Circulating endothelial cells as biomarkers in clinical oncology

Metronomic Anti-Cancer Therapy: A Multimodal Therapy Governed by the Tumor Microenvironment

Simple Summary

Metronomic chemotherapy with different mechanisms of action against cancer cells and their microenvironment represents an exceptional holistic cancer treatment. Each type of tumor has its own characteristics, including each individual tumor in each patient. Understanding the complexity of the dynamic interactions that take place between tumor and stromal cells and the microenvironment in tumor progression and metastases, as well as the response of the host and the tumor itself to anticancer therapy, will allow therapeutic actions with long-lasting effects to be implemented using metronomic regimens. This study aims to highlight the complexity of cellular interactions in the tumor microenvironment and summarize some of the preclinical and clinical results that explain the multimodality of metronomic therapy, which, together with its low toxicity, supports an inhibitory effect on the primary tumor and metastases. We also highlight the possible use of nano-therapeutic agents as good partners for metronomic chemotherapy.

Abstract

The concept of cancer as a systemic disease, and the therapeutic implications of this, has gained special relevance. This concept encompasses the interactions between tumor and stromal cells and their microenvironment in the complex setting of primary tumors and metastases. These factors determine cellular co-evolution in time and space, contribute to tumor progression, and could counteract therapeutic effects. Additionally, cancer therapies can induce cellular and molecular responses in the tumor and host that allow them to escape therapy and promote tumor progression. In this study, we describe the vascular network, tumor-infiltrated immune cells, and cancer-associated fibroblasts as sources of heterogeneity and plasticity in the tumor microenvironment, and their influence on cancer progression. We also discuss tumor and host responses to the chemotherapy regimen, at the maximum tolerated dose, mainly targeting cancer cells, and a multimodal metronomic chemotherapy approach targeting both cancer cells and their microenvironment. In a combination therapy context, metronomic chemotherapy exhibits antimetastatic efficacy with low toxicity but is not exempt from resistance mechanisms. As such, a better understanding of the interactions between the components of the tumor microenvironment could improve the selection of drug combinations and schedules, as well as the use of nano-therapeutic agents against certain malignancies.

Study the relationship of endothelial damage / dysfunction due to occupational exposure to low dose ionizing radiation versus high dose exposure during radiotherapy

BACKGROUND

Vascular injuries caused by irradiation include acute vasculitis with neutrophil invasion, endothelial cell (EC) swelling, capillary loss, and activation of coagulator mechanisms, along with local ischemia and fibrosis. The circulating endothelial cells (CECs), increase dramatically in diseases with vascular damage.

AIM

The aim of this study is to provide data on the endothelial dysfunction due to occupational exposure to low dose ionizing radiation versus high dose exposure during radiotherapy (RT).

PATIENTS AND METHODS

This study included 100 subjects divided into three main groups: Group I: High dose exposure group: 50 breast cancer patients treated with post-operative radiotherapy. Group II: Low dose exposure group: 25 hospital radiation workers. Group III: 25 healthy volunteers' age and sex matched as control group who had never worked in radiation-related jobs. TM levels measured by enzyme linked immunosorbent assay (ELISA). Circulating endothelial cells (CEC) enumerated in peripheral blood by flow cytometric analysis of their signature receptor CD146.

RESULTS

% CD146+ cells and plasma TM were significantly increased in radiation workers and after exposure to radiotherapy treatment in breast cancer patients. When comparing patients group with radiation workers group, we found significant elevation in plasma TM in radiation workers while insignificant difference was found in % CD146+ cells.

CONCLUSION

CECs and plasma TM both are increased in radiation workers and patients treated with radiotherapy. They may constitute valuable markers of endothelial injury. Workers exposed to low doses of ionizing radiation may develop significant endothelial dysfunction predisposes them to cardiovascular complications namely thrombosis, mostly due to oxidative stress among other causes.

Flow cytometric analysis of circulating endothelial cells and endothelial progenitor cells in pediatric solid tumors: prognostic impact on treatment response and survival

BACKGROUND AND AIM

Solid tumors, including pediatric malignancies, depend on angiogenesis for tumor growth, invasion, and metastases. We aimed to evaluate the prognostic impact of circulating endothelial cells (CECs) and endothelial progenitor cells (EPCs) on treatment response and survival of pediatric patients with solid tumors.

METHODS

A prospective study included 70 patients with different pediatric solid tumors treated with different types of chemotherapy and 20 age and sex-matched healthy children as controls. Blood samples collected at diagnosis then on day 7 and day 21 after chemotherapy. CECs and EPCs were evaluated using flow cytometry.

RESULTS

The mean levels of CECs and EPCs of patients at diagnosis were significantly higher than controls (85.29 ± 24.78 and 26.1 ± 9.11 versus 20.08 ± 6.65; and EPCs; 2.78 ± 1.48, respectively; P < 0.001 for both). The highest levels of CECs were observed in patients with rhabdomyosarcoma (RMS). An overall increase was reported in CECs, and after the first cycle of chemotherapy, that was significantly correlated to treatment response and overall survival.

CONCLUSION

Pediatric patients with solid tumors have elevated levels of CECs and EPCs with more elevation after chemotherapy. The magnitude of increase of CECs occurred on day 7 after chemotherapy may be considered as an early predictor of response to therapy and outcome in pediatric patients with solid tumors.

CD276-Positive Circulating Endothelial Cells Do Not Predict Response to Systemic Therapy in Advanced Colorectal Cancer

CD276 can discriminate between tumor derived and normal CECs (circulating endothelial cells). We evaluated whether CD276⁺CEC is a clinically relevant biomarker to predict response to palliative systemic therapy in patients with metastatic colorectal cancer (mCRC). Samples were prospectively collected from patients with mCRC enrolled in the ORCHESTRA trial (NCT01792934). At baseline and after three cycles of 5-fluorouracil/leucovorin and oxaliplatin ± bevacizumab, CECs were measured by flowcytometry (CD34⁺CD45^negCD146⁺DNA⁺; and CD276⁺). A clinically relevant cut-off value of (CD276⁺)CECs was determined as 100% sensitivity (and 80% specificity in 95% confidence interval) identifying patients with progressive disease within 6 months. There were 182 baseline samples and 133 follow up samples available for analysis. CEC and CD276⁺CEC counts significantly increased during treatment from 48 to 90 CEC/4 mL (p = 0.00) and from 14 to 33 CD276⁺CEC/4 mL (p = 0.00) at baseline and at first evaluation, respectively. CEC and CD276⁺CEC counts were not predictive for poor response (area under the curve (AUC) 0.53 for CEC and AUC 0.52 for CD276⁺CEC). Despite numerical changes during therapy, CEC and CD276⁺CEC counts do not adequately predict poor response to first line palliative systemic therapy in patients with mCRC.

Circulating Proangiogenic Cells and Proteins in Patients with Glioma and Acute Myocardial Infarction: Differences in Neovascularization between Neoplasia and Tissue Regeneration

Although extensive angiogenesis takes place in glial tumors, antiangiogenic therapies have remained without the expected success. In the peripheral circulation of glioma patients, increased numbers of endothelial precursor cells (EPCs) are present, potentially offering targets for antiangiogenic therapy. However, for an antiangiogenic therapy to be successful, the therapy should specifically target glioma-related EPC subsets and secreted factors only. Here, we compared the EPC subsets and plasma factors in the peripheral circulation of patients with gliomas to acute myocardial infarctions. We investigated the five most important EPC subsets and 21 angiogenesis-related plasma factors in peripheral blood samples of 29 patients with glioma, 14 patients with myocardial infarction, and 20 healthy people as controls, by FACS and Luminex assay. In GBM patients, all EPC subsets were elevated as compared to healthy subjects. In addition, HPC and KDR⁺ cell fractions were higher than in MI, while CD133⁺ and KDR⁺CD133⁺ cell fractions were lower. There were differences in relative EPC fractions between the groups: KDR⁺ cells were the largest fraction in GBM, while CD133⁺ cells were the largest fraction in MI. An increase in glioma malignancy grade coincided with an increase in the KDR⁺ fraction, while the CD133⁺ cell fraction decreased relatively. Most plasma angiogenic factors were higher in GBM than in MI patients. In both MI and GBM, the ratio of CD133⁺ HPCs correlated significantly with elevated levels of MMP9. In the GBM patients, MMP9 correlated strongly with levels of all HPCs. In conclusion, the data demonstrate that EPC traffic in patients with glioma, representing neoplasia, is different from that in myocardial infarction, representing tissue regeneration. Glioma patients may benefit from therapies aimed at lowering KDR⁺ cells and HPCs.

Lenvatinib, a molecule with versatile application: from preclinical evidence to future development in anti-cancer treatment

Lenvatinib is an emerging multi-kinase inhibitor with a preferential anti-angiogenic activity, which has shown efficacy in the treatment of renal cell carcinoma, differentiated thyroid cancer and hepatocellular carcinoma. It inhibits vascular endothelial growth factor receptor family (VEGFR1–3), fibroblast growth factor receptor family (FGFR1–4), platelet-derived growth factor receptor–alpha (PDGFRα), tyrosine-kinase receptor (KIT) and rearranged during transfection receptor (RET). In this review we have evaluated the development from bench to bedside of lenvatinib. PubMed, MEDLINE and clinicaltrials.gov are the sources of data. Furthermore, the preclinical in vitro and in vivo data, as well as efficacy and toxicity results of lenvatinib in the clinic, are presented and discussed. Treatment with lenvatinib causes side effects (hypertension, proteinuria, fatigue and diarrhea), which are predominantly related to the inhibition of angiogenesis. For these reasons, the identification of biomarkers of efficacy and resistance to lenvatinib is a key challenge in order to select responsive patients. This review provides an overview on lenvatinib's clinical use, perspectives and indications for future development.

Circulating endothelial cells and microparticles as diagnostic and prognostic biomarkers in small-cell lung cancer

OBJECTIVES

It has been proposed that circulating endothelial cells (CECs) and microparticles (MPs) may be useful for the assessment of patients with non-small-cell lung cancer (NSCLC). However, little is known about the potential clinical relevance of these biomarkers in small-cell lung cancer (SCLC). Therefore, we investigated the utility of baseline levels of CECs and MPs in SCLC patients.

MATERIALS AND METHODS

An immunomagnetic separation (IMS) technique was used to isolate and quantify CECs in the peripheral blood, while plasma samples were analyzed using flow cytometry for the measurement of circulating MPs.

RESULTS

We prospectively collected data from 56 patients and 41 healthy individuals. Forty-three patients presented at initial diagnosis and 13 patients presented at relapse. Baseline levels of CECs and MPs were significantly higher in SCLC patients either at initial diagnosis or at relapse than in healthy subjects (p < 0.0002 and p < 0.007, respectively). However, estimated tumor volume (ETV) was significantly correlated with basal MP values (p < 0.0001) but not with pretreatment CECs (p =  0.57). The amount of baseline CECs and MPs was significantly lower in patients with an objective response (OR, n = 23) than in those with progressive disease (PD, n = 15) after treatment (p =  0.016 and 0.05, respectively). With cut-off values of 110 cells/mL for CECs and 1257 events/μL for MPs according to receiver operating characteristics (ROC) analysis, baseline levels of these biomarkers were not significantly correlated with either progression-free survival (PFS) or overall survival (OS). However, patients with 6-month PFS displayed significantly decreased pretreatment CEC counts (p =  0.042), whereas basal MP values significantly increased in 1-year survivors compared with those in non-survivors (p =  0.05).

CONCLUSION

Our results suggest that baseline CECs and MPs may be predictive biomarkers of tumor response and long-term survival in SCLC patients.

Current Status and Study Progress of Recombinant Human Endostatin in Cancer Treatment

Angiogenesis plays fundamentally critical roles in solid-tumor pathogenesis, growth, invasion and metastasis. Endostatin, one of the most potent anti-angiogenic factors, was first isolated in Folkman's lab in 1997, and was reported to dramatically shrink tumor blood formation. But its insoluble and unstable nature coupled with the high cost of synthesizing the endostatin protein doomed it for clinical cancer treatment. Intrigued by Folkman's pioneering discoveries, Chinese scientists found a way to refold the protein, making it cost-effective to manufacture a recombinant human endostatin, a soluble and stable form of endostatin. A number of clinical studies have demonstrated the significant survival benefit of rh-endostatin in treating late stage non-small-cell lung carcinoma (NSCLC) and, as a result, rh-endostatin (Endostar®) was approved by the State Food and Drug Administration of China (CFDA) in September of 2005 as a treatment option for NSCLC. Since then, increasing bodies of clinical data and experience have been obtained from a variety of other different cancers, such as small cell lung cancer, NSCLC in other settings, including malignant serous effusion, melanoma, colon cancer, gastric cancer, breast cancer, nasopharyngeal cancers, and others. This review aims at summarizing current clinical data of rh-endostatin including its survival benefits, optimized dosages, routes of administration, recommended duration and frequency of treatment, predictive biomarkers, and its safety profile in lung cancers as well as other cancers.

Bevacizumab specifically decreases elevated levels of circulating KIT+CD11b+ cells and IL-10 in metastatic breast cancer patients

BACKGROUND

Whether bevacizumab exerts its anti-tumor properties through systemic effects beyond local inhibition of angiogenesis and how these effects can be monitored in patients, remain largely elusive. To address these questions, we investigated bone marrow-derived cells and cytokines in the peripheral blood of metastatic breast cancer patients undergoing therapy with bevacizumab.

METHODS

Circulating endothelial cells (CEC), circulating endothelial progenitor (CEP) and circulating CD11b+ cells in metastatic breast cancer patients before and during therapy with paclitaxel alone (n = 11) or in combination with bevacizumab (n = 10) were characterized using flow cytometry, real time PCR and RNASeq. Circulating factors were measured by ELISA. Aged-matched healthy donors were used as baseline controls (n = 12).

RESULTS

Breast cancer patients had elevated frequencies of CEC, CEP, TIE2+CD11b+ and KIT+CD11b+ cell subsets. CEC decreased during therapy, irrespective of bevacizumab, while TIE2+CD11b+ remained unchanged. KIT+CD11b+ cells decreased in response to paclitaxel with bevacizumab, but not paclitaxel alone. Cancer patients expressed higher mRNA levels of the M2 polarization markers CD163, ARG1 and IL-10 in CD11b+ cells and increased levels of the M2 cytokines IL-10 and CCL20 in plasma. M1 activation markers and cytokines were low or equally expressed in cancer patients compared to healthy donors. Chemotherapy with paclitaxel and bevacizumab, but not with paclitaxel alone, significantly decreased IL-10 mRNA in CD11b+ cells and IL-10 protein in plasma.

CONCLUSIONS

This pilot study provides evidence of systemic immunomodulatory effects of bevacizumab and identified circulating KIT+CD11b+ cells and IL-10 as candidate biomarkers of bevacizumab activity in metastatic breast cancer patients.

Enumeration of circulating endothelial cell frequency as a diagnostic marker in aortic valve surgery - a flow cytometric approach

Background

The frequency of circulating endothelial cells (CEC) in patients’ peripheral blood can be assessed as a direct marker of endothelial damage. However, conventional enumeration methods are extremely challenging. We developed a novel, automated approach to determine CEC frequencies and tested this method on two groups of patients undergoing conventional (CAVR) versus trans-catheter aortic valve implantation (TAVI).

Methods

CEC frequencies were assessed by a flow cytometric approach, including automated pre-enrichment of CD34 positive blood cell subpopulation and isotype controls. The efficacy and reproducibility of the CEC enumeration method was validated by spiking blood samples of healthy control donors with defined numbers of endothelial cells.

Results

CEC frequencies were significantly higher in the TAVI group before (9.8 ± 4.1 vs. 5.5 ± 2.2, p = 0.019) and 1 h after surgery (13.4 ± 5.1 vs. 8.2 ± 4.1, p = 0.030) corresponding to higher Euroscore, STS score in higher risk patients from the TAVI group. Five days after surgery, CEC frequencies became significantly higher in the more invasive CAVR group (39.0 ± 13.0 vs. 14.3 ± 4.4, p < 0.001) compared to minimally invasive TAVI approach.

Conclusions

The new flow cytometric approach might be a robust and reliable method for CEC enumeration. Initial results show that CEC frequency is a valid clinical marker for the assessment of pre-operative risk, invasiveness of surgical procedure and clinical outcome. Further studies are necessary to validate the practical clinical usefulness and the potential superiority compared to conventional markers.

Maintenance chemotherapy in children with ALL exerts metronomic-like thrombospondin-1 associated anti-endothelial effect

Maintenance chemotherapy is an important part of the treatment of ALL in children. It relies on the long-term oral administration of daily low-dose mercaptopurin and weekly low-dose methotrexate. Although it has been used in the clinic for decades, its mechanisms of action remain unclear. Here, we investigated different angiogenic and immune biomarkers to gain insights into the mechanisms of action of maintenance therapy in children with ALL. We thus monitored circulating endothelial cells (CEC), endothelial progenitor cells (EPC) and endothelial microparticles (EMP), pro-angiogenic factors (VEGF, VEGFR-1 and Ang-2), anti-angiogenic factor thrombospondin-1 (THBS1) and regulatory T lymphocytes (Treg) in 47 children with ALL during the maintenance phase of their treatment (at treatment initiation and after 6, 12 and 18 months). We observed a statistically significant decrease in EPC and EMP counts throughout the maintenance phase associated with a significant increase in THBS1 levels. No significant change was detected in other angiogenic markers or in Treg numbers.

The results presented here indicate that maintenance therapy in children with ALL exerts its antitumor activity at least in part through anti-angiogenic effects, similar to those induced by metronomic chemotherapy. Larger studies are now warranted to validate these findings and determine their clinical implications.

Flow cytometric analysis of circulating endothelial cells and endothelial progenitors for clinical purposes in oncology: A critical evaluation

Malignant tumors are characterized by uncontrolled cell growth and metastatic spread, with a pivotal importance of the phenomenon of angiogenesis. For this reason, research has focused on the development of agents targeting the vascular component of the tumor microenvironment and regulating the angiogenic switch. As a result, the therapeutic inhibition of angiogenesis has become an important component of anticancer treatment, however, its utility is partly limited by the lack of an established methodology to assess its efficacy in vivo. Circulating endothelial cells (CECs), which are rare in healthy subjects and significantly increased in different tumor types, represent a promising tool for monitoring the tumor clinical outcome and the treatment response. A cell population circulating into the blood also able to form endothelial colonies in vitro and to promote vasculogenesis is represented by endothelial progenitor cells (EPCs). The number of both of these cell types is extremely low and they cannot be identified using a single marker, therefore, in absence of a definite consensus on their phenotype, require discrimination using combinations of antigens. Multiparameter flow cytometry (FCM) is ideal for rapid processing of high numbers of cells per second and is commonly utilized to quantify CECs and EPCs, however, remains technically challenging since there is as yet no standardized protocol for the identification and enumeration of these rare events. Methodology in studies on CECs and/or EPCs as clinical biomarkers in oncology is heterogeneous and data have been obtained from different studies leading to conflicting conclusions. The present review presented a critical review of the issues that limit the comparability of results of the most significant studies employing FCM for CEC and/or EPC detection in patients with cancer.

Simultaneous detection of circulating immunological parameters and tumor biomarkers in early stage breast cancer patients during adjuvant chemotherapy

BACKGROUND

Chemotherapy-induced immune suppression has mainly been studied in patients with advanced cancer, but the influence of chemotherapy on the immune system in early stage cancer patients has so far not been studied systematically. The aim of the present study was to monitor the immune system during anthracycline- and taxane-based adjuvant chemotherapy in early stage breast cancer patients, to assess the impact of circulating tumor cells on selected immune parameters and to reveal putative angiogenic effects of circulating endothelial cells.

METHODS

Peripheral blood samples from 20 early stage breast cancer patients were analyzed using a flow cytometric multi-color of antibodies to enumerate lymphocyte and dendritic cell subsets, as well as endothelial and tumor cells. An enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of various serological factors.

RESULTS

During chemotherapy, all immunological parameters and angiogenesis surrogate biomarkers showed significant decreases. The numbers of circulating tumor cells showed significant inverse correlations with the numbers of T helper cells, a lymphocyte subset directly related to effective anti-tumor responses. Reduced T helper cell numbers may contribute to systemic immunosuppression and, as such, the activation of dormant tumor cells.

CONCLUSIONS

From our results we conclude that adjuvant chemotherapy suppresses immune function in early stage breast cancer patients. In addition, we conclude that the presence of circulating tumor cells, defined as pan-cytokeratin(+), CD326(+), CD45(-) cells, may serve as an important indicator of a patient's immune status. Further investigations are needed to firmly define circulating tumor cells as a predictor for the success of breast cancer adjuvant chemotherapy.

Circulating endothelial cells for evaluation of tumor response in non-small cell lung cancer patients receiving first-line chemotherapy

BACKGROUND

Circulating endothelial cells (CECs) reflect the neovascularization in the tumor mass. We therefore investigated the potential role of CEC kinetics after first-line chemotherapy in advanced non-small cell lung cancer (NSCLC) patients.

METHODS

Peripheral blood samples were obtained from 45 healthy subjects and 51 naïve patients with advanced NSCLC. Quantification of CD146+ CECs was performed using immunomagnetic separation (IMS).

RESULTS

Pretreatment and posttreatment CEC levels in NSCLC patients were significantly higher than in healthy subjects (p&lt;0.0001). An objective response was achieved after chemotherapy with partial response (PR) or stable disease (SD) in 26 patients, whereas the remaining 25 patients had progressive disease (PD). Baseline CEC levels were significantly higher in PR/SD patients than in PD patients (p = 0.039). After chemotherapy, CEC count significantly decreased in PR/SD patients (p = 0.014) and increased in patients with PD (p = 0.019). Moreover, there was a significant difference in the percentage change of CEC counts between the 2 groups (p = 0.0016). No significant difference in the median progression-free survival and overall survival (OS) was observed between patients with high baseline CEC counts and those with low baseline CEC levels. However, patients with high percentage change in CEC count had longer OS than those with low percentage change after chemotherapy (p = 0.05).

CONCLUSIONS

Changes in CEC counts after chemotherapy reflect tumor response in advanced NSCLC patients. Moreover, high percentage changes in CEC counts after chemotherapy may predict longer OS in advanced NSCLC. High baseline CEC levels might be an indicator of tumor response in advanced NSCLC patients after first-line chemotherapy.

Increased pre-surgical numbers of endothelial progenitor cells and circulating endothelial cells in colorectal cancer fail to predict outcome

INTRODUCTION

The endothelium and angiogenesis are therapeutic targets in cancer. Response to treatment may be assessed by laboratory plasma markers such as circulating endothelial cells (CECs), endothelial progenitor cells (EPCs), von Willebrand factor (vWf), soluble E selectin, vascular endothelial growth factor (VEGF) and angiogenin. We hypothesised that these markers, obtained before surgery, would predict 2-year outcome after surgery with or without anti-angiogenic therapy for colorectal cancer (CRC).

METHODS

We recruited 154 patients with CRC, of whom 51 were treated with surgery alone, 74 were treated with standard chemotherapy (5-fluorouracil) and 29 were treated with standard chemotherapy plus anti-VEGF therapy (Avastin). Peripheral blood was taken before surgery. CD34(+)/CD45(-)/CD146(+) CECs and CD34(+)/CD45(-)/CD309 [KDR](+) EPCs were measured by flow cytometry and plasma markers by ELISA.

RESULTS

After a mean of 2.1 years follow-up (range 1.9-2.3 years), 52 of the patients (33.7 %) experienced a poor outcome (radiological and/or histological evidence of tumour spread or recurrence, or death [n = 26]). In univariate analysis, poor outcome was linked to Dukes' stage (p < 0.001), American Joint Committee on Cancer (AJCC) stage (p < 0.001), type of treatment (surgery alone, standard chemotherapy with or without anti-antigenic therapy) (p = 0.047), CECs (p < 0.02) and EPCs (p < 0.01). In subsequent binary logistic regression analysis, only Dukes' stage (hazard ratio 2.3, 95 % confidence interval 1.0-5.3, p = 0.047) and modified AJCC stage (4.62, 1.88-11.33, p < 0.001) predicted a poor outcome.

CONCLUSION

Endothelial cell markers (CECs, EPCs, vWf, soluble E selectin) and growth factors (VEGF and angiogenin), measured before surgery, have nothing extra to offer in predicting 2-year outcome in colorectal cancer when compared to Dukes' or AJCC stage.

CD144, CD146 and VEGFR-2 properly identify circulating endothelial cell

Studies evaluating circulating endothelial cells by flow cytometry are faced by a lack of consensus about the best combination of monoclonal antibodies to be used. The rarity of these cells in peripheral blood, which represent 0.01% of mononuclear cells, drastically increases this challenge.

Objective

The aim of this study is to suggest some combinations of markers that would safely and properly identify these cells.

Methods

Flow cytometry analysis of circulating endothelial cells was performed applying three different panels composed of different combinations of the CD144, CD146, CD31, CD133, CD45 and anti-Vascular endothelial growth factor receptor-2 antibodies.

Results

In spite of the rarity of the events, they were detectable and presented similar inter-person numbers of circulating endothelial cells.

Conclusion

The combination of markers successfully identified the circulating endothelial cells in healthy individuals, with the use of three different panels confirming the obtained data as reliable.

Circulating endothelial cells and their subpopulations: role as predictive biomarkers in antiangiogenic therapy for colorectal cancer

Several anticancer therapies have been developed to block angiogenesis, a key mechanism in tumor growth and metastasis. The predominantly cytostatic action of these compounds makes an assessment of their clinical activities inadequate if based only on the reduction of the tumor dimensions, as this may not reflect their true biologic efficacy. Thus, it is crucial to identify biomarkers that permit the recognition of potentially responsive subjects and to spare toxicity in those who are unlikely to benefit from treatment. Circulating endothelial cells (CECs) have been recently indicated as potential surrogate biomarkers of angiogenesis in several types of cancer. The possibility of rapidly quantifying these cells represents a promising tool for monitoring the clinical outcome of tumors with the potential to assess response to various treatments. However, the identification and quantification of CECs is technically difficult and not well standardized. A variety of methods to detect CECs in patients with solid tumors have been used; these are based on different technical approaches, combinations of surface markers, sample handling, and staining protocols. With an expanding interest in the field of potential clinical applications for CECs in oncology, the development of standardized protocols for analysis is mandatory. The aim of this review was to critically summarize the available data concerning the clinical value of CECs and their subpopulations as biomarkers of antiangiogenic therapy in patients with metastatic colorectal cancer.

Circulating endothelial cells as a biomarker in non-small cell lung cancer patients: correlation with clinical outcome

BACKGROUND

Circulating endothelial cells (CECs) have been proposed as a biomarker for the assessment of patients with solid tumors. However, few data are available in non-small cell lung cancer (NSCLC). We therefore analyzed the clinical significance of CECs in newly diagnosed NSCLC patients. In addition, we tried to determine the prognostic value of CECs in NSCLC.

METHODS

In this prospective study, 151 newly diagnosed NSCLC patients and 25 healthy volunteers were included. Furthermore, 25 patients with a partial response (n=15) or stable disease (n=10) after treatment were evaluated at recurrence with a mean follow-up of 117 days (range: 47-364 days). CECs were counted using magnetic beads coupled to a specific antibody against CD146.

RESULTS

The pre-treatment CEC count was significantly higher in patients with all histological subtypes of NSCLC than in healthy volunteers (p&lt;0.0001). High baseline CEC counts were significantly correlated with advanced clinical stages (p=0.026), weight loss (p=0.03), and poorly differentiated NSCLC (p=0.02). The amount of CECs increased significantly at recurrence compared with their amount after treatment in 20/21 assessable patients (p=0.0001). Nevertheless, there was no significant correlation between baseline CEC count and median duration of progression-free survival (p=0.402).

CONCLUSIONS

Increased CEC counts were present in patients with newly diagnosed NSCLC compared with healthy subjects. Elevated levels of baseline CECs correlated with high-risk factors in NSCLC. In addition, increased CEC count during follow-up seems to be correlated with recurrence in NSCLC patients.

Biology and flow cytometry of proangiogenic hematopoietic progenitors cells

During development, hematopoiesis and neovascularization are closely linked to each other via a common bipotent stem cell called the hemangioblast that gives rise to both hematopoietic cells and endothelial cells. In postnatal life, this functional connection between the vasculature and hematopoiesis is maintained by a subset of hematopoietic progenitor cells endowed with the capacity to differentiate into potent proangiogenic cells. These proangiogenic hematopoietic progenitors comprise a specific subset of bone marrow (BM)-derived cells that homes to sites of neovascularization and possess potent paracrine angiogenic activity. There is emerging evidence that this subpopulation of hematopoietic progenitors plays a critical role in vascular health and disease. Their angiogenic activity is distinct from putative "endothelial progenitor cells" that become structural cells of the endothelium by differentiation into endothelial cells. Proangiogenic hematopoietic progenitor cell research requires multidisciplinary expertise in flow cytometry, hematology, and vascular biology. This review provides a comprehensive overview of proangiogenic hematopoietic progenitor cell biology and flow cytometric methods to detect these cells in the peripheral blood circulation and BM.

Effect of standard chemotherapy and antiangiogenic therapy on plasma markers and endothelial cells in colorectal cancer

Introduction:

The importance of the endothelium in angiogenesis and cancer is undisputed, and its integrity may be assessed by laboratory markers such as circulating endothelial cells (CECs), endothelial progenitor cells (EPCs), plasma von Willebrand factor (vWf), soluble E selectin, vascular endothelial growth factor (VEGF) and angiogenin. Antiantigenic therapy may be added to standard cytotoxic chemotherapy as a new treatment modality. We hypothesised that additional antiangiogenic therapy acts in a contrasting manner to that of standard chemotherapy on the laboratory markers.

Methods:

We recruited 68 patients with CRC, of whom 16 were treated with surgery alone, 32 were treated with surgery followed by standard chemotherapy (5-flurouracil), and 20 were treated with surgery followed by standard chemotherapy plus anti-VEGF therapy (Avastin). Peripheral blood was taken before surgery, and again 3 months and 6 months later. CD34⁺/CD45⁻/CD146⁺ CECs and CD34⁺/CD45⁻/CD309[KDR]⁺ EPCs were measured by flow cytometry, plasma markers by ELISA.

Results:

In each of the three groups, CECs and EPCs fell at 3 months but were back at pre-surgery levels at 6 months (P<0.05). VEGF was lower in both 3-and 6-month samples in the surgery-only and surgery plus standard chemotherapy groups (P<0.05), but in those on surgery followed by standard chemotherapy plus anti-VEGF therapy, low levels at 3 months (P<0.01) increased to pre-surgery levels at 6 months. In those having surgery and standard chemotherapy, soluble E selectin was lower, whereas angiogenin was higher at 6 months than at baseline (both P<0.05).

Conclusions:

We found disturbances in endotheliod cells regardless of treatment, whereas VEGF returned to levels before surgery in those on antiangiogenic therapy. These observations may have clinical and pathophysiological implications.

Incidence and clinical implication of tumor cavitation in patients with advanced non-small cell lung cancer induced by Endostar, an angiogenesis inhibitor

BACKGROUND

Antiangiogenesis plays a key role in the treatment of non-small lung cancer (NSCLC). We observed the cavitation of lesions in patients with stage IIIB/IV NSCLC treated with Endostar and vinorelbine-cisplatin (NP) chemotherapy, and evaluated the imaging characteristics and clinical outcome of patients who developed tumor cavitation.

METHODS

Our study included 105 untreated NSCLC patients who received Endostar in combination with NP chemotherapy at the Tianjin Lung Cancer Center. Chest computed tomography (CT) was performed to evaluate the efficacy every two cycles. The number of activated circulating endothelial cells (aCECs) was measured by flow cytometry. Rates of tumor cavitation were documented and their clinical CT imaging data were analyzed.

RESULTS

Tumor cavitation occurred in 11 of the 105 (10.5%) patients treated with Endostar and NP. The response rates were 37.2% (35/94) in patients without cavitation, 27.3% (3/11) evaluated by Response Evaluation Criteria in Solid Tumors, and 100.0% (11/11) if evaluated by an alternate method in patients who developed cavitation. Three of the 11 cases with cavitation had a centrally located tumor. No patients had hemoptysis or any other severe side effects. Compared with patients not developing cavitation, cavity formation resulted in a longer median survival time (13.6 vs. 11.8 months, P = 0.011) and an increase in the number of aCECs (244.4/10(5) vs. 23.3/10(5), P = 0.000).

CONCLUSIONS

Intratumoral cavitation induced by Endostar is common in NSCLC patients, and is not correlated with squamous histology, tumor location or pulmonary hemorrhage. Cavitation might have a significant effect on the number of aCECs and overall prognosis.

Tumor vascularity in prostate cancer: an update on circulating endothelial cells and platelets as noninvasive biomarkers

In order to individually tailor prostate cancer (PCa) treatment, clinicians need better tools to predict prognosis and treatment response. Given the relationship between angiogenesis and cancer progression, circulating endothelial cells (CECs) and their progenitors have logically been proposed as potential biomarkers. The utility of their baseline levels and kinetics has been investigated for years. However, owing to a lack of standardization and validation of CEC and circulating endothelial progenitors enumeration protocols, results have been inconsistent in prostate and other cancers. Similarly, platelets play a significant part in cancer progression, yet the role of platelet-related biomarkers in PCa is unclear. While there have been a number of theoretically interesting platelet-related markers proposed, limited research has been conducted in PCa patients. Currently, CECs and platelets do not have a clear role as biomarkers in routine PCa care. Given the theoretical merits of these cells, prospective trials are warranted.

The synergistic effect of everolimus and chloroquine on endothelial cell number reduction is paralleled by increased apoptosis and reduced autophagy occurrence

Endothelial Progenitor Cells (EPCs), a minor subpopulation of the mononuclear cell fraction in peripheral blood, play a critical role in cancer development as they contribute to angiogenesis-mediated pathological neovascularization. In response to tumor cytokines, including VEGF, EPCs mobilize from the bone marrow into the peripheral circulation and move to the tumor bed where they incorporate into sprouting neovessels. In the present study, we evaluated the effects of everolimus (Afinitor, Novartis), a rapamycin analogue, alone or in combination with chloroquine, a 4-alkylamino substituted quinoline family member, one of the autophagy inhibitors, on EPCs biological functions. We found that either everolimus or chloroquine induce growth inhibition on EPCs in a dose-dependent manner after 72 h from the beginning of incubation. The combined administration of the two drugs to EPC was synergistic in inducing growth inhibition; in details, the maximal pharmacological synergism between everolimus and chloroquine in inducing growth inhibition on EPCs cells was recorded when chloroquine was administered 24 h before everolimus. Moreover, we have studied the mechanisms of cell death induced by the two agents alone or in combination on EPCs and we have found that the synergistic effect of combination on EPC growth inhibition was paralleled by increased apoptosis induction and reduced autophagy. These effects occurred together with biochemical features that are typical of reduced autophagic death such as increased co-immunoprecipitation between Beclin 1 and Bcl-2. Chloroquine antagonized the inhibition of the activity of Akt→4EBP1 axis mediated by everolimus and at the same time it blocked the feed-back activation of Erk-1/2 induced by RAD in EPCs. These data suggest a new strategy in order to block angiogenesis in tumours in which this process plays a key role in both the sustainment and spreading of cancer cells.

Angiogenin outperforms VEGF, EPCs and CECs in predicting Dukes' and AJCC stage in colorectal cancer

BACKGROUND

Circulating endothelial cells (CECs), endothelial progenitor cells (EPCs), Willebrand factor (vWf), soluble E-selectin, vascular endothelial growth factor (VEGF) and angiogenin are of interest in cancer vascular biology. However, few studies have looked at more than one in combination. We set out to determine which would be best in predicting the Dukes' and American Joint Committee on Cancer (AJCC) scores in colorectal cancer patients.

METHODS

We recruited 154 patients with colorectal cancer, 29 healthy controls and 26 patients with benign bowel disease. CD34(+) /CD45(-) /CD146(+) CECs and CD34(+) /CD45(-) /CD309[KDR](+) EPCs were measured by flow cytometry, plasma markers by ELISA.

RESULTS

All research indices were raised in colorectal cancer (P < 0·05) compared to control groups. Although CECs (P < 0·05), EPCs (P < 0·01) and angiogenin (P < 0·01) increased stepwise across the four Dukes' stages and four AJCC stages, only angiogenin remained significant in multiple regression analysis (P = 0·003 for Dukes, P = 0·01 for AJCC). Angiogenin levels were higher in Dukes' stages C and D compared to stage A, and AJCC stages 4-6 and 7-10 compared to stage 1 (all P < 0·05). Adding a second research marker to angiogenin did not markedly improve this relationship.

CONCLUSION

Although we found disturbances in endotheliod cells and plasma markers of the endothelium and growth factors, only angiogenin levels were independently associated with progression of the Dukes' stage and AJCC stage, with the association with Duke's stage being stronger. We suggest that angiogenin is a potential biomarker in risk stratification for colorectal cancer, and may aid clinical decision making.

Human endothelial progenitor cells

Human endothelial progenitor cells (EPCs) have been generally defined as circulating cells that express a variety of cell surface markers similar to those expressed by vascular endothelial cells, adhere to endothelium at sites of hypoxia/ischemia, and participate in new vessel formation. Although no specific marker for an EPC has been identified, a panel of markers has been consistently used as a surrogate marker for cells displaying the vascular regenerative properties of the putative EPC. However, it is now clear that a host of hematopoietic and vascular endothelial subsets display the same panel of antigens and can only be discriminated by an extensive gene expression analysis or use of a variety of functional assays that are not often applied. This article reviews our current understanding of the many cell subsets that constitute the term EPC and provides a concluding perspective as to the various roles played by these circulating or resident cells in vessel repair and regeneration in human subjects.

Endothelial progenitor cell: a blood cell by many other names may serve similar functions

The first reports of circulating cells that displayed the capacity to repair and regenerate damaged vascular endothelial cells as progenitor cells for the endothelial lineage (EPC) were met with great enthusiasm. However, the cell surface antigens and colony assays used to identify the putative EPC were soon found to overlap with those of the hematopoietic lineage. Over the past decade, it has become clear that specific hematopoietic subsets play important roles in vascular repair and regeneration. This review will provide some overview of the hematopoietic hierarchy and methods to segregate distinct subsets that may provide clarity in identifying the proangiogenic hematopoietic cells. This review will not discuss those circulating viable endothelial cells that play a role as EPC and are called endothelia colony-forming cells. The review will conclude with identification of some roadblocks to progress in the field of identification of circulating cells that participate in vascular repair and regeneration.

Profiles of circulating endothelial cells and serum cytokines during adjuvant chemoradiation in rectal cancer patients

INTRODUCTION

This research aimed to demonstrate the correlation of circulating endothelial cells (CECs) count and serum cytokine levels with side effects and prognosis in rectal cancer patients receiving adjuvant chemoradiation.

METHODS

Eleven patients received proctectomy, chemoradiotherapy and follow-up for 4 years. Fifty-five blood samples were taken before radiation and during the course. The quantities of CECs were estimated by flow cytometry, and serological factors were measured by ELISA.

RESULTS

The CEC level in patients without tumor recurrence was significantly lower than in patients with tumor recurrence (p < 0.01). The IL-6 and TGF-β1 levels exhibited a similar profile (p < 0.01). For morbidity, the mean CEC level in patients with grade 3 diarrhea was significantly greater than patients with grades 1 (p < 0.001) and 2 diarrhea (p < 0.005).

CONCLUSIONS

Levels of CECs, serum IL-6, TGF-β1 and TNF-α during post-operative chemoradiation in rectal cancer patients might be candidate biomarkers for prognosis and morbidity (NCT00325871).

Circulating endothelial cells and microparticles as prognostic markers in advanced non-small cell lung cancer

Background

Circulating endothelial cells and microparticles have prognostic value in cancer, and might be predictors of response to chemotherapy and antiangiogenic treatments. We have investigated the prognostic value of circulating endothelial cells and microparticles in patients treated for advanced non-small cell lung cancer.

Methodology/Principal Findings

Peripheral blood samples were obtained from 60 patients before first line, platinum-based chemotherapy +/− bevacizumab, and after the third cycle of treatment. Blood samples from 60 healthy volunteers were also obtained as controls. Circulating endothelial cells were measured by an immunomagnetic technique and immunofluorescence microscopy. Phosphatidylserine-positive microparticles were evaluated by flow cytometry. Microparticle-mediated procoagulant activity was measured by the endogen thrombin generation assay. Results: pre- and posttreatment levels of markers were higher in patients than in controls (p<0.0001). Elevated levels of microparticles were associated with longer survival. Elevated pretreatment levels of circulating endothelial cells were associated with shorter survival.

Conclusions/Significance

Circulating levels of microparticles and circulating endothelial cells correlate with prognosis, and could be useful as prognostic markers in patients with advanced non-small cell lung cancer.

Levels of a subpopulation of platelets, but not circulating endothelial cells, predict early treatment failure in prostate cancer patients after prostatectomy

Background:

Angiogenesis is one of the hallmarks of cancer driving tumour growth and ultimately metastasis. Circulating endothelial cells (CECs) and circulating endothelial progenitor (CEPs) cells have been reported as candidate surrogate markers for tumour vascularisation. Our aim was to investigate the potential use of these circulating cells levels as predictors of prostate cancer treatment failure and metastasis.

Methods:

We examined the levels of CD31⁺CD45⁻ cells (CECs) and CD31⁺CD45⁻CD117⁺ (CEPs) in s.c. and orthotopic models of human prostate cancers and correlated measurements with tumour size, volume and microvessel density (MVD). We then performed a prospective cohort study in 164 men with localised prostate cancer undergoing prostatectomy. The CD31⁺CD45⁻, CD31⁺CD45⁻CD146⁺ (CECs) and CD31⁺CD45^intermediateCD133⁺ (CEPs) populations were quantified and subsequently enriched for further characterisation.

Results:

In preclinical models, levels of CD31⁺CD45⁻ cells, but not CEPs, were significantly elevated in tumour-bearing mice and correlated with tumour size, volume and MVD. In our human prospective cohort study, the levels of CD31⁺CD45⁻ cells were significantly higher in men who experienced treatment failure within the first year, and on logistic regression analysis were an independent predictor of treatment failure, whereas neither levels of CECs or CEPs had any prognostic utility. Characterisation of the isolated CD31⁺CD45⁻ cell population revealed an essentially homogenous population of large, immature platelets representing <0.1% of circulating platelets.

Conclusion:

Elevated levels of a distinct subpopulation of circulating platelets were an independent predictor for early biochemical recurrence in prostate cancer patients within the first year from prostatectomy.

The role of targeted therapy and biomarkers in breast cancer treatment

Breast cancer is the most prevalent life-threatening cancer in women and the second leading cause of cancer associated deaths. Consequently, optimizing breast cancer therapy to increase cure rates in early stage disease and improve life expectancy and palliation for patients with metastasis is a critical need and major area of research in medical oncology. This article focuses on the development of personalized therapy in breast cancer though the use of targeted therapies and their associated biomarkers. Topics reviewed include the historic advances in targeting the HER2 receptor and the current avenues being studied to circumvent resistance; new developments in the management of triple negative and metastatic breast cancer; and the challenges and pitfalls associated with targeting angiogenesis. Using these as examples, many of the innovations and challenges in the treatment of women with breast cancer are explored.

Anti-angiogenic therapy: concept to clinic

It has been 40 years since Folkman hypothesized the use of anti-angiogenic therapy as a strategy in the treatment of cancer. Since then, vascular endothelial growth factor (VEGF) has been identified as the most potent cytokine to induce angiogenesis and drugs targeting VEGF, principally the humanized monoclonal antibody bevacizumab and the tyrosine kinase inhibitors sunitinib and sorafenib, have proven therapeutic benefit. The initial high expectations of tumor vascular targeting agents, however, have yet to be fulfilled. In unselected patient populations, the benefits of these agents is often marginal, they cause harmful side effects, and drug resistance is quickly established. Biomarkers to identify patients suitable for anti-angiogenic therapy will be key to the future development of these drugs.

Discrimination between circulating endothelial cells and blood cell populations with overlapping phenotype reveals distinct regulation and predictive potential in cancer therapy

BACKGROUND

Circulating endothelial cells (CECs) have been proposed to predict patient response to antiangiogenic cancer therapy. However, contradictory reports and inconsistency in the phenotypic identification of CECs have led us to compare three cell populations with partially overlapping phenotype in cancer patients receiving chemotherapy and the antiangiogenic agent bevacizumab.

METHODS

Patients (n = 20) with locally advanced pancreatic cancer were monitored during 16 weeks of neoadjuvant treatment with gemcitabine and bevacizumab. Detection of circulating cell populations was based on the marker combination CD45, CD31, and CD146; levels of viable and dead (7-aminoactinomycin D-positive) cells were evaluated by flow cytometry in 2-week intervals.

RESULTS

We were able to discriminate and concomitantly monitor three cell populations elevated in cancer patients. Whereas CECs were defined as CD45(-) CD31(+) CD146(+), the distinct populations of CD45(-) CD31(-) CD146(+) and CD45(-) CD31(high) CD146(-) cells were partly positive for CD3 and CD41, respectively. CECs and CD45(-) CD31(-) CD146(+) cells increased during therapy; the rise in dead cells was positively correlated with patient response or survival. Conversely, CD45(-) CD31(high) CD146(-) cells decreased in neoadjuvant treatment. A highly significant correlation was established for improved patient response and a minor decrease in viable cell counts.

CONCLUSIONS

Flow cytometric CEC analysis based on CD45, CD31, and CD146 requires careful discrimination between blood cell populations with overlapping phenotype showing hallmarks of activated T cells and large platelets. However, these three cell populations show distinct regulation during cancer therapy, and their concomitant analysis may offer extended prognostic and predictive information.

Circulating endothelial cells and their apoptotic fraction are mutually independent predictive biomarkers in Bevacizumab-based treatment for advanced colorectal cancer

BACKGROUND

Bevacizumab has shown consistent clinical efficacy in metastatic colorectal cancer (mCRC), but some patients respond better than others. Thus, it is crucial to identify biomarkers that permit the recognition of potentially responsive subjects and to spare toxicity in those who are unlikely benefit from treatment.

METHODS

In 24 mCRC patients undergoing Bevacizumab-based first-line treatment, we assessed by multiparameter flow cytometry changes in circulating endothelial cell (CEC) number, their apoptotic fraction (APO-CEC) and their mutual relationship. Data were compared with those from a group of 21 healthy subjects.

RESULTS

CECs and APO-CECs were higher in patients versus controls (p = 0.01 and p > 0.05, respectively). The increase in CECs at the 3rd cycle in complete response (CR) patients was statistically significant (p = 0.048). A better progression-free survival was evidenced in patients that showed an increase in CECs at the 6th cycle (p = 0.009). Regarding the changes in CECs and APO-CECs, a strong correlation was evidenced, at baseline, both in the global population (0.002; r: 0.53) and in the CR subgroup (p: 0.02; r: 0.77). In the partial response + stable and progression disease (SD + PD) subgroup, this correlation was highly significant at the 6th cycle (p: 0.001; r: 0.83).

CONCLUSIONS

We confirmed the predictive role of an increase in CECs in mCRC patients treated with Bevacizumab-based therapy and showed that modifications in CECs and APO-CECs are independent factors. This underlines the relevance of a simultaneous quantitative and functional evaluation of these biomarkers in view of their possible diagnostic utility.

Circulating endothelial cells and circulating endothelial precursor cells in patients with osteosarcoma

BACKGROUND

Circulating endothelial cells (CECs) have been detected at increased numbers in patients with solid cancers. CECs have not been systematically evaluated in patients with osteosarcoma.

PROCEDURE

Patients 12 months to 30 years of age with newly diagnosed high-grade osteosarcoma were eligible for this prospective cohort study. Patients provided a single blood sample at study entry for CEC quantification by flow cytometry at a single reference laboratory. CECs were defined as CD146+, CD31+, CD45-, and CD133-. CEC progenitor cells (CEPs) were defined as CD146+, CD31+, CD45-, and CD133+.

RESULTS

Eighteen patients enrolled (11 males; median age 16 years; range 5-21 years). CEC counts did not differ between patients with osteosarcoma compared to seven pediatric healthy controls (median 645 cells/ml, range 60-5,320 cells/ml vs. 1,670 cells/ml, range 330-4,700 cells/ml, respectively; P = 0.12). CEP counts did not differ between patients compared to controls (median 126 cells/ml, range 0-5,320 cells/ml vs. median 260 cells/ml, range 0-10,670 cells/ml, respectively; P = 0.69). CEC and CEP counts did not correlate with metastatic status, tumor size, or histologic response to neoadjuvant chemotherapy.

CONCLUSIONS

CEC and CEP levels are not increased in patients with osteosarcoma compared to healthy controls. CECs and CEPs do not correlate with clinical features of osteosarcoma. Alternative novel markers of disease burden and response are needed in this disease.

Pilot clinical trial of type 1 dendritic cells loaded with autologous tumor lysates combined with GM-CSF, pegylated IFN, and cyclophosphamide for metastatic cancer patients

Twenty-four patients with metastatic cancer received two cycles of four daily immunizations with monocyte-derived dendritic cells (DC). DC were incubated with preheated autologous tumor lysate and subsequently with IFN-α, TNF-α, and polyinosinic:polycytidylic acid to attain type 1 maturation. One DC dose was delivered intranodally, under ultrasound control, and the rest intradermally in the opposite thigh. Cyclophosphamide (day -7), GM-CSF (days 1-4), and pegIFN alpha-2a (days 1 and 8) completed each treatment cycle. Pretreatment with cyclophosphamide decreased regulatory T cells to levels observed in healthy subjects both in terms of percentage and in absolute counts in peripheral blood. Treatment induced sustained elevations of IL-12 in serum that correlated with the output of IL-12p70 from cultured DC from each individual. NK activity in peripheral blood was increased and also correlated with the serum concentration of IL-12p70 in each patient. Circulating endothelial cells decreased in 17 of 18 patients, and circulating tumor cells markedly dropped in 6 of 19 cases. IFN-γ-ELISPOT responses to DC plus tumor lysate were observed in 4 of 11 evaluated cases. Tracing DC migration with [(111)In] scintigraphy showed that intranodal injections reached deeper lymphatic chains in 61% of patients, whereas with intradermal injections a small fraction of injected DC was almost constantly shown to reach draining inguinal lymph nodes. Five patients experienced disease stabilization, but no objective responses were documented. This combinatorial immunotherapy strategy is safe and feasible, and its immunobiological effects suggest potential activity in patients with minimal residual disease. A randomized trial exploring this hypothesis is currently ongoing.

Molecular predictors of response to antiangiogenesis therapies

Angiogenesis is a crucial component of tumor growth and metastasis. Targeting the vascular endothelial growth factor pathway represents therapeutic potentials for treating cancer. To date, 3 Food and Drug Administration-approved agents targeting angiogenesis have been developed, bevacizumab, sunitinib, and sorafenib. However, no validated biomarkers are available to identify those patients who are likely to benefit from antiangiogenesis therapy. Molecular biomarker research in antiangiogenesis inhibition is an actively growing field. Although current data are extremely promising, it is still uncertain which biomarker(s) can reliably predict their efficacy. With increasing numbers of inhibitors being developed, the need for biomarkers is more critical than ever. This review will focus on translational research that strives to identify molecular biomarkers (tissue, circulating and genomic) for approved antiangiogenesis therapies that can indicate benefit, resistance, and toxicity.

Circulating endothelial and endothelial progenitor cells in non-small-cell lung cancer

New treatments have recently been introduced for treating non-small-cell lung cancer. Chemotherapeutic agents, such as pemetrexed, and targeted therapies, such as bevacizumab, erlotinib or gefitinib, have extended treatment options for selected histological subgroups. Antiangiogenic treatments, either associated with conventional chemotherapeutic drugs or given alone as maintenance therapy, constitute an active clinical research field. However, not all lung cancer patients benefit from antiangiogenic compounds. Moreover, tumour response assessment is often difficult when using these drugs, since targeted therapies generally do not cause rapid and measurable tumour shrinkage but, rather, long stabilisations and slight density changes on imaging tests. The finding of clinical or biological factors that might identify patients who will better benefit from these treatments, as well as identifying surrogate markers of tumour response and prognosis, is an issue of great interest. In that sense, different research lines have investigated the epidermal growth factor receptor (EGFR) and the vascular endothelial growth factor receptor (VEGFR) pathways. Circulating endothelial (CECs) and endothelial progenitor cells (CEPCs) are of prognostic value in different types of cancers, and relevant data are published about their potential usefulness as predictors of response to chemotherapy and antiangiogenic treatments. In this review, we discuss the data available on the role of CECs and CEPCs as prognostic factors and as surrogate markers of treatment response in non-small-cell lung cancer.

Human endothelial stem/progenitor cells, angiogenic factors and vascular repair

Neovascularization or new blood vessel formation is of utmost importance not only for tissue and organ development and for tissue repair and regeneration, but also for pathological processes, such as tumour development. Despite this, the endothelial lineage, its origin, and the regulation of endothelial development and function either intrinsically from stem cells or extrinsically by proangiogenic supporting cells and other elements within local and specific microenvironmental niches are still not fully understood. There can be no doubt that for most tissues and organs, revascularization represents the holy grail for tissue repair, with autologous endothelial stem/progenitor cells, their proangiogenic counterparts and the products of these cells all being attractive targets for therapeutic intervention. Historically, a great deal of controversy has surrounded the identification and origin of cells and factors that contribute to revascularization, the use of such cells or their products as biomarkers to predict and monitor tissue damage and repair or tumour progression and therapeutic responses, and indeed their efficacy in revascularizing and repairing damaged tissues. Here, we will review the role of endothelial progenitor cells and of supporting proangiogenic cells and their products, principally in humans, as diagnostic and therapeutic agents for wound repair and tissue regeneration.