocrine tumours (NET)

Neuroendocrine tumours (NET) of the gastrointestinal tract and the lung are a rare and heterogeneous group of tumours. The molecular characterization and the clinical classification of these tumours have been evolving slowly and show differences according to organs of origin. Novel technologies such as next-generation sequencing revealed new molecular aspects of NET over the last years. Notably, whole-exome/genome sequencing (WES/WGS) approaches underlined the very low mutation rate of well-differentiated NET of all organs compared to other malignancies, while the engagement of epigenetic changes in driving NET evolution is emerging. Indeed, mutations in genes encoding for proteins directly involved in chromatin remodelling, such as DAXX and ATRX are a frequent event in NET. Epigenetic changes are reversible and targetable; therefore, an attractive target for treatment. The discovery of the mechanisms underlying the epigenetic changes and the implication on gene and miRNA expression in the different subgroups of NET may represent a crucial change in the diagnosis of this disease, reveal new therapy targets and identify predictive markers. Molecular profiles derived from omics data including DNA mutation, methylation, gene and miRNA expression have already shown promising results in distinguishing clinically and molecularly different subtypes of NET. In this review, we recapitulate the major genetic and epigenetic characteristics of pancreatic, lung and small intestinal NET and the affected pathways. We also discuss potential epigenetic mechanisms leading to NET development.

Abstract 3159: Lysosomal membrane permeabilization as potential mediator of resistance in pancreatic neuroendocrine tumors

Sunitinib, an anti-angiogenic tyrosine kinase inhibitor, is approved for treatment of pancreatic neuroendocrine tumors (pNETs). However, its efficacy is greatly limited due to resistance. Sunitinib is a lysosomotropic drug, thus accumulates in lysosomes, leading to their destabilization and to lysosomal membrane permeabilization (LMP), which in turn can lead to cell death. Autophagy might be activated for clearance of damaged lysosomes, thus promote survival and act as a mechanism of resistance. We found that the autophagy inhibitor chloroquine increases sunitinib efficacy in pNET cell lines and in a transgenic mouse model of pNETs. Interestingly, chloroquine is a lysosomotropic drug as well and the response towards sunitinib and chloroquine in pNET cell lines correlated with lysosome-associated membrane protein 2 (LAMP2) levels, which influence lysosome stability. We hypothesized that sunitinib and the combination with chloroquine induce LMP in pNETs and that LMP leads to activation of the transcription factor EB (TFEB), master regulator of genes involved in lysosomal biogenesis and autophagy, leading to therapy resistance. We found that LMP increased upon combined treatment of sunitinib and chloroquine compared to single treatment in pNET cell lines. Treatment of pNET cell lines with sunitinib or chloroquine led to activation of TFEB as assessed by nuclear/cytoplasmic fractionation and western blotting. Additionally, sunitinib significantly increased the expression of TFEB target genes, which were further upregulated upon combination with chloroquine. Interestingly, activation of TFEB and upregulation of TFEB target genes was more pronounced in the more resistant pNET cell line with respect to reduced viability and increased apoptosis. Our data indicate that sunitinib and chloroquine activate TFEB in pNET cell lines, leading to autophagy as a survival mechanism. Upon massive LMP or if autophagy is dysfunctional, cell death is induced. Based on our data, we suggest the combination of sunitinib and chloroquine as a treatment option for pNET patients and that TFEB could be an interesting therapeutic target in combination with lysosomotropic drugs.

Citation Format: Tabea Wiedmer, Rasmus M. Frank, Mario P. Tschan, Aurel Perren, Ilaria Marinoni. Lysosomal membrane permeabilization as potential mediator of resistance in pancreatic neuroendocrine tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3159. doi:10.1158/1538-7445.AM2017-3159

TERT Promoter Mutations but not the Alternative Lengthening of Telomeres Phenotype Are Present in a Subset of Ependymomas and Are Associated With Adult Onset and Progression to Ependymosarcoma

Genetic signatures related to telomere maintenance have emerged as powerful classifiers among CNS tumors. These include the alternative lengthening of telomeres (ALT) phenotype associated with mutations in the ATRX and DAXX genes and recurrent point mutations in the TERT gene promoter. We investigated a patient cohort covering the entire spectrum of childhood and adult ependymomas (n = 128), including subependymomas and myxopapillary ependymomas, for the presence of TERT promoter mutations, for loss of ATRX or DAXX expression by immunohistochemistry (as surrogates as underlying gene mutations), and for the ALT phenotype by fluorescence in situ hybridization (FISH). TERT promoter mutations were identified in 9/120 (7%) of tumors, all of which were conventional ependymomas occurring in adults. TERT promoter mutations were associated with older age and intracranial localization. Remarkably, 2 of these tumors progressed to ependymosarcoma upon recurrence. No tumors displayed an ALT phenotype by FISH or were ATRX or DAXX deficient by immunohistochemistry. In sum, TERT promoter mutations are present in a subset of mostly intracranial conventional ependymomas in adults and may be relevant for the uncommon progression to ependymosarcoma. Loss of ATRX immunoreactivity is a useful marker to rule out ependymoma in specific diagnostic settings.

Hypo-methylation mediates chromosomal instability in pancreatic NET

DAXX and or ATRX loss occur in 40% of pancreatic neuroendocrine tumors (PanNETs). PanNETs negative for DAXX or ATRX show an increased risk of relapse. The tumor-associated pathways activated upon DAXX or ATRX loss and how this event may induce chromosomal instability (CIN) and alternative lengthening telomeres (ALT) are still unknown. Both DAXX and ATRX are involved in DNA methylation regulation. DNA methylation of heterochromatin and of non-coding sequences is extremely important for the maintenance of genomic stability. We analyzed the association of DAXX and/or ATRX loss and CIN with global DNA methylation in human PanNET samples and the effect of DAXX knock-down on methylation and cell proliferation. We assessed LINE1 as well as global DNA methylation in 167 PanNETs, and we found that DAXX and or ATRX-negative tumors and tumors with CIN were hypomethylated. DAXX knock-down in PanNET cell lines blocked cells in G1/G0 phase and seemed to increase CIN in QGP-1 cells. However, no direct changes in DNA methylation were observed after DAXX knock-down in vitro In conclusion, our data indicate that epigenetic changes are crucial steps in the progression of PanNETs loss and suggest that DNA methylation is the mechanism via which CIN is induced, allowing clonal expansion and selection.

Genes and proteins of the alternative steroid backdoor pathway for dihydrotestosterone synthesis are expressed in the human ovary and seem enhanced in the polycystic ovary syndrome

Recently, dihydrotestosterone biosynthesis through the backdoor pathway has been implicated for the human testis in addition to the classic pathway for testosterone (T) synthesis. In the human ovary, androgen precursors are crucial for estrogen synthesis and hyperandrogenism in pathologies such as the polycystic ovary syndrome is partially due to ovarian overproduction. However, a role for the backdoor pathway is only established for the testis and the adrenal, but not for the human ovary. To investigate whether the backdoor pathway exists in normal and PCOS ovaries, we performed specific gene and protein expression studies on ovarian tissues. We found aldo-keto reductases (AKR1C1-1C4), 5α-reductases (SRD5A1/2) and retinol dehydrogenase (RoDH) expressed in the human ovary, indicating that the ovary might produce dihydrotestosterone via the backdoor pathway. Immunohistochemical studies showed specific localization of these proteins to the theca cells. PCOS ovaries show enhanced expression, what may account for the hyperandrogenism.

ENETS Consensus Guidelines for the Standards of Care in Neuroendocrine Tumors: Pathology: Diagnosis and Prognostic Stratification

The European Neuroendocrine Tumor Society (ENETS) proposed standard of care guidelines for pathology in 2009. Since then, profound changes in the classification have been made, dividing neuroendocrine neoplasia (NEN) into well-differentiated neuroendocrine tumors (NET) and poorly differentiated neuroendocrine carcinomas (NEC) in the 2010 WHO classification. The 7th edition of the TNM classification (2009) included NEN for the first time, widely adapting ENETS proposals but with some differences for NEC and for NET of the pancreas and the appendix. Therapy guidelines for gastroenteropancreatic NET were updated in 2016. The need for an update of the standards of care prompted the ENETS to organize a consensus conference which was held in Antibes in 2015; a working group was designated to propose pathological standards of care.

ENETS Consensus Guidelines for Standard of Care in Neuroendocrine Tumours: Biochemical Markers

Biomarkers have been the mainstay in the diagnosis and follow-up of patients with neuroendocrine tumors (NETs) over the last few decades. In the beginning, secretory products from a variety of subtypes of NETs were regarded as biomarkers to follow during diagnosis and treatment: serotonin for small intestinal (SI) NETs, and gastrin and insulin for pancreatic NETs. However, it became evident that a large number of NETs were so-called nonfunctioning tumors without secreting substances that caused hormone-related symptoms. Therefore, it was necessary to develop so-called “general tumor markers.” The most important ones so far have been chromogranin A and neuron-specific enolase (NSE). Chromogranin A is the most important general biomarker for most NETs with a sensitivity and specificity somewhere between 60 and 90%. NSE has been a relevant biomarker for patients with high-grade tumors, particularly lung and gastrointestinal tract tumors. Serotonin and the breakdown product urinary 5-hydroxyindoleacetic acid (U-5-HIAA) is still an important marker for diagnosing and follow-up of SI NETs. Recently, 5-HIAA in plasma has been analyzed by high-performance liquid chromatography and fluorometric detection and has shown good agreement with U-5-HIAA analysis. In the future, we will see new tests including circulating tumor cells, circulating DNA and mRNA. Recently, a NET test has been developed analyzing gene transcripts in circulating blood. Preliminary data indicate high sensitivity and specificity for NETs. However, its precise role has to be validated in prospective randomized controlled trials which are ongoing right now.

Additional malignancies in patients with neuroendocrine tumours: analysis of the SwissNET registry

PRINCIPLES

Neuroendocrine neoplasms (NENs) are believed to be associated with an increased risk for additional malignancies (AMs). We aimed to (1) assess the occurrence of AM in NEN patients (2) investigate the characteristics and temporal relationship of NEN patients with and without AM.

METHODS

The SwissNET registry has prospectively documented patients with NEN since 2008, covering the entire area of Switzerland. Clinical characteristics, functionality, location and histology of NEN as well as survival of all consecutive patients were retrieved. The characteristics of the AM (location, histology, time point of diagnosis in relation to diagnosis of NEN) were extracted.

RESULTS

Out of 934 patients, 193 patients (21%) presented with AMs. There was no statistically significant difference with regard to location, functionality and grading (G1-G3) between the NEN patients with and without AM. AMs were diagnosed synchronously (±3 months), before (>-3 months) and after (>+3 months) diagnosis of NEN in 82 (42%), 96 (50%) and 13 (7%) patients, respectively. Location of NEN correlated with the anatomical origin of the AM. Age- and gender- corrected survival was not significantly different between NEN patients with and without AM.

CONCLUSION

The prevalence of AM in NEN is high. The comparable characteristics with regard to functionality and grading in the NEN cohorts with and without AM and the similar location of AM and NEN suggest a selection bias towards frequent imaging procedures in NEN patients with AM.

mTOR inhibitors response and mTOR pathway in pancreatic neuroendocrine tumors

Medical therapy of pancreatic neuroendocrine tumors (P-NET) may take advantage of Everolimus treatment. However, the extent of therapeutic response cannot be predicted. This study was aimed to identify the possible predictive markers of response to Everolimus in P-NET. We found that Everolimus reduced the cell viability and induced apoptosis in primary cultures of 6 P-NET (P-NET-R), where the proliferative and antiapoptotic effects of IGF1 were blocked by Everolimus. On the contrary, 14 P-NET primary cultures (P-NET-NR) were resistant to Everolimus and IGF1, suggesting an involvement of PI3K/AKT/mTOR pathway in the mechanism of resistance. The response to Everolimus in vitro was associated with an active AKT/mTOR pathway and seemed to be associated with a greater clinical aggressiveness. In addition, a patient sensitive to Everolimus in vitro was sensitive to this drug in vivo also and showed a positive p-AKT immunohistochemistry (IHC) at tissue level. Similarly, a patient resistant to Everolimus treatment after surgery was not sensitive to the drug in vitro and had a negative p-AKT IHC staining. Therefore, present data confirm that P-NET primary cultures may be considered a model for testing medical treatment efficacy and that IHC characterization of p-AKT might help in identifying human P-NET who can benefit from Everolimus treatment. These data encourage conducting a prospective multicenter study involving different groups of P-NET patients treated with Everolimus.

PTEN alterations of the stromal cells characterise an aggressive subpopulation of pancreatic cancer with enhanced metastatic potential

BACKGROUND

Neoplastic stroma is believed to influence tumour progression. Here, we examine phosphatase and tensin homolog deleted on chromosome ten (PTEN) status in the tumour microenvironment of pancreatic ductal adenocarcinoma (PDAC) focussing especially at the stromal cells.

METHODS

We asses PTEN at protein, messenger RNA and DNA level using a well-characterised PDAC cohort (n = 117). miR-21, known to target PTEN, is assessed after RNA extraction from different laser-capture-microdissected cell populations, including cancer cells and juxta-tumoural and tumour-remote stroma.

RESULTS

PTEN deletion was the most frequent cause of PTEN protein loss in PDAC cells (71%) and correlated with vascular invasion (p = 0.0176) and decreased overall survival (p = 0.0127). Concomitant PTEN protein loss in tumour and juxta-tumoural stroma, found in 21.4% of PDACs, correlated with increased distant metastasis (p = 0.0045). Stromal cells with PTEN protein loss frequently showed PTEN genetic aberrations, including hemizygous PTEN deletion (46.6%) or chromosome 10 monosomy (40%). No alterations were found in the tumour-remote stroma. miR-21 was overexpressed by cancer- and juxta-tumoural stromal cells, in some cases without simultaneous PTEN gene alterations. No PTEN mutations or promoter methylation were detected.

CONCLUSIONS

We find various mechanisms of PTEN protein loss in the different tumour cell populations, including allelic PTEN deletions, gross chromosomal 10 aberrations and altered miR-21 expression. PTEN deletion is a major cause of PTEN protein loss in PDAC and correlates with aggressive characteristics and worse outcome. PTEN protein loss in juxta-tumoural stromal cells is mostly due to PTEN haplo-insufficiency and characterises a subgroup of PDACs with enhanced metastatic potential. In the tumour microenvironment of the invasive front, PTEN silencing by miR-21 in cancer and surrounding stromal cells acts not only cooperatively but also independently of the genetic aberrations to precipitate PTEN protein loss and promote further tumour growth.

New Genetics and Genomic Data on Pancreatic Neuroendocrine Tumors: Implications for Diagnosis, Treatment, and Targeted Therapies

The recent findings on the roles of death-associated protein 6/α-thalassemia/mental retardation X-linked (DAXX/ATRX) in the development of pancreatic neuroendocrine tumors (PanNETs) have led to major advances in the molecular understanding of these rare tumors and open up completely new therapeutic windows. This overview aims at giving a simplified view on these findings and their possible therapeutic implications. The importance of epigenetic changes in PanNET is also underlined by recent findings of a cross-species study on microRNA (miRNA) and messenger RNA (mRNA) profiles in PanNETs.