Ramucirumab in combination with dacarbazine in patients with progressive well-differentiated metastatic pancreatic neuroendocrine tumors (RamuNET): study protocol for a multicenter single-arm trial

BACKGROUND

Cytotoxic chemotherapy combinations and targeted agents represent established treatment concepts in advanced pancreatic neuroendocrine tumors (PNETs). However, response rates, side effects and outcome data strongly vary among these therapeutic approaches. Head-to-head comparisons between chemo- and molecular therapies are missing and secondary resistances frequently occur. The RamuNET trial aims to identify the effectiveness of dual treatment with DTIC and ramucirumab in progressive advanced PNET patients.

METHODS

The RamuNET study is an investigator-initiated multicenter prospective single-arm trial to evaluate the efficacy of ramucirumab in combination with dacarbazine (DTIC) over a period of at least 6 months. Patients with progressive well-differentiated and metastatic pancreatic neuroendocrine tumors are eligible. The study aims to include 45 patients over a period of 24 months with a minimum follow-up of 24 months. The primary endpoint is disease control after 6 months. Secondary endpoints include progression-free survival, biochemical response, overall survival, quality of life and toxicity. Based on the hypothesis that 80% of the patients can achieve a disease control after 6 months, the sample size calculation follows an exact binomial single-stage design. H0: p < =p0 = 60% versus H1: p > =p1 = 80%, alpha = 0.05, beta = 0.1.

DISCUSSION

This study investigates a new therapeutic approach using the combination of cytotoxic and targeted antiangiogenic therapy in advanced PNET. If positive, this trial will be the basis for a randomized two-arm study to investigate the combination of ramucirumab and DTIC against other established therapies in PNET.

TRIAL REGISTRATION

EudraCT: 2017-001207-68 . Date of registration: 2018.01.03.

The distinctive characteristics of the micro-vasculature and immune cell infiltration in cystic pancreatic neuroendocrine tumors

PURPOSE

Hypervascularity is a main characteristic of pancreatic neuroendocrine tumors (PanNETs), and cystic PanNETs (CPanNETs) are unique type of PanNETs in which the microenvironment remains unknown. We aim to compare the micro-vasculature features and immune cell infiltration between CPanNETs and solid PanNETs (SPanNETs).

METHODS

Data of 301 SPanNET and 36 CPanNET patients from a high-volume institution were evaluated. CD4, CD8, CD11c, CD15, CD20, CD68, CD34 and α-SMA expression levels were assessed by immunohistochemistry and immunofluorescent double staining. The microvessel density (MVD) and microvessel integrity (MVI) were examined.

RESULTS

MVD and MVI expression levels in CPanNETs were significantly higher than those in SPanNETs (p = 0.025 and 0.0092, respectively). CPanNETs had higher proportions of T1 (p = 0.023) and G1 (p = 0.052) than SPanNETs. In SPanNETs, higher MVD occurred in stages T1, N0 and G1 than in the T2/T3, N1 and G2 subgroups. In CPanNETs, CD34-MVD was uncorrelated with the T stage or grade. Higher CD34-MVD, but not MVI, was associated with better DFS (HR 0.3209, 95% CI 0.1259-0.8176, p = 0.004). There were significantly more peritumoral infiltrating immune cells than their intratumoral counterparts (p < 0.001 for each) in CPanNETs and SPanNETs. The mean number of peritumoral CD68 + TAM in CPanNETs was significantly lower than that in SPanNETs (p = 0.008). The counts of other peritumoral immune cells did not significantly differ between CPanNETs and SPanNETs.

CONCLUSIONS

CPanNETs had a microenvironment distinct from that of SPanNETs, including higher CD34-MVD, higher MVI and lower TAM. This specific microenvironment structure may partially help predicting the prognosis of patients with PanNET.

The impact of SST2 trafficking and signaling in the treatment of pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (Pan-NETs), are heterogeneous neoplasms, whose incidence and prevalence are increasing worldwide. Pan-NETs are characterized by the expression of somatostatin receptors (SSTs). In particular, SST2 is the most widely distributed SST in NETs, thus representing the main molecular target for somatostatin analogs (SSAs). SSAs are currently approved for the treatment of well-differentiated NETs, and radionuclide-labeled SSAs are used for diagnostic and treatment purposes. SSAs, by binding to SSTs, have been shown to inhibit hormone secretion and thus provide control of hypersecretion symptoms, when present, and inhibit tumor proliferation. After SSA binding to SST2, the fate of the receptor is determined by trafficking mechanisms, crucial for the response to endogenous or pharmacological ligands. Although SST2 acts mostly through G protein-dependent mechanism, receptor-ligand complex endocytosis and receptor trafficking further regulate its function. SST2 mediates the decrease of hormone secretion via a G protein-dependent mechanism, culminating with the inhibition of adenylyl cyclase and calcium channels; it also inhibits cell proliferation and increases apoptosis through the modulation of protein tyrosine phosphatases. Moreover, SST2 inhibits angiogenesis and cell migration. In this respect, the cross-talk between SST2 and its interacting proteins, including Filamin A (FLNA) and aryl hydrocarbon receptor-interacting protein (AIP), plays a crucial role for SST2 signaling and responsiveness to SSAs. This review will focus on recent studies from our and other groups that have investigated the trafficking and signaling of SST2 in Pan-NETs, in order to provide insights into the mechanisms underlying tumor responsiveness to pharmacological treatments.

The Tumor Microenvironment in Neuroendocrine Tumors: Biology and Therapeutic Implications

Neuroendocrine tumors (NETs) include a heterogeneous group of malignancies arising in the diffuse neuroendocrine system and characterized by indolent growth. Complex interactions take place among the cellular components of the microenvironment of these tumors, and the recognition of the molecular mediators of their interplay and cross talk is crucial to discover novel therapeutic targets. NET cells overexpress a plethora of proangiogenic molecules including vascular endothelial growth factor, platelet-derived growth factor, fibroblast growth factor, semaphorins, and angiopoietins that promote both recruitment and proliferation of endothelial cell precursors, thus resulting among the most vascularized cancers with a microvessel density 10-fold higher than epithelial tumors. Also, NETs operate multifaceted interactions with stromal cells, both at local and distant sites, and whether their paracrine secretion of serotonin, connective tissue growth factor, and transforming growth factor β primarily drives the fibroblast activation to enhance the tumor proliferation, on the other side NET-derived profibrotic factors accelerate the extracellular matrix remodeling and contribute to heart valves and/or mesenteric fibrosis development, namely, major complications of functioning NETs. However, at present, little is known on the immune landscape of NETs, but accumulating evidence shows that tumor-infiltrating neutrophils, mast cells, and/or macrophages concur to promote the neoangiogenic switch of these tumors by either direct or indirect mechanisms. On the other hand, immune checkpoint molecules are heterogeneously expressed in NETs' surrounding cells, and it is unclear whether or not tumor-infiltrating lymphocytes are antitumor armed within the microenvironment, given their low mutational load. Here, we review the current knowledge on both gastroenteropancreatic and pulmonary NETs' microenvironment as well as both established and innovative treatments aimed at targeting the tumor-host interplay.

Perfusion computed tomography as functional biomarker in randomized run-in study of bevacizumab and everolimus in well-differentiated neuroendocrine tumors

OBJECTIVES

This study aimed to assess the antitumor activity of everolimus and bevacizumab among patients with advanced neuroendocrine tumors and to assess perfusion computed tomography (CT) as a potential functional biomarker.

METHODS

Patients with low- to intermediate-grade neuroendocrine tumors received one 3-week cycle of 15 mg/kg of bevacizumab on day 1 or 10 mg of everolimus daily. Subsequent cycles consisted of the combination of both drugs. Perfusion CTs were performed at baseline and at the end of cycles 1 and 3.

RESULTS

Therapy decreased blood flow (BF) proportional to baseline measurements. Bevacizumab was associated with a 44% decrease in BF (P < 0.0001). After the addition of everolimus, a further 29% decrease (P = 0.02) in BF was observed. Everolimus alone was associated with 13% increase in mean transit time (P = 0.02). Clinical activity was demonstrated, with a confirmed response rate of 21% and a median progression-free survival of 14.6 (95% confidence interval, 13.0-16.1) months. Pretreatment tumor permeability surface (P = 0.009), posttreatment mean transit time (P = 0.003), percent reduction in BF (P = 0.03), and percent reduction in blood volume (P = 0.002) were associated with best percent reduction in tumor diameters.

CONCLUSIONS

Bevacizumab and everolimus demonstrated antitumor activity. Perfusion CT is a promising tool for the development of antiangiogenic strategies and for the selection of patients who are likely to benefit from therapy.

A nonfunctional neuroendocrine tumor of the pancreas - a case report

Pancreatic neuroendocrine tumors (pNETs) represent about 1-5% of the pancreatic tumors, having an annual incidence of about 1/100 000, with difficult positive and differential diagnostic, especially in nonfunctioning tumors. We present a case of large dimensions (10/8 cm) pancreatic tail NET developed in a 65-year-old woman, incidentally discovered while she was examined for a strangled inguinal hernia. The patient had no specific tumor signs and the imagistic examination did not reveal any metastases. The histopathological and especially the immunohistochemical examinations were decisive for the diagnosis, treatment and prognostic establishment. The tumor showed intense positivity for chromogranin, synaptophysin, CD56, CD117, CK19, MNF-116 and negative for CK5/6 and CK7. The proliferative index established through the Ki-67 assessment was around 3%, while p53 was positive in 25-30% of tumor cells nuclei.

"Leiomyomatoid angiomatous neuroendocrine tumor" (LANT) of the pituitary reflects idiosyncratic angiogenesis in adenomas of the gonadotroph cell lineage

Based on a single-case observation, the descriptive label "leiomyomatoid angiomatous neuroendocrine tumor" (LANT) has been tentatively applied to what was perceived as a possible novel type of dual-lineage pituitary neoplasm with biphasic architecture. We report on two additional examples of an analogous phenomenon encountered in male patients, aged 59 years (Case 1) and 91 years (Case 2). Both tumors were intra- and suprasellar masses, measuring 5.6 cm × 4.4 cm × 3.4 cm, and 2.7 cm × 2 cm × 1.7 cm, respectively. Histologically, Case 1 was an FSH-cell adenoma interwoven by vascularized connective tissue septa that tended to exhibit incremental stages of adventitial overgrowth. The epithelial component of Case 2 corresponded to an LH-cell adenoma, and lay partitioned by a maze of paucicellular to hyalinized vascular axes. Irrespective of architectural variations, perivascular spindle cells exhibited immunopositivity for vimentin, muscular actin, and smooth muscle actin. Conversely, negative results were obtained for CD34, EMA, S100 protein, GFAP, and TTF-1. Ultrastructural study failed to reveal metaplastic cell forms involving transitional features between adenohypophyseal-epithelial and mesenchymal-contractile phenotype. We propose that LANT be regarded as a peculiar reflection of maladaptive angiogenesis in some pituitary adenomas, rather than a genuine hybrid neoplasm. While no mechanistic clue is forthcoming to account for this distinctive pattern, hemodynamic strain through direct arterial - rather than portal - supply of the adenoma's capillary bed may be one such explanatory factor. The apparent predilection of the LANT pattern for macroadenomas of the gonadotroph cell lineage remains unexplained.

Expression of gremlin 1 correlates with increased angiogenesis and progression-free survival in patients with pancreatic neuroendocrine tumors

BACKGROUND

Gremlin 1 (GREM1) is a bone morphogenetic protein antagonist and a novel proangiogenic factor. Our aim was to evaluate the prognostic value of GREM1 expression and GREM1-related factors in tumor-associated angiogenesis in pancreatic neuroendocrine tumors (NETs).

METHODS

The immunohistochemical expression of GREM1 and microvessel density (MVD) were examined in 35 patients with pancreatic NETs and then compared with other clinicopathologic characteristics, including the World Health Organization classification.

RESULTS

The presence of expression of GREM1 (p = 0.016) and high MVD (p = 0.020) were significant and favorable prognostic factors. Moreover, GREM1 expression was significantly associated with high MVD (p = 0.011). MVD was significantly higher in well-differentiated NETs than in well-differentiated or poorly differentiated neuroendocrine carcinomas (p < 0.001).

CONCLUSIONS

GREM1 expression was correlated with tumor-associated angiogenesis and was found to be a novel prognostic marker in pancreatic NETS. Our data support a tumor suppressor role of GREM1 in pancreatic NETs.

Novel therapeutic agents for the treatment of gastroenteropancreatic neuroendocrine tumors

Neuroendocrine tumors (NET) are frequently diagnosed late and not amenable to curative surgery due to metastatic disease to the liver and lymph nodes. The disease is complex and heterogeneous given the various functionalities, distinct tumor growth patterns, and tumor spread upon diagnosis. Established therapies include somatostatin analogues, alpha-interferon, systemic chemotherapy, and loco-regional therapies of the liver. The availability of novel agents and expression of targets, such as growth factor receptors, different subtypes of somatostatin receptors, and the mammalian target of rapamycin (mTOR) have led to the exploration of different classes of drugs and offer new treatment opportunities in neuroendocrine tumors. This review provides an overview on novel drugs, focus on the impact of recently approved drugs on the management of NET disease, and outline future perspectives.

Use of a mouse model of pancreatic neuroendocrine tumors to find pericyte biomarkers of resistance to anti-angiogenic therapy

The successful introduction of rationally targeted agents into standard cancer care is a testimony of the vast knowledge base in tumor biology. However, in order to provide individually tailored therapy to patients and to identify small subsets of patients with a high likelihood to benefit from treatment, the identification of biomarkers for response or resistance to a particular therapeutic regimen is imperative. Herein, by the use of a genetically engineered mouse model of pancreatic neuroendocrine tumors, we have assessed the utility of pericyte characteristics in terms of differential marker expression to serve as surrogate markers for response or evasive resistance to anti-angiogenic therapy. We found that tumors refractory to therapy following long-term treatment with a vascular endothelial growth factor receptor-2 blocking antibody contained blood vessels with a prolific investment of pericytes expressing α-smooth muscle actin. Further analysis by simultaneous immunostaining for different pericyte markers led to the conclusion that the increased abundance of this particular subtype of blood vessels most likely occurred by co-option of vessels from the surrounding exocrine pancreas. Our findings may form the basis for retrospective analysis of pancreatic neuroendocrine tumors from patients having undergone treatment with anti-angiogenic agents in order to validate the occurrence of pericytes expressing α-smooth muscle actin as a biomarker for tumors refractory to therapy.

Pancreatic neuroendocrine tumors in glucagon receptor-deficient mice

Inhibition of glucagon signaling causes hyperglucagonemia and pancreatic α cell hyperplasia in mice. We have recently demonstrated that a patient with an inactivating glucagon receptor mutation (P86S) also exhibits hyperglucagonemia and pancreatic α cell hyperplasia but further develops pancreatic neuroendocrine tumors (PNETs). To test the hypothesis that defective glucagon signaling causes PNETs, we studied the pancreata of mice deficient in glucagon receptor (Gcgr^−/−) from 2 to 12 months, using WT and heterozygous mice as controls. At 2–3 months, Gcgr^−/− mice exhibited normal islet morphology but the islets were mostly composed of α cells. At 5–7 months, dysplastic islets were evident in Gcgr^−/− mice but absent in WT or heterozygous controls. At 10–12 months, gross PNETs (≥1 mm) were detected in most Gcgr^−/− pancreata and micro-PNETs (<1 mm) were found in all (n = 14), whereas the islet morphology remained normal and no PNETs were found in any WT (n = 10) or heterozygous (n = 25) pancreata. Most PNETs in Gcgr^−/− mice were glucagonomas, but some were non-functioning. No tumors predominantly expressed insulin, pancreatic polypeptide, or somatostatin, although some harbored focal aggregates of tumor cells expressing one of those hormones. The PNETs in Gcgr^−/− mice were well differentiated and occasionally metastasized to the liver. Menin expression was aberrant in most dysplatic islets and PNETs. Vascular endothelial growth factor (VEGF) was overexpressed in PNET cells and its receptor Flk-1 was found in the abundant blood vessels or blood islands inside the tumors. We conclude that defective glucagon signaling causes PNETs in the Gcgr^−/− mice, which may be used as a model of human PNETs. Our results further suggest that completely inhibiting glucagon signaling may not be a safe approach to treat diabetes.

The role of angiogenesis in neuroendocrine tumors

The first studies to assess in vitro angiogenesis in neuroendocrine tumors used animal-based assays to study the antiangiogenic properties of somatostatin analogs. Current technologies enable investigators to directly appraise the in vitro angiogenic response of an individual's neuroendocrine tumor with and without potential antiangiogenic reagents. This article describes the evolution of methods to assess in vitro angiogenesis in neuroendocrine tumors and describes some of the clinical data.

Quantitative gene-expression of the tumor angiogenesis markers vascular endothelial growth factor, integrin alphaV and integrin beta3 in human neuroendocrine tumors

Anti-angiogenesis treatment is a promising new therapy for cancer that recently has also been suggested for patients with neuroendocrine tumors. The aim of the present study was therefore to investigate the level of tumor angiogenesis, and thereby the molecular basis for anti-angiogenesis treatment, in neuroendocrine tumors. We used quantitative real-time PCR for measuring mRNA gene-expression of vascular endothelial growth factor (VEGF), integrin alphaV, and integrin beta3, and CD34 for a group of patients with neuroendocrine tumors (n=13). Tissue from patients with colorectal cancer liver metastases (n=14) and normal liver tissues (n=16) was used as control. We found a lower mRNA level of VEGF in neuroendocrine tumors compared to both colorectal liver metastases (p<0.001) and normal liver tissue (p<0.01). For integrin beta3 there was also a borderline significant lower level of mRNA in neuroendocrine tumors compared to both colorectal liver metastases (p=0.10) and normal liver tissue (p=0.06). In neuroendocrine tumors, gene-expression was highly variable of VEGF (530-fold), integrin alphaV (23-fold) and integrin beta3 (106-fold). Quantitative gene-expression levels of the key angiogenesis molecules VEGF and integrin beta3 were lower in neuroendocrine tumors than in colorectal liver metastases and were highly variable. Therefore, individual selection of patients may be necessary if anti-angiogenesis treatment is to be successful in patients with neuroendocrine tumors.

PET/CT with Gluc-Lys-([(18)F]FP)-TOCA: correlation between uptake, size and arterial perfusion in somatostatin receptor positive lesions

PURPOSE

Somatostatin receptor (sstr) positive tumours vary widely in uptake of radiolabelled somatostatin (sst) analogues. This study determinates variability in lesion uptake of the glycosylated sst analogon N(alpha)-(1-deoxy-D-fructosyl)-N(epsilon)-(2-[(18)F]fluoropropionyl)-Lys(0)-Tyr(3)-octreotate (Gluc-Lys([(18)F]FP)-TOCA) and correlates it with lesion size and arterial perfusion as measured on computed tomography (CT).

METHODS

Ten patients with metastasized neuroendocrine carcinomas were investigated with positron emission tomography PET/CT (Biograph 16, Siemens, Germany). Lesion standardized uptake values (SUVs) were determined at approximately 50 min post tracer injection according to a 60% isocontour volume of interest around each lesion. Lesion size and enhancement in the arterial phase (hounsfield units, HUs) were derived from CT.

RESULTS

114 lesions in the upper abdomen had a correlate on both, PET and CT. Variability in lesion SUVs was high (SUV(mean) 22 +/- 13). Intraindividually, there was a sigmoid positive correlation between lesion SUV and lesion diameter indicating partial volume effects. Residual variability in lesions > or =3 cm (> or =2.5 cm) ranged down to about half (third) of the maximum lesion uptake and remained unexplained by partial volume effects. No correlation with measured HU in the arterial phase was found, neither intraindividually nor interindividually.

CONCLUSION

Partial volume effects were a major source of intraindividual variability in tumour tracer uptake. Lesions below 2.5 to 3 cm should thus be used with caution when performing dose calculations. In larger lesions residual variability in uptake must be considered; it may be due to variable sstr2 expression on the tumours' cell surfaces.

New drug development in digestive neuroendocrine tumors

The traditional cytotoxic agents are of limited efficacy in the treatment of neuroendocrine tumors of the gastrointestinal tract (NETs). Recent investigations have brought up a number of biological features in this family of neoplasms that could represent targets for anticancer treatment. NETs seem to have an extraordinary tumor vascularization with high expression of proangiogenic molecules such as the vascular endothelial growth factor along with overexpression of certain tyrosine kinase receptors such as the epidermal growth factor receptor (EGFR), the insulin growth factor receptor (IGFR) and their downstream signaling pathway components (PI3K-AKT-mTOR). The rationale of an antiangiogenic approach in the treatment of NETs and the use of other pharmacological strategies such as EGFR, IGFR and mammalian target of rapamycin inhibitors are discussed. Additionally, the emerging results of recent clinical trials with these targeted drugs are presented.

Analysis of neuroendocrine tumour metastases in the liver using contrast enhanced ultrasonography

BACKGROUND

Imaging of liver tumours might be improved by contrast-enhanced ultrasonography, which allows much better demonstration of the microvascular system. The aim of this study was to assess the sonographic morphology and vascularity of neuroendocrine liver metastases.

METHODS

Forty-eight patients with histologically proven neuroendocrine tumours (NET) and suspected liver metastases--as well as 50 consecutive patients with liver metastases of other origins--were included in a prospective study to evaluate tumour characteristics using B-mode, colour Doppler (CDI) and contrast-enhanced ultrasound (CEUS).

RESULTS

In 4/48 patients with NET, liver biopsy revealed hemangiomas. The typical B-mode appearance was that of both echo-rich and echo-poor combined, also inhomogeneous depending on the size, and often centrally cystic. With CDI, neuroendocrine metastases appeared hypervascular (66%) or isovascular (34%). Metastases of another origin were hypovascular in 82%. With CEUS, neuroendocrine metastases showed increased arterial enhancement in 38 patients and hypoechoic appearance in the portalvenous phase in 39 patients. In liver metastases of another origin, the sensitivity for malignancy due to a hypoechoic appearance during the portalvenous phase was 100%. In liver metastases of NET origin the sensitivity for malignancy was 39/48 (82%).

CONCLUSIONS

Neuroendocrine tumour metastases might show characteristics which are similar to hemangiomas. In patients with liver cirrhosis and severe fatty liver disease the identification of NET with CEUS as a malignant lesion is more difficult. The sensitivity of CEUS in identifying malignancy based on the lack of portalvenous enhancement is higher for metastases of other origin.

Microvascular density does not correlate with histopathology and outcome in neuroendocrine tumors of the pancreas

Microvascular density (MVD), a marker for tumor angiogenesis, has been demonstrated to have prognostic significance in various malignancies. Previous studies have demonstrated that MVD is an independent prognostic factor in pancreatic adenocarcinoma and that longer survival is associated with hypovascular tumors. The prognostic importance of MVD in pancreatic neuroendocrine tumor (NET) has not been documented. We evaluated MVD in pancreatic NET and correlated it with clinicopathologic features and patient outcome to determine whether MVD is a useful prognostic indicator for these patients. Twenty-five pancreatic NETs from our archival files resected between 1981 and 2000 were identified. The mean MVD was determined for each tumor from the 3 most vascularized 200 x fields. Clinical follow-up ranged from 1 to 19 years, with a mean of 4.9 years. At last follow-up, 6 patients were dead of disease, 10 patients were alive without disease, 4 patients were alive with disease, and 5 patients were alive with disease status unknown. Mean MVD ranged from 43 to 527 microvessels per 200 x field. MVD did not correlate with tumor size, the examined histologic parameters, or patient outcome. MVD in pancreatic NET does not correlate with the clinicohistologic features evaluated in this study or with the patient outcome and is not a useful prognostic indicator in these patients. These results suggest that factors other than the simple number of microvessels are important in determining pancreatic NET behavior. However, most tumors were highly vascular, and additional studies may be helpful to clarify further the role of vascularity and assess the utility of antiangiogenic agents in the treatment of pancreatic NET.

Angiogenesis in endocrine tumors

Angiogenesis is the process of new blood vessel development from preexisting vasculature. Although vascular endothelium is usually quiescent in the adult, active angiogenesis has been shown to be an important process for new vessel formation, tumor growth, progression, and spread. The angiogenic phenotype depends on the balance of proangiogenic growth factors such as vascular endothelial growth factor (VEGF) and inhibitors, as well as interactions with the extracellular matrix, allowing for endothelial migration. Endocrine glands are typically vascular organs, and their blood supply is essential for normal function and tight control of hormone feedback loops. In addition to metabolic factors such as hypoxia, the process of angiogenesis is also regulated by hormonal changes such as increased estrogen, IGF-I, and TSH levels. By measuring microvascular density, differences in angiogenesis have been related to differences in tumor behavior, and similar techniques have been applied to both benign and malignant endocrine tumors with the aim of identification of tumors that subsequently behave in an aggressive fashion. In contrast to other tumor types, pituitary tumors are less vascular than normal pituitary tissue, although the mechanism for this observation is not known. A relationship between angiogenesis and tumor size, tumor invasiveness, and aggressiveness has been shown in some pituitary tumor types, but not in others. There are few reports on the role of microvascular density or angiogenic factors in adrenal tumors. The mechanism of the vascular tumors, which include adrenomedullary tumors, found in patients with Von Hippel Lindau disease has been well characterized, and clinical trials of antiangiogenic therapy are currently being performed in patients with Von Hippel Lindau disease. Thyroid tumors are more vascular than normal thyroid tissue, and there is a clear correlation between increased VEGF expression and more aggressive thyroid tumor behavior and metastasis. Although parathyroid tissue induces angiogenesis when autotransplanted and PTH regulates both VEGF and MMP expression, there are few studies of angiogenesis and angiogenic factors in parathyroid tumors. An understanding of the balance of angiogenesis in these vascular tumors and mechanisms of vascular control may assist in therapeutic decisions and allow appropriately targeted treatment.

Effects of interferon alpha on vascular endothelial growth factor gene transcription and tumor angiogenesis

BACKGROUND

Interferon alpha (IFN-alpha) has antiangiogenic activity, although the underlying mechanism of action is unclear. Because human neuroendocrine (NE) tumors are highly vascularized and sensitive to IFN-alpha, we investigated whether the therapeutic effects of IFN-alpha result from an inhibition of angiogenesis mediated by a decrease in vascular endothelial growth factor (VEGF) gene expression.

METHODS

VEGF gene and protein expression was analyzed in NE tumors by immunohistochemistry and in NE tumor cell lines by quantitative competitive reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). VEGF promoter-reporter gene constructs containing various deletions or mutations and gel shift assays were used to identify minimal promoter requirements and potential transcription factors. A xenograft nude mouse model (five mice per group) was used to determine the effect of IFN-alpha on tumor growth (NE Bon cells and pancreatic Capan-1 cells) and microvessel density. Liver metastases from eight patients with NE tumors were analyzed for microvessel density, VEGF mRNA content, and VEGF plasma levels before and after initiation of IFN-alpha therapy.

RESULTS

NE tumors and cell lines expressed VEGF mRNA and secreted VEGF protein. In vitro, IFN-alpha decreased transcription of VEGF gene expression through an Sp1- and/or Sp3-dependent inhibition of VEGF promoter activity. Compared with vehicle treatment in mice, IFN-alpha inhibited tumor growth by 36% and reduced microvessel density from 56 (95% confidence interval [CI] = 49 to 69) to 37 per x400 Field (95% CI = 32 to 41, P =.015). Patients with NE tumors had lower VEGF plasma levels and reduced VEGF mRNA levels and microvessel density in liver metastasis biopsy material after IFN-alpha treatment.

CONCLUSION

IFN-alpha confers its antitumor activity, at least in part, by its antiangiogenic activity, which results from Sp1- and/or Sp3-mediated inhibition of VEGF gene transcription.

Multidetector-row CT and volumetric imaging of pancreatic neoplasms

Multidetector-row CT provides excellent visualization of the pancreas and peripancreatic structures, yielding information that is crucial for detecting pancreatic neoplasms and accurately determining their staging. This new technology enables the acquisition of large volumetric data sets to create high-quality curved planar reformations that clearly depict the common bile duct, the pancreatic duct, and the peripancreatic vasculature. Additionally, curved planar reformations highlight critical anatomic and pathologic relationships which are useful for surgical planning in patients with resectable disease.

[Differential diagnosis of frequent pancreatic tumours with echo-enhanced power-Doppler sonography - presentation of case reports]

The echo-enhanced Power-Doppler sonography is useful for the differential diagnosis of pancreatic tumours. Tumour criteria for the differentiation of pancreatic tumours with this procedure are explained using selected cases in the present publication. Ductal carcinomas are often hypovascularised compared with the surrounding tissue. On the other hand, neuroendocrine tumours are hypervascularised lesions. Tumours associated with pancreatitis have a different vascularisation pattern depending on inflammation and necrosis. Cystadenomas frequently show many vessels along the fibrotic strands.

CONCLUSIONS

Pancreatic tumours have different vascularisation patterns in the echo-enhanced Power-Doppler sonography. These characteristics can be used for the differential diagnosis.

[Pancreatic metastases of renal cell carcinomas - evaluation of the contrast behavior at echo-enhanced power-Doppler sonography in comparison to primary pancreatic tumors]

BACKGROUND

Renal cell carcinomas are the most common primary tumors leading to pancreatic metastases. The differentiation of metastases from primary pancreatic tumors is important for the prognosis. Echo-enhanced power-Doppler sonography may be used for the differential diagnosis of tumors. In this study, the contrast behavior of metastases of renal cell carcinomas was evaluated in comparison to primary pancreatic tumors.

PATIENTS AND METHODS

Each 5 patients with pancreatic metastases of a renal cell carcinoma, a ductal carcinoma, a neuroendocrine tumor and a pancreatitis-associated mass were investigated by B-mode sonography, fundamental and echo-enhanced power-Doppler sonography.

RESULTS

Similar to neuroendocrine tumors, metastases of renal cell carcinomas were found to be hypervascularized. In contrast, ductal carcinomas are hypovascularized compared to the surrounding tissue. Tumors associated with pancreatitis show different vascularization pattern depending on inflammation and necrosis.

CONCLUSIONS

Metastases of renal cell carcinomas and ductal carcinomas show different vascularization pattern at echo-enhanced power-Doppler sonography. Renal cell metastases and neuroendocrine tumors have similar contrast behaviors, therefore, clinical symptoms should be referred for their differentiation. However, histology is the standard of reference for the differential diagnosis of pancreatic tumors.

Association between immunohistochemical expression of vascular endothelial growth factor (VEGF), VEGF-expressing neuroendocrine-differentiated tumor cells, and outcome in prostate cancer patients subjected to watchful waiting

Tumor growth is dependent on angiogenesis, which is thought to be controlled by angiogenic factors. Therefore, the immunoreactivity of the angiogenic cytokine vascular endothelial growth factor (VEGF) was semiquantitatively scored in archival prostate tumors obtained at diagnosis in 221 patients followed expectantly. At diagnosis, 125 patients suffered from clinically localized disease. Median length of follow-up was 15 years, and 57% of the patients eventually died of prostate cancer. All of the tumors exhibited cytoplasmic staining for VEGF. The staining intensity was weak in 47 tumors and moderate and strong in 107 and 67, respectively. VEGF expression was significantly correlated with microvessel density (MVD; median, 43; range, 16-151; P = 0.014), increasing T-classification (P = 0.001), dedifferentiation (P < 0.001), and disease-specific survival (P = 0.013). Strongly VEGF-immunoreactive, neuroendocrine-differentiated (NE) tumor cells were observed in 125 tumors. NE expression was significantly correlated with increasing MVD, increasing T-classification, dedifferentiation, and survival (all, P < 0.001). MVD and NE tumor cell expressions were significant variables in a multivariate analysis that included patients with clinically localized prostate cancer only. VEGF and NE expression were significantly correlated with MVD, clinical characteristics, and disease-specific survival. NE expression was a significant prognostic marker in localized prostate cancer patients, whereas the applied semiquantitatively scoring of VEGF expression was inadequate to make this growth factor provide any additional prognostic information. Moreover, the significant VEGF expression of NE tumor cells suggests an additional important character of these cells in the involvement in disease progression.

Assessment of the vascularization of neuroendocrine tumors by stimulated acoustic emission of SH U 508A ultrasound contrast agent and color or power Doppler sonography

RATIONALE AND OBJECTIVES

To assess the vascularization of neuroendocrine tumors by stimulated acoustic emission (SAE) of SH U 508A during the blood pool phase in comparison with contrast-enhanced Doppler sonography.

METHODS

Thirty-six patients with neuroendocrine tumors received contrast-enhanced Doppler sonography and 21, an additional SAE. To classify tumor perfusion on Doppler sonography, a 4-step rating score was introduced: (1) no vessels (hypoperfusion); (2) one feeding or central vessel (hypoperfusion); (3) some vessels (hyperperfusion); and (4) disseminated vessels (hyperperfusion). In 36 patients, 1 pancreatic primary tumor, 33 liver metastases, 1 splenic metastasis, and 1 lymph node metastasis were examined. Results were correlated with biphasic spiral CT (n = 35) and angiography (n = 2).

RESULTS

Arterial-phase CT and digital subtraction angiography revealed 18 hyper- and 18 hypoperfused lesions. Contrast-enhanced Doppler correctly classified 15 of 18 patients (83%) with hyperperfused lesions as well as 16 of 18 (89%) hypoperfused tumors by applying the rating score. SAE correctly identified 4 of 9 hyperperfused lesions (44%), 2 were isoperfused compared with normal liver tissue (22%), and 3 were hypoperfused (33%). Of 12 hypoperfused lesions, 11 were classified correctly (92%), and 1 showed isoperfusion. Hence, the positive and negative predictive values for SAE were 80% and 69%, respectively. For contrast-enhanced Doppler sonography, positive and negative predictive values were 88% and 84%, respectively.

CONCLUSIONS

Blood pool SAE failed to determine subtle tumor perfusion correctly. The rating score for contrast-enhanced Doppler sonography characterized tumor perfusion with high accuracy. The use of a contrast agent significantly improved perfusion characterization.

Expression of somatostatin receptors in peritumoral veins of human tumors

BACKGROUND

The vascular system of the tumor bed plays an important function in tumor growth regulation. Recent studies have suggested that the vasoactive peptides somatostatin and substance P may have a potential role in the tumor bed of selected tumors.

METHODS

In the current study, somatostatin receptors were evaluated with in vitro receptor autoradiography using 125I-[Tyr3]-octreotide in the peritumoral vessels of a large group of 215 primary human tumors and 25 metastases of various tumor origin, with particular emphasis on receptor incidence, distribution, homogeneity, and density.

RESULTS

High affinity somatostatin receptors were found in the peritumoral veins of 22 of 22 gastric carcinomas, 25 of 39 breast carcinomas, 15 of 20 renal cell carcinomas, 14 of 27 prostate carcinomas, 4 of 10 endometrial carcinomas, 4 of 11 pancreatic adenocarcinomas, 4 of 13 nonsmall cell lung carcinomas, as well as in 3 of 4 parathyroid adenomas, 3 of 3 medullary thyroid carcinomas, 3 of 23 gastroenteropancreatic tumors, 14 of 25 soft tissue tumors, 3 of 5 melanomas but in none (0 of 13) of the ovarian carcinomas studied. In addition, somatostatin receptors were identified in veins surrounding lymph node, bone, and lung metastases of various tumor types. In all investigated tissues, receptors could not be identified in arteries. There was a considerable variability in the relative number of veins expressing somatostatin receptors and in the receptor density levels. Evidence of an overexpression of somatostatin receptors could be established in the peritumoral veins of gastric carcinoma when compared with the receptor expression in normal gastric vessels.

CONCLUSIONS

The expression of somatostatin receptors in peritumoral veins appears to be a general, tumor-related, but highly variable phenomenon. Although their pathophysiologic role is unclear, these receptors may be considered as novel targets for cancer diagnosis and therapy with somatostatin analogs.

Diagnostic value of color Doppler sonography in primary liver tumors--a trend study

In order to investigate the diagnostic value in differential diagnosis of primary liver tumors, color Doppler sonography was used preoperatively in 30 patients. Without difference, tumor hypervascularization was found in patients with hepatocellular carcinoma (2 of 4), cholangiocellular carcinoma (4 of 4), hemangioma (3 of 8), focal nodular hyperplasia (8 of 8), adenoma (3 of 4), and neuroendocrine tumor (n = 1). No vascular signal could be detected in 1 case of adenomatous hyperplasia and 2 cases of hepatocellular carcinoma, one after previous chemoembolization. Hemangioma appeared hypo- or even avascular in 5 of 8 patients. Therefore, according to our experience, the yield of color Doppler sonography is rather low for differential diagnosis and prediction of the tumor dignity. With regard to the surgical procedure, valuable information about tumor extension can be obtained particularly in central lesions close to hilar structures or liver vein confluence. Further indications result from follow-up of tumor vascularization after chemoembolization and chemotherapy.