Plasma vascular endothelial but not fibroblast growth factor levels correlate with colorectal liver mestastasis vascularity and volume

Following Chemotherapy: Serum Cytokine (Tumor Necrosis Factor, Interleukin-2, Interleukin-11), Immunoglobulin, Complement, Vascular Endothelial Growth Factor Levels, and the Systemic Symptoms like Capillary Leak Syndrome

Several problems such as myalgia, arthralgia, fever, dyspnea, generalized edema, and pleural effusion can occur in cancer patients following the chemotherapy, especially at the first cycle of the first chemotherapy treatment. Although it is assumed that some cytokines are associated with the development of these symptoms and signs, their pathophysiology has not been discovered completely yet. They are usually mild, but they may rarely progress to the severe stage of "Systemic Capillary Leak Syndrome" with a high mortality rate. The objective of this study was to investigate the association between the serum levels of interleukin-2 (IL-2), interleukin-11 (IL-11), tumor necrosis factor alpha (TNF-α), vascular endothelial growth factor (VEGF), and these symptoms and signs. A total of 44 cancer patients who had neither heart, lung, liver, renal, or thyroid disease were recruited into this study. Their symptoms and signs were examined and questioned before the first cycle of the first chemotherapy treatment and the 24 h after this chemotherapy. All participant's serum samples were taken, and the VEGF, TNF, IL-2, and IL-11 levels were studied. There was no association between the chemotherapeutic drugs, and the symptoms and signs such as edema, dyspnea, coughing, and flu-like symptoms. There was a significant decrease in IL-11 levels in the other treatment group compared with the group receiving paclitaxel, docetaxel, gemcitabine, and vinorelbine in the first day following chemotherapy (P = .006). However, no relation was observed between the symptoms and signs, the response to the chemotherapy, and the serum levels of VEGF, TNF, IL-2, and IL-11. These symptoms and life-threatening syndrome have been a current topic between the clinicians. Although some drugs and mediators are accused, its pathophysiology has not been discovered completely yet. In this study, we could not detect any association between the symptoms, signs, and the cytokine levels following the chemotherapy.

Antiangiogenic therapy for refractory colorectal cancer: current options and future strategies

Even though significant improvements in the treatment of colorectal cancer (CRC) have been made in recent years, survival rates for metastatic colorectal cancer (mCRC) are poor. Effective treatment options for metastatic colorectal cancer remain limited, and new therapeutic strategies are desperately needed. Several tyrosine kinase inhibitors (TKIs) and monoclonal antibodies (mAbs) that target angiogenesis, a critical process for facilitating tumor cell growth, invasion, and metastasis, are either approved or in clinical development for the treatment of mCRC. Many of these agents have shown efficacy in mCRC, both as single agents and in combination with standard chemotherapy regimens. However, there is a need for predictive markers of response to identify those patients most likely to benefit from antiangiogenic therapy, and, to date, no markers of this type have been validated in patients. Additionally, because antiangiogenic agents typically cause cytostatic as opposed to cytotoxic antitumor effects, it is important to determine the best strategies for evaluating therapeutic response in mCRC to ensure maximum clinical benefit. In this review, we summarize the efficacy and tolerability of approved and investigational antiangiogenic agents for the treatment of mCRC. We also discuss potential markers of response to antiangiogenic agents and how these markers, along with appropriate endpoint selection, can improve clinical trial design.

What could Nintedanib (BIBF 1120), a triple inhibitor of VEGFR, PDGFR, and FGFR, add to the current treatment options for patients with metastatic colorectal cancer?

Increasing knowledge of the pro-angiogenic processes involved in the progression of metastatic colorectal cancer (mCRC) has resulted in the clinical development of several anti-angiogenic agents, with bevacizumab currently being the only approved agent for mCRC. Nintedanib (BIBF 1120) has been shown to block the vascular endothelial growth factor receptor (VEGFR), the platelet-derived growth factor receptor (PDGFR), and the fibroblast growth factor receptor (FGFR). By targeting FGFR signaling, nintedanib may overcome resistance to previous anti-VEGF treatments, and may represent a better approach in patients with high basal levels of circulating FGFs. In this article, the angiogenic mechanisms implicated in mCRC are reviewed (focusing on the signaling pathways activated by VEGFR, PDGFR, and FGFR), along with the clinical data for nintedanib in the context of other anti-angiogenic tyrosine kinase inhibitors under clinical development for mCRC. Biomarkers that could predict response to nintedanib are also discussed.

Vascular endothelial growth factor in the circulation in cancer patients may not be a relevant biomarker

BACKGROUND

Levels of circulating vascular endothelial growth factor (VEGF) have widely been used as biomarker for angiogenic activity in cancer. For this purpose, non-standardized measurements in plasma and serum were used, without correction for artificial VEGF release by platelets activated ex vivo. We hypothesize that "true" circulating (c)VEGF levels in most cancer patients are low and unrelated to cancer load or tumour angiogenesis.

METHODOLOGY

We determined VEGF levels in PECT, a medium that contains platelet activation inhibitors, in citrate plasma, and in isolated platelets in 16 healthy subjects, 18 patients with metastatic non-renal cancer (non-RCC) and 12 patients with renal cell carcinoma (RCC). In non-RCC patients, circulating plasma VEGF levels were low and similar to VEGF levels in controls if platelet activation was minimized during the harvest procedure by PECT medium. In citrate plasma, VEGF levels were elevated in non-RCC patients, but this could be explained by a combination of increased platelet activation during blood harvesting, and by a two-fold increase in VEGF content of individual platelets (controls: 3.4 IU/10(6), non-RCC: 6.2 IU/10(6) platelets, p = 0.001). In contrast, cVEGF levels in RCC patients were elevated (PECT plasma: 64 pg/ml vs. 21 pg/ml, RCC vs. non-RCC, p<0.0001), and not related to platelet VEGF concentration.

CONCLUSIONS

Our findings suggest that "true" freely cVEGF levels are not elevated in the majority of cancer patients. Previously reported elevated plasma VEGF levels in cancer appear to be due to artificial release from activated platelets, which in cancer have an increased VEGF content, during the blood harvest procedure. Only in patients with RCC, which is characterized by excessive VEGF production due to a specific genetic defect, were cVEGF levels elevated. This observation may be related to limited and selective success of anti-VEGF agents, such as bevacizumab and sorafenib, as monotherapy in RCC compared to other forms of cancer.

High levels of circulating VEGFR2+ Bone marrow-derived progenitor cells correlate with metastatic disease in patients with pediatric solid malignancies

PURPOSE

Pediatric solid malignancies display important angiogenic potential, and blocking tumor angiogenesis represents a new therapeutic approach for these patients. Recent studies have evidenced rare circulating cells with endothelial features contributing to tumor neovascularization and have shown the pivotal role of bone marrow-derived (BMD) progenitor cells in metastatic disease progression. We measured these cells in patients with pediatric solid malignancies as a prerequisite to clinical trials with antiangiogenic therapy.

PATIENTS AND METHODS

Peripheral blood was drawn from 45 patients with localized (n = 23) or metastatic (n = 22) disease, and 20 healthy subjects. Subsets of circulating vascular endothelial growth factor receptor (VEGFR)2+-BMD progenitor cells, defined as CD45-CD34+VEGFR2(KDR)+7AAD- and CD45(dim)CD34+VEGFR2+7AAD- events, were measured in progenitor-enriched fractions by flow cytometry. Mature circulating endothelial cells (CEC) were measured in whole blood as CD31+CD146+CD45-7AAD- viable events. Data were correlated with VEGF and sVEGFR2 plasma levels.

RESULTS

The CD45-CD34+VEGFR2(KDR)+7AAD- subset represented <0.003% of circulating BMD progenitor cells (< or =0.05 cells/mL). However, the median level (range) of the CD45(dim)CD34+VEGFR2+7AAD- subset was higher in patients compared with healthy subjects, 1.5% (0%-10.3%) versus 0.3% (0%-1.6%) of circulating BMD progenitors (P < 0.0001), and differed significantly between patients with localized and metastatic disease, 0.7% (0%-8.6%) versus 2.9% (0.6%-10.3%) of circulating BMD progenitors (P < 0.001). Median CEC value was 7 cells/mL (0-152 cells/mL) and similar in all groups. Unlike VEGFR2+-BMD progenitors, neither CECs, VEGF, or sVEGFR2 plasma levels correlated with disease status.

CONCLUSION

High levels of circulating VEGFR2+-BMD progenitor cells correlated with metastatic disease. Our study provides novel insights for angiogenesis mechanisms in pediatric solid malignancies for which antiangiogenic targeting of VEGFR2+-BMD progenitors could be of interest.

Clinical significance of plasma and serum vascular endothelial growth factor in asthma

BACKGROUND

Vascular endothelial growth factor (VEGF) is a mediator of airway inflammation and remodeling in asthma.

PURPOSE

We investigated whether VEGF levels are elevated in plasma and serum obtained from patients with asthma and evaluated whether levels of plasma VEGF correlated with those of serum VEGF.

METHODS

We measured levels of plasma and serum VEGF in patients with stable asthma or with acute asthma and examined the correlation between plasma and serum VEGF concentration with initial forced expiratory volume in 1 second (FEV(1)).

RESULTS

We found that levels of VEGF in plasma or in serum were significantly increased in stable asthmatic patients and even higher in acute asthmatic patients compared with the levels in healthy control subjects. The levels of serum VEGF correlated significantly with those of plasma VEGF. Additionally, the circulating VEGF levels were significantly inversely correlated with the percent predicted FEV(1).

CONCLUSION

These results suggest that the overproduction of VEGF is implicated in asthma exacerbation and that measurement of either plasma or serum VEGF level can be a valid index in asthmatic patients. Therefore, the changes in the VEGF levels in peripheral blood of asthmatic patients can be used as a measure for progression of asthma during treatment.

Expression and significance of NF-κB and VEGF in gastric carcinoma

AIM: To investigate the expression and clinical significance of nuclear factor-kappa B (NF-κB) and vascular endothelial growth factor (VEGF) in gastric carcinoma.

METHODS: Sixty-eight patients with gastric carcinoma were selected as experimental group, and their corresponding noncarcinoma tissues were selected as control group, and 20 normal healthy gastric tissue samples were taken as normal control group. Immunohistochemical method (SABC) was used to test the NF-κB and VEGF protein. And the clinical pathological data were statistically analyzed.

RESULTS: NF-κB and VEGF were not expressed in normal gastric tissues, but were positively expressed in control group and in study group with a significant difference detected (63.2% vs 2.9%, 76.5% vs 14.7%, both P = 0.000). Expression of NF-κB and VEGF were not correlated with the gender, age and histological type in gastric carcinoma. While the expression of NF-κB and VEGF in gastric carcinoma with TNM stage (Ⅲ + Ⅳ), lymph node metastasis, serous membrane involved, and distant metastasis were significantly higher than those of TNM stage (Ⅰ + Ⅱ), without lymph node metastasis, or without serous membrane involved, or without distant metastasis (P < 0.05), respectively. There was significantly positive correlation between NF-κB and VEGF in gastric carcinoma (r = 0.512, P = 0.000).

CONCLUSION: NF-κB and VEGF are both significantly expressed in gastric carcinoma and there is a positive correlation between them. And the possible mechanism is that NF-κB up-regulates VEGF, hence promotes the development of gastric carcinoma.

Post-collection, pre-measurement variables affecting VEGF levels in urine biospecimens

Angiogenesis, the development and recruitment of new blood vessels, plays an important role in tumour growth and metastasis.Vascular endothelial growth factor (VEGF) is an important stimulator of angiogenesis.Circulating and urinary VEGF levels have been suggested as clinically useful predictors of tumour behaviour, and investigations into these associations are ongoing.Despite recent interest in measuring VEGF levels in patients, little is known about the factors that influence VEGF levels in biospecimens. To begin to address this question, urine samples were collected from patients with solid tumours undergoing radiotherapy and healthy volunteers.Four factors were examined for their effects on VEGF concentrations as measured by chemiluminescent immunoassay: time from sample collection to freezing, number of specimen freeze–thaw cycles, specimen storage tube type and the inclusion or exclusion of urinary sediment. The results of this study indicate that time to freeze up to 4 hrs, number of freeze–thaw cycles between one and five, and different types of polypropylene tubes did not have statistically significant effects on measured urinary VEGF levels. Urinary sediment had higher VEGF levels than supernatant in five of six samples from healthy patients.It is not clear whether there is an active agent in the sediment causing this increase or if the sediment particles themselves are affecting the accuracy of the assay.Therefore, we recommend centrifuging urine, isolating the supernatant, and freezing the sample in polypropylene microcentrifuge tubes or cryogenic vials within 4 hrs of collection.In addition, we recommend the use of samples within five freeze–thaw cycles.

Levels of VEGF-A mRNA in plasma from patients with colorectal carcinoma as possible surrogate marker of angiogenesis

PURPOSE

The regulator of angiogenesis most extensively studied is VEGF. VEGF mRNA in plasma from patients with colorectal cancer was analyzed as a possible surrogate marker of tumor angiogenesis.

METHODS

VEGF mRNA was measured by quantitative PCR in plasma, tumors and circulating tumor cells from colorectal cancer patients. Circulating VEGF protein was analyzed by ELISA. Microvessel density was determined.

RESULTS

Levels of VEGF mRNA and protein in plasma were higher in patients than in controls. VEGF mRNA was overexpressed in tumors with respect to normal tissues. Levels of VEGF protein were associated with VEGF mRNA in plasma, but no associations with tumor samples were found. A trend to statistical significance was shown between high VEGF mRNA and vascular invasion. MVD was not related to VEGF mRNA in plasma.

CONCLUSIONS

Thus, VEGF mRNA could be a marker similar to VEGF protein in plasma.

Development of time-resolved immunofluorometric assays for vascular endothelial growth factor and application on plasma of patients with gastric tumours

A highly sensitive and accurate time-resolved immunofluorometric assay (TR-IFMA) has been developed, for the first time, to measure plasma vascular endothelial growth factor (VEGF) in patients with gastric tumours. A monoclonal anti-hVEGF antibody and a biotinylated anti-hVEGF antibody were used to develop a non-competitive 'sandwich'-type assay. Fluorescence can be measured by a time-resolved fluorometer after binding of europium (Eu)(3+)-labelled streptavidin to the biotinylated immunoglobulin. Plasma VEGF concentrations were measured by TR-IFMA in 92 healthy controls, in 36 benign stomach disease patients and in 92 gastric cancer patients before surgery. The association between plasma VEGF levels and clinicopathological features was evaluated. A standard curve for VEGF TR-IFMA has been developed with good sensitivity (0.37 pg/ml). Accuracy studies, specificity, parallelism and precision data were determined and all were found to be satisfactory. The validity of the VEGF assay was confirmed by the good correlation between the results obtained by TR-IFMA and commercial enzyme-linked immunosorbent assay (ELISA) (ELISA result = 1.862 + 0.953 (TR-IFMA result), r = 0.944]. The plasma levels of VEGF are higher in gastric cancer patients than in healthy controls. VEGF levels were associated significantly with the presence of distant metastases, as well as invasion depth of the tumour and tumour stage, but not with tumour location, tumour histology, differentiation or the presence of lymph node metastases. At the cut-off of 217.79 pg/ml, the diagnostic sensitivity, specificity and accuracy of the TR-IFMA were 40.2%, 93.7% and 69.9%, respectively. A highly sensitive and reliable TR-IFMA for VEGF has been developed. The determination of plasma VEGF levels may be clinically useful.

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.

Prognostic value of serum angiogenic activity in colorectal cancer patients

Angiogenesis, resulting from an imbalance between angiogenic activator factors and inhibitors, is required for tumour growth and metastasis. The determination of the circulating concentration of all angiogenic factors (activators and inhibitors) is not feasible at present. We have evaluated diagnostic and prognostic values of the measurement of serum angiogenic activity in colorectal carcinoma (CRC) patients. Serum proliferative activity (PA) on human umbilical vein endothelial cells (HUVEC) in vitro, and serum vascular endothelial growth factor (VEGF) levels were determined by ELISA in 53 patients with primary CRC, 16 subjects with non-neoplastic gastrointestinal disease (SC) and 34 healthy individuals. Data were compared with clinical outcome of the patients. Although serum from CRC patients significantly increased the PA of HUVEC, compared to culture control (HUVEC in medium + 10% foetal bovine serum (FBS); P < 0.001); our results indicate that serum PA in CRC patients was similar to that of SC or healthy individuals. There was no correlation between serum PA and circulating VEGF concentrations. Surgery produced a decrease of PA at 8 hrs after tumour resection in CRC patients compared to pre-surgery values (186 +/- 47 versus 213 +/- 41, P < 0.001). However, an increase in serum VEGF values was observed after surgery (280 [176-450] versus 251 [160-357] pg/ml, P = 0.004). Patients with lower PA values after surgery showed a worse outcome that those with higher PA values. Therefore, this study does not support a diagnostic value for serum angiogenic activity measured by proliferative activity on HUVEC but suggests it could have a prognostic value in CRC patients.

A list of candidate cancer biomarkers for targeted proteomics

We have compiled from literature and other sources a list of 1261 proteins believed to be differentially expressed in human cancer. These proteins, only some of which have been detected in plasma to date, represent a population of candidate plasma biomarkers that could be useful in early cancer detection and monitoring given sufficiently sensitive specific assays. We have begun to prioritize these markers for future validation by frequency of literature citations, both total and as a function of time. The candidates include proteins involved in oncogenesis, angiogenesis, development, differentiation, proliferation, apoptosis, hematopoiesis, immune and hormonal responses, cell signaling, nucleotide function, hydrolysis, cellular homing, cell cycle and structure, the acute phase response and hormonal control. Many have been detected in studies of tissue or nuclear components; nevertheless we hypothesize that most if not all should be present in plasma at some level. Of the 1261 candidates only 9 have been approved as "tumor associated antigens" by the FDA. We propose that systematic collection and large-scale validation of candidate biomarkers would fill the gap currently existing between basic research and clinical use of advanced diagnostics.

A list of candidate cancer biomarkers for targeted proteomics

We have compiled from literature and other sources a list of 1261 proteins believed to be differentially expressed in human cancer. These proteins, only some of which have been detected in plasma to date, represent a population of candidate plasma biomarkers that could be useful in early cancer detection and monitoring given sufficiently sensitive specific assays. We have begun to prioritize these markers for future validation by frequency of literature citations, both total and as a function of time. The candidates include proteins involved in oncogenesis, angiogenesis, development, differentiation, proliferation, apoptosis, hematopoiesis, immune and hormonal responses, cell signaling, nucleotide function, hydrolysis, cellular homing, cell cycle and structure, the acute phase response and hormonal control. Many have been detected in studies of tissue or nuclear components; nevertheless we hypothesize that most if not all should be present in plasma at some level. Of the 1261 candidates only 9 have been approved as "tumor associated antigens" by the FDA. We propose that systematic collection and large-scale validation of candidate biomarkers would fill the gap currently existing between basic research and clinical use of advanced diagnostics.

Comparison of angiogenic factor levels in tumor drainage and peripheral venous blood from colorectal cancer patients

BACKGROUND

The main objective of this study was to determine whether there was a correlation in the levels of various angiogenesis-related factors between the tumor drainage and peripheral venous blood and whether appraisal of angiogenic factor levels in the tumor drainage venous blood could provide better prognostic information for patients with colorectal cancer than assessment of the peripheral venous blood.

METHODS

Plasma levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor, and endostatin were measured and compared in both tumor drainage and peripheral venous blood from 52 patients with colorectal cancer. Plasma levels of angiogenesis-related factors were also correlated with tumor stage and clinical outcomes.

RESULTS

The plasma endostatin level was significantly higher in peripheral blood than in tumor drainage venous blood (P < .001). The plasma VEGF level was significantly correlated with plasma endostatin levels (P = .028 in tumor drainage venous blood and P = .002 in peripheral venous blood). In both tumor drainage and peripheral venous blood, the VEGF level (but not the basic fibroblast growth factor or endostatin level) was significantly correlated with tumor stage and disease recurrence. However, in multivariate analysis, only plasma VEGF level in tumor drainage venous blood remained an independent predictor of disease recurrence.

CONCLUSIONS

The plasma VEGF level in tumor drainage venous blood provided better prognostic information than that in peripheral venous blood. The plasma endostatin level was paradoxically significantly higher in peripheral than in tumor drainage blood, and this strongly suggests additional sources of endostatin in peripheral blood.

Interaction between stromal fibroblasts and colorectal cancer cells in the expression of vascular endothelial growth factor

BACKGROUND

Vascular endothelial growth factor (VEGF), a potent angiogenic factor, has been implicated in metastasis of colorectal cancer (CRC). The present study aimed to clarify whether cancer-stromal interaction induces the production of VEGF.

MATERIALS AND METHODS

Human colonic fibroblasts (CCD-18Co) and CRC (SW480, SW620) cells were analyzed in this study. The cell cycle of colonic fibroblasts during co-culture was analyzed by flow cytometry. VEGF and TGF-beta1 released into the conditioned media in co-culture models were measured. Northern blot with human specific VEGF probe was performed to identify the expression of VEGF in this model.

RESULTS

Co-culture of colonic fibroblasts with CRC cells increased the viability of fibroblasts during co-culture. Cell cycle analysis revealed that most of the fibroblasts co-cultured with CRC cells were arrested at G1 phase and few cells were in sub-G1 phase that indicates apoptosis. Although VEGF protein was detected in the culture media of all of the monocultures, co-cultivation of CRC with fibroblasts resulted in synergistic increase of VEGF production compared with monocultures. However TGF-beta1 protein was not detected in any conditioned medium. VEGF mRNA was detected in both CRC and fibroblasts. Under co-culture condition, an abundance of VEGF mRNA expression was noted in fibroblasts relative to CRC cells.

CONCLUSIONS

The present study suggests that CRC manipulates the host stroma to suppress apoptosis and up-regulate VEGF production.

Preoperative plasma vascular endothelial growth factor but not nitrite is a useful complementary tumor marker in patients with colorectal cancer

PURPOSE

Vascular endothelial growth factor and nitric oxide are both related to tumor progression. This study was designed to measure preoperative plasma vascular endothelial growth factor and nitrite levels in patients with colorectal cancer to evaluate their clinical applications as tumor markers.

METHODS

In total, 279 patients with primary colorectal cancer and 20 patients with hemorrhoids (as a control) were included in this study. Plasma vascular endothelial growth factor was measured by quantitative, solid-phase, enzyme-linked immunosorbent assay (R&D Systems), whereas nitrite was measured by a high-performance liquid chromatographic method.

RESULTS

The vascular endothelial growth factor (mean, 220.6 pg/ml, P < 0.005) and nitrite (mean, 29.4 microM, P = 0.043) levels of patients with cancer were significantly higher than those of controls (mean vascular endothelial growth factor, 67 pg/ml; mean nitrite, 23 microM). Preoperative plasma vascular endothelial growth factor levels were positively correlated with tumor stage, T class, M class, and tumor size (Spearman correlation, P < 0.01), but were not associated with gender, N class, tumor location, histology type, or grade. There were no statistical differences in nitrite levels among different groups of patients with cancer. Higher vascular endothelial growth factor levels also were correlated with leukocytosis, elevated carcinoembryonic antigen, and a higher platelet count. The positive rates of vascular endothelial growth factor elevation (>148.6 pg/ml) compared with carcinoembryonic antigen elevation were 36.9 to 14.6 percent in Stage I, 60.9 to 33 percent in Stage II, 62.9 to 48.7 percent in Stage III, and 86 to 70.2 percent in Stage IV, respectively. The overall positive rate of vascular endothelial growth factor elevation also was higher than that of carcinoembryonic antigen elevation (63 percent for vascular endothelial growth factor vs. 42.5 percent for carcinoembryonic antigen, P = 0.016). More than one-half of the patients without carcinoembryonic antigen elevation still had elevated vascular endothelial growth factor levels. The combined assessment using vascular endothelial growth factor and carcinoembryonic antigen was superior to individual assessment using vascular endothelial growth factor or carcinoembryonic antigen. In node-negative tumor, the patients with vascular endothelial growth factor elevation had worse disease-free survival than those without vascular endothelial growth factor elevation (P = 0.0367). There was no association of vascular endothelial growth factor elevation with survival in patients with node-positive tumor.

CONCLUSIONS

Plasma vascular endothelial growth factor is a useful complementary tumor marker; however, synchronous measurement of white blood cells, platelets, and carcinoembryonic antigen is suggested in the clinical application of vascular endothelial growth factor to colorectal cancer.

Profile of plasma angiogenic factors before and after hepatectomy for colorectal cancer liver metastases

BACKGROUND

Circulating angiogenic factors in patients with colorectal cancer liver metastases may promote tumor growth and contribute to liver regeneration after partial hepatectomy.

METHODS

We analyzed blood samples from 26 patients with colorectal cancer liver metastases before and after liver resection and used samples from 20 healthy controls as a reference. Plasma levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and hepatocyte growth factor (HGF) were measured, and levels were correlated with recurrence.

RESULTS

The median preoperative levels of all four factors were significantly higher and more variable in colorectal cancer liver metastasis patients than in controls. HGF and bFGF levels increased significantly 3 days and 1 month after hepatectomy, respectively, and returned to near preoperative levels at 3 months. Postoperative VEGF and EGF levels remained relatively stably increased over 3 months. After a median follow-up of 19 months, 10 patients (42%) experienced recurrence. Higher preoperative VEGF and HGF levels correlated with subsequent recurrence (P = .018 and .021, respectively), and a preoperative adjusted total value of all four factors accurately identified patients at low, moderate, and high risk of recurrence (P = .034). Patients who experienced disease recurrence also had relatively higher bFGF levels 3 months after operation (P = .035).

CONCLUSIONS

Plasma angiogenic factors are increased in patients with colorectal cancer liver metastases and remain increased at least 3 months after partial hepatectomy. Measurement of certain factors before and after hepatic resection can predict recurrence. Targeted biological agents may counteract the tumor-promoting effects of these circulating factors on subclinical disease.

Expression of angiogenic VEGF-A (soluble isoforms 121, 165) and lymphangiogenic VEGF-C in colorectal cancers with micro-satellite instability

BACKGROUND AND OBJECTIVES

Colorectal cancers (CRC) with high-level micro-satellite instability (MSI-H) show reduced metastatic potential and better prognosis compared to stage-matched stable (MSS) cancers. Angiogenesis/lymphangiogenesis, central to tumour growth and spread, is mediated by vascular endothelial growth factor (VEGF) cytokines, but little is known of their relationship to MSI.

METHODS

In this study, 67 sporadic CRC with identified MSI status, and 8 samples of normal colon were analysed for VEGF-A soluble isoforms (VEGF-121/VEGF-165) and VEGF-C gene transcription (by RT-PCR and scanning densitometry), and blood vessel density (BVD; measuring angiogenesis) and VEGF-C protein expression (measuring lymphangiogenesis).

RESULTS

Compared to normal colon, VEGF-165 transcription was reduced (P < 0.05), but VEGF-121 transcription was higher in MSS (P < 0.06) and MSI-L (P < 0.01) cancers (but similar in MSI-H). VEGF-165 transcription was unrelated to MSI, but VEGF-121 transcription was elevated in MSI-L (P < 0.06). There was a weak inverse correlation with VEGF-121 transcription and Dukes stage (P < 0.09), and with BVD and MSI (P < 0.09). With a singular di-nucleotide loci mutation (MSI-L), VEGF-121 (P < 0.03) and VEGF-C (P < 0.04) transcription was elevated.

CONCLUSIONS

MSI-H cancers have reduced angiogenic/lymphangiogenic potential, and transcription of VEGF-121 may be important in early growth and spread of CRC. Elevated VEGF-121 and VEGF-C transcription with singular di-nucleotide mutations may aid in the identification of distinct MSI-L cancers.

Impact of vascular endothelial growth factor-A expression, thrombospondin-2 expression, and microvessel density on the treatment effect of bevacizumab in metastatic colorectal cancer

PURPOSE

Bevacizumab is a monoclonal antibody to vascular endothelial growth factor-A (VEGF). In the pivotal trial in metastatic colorectal cancer (mCRC), addition of bevacizumab to first-line irinotecan, fluorouracil, and leucovorin (IFL) significantly prolonged median survival. The aim of these retrospective subset analyses was to evaluate VEGF, thrombospondin-2 (THBS-2), and microvessel density (MVD) as prognostic factors and/or predictors of benefit from bevacizumab.

PATIENTS AND METHODS

In the pivotal trial, 813 patients with untreated mCRC were randomly assigned to receive IFL plus bevacizumab or placebo. Of 312 tissue samples collected (285 primaries, 27 metastases), outcome data were available for 278 (153 bevacizumab, 125 placebo). Epithelial and stromal VEGF expression were assessed by in situ hybridization (ISH) and immunohistochemistry on tissue microarrays and whole sections. Stromal THBS-2 expression was examined by ISH on tissue microarrays. MVD was quantified by Chalkley count. Overall survival was associated with these variables in retrospective subset analyses.

RESULTS

In all subgroups, estimated hazard ratios (HRs) for risk of death were < 1 for bevacizumab-treated patients regardless of the level of VEGF or THBS-2 expression or MVD. Patients with a high THBS-2 score showed a nonsignificant improvement in survival following bevacizumab treatment (HR = 0.11; 95% CI, 0.02 to 0.51) compared to patients with a low score (HR = 0.65; 95% CI, 0.41 to 1.02); interaction analysis P = .22. VEGF or THBS-2 expression and MVD were not significant prognostic factors.

CONCLUSION

These exploratory analyses suggest that in patients with mCRC addition of bevacizumab to IFL improves survival regardless of the level of VEGF or THBS-2 expression, or MVD.

The role of cystatin C and the angiogenic cytokines VEGF and bFGF in patients with esophageal carcinoma

Angiogenesis is the formation of new blood vessels out of the existing vascular bed. Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are potent circulating angiogenic factors, whereas cystatin C is one of the most important extracellular inhibitors of several cysteine proteinases. Because proteases degrade interstitial connective tissue and basement membranes during tumor growth and metastasis, an association between cystatin C and the angiogenic factors seems plausible. The primary aim of the present study was to investigate if such a correlation exists between these serum markers. The secondary aim was to determine the prognostic value of these circulating cytokines and cystatin C, collected prior to therapy, in patients with esophageal carcinoma.A total of 42 patients with esophageal carcinoma donated serum samples prior to therapy. VEGF and bFGF were correlated to platelet and leukocyte counts and VEGF was correlated to tumor volume (p = 0.04), whereas bFGF was not (p = 0.08). VEGF was significantly correlated with cystatin C (p = 0.027). Survival analysis showed that VEGF regarded as a continuous variable was associated with a significantly poorer survival in the univariate analysis (p = 0.023); however, this was not found for bFGF (p = 0.46). Neither of the angiogenic factors were associated with survival in the multivariate analysis. In the univariate analysis, cystatin c was correlated with survival (p = 0.01), but this was not found in the multivariate analysis (p = 0.28). In conclusion, VEGF was correlated with cystatin C, possible explanations being discussed in the present article. Results of the present study indicate that use of the angiogenic factors as prognostic factors, prior to therapy in patients with esophageal carcinoma, appears limited.

Clinical significance of serum cytokine measurements in untreated colorectal cancer patients: soluble tumor necrosis factor receptor type I--an independent prognostic factor

The aim of this study was to exploit the potential clinical use of circulating cytokine measurements in colorectal cancer (CRC) patients. The levels of cytokines and cytokine receptors were assessed by ELISA in the sera of 50 healthy volunteers and 157 patients with previously untreated CRC and then related to clinicopathological features and prognosis. All tumors were verified histologically as colorectal adenocarcinomas and staged according to TNM classification. The levels of circulating interleukin (IL)-6, IL-8, macrophage colony-stimulating factor (M-CSF) and interleukin 1 receptor antagonist (IL-1ra) significantly increased with the clinical stage of CRC, and the levels of IL-6, soluble tumor necrosis factor (sTNF) receptor type I (RI), soluble interleukin 2 receptor alpha and TNFalpha with tumor grade, while IL-6, IL-8, M-CSF, IL-1ra and sTNF RI levels significantly rose with bowel wall invasion. None of the cytokine or soluble cytokine receptor levels were influenced by age, gender and colon versus rectum localization. sTNF RI, IL-8, IL-6 and vascular endothelial growth factor measurements demonstrated the highest diagnostic sensitivity. sTNF RI was found elevated in the greatest percentage of all CRC patients, in the greatest proportion of stage I patients and presented the best diagnostic sensitivity. In addition, the sTNF RI level strongly correlated with tumor grade and invasion and proved to be an independent prognostic factor.

Hepatic tumor growth: target for angiogenesis inhibition?

Pathologic angiogenesis induced by a tumor is essential for its survival. The promise of tumor inhibition by targeting angiogenesis over the past several years has translated into numerous ongoing clinical trials. Recently, in a phase III trial involving patients with metastatic colorectal cancer, Bevacizumab (Genentech, Inc, San Francisco, CA), a recombinant humanized monoclonal antibody against vascular endothelial growth factor used in conjunction with standard chemotherapy was shown to increase survival, progression-free survival, response rate, and duration of response compared to chemotherapy alone. Thus far, duration of the increased response remains less than 6 months. The majority of deaths in patients with colorectal cancer are related to hepatic metastases. It is hoped that novel approaches directed at the complex interactions between tumor and microenvironment in the angiogenic process will strengthen the therapeutic armamentarium against hepatic malignancies.

Role of serum vascular endothelial growth factor in the prediction of angiogenesis and prognosis for non-small cell lung cancer

Although vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP)-9 are involved in angiogenesis of various cancers, clinical utility of preoperative serum concentration of these molecules in non-small cell lung cancer (NSCLC) has not yet been elucidated. In this study, we determined the concentration of VEGF, MMP-9 and various other tumor markers in serum prior to surgery and evaluated the results compared with intratumoral vasculature to isolate a valuable marker in determining the prediction of angiogenesis in NSCLC. Among these molecules and serum tumor markers, circulating serum VEGF was identified to markedly correlate with microvessel density (MVD) of the resected tumor specimens. Moreover, overall survival of patients with low VEGF levels (< or =326 ng/ml) was significantly greater than that of patients with high VEGF levels (>326 ng/ml), while patients with low MMP-9 levels (< or =189 ng/ml) and those with high MMP-9 levels (>189 ng/ml) revealed similar overall survival. Conclusively, preoperative concentration of serum VEGF may be the most valuable marker in the prediction of intratumoral angiogenesis and prognosis of patients with NSCLC.

Preliminary study of plasma vascular endothelial growth factor (VEGF) during low- and high-dose radiation therapy of dogs with spontaneous tumors

High plasma vascular endothelial growth factor (VEGF) concentrations are associated with radiation resistance and poor prognosis. After an exposure to ionizing radiation in cell culture an early phase and a late phase of increased VEGF have been documented. The activation was dependent on the radiation dose. Therefore, the purpose of this study was to measure baseline plasma VEGF and changes in VEGF over the course of fractionated radiation therapy in dogs with spontaneous tumors. Dogs with tumors had a significantly higher pretreatment plasma VEGF than did dogs without tumors. Immediately after irradiation no increased plasma VEGF was observed. Over the course of radiation therapy there was an increased plasma VEGF in dogs treated with low doses per fraction/high total dose, whereas plasma VEGF remained stable in dogs irradiated with high doses per fraction/low total dose. The regulatory mechanisms are very complex, and therefore the value of plasma VEGF measurements as an indirect marker of angiogenesis induced by radiotherapy is limited.

Increased serum transforming growth factor-beta1 in human colorectal cancer correlates with reduced circulating dendritic cells and increased colonic Langerhans cell infiltration

Cancer-related cytokines may interfere with the differentiation and migration of dendritic cells (DCs) and with the associated up-regulation of co-stimulatory molecules in vitro. We determined whether cytokines affected the distribution and activation of DCs in patients with colorectal cancer by measuring the levels of serum cytokines [transforming growth factor (TGF)-beta1 and vascular endothelial growth factor (VEGF)], DC numbers and phenotype from peripheral blood and mesenteric lymph nodes draining the cancer, and the infiltration of DCs into colorectal cancer. A significant increase in the serum level of TGF-beta1 correlated with a significant reduction in the level of circulating DCs in cancer patients that was associated with an increased infiltration of Langerhans cells into colorectal mucosa. The prevalence but not intensity of co-stimulatory molecule expression in circulating and mesenteric lymph node DCs was reduced in patients with colorectal cancer compared to patients with inflammatory bowel conditions. There was no correlation between co-stimulatory molecule expression and serum TGF-beta1. Thus the circulating DC depletion in colorectal cancer could be explained by a TGF-beta1-related DC redistribution from the circulation into the colorectal cancer and adjacent mucosa where DC levels were increased. There was an impairment of DC activation within colorectal cancer that was not related to serum level of cytokines.

Evaluation of the levels of bFGF, VEGF, sICAM-1, and sVCAM-1 in serum of patients with thyroid cancer

Tumour growth and development depend on a complex cascade of angiogenic factors. The aim of the study is evaluation of the level of growth factors VEGF and bFGF, and adhesion molecules sICAM-1, sVCAM-1 in the serum of patients with papillary thyroid cancer. The study comprised 35 patients aged 21-68 years (mean age 46+/-14) who had papillary thyroid cancer diagnosed on the basis of thin needle aspiration biopsy, and were qualified for operative treatment. This group comprised 28 women and seven men. The control group was 26 healthy individuals. Serum concentrations of bFGF, VEGF, sICAM-1, and sVCAM-1 were evaluated by the enzyme-linked immunosorbent assay (ELISA) method. We have observed significantly higher mean concentrations of bFGF, VEGF, and sICAM-1 in the serum of patients with thyroid cancer compared with the control group. There was no significant difference between the sVCAM-1 concentrations of the thyroid cancer group and the control group.

Clinical significance of angiogenesis in gastrointestinal cancers: a target for novel prognostic and therapeutic approaches

OBJECTIVE

To review the current data on the prognostic and therapeutic implications of tumor angiogenesis in gastrointestinal cancers.

SUMMARY BACKGROUND DATA

Numerous studies have evaluated the prognostic value of tumor angiogenesis and the potential role of antiangiogenic therapy in various gastrointestinal cancers.

METHODS

A Medline literature search was conducted using "angiogenesis" or the names of various angiogenic factors in combination with the names of gastrointestinal cancers as the key words.

RESULTS

Several studies have demonstrated a significant prognostic impact of tumor microvessel density and tumor expression of angiogenic factors, in particular vascular endothelial growth factor (VEGF), in various gastrointestinal cancers. A few studies have suggested that circulating VEGF might be a useful prognostic marker. However, results were not consistent across all studies and were limited by the retrospective nature of most studies. Antiangiogenic therapy has been shown to be effective against all common gastrointestinal cancers in preclinical studies, but currently there are few clinical data with regard to antiangiogenic therapy in gastrointestinal cancers.

CONCLUSIONS

There is mounting evidence to suggest that assessment of tumor angiogenesis might provide a novel approach of prognostication in patients with gastrointestinal cancers. However, current results from retrospective studies need to be validated by prospective studies. Antiangiogenic therapy is a promising strategy of cancer treatment that might be particularly useful in combination therapy for unresectable cancers or as an adjuvant therapy for resectable tumors.

The role of circulating IL-8 and VEGF protein in the progression of gastric cancer

Both vascular endothelial growth factor (VEGF) and interleukin 8 (IL-8) play an important role in the progression of gastric cancer (GC). In this study, we investigated whether circulating levels of VEGF or IL-8 in drainage veins of GC patients were correlated with any clinicopathological factors. Thirty-seven patients with primary GC who underwent gastrectomy at our department between 1999 and 2002 were analyzed. Blood samples were drawn from a peripheral vein just before surgery and from a drainage vein immediately after laparotomy. Plasma VEGF levels were significantly higher than those in 10 healthy controls. There was no correlation between VEGF levels in drainage veins and any clinicopathological variable, whereas there was a significant relationship in the case of VEGF levels in peripheral veins; the levels were higher in patients with venous invasion. We found a significant relationship between IL-8 levels in drainage veins and both tumor size and lymph node metastasis, whereas no significant relationship between IL-8 levels in peripheral veins and any variable was found. There was no correlation between VEGF and IL-8 levels in drainage veins. Large tumors, deeply invasive tumors, lymph node involvement, venous invasion and high IL-8 levels in drainage veins were all significantly associated with shorter disease-free survival, although multivariate analysis revealed that lymph node involvement was the only independent prognostic factor. In conclusion, the measurement of IL-8 levels in drainage veins of GC patients may reflect production mainly by the primary lesion and is valuable as an indicator of risk for recurrent disease.

Clinical significance of angiogenesis in gastrointestinal cancers: a target for novel prognostic and therapeutic approaches

OBJECTIVE

To review the current data on the prognostic and therapeutic implications of tumor angiogenesis in gastrointestinal cancers.

SUMMARY BACKGROUND DATA

Numerous studies have evaluated the prognostic value of tumor angiogenesis and the potential role of antiangiogenic therapy in various gastrointestinal cancers.

METHODS

A Medline literature search was conducted using "angiogenesis" or the names of various angiogenic factors in combination with the names of gastrointestinal cancers as the key words.

RESULTS

Several studies have demonstrated a significant prognostic impact of tumor microvessel density and tumor expression of angiogenic factors, in particular vascular endothelial growth factor (VEGF), in various gastrointestinal cancers. A few studies have suggested that circulating VEGF might be a useful prognostic marker. However, results were not consistent across all studies and were limited by the retrospective nature of most studies. Antiangiogenic therapy has been shown to be effective against all common gastrointestinal cancers in preclinical studies, but currently there are few clinical data with regard to antiangiogenic therapy in gastrointestinal cancers.

CONCLUSIONS

There is mounting evidence to suggest that assessment of tumor angiogenesis might provide a novel approach of prognostication in patients with gastrointestinal cancers. However, current results from retrospective studies need to be validated by prospective studies. Antiangiogenic therapy is a promising strategy of cancer treatment that might be particularly useful in combination therapy for unresectable cancers or as an adjuvant therapy for resectable tumors.

The angiogenic switch for vascular endothelial growth factor (VEGF)-A, VEGF-B, VEGF-C, and VEGF-D in the adenoma-carcinoma sequence during colorectal cancer progression

Angiogenesis is essential for tumour growth and metastasis. It is controlled by angiogenic factors, one of the most important being vascular endothelial growth factor (VEGF)-A. Although its role has been demonstrated in many tumour types including colorectal carcinoma (CRC), the importance of the newer family members in adenoma, invasive tumour growth, and progression to a metastatic phenotype has been poorly characterized in CRC. The aim of this study was to determine the role and timing of the VEGF angiogenic switch during CRC progression. We measured the gene expression of VEGF ligands (VEGF-A, VEGF-B, VEGF-C, and VEGF-D) and their receptors (VEGFR-1, VEGFR-2, and VEGFR-3), in normal colorectal tissues (n = 20), adenomas (n = 10), and in CRC (n = 71) representing different Duke's stages using ribonuclease protection assay, semi-quantitative relative reverse transcriptase polymerase chain reaction, together with the pattern of their expression by immunohistochemistry. VEGF-A mRNA was the most abundant in colorectal tissue, followed by VEGF-B, VEGF-C, and VEGF-D. VEGF-A and VEGF-B mRNAs were significantly more abundant in adenomas (p = 0.0003 and p = 0.04 respectively) compared with normal tissues, while VEGF-A and VEGF-C were significantly increased in carcinomas compared with normal tissues (p = 0.0006 and p = 0.0009 respectively). A significantly greater amount of VEGF-C mRNA was present in carcinomas compared with adenomas (p = 0.03), whereas there was a significant reduction of VEGF-B in carcinomas compared with adenomas (p = 0.0002). VEGF-D mRNA was significantly more abundant in normal tissues than in adenomas (p = 0.0001) and carcinomas (p < 0.0001). In normal tissues distant from the primary tumour, there was a significantly greater amount of VEGF-A and VEGF-D mRNA in patients with Duke's B and Duke's C respectively, compared with Duke's A stage tumours (p = 0.04 and p = 0.01 respectively). Immunohistochemistry showed low basal levels of all ligands in histologically normal tissues and their expression in the epithelium of tumours reflected the levels of mRNA expression identified. VEGF-A and VEGF-C mRNA levels correlated significantly with tumour grade (p = 0.01 and p = 0.01 respectively) and tumour size (p = 0.001 and p = 0.01 respectively), but not with patient age, sex, presence of infiltrative margin, lymphocytic response, vascular invasion, Duke's stage, or lymph node involvement (p > 0.05). VEGF-B mRNA correlated with an infiltrative margin (p = 0.04) but no other clinicopathological variable, and expression of VEGF-D demonstrated no association with any parameter examined. VEGFR-1 was significantly correlated with tumour grade (p = 0.02), Duke's stage (p < 0.001), and lymph node involvement (p = 0.004), VEGFR-2 with lymph node involvement (p = 0.02), and VEGFR-3 did not correlate with any of the clinicopathological variables tested. These results suggest that VEGF-A and VEGF-B play a role early in tumour development at the stage of adenoma formation and that VEGF-C plays a role in advanced disease when there is more likelihood of metastatic spread. The finding of increased levels of VEGF-A and VEGF-D expression in normal tissues collected from a site distant from the primary tumour indicates changes in the surrounding tumour environment that may enhance the subsequent spread of tumour cells.

Vascular permeability factor/vascular endothelial growth factor: a critical cytokine in tumor angiogenesis and a potential target for diagnosis and therapy

Vascular endothelial growth factor A (VEGF-A), the founding member of the vascular permeability factor (VPF)/VEGF family of proteins, is an important angiogenic cytokine with critical roles in tumor angiogenesis. This article reviews the literature with regard to VEGF-A's multiple functions, the mechanisms by which it induces angiogenesis, and its current and projected roles in clinical oncology. VEGF-A is a multifunctional cytokine that is widely expressed by tumor cells and that acts through receptors (VEGFR-1, VEGFR-2, and neuropilin) that are expressed on vascular endothelium and on some other cells. It increases microvascular permeability, induces endothelial cell migration and division, reprograms gene expression, promotes endothelial cell survival, prevents senescence, and induces angiogenesis. Recently, VEGF-A has also been shown to induce lymphangiogenesis. Measurements of circulating levels of VEGF-A may have value in estimating prognosis, and VEGF-A and its receptors are potential targets for therapy. Recognized as the single most important angiogenic cytokine, VEGF-A has a central role in tumor biology and will likely have an important role in future approaches designed to evaluate patient prognosis. It may also become an important target for cancer therapy.

Vascular endothelial growth factor is increased in aqueous humor of glaucomatous eyes

PURPOSE

To assess the concentrations of vascular endothelial growth factor (VEGF) in aqueous humor in eyes with and without glaucoma.

METHODS

Concentrations of VEGF were measured using a sandwich ELISA kit in aqueous humor aspirates taken during anterior segment surgery from 87 patients, of whom 54 had glaucoma (27 primary open-angle glaucoma, 8 angle-closure glaucoma, 16 exfoliative glaucoma) and 33 had cataract only.

RESULTS

Vascular endothelial growth factor was detected in all samples. The concentration in eyes with cataract only without glaucoma was 102.4 +/- 29.7 pg/mL (mean +/- SD), which was significantly lower than that from eyes with glaucoma (146.7 +/- 51.8 pg/mL). There were no significant differences between primary open-angle glaucoma (140.4 +/- 51.0 pg/mL), angle-closure glaucoma (142.8 +/- 40.2 pg/mL), and exfoliative glaucoma (158.6 +/- 58.9 pg/mL). An unusually high VEGF concentration was detected in one eye with neovascular glaucoma (759 pg/mL) and two eyes with uveitic glaucoma (322 pg/mL). No effect of age, gender, or previous history of medical, laser, or surgical treatment of the aqueous humor VEGF concentration could be detected ( > 0.05). Aqueous humor and plasma VEGF concentrations were measured and compared in 46 patients. The aqueous humor VEGF concentration (144.2 +/- 107.9 pg/mL) was significantly higher ( < 0.01) than the plasma concentration (79.2 +/- 46.1 pg/mL). No significant correlation was found between aqueous humor and plasma VEGF concentrations.

CONCLUSION

Aqueous VEGF concentration is increased in eyes with glaucoma.

Tumour markers as early predictors of response to chemotherapy in advanced colorectal carcinoma

BACKGROUND

To evaluate the reliability and validity of serum carcinoembryonic antigen (CEA), tissue polypeptide-specific antigen (TPS), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in monitoring palliative chemotherapy in advanced colorectal cancer (ACRC).

METHODS

Serum was prospectively collected from 87 patients with ACRC treated with first-line 5-fluorouracil and leucovorin before and 2, 4 and 10 weeks after induction.

RESULTS

Eight patients had normal baseline TPS levels, and these patients had a favourable outcome with prolonged survival and a higher rate of objective responses than patients with elevated TPS levels. At 10 weeks, all responders had a decreasing TPS value. The sensitivity for a decrease of >25% using TPS was 83% and 86% for objective and subjective responses, respectively, and the specificity was 65% and 72%, respectively. CEA had, in the same setting, a sensitivity of 45% and 46%, respectively, and the specificity was 88%. VEGF was elevated in 54% of the patients and bFGF in 15% of the patients. The VEGF values decreased during therapy in 94% of the patients, but the changes in serial VEGF values did not correlate with survival or response. Tumour markers used together did not enhance the predictive values of TPS alone.

CONCLUSIONS

Repeated measurements of CEA, VEGF and bFGF in serum are of limited value in monitoring chemotherapy in ACRC. TPS seems to be of greater interest, but does not predict exactly which patients are going to have a positive outcome of palliative chemotherapy.

Non-invasive methods of assessing angiogenesis and their value in predicting response to treatment in colorectal cancer

BACKGROUND

Tumour neoangiogenesis can be assessed non-invasively by measuring angiogenic cytokine concentrations in peripheral circulation and by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The aim of this study was to assess whether these methods can predict and monitor response to treatment in patients with rectal cancer treated with preoperative chemoradiotherapy.

METHODS

Serum and plasma vascular endothelial growth factor levels were measured in 31 patients with T3/T4 rectal cancers before quantitating tumour permeability (ln Ktrans) by DCE-MRI. Sixteen patients receiving preoperative chemoradiotherapy had serial vascular endothelial growth factor (VEGF) and DCE-MRI measurements. Response to treatment was assessed using World Health Organization criteria.

RESULTS

Serum VEGF and ln Ktrans correlated before treatment (r = 0.48, P = 0.01). Responsive tumours (n = 8) had higher pretreatment permeability values than non-responsive tumours (n = 8) (mean ln Ktrans - 0.46 and - 0.72 respectively; P = 0.03). Compared with pretreatment values, responsive tumours showed a marked reduction in permeability at the end of treatment (mean ln Ktrans - 0.46 and - 0.86 respectively; P = 0.04). Pretreatment serum VEGF levels were not statistically different between the two groups.

CONCLUSION

Rectal tumours with higher permeability at presentation appear to respond better to chemoradiotherapy than those of lower permeability. This may allow preselection of appropriate tumours for these regimens, with patients with low-permeability tumours being considered for alternative therapies.

Phase II study of the antiangiogenesis agent thalidomide in recurrent or metastatic squamous cell carcinoma of the head and neck

BACKGROUND

Thalidomide has been shown to have antiangiogenic effects in preclinical models as well as a significant antitumor effect in hematologic tumors such as multiple myeloma. The authors performed this Phase II study to determine the activity, toxicity profile, and antiangiogenic effect of thalidomide in patients with locoregionally recurrent or metastatic squamous cell carcinoma of the head and neck.

METHODS

Twenty-one patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with single-agent thalidomide. All patients had received radiation therapy, and most had undergone surgery (95%) and/or chemotherapy (90%). Thalidomide was initiated at 200 mg;3>daily and increased to a target dose of 1000 mg daily. Patients continued treatment until disease progression, unacceptable toxicity, or death occurred.

RESULTS

All 21 patients eventually developed progressive disease. Median time to progression was 50 days (95% confidence interval, 28-70), with median overall survival time of 194 days (95% lower confidence boundary, 151), similar to the progression and survival times reported for this patient group with other agents. Thalidomide was generally well tolerated, with few patients experiencing Grades 3 to 4 toxicities. Serum vascular endothelial growth factor and basic fibroblast growth factor levels increased in six of seven patients, for whom paired serum samples were available and all of whom had progressive disease.

CONCLUSIONS

In this heavily pretreated population of patients with advanced squamous cell carcinoma of the head and neck, thalidomide does not appear to have single-agent antitumor activity. Further evaluation of the mechanism of action of thalidomide is indicated. Potentially, future evaluations of thalidomide may be performed in combination with other antiangiogenic or cytotoxic agents in patients with earlier stage disease or in patients with minimal residual disease.

Predictive and prognostic markers in gastrointestinal cancers

As the roles of specific genes and their functions in cancer etiology and progression become defined, the necessity of looking at multiple genes and their interaction becomes clearer. In gastrointestinal cancer, tumor suppressor and promoter genes, cell cycle control and angiogenic factors, repair genes, and metabolic genes have been examined as they relate to prognosis and therapeutic outcomes. To date, most correlative studies for specific molecular parameters have been done retrospectively. Methodologies, sample sizes, and definitions differ. The following analysis provides a brief review of the current state of knowledge and recent research on the most commonly studied molecular markers, and the newer areas of inquiry attempting to define how to use molecular-genetic features of individual tumors as targets for more effective therapies. Consideration is given to the design of trials employing molecular targets as outcome factors.

Pitfalls in the Measurement of Circulating Vascular Endothelial Growth Factor

Background: Vascular endothelial growth factor (VEGF) is a protein with antiapoptotic, mitogenic, and permeability-increasing activities specific for vascular endothelium. VEGF mRNA, which has five isoforms, is produced by nonmalignant cells in response to hypoxia and inflammation and by tumor cells in constitutively high concentrations. Because VEGF plays a crucial role in physiological and pathophysiological angiogenesis, measurements of circulating VEGF are of diagnostic and prognostic value, e.g., in cardiovascular failures, inflammatory diseases, and malignancies. However, there are major quantitative differences in the published results. This review attempts to identify reasons for these disparities.

Approach: The literature was reviewed through a Medline search covering 1995 to 2000. A selection of exemplary references had to be made for this perspective overview.

Content: Data are included from studies on healthy humans, gynecological patients, and persons suffering from inflammatory or malignant diseases. The results indicate that competitive immunoassays detect the total amount of circulating VEGF, which enables observations regarding the increase in VEGF in pregnancy and preeclampsia to be made. In these cases, capture immunoassays utilizing neutralizing antibodies are insufficient because of an accompanying increase in VEGF-binding soluble receptors (sFlt-1). Measurements of circulating free VEGF are useful for study of malignant diseases, which are associated with both genetically and hypoxia-induced overproduction of VEGF. The VEGF isoform specificity of the antibodies is also critical because both VEGF121 and VEGF165 are secreted. It is important to consider that platelets and leukocytes release VEGF during blood clotting.

Conclusions: Future efforts should concentrate on the balance between free VEGF, total VEGF, and sFlt-1. Plasma, rather than serum, should be used for analysis.

Clinical implications of circulating angiogenic factors in cancer patients

PURPOSE

Angiogenesis, a process fundamental to tumor growth, is regulated by angiogenic factors. This article reviews prognostic and other clinical implications of circulating angiogenic factors in cancer patients.

METHODS

A MEDLINE search of literature was performed using the names of various angiogenic factors as the key words. Studies pertaining to circulating angiogenic factors in cancer patients were reviewed. Pertinent literature regarding tumor expression of common angiogenic factors and their prognostic relevance in human cancers were also examined.

RESULTS

A substantial number of studies have demonstrated a strong association between elevated tumor expression of vascular endothelial growth factor (VEGF) and advanced disease or poor prognosis in various cancers. This supports the pivotal role of VEGF in regulating tumor angiogenesis. More recently, there is mounting evidence that the level of circulating VEGF in patients with different types of cancer may be predictive of tumor status and prognosis. Preliminary data also suggest that circulating VEGF may be useful in predicting and monitoring tumor response to anticancer therapies and in follow-up surveillance for tumor relapse. There are reports supporting the prognostic value of other circulating angiogenic factors such as basic fibroblast growth factor, platelet-derived endothelial cell growth factor, transforming growth factor-beta, and angiogenin, but their clinical significance is less conclusive because of limited data.

CONCLUSION

Circulating VEGF seems to be a reliable surrogate marker of angiogenic activity and tumor progression in cancer patients. Evaluation of circulating angiogenic factors is a promising novel approach of prognostication in cancer patients that has the advantages of being convenient and noninvasive, and it may provide new prognostic information that is not afforded by conventional clinicopathologic prognostic indicators.

Anti-angiogenesis therapy:concepts and importance of dosing schedules in clinical trials

The biological control of angiogenesis is critical to the clinical control of cancer. Understanding the mechanism of formation and regulation of new blood vessel development would open a new avenue for cancer treatment. Intense research effort has revealed a variety of factors which initiate, control and terminate the multi-stage process of angiogenesis, as well as target structures which interfere with this process. Protease inhibitors, inhibitors of the endothelial cell proliferation, suppressors of angiogenic growth factors, copper chelators, and other compounds interfering with the process of angiogenesis were screened for inhibition of tumor angiogenesis and some of them are in clinical trials. Very recently, a new term, 'metronomic dosing regimen' has been introduced, which implicates the use of the old cytostatic anticancer agents as anti-angiogenic agents. Results from recent studies will be discussed briefly and the prospects of inhibition of tumor angiogenesis as a new treatment modality will be outlined. Copyright 2000 Harcourt Publishers Ltd.