Pancreatic endocrine tumors

Update in the management of gastroenteropancreatic neuroendocrine tumors

Neuroendocrine neoplasms are a diverse group of neoplasms that can occur in various areas throughout the body. Well-differentiated neuroendocrine tumors (NETs) most often arise in the gastrointestinal tract, termed gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Although GEP-NETs are still uncommon, their incidence and prevalence have been steadily increasing over the past decades. The primary treatment for GEP-NETs is surgery, which offers the best chance for a cure. However, because GEP-NETs are often slow-growing and do not cause symptoms until they have spread widely, curative surgery is not always an option. Significant advances have been made in systemic and locoregional treatment options in recent years, including peptide-receptor radionuclide therapy with α and β emitters, somatostatin analogs, chemotherapy, and targeted molecular therapies.

Neoplastic Progression in Neuroendocrine Neoplasms of the Pancreas

CONTEXT.—

Pancreatic neuroendocrine neoplasms (PanNENs) represent a heterogeneous group of epithelial tumors of the pancreas showing neuroendocrine differentiation. These neoplasms are classified into well-differentiated pancreatic neuroendocrine tumors (PanNETs), which include G1, G2, and G3 tumors, and poorly differentiated pancreatic neuroendocrine carcinomas (PanNECs), which are G3 by definition. This classification mirrors clinical, histologic, and behavioral differences and is also supported by robust molecular evidence.

OBJECTIVE.—

To summarize and discuss the state of the art regarding neoplastic progression of PanNENs. A better comprehension of the mechanisms underpinning neoplastic evolution and progression of these neoplasms may open new horizons for expanding biologic knowledge and ultimately for addressing new therapeutic strategies for patients with PanNENs.

DATA SOURCES.—

Literature review of published studies and the authors' own work.

CONCLUSIONS.—

PanNETs can be seen as a unique category, where G1-G2 tumors may progress to G3 tumors mainly driven by DAXX/ATRX mutations and alternative lengthening of telomeres. Conversely, PanNECs display totally different histomolecular features more closely related to pancreatic ductal adenocarcinoma, including TP53 and Rb alterations. They seem to derive from a nonneuroendocrine cell of origin. Even the study of PanNEN precursor lesions corroborates the rationale of considering PanNETs and PanNECs as separate and distinct entities. Improving the knowledge regarding this dichotomous distinction, which guides tumor evolution and progression, will represent a critical basis for PanNEN precision oncology.

Identification of fibroblast-related genes based on single-cell and machine learning to predict the prognosis and endocrine metabolism of pancreatic cancer

Background

Single-cell sequencing technology has become an indispensable tool in tumor mechanism and heterogeneity studies. Pancreatic adenocarcinoma (PAAD) lacks early specific symptoms, and comprehensive bioinformatics analysis for PAAD contributes to the developmental mechanisms.

Methods

We performed dimensionality reduction analysis on the single-cell sequencing data GSE165399 of PAAD to obtain the specific cell clusters. We then obtained cell cluster-associated gene modules by weighted co-expression network analysis and identified tumorigenesis-associated cell clusters and gene modules in PAAD by trajectory analysis. Tumor-associated genes of PAAD were intersected with cell cluster marker genes and within the signature module to obtain genes associated with PAAD occurrence to construct a prognostic risk assessment tool by the COX model. The performance of the model was assessed by the Kaplan-Meier (K-M) curve and the receiver operating characteristic (ROC) curve. The score of endocrine pathways was assessed by ssGSEA analysis.

Results

The PAAD single-cell dataset GSE165399 was filtered and downscaled, and finally, 17 cell subgroups were filtered and 17 cell clusters were labeled. WGCNA analysis revealed that the brown module was most associated with tumorigenesis. Among them, the brown module was significantly associated with C11 and C14 cell clusters. C11 and C14 cell clusters belonged to fibroblast and circulating fetal cells, respectively, and trajectory analysis showed low heterogeneity for fibroblast and extremely high heterogeneity for circulating fetal cells. Next, through differential analysis, we found that genes within the C11 cluster were highly associated with tumorigenesis. Finally, we constructed the RiskScore system, and K-M curves and ROC curves revealed that RiskScore possessed objective clinical prognostic potential and demonstrated consistent robustness in multiple datasets. The low-risk group presented a higher endocrine metabolism and lower immune infiltrate state.

Conclusion

We identified prognostic models consisting of APOL1, BHLHE40, CLMP, GNG12, LOX, LY6E, MYL12B, RND3, SOX4, and RiskScore showed promising clinical value. RiskScore possibly carries a credible clinical prognostic potential for PAAD.

An update on genetically engineered mouse models of pancreatic neuroendocrine neoplasms

Pancreatic neuroendocrine neoplasms (PanNENs) are rare and clinically challenging entities. At the molecular level, PanNENs' genetic profile is well characterized, but there is limited knowledge regarding the contribution of the newly identified genes to tumor initiation and progression. Genetically engineered mouse models (GEMMs) are the most versatile tool for studying the plethora of genetic variations influencing PanNENs' etiopathogenesis and behavior over time. In this review, we present the state of the art of the most relevant PanNEN GEMMs available and correlate their findings with the human neoplasms' counterparts. We discuss the historic GEMMs as the most used and with higher translational utility models. GEMMs with Men1 and glucagon receptor gene germline alterations stand out as the most faithful models in recapitulating human disease; RIP-Tag models are unique models of early-onset, highly vascularized, invasive carcinomas. We also include a section of the most recent GEMMs that evaluate pathways related to cell cycle and apoptosis, Pi3k/Akt/mTOR, and Atrx/Daxx. For the latter, their tumorigenic effect is heterogeneous. In particular, for Atrx/Daxx, we will require more in-depth studies to evaluate their contribution; even though they are prevalent genetic events in PanNENs, they have low/inexistent tumorigenic capacity per se in GEMMs. Researchers planning to use GEMMs can find a road map of the main clinical features in this review, presented as a guide that summarizes the chief milestones achieved. We identify pitfalls to overcome, concerning the novel designs and standardization of results, so that future models can replicate human disease more closely.

Surgical Outcomes and Prognostic Factors of G3 Pancreatic Neuroendocrine Carcinomas: A Consecutive Analysis Based on Previous Study Results

In 2017, the World Health Organization (WHO) officially defined pancreatic neuroendocrine neoplasms into well-differentiated tumors, namely G1/G2/G3 pancreatic neuroendocrine tumors, and poorly differentiated carcinomas referring to G3 pancreatic neuroendocrine carcinomas (p-NECs). However, the surgical outcomes and prognostic factors of G3 p-NECs are still unclear. Methods: We retrospectively collected and analyzed the data of eligible patients with G3 p-NECs defined by the WHO 2017 grading classification. Results: We eventually identified 120 patients with G3 p-NECs, including 72 females and 48 males, with a median age of 53 y. The 3-year overall survival (OS) of G3 p-NECs by Kaplan−Meier method was 37.3%. The 3-year OS for functional G3 p-NECs was 57.4%, which was statistically longer than 23.0% of non-functional ones (p = 0.002). Patients with surgical resection presented a significantly better 3-year OS than those with palliative operation (43.3% vs. 13.1%; p < 0.001). The 3-year OS for Stage Ⅰ, Stage Ⅱ, Stage Ⅲ, and Stage Ⅳ was 87.1%, 56.5%, 12.9%, and not applicable, respectively (p < 0.001). We demonstrated in a Cox regression model that palliative operation (p = 0.013), vascular infiltration (p = 0.039), lymph node involvement (p = 0.024), and distant metastasis (p = 0.016) were independent predictors of poor outcome for patients with surgically treated G3 p-NECs. Conclusion: Our data in the present analysis indicated that patients with G3 p-NECs could significantly benefit from surgical resection. Meanwhile, vascular infiltration, lymph node involvement, and distant metastasis were independent predictors of poor outcome for these patients.

Pancreatic neuroendocrine neoplasms: survival trend analysis of a comprehensive center

Objectives

Therapeutic options for pancreatic neuroendocrine neoplasia (Pan-NEN) have increased over the last decade. We aim to understand the evolution of the prognosis of patients with diagnosis of Pan-NEN within a 12-year period, considering the implementation of new treatments.

Methods

This study is a retrospective cohort study of patients diagnosed with Pan-NENs between 2006 and 2017. Survival outcome estimates were calculated by Kaplan-Meier method. The impact of baseline clinicopathological characteristics on survival was explored with the use of Cox proportional hazard model.

Results

Of the 97 patients, 77 (79.9%) had well-differentiated neuroendocrine tumor (NET) according to WHO 2010 classification, and 52 (53.6%) had localized or locoregional disease. There were no differences between clinicopathological characteristics and survival outcomes when comparing patients diagnosed between 2006-2011 and 2012-2017. Neuroendocrine carcinoma - HR 2.76, 95% CI 1.17-6.55 - and stages III and IV at diagnosis were independent poor prognostic factors - HR 6.02, 95% CI 2.22-16.33 and HR 6.93, 95% CI 2.94-16.32, respectively.

Conclusions

The new therapeutic approaches did not induce better survival outcomes on Pan-NEN in recent years. This is possibly due to the indolent nature of NET grades 1 and 2, even metastatic, allowing patients to be submitted to new target therapies along their disease course.

Cytopathological characteristics of solitary fibrous tumour involving the pancreas by fine needle aspiration: Making an accurate preoperative diagnosis in an uncommon location

BACKGROUND

Solitary fibrous tumour (SFT) is a unique mesenchymal neoplasm with classic features on histology and is characterised by the NAB2-STAT6 gene fusion. There are rare reports of SFTs with pancreatic involvement and only two cases in the literature reporting its features by preoperative fine needle aspiration (FNA). Herein, we characterise the cytomorphological features of four SFTs involving the pancreas by FNA to establish a preoperative diagnostic approach.

METHODS

The anatomic pathology archives of two academic medical centres were searched to identify patients with a pancreatic FNA cytology specimen and a confirmed diagnosis of SFT by surgical resection. The clinical history, pathological diagnosis, cytomorphological findings, and results of immunohistochemistry (IHC) were reviewed.

RESULTS

Four SFTs were identified from four patients with a median age of 59 years. The morphological features were variable but most frequently showed a bland spindled-to-epithelioid proliferation in fragments and single cells with small, oval, elongated, and hypochromatic nuclei in a haphazard arrangement with or without dense collagen. One tumour presented with a concurrent metastasis and showed a pure epithelioid component with necrosis and enlarged, hyperchromatic nuclei with conspicuous nucleoli and scattered mitoses. IHC was necessary for all diagnoses which were confirmed by surgical resection.

CONCLUSIONS

SFTs with pancreatic involvement are rare, and non-specific features and tumour heterogeneity can pose a diagnostic challenge on FNA; however, IHC can be used to make a definitive diagnosis. As a result, FNA is a simple, safe, cost-effective, and accurate approach that can be used to diagnose SFT in the pancreas.

Insulinoma-associated protein 1 (INSM1) is a robust marker for identifying and grading pancreatic neuroendocrine tumors

BACKGROUND

Pancreatic neuroendocrine tumor (PNET) is a diagnostic challenge with limited samples in not only identification but grading. Prior studies have shown insulinoma-associated protein 1 (INSM1) to be a robust marker in identifying PNETs from other solid pancreatic tumors on resection specimens. In this study, we investigated the utility of INSM1 not only for identifying PNETs but also for grading in cell blocks (CBs) and surgical resections (SRs).

METHODS

A search for PNET cases between 2000 and 2019 identified 55 samples (26 CBs and 29 SRs) that were further separated into high (2 CBs, 3 SRs), intermediate (4 CBs, 7 SRs), and low (20 CBs, 19 SRs) grades based on their final pathology report and Ki-67 level. Immunohistochemical (IHC) staining for INSM1 (C-8, Santa Cruz Biotechnology [1:100]) was performed and quantified using an H score of 0 to 300. Non-PNET solid pancreatic tumors were compared and included acinar cell carcinoma, solid pseudopapillary neoplasm, and ductal adenocarcinoma.

RESULTS

All 55 cases of PNET demonstrated nuclear INSM1 staining. The average H scores for INSM1 staining of PNET were 254 and 252 in CB and SR, respectively. The H scores decreased with increasing tumor grade, with low-grade (G1), intermediate-grade (G2), and high-grade (G3) tumors showing average INSM1 H scores of 229 and 253, 266 and 253, and 30 and 33 in both CB and SR, respectively.

CONCLUSION

IHC with INSM1 plays a role in identifying and potentially grading PNETs.

Pancreatic cancer incidence trends: evidence from the Surveillance, Epidemiology and End Results (SEER) population-based data

Background

Annual pancreatic cancer incidence rates have been increasing. We examine pancreatic cancer incidence trends by demographics and histologic type.

Methods

Data from the Surveillance, Epidemiology and End Results (SEER) registries were available to assess temporal trends and pancreatic cancer rates from 1974 to 2013.

Results

Pancreatic cancer incidence rates declined between the 1970s and 1990s but increased from 1994 to 2013 among White males. Among non-Hispanic White and Hispanic males, the annual percent change (APC) in incidence between 1992 and 2013 was 0.84% and 0.73%, respectively. Rates also rose among White non-Hispanic, Hispanic and Asian females (APC = 0.81%, 0.56% and 1.23%, respectively) and even more rapidly among females aged 25-34 years (APC > 2.5%). Rates among Black males and females remained unchanged, but higher compared with the other racial/ethnic groups. By histologic type, the increases were greatest for non-secretory endocrine cancers ( > 6%), followed by ductal adenocarcinomas (∼5%) and adenocarcinoma, NOS (∼1.4%)-the largest histologic subgroup of pancreatic cancer. Rates for mucinous adenocarcinomas and poorly specified pancreatic cancer decreased. Overall, incidence rates during 2000-13 were higher among males than females [MF incidence rate ratio (IRR) = 1.28]. The IRR was >1.00 at all ages ≥ 35, but rates among females were higher at younger ages (IRRs 15-24: 0.66, 25-34: 0.81). The MF IRRs for most of the histologic types were elevated among males apart from solid pseudopapillary adenocarcinoma and cystic carcinomas (IRR = 0.22, confidence interval: 0.14-0.34 and 0.52, 0.41-0.65, respectively).

Conclusion

Pancreatic cancer has been increasing overall, but patterns differ by demographic group and histologic type. Many of the trends parallel changing prevalence of lifestyle risk factors such as smoking, overweight and obesity, and diabetes in the USA, particularly for pancreatic adenocarcinoma, and improved diagnosis methods during the past 40 years.

Neoplasms of the Neuroendocrine Pancreas: An Update in the Classification, Definition, and Molecular Genetic Advances

This review focuses on discussing the main modifications of the recently published 2017 WHO Classification of Neoplasms of the Neuroendocrine Pancreas (panNEN). Recent updates separate pancreatic neuroendocrine tumors into 2 broad categories: well-differentiated pancreatic neuroendocrine tumors (panNET) and poorly differentiated pancreatic neuroendocrine carcinoma (panNEC), and incorporates a new subcategory of "well-differentiated high-grade NET (G3)" to the well-differentiated NET category. This new classification algorithm aims to improve the prediction of clinical outcomes and survival and help clinicians select better therapeutic strategies for patient care and management. In addition, these neuroendocrine neoplasms are capable of producing large quantity of hormones leading to clinical hormone hypersecretion syndromes. These functioning tumors include, insulinomas, glucagonomas, somatostatinomas, gastrinomas, VIPomas, serotonin-producing tumors, and ACTH-producing tumors. Although most panNENs arise as sporadic diseases, a subset of these heterogeneous tumors present as parts on inherited genetic syndromes, such as multiple endocrine neoplasia type 1, von Hippel-Lindau, neurofibromatosis type 1, tuberous sclerosis, and glucagon cell hyperplasia and neoplasia syndromes. Characteristic clinical and morphologic findings for certain functioning and syndromic panNENs should alert both pathologists and clinicians as appropriate patient management and possible genetic counseling may be necessary.

Accuracy of grading pancreatic neuroendocrine neoplasms with Ki-67 index in fine-needle aspiration cellblock material

OBJECTIVE

The aim of this study was to assess the preoperative tumour grade of pancreatic neuroendocrine neoplasms (panNENs) by determining the Ki-67 index in endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) material and to correlate the preoperative tumour grade with the postoperative tumour grade in surgical specimens.

METHODS

We performed a retrospective review of the institutional pathology database over a 10-year period (2007-2017) to identify all cases of panNENs with corresponding preoperative EUS-FNA cytological material and surgical specimens. Fifteen cases with adequate EUS-FNA material (more than 400 tumour cells on cellblock) were identified. The cytological and histological samples were graded based on the mitotic rate and the Ki-67 index in accordance with the 2017 World Health Organisation grading system for panNENs. The tumour grades determined on EUS-FNA cellblock material were compared with the histological tumour grades.

RESULTS

Mean age at diagnosis was 64.8 ± 12.7 years (range, 38-85 years). The grading scores assigned to the cytological and histological samples were concordant in all 15 (100%) cases. Of those, two (13%) cases were scored as grade 1, nine (60%) cases as grade 2 and four (27%) cases as grade 3 tumours.

CONCLUSION

Our study shows that tumour grade in patients with PanNENs can be reliably determined by assessing the Ki-67 index in EUS-FNA specimens based on the 2017 World Health Organisation classification and grading system.

Gastroenteropancreatic Neuroendocrine Tumors

Neuroendocrine tumors (NETs) are heterogeneous malignancies arising from the diffuse neuroendocrine system. They frequently originate in the gastroenteropancreatic (GEP) tract and the bronchopulmonary tree, and their incidence has steadily increased in the last 3 decades. Fundamental biologic and genomic differences underlie the clinical heterogeneity of NETs, and distinct molecular features characterize NETs of different grades and different primary sites. Although surgery remains the cornerstone of treatment for localized tumors, systemic treatment options for patients with metastatic NETs have expanded considerably. Somatostatin analogs have demonstrated both antisecretory and antitumor efficacy. Peptide receptor radionuclide therapy with lutetium-177 dotatate (¹⁷⁷ Lu-DOTATATE) has been approved for advanced GEP-NETs. The antitumor activity of everolimus has been demonstrated across a wide spectrum of NETs, and the antiangiogenic agent sunitinib has been approved for pancreatic NETs (pNETs). Chemotherapy with temozolomide and capecitabine has recently demonstrated an unprecedented prolongation of progression-free survival in a randomized trial of pNETs. Multiple retrospective series have reported the efficacy of liver-directed therapies both for palliating symptoms of hormone excess and for controlling tumor growth. Telotristat, an oral inhibitor of tryptophan hydroxylase, has been shown to reduce diarrhea in patients with carcinoid syndrome. Defining the therapeutic algorithm and identifying biomarkers predictive of response to treatments are among the main priorities for the next decade of research in the NET field.

Insulinoma presenting with post-prandial hypoglycaemia following fundoplication

Insulinomas are rare neuroendocrine tumours that classically present with fasting hypoglycaemia. This case report discusses an uncommon and challenging case of insulinoma soon after upper gastrointestinal surgery. A 63-year-old man presented with 6 months of post-prandial hypoglycaemia beginning after a laparoscopic revision of Toupet fundoplication. Hyperinsulinaemic hypoglycaemia was confirmed during a spontaneous episode and in a mixed-meal test. Localisation studies including magnetic resonance imaging (MRI), endoscopic ultrasound (EUS) and gallium dotatate positron emission tomography (⁶⁸Ga Dotatate PET) were consistent with a small insulinoma in the mid-body of the pancreas. The lesion was excised and histopathology was confirmed a localised well-differentiated neuroendocrine pancreatic neoplasm. There have been no significant episodes of hypoglycaemia since. This case highlights several key points. Insulinoma should be sought in proven post-prandial hyperinsulinaemic hypoglycaemia - even in the absence of fasting hypoglycaemia. The use of nuclear imaging targeting somatostatin and GLP1 receptors has improved accuracy of localisation. Despite these advances, accurate surgical resection can remain challenging.

Learning points

Hypoglycaemia is defined by Whipple's triad and can be provoked by fasting or mixed-meal tests.Although uncommon, insulinomas can present with post-prandial hypoglycaemia.In hypoglycaemia following gastrointestinal surgery (i.e. bariatric surgery or less commonly Nissen fundoplication) dumping syndrome or non-insulinoma pancreatogenous hypoglycaemia syndrome (NIPHS) should be considered.Improved imaging techniques including MRI, endoscopic ultrasound and functional nuclear medicine scans aid localisation of insulinomas.Despite advances in imaging and surgical techniques, accurate resection of insulinomas remains challenging.

Pancreatic Neuroendocrine Tumors Complicated by Sinistral Portal Hypertension: Insights into Pathogenesis

Purpose: To investigate the association between pancreatic neuroendocrine tumors (panNETs) and sinistral portal hypertension (SPH) and provide insights into the pathogenesis.

Methods: A retrospective review of panNETs was conducted from our institution for 12 years. Medical imaging findings were analyzed to determine any association with splenic vein thrombosis (SVT) at diagnosis. The cases were further selected based on the criteria for SPH, namely, (1) presence of SVT, (2) gastric varices, (3) patent portal vein, and (4) normal liver function tests.

Results: There were 61 patients with panNETs and 8 (8/61) had SVT and gastric varices at diagnosis. Four (4/8) met the strict criteria for SPH while the other four had more conventional portal hypertension. The four with SPH had large tumors located in the tail with splenic vein invasion and three of four presented with bleeding gastric varices. All four patients underwent surgical resection. Mean follow-up was 8.5 years and the hematemesis never recurred. The other four patients (four of eight) with gastric varices had unresectable disease and all died after a mean survival of 29 months.

Conclusion: PanNETs appear to be more commonly associated with SVT and SPH compared with other tumors. This could be related to their relatively indolent nature and their intrinsic vascularity. From a surgical viewpoint, the decision to operate depends on many factors including but not limited to the size/stage, grade, and functionality of the tumor and comorbidities. These considerations notwithstanding, the association between panNETs and SPH suggests that there is benefit in timely resection of panNETs located in the tail.

Pancreatic Imaging

Imaging of the endocrine pancreas is dominated by neuroendocrine tumors, a diverse category of neoplasms that may or may not cause symptoms from hormone hypersecretion. These tumors may also be evidence of several different genetic syndromes. Understanding the usefulness of different imaging modalities and entities that simulate neuroendocrine tumors is key for both radiologists and referring physicians.

Combined treatment with artesunate and bromocriptine has synergistic anticancer effects in pituitary adenoma cell lines

Prolactinomas are the most prevalent functional pituitary adenomas. The preferred treatments for prolactinomas are dopamine agonists (DAs) such as bromocriptine (BRC), but DAs still have the challenges of tumor recurrence and drug resistance. This study demonstrates that the synergy of function and mechanism between artesunate (ART) and BRC inhibits prolactinoma cell growth in vitro. We found that low-dose ART combined with BRC synergistically inhibited the growth of GH3 and MMQ cell lines, caused cell death, attenuated cell migration and invasion, and suppressed the expression of extracellular prolactin. The induction of apoptosis after co-treatment was confirmed by immunofluorescent staining, assessment of caspase-3 protein expression, and flow cytometry. Expression of miR-200c, a carcinogenic factor in pituitary adenoma, was reduced following co-treatment with ART and BRC. This was accompanied by increased expression of the antitumor factor Pten. Transfection experiments with miR-200c analogs and inhibitors confirmed that miR-200c expression was inversely associated with Pten expression. We suggest that ART and BRC used in combination exert synergistic apoptotic and antitumor effects by suppressing miR-200c and stimulating Pten expression.

Prognostic relevance of UCH-L1 and α-internexin in pancreatic neuroendocrine tumors

Prognostic biomarkers for the pancreatic neuroendocrine tumors are needed. Proteomic study on insulinoma has been rarely reported. We identified the differential expression of proteins between insulinoma and their paired tissues by proteomic analysis, and evaluated the prognostic significance of specific proteins in pancreatic neuroendocrine tumors including insulinoma. The differential expression of select proteins was validated in more than 300 tumors using immunohistochemical staining and western blot. Methylation of UCH-L1 promoter in tumors was examined by methylation specific PCR and validated by sequencing. The concurrent expression of UCH-L1 and α-internexin was correlated with the prognosis in 2 independent collectives of patients with tumors. Sixty-two and 219 proteins were significantly down-regulated and up-regulated in insulinomas, respectively. Demethylation of UCH-L1 promoter was associated with UCH-L1 expression in tumors (p = 0.002). The concurrent expression of UCH-L1 and α-internexin in pancreatic neuroendocrine tumors was significantly associated with better overall survival and disease-free survival in the combination of both cohorts (log rank p = 3.90 × 10⁻⁴ and p = 3.75 × 10⁻⁵, respectively) and in each of cohorts. The prognostic value of both proteins was also validated in patients with stage II and III tumors (p = 0.017 and p = 0.006, respectively). The proteins UCH-L1 and α-internexin could be independent prognostic biomarkers of pancreatic neuroendocrine tumors.

Translational research in neuroendocrine tumors: pitfalls and opportunities

Interest in research on neuroendocrine tumors (NETs) has grown in the past 10 years, coinciding with improvements in our understanding of the molecular pathogenesis of NETs. In addition, NETs have become one of the most exciting settings for drug development. Two targeted agents for the management of advanced pancreatic NETs have been approved, but the development of targeted agents for NETs is limited by problems with both patient selection and demonstration of activity. In this review, we analyze these limitations and discuss ways to increase the predictive value of preclinical models for target discovery and drug development. The role of translational research and 'omics' methodologies is emphasized, with the final aim of developing personalized medicine. Because NETs usually grow slowly and metastatic tumors are found at easily accessible locations, and owing to improvements in techniques for liquid biopsies, NETs provide a unique opportunity to obtain tumor samples at all stages of the evolution of the disease and to adapt treatment to changes in tumor biology. Combining clinical and translational research is essential to achieve progress in the NET field. Slow growth and genetic stability limit and challenge both the availability and further development of preclinical models of NETs, one of the most crucial unmet research needs in the field. Finally, we suggest some useful approaches for improving clinical drug development for NETs: moving from classical RECIST-based response end points to survival parameters; searching for different criteria to define response rates (for example, antiangiogenic effects and metabolic responses); implementing randomized phase II studies to avoid single-arm phase II studies that produce limited data on drug efficacy; and using predictive biomarkers for patient selection.

Dynamic computed tomography is useful for prediction of pathological grade in pancreatic neuroendocrine neoplasm

BACKGROUND AND AIM

Pathological grading is important in defining the therapeutic strategy in pancreatic neuroendocrine neoplasm (PNEN) but is difficult for unresectable cases. Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) is useful in the diagnosis of PNEN, but its usefulness for pathological grading is not well established. No studies have examined the diagnostic ability of dynamic computed tomography (CT) for pathological grading of PNEN. We investigated the usefulness of EUS-FNA and dynamic CT in the diagnosis and pathological grading of PNEN.

METHODS

In this retrospective study, 39 PNEN patients finally diagnosed via EUS-FNA and/or surgical resection underwent dynamic CT. Pathological samples were diagnosed based on WHO2010; staging was based on the European Neuroendocrine Tumor Society classification. The proportion of the quantification value in the tumor to the pancreatic parenchyma in arterial phase was defined as the CT ratio. Immunohistochemical staining with CD31 was performed to evaluate microvessel density (MVD). We evaluated the relationship between pathological grade, CT ratio, and MVD.

RESULTS

By using EUS-FNA, 35 of 39 (90%) cases were diagnosed as PNEN. As for pathological grade, 15 of 35 (43%) cases could be identified correctly. CT ratio could predict pathological Grade 3 disease. The sensitivity, specificity, and diagnostic accuracy were 100%, 94%, and 95%. MVD was significantly correlated with CT ratio (r = 0.83, P < 0.0001) and pathological grade (P = 0.0074).

CONCLUSIONS

Computed tomography ratio has a relationship with pathological grade in PNEN, which would help decide therapeutic strategy in unresectable cases and cases in which pathological grading is difficult.

Expression of erythropoietin and neuroendocrine markers in clear cell renal cell carcinoma

The aim of the study was to investigate the expression of erythropoietin and neuroendocrine markers in clear cell renal cell carcinoma (CCRCC). We retrospectively reviewed the medical records and re-evaluated histopathological specimens of 33 patients with CCRCC and compared with those of 11 cases of non-CCRCC. All patients were treated with a partial or radical nephrectomy at St. Olavs Hospital, Trondheim University Hospital, between 2010 and 2016. Thirty-three patients who were diagnosed with CCRCC had a total of 35 tumours, where 34 of the tumours were CCRCC and one was papillary adenoma. Thirty-three (97%) of 34 CCRCCs were positive for erythropoietin, and the same 33 (97%) tumours demonstrated strong expression for neuron-specific enolase (NSE). Two (6%) of 34 CCRCCs had a positive reaction for synaptophysin, and three (9%) of 34 were positive for CD56. Erythropoietin and NSE were negative in non-CCRCCs, and chromogranin A was negative in all tumours. The above findings suggest that there is a strong association between CCRCC and the expression of erythropoietin and NSE.

Reliability of Ki-67 Determination in FNA Samples for Grading Pancreatic Neuroendocrine Tumors

Neuroendocrine pancreatic tumors (PanNETs) are graded on the basis of their proliferative activity. Cytological samples are commonly the only samples available, but the determination of Ki-67 in cytology and its reliability as a measure of tumor mitotic activity is not well settled. We have retrospectively reviewed all the cases of FNA under EUS control of PanNETs in a 10-year period (2006-2016) in the Hospital Clínico San Carlos (Madrid). We identified 10 PanNET cases with histological correlation. Median age was 49.4 years and the patients were mainly women. PanNETs were located more frequently in the tail of the pancreas, with a median size of 33.8 mm. None of our cases was a grade 3 tumor. The seven grade 1 tumors confirmed in histology had consistent Ki-67 in cytology. In three cases (30 %), there were discrepancies between the Ki-67 index measured in cytology and histology, and the differences ranged from 2 to 15 %; all these cases were grade 2 tumors in histology and were graded as grade 1 tumors in FNA material. Our results are consistent with previous studies which showed understaging when tumor grade was assessed in cytological samples, mainly in G2 tumors. Previous literature has shown that Ki-67 assessment in EUS-FNA samples is a useful tool to rule out G3 tumors, but can be problematic for distinguishing G1 and G2 tumors.

Pancreatic neuroendocrine tumor and solid-pseudopapillary neoplasm: Key immunohistochemical profiles for differential diagnosis

AIM

To reveal better diagnostic markers for differentiating neuroendocrine tumor (NET) from solid-pseudopapillary neoplasm (SPN), focusing primarily on immunohistochemical analysis.

METHODS

We reviewed 30 pancreatic surgical specimens of NET (24 cases) and SPN (6 cases). We carried out comprehensive immunohistochemical profiling using 9 markers: Synaptophysin, chromogranin A, pan-cytokeratin, E-cadherin, progesterone receptor, vimentin, α-1-antitrypsin, CD10, and β-catenin.

RESULTS

E-cadherin staining in NETs, and nuclear labeling of β-catenin in SPNs were the most sensitive and specific markers. Dot-like staining of chromogranin A might indicate the possibility of SPNs rather than NETs. The other six markers were not useful because their expression overlapped widely between NETs and SPNs. Moreover, two cases that had been initially diagnosed as NETs on the basis of their morphological features, demonstrated SPN-like immunohistochemical profiles. Careful diagnosis is crucial as we actually found two confusing cases showing disagreement between the tumor morphology and immunohistochemical profiles.

CONCLUSION

E-cadherin, chromogranin A, and β-catenin were the most useful markers which should be employed for differentiating between NET and SPN.

Grading pancreatic neuroendocrine neoplasms by Ki-67 staining on cytology cell blocks: manual count and digital image analysis of 58 cases

INTRODUCTION

Controversy remains as to whether Ki-67 labeling on endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) cell blocks (CBs) can be used to grade pancreatic neuroendocrine neoplasms (PanNENs) reliably and what would be the best methodology for doing so.

MATERIALS AND METHODS

A retrospective search identified cases with both EUS-FNA and correlating surgical pathology (SP) available. 58 CBs (>100 tumor cells) were identified. Ki-67 labeling on CB was counted using both manual count (MC) and digital image analysis (DIA, ImmunoRatio software). The grades determined on CB were compared with those on corresponding SP reports (kappa statistics). The correct grading rates between MC and DIA were compared (McNemar's test). Total tumor cell number (TTCN, cutoffs: 500 and 2000) was used as a stratification factor (chi-square tests for trend).

RESULTS

Of 58 cases, the SP grade distribution was 31 grade 1, 23 grade 2, and 4 grade 3. Overall, the grading concordance of CB MC and SP was higher than that of CB DIA and SP (McNemar's P-value = 0.022). Compared with SP, CB MC correctly graded 69% (40 of 58) [κ = 0.44 (95% CI: 0.21, 0.66)]; CB DIA correctly graded 55% (32 of 58) [κ = 0.19 (95% CI: 0.04, 0.42)]. Grade 1 tumors had the highest concordance. Although the correct grading rate improved as TTCN increased, no statistical significance was found.

CONCLUSION

Although Ki-67 labeling on CB can be used to grade PanNENs, limitation exists, particularly for grade 2 tumors. The method of counting makes a difference: MC is more accurate than DIA. The major reasons of discordance include non-tumor cell contamination and insufficient sampling.

Von Hippel-Lindau Disease

Von Hippel-Lindau disease is an autosomal dominant syndrome which occurs secondary to germline mutations in the VHL tumor suppressor gene, located on chromosome 3. Clinically von Hippel-Lindau disease is characterized by an increased risk of developing simple visceral cysts, most commonly in the pancreas and kidneys, in addition to an increased risk of developing neoplasms, often with clear cell features, in a multitude of organ systems. The most common neoplasms are cerebellar and retinal hemangioblastomas, adrenal pheochromocytomas, clear cell renal cell carcinomas, pancreatic neuroendocrine tumors, pancreatic serous cystadenomas, and endolymphatic sac tumors. These lesions most commonly present during adulthood; however, screening and surveillance for the development of these lesions should begin in the pediatric years for patients with von Hippel-Lindau disease. In this review article, the genetics and most common neoplasms of von Hippel-Lindau disease are reviewed, with an eye towards implications for the pediatric patient.

Clear cell neuroendocrine tumor of pancreas: Endoscopic Ultrasound-guided fine needle aspiration diagnosis of an uncommon variant

The cytomorphologic features of clear cell neuroendocrine tumor of pancreas have been rarely reported in cytology literature. The cytomorphology of this rare variant mimics many primary and metastatic clear cell tumors of the pancreas. However, a precise cytological diagnosis can be rendered by awareness of this entity and judicious use of immunohistochemistry. We report one such case in a young woman diagnosed on endoscopic ultrasound fine needle aspiration. The tumor cells showed positive staining with synaptophysin, chromogranin, and also with inhibin.

Pancreatic neuroendocrine tumors in twelve baboons (Papio spp.)

BACKGROUND

Pancreatic neuroendocrine tumors (PNETs) are rare in nonhuman primates and in humans.

METHODS

Twenty-one PNETs from twelve female baboons (Papio spp.) from the Southwest National Primate Research Center were evaluated using histopathology and immunohistochemistry.

RESULTS

Histologically, all tumors were benign and had neuroendocrine packeting. Immunohistochemical staining for synaptophysin and chromogranin was positive in all tumors evaluated (17/17). Insulin was positive in 16 of 21 tumors. Somatostatin was positive in 9 of 20 tumors. Multifocal staining for glucagon and pancreatic polypeptide was evident in a minority of tumors (6/20 and 2/17, respectively). Gastrin and vasoactive intestinal peptide were negative in all tumors evaluated. Nine tumors expressed more than one hormone marker.

CONCLUSIONS

This is the first detailed pathologic study of pancreatic endocrine tumors in the baboon. The findings suggest that these tumors are generally benign and have similar morphologic and immunohistochemical features as those described in people, including the ability to express multiple hormones.

Histopathology of NET: Current concepts and new developments

The diagnosis of neuroendocrine tumors is based on their histopathologic appearance and immunohistochemical profile. With the WHO 2010 classification formal staging and grading was introduced for gastro-entero-pancreatic NET, however, the nomenclature for lung neuroendocrine tumors still relies on the carcinoid term. In this review we also focus on the situation of neuroendocrine carcinoma of unknown primary, tissue biomarkers and actual controversies in the histopathology of NEN.

ActivinB Is Induced in Insulinoma To Promote Tumor Plasticity through a β-Cell-Induced Dedifferentiation

Loss of pancreatic β-cell maturity occurs in diabetes and insulinomas. Although both physiological and pathological stresses are known to promote β-cell dedifferentiation, little is known about the molecules involved in this process. Here we demonstrate that activinB, a transforming growth factor β (TGF-β)-related ligand, is upregulated during tumorigenesis and drives the loss of insulin expression and β-cell maturity in a mouse insulinoma model. Our data further identify Pax4 as a previously unknown activinB target and potent contributor to the observed β-cell dedifferentiation. More importantly, using compound mutant mice, we found that deleting activinB expression abolishes tumor β-cell dedifferentiation and, surprisingly, increases survival without significantly affecting tumor growth. Hence, this work reveals an unexpected role for activinB in the loss of β-cell maturity, islet plasticity, and progression of insulinoma through its participation in β-cell dedifferentiation.

Pancreatic neuroendocrine tumors: A single-center 20-year experience with 100 patients

BACKGROUND/OBJECTIVES

Pancreatic neuroendocrine neoplasms (NENs) are rare tumors, exhibiting several morphological, functional, and behavioral characteristics. However, only few reports have evaluated large case series of pancreatic NEN.

METHODS

We conducted a retrospective review of 100 consecutive patients with pancreatic NEN diagnosed pathologically and treated at the National Cancer Center Hospital between 1991 and 2010.

RESULTS

The study included 48 males and 52 females (median age: 55 years). Fourteen patients had clinical symptoms caused by excess hormone secretion at diagnosis. Twelve patients were diagnosed with neuroendocrine tumor (NET) G1, 54 with NET G2, and 32 with neuroendocrine carcinoma (NEC) as per the 2010 World Health Organization classification. Distant metastases were observed in 25%, 43%, and 84% of the patients with NET G1, NET G2, and NEC, respectively. Serum levels of neuron-specific enolase and lactate dehydrogenase significantly increased in patients with NEC compared with those in patients with NET G1/G2. The 5-year survival rates of patients with NET G1, NET G2, and NEC were 91%, 69%, and 10%, respectively. Good performance status (PS), lower stage, and histopathological grade were identified as independent favorable prognostic factors.

CONCLUSIONS

Patients with NET G1/G2 treated with surgical resection had a good prognosis. Most patients with NEC exhibited distant metastases and had a poor prognosis. Staging classification and the WHO 2010 grading are important factors for selecting the appropriate treatment strategy and predicting prognosis for patients with pancreatic NEN.

Contrast enhancement pattern on multidetector CT predicts malignancy in pancreatic endocrine tumours

OBJECTIVES

Preoperative suspicion of malignancy in pancreatic neuroendocrine tumours (pNETs) is mostly based on tumour size. We retrospectively reviewed the contrast enhancement pattern (CEP) of a series of pNETs on multiphasic multidetector computed tomography (MDCT), to identify further imaging features predictive of lesion aggressiveness.

METHODS

Sixty pNETs, diagnosed in 52 patients, were classified based on CEP as: type A showing early contrast enhancement and rapid wash-out; type B presenting even (B1) or only (B2) late enhancement. All tumours were resected allowing pathologic correlations.

RESULTS

Nineteen pNETs showed type A CEP (5-20 mm), 29 type B1 CEP (5-80 mm) and 12 type B2 (15-100 mm). All tumours were classified as well differentiated tumours, 19 were benign (WDt-b), 15 with uncertain behaviour (WDt-u) and 26 carcinomas (WDC). None of A lesions were malignant (12 WDt-b; 7 WDt-u), all B2 lesions were WDC, 7 B1 lesions were WDt-b, 8 WDt-u and 14 WDC; 4/34 (12 %) lesions ≤2cm were WDC. CEP showed correlation with all histological prognostic indicators.

CONCLUSIONS

Correlating with the lesion grading and other histological prognostic predictors, CEP may preoperatively suggest the behaviour of pNETs, assisting decisions about treatment. Moreover CEP allows recognition of malignant small tumours, incorrectly classified on the basis of their dimension.

Pancreatic neuroendocrine tumors: accurate grading with Ki-67 index on fine-needle aspiration specimens using the WHO 2010/ENETS criteria

BACKGROUND

The natural history of pancreatic neuroendocrine tumors (panNETs) is extremely variable. One of the most controversial problems in diagnosis is the accurate prediction of the clinical behavior of these tumors. PanNETs that behave aggressively with a malignant course may have bland cytologic features, while some tumors with previously described "malignant" features may behave in a benign or indolent fashion. Various classification schemes have been proposed for grading panNETs. The European Neuroendocrine Tumor Society (ENETS) and 2010 World Health Organization (WHO) classification schemes include counting the mitotic index and/or the Ki-67 proliferation index for grading. The current study was undertaken to determine whether tumors sampled by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) can be accurately graded based on the Ki-67 index when compared to surgical samples.

METHODS

Corresponding EUS-FNA cytology and surgical tissue specimens were obtained for 22 tumors and stained for hematoxylin and eosin (H&E) and the Ki-67 proliferation marker (MIB-1 antibody). Samples were graded by scoring Ki-67 staining indices in accordance with the 2010 ENETS/WHO criteria. The grading scores assigned to the EUS-FNA cytology samples were compared with the scores assigned to the corresponding histological samples.

RESULTS

The majority (86%) of EUS-FNA cytology samples and corresponding surgical tissue specimens demonstrated concordant grading based on Ki-67 indices.

CONCLUSIONS

These results indicate that EUS-FNA cytology samples can be accurately graded based on the WHO Ki-67 labeling scheme. Thus, Ki-67 scoring in EUS-FNA cytology samples is an alternative approach for establishing the grade of panNETs. Accurate grading of panNETs is critical for predicting tumor biology, patient prognosis, and making informed decisions regarding patient management and treatment.

[Two cases reports of pancreatic endocrine microadenoma incidentally found]

A 59-year-old male, was admitted to our hospital for a tumor of the pancreatic tail. Serum CEA and CA 19-9 levels were normal. Splenopancreasectomy found a desmoid tumour. A 69-year-old male was referred to our institution for chronic anemia and inflammatory syndrome with splenomegaly. Splenectomy showed an important splenic congestion and siderosis. Both patients had a type 2 diabetes mellitus. Furthermore, histological examination revealed pancreatic endocrine microadenomas. The two patients' postoperative course was unremarkable. Eleven and 24 months respectively after the diagnosis, the patients are alive and well, with no tumor recurrence.

Precursor lesions of endocrine system neoplasms

The concept of precursor lesions of endocrine neoplasms is a new and interesting topic in endocrine pathology. A variety of clinicopathological conditions are associated with a sequence of cellular changes from hyperplasia to neoplasia; dysplasia is, in contrast, quite rare. The majority of precursor lesions is associated with familial genetic syndromes. These include C-cell hyperplasia in thyroid that is associated with familial medullary thyroid carcinoma, adrenal medullary hyperplasia as a precursor of phaeochromocytomas in MEN2 syndrome, rare pituitary adenohypophyseal cell hyperplasia in familial syndromes associated with pituitary adenomas, MEN1-related precursor gastric enterochromaffin-like cell (ECL) hyperplasia, and duodenal gastrin producing (G) and/or somatostatin producing (D) cell hyperplasia that give rise to type II gastric neuroendocrine tumours (NETs) and duodenal NETs, respectively, and MEN1- or VHL-related islet hyperplasia, islet dysplasia and ductulo-insular complexes that are associated with pancreatic NETs. Other hyperplasias are not thought to be associated with genetic predisposition. Some are attributed to inflammation; autoimmune chronic atrophic gastritis-related ECL hyperplasia can progress to type I gastric NETs, and EC (enterochromaffin) cell or L cell hyperplasia associated with inflammatory bowel diseases can progress to colorectal NETs. In the lung, diffuse idiopathic pulmonary neuroendocrine cell hyperplasia can give rise to peripherally-located low grade pulmonary NETs and tumourlets (neuroendocrine microtumours <5  mm). Rarely, secondary hyperplasias develop into autonomous neoplasms, as in tertiary hyperparathyroidism or pituitary thyrotroph adenomas in primary hypothyroidism. While some precursor lesions, such as thyroid C cell hyperplasia, represent frankly premalignant conditions, others may represent a sequence of proliferative changes from hyperplasia to benign neoplasia that may also progress to malignancy.

Animal models and cell lines of pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (PNETs), also known as islet cell tumors, are mostly indolent neoplasms that probably arise from a network of endocrine cells that includes islet cells and pluripotent precursors in the pancreatic ductal epithelium. The incidence and prevalence of PNETs continue to rise in recent years because of more sensitive detection. The molecular pathogenesis, early detection, molecular predictors of tumor behavior, and targeted drug therapy of PNETs are not well understood and require additional basic and translational research. The rarity and indolent nature of these tumors, difficulty of access to appropriate patient tissue samples, and varying histopathology and secreted hormones pose particular challenges to PNET researchers. Animal models and cell lines are indispensable tools for investigating the pathogenesis, pathophysiology, mechanisms for tumor invasion and metastasis, and therapeutics of PNETs. This review summarizes currently available animal models and cell lines of PNETs, which have provided valuable insights into the pathogenesis and natural history of human PNETs. In the future, animal models and cell lines of PNETs should also be used to study early tumor detection and molecular predictors of tumor behavior and to test the responses to, and mechanisms for, novel targeted drug therapies.

Pancreatic endocrine tumour with disseminated pulmonary thromboembolism in an owl monkey (Aotus nancymae)

Pulmonary thromboembolism associated with pancreatic endocrine neoplasia is extremely uncommon in man and animals. Post-mortem examination of an adult owl monkey (Aotus nancymae) revealed extensive pulmonary arterial thromboembolism and a well-demarcated mass attached to the pancreas. Microscopically, the mass consisted of areas of interstitial fibrosis with loss of acini and islets and replacement by nests and sheets of polygonal cells with amphophilic cytoplasm, an eccentric round nucleus with stippled chromatin and, in some cells, with a single prominent eccentric nucleolus. Clusters of these cells were noted within vessels and adjacent lymph nodes. The cells did not express S100 or insulin, but were labelled strongly with SP-1/chromogranin. Rare individual cells expressed glucagon and somatostatin. A few cells in pulmonary thrombi/emboli and the adjacent lymph node also expressed SP-1/chromogranin. Based on cell morphology, location and immunohistochemistry the tumour was classified as pancreatic endocrine (islet cell) carcinoma with metastasis to regional lymph nodes and lung.

Prognostic and predictive markers in medullary thyroid carcinoma

Unlike papillary thyroid carcinoma, medullary thyroid carcinoma is insensitive to adjuvant treatment with radioactive iodine. The clinical management of patients with advanced or metastatic disease remains challenging since no effective systemic adjuvant therapy is available. We aimed to identify markers of aggressive disease and novel drugable protein targets that would provide systemic adjuvant treatment for patients with advanced medullary thyroid carcinoma. We therefore examined morphologic features of aggressive behavior and the expression of 41 proteins involved in apoptosis, cell cycle, angiogenesis, inflammation, cell adhesion, tumor-specific markers, and WNT, SHH, and AKT pathways using tissue microarray from 23 patients with medullary thyroid carcinoma. Protein expression was determined using computerized image analysis software. Statistical analysis was carried out to correlate clinical data with the average score for each marker. Angioinvasion proved to be the most reliable predictor of disease recurrence and death. The rate of angioinvasion was 43 %. All angioinvasive medullary thyroid carcinomas had locoregional and/or distant metastasis; 60 % of angioinvasive medullary thyroid carcinomas developed distant metastasis. We identified expression of several potentially important protein targets such as COX-1/2, Bcl-2a, Gst-π, Gli-1, Gli-2, Gli-3, and Bmi-1 that may be therapeutically targeted in medullary thyroid carcinoma. More importantly, the immunohistochemical profile of SSTRs in medullary thyroid carcinoma may also have clinical relevance for the administration of peptide receptor radionuclide treatment. Successful outcome of clinical trials directed against these novel targets would provide much needed systemic adjuvant treatment for patients with advanced medullary thyroid carcinoma, and our data suggest the possibility of stratifying patients who are likely to require adjuvant therapy before their burden of disease precludes successful therapeutic effect.

Pasireotide (SOM230) is effective for the treatment of pancreatic neuroendocrine tumors (PNETs) in a multiple endocrine neoplasia type 1 (MEN1) conditional knockout mouse model

BACKGROUND

Pasireotide (SOM230), a long-acting somatostatin analogue (LAR), has improved agonist activity at somatostatin receptors. We tested the effect of SOM230 on insulin secretion, serum glucose concentrations, tumor growth, and survival using an MEN1 transgenic mouse model.

METHODS

Eight 12-month-old conditional Men1 knockout mice with insulinoma were assessed. The treatment (n = 4) and control groups (n = 4) received monthly subcutaneous injections of SOM230 or PBS. Serum insulin and glucose levels were determined by enzyme-linked immunosorbent assay and enzymatic colorimetric assay, respectively. Tumor activity, growth, and apoptosis were determined by microPET/CT scan and histologic analysis.

RESULTS

On day 7, there was a decrease in serum insulin levels from 1.06 ± 0.28 μg/L to 0.37 ± 0.17 μg/L (P = .0128) and a significant increase in serum glucose from 4.2 ± 0.45 mmol/L to 7.12 ± 1.06 mmol/L (P = .0075) in the treatment group but no change in the control group. Tumor size was less in the treatment group (2,098 ± 388 μm(2)) compared with the control group (7,067 ± 955 μm(2); P = .0024). Furthermore, apoptosis was increased in the treatment group (6.9 ± 1.23%) compared with the control group (0.29 ± 0.103%; P = .002).

CONCLUSION

SOM230 demonstrates antisecretory, antiproliferative, and proapoptotic activity in our MEN1 model of insulinoma. Further studies of the effects of SOM230 in PNET patients with MEN1 mutations are warranted.

Immuno-PET of tissue factor in pancreatic cancer

Upregulation of tissue factor (TF) expression leads to increased patient morbidity and mortality in many solid tumor types. The goal of this study was to develop a PET tracer for imaging of TF expression in pancreatic cancer.

METHODS

ALT-836, a chimeric antihuman TF monoclonal antibody, was conjugated to 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA) and labeled with (64)Cu. To compare the TF binding affinity of ALT-836 and NOTA-ALT-836, flow cytometry analysis was performed in 3 pancreatic cancer cell lines with different expression levels of TF (from low to high: PANC-1, ASPC-1, and BXPC-3). PET, biodistribution, blocking, and histology studies were performed on pancreatic tumor-bearing mice to evaluate the ability and specificity of (64)Cu-NOTA-ALT-836 to target TF in vivo.

RESULTS

There was no difference in TF binding affinity between ALT-836 and NOTA-ALT-836. (64)Cu-labeling was achieved with high yield and specific activity. Serial PET revealed that the uptake of (64)Cu-NOTA-ALT-836 in BXPC-3 tumors (high TF expression) was 5.7 ± 1.8, 10.4 ± 0.8, and 16.5 ± 2.6 percentage injected dose per gram at 4, 24, and 48 h after injection, respectively (n = 4), significantly higher than that in the PANC-1 and ASPC-1 tumors. Biodistribution data as measured by γ-counting were consistent with the PET findings. Blocking experiments and histology further confirmed the TF specificity of (64)Cu-NOTA-ALT-836.

CONCLUSION

Herein we report the first successful PET imaging of TF expression. Persistent and TF-specific uptake of (64)Cu-NOTA-ALT-836 was observed in pancreatic cancer models.