Tumour vascular endothelial growth factor (VEGF) mRNA in relation to serum VEGF protein levels and tumour progression in human renal cell carcinoma

Gene expression and oxidative stress markers profile associated with toxic metals in patients with renal cell carcinoma

BACKGROUND

Toxic metals are associated with cancer progression. Studies have reported the relation between some toxic metals and renal cell carcinoma (RCC).

METHODS AND RESULTS

Blood levels of Cd and Pb were determined in 94 RCC patients (RCC group) and 91 matched controls as well as blood level of malondialdehyde (MDA) and catalase (CAT) activity as markers of oxidative stress and antioxidant, respectively. Gene expression of MAP kinase pathway (P38 and JNK), hypoxia-inducible factor 1-alpha (HIF1α), vascular endothelial growth factor (VEGF), cytochrome C oxidase subunit 6 (COX6), metallothionein (MT2A), and heat shock protein (HSP90AA1) were evaluated in the obtained tissue specimens. Blood Cd and Pb levels were significantly higher in RCC group comparing to control group with preferential significant increase of Cd in chromophobe RCC (chRCC) sub-type. MDA level was significantly higher and CAT activity was lower in the RCC compared to controls. The difference was evident only in chRCC. The expressions of genes were significantly increased in the cancer tissues than in non-cancerous tissues in RCC sub-types and there was a significant correlation between Cd levels and expression of genes VEGF, MT2A, P38 and JNK in chRCC group. Immunohistochemical staining of clear cell RCC tissues shows a marked expression of VEGF and HIF-1α.While COX6 staining show marked expression in chRCC.

CONCLUSIONS

There is a positive correlation between Cd toxicity and the development of RCC, especially chRCC sub-type. Cd is strongly incriminated in the pathogenesis of chRCC through the effort on some genes and oxidative stress markers.

Mathematical Model Predicts Effective Strategies to Inhibit VEGF-eNOS Signaling

The endothelial nitric oxide synthase (eNOS) signaling pathway in endothelial cells has multiple physiological significances. It produces nitric oxide (NO), an important vasodilator, and enables a long-term proliferative response, contributing to angiogenesis. This signaling pathway is mediated by vascular endothelial growth factor (VEGF), a pro-angiogenic species that is often targeted to inhibit tumor angiogenesis. However, inhibiting VEGF-mediated eNOS signaling can lead to complications such as hypertension. Therefore, it is important to understand the dynamics of eNOS signaling in the context of angiogenesis inhibitors. Thrombospondin-1 (TSP1) is an important angiogenic inhibitor that, through interaction with its receptor CD47, has been shown to redundantly inhibit eNOS signaling. However, the exact mechanisms of TSP1's inhibitory effects on this pathway remain unclear. To address this knowledge gap, we established a molecular-detailed mechanistic model to describe VEGF-mediated eNOS signaling, and we used the model to identify the potential intracellular targets of TSP1. In addition, we applied the predictive model to investigate the effects of several approaches to selectively target eNOS signaling in cells experiencing high VEGF levels present in the tumor microenvironment. This work generates insights for pharmacologic targets and therapeutic strategies to inhibit tumor angiogenesis signaling while avoiding potential side effects in normal vasoregulation.

The Influence of Breast Cancer on the Distribution of Cherry Angiomas on the Anterior Thoracic Wall: A Case Series Study

BACKGROUND/AIMS

Cherry angiomas (CAs) are one of the most common vascular manifestations of the skin. By and large, these benign lesions often only represent an aesthetic problem. In the literature, few authors have focused on the pathogenesis of these lesions, and some risk factors have been identified, such as the presence of cutaneous and non-skin neoplasias. In this study, the correlation between the distribution of CAs and breast cancer was investigated.

METHODS

We carried out a study whereby 50 women with unilateral breast cancer and the presence of CAs on the anterior thoracic wall were evaluated, with a particular focus on the difference in the number of CAs between the two haemithoraces. The data was elaborated using the Wilcoxon signed-rank test in order to evaluate whether there was a statistical significance in the distribution of CAs.

RESULTS

In 31 patients we found that the number of CAs was greater on the cancerous breast than on the contralateral one (p value <0.0001). This was confirmed both in the group of patients suffering from ductal breast cancer and in the group with early invasive breast tumours.

CONCLUSION

It is not clear whether CAs develop prior to or following breast cancer, indicating the possibility that this cutaneous manifestation could take on a predictive, prognostic development or represent only an epiphenomenon. Further in-depth studies into the pathogenesis of CAs and the relationship with breast cancer could lead to noteworthy diagnostic-therapeutic advances.

Methods for the evaluation of biomarkers in patients with kidney and liver diseases: multicentre research programme including ELUCIDATE RCT

Background

Protein biomarkers with associations with the activity and outcomes of diseases are being identified by modern proteomic technologies. They may be simple, accessible, cheap and safe tests that can inform diagnosis, prognosis, treatment selection, monitoring of disease activity and therapy and may substitute for complex, invasive and expensive tests. However, their potential is not yet being realised.

Design and methods

The study consisted of three workstreams to create a framework for research: workstream 1, methodology – to define current practice and explore methodology innovations for biomarkers for monitoring disease; workstream 2, clinical translation – to create a framework of research practice, high-quality samples and related clinical data to evaluate the validity and clinical utility of protein biomarkers; and workstream 3, the ELF to Uncover Cirrhosis as an Indication for Diagnosis and Action for Treatable Event (ELUCIDATE) randomised controlled trial (RCT) – an exemplar RCT of an established test, the ADVIA Centaur® Enhanced Liver Fibrosis (ELF) test (Siemens Healthcare Diagnostics Ltd, Camberley, UK) [consisting of a panel of three markers – (1) serum hyaluronic acid, (2) amino-terminal propeptide of type III procollagen and (3) tissue inhibitor of metalloproteinase 1], for liver cirrhosis to determine its impact on diagnostic timing and the management of cirrhosis and the process of care and improving outcomes.

Results

The methodology workstream evaluated the quality of recommendations for using prostate-specific antigen to monitor patients, systematically reviewed RCTs of monitoring strategies and reviewed the monitoring biomarker literature and how monitoring can have an impact on outcomes. Simulation studies were conducted to evaluate monitoring and improve the merits of health care. The monitoring biomarker literature is modest and robust conclusions are infrequent. We recommend improvements in research practice. Patients strongly endorsed the need for robust and conclusive research in this area. The clinical translation workstream focused on analytical and clinical validity. Cohorts were established for renal cell carcinoma (RCC) and renal transplantation (RT), with samples and patient data from multiple centres, as a rapid-access resource to evaluate the validity of biomarkers. Candidate biomarkers for RCC and RT were identified from the literature and their quality was evaluated and selected biomarkers were prioritised. The duration of follow-up was a limitation but biomarkers were identified that may be taken forward for clinical utility. In the third workstream, the ELUCIDATE trial registered 1303 patients and randomised 878 patients out of a target of 1000. The trial started late and recruited slowly initially but ultimately recruited with good statistical power to answer the key questions. ELF monitoring altered the patient process of care and may show benefits from the early introduction of interventions with further follow-up. The ELUCIDATE trial was an ‘exemplar’ trial that has demonstrated the challenges of evaluating biomarker strategies in ‘end-to-end’ RCTs and will inform future study designs.

Conclusions

The limitations in the programme were principally that, during the collection and curation of the cohorts of patients with RCC and RT, the pace of discovery of new biomarkers in commercial and non-commercial research was slower than anticipated and so conclusive evaluations using the cohorts are few; however, access to the cohorts will be sustained for future new biomarkers. The ELUCIDATE trial was slow to start and recruit to, with a late surge of recruitment, and so final conclusions about the impact of the ELF test on long-term outcomes await further follow-up. The findings from the three workstreams were used to synthesise a strategy and framework for future biomarker evaluations incorporating innovations in study design, health economics and health informatics.

Trial registration

Current Controlled Trials ISRCTN74815110, UKCRN ID 9954 and UKCRN ID 11930.

Funding

This project was funded by the NIHR Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 6, No. 3. See the NIHR Journals Library website for further project information.

Phase I dose-escalation study of pazopanib combined with bevacizumab in patients with metastatic renal cell carcinoma or other advanced tumors

BACKGROUND

Vascular endothelial growth factor (VEGF) directed therapies are being used in a large number of advanced tumors. Metastatic renal cell carcinoma (mRCC) is highly dependent on the VEGF pathway; VEGF receptor (VEGFR) tyrosine kinase inhibitors (TKI) and humanized VEGF monoclonal antibody have been registered for clinical use in advanced renal cell carcinoma. The VEGFR TKI, pazopanib, with a rather manageable toxicity profile, was preferred to sunitinib by mRCC patients. We investigate the combination of pazopanib and bevacizumab to determine the maximum tolerated dose (MTD) in mRCC and other advanced solid tumors.

METHODS

In this bicentric phase I trial with a 3 + 3 + 3 dose-escalation design, patients received oral pazopanib once daily plus intravenous infusion of bevacizumab every 2 weeks from D15, at one of the four dose levels (DL) planned according to the occurrence of dose limiting toxicities (DLT). 400 and 600 mg pazopanib were respectively combined with 7.5 mg/kg bevacizumab in DL1 and DL2, and 600 and 800 mg pazopanib with 10 mg/kg bevacizumab in DL3 and DL4. Tumor response was evaluated every 8 weeks. Blood samples were assayed to investigate pazopanib pharmacokinetics.

RESULTS

Twenty five patients including seven mRCC were enrolled. Nine patients received the DL1, ten received the DL2. No DLT were observed at DL1, five DLT at DL2, and 3 DLT in the six additional patients who received the DL1. A grade 3 microangiopathic hemolytic anemia syndrome was observed in four (16%) patients. Five (22%) patients achieved a partial response. The mean (range) plasmatic concentrations of 400 and 600 pazopanib were respectively 283 (139-427) and 494 (227-761) μg.h/mL at Day 1, and 738 (487-989) and 1071 (678-1464) μg.h/mL at Day 15 i.e. higher than those previously reported with pazopanib, and were not directly influenced by bevacizumab infusion.

CONCLUSIONS

The combination of pazopanib and bevacizumab induces angiogenic toxicity in patients without any pre-existing renal or vascular damage. Even if a marginal efficacy was reported with five (22%) patients in partial response in different tumor types, the toxicity profile compromises the development of this combination.

TRIAL REGISTRATION

The study was retrospectively registered on ClinicalTrials.gov (number NCT01202032 ) on 2010, Sept 14th.

Compartment model predicts VEGF secretion and investigates the effects of VEGF trap in tumor-bearing mice

Angiogenesis, the formation of new blood vessels from existing vasculature, is important in tumor growth and metastasis. A key regulator of angiogenesis is vascular endothelial growth factor (VEGF), which has been targeted in numerous anti-angiogenic therapies aimed at inhibiting tumor angiogenesis. Systems biology approaches, including computational modeling, are useful for understanding this complex biological process and can aid in the development of novel and effective therapeutics that target the VEGF family of proteins and receptors. We have developed a computational model of VEGF transport and kinetics in the tumor-bearing mouse, which includes three-compartments: normal tissue, blood, and tumor. The model simulates human tumor xenografts and includes human (VEGF121 and VEGF165) and mouse (VEGF120 and VEGF164) isoforms. The model incorporates molecular interactions between these VEGF isoforms and receptors (VEGFR1 and VEGFR2), as well as co-receptors (NRP1 and NRP2). We also include important soluble factors: soluble VEGFR1 (sFlt-1) and α-2-macroglobulin. The model accounts for transport via macromolecular transendothelial permeability, lymphatic flow, and plasma clearance. We have fit the model to available in vivo experimental data on the plasma concentration of free VEGF Trap and VEGF Trap bound to mouse and human VEGF in order to estimate the rates at which parenchymal cells (myocytes and tumor cells) and endothelial cells secrete VEGF. Interestingly, the predicted tumor VEGF secretion rates are significantly lower (0.007-0.023 molecules/cell/s, depending on the tumor microenvironment) than most reported in vitro measurements (0.03-2.65 molecules/cell/s). The optimized model is used to investigate the interstitial and plasma VEGF concentrations and the effect of the VEGF-neutralizing agent, VEGF Trap (aflibercept). This work complements experimental studies performed in mice and provides a framework with which to examine the effects of anti-VEGF agents, aiding in the optimization of such anti-angiogenic therapeutics as well as analysis of clinical data. The model predictions also have implications for biomarker discovery with anti-angiogenic therapies.

Effect of tumor microenvironment on tumor VEGF during anti-VEGF treatment: systems biology predictions

BACKGROUND

Vascular endothelial growth factor (VEGF) is known to be a potent promoter of angiogenesis under both physiological and pathological conditions. Given its role in regulating tumor vascularization, VEGF has been targeted in various cancer treatments, and anti-VEGF therapy has been used clinically for treatment of several types of cancer. Systems biology approaches, particularly computational models, provide insight into the complexity of tumor angiogenesis. These models complement experimental studies and aid in the development of effective therapies targeting angiogenesis.

METHODS

We developed an experiment-based, molecular-detailed compartment model of VEGF kinetics and transport to investigate the distribution of two major VEGF isoforms (VEGF121 and VEGF165) in the body. The model is applied to predict the dynamics of tumor VEGF and, importantly, to gain insight into how tumor VEGF responds to an intravenous injection of an anti-VEGF agent.

RESULTS

The model predicts that free VEGF in the tumor interstitium is seven to 13 times higher than plasma VEGF and is predominantly in the form of VEGF121 (>70%), predictions that are validated by experimental data. The model also predicts that tumor VEGF can increase or decrease with anti-VEGF treatment depending on tumor microenvironment, pointing to the importance of personalized medicine.

CONCLUSIONS

This computational study suggests that the rate of VEGF secretion by tumor cells may serve as a biomarker to predict the patient population that is likely to respond to anti-VEGF treatment. Thus, the model predictions have important clinical relevance and may aid clinicians and clinical researchers seeking interpretation of pharmacokinetic and pharmacodynamic observations and optimization of anti-VEGF therapies.

Predicting the effects of anti-angiogenic agents targeting specific VEGF isoforms

Vascular endothelial growth factor (VEGF) is a key mediator of angiogenesis, whose effect on cancer growth and development is well characterized. Alternative splicing of VEGF leads to several different isoforms, which are differentially expressed in various tumor types and have distinct functions in tumor blood vessel formation. Many cancer therapies aim to inhibit angiogenesis by targeting VEGF and preventing intracellular signaling leading to tumor vascularization; however, the effects of targeting specific VEGF isoforms have received little attention in the clinical setting. In this work, we investigate the effects of selectively targeting a single VEGF isoform, as compared with inhibiting all isoforms. We utilize a molecular-detailed whole-body compartment model of VEGF transport and kinetics in the presence of breast tumor. The model includes two major VEGF isoforms, VEGF(121) and VEGF(165), receptors VEGFR1 and VEGFR2, and co-receptors Neuropilin-1 and Neuropilin-2. We utilize the model to predict the concentrations of free VEGF, the number of VEGF/VEGFR2 complexes (considered to be pro-angiogenic), and the receptor occupancy profiles following inhibition of VEGF using isoform-specific anti-VEGF agents. We predict that targeting VEGF(121) leads to a 54% and 84% reduction in free VEGF in tumors that secrete both VEGF isoforms or tumors that overexpress VEGF(121), respectively. Additionally, 21% of the VEGFR2 molecules in the blood are ligated following inhibition of VEGF(121), compared with 88% when both isoforms are targeted. Targeting VEGF(121) reduces tumor free VEGF and is an effective treatment strategy. Our results provide a basis for clinical investigation of isoform-specific anti-VEGF agents.

Pharmacokinetics and pharmacodynamics of VEGF-neutralizing antibodies

Background

Vascular endothelial growth factor (VEGF) is a potent regulator of angiogenesis, and its role in cancer biology has been widely studied. Many cancer therapies target angiogenesis, with a focus being on VEGF-mediated signaling such as antibodies to VEGF. However, it is difficult to predict the effects of VEGF-neutralizing agents. We have developed a whole-body model of VEGF kinetics and transport under pathological conditions (in the presence of breast tumor). The model includes two major VEGF isoforms VEGF₁₂₁ and VEGF₁₆₅, receptors VEGFR1, VEGFR2 and co-receptors Neuropilin-1 and Neuropilin-2. We have added receptors on parenchymal cells (muscle fibers and tumor cells), and incorporated experimental data for the cell surface density of receptors on the endothelial cells, myocytes, and tumor cells. The model is applied to investigate the action of VEGF-neutralizing agents (called "anti-VEGF") in the treatment of cancer.

Results

Through a sensitivity study, we examine how model parameters influence the level of free VEGF in the tumor, a measure of the response to VEGF-neutralizing drugs. We investigate the effects of systemic properties such as microvascular permeability and lymphatic flow, and of drug characteristics such as the clearance rate and binding affinity. We predict that increasing microvascular permeability in the tumor above 10^-5 cm/s elicits the undesired effect of increasing tumor interstitial VEGF concentration beyond even the baseline level. We also examine the impact of the tumor microenvironment, including receptor expression and internalization, as well as VEGF secretion. We find that following anti-VEGF treatment, the concentration of free VEGF in the tumor can vary between 7 and 233 pM, with a dependence on both the density of VEGF receptors and co-receptors and the rate of neuropilin internalization on tumor cells. Finally, we predict that free VEGF in the tumor is reduced following anti-VEGF treatment when VEGF₁₂₁ comprises at least 25% of the VEGF secreted by tumor cells.

Conclusions

This study explores the optimal drug characteristics required for an anti-VEGF agent to have a therapeutic effect and the tumor-specific properties that influence the response to therapy. Our model provides a framework for investigating the use of VEGF-neutralizing drugs for personalized medicine treatment strategies.

Potential use of circulating endothelial cells as a biomarker of renal cell carcinoma

Each year, renal cell carcinoma (RCC) accounts for significant mortality in the population. Whilst the disease is now being diagnosed earlier, determining patient prognosis remains a challenge. Current prognostic indicators, such as TNM stage, Fuhrman grade, and RCC subtype, are inadequate. Unlike several other malignancies, RCC lacks a biomarker that can stratify patients into high, intermediate, or low risk for developing metastases. Additionally, antiangiogenic therapy is currently offered to patients with metastatic disease, however, a biomarker to monitor treatment efficacy is lacking. Recent attention has focused on surrogate markers of tumor vascularization as a source of prognostic biomarkers, as tumor growth is ultimately dependent on neovascularization. Two cell populations of interest, circulating endothelial cells (CECs) and circulating endothelial progenitors (CEPs), have been demonstrated across several studies to contribute to tumor vascularization. Given these findings, studies have examined their utility as biomarkers of prognosis by correlating their levels with progression-free survival and prognostic determinants such as tumor volume and weight. However, their role in predicting prognosis in RCC, as well as their potential to act as markers of treatment efficacy in metastatic RCC, remains to be established. Previous studies on CECs and CEPs in the context of cancer will be outlined in this review.

Vascular endothelial growth factor and its type 2 receptor in tumors and serum of patients with renal cancer

It was found that renal cancer tissue is characterized by increased content of VEGF not depending on the parameters of normal tissue and expression of VEGFR2 receptor. At the same time, the content of VEGFR2 in the tumor is determined by the state of the surrounding tissue and increases in low number of patients with tumors invading the renal capsule. Serum concentrations of VEGF and VEGFR2 in patients with renal cancer did not significantly differ from the corresponding values in the control group. No significant correlations between the levels of VEGF and VEGFR2 in the blood and tumor tissue were found.

Phase I trial of bevacizumab plus escalated doses of sunitinib in patients with metastatic renal cell carcinoma

PURPOSE

Both bevacizumab and sunitinib target the vascular endothelial growth factor pathway and demonstrate activity against advanced renal cell carcinoma (RCC). In this phase I study, the maximum-tolerated dose (MTD) and safety of sunitinib in combination with bevacizumab were examined in patients with advanced RCC.

PATIENTS AND METHODS

Three cohorts of three to six patients were treated with escalated doses of daily oral sunitinib (ie, 25 mg, 37.5 mg, 50 mg) for 4 weeks followed by a 2-week break and with fixed doses of bevacizumab (10 mg/kg) intravenously once every 2 weeks. Dose-limiting toxicities (DLTs) were assessed during the first cycle to determine the MTD, and an expanded cohort was treated to obtain additional safety information.

RESULTS

Of 26 study participants, 25 received treatment at one of three dose levels. Grade 4 hemorrhage, identified as a DLT, occurred in one patient in each of cohorts 2 and 3. The MTD was determined to be sunitinib 50 mg/bevacizumab 10 mg/kg, but chronic therapy at this dose level frequently resulted in grades 3 to 4 hypertension and hematologic and vascular toxicities. Overall, 48% of patients discontinued treatment because of adverse events. One complete and 12 partial responses were observed, which provided an objective response rate of 52%.

CONCLUSION

In this phase I trial of patients with metastatic RCC, the combination of sunitinib and bevacizumab caused a high degree of hypertension and vascular and hematologic toxicities at the highest dose level. We do not plan to pursue additional study of this regimen at these doses in patients with RCC.

VEGF, COX-2, and PCNA expression in renal cell carcinoma subtypes and their prognostic value

OBJECTIVE

To evaluate the prognostic value of new markers such as VEGF (vascular endothelial growth factor), COX-2 (cyclooxygenase-2), and PCNA (proliferating cell nuclear antigen) and review their differences in expression by histological subtype in patients with renal cell carcinoma (RCC).

METHODS

About 99 patients who underwent radical (n = 79) or partial nephrectomy (n = 20) were included in this study. Histopathological specimens from the subjects were retrospectively analyzed immunohistochemically for the presence of VEGF, COX-2, or PCNA.

RESULTS

Mean staining ratios for VEGF, COX-2, and PCNA were 16.5, 16.8, and 31%, respectively. Correlations were evaluated among these three prognostic factors. There was no correlation between PCNA and VEGF (P = .068), but there were significant correlations between COX-2 and both PCNA and VEGF (P = .005 and P = .000, respectively). A significant correlation was found between the expression of VEGF and both pathologic stage and vascular invasion (P = .018 and P = .025, respectively). In addition, patients with conventional RCC had significantly lower VEGF and COX-2 levels than those with papillary RCC (P < .012).

CONCLUSIONS

It is obvious that prognostic factors such as VEGF, COX-2, and PCNA may vary depending on histological subtype. The level of expression of these factors together with histological subtype may provide valuable predictive information about the outcome of treatment.

VEGF and VEGFR-1 are coexpressed by epithelial and stromal cells of renal cell carcinoma

BACKGROUND

Tumor angiogenesis is a dynamic process that plays a major role in cancer progression. Vascular endothelial growth factor (VEGF) and its receptors play a pivotal role in angiogenesis. The expression of VEGF and its receptors VEGFR-1 and VEGFR-2 in renal cell carcinoma (RCC) was investigated in the perspective of anti-VEGF treatments.

METHODS

Total VEGF protein levels were quantified by enzyme-linked immunosorbent assay (ELISA) in tumor tissue samples from surgical specimens of 65 patients with clear cell RCC. At the cellular level the VEGF isoforms VEGFR-1 and VEGFR-2 mRNA were quantified by real-time quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) in laser-microdissected tumoral epithelial as stromal cells and in corresponding normal tissue compartments. Colocalization of VEGF and VEGFR-1 proteins was studied by triple immunofluorescent labeling.

RESULTS

Protein VEGF in cytosolic extracts was significantly higher in tumoral than in nontumoral tissue (P< .0001). Event-free survival was significantly longer for patients with cytosolic VEGF lower than the cutoff (75th percentile of VEGF protein levels, P= .02). In laser-microdissected epithelial cells, VEGF(121) and VEGFR-1 mRNA expressions were higher in RCC than in corresponding nontumoral kidney (P= .007 and P= .002, respectively); they were also higher in stromal cells of RCC compared with nontumoral kidney (P= .02 and P= .003, respectively). There was no differential VEGFR-2 expression in epithelial or in stromal cells of tumoral or nontumoral kidney. By immunofluorescent labeling VEGF and VEGFR-1 colocalized on RCC tumor epithelial and stromal cells.

CONCLUSIONS

Combined laser microdissection and quantitative RT-PCR, as triple immunofluorescent labeling, underlined the preferential expression of the most soluble VEGF isoform, VEGF(121), and its receptor VEGFR-1, but not VEGFR-2, in epithelial and stromal cells of RCC.

Where is VEGF in the body? A meta-analysis of VEGF distribution in cancer

Vascular endothelial growth factor (VEGF) is a major target for the inhibition of tumour vascularisation and the treatment of human cancer. Many tumours produce large quantities of VEGF, and as a result, diagnosis and prognosis of cancer may be predicted by measuring changes in VEGF concentrations in blood. In blood, the VEGF may be located in the plasma, or in the blood-borne cells and formed elements, in particular, platelets and leukocytes. In this study, we collate the measurements of VEGF in platelets, leukocytes, plasma and serum for breast, prostate, colorectal and other cancers. In addition, we analysed the concentration of VEGF in tumour tissue itself, as well as for other tissues in the human body. Although the concentration of VEGF in tumours is high, the size of tumours is small compared to other tissues, in particular, skeletal muscle. Thus, the total quantity of VEGF in tumours and in blood is small compared to the quantity in muscles. This large reservoir of VEGF may have important implications for the treatment of cancer.

Where is VEGF in the body? A meta-analysis of VEGF distribution in cancer

Vascular endothelial growth factor (VEGF) is a major target for the inhibition of tumour vascularisation and the treatment of human cancer. Many tumours produce large quantities of VEGF, and as a result, diagnosis and prognosis of cancer may be predicted by measuring changes in VEGF concentrations in blood. In blood, the VEGF may be located in the plasma, or in the blood-borne cells and formed elements, in particular, platelets and leukocytes. In this study, we collate the measurements of VEGF in platelets, leukocytes, plasma and serum for breast, prostate, colorectal and other cancers. In addition, we analysed the concentration of VEGF in tumour tissue itself, as well as for other tissues in the human body. Although the concentration of VEGF in tumours is high, the size of tumours is small compared to other tissues, in particular, skeletal muscle. Thus, the total quantity of VEGF in tumours and in blood is small compared to the quantity in muscles. This large reservoir of VEGF may have important implications for the treatment of cancer.

Safety, pharmacokinetics, and preliminary antitumor activity of sorafenib: a review of four phase I trials in patients with advanced refractory solid tumors

Sorafenib is an oral multikinase inhibitor that inhibits Raf serine/threonine kinases and receptor tyrosine kinases involved in tumor growth and angiogenesis. It has demonstrated preclinical and clinical activity in several tumor types. Sorafenib 400 mg twice daily (bid) has been approved in several countries worldwide for the treatment of renal cell carcinoma. This review summarizes key safety, pharmacokinetic, and efficacy data from four phase I, single-agent, dose-escalation studies with sorafenib in patients with advanced refractory solid tumors (n = 173). These trials followed different treatment regimens (7 days on/7 days off, n = 19; 21 days on/7 days off, n = 44; 28 days on/7 days off, n = 41; or continuous dosing, n = 69) to establish the optimum dosing schedule. Sorafenib was generally well tolerated; most adverse events were mild to moderate in severity up to the defined maximum-tolerated dose of 400 mg twice daily (bid). The most frequently reported drug-related adverse events at any grade included fatigue (40%), anorexia (35%), diarrhea (34%), rash/desquamation (27%), and hand-foot skin reaction (25%). Sorafenib demonstrated preliminary antitumor activity, particularly among patients with renal cell carcinoma or hepatocellular carcinoma: overall, two of 137 evaluable patients achieved partial responses and 38 (28%) had stable disease. Although there was high interpatient variability in plasma pharmacokinetics across these studies, this was not associated with an increased incidence or severity of toxicity. Preliminary studies suggest that phosphorylated extracellular signal-related kinase in tumor cells or peripheral blood lymphocytes may be a useful biomarker for measuring and, ultimately, predicting the effects of sorafenib. Based on these findings, continuous daily 400 mg bid sorafenib was chosen as the optimal regimen for phase II/III studies. Trials are ongoing in renal cell carcinoma, hepatocellular carcinoma, melanoma, and non-small cell lung cancer.

Evaluation of CD31 (PECAM-1) expression using tissue microarray in patients with renal cell carcinoma

Intratumoural microvessel density (MVD) has prognostic significance in selected neoplasms. To evaluate the prognostic information of MVD in renal cell carcinoma (RCC) we assessed the immunohistochemical expression of CD31 in 208 tumours using the tissue microarray technique. The expression was related to tumour cell type, TNM stage, nuclear grade and survival. CD31 expression was significantly (p < 0.001) higher in 167 conventional RCCs (clear cell) compared to 28 papillary RCCs. In conventional RCC, CD31 expression was inversely correlated to TNM stage (p = 0.024) and nuclear grade (p = 0.010). To evaluate the impact of CD31 expression on tumour-specific survival, the conventional RCC tumours were subdivided into quartiles according to the CD31 expression. In univariate analysis, patients with tumours in the quartile with the highest expression had a more favourable prognosis (p = 0.01) compared to those with lower CD31 expression. A multivariate analysis of prognostic factors in conventional RCC showed that TNM stage and nuclear grade were independent predictors of prognosis, but CD31 expression did not add further prognostic information.

Targeted therapy for renal cell carcinoma: a new therapeutic paradigm

Renal cell carcinoma is the most common tumor of the kidney. It has an unpredictable behavior and poor response to systemic therapy. Developing newer therapy for this disease is a priority considering the high recurrence rate and the small subset of patients who benefit from the use of cytokines such as interferon-alpha or interleukin-2. Identifying molecular targets and targeting various biomarkers has revolutionized the therapeutic approach to advanced and metastatic renal cell carcinoma. Although some of the antiangiogenic agents and receptor tyrosine kinase inhibitors appear promising, further understanding of their mechanism of action and the patient population who would benefit most from such agents is still being explored. As numerous targeted agents are entering the clinical investigation arena in a relatively short period of time, newer challenges in renal cell carcinoma therapeutics are emerging. Some of the future challenges in using targeted antineoplastic agents in renal cell carcinoma will include evaluating their long-term safety and benefit, using the particular drug in the appropriate patient population after appropriate stratification and studying the combination of some of these drugs for synergy or additive effects.

Different vascular endothelial growth factor (VEGF), VEGF-receptor 1 and -2 mRNA expression profiles between clear cell and papillary renal cell carcinoma

OBJECTIVES

To examine vascular endothelial growth factor (VEGF), VEGF-receptor-(R)1, and R2 mRNA levels in renal cell carcinoma (RCC), a tumour generally refractory to most medical therapy, but for which a potentially useful therapeutic alternative is inhibition of angiogenesis.

PATIENTS AND METHODS

VEGF, VEGF-R1 and -R2 mRNA levels were analysed using the quantitative reverse transcription-polymerase chain reaction. RNA was extracted from 84 conventional (clear cell) RCCs (cRCC), 20 papillary (pRCC), six chromophobe (chRCC), and 27 corresponding kidney cortex tissues, obtained from 110 patients in whom high-quality RNA was available from the tumours (53 women and 57 men, mean age 64.7 years, range 25-85).

RESULTS

The VEGF, VEGF-R1, and -R2 mRNA levels were higher in tumour than in kidney cortex tissues. Among the RCC types, cRCC had higher VEGF levels than pRCC. In cRCC, VEGF-R2 levels were higher in stage I-II than in more advanced stages. In pRCC, VEGF and VEGF-R2 levels were higher in stage III than in stage I-II tumours. In cRCC, patients with VEGF levels below the median had a significantly shorter survival time than those with higher levels. By contrast, in pRCC, VEGF, VEGF-R1 and -R2 RNA levels above the median were related to adverse survival. Using multivariate analysis in cRCCs, VEGF-R1 mRNA level was the last factor to be omitted after stepwise elimination analysis.

CONCLUSION

VEGF and its receptors were associated with tumour stage and survival, but were not independent prognostic factors. Different RCC types had different expression patterns of VEGF and receptor mRNA levels. We conclude that different pathways might be involved in regulating angiogenesis in the specific RCC types. Detailed knowledge of angiogenesis in RCC is essential when designing new treatment trials where angiogenesis inhibition is used.

Adrenocortical carcinoma

PURPOSE OF REVIEW

Adrenocortical carcinoma is a rare malignancy, accounting for 0.02% of all annual cancers reported. Given the generally advanced stage at diagnosis, the overall 5-year survival remains poor, varying between 20 and 45%. While older studies purported an improved outcome for functional tumors in adult patients, this has not been borne out in more recent studies. In the pediatric population, though, virilizing tumors carry a better survival than non-functional or cortisol-secreting tumors.

RECENT FINDINGS

Recent studies focusing on the tumorigenesis of adrenocortical carcinoma have focused on onco-developmental genes present in the fetal adrenal cortex, as well as local adrenal paracrine and autocrine effects of cellular peptides.

SUMMARY

Pre-operative diagnostic advances in positron emission scanning are emerging as promising modalities for confirmation of malignancy of indeterminate adrenal masses. No significant advances in the treatment of adrenocortical carcinoma have been developed. Surgery remains the mainstay for primary and recurrent disease, including select patients with isolated liver metastases. Mitotane has remained the preferred adjuvant treatment agent, showing modest effect in patients with unresectable, residual or metastatic disease. Multi-institutional registries and trials need to be established, with multidisciplinary efforts focused on the development of new therapeutic strategies.

Hypoxia-inducible factor 1alpha expression in renal cell carcinoma analyzed by tissue microarray

OBJECTIVES

Angiogenesis is important for tumour progression and metastatic spread. Hypoxia-inducible factor 1alpha (HIF-1alpha) is a major factor regulating a number of other angiogenic factors. Renal cell carcinoma (RCC) is a malignancy with a variable clinical course, partly attributable to specific genetic alterations of the different RCC types. We therefore analysed HIF-1alpha expression using immunohistochemistry and related the results to RCC type and clinicopathologic variables.

MATERIAL AND METHODS

We semiquantitatively analysed HIF-1alpha expression using immunohistological staining of a prepared tissue microarray. There were 216 patients including 176 conventional, 26 papillary, and 14 chromophobe RCCs.

RESULTS

The HIF-1alpha staining was found mainly in the cytoplasm. The tumours were subdivided into HIF-1alpha(LOW) and HIF-1alpha(HIGH) on the basis of staining intensity. HIF-1alpha expression between the RCC types did not differ. Patients with conventional RCC showed a trend (p=0.055) towards a prolonged survival for those with HIF-1alpha(HIGH)-staining versus HIF-1alpha(LOW)-staining tumors. In conventional RCC there were significant differences in HIF-1alpha expression in relation to TNM stage, nuclear grade, and vein invasion. In patients with papillary RCC, difference in HIF-1alpha expression was observed only for nuclear grade.

CONCLUSIONS

We studied HIF-1alpha expression in RCC using tissue microarray. In patients with conventional RCC, HIF-1alpha levels were significantly lower in locally aggressive tumors versus localized tumors, and patients with high HIF-1alpha levels tended to have a better prognosis. There seems to be a diverging regulation of angiogenesis between the different RCC types. Further studies of HIF and angiogenesis in RCC are encouraged.

Different isoform patterns for vascular endothelial growth factor between clear cell and papillary renal cell carcinoma

OBJECTIVE

To investigate the protein expression of vascular endothelial growth factor (VEGF) isoforms in relation to the clinical course in patients with different renal cell carcinoma (RCC) types, as angiogenesis is essential for tumour growth and metastasis.

PATIENTS AND METHODS

Western blots were assayed of protein extracts from tumour and concomitant kidney cortex samples from 96 patients. The levels of VEGF189, VEGF165, and VEGF121 isoforms were correlated with clinicopathological characteristics and survival.

RESULTS

VEGF189 levels were significantly higher in kidney cortex and chromophobe RCC than in papillary and conventional RCC. In papillary RCCs, VEGF189 levels correlated inversely with tumour stage and tumour size. VEGF165 levels were higher in kidney cortex than in RCC, but there was no difference among the RCC types. VEGF121 expression was associated with less advanced tumour stage in conventional RCC. Using multivariate analysis, VEGF189 remained as an independent prognostic factor for patients with papillary RCC.

CONCLUSIONS

VEGF189 was associated with tumour progression; in papillary RCC, VEGF189 was a significant independent prognostic factor. VEGF protein isoform patterns differed among the specific RCC types. Additional knowledge is essential to design new anti-angiogenic therapies for all RCC types.

Understanding the Importance of Smart Drugs in Renal Cell Carcinoma

OBJECTIVE

To understand the mode of action of the currently most investigated new drugs in renal cell carcinoma (RCC) and ultimately to analyze what should be the role of the urologist in this new therapeutic era.

METHODS

A comprehensive review of the peer-reviewed literature was performed on the topic of molecular pathways involved in RCC angiogenesis, vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor (VEGFR) and targeted molecular therapy for RCC.

RESULTS

Von Hippel-Lindau (VHL) disease has provided a model for understanding that the early inactivation of the VHL gene was responsible for accumulation of hypoxia-inducible factor and therefore activation of hypoxia-inducible genes such as VEGF, platelet-derived growth factor, erythropoietin, carbonic anhydrase IX and tumor growth factor alpha. The fact that such VHL inactivation also was found in up to 70% of sporadic RCC has been the rationale for developing new drugs targeting VEGF, VEGFR, platelet-derived growth factor receptor and tyrosine kinase receptors that are required for intracellular transduction.

CONCLUSION

Initial results from phase 2 trials in metastatic disease are very promising. There is a strong rationale for initiating adjuvant trials with those kind of agents in patients with high-risk localised tumors. Urologists who have a good understanding of prognostic parameters in localised RCC particularly should be involved in such new approaches.

Oligonucleotides used as template calibrators for general application in quantitative polymerase chain reaction

The optimizing and controlling for polymerase chain reactions (PCRs) requires standard target sequences to measure reaction specificity and to obtain accurate gene quantification. However, defined target sequences are often not readily available. This situation is particularly evident in the study of rare splice variant transcripts. For gains in efficiency and reaction speed, a small size of PCR amplicon typifies real-time PCR formats, including hydrolysis probes. This study demonstrates the use of oligonucleotides resembling one strand of complete amplicon sequences used in real-time PCR to provide sustainable and precise amounts of the target sequence without the necessity of enlisting nucleic acid cloning procedures. The application of template oligonucleotides is modeled using all of the splice variant forms of human vascular endothelial growth factor.

Safety and pharmacokinetics of the dual action Raf kinase and vascular endothelial growth factor receptor inhibitor, BAY 43-9006, in patients with advanced, refractory solid tumors

PURPOSE

BAY 43-9006, a novel multikinase inhibitor, prevents tumor growth by combining two antitumor activities: inhibition of both tumor cell proliferation and tumor angiogenesis. This phase I, open-label, nonrandomized, noncontrolled, single-arm, dose escalation study was done to determine the maximum tolerated dose (MTD), safety profile, pharmacokinetic variables, effect on biomarkers, and tumor response with BAY 43-9006 in 19 patients with advanced, refractory solid tumors.

EXPERIMENTAL DESIGN

BAY 43-9006 was given orally in repeated cycles of 1-week on/1-week off. The study comprised five dose levels, ranging from 100 mg twice daily (bid) to 800 mg bid. Treatment of each patient continued until unacceptable toxicity, tumor progression, or death.

RESULTS

Rash and hypertension were the dose-limiting toxicities at the 800 mg bid dose requiring study drug discontinuation; therefore, the MTD of BAY 43-9006 in this study was determined to be 600 mg bid. BAY 43-9006 was generally well tolerated, with mild to moderate toxicities. Pharmacokinetic analysis showed early absorption followed by delayed secondary peaks and slow terminal elimination. Stable disease was achieved in five patients: one patient showed reduced tumor activity (positron emission tomography scan) and reduced mitogen-activated protein kinase signaling (lower phospho-ERK); one patient remained on treatment until study end point.

CONCLUSIONS

The results confirm the favorable safety profile of BAY 43-9006 and support the development of this compound for the treatment of solid tumors.

Nuclear localization of long-VEGF is associated with hypoxia and tumor angiogenesis

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor that has a pivotal role in normal and pathological angiogenesis. VEGF has a long 5' untranslated region harboring an open reading frame (ORF) initiated by a CUG codon that is in-frame with the VEGF coding region. The ORF translation leads to the expression of a long isoform termed L-VEGF that is extended by an additional 180 amino acids. In this communication, we provide evidence that L-VEGF is subjected to proteolytic cleavage leading to the detachment of the 180 aa extension from the VEGF moiety. Using immunofluorescence staining, we show that upon hypoxia this 180 aa extension translocates to the nuclei of expressing cells. Accordingly, immunohistochemical staining of both normal and tumor tissue samples demonstrated restricted nuclear localization of the ORF, which was correlated with cytoplasmic localization of VEGF. This suggests that the 180 aa ORF is involved in VEGF-mediated angiogenic processes.

The Expression of Hypoxia-Inducible Factor 1α Is a Favorable Independent Prognostic Factor in Renal Cell Carcinoma

Purpose: Renal cell carcinoma (RCC) is the most common malignancy of the kidney composed of specific tumor types. The sporadic conventional RCCs are, in contrast to the other RCC types, characterized by a high rate of von Hippel-Lindau (VHL) mutations and hypermethylation. The majority of these tumors lack functional VHL protein (pVHL) that leads to increased hypoxia-inducible factor 1α (HIF-1α) expression. The pVHL is the physiologic regulator of the activity of HIF-1α by targeting it to the proteasome for degradation under normoxia. Both pVHL and HIF-1α target other genes that are important for cancer survival and proliferation. Expression of HIF-1α has been linked to poor prognosis in different malignancies, although few studies have been done on the relation between HIF-1α and clinical variables in RCC.

Experimental Design: HIF-1α protein expression was analyzed in tumor tissue from 92 patients with RCC. HIF-1α was quantified by Western blot relative to a positive control.

Results: The HIF-1α protein was expressed as two bands which strongly correlated (r = 0.906, P &lt; 0.001); therefore, they were added and the sum evaluated against clinicopathologic variables. There was no association between HIF-1α and gender, stage, grade, tumor size, or vein invasion. Conventional RCCs had significantly higher HIF-1α expression compared with papillary and chromophobe RCCs and kidney cortex. In conventional RCC, HIF-1α was an independent prognostic factor.

Conclusion: HIF-1α levels varied significantly between the different RCC types. In conventional RCC, HIF-1α was an independent prognostic factor. These data indicate that HIF-1α is involved in tumorogenesis and progression of RCC. Evaluation of other HIF target gene products and correlation to angiogenesis seems warranted.

Vascular endothelial growth factor reduces mural cell coverage of endothelial cells and induces sprouting rather than luminal division in an HT1080 tumour angiogenesis model

Vascular endothelial growth factor (VEGF) plays a central role in tumour angiogenesis. In a mouse intramuscular tumour model using VEGF-transfected HT1080 human fibrosarcoma, we investigated the morphological features and patterns of remodelling in size-matched tumours. Compared with the control tumours (C group), the VEGF-transfected tumours (V group) showed vigorous neovascularization with larger vessels. Fenestrations and disruptions of endothelia were specific to the V group. Three types of vascular remodelling, i.e. sprouting, luminal division and intussusceptive microvascular growth, were present in both groups. Morphometric analyses revealed that mural cell coverage of the endothelial cells was significantly smaller in the V group compared with that in the C group (V group, 28.2 +/- 18.6%; C group, 41.6 +/- 21.1%; P < 0.0001). To determine the prevalence of remodelling patterns, the occurrences of abluminal and luminal processes on endothelial cell surfaces were quantified. Abluminal processes are defined as cytoplasmic protrusions of the abluminal membrane of endothelial cells, which can vary from tiny spurs to solid sprouts of the cell. On the other hand, luminal processes are defined as intraluminal protrusions of the endothelial cell membrane, including various membranous changes from filiform processes to rather thick cytoplasmic bulges. An abluminal process is thought to represent an initial morphological change in sprouting type angiogenesis, and a luminal process to be a sign of implementation of luminal division. The frequency of abluminal processes was significantly higher in the V group than in the C group (V group, 0.243 +/- 0.138/microm; C group, 0.114 +/- 0.101/microm; P < 0.0001). In contrast, the number of luminal processes on the endothelial cells per micrometre was statistically comparable between the groups (V group, 0.285 +/- 0.252/microm; C group, 0.309 +/- 0.236/microm, P = 0.381). These results indicate that sprouting is the main mode of VEGF-induced tumour angiogenesis.

Progression of malignancy in clear cell renal cell carcinomas

Much progress has recently been obtained in the classification and characterization of RCC by using cytogenetic, gene microarray and proteomic techniques. Pivotal for the understanding of the progression of malignancy of clear cell renal cell carcinomas are findings connecting its biology to inactivation of the von Hippel-Lindau tumour suppressor gene product (VHLp), found in most CC-RCCs. Disruption of VHLp function appears to be involved in altered cell cycle control, resistance to hypoxia, hyperangiogenesis and changes in the organization of cytoskeletal and extracellular matrix proteins in RCC. These changes are reflected in the overexpression of the vascular endothelial growth factor (VEGF) and the subunits of hypoxia-inducible factor (HIF), and other angiogenetic and metastasis-promoting factors. Other changes related to progression of malignancy in RCC are the upregulation of proinflammatory cytokines and changes in cell adhesion proteins.