The Oberndorfer Centenary: 1907-2007

At the 100th anniversary of Oberndorfer’s extraordinary contribution, Professor Modlin invited three hundred leading international physicians and scientists to celebrate the “Karzinoide” discovery. These discussions, reflecting the current status of neuroendocrine tumor disease and cutting-edge developments in the understanding of amine and peptide secretion and suppression, as well as progress in the clinical management of the ubiquitous entity of carcinoid disease, are encapsulated in this book. This text edited with Professor Oberg presents a compendium of clinical and scientific information that summarizes the advances in neuroendocrine tumor biology, pathology and clinical practice in the last century. Both we and the distinguished physicians present acknowledge and celebrate the life and times of Oberndorfer, whose great accomplishment led to the elucidation of neuroendocrine tumor disease.

Kidd M, Gustafsson BI, Modlin IM. Genetics of Gastroenteropancreatic Tumors in “Handbook of Genetics.” Brenner S (eds). 2nd edition (2013)

Gastroenteropancreatic (GEP) and bronchopulmonary (BP) neuroendocrine neoplasms (NENs) represent the second most prevalent gastrointestinal malignancy, exhibit a poor prognosis but their etiopathogenesis is unknown. This chapter explores the mechanisms and genetic basis for the etiopathogenesis of this heterogeneous disease highlighting the significantly different genetic abnormalities that occur in each tumor sub-type.

Modlin IM, Gustafsson BI, Kidd M. Neuroendocrine Tumors of the GI Tract: An appraisal of the past and perspectives for the future in “The Oxford Textbook of Endocrinology and Diabetes” Meeran K, Bloom S (eds) Oxford University Press (2nd edition) (2010).

Increased knowledge about Neuroendocrine Tumor (NET) cellular biology and their genetic characteristics is the key to the evolution of therapy. The primary goal is the need to develop a surveillance test and identify sensitive blood-based markers that facilitate early diagnosis and can define prognosis. The obvious therapeutic goal is based upon the identification of molecular targets in a particular tumor and the development of effective tumor specific targeted therapeutic agents.

Modlin IM, Kidd M, Malfertheiner MV, Gustafsson BI. Gastric Neuroendocrine Neoplasia in “The Biology of Gastrointestinal Cancers” Wang TC, Fox JG, Giraud A (eds) Springer-Verlag, NY 2008; 185-216.

Gastric “carcinoids” or, as they are currently called “NENs” (neuroendocrine neoplasms) have, in recent times, become the subject of substantial clinical and investigative interest. This reflects global concerns regarding the consequences of prolonged hypochlorhydria, long-standing hypergastrinemia (increased use of acid suppressive pharmacotherapeutic agents) as well as the proposed putative relationship between gastric adenocarcinoma and gastric NENs.

A Nomogram to Assess Small-Intestinal Neuroendocrine Tumor ('Carcinoid')

Development of a "nomogram" that can be used to predict metastasis probability and assess outcome facilitates development of a management strategy.

Modlin IM, Gustafsson BI, Pavel M, Lawrence B, Svejda B, Kidd M

Abstract: Most information available to determine neuroendocrine tumor behavior reflects univariate assessment of factors or is anecdotal or experience based. There currently exists no objective multivariate analysis of indices that defines SI Neuroendocrine Tumor (NET) prognosis. A key unmet need is the lack of a rigorous mathematical-based tool – a nomogram – for the assessment of parameters that define progress, determine prognosis and can guide therapy. Since prediction of Neuroendocrine Tumor (NET) behavior is a critical criterion in determining clinical strategy, we constructed a Neuroendocrine Tumor (NET) nomogram (Modlin Score) for prognosis prediction, patient group comparisons and a guide for stratification of treatment and surveillance. External validation and amplification by identification of additional indices, e.g. molecular biomarkers, are necessary. The development of a mathematically validated nomogram provides a platform for objective assessment of SI Neuroendocrine Tumor (NET) disease, a finite basis for precise prognostication and a tool to guide management strategy.

The Clinical Relevance of Chromogranin A as a Biomarker for Gastroenteropancreatic Neuroendocrine Tumors

Numerous biomarkers have been proposed. Chromogranin A (CgA) is, by default, the most widely used in NET disease despite its unreliability.

Lawrence B, Gustafsson BI, Kidd M, Pavel M, Svejda B, Modlin IM

An accurate tumor marker is a critical tool in tumor management because it establishes an uncertain diagnosis, offers a basis for individual prognostication, signals response to therapy, and identifies relapse. In classical terms, a high-quality tumor marker should represent a biologic attribute unique to the tumor cell or its local environment. Although this has proved manageable in a homogenous tumor population, the goal has been difficult to attain in gastroenteropancreatic neuroendocrine tumors (GEP-NETs) because they comprise an extremely heterogeneous group of cancers. Thus, the conundrum of identifying a global marker for NETs has remained a considerable technical challenge.

Gastroenteropancreatic Neuroendocrine Tumours

The alterations in NET incidence from different sites demonstrate annualized percentage changes (APC) of 3-8%; these tumors are significantly increasing in incidence.

Modlin IM, Oberg K, Chung DC, Jensen RT, de Herder WW, Thakker RV, Caplin M, Delle Fave G, Kaltsas GA, Krenning EP, Moss SF, Nilsson O, Rindi G, Salazar R, Ruszniewski P, Sundin A.

Gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) are fairly rare neoplasms that present many clinical challenges. They secrete peptides and neuroamines that cause distinct clinical syndromes, including carcinoid syndrome. However, many are clinically silent until late presentation with mass eff ects. Investigation and management should be highly individualised for a patient, taking into consideration the likely natural history of the tumor and general health of the patient. Management strategies include surgery for cure (which is achieved rarely) or for cytoreduction, radiological intervention (by chemoembolisation and radiofrequency ablation), chemotherapy, and somatostatin analogues to control symptoms that result from release of peptides and neuroamines. New biological agents and somatostatin-tagged radionuclides are under investigation.

Gastrointestinal Neuroendocrine (Carcinoid) Tumours: Current Diagnosis and Management

A range of imaging modalities are available to identify NETs. The most sensitive are based on utilizing knowledge of tumor biology and cell function e.g., somatostatin receptor and Octreoscan.

Modlin IM, Moss SF, Oberg K, Padbury R, Hicks R, Gustafsson BI, Wright NA, Kidd M

The term carcinoid (carcinoma-like) was introduced byOberndorfer in 1907 to describe a tumor of the gastroin-testinal tract that was less aggressive than adenocarcinoma. The earliest clear description of carcinoid syndrome (flushing, diarrhoea, and bronchospasm) and carcinoid heart disease waspublished in the early 1950s. At the same time, the first systemicbiogenic amine producing these symptoms, 5-hydroxytryptamine,was identified, and the neuroendocrine origin of carcinoid tumors was established.

Systemic Therapeutic Options for Carcinoid

A variety of therapeutic strategies are associated with different outcomes. Surgery (when feasible and if the tumor is localized) appears to be the most effective therapy that translates into predictable and significant survival advantage.

Pavel M, Kidd M, Modlin IM.

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

Neuroendocrine Tumor Disease: an Evolving Landscape

A strategy analysis for NET disease identifies no certain targets and significant limitations of current experimental models. Both of these conclusions have resulted in the fact that there is no predictably effective agent.

Frilling A, Akerstrom A, Falconi M, Pavel M, J Ramos, Kidd M, Modlin IM.

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) represent a heterogenous group of tumors arising from a variety of neuroendocrine cell types. The incidence and prevalence of GEPNENs have markedly increased over the last three decades. Symptoms are often absent in early disease, or vague and nonspecific even in advanced disease. Delayed diagnosis is thus common. Chromogranin A is the most commonly used biomarker but has limitations as does the proliferative marker Ki-67%, which is often used for tumor grading and determination of therapy. The development of amultidimensional prognostic nomogrammay be valuable in predicting tumor behavior and guiding therapy but requires validation. Identification of NENs that express somatostatin receptors (SSTR) allows for SSTR scintigraphy and positron emission tomography imaging using novel radiolabeled compounds. Complete surgical resection of limited disease or endoscopic ablation of small lesions localized in stomach or rectum can provide cure; however, the majority of GEP-NENs are metastatic (most frequently the liver and/or mesenteric lymph nodes) at diagnosis. Selected patients with metastatic diseasemay benefit from advanced surgical techniques including hepatic resection or liver transplantation. Somatostatin analogs are effective for symptomatic treatment and exhibit some degree of antiproliferative activity in small intestinal NENs. There is a place for streptozotocin, temozolomide, and capecitabine in the management of pancreatic NENs, while new agents targeting either mTOR (everolimus) or angiogenic (sunitinib) pathways have shown efficacy in these lesions. Endocrine-Related Cancer (2012) 19 R163–R185

Review Article: Somatostatin Analogues in the Treatment of Gastroenteropancreatic Neuroendocrine (Carcinoid) Tumours

Drugs have been developed that variously target somatostatin receptors (sst1-5). Octreotide principally targets the type 2 receptor while pasireotide targets type 5 but also sst1, 2 and 3. The latter agent, however, has a serious adverse effect on glucose homeostasis producing a diabetes-like profile.

Modlin IM, Pavel M, Kidd M, Gustafsson BI.

Background: The discovery of somatostatin (SST) and the synthesis of a variety of analogues constituted a major therapeutic advance in the treatment of gastroenteropancreatic neuroendocrine (carcinoid) tumours (GEP-NETs). They currently provide the most efficient treatment to achieve symptomatic relief and have recently been demonstrated to inhibit tumour growth.

Recommendations for management of patients with neuroendocrine liver metastases

Potential strategies for the management of NET liver metastases management. In this era of personalized medicine, measurements of circulating signatures (A and B) can be used to assess efficacy and facilitate optimizing therapeutic strategy.

Frilling A, Modlin IM, Kidd M, Russell C, Breitenstein S, Salem R, Kwekkeboom D, Lau W-Y, Klersy C, Vilgrain V, Davidson B, Siegler M, Caplin M, Solcia E, Schilsky R, and the Working Group Neuroendocrine Liver Metastases.

Many management strategies exist for neuroendocrine liver metastases. These strategies range from surgery to ablation with various interventional radiology procedures, and include both regional and systemic therapy with diverse biological, cytotoxic, or targeted agents. A paucity of biological, molecular, and genomic information and an absence of data from rigorous trials limit the validity of many publications detailing management. This Review represents the views from an international conference, for which 15 expert working groups prepared evidence-based assessments addressing specific questions, and from which an independent jury derived fi nal recommendations. The aim of the conference was to review the existing approaches to neuroendocrine liver metastases, assess the evidence on which management decisions were based, develop internationally acceptable recommendations for clinical practice (when evidence was available), and make recommendations for clinical and research endeavours. This report represents the fi nal clinical statements and proposals for future research.

Predicting Neuroendocrine Tumor (Carcinoid) Neoplasia Using Gene Expression Profiling and Supervised Machine Learning

A Principal Component Analysis of gene expression from primary small intestinal NETs and their meetastases compared to normal neuroendocrine cells. This analysis demonstrates that normal, tumor and metastases profiles can be distinguished by the expressions of selected marker genes. This has enabled the development of molecular testing for tumor cells.

Drozdov I, Kidd M, Nadler B, Camp R, Mane M, Gustafsson BI, Hauso O, Modlin IM.

A more accurate taxonomy of small intestinal (SI) neuroendocrine tumors (NETs) is necessary to accurately predict tumor behavior, prognosis and define therapeutic strategy. We identified a panel of such markers implicated in tumorogenicity, metastasis, and hormone production and hypothesized that transcript levels of MAGE-D2, MTA1, NAP1L1, Ki-67, Survivin, FZD7, Kiss1, NRP2, and CgA could be used to define primary SI NETs and predict the development of metastases.

Gene Network Inference and Biochemical Assessment Delineates GPCR Pathways and CREB Targets in Small Intestinal Neuroendocrine Neoplasia

The cAMP-signal pathway network in small intestinal NETs (A) and identification of upstream (B) and downstream (C) gene targets. This analysis identifies which genes are activated when a neuroendocrine tumor cell responds to growth signals.

Drozdov I, Kidd M, Gustafsson BI, Mane S, Hauso O, Pfragner R, Modlin IM.

Small intestinal (SI) neuroendocrine tumors (NET) are increasing in incidence, however little is known about their biology. High throughput techniques such as inference of gene regulatory networks from microarray experiments can objectively define signaling machinery in this disease. Genome-wide co-expression analysis was used to infer gene relevance network in SI-NETs. The network was confirmed to be non-random, scale-free, and highly modular. Gene network inference and graph topology analysis in SI NETs suggests that SI NETs express neural GPCRs that activate different CRE targets associated with proliferation and secretion. In vitro studies, in a model Neuroendocrine Tumor (NET) cell system, confirmed that transcriptional effects are signaled through the cAMP/PKA/pCREB signaling pathway and that a SI Neuroendocrine Tumor (NET) cell line was most sensitive to a D2 and 5-HT2 receptor agonist BIM-53061.

KRJ-I and BON Cell Lines: Defining an Appropriate Enterochromaffin Cell Neuroendocrine Tumor Model

Transcriptome analysis of two common models of NETs - the human small intestinal cell line (KRJ-I-green) and a pancreatic cell line (BON-red). This investigation identified no genes to be commonly unregulated and that the two cell lines were completely different. The BON cell line is therefore not an appropriate experimental NET model.

Siddique Z-L, Drozdov I, Floch J, Gustafsson BI, Stunes K, Pfragner R, Kidd M, Modlin IM.

Neuroendocrine tumors (NETs) of the gastrointestinal (GI) system are increasing in incidence with minimal improvement in prognosis. Although the cell of origin has been identified as the enterochromaffin (EC) cell, its secretory and proliferative regulation has not been defined at a mechanistic level. To date, the BON cell line has been the most widely used in vitro EC cell model despite its pancreatic origin. Using whole-genome mathematical analysis as well as secretory and proliferative studies, we compared the BON cell line to the small intestine (SI) EC cell-derived Neuroendocrine Tumor (NET) cell line, KRJ-I, to assess individual cell line validity and applicability for the investigation of GI-Neuroendocrine Tumor (NET) disease. Our results demonstrate that KRJ-I and BON cell lines demonstrate substantial differences in gene level transcripts, inconsistent receptor profile expression, wide variability in NE marker transcript levels, and significantly differential proliferative and secretory responses. Given the EC cell origin of KRJ-I, these results provide evidence that the BON cell line does not represent an EC cell system and is not a valid study model of (carcinoid) EC cell- derived NET.

Comparison of PCR-based Detection of Chromogranin A mRNA with Traditional Histological Lymph Node Staging of Small Intestinal Neuroendocrine Neoplasia

Comparison of the sensitivity of standard histological approaches (histology - A, stained with chromogranin antibody - B) and PCR for the identification of metastases in lymph nodes. The PCR approach (C) is significantly more sensitive and identifies more positive lymph nodes.

Lawrence B, Kenney B, Svejda B, Schimmack S, Alaimo D, Barbieri A, Jedrych J, Kidd M, Modlin IM.

Background: Accurate neuroendocrine neoplasia (NEN) staging is vital for determining prognosis and therapeutic strategy. The great majority of NENs express chromogranin A (CgA) which can be detected at a protein or transcript level. The current standards for lymph node metastasis detection are histological examination after Hematoxylin and Eosin (H&E) and CgA immunohistochemical (IHC) staining. We hypothesized that detection of CgA mRNA transcripts would be a more sensitive method of detecting these metastases.

Principal Component Analysis, Hierarchical Clustering, and Decision Tree Assessment of Plasma mRNA and Hormone Levels as an Early Detection Strategy for Small Intestinal Neuroendocrine (Carcinoid) Tumors

Principal component analysis (A) and hierarchical clustering (B) of blood samples demonstrates that a combination of genes and hormones can be used to differentiate healthy controls from small intestinal NETs. These analyses indicate that the presence or absence of mRNA is adequate to establish distinct regulatory signatures for healthy controls and circulating tumor cells.

Modlin IM, Gustafsson BI, Drozdov I, Kidd M.

We sought to investigate whether detection of circulating messenger RNA (mRNA) alone or in combination with circulating NET-related hormones and growth factors could detect gastrointestinal Neuroendocrine Tumor (NET) disease. The small intestinal (SI) Neuroendocrine Tumor (NET) cell line KRJ-I was used to define the sensitivity of real-time polymerase chain reaction (PCR) for mRNA detection in blood. NSE, Tph-1, and VMAT2 transcripts were identified from one KRJ-I cell/ml blood. Tph-1 was a specific marker of SI-NETs (58%, p<0.03) whereas CgA transcripts did not differentiate tumors from controls. Patients with metastatic disease expressed more marker transcripts than localized tumors (75% versus 18%, p<0.02). Plasma 5-hydroxytryptamine (5-HT), chromogranin A (CgA), ghrelin, and connective tissue growth factor (CTGF) fragments were measured, combined with mRNA levels, and a predictive mathematical model for Neuroendocrine Tumor (NET) diagnosis developed using decision trees. The sensitivity and specificity to diagnose SI-NETs and gastric NETs were 81.2% and 100%, and 71.4% and 55.6%, respectively. We conclude that mRNA from one Neuroendocrine Tumor (NET) cell/ ml blood can be detected. Circulating plasma Tph-1 is a promising marker gene for SI-Neuroendocrine Tumor (NET) disease (specificity 100%) while an increased number of marker transcripts ([2) correlated with disease spread. Including NET-related circulating hormones and growth factors in the algorithm increased the sensitivity of detection of SI-NETs from 58 to 82%.

Serotonin and the 5-HT7 Receptor: The Link Between Hepatocytes, IGF-1 and Small Intestinal Neuroendocrine Tumors

The functional regulation of hepatocytes occurs via serotonin (5-HT) activation of 5-HT7 cell surface receptors. This receptor subtype regulates hepatocyte secretion of growth factors. Since serotonin is one of the principal products of intestinal metastases, it is axiomatic that it can regulate hepatocytes and thus self-modify the growth environment of liver metastases.

Svejda B, Kidd M, Timberlake A, Lawrence B, Harry K, Alaimo D, Kazberouk A, Schimmack S, Modlin IM.

Platelet-derived serotonin (5-HT) is involved in liver regeneration. The liver is also the metastatic site for malignant enterochromaffin (EC) cell “carcinoid” (neuroendocrine) neoplasms, the principal cellular source of 5-HT. We tested whether 5-HT produced by metastatic EC cells played a role in the hepatic tumor-microenvironment through 5-HT7 receptor-mediated activation of hepatocyte IGF-1 synthesis and secretion. Our results demonstrated evidence for a functional 5-HT7 receptor in the liver and identified that IGF-1 and 5-HT were elevated in peri-tumoral hepatic tissue in nude mice, while 5-HT7 was increased fourfold compared to sham-operated animals. We conclude that hepatocytes express a cAMP-coupled 5-HT7 receptor, which, at elevated 5-HT concentrations that occur in liver metastases, signals via CREB ⁄ AKT and is linked to IGF-1 synthesis and secretion. Because IGF-1 regulates NEN proliferation, identification of a role for 5-HT7 in the hepatic metastatic tumor microenvironment suggests the potential for novel therapeutic strategies for amine-producing mid-gut tumors.

Limitations in Small Intestinal Neuroendocrine Tumor Therapy by mTor Kinase Inhibition Reflect Growth Factor–Mediated PI3K Feedback Loop Activation via ERK1/2 and AKT

Schematic of the mTOR pathway in NETs (A). This demonstrates (B) inhibition of the pathway that activates an escape signal (activation of the ERK pathway that results in compensatory growth). These pathways are highly activated in NETs (C, D) providing a basis for understanding the substantial limitations of the mTOR class of drugs.

Svejda B, Kidd M, Kazberouk A, Lawrence B, Pfragner R, Modlin IM.

BACKGROUND: Treatment of small intestinal neuroendocrine tumors (SINETs) with mammalian target of rapamycin (mTOR) inhibitors alone or with somatostatin analogs has been proposed as effective therapy, because both agents have been reported to exhibit antiproliferative activity. Because adenocarcinomas escape mTOR inhibition, we examined whether the escape phenomenon occurred in SINETs and whether usage of somatostatin analogs with mTOR inhibitors surmounted loss of inhibition.

2018 NETest Slide Set