Liver metastases arising from well-differentiated pancreatic endocrine neoplasms demonstrate increased VEGF-C expression

MK2 Promotes the Development and Progression of Pancreatic Neuroendocrine Tumors Mediated by Macrophages and Metabolomic Factors

Cases of pancreatic neuroendocrine tumors (PNETs) are growing in number, and new treatment options are needed in order to improve patient outcomes. The mitogen-activated protein kinase-activated protein kinase 2 (MK2) is a crucial regulator of cytokine/chemokine production. The significance of MK2 expression and signaling pathway mediated by MK2 in PNETs has not been investigated. To characterize the impact of MK2 on PNET growth, we used the RipTag2 transgenic murine model of PNETs, and we developed a primary PNET cell line for both in vitro and in vivo studies. In the transgenic murine model of PNETs, we found that MK2 inhibition improves survival of mice and prevents PNET progression. MK2 blockade abolished cytokine/chemokine production, which was related to macrophage function. A role for MK2 in the regulation of metabolic factor secretion in PNETs was identified, making this the first study to identify a potential role for the MK2 pathway in regulation of tumor metabolism. Moreover, using an in vitro approach and allograft model of PNETs, we were able to show that macrophages with MK2 depletion exhibit increased cytotoxicity against PNET cells and substantially decreased production of pro-inflammatory cytokines and chemokines, as well as metabolic factors. Taken together, our work identifies MK2 as a potent driver of immune response and metabolic effectors in PNETs, suggesting it is a potential therapeutic target for patients with PNETs.

Translational challenges in pancreatic neuroendocrine tumor immunotherapy

Pancreatic neuroendocrine tumors are rare types of pancreatic cancer formed from islet cells of pancreas. Clinical presentation of pancreatic neuroendocrine tumors depends on both tumor progression and hormone secretion status, which generate several complications in both diagnosis and treatment. Despite numerous strategies, treatment of patients with pancreatic neuroendocrine tumors still needs improvement. It is suggested that immune response modulation may be essential in the regulation of pancreatic neuroendocrine tumor progression and patient's symptomology. Accumulating evidence indicates that immunotherapy seems to be a promising treatment option for patients with pancreatic neuroendocrine tumors. Nevertheless, several challenges in pre-clinical and clinical studies are present. This review provides knowledge about microenvironment of pancreatic neuroendocrine tumors including significance of cytokine and chemokine as well as specific immune cell types. Additionally, in vitro and in vivo models of pancreatic neuroendocrine tumors and translational challenges are highlighted.

Progress in the Management of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) are a heterogeneous and orphan group of neoplasms that vary in their histology, clinical features, prognosis, and management. The treatment of PNETs is highly dependent on the stage at presentation, tumor grade and differentiation, presence of symptoms from hormonal overproduction or from local growth, tumor burden, and rate of progression. The US Food and Drug Administration has recently approved many novel treatments, which have altered decision making and positively impacted the care and prognosis of these patients. In this review, we focus on the significant progress made in the management of PNETs over the past decade, as well as the active areas of research. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Pancreatic Neuroendocrine Tumors: Molecular Mechanisms and Therapeutic Targets

Pancreatic neuroendocrine tumors (pNETs) are unique, slow-growing malignancies whose molecular pathogenesis is incompletely understood. With rising incidence of pNETs over the last four decades, larger and more comprehensive 'omic' analyses of patient tumors have led to a clearer picture of the pNET genomic landscape and transcriptional profiles for both primary and metastatic lesions. In pNET patients with advanced disease, those insights have guided the use of targeted therapies that inhibit activated mTOR and receptor tyrosine kinase (RTK) pathways or stimulate somatostatin receptor signaling. Such treatments have significantly benefited patients, but intrinsic or acquired drug resistance in the tumors remains a major problem that leaves few to no effective treatment options for advanced cases. This demands a better understanding of essential molecular and biological events underlying pNET growth, metastasis, and drug resistance. This review examines the known molecular alterations associated with pNET pathogenesis, identifying which changes may be drivers of the disease and, as such, relevant therapeutic targets. We also highlight areas that warrant further investigation at the biological level and discuss available model systems for pNET research. The paucity of pNET models has hampered research efforts over the years, although recently developed cell line, animal, patient-derived xenograft, and patient-derived organoid models have significantly expanded the available platforms for pNET investigations. Advancements in pNET research and understanding are expected to guide improved patient treatments.

Long-term survival in a dog with primary hepatic neuroendocrine tumor treated with toceranib phosphate

Primary hepatic neuroendocrine tumors (PHNETs) are rare in dogs, and limited information exists about the treatment of these tumors. A 12-year-old castrated male French bulldog was presented to our clinic with gastrointestinal signs. Diagnostic tests revealed increased hepatic enzyme levels, a mass in the hepatic quadrate lobe, multiple intrahepatic nodules, and enlarged hepatic hilar lymph nodes. The liver mass was diagnosed cytologically as a malignant epithelial tumor suspected to be of neuroendocrine origin. The dog was treated with single-agent toceranib phosphate (TOC) and survived 25.1 months after the initial presentation. On necropsy, a liver mass was found and was subsequently diagnosed as a PHNET on histopathology. To the best of our knowledge, this is the first report of long-term survival in a dog with PHNET treated with TOC.

Vorolanib (X-82), an oral anti-VEGFR/PDGFR/CSF1R tyrosine kinase inhibitor, with everolimus in solid tumors: results of a phase I study

Background Anti-vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKI) combined with mTOR inhibitors, like everolimus, result in significant responses and prolonged progression-free survival (PFS) among patients with renal cell carcinoma (RCC) [1]. However, everolimus doses >5 mg are often not tolerated when combined with other TKIs^2,3. Vorolanib (X-82), an oral anti-VEGFR/platelet derived growth factor receptor (PDGFR)/colony stimulating factor 1 receptor (CSF1R) multitarget TKI, has a short half-life and limited tissue accumulation. We conducted a Phase 1 study of vorolanib with everolimus (10 mg daily) in patients with solid tumors. Methods A 3 + 3 dose escalation design was utilized to determine dose limiting toxicities (DLT) and recommended Phase 2 dose (RP2D) of vorolanib/everolimus. Oral vorolanib at 100, 150, 200, 300, or 400 mg was combined with 10 mg oral everolimus daily. The phase 2 portion was terminated after enrolling two patients due to funding. Results Eighteen patients were evaluable for DLT among 22 treated subjects. Observed DLTs were grade 3 fatigue, hypophosphatemia, and mucositis. The RP2D is vorolanib 300 mg with everolimus 10 mg daily. In 15 patients evaluable for response, three had partial response (PR; 2 RCC, 1 neuroendocrine tumor [NET]) and eight had stable disease (SD; 2 RCC, 6 NET). Conclusions Vorolanib can safely be combined with everolimus. Encouraging activity is seen in RCC and NET. Further studies are warranted. Trial Registration Number: NCT01784861.

Targeted Therapies in the Management of Well-Differentiated Digestive and Lung Neuroendocrine Neoplasms

OPINION STATEMENT

Ongoing advances in our understanding of neuroendocrine tumor (NET) biology, genetics, and immunology, will continue to expand the availability of targeted therapies, thus improving the outcomes of patients. Well-differentiated neuroendocrine tumors (NETs) are grouped into pancreatic and non-pancreatic NETs (includes GI and thoracic NETs) for treatment considerations (Fig. 1). For panNETs, initial therapy is driven by the need of radiographic response, and targeted agents are typically reserved for second and third line based on the toxicity profile. Treatment options for non-pancreatic NETs are also expanding and while SSAs are the typical first-line option, everolimus and PRRT both remain approved therapies for future lines, and VEGF TKIs are showing promising results in research settings. Sequencing these agents and best time to incorporate peptide receptor radio therapy into the management algorithm remains an unmet need.

Sunitinib in patients with pancreatic neuroendocrine tumors: update of safety data

Aim: To describe the long-term safety of sunitinib in patients with progressive, well-differentiated, advanced/metastatic pancreatic neuroendocrine tumors. Patients & methods: Sunitinib- and placebo-treated patients from the Phase III study continued to receive sunitinib (37.5 mg on a continuous daily-dosing regimen) in two open-label extension studies. Results: Median (range) treatment exposure: 30.2 (0.7–269.4) and 87.1 (3.9–319.4) weeks for medium-term (n = 41) and long-term-treated (n = 61) populations, respectively. All patients experienced ≥1 adverse event (AE); 47 (45.6%) reported serious AEs. Common all-causality AEs: diarrhea (63.1%); neutropenia (43.7%); abdominal pain (40.8%). Fifteen (14.6%) patients discontinued treatment due to treatment-related AEs. Conclusion: The safety of extended sunitinib treatment was consistent with the known safety profile of sunitinib in pancreatic neuroendocrine tumors.

Medical Management of Pancreatic Neuroendocrine Tumors: Current and Future Therapy

When diagnosed at an early stage, resection of pancreatic neuroendocrine tumors (NETs) is often curative. Unfortunately, curative surgery is rarely an option for patients with metastatic disease. Multiple options are available for the management of patients with advanced pancreatic NETs, including surgery, liver-directed therapy, and systemic therapies. Because of the heterogeneity of disease biology and presentation, a multidisciplinary approach to management is critical. Treatment with somatostatin analogs, sunitinib, everolimus, and alkylating agents provide effective systemic therapeutic options for patients. Future studies to evaluate the optimal timing, sequence, and combination of therapies, as well as to identify predictors of response, are warranted.

Dual inhibition of mTOR pathway and VEGF signalling in neuroendocrine neoplasms: from bench to bedside

After years of limited progress in the treatment of neuroendocrine neoplasms (NENs), an increasing number of therapeutic targets have recently emerged as potential tools to improve disease outcome. The mammalian target of rapamycin (mTOR) pathway and vascular endothelial growth factor (VEGF) signalling are implicated in the regulation of cell growth, proliferation, neo-angiogenesis and tumour cell spread. Their combined blockade, in a simultaneous or sequential strategy, represents an intriguing biological rationale to overcome the onset of resistance mechanisms. However, is becoming increasingly imperative to find the optimal sequential strategy according to the best toxicity profile, and also to identify predictive biomarkers. We will provide an overview of the pre-clinical and clinical data relating to mTOR pathway/VEGF signalling as a potential targets of treatment in NENs.

Circulating cytokines and monocyte subpopulations as biomarkers of outcome and biological activity in sunitinib-treated patients with advanced neuroendocrine tumours

BACKGROUND

Sunitinib is approved worldwide for treatment of advanced pancreatic neuroendocrine tumours (pNET), but no validated markers exist to predict response. This analysis explored biomarkers associated with sunitinib activity and clinical benefit in patients with pNET and carcinoid tumours in a phase II study.

METHODS

Plasma was assessed for vascular endothelial growth factor (VEGF)-A, soluble VEGF receptor (sVEGFR)-2, sVEGFR-3, interleukin (IL)-8 (n=105), and stromal cell-derived factor (SDF)-1α (n=28). Pre-treatment levels were compared between tumour types and correlated with response, progression-free (PFS), and overall survival (OS). Changes in circulating myelomonocytic and endothelial cells were also analysed.

RESULTS

Stromal cell-derived factor-1α and sVEGFR-2 levels were higher in pNET than in carcinoid (P=0.003 and 0.041, respectively). High (above-median) baseline SDF-1α was associated with worse PFS, OS, and response in pNET, and high sVEGFR-2 with longer OS (P⩽0.05). For carcinoid, high IL-8, sVEGFR-3, and SDF-1α were associated with shorter PFS and OS, and high IL-8 and SDF-1α with worse response (P⩽0.05). Among circulating cell types, monocytes showed the largest on-treatment decrease, particularly CD14+ monocytes co-expressing VEGFR-1 or CXCR4.

CONCLUSIONS

Interleukin-8, sVEGFR-3, and SDF-1α were identified as predictors of sunitinib clinical outcome. Putative pro-tumorigenic CXCR4+ and VEGFR-1+ monocytes represent novel candidate markers and biologically relevant targets explaining the activity of sunitinib.

Sunitinib in the treatment of advanced solid tumors

Sunitinib is an oral multikinase inhibitor that blocks the vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR) alpha and beta, c-kit, and other receptors. These attributes have proven to be efficacious in the treatment of metastatic renal cell carcinoma (RCC), unresectable gastrointestinal stromal tumors (GIST), and well-differentiated advanced pancreatic neuroendocrine tumors (PNET). Though activity has been reported in other tumor types, phase III trials have not yet demonstrated improved survival outcomes in these cancers. Most side effects including hypertension, hand-foot syndrome, and diarrhea are generally well manageable. This review will detail the preclinical data leading up to the results of the pivotal phase III clinical trials that have led to the widespread use of sunitinib in advanced RCC, GIST, and PNET.

Targeting the mTOR signaling pathway in neuroendocrine tumors

OPINION STATEMENT

Neuroendocrine tumors (NETs) are a heterogeneous group of malignancies characterized by variable but most often indolent biologic behavior. Well-differentiated NETs can be broadly classified as either carcinoid or pancreatic NET. Although they have similar characteristics on routine histologic evaluation, the 2 tumor subtypes have different biology and respond differently to treatment, with most therapeutic agents demonstrating higher response rates in pancreatic NETs compared with carcinoid. Until recently, systemic treatment options for patients with advanced NETs were limited. However, improvements in our understanding of signaling pathways involved in the pathogenesis, growth, and spread of NETs have translated into an expansion of treatment options. Aberrant signaling through the mechanistic pathway of rapamycin (mTOR) pathway has been implicated in neuroendocrine tumorigenesis. Additionally, altered expression of mTOR pathway components has been observed in NETs and has been associated with clinical outcomes. Targeting the mTOR pathway has emerged as an effective treatment strategy in the management of advanced NETs. In a randomized, placebo-controlled study of patients with advanced pancreatic NET, treatment with the mTOR inhibitor everolimus was associated with improved progression-free survival (PFS). Largely based upon these data, everolimus has been approved in the United States and Europe for the treatment of patients with advanced pancreatic NET. The activity of everolimus remains under investigation in patients with carcinoid tumors. In a randomized study of patients with advanced carcinoid tumors associated with carcinoid syndrome, the addition of everolimus to octreotide was associated with improved PFS compared with octreotide. However, the results did not meet the prespecified level of statistical significance based on central review of radiographic imaging. Results from a randomized study examining the efficacy of everolimus in patients with nonfunctional gastrointestinal and lung NETs are awaited. In addition, further investigation is needed to determine whether primary tumor site or other clinical and molecular factors can impact response to mTOR inhibition. Although everolimus can slow tumor progression, significant tumor reduction is rarely obtained. Targeting multiple signaling pathways is a treatment strategy that may provide better tumor control and overcome resistance mechanisms involved with targeting a single pathway. Results of ongoing and future studies will provide important information regarding the added benefit of combining mTOR inhibitors with other targeted agents, such as VEGF pathway inhibitors, and cytotoxic chemotherapy in the treatment of advanced NETs.

Targeted therapy with kinase inhibitors in aggressive endocrine tumors

INTRODUCTION

Kinase inhibitors (KIs) are a class of anticancer drugs that inhibit activity of the enzymes protein kinases, which regulate crucial cellular processes and have a demonstrated role in human oncogenesis. Treatment of advanced forms of endocrine cancer which are not responsive to cytotoxic chemotherapies is challenging and use of KIs is gaining a growing role in this field.

AREAS COVERED

The authors summarize the main genetic alterations known to be linked to endocrine tumors, indicating the rationale for utilizing KIs. Furthermore, they present an updated analysis of clinical trials available on PubMed Central, which were pertinent to the activities of KIs in aggressive endocrine cancer. The authors also discuss the adverse effects of KIs and summarize likely involved underlying mechanisms.

EXPERT OPINION

KIs are effective in obtaining a radiological disease control and an improvement of progression-free survival in several forms of endocrine cancer but will never deliver a knockout blow of the disease, due to mechanisms of adaptation to circumvent the specific molecular blockade. The new frontier of KIs treatment is to identify agents that could synergize activity of KIs. The true goal will be to perform an overall genotyping of each tumor, thus predicting the impact of combined targeted therapies in the context of a particular constellation of mutant genes.

Pharmacokinetics and pharmacodynamics of sunitinib for the treatment of advanced pancreatic neuroendocrine tumors

INTRODUCTION

Despite being the second most common malignancy of the pancreas, pancreatic neuroendocrine tumors (PNET) have long been understudied due to their low incidence and heterogeneous clinical presentation. Emerging data from a Phase III trial demonstrates improved progression-free survival of patients with advanced PNET on treatment with sunitinib .

AREAS COVERED

This article reviews the role of sunitinib, a multitargeted tyrosine kinase inhibitor with potent antiangiogenic and antitumor effects, in the clinical management of PNET. Furthermore, the authors also discuss the pharmacokinetics and pharmacodynamics as well as other clinically relevant aspects regarding sunitinib.

EXPERT OPINION

A recent Phase III clinical trial of sunitinib demonstrated significant improvement of progression-free survival in patients with advanced or metastatic well-differentiated PNET that led to its approval in several countries, including Europe and United States. This marks a significant step forward in the clinical management of this disease and spurs hopes to further improve overall survival in this once difficult-to-treat set of patients in the coming years. Fields of future interest will include evaluation of combinatorial regimens, including conventional cytotoxic agents as well as additional targeted drugs in order to overcome resistance to sunitinib.

Therapeutic effect of sunitinib malate and its influence on blood glucose concentrations in a patient with metastatic insulinoma

Standard cytotoxic chemotherapy has limited efficacy in advanced insulinomas, and control of blood glucose concentrations in these patients may be difficult. This article describes an elderly (74-year-old) man with metastatic insulinoma and severe hypoglycemia who was treated with repeated 6-week cycles of oral sunitinib malate (25 mg/day for 4 weeks, followed by 2 weeks off treatment). After treatment for more than 2 years, his condition improved and he continued to have a good quality of life with no evidence of tumor progression based on PET/CT findings. Although sunitinib treatment lowered the patient's blood glucose concentrations further and induced repeated symptomatic hypoglycemic episodes, he was able to tolerate the treatment well after changing the timing of sunitinib dosing and adjusting his diet.

Phase I study of sorafenib in combination with everolimus (RAD001) in patients with advanced neuroendocrine tumors

PURPOSE

Sorafenib and everolimus are both active against neuroendocrine tumors (NET). Because of potential synergy between VEGF pathway and mTOR inhibitors, we performed a phase I study to evaluate the safety and feasibility of combining sorafenib and everolimus in patients with advanced NET.

METHODS

Patients were treated with everolimus 10 mg daily in combination with sorafenib (dose level 1: 200 mg twice daily; dose level 2: 200 mg per morning, 400 mg per evening) using standard phase I dose escalation design. Dose-limiting toxicity (DLT) was defined within the first cycle (28 days) of therapy. Treatment was continued until tumor progression, unacceptable toxicity, or withdrawal of consent. Twelve additional patients were treated at the maximum tolerated dose (MTD) level to further characterize safety and a preliminary assessment of activity.

RESULTS

One patient in Cohort 1 experienced DLT (grade 3 skin rash); the cohort was expanded to 6 patients with no further DLTs. All 3 patients in Cohort 2 experienced DLT, consisting of thrombocytopenia, hand-foot skin reaction, and rash/allergic reaction. Sorafenib 200 mg twice daily in combination with everolimus 10 mg daily was established as the MTD. Independently reviewed best objective responses revealed that 62 % of patients had some degree of tumor shrinkage. By RECIST, we observed partial response in 1 patient, stable disease in 13 patients, and progressive disease in 3 patients.

CONCLUSION

Sorafenib 200 mg twice daily with everolimus 10 mg daily represents the MTD of this combination in patients with advanced NET. While the combination is active, toxicity concerns may preclude more widespread use.

Combined loss of E-cadherin and aberrant β-catenin protein expression correlates with a poor prognosis for small intestinal adenocarcinomas

Small intestinal adenocarcinomas (SIACs) are rare, and their molecular pathogenesis is largely unknown. To define the roles of E-cadherin and β-catenin, we performed immunohistochemistry for E-cadherin and β-catenin in 194 surgically resected SIACs with tissue microarrays and compared the data with clinicopathologic factors, including survival rates of patients with SIAC. Loss of E-cadherin expression and aberrant β-catenin expression were observed in 41.8% (81/194 cases) and 40.7% (79/194 cases) of SIACs, respectively. Combined loss of E-cadherin and aberrant β-catenin expression was observed in 24.2% (47/194 cases) of SIACs, and this feature was most frequently observed in mucinous adenocarcinomas and signet ring cell carcinomas (P < .001), poorly differentiated and undifferentiated carcinomas (P < .001), and tumors with advanced pT classification (P = .03). Survival times for patients with SIAC with both loss of E-cadherin and aberrant β-catenin expression (median, 13.9 months) were significantly shorter than those for patients without aberrant expression of both proteins (49.9 months), as determined by univariate (P < .001) and multivariate (P = .01) analyses. In conclusion, loss of E-cadherin and aberrant β-catenin expression correlate with poorly differentiated tumors, advanced T classification, and decreased patient survival time; therefore, it could be a prognostic factor in patients with SIAC.

Immunohistochemical endothelial markers: a review

A relatively large number of new endothelial markers that can assist in the diagnosis and classification of endothelial and vascular neoplasms have become available over the past few years. The expression of these markers, however, differs considerably among the various tumors. A selection of markers that have potential diagnostic utility or are of current interest among pathologists are reviewed and compared with some of the more traditional markers that have been employed in diagnostic pathology.

A phase II clinical trial of sunitinib following hepatic transarterial embolization for metastatic neuroendocrine tumors

BACKGROUND

The liver is the predominant site of metastases among patients with advanced neuroendocrine tumors (NETs). Prior retrospective studies have reported high response rates in patients treated with transarterial embolization (TAE). NETs are highly vascular and are known to express vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor (VEGFR). We hypothesized that administration of sunitinib, a VEGFR inhibitor, following TAE would extend progression-free survival (PFS).

PATIENTS AND METHODS

Patients with metastatic NETs to the liver underwent a series of selective TAEs followed by sunitinib (until disease progression or maximum of 12 months). Radiographic response (by RECIST), survival, and safety parameters were monitored.

RESULTS

Thirty-nine patients were enrolled. The overall response rate was 72% [95% confidence interval (CI), 0.58-0.86]. Median PFS was 15.2 months. Rates of overall survival (OS) at 1 and 4 years were 95% (95% CI, 0.88-1.00) and 59% (95% CI, 0.38-0.80), respectively. A significant 34% rise in serum VEGF was observed following the initial TAE (P = 0.03).

CONCLUSIONS

Hepatic TAE is a highly active treatment option for patients with metastatic NETs to the liver. Embolization stimulates release of VEGF into the circulation. Sunitinib, an oral VEGFR inhibitor, can be safely administered following embolization. The high rates of PFS and OS associated with this sequence of therapies are encouraging.

The novel hypoxic cytotoxin, TX-2098 has antitumor effect in pancreatic cancer; possible mechanism through inhibiting VEGF and hypoxia inducible factor-1α targeted gene expression

Tumor hypoxia has been considered to be a potential therapeutic target, because hypoxia is a common feature of solid tumors and is associated with their malignant phenotype. In the present study, we investigated the antitumor effect of a novel hypoxic cytotoxin, 3-[2-hydroxyethyl(methyl)amino]-2-quinoxalinecarbonitrile 1,4-dioxide (TX-2098) in inhibiting the expression of hypoxia inducible factor-1α (HIF-1α), and consequently vascular endothelial cell growth factor (VEGF) expression in pancreatic cancer. The antitumor effects of TX-2098 under hypoxia were tested against various human pancreatic cancer cell lines using WST-8 assay. VEGF protein induced pancreatic cancer was determined on cell-free supernatant by ELISA. Moreover, nude mice bearing subcutaneously (s.c.) or orthotopically implanted human SUIT-2 were treated with TX-2098. Tumor volume, survival and expression of HIF-1 and associated molecules were evaluated in treatment versus control groups. In vitro, TX-2098 inhibited the proliferation of various pancreatic cancer cell lines. In s.c model, tumors from nude mice injected with pancreatic cancer cells and treated with TX-2098 showed significant reductions in volume (P<0.01 versus control). Quantitative real-time reverse transcription-PCR analysis revealed that TX-2098 significantly inhibited mRNA expression of the HIF-1 associated molecules, VEGF, glucose transporter 1 and Aldolase A (P<0.01 versus control). These treatments also prolong the survival in orthotopic models. These results suggest that the effect of TX-2098 in pancreatic cancer might be correlated with the expression of VEGF and HIF-1 targeted molecules.

Therapy innovation for the treatment of pancreatic neuroendocrine tumors

INTRODUCTION

Traditional therapeutic approaches for patients with advanced neuroendocrine tumors (NETs) have included treatment with somatostatin analogs, hepatic-directed therapies, interferon and cytotoxic chemotherapy. Current knowledge about biological behavior of pancreatic neuroendocrine tumors (pNETs) has increased in the last decade, and some studies have been conducted to translate in the clinical setting. Among several molecular agents investigated in patients with progressive pNETs, everolimus and sunitinib have been studied in large Phase III trials. Both have produced significant benefit, with improvement in progression-free survival. These results were published last year by NEJM and were updated at the ASCO Annual Meeting in June 2011.

AREAS COVERED

This review focuses on the potential molecular targets in pancreatic NETs in the light of recent advances. Furthermore, it summarizes the available data for targeted agents from Phase II and III trials open to patients with this tumor.

EXPERT OPINION

These new agents are likely to play an increasingly important role in the future management of advanced pNETs. Their use in earlier phases of the disease could improve clinical outcome, avoiding side effects of the more toxic chemotherapy. The challenge in medical treatment of pNET is to define the patients who can benefit from this innovative therapy; future research should be directed to find predictive markers for response to the targeted agent.

Well-differentiated pancreatic neuroendocrine tumors: from genetics to therapy

Well-differentiated pancreatic neuroendocrine tumors (PanNETs) comprise ∼1-3% of pancreatic neoplasms. Although long considered as reasonably benign lesions, PanNETs have considerable malignant potential, with a 5-year survival of ∼65% and a 10-year survival of 45% for resected lesions. As PanNETs have a low incidence, they have been understudied, with few advances made until the completion of their exomic sequencing in the past year. In this Review, we summarize some of the latest insights into the genetics of PanNETs, and their probable implications in the context of prognosis and therapy. In particular, we discuss two genes (DAXX and ATRX) that have collectively been identified as mutated in >40% of PanNETs, and the biological and prognostic implications of these novel mutations. The identification of recurrent somatic mutations within the mTOR signaling pathway and the therapeutic implications for personalized therapy in patients with PanNETs are also discussed. Finally, this Review outlines state-of-the-art advances in the biology of PanNETs that are of emerging translational importance.

Treatment of neuroendocrine tumor liver metastases

In the care of patients with hepatic neuroendocrine metastases, medical oncologists should work in multidisciplinary fashion with surgeons, interventional radiologists, and radiation oncologists to assess the potential utility of liver-directed and systemic therapies. This paper addresses the various roles and evidence basis for cytoreductive surgery, thermal ablation (radiofrequency, microwave, and cryoablation), and embolization (bland embolization (HAE), chemoembolization (HACE), and radioembolization) as liver-directed therapies. Somatostatin analogues, cytotoxic chemotherapy, and the newer agents everolimus and suntinib are discussed as a means for controlling intra- and extrahepatic disease, along with peptide receptor radiotherapy (PRRT). Finally, the experience with orthotopic liver transplant for neuroendocrine tumors is described.

Potential synergies for combined targeted therapy in the treatment of neuroendocrine cancer

Well differentiated neuroendocrine tumours (WDNET) are a diverse group of cancers that are often advanced at the time of diagnosis and generally do not respond significantly to traditional chemotherapy. A number of intriguing therapeutic targets have emerged, including somatostatin receptors, insulin-like growth factor-1 (IGF-1) and its receptor (IGF-1R), the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway, and vascular endothelial growth factor receptor. Functional somatostatin receptors and IGF-1R as well as dysregulated mTOR--a key pathway component for both growth factor signalling and protein synthesis--have been identified in human neuroendocrine tumour (NET) cell lines. Somatostatin analogues (SSA) and mTOR inhibitors have exhibited in vitro and in vivo antitumour activity against NET and have shown effects on the IGF-1 pathway in preclinical studies. SSA inhibit PI3K/Akt signalling upstream of mTOR, suggesting that the combination of an SSA and an mTOR inhibitor may have greater efficacy than either as single agents. Recent clinical trial experience has provided some encouraging findings and prompted the design of additional studies of this dual-targeted approach to treating advanced WDNET. Results of ongoing trials of dual-targeted therapy combinations will define future therapies for advanced WDNET.

Recent advances in understanding pancreatic endocrine tumors

Pancreatic endocrine tumors (PETs) are uncommon and have an incidence of approximately 4-5 per 1 000 000 people, accounting for 1%-2% of all pancreatic neoplasms. They usually grow slowly, eventually metastasize and lead to death. PETs can be classified as functioning or non-functioning tumors based on clinical manifestation. The pathogenesis of PETs may involve abnormal expression of CD10, CD44, CD99, p27, COX2, Ki-67, KIT, CK19, ARHI, RUNX1T1, and survivin genes, loss of heterozygosity on chromosomes, hypermethylation of tumor suppressor genes, and overexpression of ghrelin. Chromogranin A (CgA) has long been used as an important broad-spectrum marker for the identification of PETs. KIT and endoglin are new independent prognostic markers for PETs. The diagnosis is based on histopathology demonstrating neuroendocrine features such as positive staining for chromogranin A and specific hormones such as gastrin, proinsulin, vasoactive intestinal peptide (VIP) and glucagon. In addition to standard localization procedures, radiology diagnosis including computed tomography (CT), positron emission tomography and computed tomography (PET/CT), magnetic resonance imaging (MRI), ultrasound (US), endoscopic ultrasound (EUS), laparoscopic ultrasound (LUS), dynamic enhanced spiral CT, selective arterial stimulation and venous sampling (ASVS), and somatostatin receptor scintigraphy (SRS) are performed. Surgery is still one of the cornerstones in the management of PETs. Laparoscopy, and drugs of somatostatin analogs are routinely used. Understanding of the recent advances of PETs has important implications for the early diagnosis and treatment of PETs.

Innovations therapy: mammalian target of rapamycin (mTOR) inhibitors for the treatment of neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare neoplasms that require a multidisciplinary approach for an optimal management. The lack of effectiveness of traditional DNA-damaging agents has led to the exploration of new targeted drugs in order to exploit phenotypical features of GEP-NET therapy. However, due to the orphan setting of these tumors, deeper characterization of molecular features and pathways that characterize cell growth, apoptosis, angiogenesis, and invasion are lacking, particularly genetic mutations or epigenetic alterations that generate oncogenic dependency or even addiction. The PI3K-AKT-mTOR pathway has been implicated as having a crucial role in GEP-NETs not only due to the overexpression of several growth factors and their receptors that finally activate this axis but also hereditary syndromes with constitutive activation of the mTOR pathway with high incidence of GEP-NETs. In this article, we aim to review the recent development of the main molecules that target mTOR complex and have showed promising activity in the treatment of GEPNETs.

Future perspectives on neuroendocrine tumors

In the last 30 years the incidence and prevalence of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) has increased substantially. This could be partly due to improvements in diagnostic imaging, which lead to the incidental diagnosis of asymptomatic cases. However, despite these improvements, patients typically experience long delays before they are diagnosed. In this review, we discuss both the limitations and advances in our understanding of the pathogenesis, molecular and cellular biology, diagnosis, classification, staging, and treatment of GEP-NETs in order to identify which factors could be contributing to the delay in diagnosis and timely treatment of these patients. Within this context, the results from the most relevant clinical trials the available targeted therapies for the treatment of GEP-NETs, such as the "RAD001 in Advanced Neuroendocrine Tumors," will be discussed.

Therapy innovations: tyrosine kinase inhibitors for the treatment of pancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) show limited sensitivity to cytotoxic agents, requiring the search for novel therapies. Recently, data from a phase III trial demonstrated that sunitinib produces a clinically significant improvement in progression-free survival in patients with unresectable, advanced, or metastatic GEP-NETs. Based on this finding, sunitinib became the first targeted drug approved for the treatment of GEP-NETs, paving the way for the approval of other anticancer agents in this drug-orphan disease. To date, results of trials involving other multitargeted tyrosine kinase inhibitors, such as sorafenib, the monoclonal antibody bevacizumab, and insulin-like growth factor 1 receptor inhibitors, have also shown promising results, and some are already being studied in phase III trials. This review updates the results of ongoing trials using inhibitors of growth factors and tyrosine kinase receptors involved in the carcinogenesis of GEP-NETs.

Sunitinib malate for the treatment of pancreatic neuroendocrine tumors

BACKGROUND

The multitargeted tyrosine kinase inhibitor sunitinib has shown activity against pancreatic neuroendocrine tumors in preclinical models and phase 1 and 2 trials.

METHODS

We conducted a multinational, randomized, double-blind, placebo-controlled phase 3 trial of sunitinib in patients with advanced, well-differentiated pancreatic neuroendocrine tumors. All patients had Response Evaluation Criteria in Solid Tumors-defined disease progression documented within 12 months before baseline. A total of 171 patients were randomly assigned (in a 1:1 ratio) to receive best supportive care with either sunitinib at a dose of 37.5 mg per day or placebo. The primary end point was progression-free survival; secondary end points included the objective response rate, overall survival, and safety.

RESULTS

The study was discontinued early, after the independent data and safety monitoring committee observed more serious adverse events and deaths in the placebo group as well as a difference in progression-free survival favoring sunitinib. Median progression-free survival was 11.4 months in the sunitinib group as compared with 5.5 months in the placebo group (hazard ratio for progression or death, 0.42; 95% confidence interval [CI], 0.26 to 0.66; P<0.001). A Cox proportional-hazards analysis of progression-free survival according to baseline characteristics favored sunitinib in all subgroups studied. The objective response rate was 9.3% in the sunitinib group versus 0% in the placebo group. At the data cutoff point, 9 deaths were reported in the sunitinib group (10%) versus 21 deaths in the placebo group (25%) (hazard ratio for death, 0.41; 95% CI, 0.19 to 0.89; P=0.02). The most frequent adverse events in the sunitinib group were diarrhea, nausea, vomiting, asthenia, and fatigue.

CONCLUSIONS

Continuous daily administration of sunitinib at a dose of 37.5 mg improved progression-free survival, overall survival, and the objective response rate as compared with placebo among patients with advanced pancreatic neuroendocrine tumors. (Funded by Pfizer; ClinicalTrials.gov number, NCT00428597.).

From targets to treatments: a review of molecular targets in pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (pancreatic NET) are relatively rare, slowly growing tumors, although their incidence is increasing, and patients may survive for several years with metastatic disease. Apart from symptomatic relief, there have been few treatment options for these tumors in the past. More recently, investigators have explored the potential of molecularly targeted agents in treating pancreatic NET, with some success. In this review, we consider the data supporting exploitation of different targets in pancreatic NET, including peptide receptors, receptor tyrosine kinases (involved in tumor angiogenesis and more directly supporting tumor growth), and intracellular targets, such as the mammalian target of rapamycin (mTOR), which has a central role in regulating cell growth, metabolism, and apoptosis. Probably due to the paucity of pancreatic NET, many clinical trials to date have included heterogeneous NET populations, and there are few randomized studies of this specific patient population. Very recently, promising results have been achieved in placebo-controlled, phase III trials with the multitargeted tyrosine kinase inhibitor, sunitinib, and the mTOR inhibitor, everolimus. These agents have been approved or are currently being reviewed by authorities for use in patients with pancreatic NET. Here we review potential molecular targets in pancreatic NET and summarize the available data for targeted agents from phase II and III trials open to patients with this tumor.

An automatic algorithm for the segmentation and morphological analysis of microvessels in immunostained histological tumour sections

A fully automatic segmentation and morphological analysis algorithm for the analysis of microvessels from CD31 immunostained histological tumour sections is presented. Development of the algorithm exploited the distinctive hues of stained vascular endothelial cells, cell nuclei and background, to provide the seeds for a 'region-growing' method for object segmentation in the 3D hue, saturation, value (HSV) colour model. The segmented objects, identified as microvessels by CD31 immunostaining, were post-processed with three morphological tasks: joining separate objects that were likely to belong to a single vessel, closing objects that had a narrow gap around their periphery, and splitting objects with multiple lumina into individual vessels. The automatic segmentation was validated against a hand-segmented set of 44 images from three different SW1222 human colorectal carcinomas xenografted into mice. 96.3 ± 0.9% of pixels were found to be correctly classified. Automated segmentation was carried out on a further 53 images from three histologically distinct mouse fibrosarcomas (MFs) for morphological comparison with the SW1222 tumours. Four morphometric measurements were calculated for each segmented vessel: vascular area (VA), ratio of lumen area to vascular area (lu/VA), eccentricity (e), and roundness (ro). In addition, the total vascular area relative to tumour tissue area (rVA) was calculated. lu/VA, e and ro were found to be significantly smaller in MF tumours than in SW1222 tumours (p < 0.05; unpaired t-test). The algorithm is available through the website http://www.caiman.org.uk where images can be uploaded, processed and sent back to users. The output from CAIMAN consists of the original image with boundaries of segmented vessels overlaid, the calculated parameters and a Matlab file, which contains the segmentation that the user can use to derive further results.

Widespread activation of the DNA damage response in human pancreatic intraepithelial neoplasia

Pancreatic intraepithelial neoplasia (PanIN) lesions are the most common non-invasive precursors of pancreatic adenocarcinoma. We postulated that accumulating DNA damage within the PanIN epithelium activates checkpoint mechanisms. Tissue microarrays were constructed from 81 surgically resected primary pancreatic adenocarcinomas and an independent set of 58 PanIN lesions (31 PanIN-1, 14 PanIN-2, and 13 PanIN-3). Immunohistochemical labeling was carried out using anti-gammaH2AX(Ser139), anti-phosphoATM(Ser1981), anti-phosphoChk2(Thr68), and anti-p53. A 'histologic score' combining area and intensity of labeling in the nuclear compartment was determined for each lesion. A progressive increase in gammaH2AX(Ser139) labeling, consistent with escalating DNA damage, was observed in the non-invasive precursor lesions (scores of 4.34, 6.21, and 7.50, respectively, for PanIN-1, -2, and -3), compared with the pancreatic ductal epithelium (score 2.36) (ANOVA, P<0.0001). In conjunction, activation of the ataxia telangiectasia mutated (ATM)-Chk2 checkpoint pathway was observed in all histological grades of PanIN lesions. Specifically, pATM(Ser1981) histologic scores for PanIN-1, PanIN-2, and PanIN-3 were 4.83, 5.14, and 7.17, respectively, versus 2.33 for the ductal epithelium (ANOVA, P<0.0001); the corresponding scores for pChk2(Thr68) were 5.43, 7.64, and 5.44 in PanINs-1, -2, and -3, respectively, versus 2.75 in the ductal epithelium (ANOVA, P<0.0001). In contrast, absent to minimal nuclear p53 was observed in the ductal epithelium, and in PanINs-1 and -2 (a histologic score of 0-1.86), with a significant upregulation (corresponding to mutational inactivation) seen only at the stage of PanIN-3 and invasive neoplasia (histologic scores of 4.00 and 4.22). Nuclear p53 accumulation in cancers was associated with attenuation of the ATM-Chk2 checkpoint and a restitution to 'baseline' levels. To conclude, activation of the ATM-Chk2 checkpoint pathway is commonly observed in PanINs, likely in response to the accumulating DNA damage from events such as oncogene mutations and telomere dysfunction. Loss of p53 function appears to be a critical determinant for bypassing this checkpoint and the subsequent progression to invasive adenocarcinoma.

Update on the molecular pathogenesis of pancreatic tumors other than common ductal adenocarcinoma

PURPOSE

Although ductal adenocarcinoma is the most common and well known pancreatic tumor type, other distinct epithelial neoplasms affecting the pancreas that show different symptoms, biological behaviors and outcomes are becoming more frequently recognized and documented. Pancreatic epithelial tumors may be separated into ductal and nonductal neoplasms. The former group includes pancreatic ductal adenocarcinoma, intraductal papillary-mucinous tumor, mucinous cystic tumor and serous cystic tumor. The latter group includes pancreatic endocrine tumor, pancreatic acinar cell carcinoma, pancreatoblastoma and solid-pseudopapillary tumor. The aim of this review is to summarize recently acquired knowledge regarding the molecular characterization of these uncommon pancreatic epithelial neoplasms.

RECENT FINDINGS

Molecular studies of uncommon pancreatic epithelial tumors suggest that the different morphological entities are associated with distinct molecular profiles, highlighting the involvement of different molecular pathways leading to the development of each subtype of pancreatic neoplasm.

CONCLUSION

The correct classification of rare pancreatic epithelial tumors and the identification of their characteristic molecular aspects is the fundamental starting point in identifying novel diagnostic molecular tools and new targets for innovative therapeutic strategies.

Pancreatic endocrine neoplasms: epidemiology and prognosis of pancreatic endocrine tumors

Pancreatic endocrine tumors (PETs) are uncommon tumors with an annual incidence <1 per 100 000 person-years in the general population. The PETs that produce hormones resulting in symptoms are designated as functional. The majority of PETs are non-functional. Of the functional tumors, insulinomas are the most common, followed by gastrinomas. The clinical course of patients with PETs is variable and depends on the extent of the disease and the treatment rendered. Patients with completely resected tumors generally have a good prognosis, and aggressive surgical therapy in patients with advanced disease may also prolong survival. The epidemiology, prognosis, and established and novel prognostic markers of PETs are reviewed.

Phase I targeted combination trial of sorafenib and erlotinib in patients with advanced solid tumors

PURPOSE

Sorafenib and erlotinib are potent, orally administered receptor tyrosine kinase inhibitors with antiproliferative and antiangiogenic activities. Given their inhibitory target profile and efficacy as single agents, the combination of these drugs is of considerable interest in solid malignancies. This study aimed to determine the recommended phase II dose of this targeted combination, their toxicity profile, pharmacokinetic interaction, and preliminary clinical activities.

EXPERIMENTAL DESIGN

Sorafenib was administered alone for a 1-week run-in period, and then both drugs were given together continuously, with every 28 days considered as a cycle. Three dose levels were assessed.

RESULTS

Seventeen patients with advanced solid tumors received 75 cycles of treatment. The most frequent adverse events of all grades were constitutional and gastrointestinal in nature followed by electrolytes and dermatologic toxicities. Fatigue was the most common adverse event (17 patients; 100%) followed by diarrhea (15 patients; 88%), hypophosphatemia (13 patients; 76%), and acneiform rash (12 patients; 71%). These adverse events were predominantly mild to moderate. The recommended phase II dose of this combination was determined as 400 mg twice daily sorafenib and 150 mg daily erlotinib. Pharmacokinetic analysis revealed no significant effect of erlotinib on the pharmacokinetic profile of sorafenib. Among 15 evaluable patients, 3 (20%) achieved a confirmed partial response and 9 (60%) had stable disease as best response.

CONCLUSIONS

Sorafenib and erlotinib are well tolerated and seem to have no pharmacokinetic interactions when administered in combination at their full single-agent recommended doses. This well tolerated combination resulted in promising activity that needs further validation in phase II studies.

Hypoxia and angiogenesis in pancreatic cancer

BACKGROUND

Pancreatic cancer remains one of the most lethal of all solid tumours of the gastrointestinal tract. It is characterized by late diagnosis, aggressive local invasion, early metastasis and resistance to chemoradiotherapy. Increasing knowledge regarding the molecular events behind the growth and invasion of pancreatic cancer may lead to new targets for intervention.

METHODS

A search of Pubmed and Medline databases was undertaken using the keywords pancreatic cancer, gastrointestinal cancer, hypoxia, angiogenesis and anti-angiogenesis therapy.

RESULTS

Hypoxia is the driving force behind angiogenesis in pancreatic cancers. Research into angiogenesis has shown many different sites that can be targeted by agents such as tyrosine kinase inhibitors.

CONCLUSION

Anti-angiogenic therapy could be an important adjunct to conventional chemotherapy treatment of gastrointestinal neoplasia.

Endocrine tumors of the pancreas

PURPOSE OF REVIEW

Neoplasms of the endocrine pancreas, commonly referenced as pancreatic islet cell tumors, are rare, often well differentiated endocrine neoplasms, whose biology remains poorly characterized. This article reviews the current clinical management of pancreatic islet cell tumors and describes the molecular events that have been studied to guide future therapies of these peculiar neoplasms.

RECENT FINDINGS

While some islet cell tumors arise in association with the MEN-1 syndrome, the majority of these neoplasms are sporadic lesions whose underlying genetic and molecular events remain largely unknown. Recent work has identified changes in gene expression occurring in metastatic and non-metastatic islet cell tumors, which appear to correlate with the occurrence of lymph node and liver metastases. Epigenetic alterations of select tumor suppressor genes may influence patient survival, and the presence of gene promoter methylation may be used as a prognostic marker system. In addition, multiple molecular alterations, including changes in expression of cellular proteins with migratory, cell cycle or angiogenic functions, have been demonstrated to influence islet cell tumor growth, invasion and metastatic spread.

SUMMARY

Understanding the molecular events underlying the biology of pancreatic islet cell tumors will aid the development of accurate prognostic markers and will guide improved therapeutic modalities in the future.

Solid-pseudopapillary neoplasms of the pancreas in men and women: do they differ?

Solid-pseudopapillary neoplasms (SPNs) of the pancreas are uncommon and occur preferentially in young women. The question whether the features of SPNs occurring in men differ from those in women has not yet been studied. For a better understanding of the clinicopathological features of SPNs of both sexes, we studied a series of 14 tumors surgically resected at a Japanese hospital within a period of 14 years. This series was composed of seven men and seven women. All these SPNs demonstrated nuclear and cytoplasmic accumulation of beta-catenin protein in immunohistochemistry and 86% of them had activating mutations of beta-catenin gene. No pancreatic neuroendocrine tumors showed such immunohistochemical findings and genetic alterations. In our series, most SPNs in women showed encapsulation by thick fibrous tissue and massive degenerative changes. Most SPNs in men exhibited solid components without prominent degenerative changes, even though they were of a similar size to those in women. These findings suggest that SPNs in men tend to be a solid mass with slower progression of degenerative changes during their growth compared to that in women. Nuclear accumulation of beta-catenin appears to be a useful marker of SPN, which allows male SPNs to be correctly diagnosed despite their less typical features.

Genes involved in neuroendocrine tumor biology

The fascinating, but often unpredictable, biology of neuroendocrine tumors (NETs) make the management of these malignancies a real challenge. The more recent development of high-throughput genomic and proteomic techniques, have opened a window to an increased knowledge of the biology of NETs. This review will discuss genes thought to play a role in the context of NE tumor biology, with particularly attention to those that may be potential new diagnostic and prognostic markers, as well as therapeutic targets. NETs constitute a heterogeneous group of neoplasm that may arise in virtually every topographic localization in the body, as a consequence of malignant transformation of various types of NE cells. Since NETs arising in the gastroenteropancreatic (GEP) or bronchopulmonary system are by far the most common, this review focuses on these entities, but lines are drawn to other NETs as well. Although large-scale gene expression analysis undoubtly have raised interesting new hypothesis concerning genes thought to play a role in tumor biology, discrepancies observed between studies and various platforms used, emphasizes the need to not only standardize the way microarray data are reported, but also to introduce standards in sample taking, processing and study design. In addition, the recognition of the complexity of the human proteome, with regard to generation of multiple isoforms from one gene, has created additional challenges. However,some goals have been reached already, as new knowledge has been translated into development of novel promising therapeutics.

Expression of hypoxia-inducible factors is correlated with the presence of a fibrotic focus and angiogenesis in pancreatic ductal adenocarcinomas

AIMS

To study the expression of hypoxia-regulated markers in pancreatic ductal adenocarcinomas (PA) in relationship to the presence of a fibrotic focus, angiogenesis quantification and clinical outcome.

METHODS AND RESULTS

The expression of hypoxia-inducible factor (HIF)-1alpha, HIF-2alpha, carbonic anhydrase 9 (CA9) and vascular endothelial growth factor (VEGF) was immunohistochemically detected in 50 PA and correlated with tumour characteristics, microvascular density (MVD) and survival. HIF-1alpha was expressed within tumour cells in 68%, HIF-2alpha in 46%, CA9 in 78% and VEGF in 52% of the cases. Stromal expression was also noted for HIF-2alpha and CA9 in, respectively, 42% and 48% of the cases. Tumour CA9 expression was associated with that of VEGF (P=0.004) and that of stromal HIF-2alpha (P=0.013), with the presence of a fibrotic focus (P=0.046) and with an increased MVD (P=0.034). Tumour VEGF expression correlated with the presence of a fibrotic focus (P=0.039) and a greater MVD (P=0.047). Both the presence of a fibrotic focus (P=0.0002) and high tumour CA9 expression (P=0.029) were associated with reduced overall survival.

CONCLUSION

The strong association of the presence of a fibrotic focus with CA9 expression and lower survival demonstrates that hypoxia-driven angiogenesis plays an important role in the progression of PA.

VEGFR-3 expression in breast cancer tissue is not restricted to lymphatic vessels

We examined the immunohistochemical reactivity for vascular endothelial growth factor receptor 3 (VEGFR-3), a protein playing an important role in lymphangiogenesis, in breast cancer. A retrospective series of 77 invasive ductal breast carcinomas was investigated. The relationship between VEGFR-3 expression and clinicopathologic parameters was examined for statistical significance using Pearson's chi-square (chi2) test and Fisher's exact test (when n<5). Threshold for significance was p<0.05. Patient age ranged from 31 to 77 years (mean: 55 years). The VEGFR-3 immunoreactivity was as follows: 5 cases were negative (6.5%), 35 + (45.4%), 27+ + (35.1%), and 10+ + + (13.0%). Reactions were positive for both lymphatic and blood vessels in several cases. VEGFR-3-positive reactions were more frequent in the tumor periphery than within the tumor. Immunoreactivity was also observed in myoepithelial cells surrounding both normal ducts and ducts with ductal carcinoma in situ. Statistical analysis of VEGFR-3 reactions was not significantly related to node status, microvessel density, and tumor grade. Ploidy showed a tendency towards significance (p=0.063); however, owing to the limited number of cases, statistical significance was not reached. VEGFR-3 lacks lymphatic vessel specificity and is also expressed in blood vessels, myoepithelial cells, and neoplastic cells.