Levels of circulating CD45(dim)CD34(+)VEGFR2(+) progenitor cells correlate with outcome in metastatic renal cell carcinoma patients treated with tyrosine kinase inhibitors. Br J Cancer. 2011;104:1144-1150. [PMID: 21386843 PMCID: PMC3068506 DOI: 10.1038/bjc.2011.72]

Circulating Biomarkers in Patients With Locally Advanced or Metastatic Renal Cell Carcinoma Treated With Everolimus in the Pre-nephrectomy Setting

Many drugs are available in renal cell carcinoma (RCC), yet clinicians are still looking for predictive biomarkers of disease recurrence or progression supporting more personalised treatments. An assessment of circulating biomarkers over time was carried out in this French, open-label, single-arm, multicentre trial conducted in 25 patients with either locally advanced (n = 14) or metastatic RCC (n = 11) who received everolimus (10 mg daily) for 6 weeks prior to nephrectomy (NEORAD, NCT01715935). Circulating biomarkers, including circulating tumour cells, haematopoietic and endothelial cells, plasma angiogenesis and inflammatory markers were quantified at baseline, upon everolimus and post-nephrectomy. We assessed tumour burden, objective response rate upon RECIST1.1, disease-free survival (DFS) and progression-free survival (PFS). The correlation between circulating biomarkers was evaluated with multiple factor analysis and biomarker association with DFS/PFS by Cox regression. No objective response rate was obtained before nephrectomy. Upon everolimus, neutrophils, platelets and sVEGFR2 significantly decreased. We did not find any association between circulating biomarkers and DFS/PFS, but patients with the highest tumour burden at baseline had significantly higher plasma levels of interleukin-6, an inflammatory circulating biomarker, and lower levels of sVEGFR2, related to angiogenesis. Further understanding of the link between these circulating biomarkers could help to optimise drug combinations in RCC.

Renal Carcinoma and Angiogenesis: Therapeutic Target and Biomarkers of Response in Current Therapies

Due to the aberrant hypervascularization and the high immune infiltration of renal tumours, current therapeutic regimens of renal cell carcinoma (RCC) target angiogenic or immunosuppressive pathways or both. Tumour angiogenesis plays an essential role in tumour growth and immunosuppression. Indeed, the aberrant vasculature promotes hypoxia and can also exert immunosuppressive functions. In addition, pro-angiogenic factors, including VEGF-A, have an immunosuppressive action on immune cells. Despite the progress of treatments in RCC, there are still non responders or acquired resistance. Currently, no biomarkers are used in clinical practice to guide the choice between the different available treatments. Considering the role of angiogenesis in RCC, angiogenesis-related markers are interesting candidates. They have been studied in the response to antiangiogenic drugs (AA) and show interest in predicting the response. They have been less studied in immunotherapy alone or combined with AA. In this review, we will discuss the role of angiogenesis in tumour growth and immune escape and the place of angiogenesis-targeted biomarkers to predict response to current therapies in RCC.

Dynamics of endothelial progenitor cells in patients with advanced hepatocellular carcinoma

BACKGROUND AND AIMS

Circulating endothelial progenitor cells (EPC) predict tumor vascularization and disease progression, but limited information is available on their dynamics in hepatocellular carcinoma (HCC) undergoing systemic treatment.

METHODS

We prospectively analyzed different populations of EPC in 16 patients with advanced HCC receiving sorafenib. Patients were studied before therapy (T0, n = 16) and after two (T2, n = 12) and eight weeks (T8, n = 8), using high-performance flow-cytometry. The tumor response at T8 was categorized as progressive disease (PD) or clinical benefit (CB, all other responses).

RESULTS

At T0, higher levels of CD34⁺CD133⁺KDR⁺ and CD34⁺KDR⁺ were observed in patients with alpha-fetoprotein ≥400 ng/ml or non-viral liver disease, whereas CD34⁺CD133⁺KDR⁺ cells were virtually absent in patients with vascular invasion. CD34⁺KDR⁺ and CD34⁺CD133⁺KDR⁺ were directly correlated with platelet count. Frequencies of all populations of EPC declined in patients receiving sorafenib. Levels of CD34⁺CD133⁺ were higher at T0 in patients with CB compared to patients with PD. In patients belonging to the CB group CD34⁺KDR⁺ cells at T0 were directly correlated to platelet count.

CONCLUSION

In patients with advanced HCC, EPC are directly correlated with platelet count, suggesting a common activation of selected bone marrow pathways. Levels of a CD34⁺KDR⁺ are higher at baseline in patients responding to sorafenib.

The Potential Mechanism Behind Native and Therapeutic Collaterals in Moyamoya

Background and Purpose

To explore the genetic basis and molecular mechanism of native arteriogenesis and therapeutic synangiosis in moyamoya disease (MMD).

Methods

An angiography-based study using patients from a prospective trial of encephaloduroarteriosynangiosis (EDAS) surgery was performed. The spontaneous collaterals grades were evaluated according to the system described by a new grading system. Blood samples were collected from all the recruited patients before EDAS and during the second hospitalization 3 months post-EDAS. We performed Boolean analysis using a combination of specific cell surface markers of CD34^briCD133⁺CD45^dimKDR⁺. Genotyping of p.R4810K was also performed. The correlation of age, sex, initial symptoms at diagnosis, collateral grade, Suzuki stages, the RNF213 genotype, time to peak (TTP), and endothelial progenitor cell (EPC) count with good collateral circulation was evaluated.

Results

Eighty-five patients with MMD were included in this study. The mutation rate of RNF213 p.R4810K in our study was 25.9% (22/85). The heterozygous mutations were occurred significantly more frequently in the cases that were presented with infarction, worse neurological status, severe posterior cerebral artery (PCA) stenosis, and longer TTP delay. Further, the heterozygous mutations occurred significantly more frequently in the poor collateral stage group. Lower grades were significantly correlated with severe ischemia symptoms, worse neurological status, and a longer TTP delay. The post-operative angiographic findings showed that a good Matsushima grade was correlated with heterozygous mutations, a lower collateral stage, and a longer TTP delay. The CD34^briCD133⁺CD45^dimKDR⁺ cell count in patients 3 months post-EDAS was significantly higher as compared to the count before EDAS in the good Matsushima grade group. However, this change was not observed in the poor Matsushima grade group.

Conclusions

These data imply that mutations of RNF213 p.R4810K affect the establishment of spontaneous collateral circulation, and EPCs are involved in the process of formation of new EDAS collaterals.

Identification of a Novel Glycolysis-Related Gene Signature Correlates With the Prognosis and Therapeutic Responses in Patients With Clear Cell Renal Cell Carcinoma

Background

Accumulating evidences indicate significant alterations in the aerobic glycolysis in clear cell renal cell carcinoma (ccRCC). We aim to develop and validate a glycolysis-related genes signature for predicting the clinical outcomes of patients with ccRCC.

Methods

mRNA expression profiling of ccRCC was obtained from The Cancer Genome Atlas database. Univariate Cox regression analysis and lasso Cox regression model were performed to identify and construct the prognostic gene signature. The protein expression levels of the core genes were obtained from the Human Protein Atlas database. We used four external independent data sets to verify the predictive power of the model for prognosis, tyrosine kinase inhibitor (TKI) therapy, and immunotherapy responses, respectively. Finally, we explored the potential mechanism of this signature through gene set enrichment analysis (GSEA).

Results

Through the GSEA, glycolysis-related gene sets were significantly different between ccRCC tissues and normal tissues. Next, we identified and constructed a seven-mRNA signature (GALM, TGFA, RBCK1, CD44, HK3, KIF20A, and IDUA), which was significantly correlated with worse survival outcome and was an independent prognostic indicator for ccRCC patients. Furthermore, the expression levels of hub genes were validated based on the Human Protein Atlas databases. More importantly, the model can predict patients’ response to TKI therapy and immunotherapy. These findings were successfully validated in the external independent ccRCC cohorts. The mechanism exploration showed that the model may influence the prognosis by influencing tumor proliferation, base mismatch repair system and immune status of patients.

Conclusions

Our study has built up a robust glycolysis-based molecular signature that predicts the prognosis and TKI therapy and immunotherapy responses of patients with ccRCC with high accuracy, which might provide important guidance for clinical assessment. Also, clinical investigations in large ccRCC cohorts are greatly needed to validate our findings.

Prospective Translational Study Investigating Molecular PrEdictors of Resistance to First-Line PazopanIb in Metastatic reNal CEll Carcinoma (PIPELINE Study)

OBJECTIVES

Despite the initial clinical benefit, resistance to antiangiogenic therapies develops through the activation of alternative pathways. We measured plasma levels of circulating angiogenic factors to explore their predictive role in metastatic renal cell carcinoma (mRCC) patients treated with pazopanib.

MATERIALS AND METHODS

mRCC patients receiving first-line pazopanib were prospectively enrolled. The levels of circulating interleuchine (IL)-6, IL-8, stromal derived factor-1, vascular endothelial growth factor-A, hepatocyte growth factor (HGF), osteopontin, and E-selectin were quantified at baseline and every 4 weeks until disease progression (PD). Patients were dichotomized into "low" and "high" subgroups by a cutoff point defined by the respective median circulating angiogenic factor (CAF) value at baseline. Then, association with the objective response was determined. Changes in CAF levels between baseline and PD were also compared.

RESULTS

Among 25 patients included in the final data set, 6 patients were still on treatment. As best response, 12 patients presented a partial response (48%), 9 showed stable disease, and 4 showed PD. The median follow-up was 31.9 months. The median progression-free survival was 14.8 months. Low baseline levels of IL-6, IL-8, HGF, and osteopontin were found to be significantly associated with objective response. In addition, patients with low baseline levels of HGF showed longer progression-free survival and overall survival, whereas patients with low baseline levels of IL-8 showed longer overall survival. Among patients experiencing PD, the median plasma levels of stromal derived factor-1 and vascular endothelial growth factor-A were significantly higher compared with the baseline (P=0.01; P=0.011). Conversely, the median levels of E-selectin were significantly lower compared with the baseline (P=0.017).

CONCLUSION

Changes in levels of selected CAFs were associated with response/resistance to pazopanib in mRCC patients.

Targeting the Tumor Microenvironment in Renal Cell Cancer Biology and Therapy

Renal cell cancer (RCC) is a highly vascularized and immunogenic tumor type. The inhibition of vessel formation by anti-angiogenic therapies, as well as the stimulation of the immune system by immunotherapy has revolutionized the therapeutic landscape of RCC in recent years. Nevertheless, both therapies are associated with therapy resistance due to a highly dynamic, adaptive and heterogeneous tumor microenvironment (TME). The aim of this short review article is to provide an overview of the components of the RCC TME as well as to discuss their contribution to disease progression. In addition, we report on preclinical and clinical findings and how the different TME components can be modulated to impede treatment progression as well as to overcome therapy resistance to anti-angiogenic or immunomodulating therapy concepts. Furthermore, we discuss the predictive and prognostic role of the TME in RCC therapy. We also report on the concept of combinational targeting of anti-angiogenic therapies and immune checkpoint inhibitor therapy, also including the latest results of clinical studies discussed at recent oncological meetings. Finally, promising new therapeutic targets within the TME are mentioned.

Sunitinib Prior to Planned Nephrectomy in Metastatic Renal Cell Carcinoma: Angiogenesis Biomarkers Predict Clinical Outcome in the Prospective Phase II PREINSUT Trial

Purpose: The PREINSUT study characterized factors predictive of response to sunitinib given before planned nephrectomy in patients with metastatic renal cell carcinoma (mRCC).Patients and Methods: This French multicenter, prospective, open-label, phase II trial (NCT00930345) included treatment-naïve patients with clear-cell mRCC. Patients received two cycles of sunitinib before nephrectomy. The primary objective was to evaluate the potential of circulating angiogenesis-related biomarkers measured before and on treatment for identifying responders based on primary renal tumor (PRT) size change. Secondary objectives were to evaluate the ability of biomarkers to predict progression-free survival (PFS) and overall survival (OS).Results: Thirty-two patients were enrolled. The median PFS was 4.5 months, and the median OS was 12.4 months. OS was significantly longer in responding patients (28.8 vs. 11.1 months; P = 0.03). Of 27 patients evaluable for PRT response, nine (33.3%) had a ≥10% decrease in PRT size. Baseline biomarkers significantly associated with outcome were endothelial progenitor cells (PRT response); vascular endothelial growth factor (VEGF)-A, stromal cell-derived factor-1 (SDF-1), soluble VEGF receptors (sVEGFR)1 and 2 (PFS); and SDF-1 and sVEGFR1 (OS). During treatment, changes in biomarkers associated with outcome were SDF-1 and platelet-derived growth factor (PDGF)-BB (PRT response), sVEGFR2 (PFS), and SDF-1 and sVEGFR1 (OS). There was no correlation between plasma sunitinib or its active metabolite steady-state trough concentrations and clinical outcome.Conclusions: Angiogenesis-related parameters that could reflect hypoxia seem to be associated with worse outcome in mRCC. As blood biomarkers are not subjected to tumor heterogeneity and allow longitudinal follow-up, circulating angiogenesis profile has a promising place in antiangiogenic therapy guidance. Clin Cancer Res; 24(22); 5534-42. ©2018 AACR.

Prognostic and predictive value of VHL gene alteration in renal cell carcinoma: a meta-analysis and review

The von Hippel-Lindau (VHL) gene is often inactivated in sporadic renal cell carcinoma (RCC) by mutation or promoter hypermethylation. The prognostic or predictive value of VHL gene alteration is not well established. We conducted this meta-analysis to evaluate the association between the VHL alteration and clinical outcomes in patients with RCC. We searched PUBMED, MEDLINE and EMBASE for articles including following terms in their titles, abstracts, or keywords: 'kidney or renal', 'carcinoma or cancer or neoplasm or malignancy', 'von Hippel-Lindau or VHL', 'alteration or mutation or methylation', and 'prognostic or predictive'. There were six studies fulfilling inclusion criteria and a total of 633 patients with clear cell RCC were included in the study: 244 patients who received anti-vascular endothelial growth factor (VEGF) therapy in the predictive value analysis and 419 in the prognostic value analysis. Out of 663 patients, 410 (61.8%) had VHL alteration. The meta-analysis showed no association between the VHL gene alteration and overall response rate (relative risk = 1.47 [95% CI, 0.81-2.67], P = 0.20) or progression free survival (hazard ratio = 1.02 [95% CI, 0.72-1.44], P = 0.91) in patients with RCC who received VEGF-targeted therapy. There was also no correlation between the VHL alteration and overall survival (HR = 0.80 [95% CI, 0.56-1.14], P = 0.21). In conclusion, this meta-analysis indicates that VHL gene alteration has no prognostic or predictive value in patients with clear cell RCC.

Endothelial progenitor cells: Exploring the pleiotropic effects of statins

Statins have become a cornerstone of risk modification for ischaemic heart disease patients. A number of studies have shown that they are effective and safe. However studies have observed an early benefit in terms of a reduction in recurrent infarct and or death after a myocardial infarction, prior to any significant change in lipid profile. Therefore, pleiotropic mechanisms, other than lowering lipid profile alone, must account for this effect. One such proposed pleiotropic mechanism is the ability of statins to augment both number and function of endothelial progenitor cells. The ability to augment repair and maintenance of a functioning endothelium may have profound beneficial effect on vascular repair and potentially a positive impact on clinical outcomes in patients with cardiovascular disease. The following literature review will discuss issues surrounding endothelial progenitor cell (EPC) identification, role in vascular repair, factors affecting EPC numbers, the role of statins in current medical practice and their effects on EPC number.

A Prospective Observational Study for Assessment and Outcome Association of Circulating Endothelial Cells in Clear Cell Renal Cell Carcinoma Patients Who Show Initial Benefit from First-line Treatment. The CIRCLES (CIRCuLating Endothelial cellS) Study (SOGUG-CEC-2011-01)

BACKGROUND

Markers able to predict the response to antiangiogenics in metastatic clear cell renal cell carcinoma (ccRCC) are not available. The development of new treatment options like immunotherapy are reaching the clinic; therefore, predictors of benefit from these different available treatments are increasingly needed.

OBJECTIVE

In this study, we prospectively assessed the association of circulating endothelial cells (CECs) in peripheral blood with long-term benefit from first-line treatment in ccRCC.

DESIGN, SETTING, AND PARTICIPANTS

A prospective observational study was designed involving 13 institutions of the Spanish Oncology Genitourinary Group. Adult patients diagnosed with advanced ccRCC who had achieved response or disease stabilization after 3 mo on first-line therapy were eligible.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

CECs were isolated from peripheral blood, captured with ferrofluids coated with monoclonal antibodies directed against the CD146 antigen, and assessed centrally with an automated standardized system. CECs were defined as 4',6-diamidino-2-phenylindole+, CD105+, and CD45-. Blood samples were systematically taken every 6 wk for 15 mo or until tumor progression, whichever occurred first. Clinical data were externally monitored at all centers.

RESULTS AND LIMITATIONS

From August 9, 2011, to January 17, 2013, 75 patients were enrolled in the study. Patients with baseline CECs above the median showed a significantly longer progression-free survival than those with low CECs (22.2 mo vs 12.2 mo) with a hazard ratio of 2.5 (95% confidence interval: 1.2-5.3, p=0.016). There was no difference between CEC levels at baseline and at tumor progression (medians of 50 CECs/4ml and 52 CECs/4ml, respectively).

CONCLUSIONS

Under antiangiogenic treatment, the detection of higher CEC levels is associated with clinical benefit in terms of progression-free survival in ccRCC.

PATIENT SUMMARY

Antiangiogenics are the cornerstone of treatment in kidney cancer. Since they target endothelial rather than tumor cells, we studied the correlation between levels of circulating endothelial cells in peripheral blood and long-term benefit in patients on antiangiogenic therapy. Higher levels were associated with long-term benefit, suggesting that this determination could help to separate best responders from those who could require a more intensive approach.

Endothelial progenitor cell number and ERK phosphorylation serve as predictive and prognostic biomarkers in advanced hepatocellular carcinoma patients treated with sorafenib

Sorafenib is an oral anti-angiogenic multi-kinase inhibitor used for systemic therapy in patients with advanced hepatocellular carcinoma (HCC) who are not suitable candidates for surgery or liver transplantation. An earlier study conducted with HCC tumor tissue suggested that ERK phosphorylation (pERK), a downstream target of sorafenib, may serve as a potential biomarker for therapeutic efficacy of sorafenib. However, no study thus far has utilized a minimal invasive procedure to predict HCC patient responsiveness to sorafenib. We evaluated the biomarker utility of circulating endothelial progenitor cells (EPCs) frequency and intracellular pERK levels in EPCs in peripheral blood obtained pre- and post-sorafenib therapy or after transarterial chemoembolistaion (TACE). A statistically significant reduction in the level of ERK phosphorylation and in the absolute number of EPCs was detected following in vivo sorafenib treatment (p < 0 .01 for both). In contrast, the decrease in the level of ERK phosphorylation and EPC number was either marginally significant or insignificant in patients treated with TACE (p = 0.05 and 0.06, respectively). In vitro sorafenib treatment of pre- and post-samples from the same patient cohort inhibited ERK phosphorylation levels in EPCs and decreased the number of EPCs at all doses tested (p = 0.01). Our findings support that the evaluation of both the circulating EPC frequency and the level of ERK phosphorylation in EPCs may serve as potential non-invasive biomarkers of sorafenib efficacy, both as predictor of treatment outcome and efficacy during drug treatment.

Balancing efficacy of and host immune responses to cancer therapy: the yin and yang effects

Local and systemic treatments for cancer include surgery, radiation, chemotherapy, hormonal therapy, molecularly targeted therapies, antiangiogenic therapy, and immunotherapy. Many of these therapies can be curative in patients with early stage disease, but much less frequently is this the case when they are used to treat advanced-stage metastatic disease. In the latter setting, innate and/or acquired resistance are among the reasons for reduced responsiveness or nonresponsiveness to therapy, or for tumour relapse after an initial response. Most studies of resistance or reduced responsiveness focus on 'driver' genetic (or epigenetic) changes in the tumour-cell population. Several studies have highlighted the contribution of therapy-induced physiological changes in host tissues and cells that can reduce or even nullify the desired antitumour effects of therapy. These unwanted host effects can promote tumour-cell proliferation (repopulation) and even malignant aggressiveness. These effects occur as a result of systemic release of numerous cytokines, and mobilization of various host accessory cells, which can invade the treated tumour microenvironment. In short, the desired tumour-targeting effects of therapy (the 'yin') can be offset by a reactive host response (the 'yang'); proactively preventing or actively suppressing the latter represents a possible new approach to improving the efficacy of both local and systemic cancer therapies.

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.

Preoperative biomarkers of tumour vascularity are elevated in patients with glioblastoma multiforme

We investigated the correlation between the circulating and imaging biomarkers of tumour vascularity, and examined whether they are prognostic of outcomes in patients with glioblastoma multiforme (GBM). Despite the increasing use of anti-angiogenic agents within neuro-oncology, there are still no validated biomarkers to monitor for a treatment response or relapse. The pre- and postoperative circulating endothelial cell (CEC) and progenitor cell (CEP) levels were assessed. Preoperative perfusion-weighted MRI (PWI) was also performed, and the relative cerebral blood volume (rCBV) histogram statistics of the contrast-enhancing tumour were analysed. A novel PWI parameter (rCBVload) was developed to estimate the total volume of perfused tumour vessels, and it was hypothesised that this parameter would correlate with CEC and CEP concentrations. In total, 24 GBM patients were included. The mean preoperative CEC concentration was significantly higher in GBM patients than the controls (p=0.019), and it then declined significantly postoperatively (p=0.009). The preoperative CEP levels were significantly correlated with the median tumour rCBV (Spearman rank-order coefficient=0.526; p=0.039). Neither CEC nor CEP was correlated with the total tumour vessel volume, as measured by rCBVload. None of the biomarkers that were investigated showed a significant correlation with progression-free or overall survival. We conclude that CEC are potentially useful biomarkers to monitor GBM patients during treatment. We found that CEC are increased in the presence of GBM, and that CEP levels appear to be proportional to tumour vascularity, as measured on PWI. However, in this study, none of the biomarkers of GBM vascularity were highly prognostic of patient outcomes.

Predictive biomarker candidates to delineate efficacy of antiangiogenic treatment in renal cell carcinoma

Antiangiogenic therapy is currently considered as the cornerstone of treatment in metastatic kidney cancer. A monoclonal antibody against the vascular endothelial growth factor (VEGF) and several tyrosine kinase inhibitors targeting the VEGF receptors demonstrated, 7 years ago, to deeply impact the outcome of this tumor and became a model of integration of molecular knowledge into clinical practice. Unfortunately, no further improvement in survival has been made and 20-25 % of cases remain primary refractory to these drugs, with an overall dismal prognosis. Since biomarker predictors of activity are lacking, their development could highly help in the process of making clinical decisions when choosing the best option for every patient or prompting the inclusion in clinical trials. This unmet medical need could become even more relevant if new immunotherapy confirms its initial promising results in this pathology. In this article, we provide an insight of current state of the art regarding the prediction of antiangiogenic efficacy in kidney cancer and propose new strategies for the implementation of such markers in clinical practice.

Pharmacogenomic biomarkers for personalized cancer treatment

Personalized medicine involves the selection of the safest and most effective pharmacological treatment based on the molecular characteristics of the patient. In the case of anticancer drugs, tumour cell alterations can have a great impact on drug activity and, in fact, most biomarkers predicting response originate from these cells. On the other hand, the risk of developing severe toxicity may be related to the genetic background of the patient. Thus, understanding the molecular characteristics of both the tumour and the patient, and establishing their relation with drug outcomes will be critical for the identification of predictive biomarkers and to provide the basis for individualized treatments. This is a complex scenario where multiple genes as well as pathophysiological and environmental factors are important; in addition, tumours exhibit large inter- and intraindividual variability in space and time. Against this background, the huge amounts of biological and genetic data generated by the high-throughput technologies will facilitate pharmacogenomic progress, suggest novel druggable molecules and support the design of future strategies aimed at disease control. Here, we will review the current challenges and opportunities for pharmacogenomic studies in oncology, as well as the clinically established biomarkers. Lung and renal cancer, two areas in which huge progress has been made in the last decade, will be used to illustrate advances in personalized cancer treatment; we will review EGFR mutation as the paradigm of targeted therapies in lung cancer, and discuss the dissection of lung cancer into clinically relevant molecular subsets and novel advances that suggest an important role of single nucleotide polymorphisms in the response to antiangiogenic agents, as well as the challenges that remain in these fields. Finally, we will present new approaches and future prospects for personalizing medicine in oncology.

Resistance to sunitinib in renal cell carcinoma: From molecular mechanisms to predictive markers and future perspectives

The introduction of agents that inhibit tumor angiogenesis by targeting vascular endothelial growth factor (VEGF) signaling has made a significant impact on the survival of patients with metastasized renal cell carcinoma (RCC). Sunitinib, a tyrosine kinase inhibitor of the VEGF receptor, has become the mainstay of treatment for these patients. Although treatment with sunitinib substantially improved patient outcome, the initial success is overshadowed by the occurrence of resistance. The mechanisms of resistance are poorly understood. Insight into the molecular mechanisms of resistance will help to better understand the biology of RCC and can ultimately aid the development of more effective therapies for patients with this infaust disease. In this review we comprehensively discuss molecular mechanisms of resistance to sunitinib and the involved biological processes, summarize potential biomarkers that predict response and resistance to treatment with sunitinib, and elaborate on future perspectives in the treatment of metastasized RCC.

Molecular marker for predicting treatment response in advanced renal cell carcinoma: does the promise fulfill clinical need?

Renal cell carcinoma (RCC) is largely diagnosed incidentally on imaging taken for unrelated reasons. The management of localized lesions is primarily extirpative with excellent results. Treatment of advanced RCC has evolved over recent years with the use of targeted therapies such as tyrosine kinase inhibitors, mammalian target of rapamycin inhibitors, and antibody-mediated therapies. The treatment response to these targeted therapies is highly variable, with no clear clinical method of identifying patients who will benefit from or not tolerate therapy. The field of molecular markers has evolved significantly in the last decade, with a multitude of markers identified that predict treatment response and drug toxicity. The following review critically evaluates those molecular markers that have been assessed for their utility in predicting treatment response in patients with advanced/metastatic renal cell carcinoma (mRCC). Identifying the ideal treatment for these patients will improve responses to therapy, minimize morbidity, and save significant healthcare dollars.

Identification and significance of mobilized endothelial progenitor cells in tumor neovascularization of renal cell carcinoma

Neovascularization is a key role of renal cell carcinoma (RCC) and the status of neovascularization in RCC is closely correlated with the tumor development and patient prognosis. Endothelial progenitor cells (EPCs) are considered as important building blocks for neovascularization. However, the role of mobilized EPCs in RCC remains unknown. In this study, the orthotopic RCC model was established to investigate the distribution, frequency, and significance of mobilized EPCs. We found that circulating endothelial progenitor cell (CEPC) levels and plasma angiogenic factors (vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1 (SDF-1) were higher in peripheral blood (PB) of the RCC than those in the normal group and positively correlated with each other. EPC levels in adjacent nonmalignant kidney tissue (AT) were significantly higher than those in tumor tissue (TT) and normal kidney tissue (NT), which were positively correlated with CEPC levels. VEGF, VEGF receptor-2 (Flk), and SDF-1 and its SDF-1 receptor (CXCR4) expression in AT was significantly higher than that in TT and NT. Levels of these angiogenic factors in AT were positively correlated with those in PB. Mean microvessel density (MVD) was higher in AT than in TT, and that in TT was slightly lower than that in NT. Our findings propose that mobilized EPCs play an important role in RCC neovascularization. EPCs in PB and AT can be used as a biomarker for predicting RCC progression.

Active angiogenesis in metastatic renal cell carcinoma predicts clinical benefit to sunitinib-based therapy

Background:

Sunitinib represents a widely used therapy for metastatic renal cell carcinoma patients. Even so, there is a group of patients who show toxicity without clinical benefit. In this work, we have analysed pivotal molecular targets involved in angiogenesis (vascular endothelial growth factor (VEGF)-A, VEGF receptor 2 (KDR), phosphorylated (p)KDR and microvascular density (MVD)) to test their potential value as predictive biomarkers of clinical benefit in sunitinib-treated renal cell carcinoma patients.

Methods:

Vascular endothelial growth factor-A, KDR and pKDR-Y1775 expression as well as CD31, for MVD visualisation, were determined by immunohistochemistry in 48 renal cell carcinoma patients, including 23 metastatic cases treated with sunitinib. Threshold was defined for each biomarker, and univariate and multivariate analyses for progression-free survival (PFS) and overall survival (OS) were carried out.

Results:

The HistoScore mean value obtained for VEGF-A was 121.6 (range, 10–300); for KDR 258.5 (range, 150–300); for pKDR-Y1775 10.8 (range, 0–65) and the mean value of CD31-positive structures for MVD visualisation was 49 (range, 10–126). Statistical differences for PFS (P=0.01) and OS (P=0.007) were observed for pKDR-Y1775 in sunitinib-treated patients. Importantly, pKDR-Y1775 expression remained significant after multivariate Cox analysis for PFS (P=0.01; HR: 5.35, 95% CI, 1.49–19.13) and for OS (P=0.02; HR: 5.13, 95% CI, 1.25–21.05).

Conclusions:

Our results suggest that the expression of phosphorylated (i.e., activated) KDR in tumour stroma might be used as predictive biomarker for the clinical outcome in renal cell carcinoma first-line sunitinib-treated patients.

A phase II open-label randomized multicenter trial of TSU-68 in combination with S-1 and oxaliplatin versus S-1 in combination with oxaliplatin in patients with metastatic colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the fourth leading cause of cancer-related deaths worldwide. The combination of oxaliplatin-based treatments (oxaliplatin plus infusional 5-fluorouracil and leucovorin [FOLFOX] or oxaliplatin plus capecitabine [CapeOX]) and bevacizumab is a standard chemotherapy regimen for metastatic CRC (mCRC). However, several clinical studies that tested S-1 plus oxaliplatin (SOX) indicate that SOX is also a treatment option for mCRC. TSU-68 is an oral compound that inhibits vascular endothelial growth factor receptor and platelet-derived growth factor receptor. The recommended dose of TSU-68 + SOX was previously determined in a phase I study of mCRC patients. The goal of this trial was to evaluate the efficacy of TSU-68 in combination with SOX.

METHODS

This open-label multicenter randomized phase II trial was performed in Korea. Treatment-naive mCRC patients with a performance status of 0 or 1 were randomized in a 1:1 ratio to receive either TSU-68 + SOX or SOX alone. The primary endpoint was progression-free survival (PFS).

RESULTS

A total of 105 patients (TSU-68 + SOX, 52 patients; SOX alone, 53 patients) were randomized. The median PFS was 7.0 months in the TSU-68 + SOX group (hazard ratio [HR], 1.057) and 7.2 months in the SOX group (p = 0.8401). The most frequent grade 3 and 4 adverse events were thrombocytopenia (9.6 % [TSU-68 + SOX] vs. 26.4 % [SOX]), neutropenia (13.5 % [TSU-68 + SOX] vs. 15.1 % [SOX]), and anemia (3.8 % [TSU-68 + SOX] vs. 13.2 % [SOX]). We observed a difference between the 2 groups for all grades of anemia (15.4 % [TSU-68 + SOX] vs. 32.1 % [SOX]), diarrhea (30.8 % [TSU-68 + SOX] vs. 47.2 % [SOX]), vomiting (50.0 % [TSU-68 + SOX] vs. 26.4 % [SOX]), and chromaturia (23.1 % [TSU-68 + SOX] vs. 0.0 % [SOX]). Analysis using a Cox proportional hazard model showed that baseline interleukin 6 (IL-6) levels were associated with a survival benefit of TSU-68 (p = 0.012).

CONCLUSION

TSU-68 + SOX had a favorable safety profile. However, TSU-68 did not have a synergistic effect on the efficacy of SOX. The baseline serum IL-6 level could be a prognostic factor for TSU-68 efficacy.

Renal carcinoma pharmacogenomics and predictors of response: Steps toward treatment individualization

Molecular knowledge has deeply affected the treatment and outcome of kidney cancer in recent years, and several therapeutic options have become available. However, there are no validated biomarkers to select the best drug for each patient. Already published studies and ongoing investigations could change this scenario in the near future. Regarding antiangiogenic drugs, several works on single nucleotide polymorphisms have achieved promising results, with some SNPs predicting resistance to sunitinib and pazopanib being validated. If more evidence is gained, it could prompt prospective studies exploring a molecularly driven selection of treatment. Another relevant line of investigation for antiangiogenic drugs is the cytokines and antiangiogenic factors. Different studies have found that cytokines and antiangiogenic factors are able to predict the outcome of patients treated with sunitinib, pazopanib, or sorafenib. Issues regarding the thresholds of normality and the best time for assessment are pending, but the communicated results are encouraging. Less evidence is available for mammalian target of rapamycin inhibitors but recent data support a key role of the phosphoinositide 3-kinase/Akt pathway in clear cell renal cell carcinoma and points toward poor response to angiogenic drugs when the pathway is activated. Whether modern phosphoinositide 3-kinase inhibitors could be the best option for these patients is a question that should be addressed. Additionally, a new class of immunomodulators, like anti-programmed death 1 drugs, has demonstrated to achieve long-lasting stabilizations even in some patients with no radiological response or early progression. This is a singular situation where the identification of reliable predictors of efficacy will be key in the development of these drugs in renal cell carcinoma. Finally, germline mutations of the c-Met gene have been proposed as the first predictor of response to targeted therapies in papillary renal cell carcinoma. As a conclusion, translational research will be a cornerstone to move a next step forward in kidney cancer.

A systematic review of predictive and prognostic biomarkers for VEGF-targeted therapy in renal cell carcinoma

BACKGROUND

Vascular endothelial growth factor (VEGF)-targeted therapy is the currently standard treatment for advanced and metastatic renal cell carcinoma (RCC). Multiple candidate predictive and prognostic biomarkers have been evaluated. We performed a systematic review and graded the available evidence on the biomarkers for VEGF-targeted therapy in RCC.

METHODS

We conducted an independent review of PubMed and ASCO databases up to August 2013. Studies were included if biomarkers obtained from metastatic clear-cell RCC patients treated with the FDA-approved VEGF-targeted therapy were assessed for their correlation with clinical outcomes. We graded the studies and determined the Level-of-evidence for each biomarker using a previously published framework.

RESULTS

A total of 50 articles were selected for this review. Seven studies assessed the predictive value of biomarkers using the archived specimens from randomized controlled trials. Five predictive biomarkers, such as VEGF, interleukin (IL)-6, hepatocyte growth factor (HGF), osteopontin, single nucleotide polymorphisms in IL-8, satisfied Level II evidence. IL-6 is the most corroborated predictive biomarker based on its consistent predictive value in two different trials. The prognostic value of biomarkers was assessed in 48 studies using the archived specimens from clinical trials, prospective and retrospective observational registries. Three biomarkers, including IL-8, HGF and osteopontin, satisfied Level I evidence for PFS.

CONCLUSION

Though several promising predictive biomarkers for VEGF-targeted therapy have been found, none of them has satisfied the determination of Level I evidence. A more focused development of biomarkers with prospective assessment in clinical trials and clear intent of use in clinical practice is needed.

Molecular markers to predict response to therapy

Currently approved treatments for metastatic renal cell carcinoma (RCC) include vascular endothelial growth factor (VEGF)-blocking agents, mammalian target of rapamycin (mTOR) inhibitors, and cytokine therapy. In the near future, we are likely to add immune checkpoint blocking agents to this list. As we develop treatment platforms around each therapeutic class, determining which drug is best for a particular patient becomes increasingly important. At this point, we do not have validated predictive biomarkers for patients with RCC. Here, we discuss the logistical challenges surrounding biomarker development, summarize the current crop of biomarker candidates, and explore potential avenues for the development of more effective predictive tools for patients with advanced RCC.

Resistance to tyrosine kinase inhibitors in clear cell renal cell carcinoma: from the patient's bed to molecular mechanisms

The introduction of anti-angiogenic drugs especially tyrosine kinase inhibitors (TKIs) was a breakthrough in the treatment of renal cell carcinoma (RCC). Although TKIs have significantly improved outcome in patients with metastatic disease, the majority still develop resistance over time. Because different combinations and sequences of TKIs are tested in clinical trials, resistance patterns and mechanisms underlying this phenomenon should be thoroughly investigated. From a clinical point of view, resistance occurs either as a primary phenomenon (intrinsic) or as a secondary phenomenon related to various escape/evasive mechanisms that the tumor develops in response to vascular endothelial growth factor (VEGF) inhibition. Intrinsic resistance is less common, and related to the primary redundancy of available angiogenic signals from the tumor, causing unresponsiveness to VEGF-targeted therapies. Acquired resistance in tumors is associated with activation of an angiogenic switch which leads to either upregulation of the existing VEGF pathway or recruitment of alternative factors responsible for tumor revascularization. Multiple mechanisms can be involved in different tumor settings that contribute both to evasive and intrinsic resistance, and current endeavor aims to identify these processes and assess their importance in clinical settings and design of pharmacological strategies that lead to enduring anti-angiogenic therapies.

Differential regulation of sunitinib targets predicts its tumor-type-specific effect on endothelial and/or tumor cell apoptosis

PURPOSE

Sunitinib is an inhibitor of tyrosine-kinase receptors, and no biomarker predictive of sunitinib response is available. The purpose of this preclinical study was to show whether sunitinib molecular targets could be used as biomarkers to assess tumor response to sunitinib in human cancer cell line xenografts of three different tumor types.

METHODS

Using mice xenografted with liver, breast and renal carcinoma cell lines, we sequentially analyzed the effect of 7-day sunitinib treatment on tumor and vascular compartments.

RESULTS

In all xenografts, microvessel damage occurred from Day 1. Tumor damage also occurred in liver, breast, but not in renal xenografts. Using specific human and mouse probes for genes encoding sunitinib targets, we showed a significant relation between apoptotic tumor cell numbers and human PDGFRΒ and RET mRNA expression in liver cancer and to human VEGFR2 expression in breast cancer xenografts. In contrast, in renal cancer xenografts, vascular effect evaluated by measuring endothelial cell apoptosis was related to mouse Vegfr1, Vegfr2 and Vegfa-164 expression.

CONCLUSION

This study identifies sunitinib vascular and tumor effects according to different tumor types and shows that sunitinib molecular targets used as biomarkers enable assessment of therapeutic response.

MicroRNA expression profiling of peripheral blood samples predicts resistance to first-line sunitinib in advanced renal cell carcinoma patients

Anti-angiogenic therapy benefits many patients with advanced renal cell carcinoma (RCC), but there is still a need for predictive markers that help in selecting the best therapy for individual patients. MicroRNAs (miRNAs) regulate cancer cell behavior and may be attractive biomarkers for prognosis and prediction of response. Forty-four patients with RCC were recruited into this observational prospective study conducted in nine Spanish institutions. Peripheral blood samples were taken before initiation of therapy and 14 days later in patients receiving first-line therapy with sunitinib for advanced RCC. miRNA expression in peripheral blood was assessed using microarrays and L2 boosting was applied to filtered miRNA expression data. Several models predicting poor and prolonged response to sunitinib were constructed and evaluated by binary logistic regression. Blood samples from 38 patients and 287 miRNAs were evaluated. Twenty-eight miRNAs of the 287 were related to poor response and 23 of the 287 were related to prolonged response to sunitinib treatment. Predictive models identified populations with differences in the established end points. In the poor response group, median time to progression was 3.5 months and the overall survival was 8.5, whereas in the prolonged response group these values were 24 and 29.5 months, respectively. Ontology analyses pointed out to cancer-related pathways, such angiogenesis and apoptosis. miRNA expression signatures, measured in peripheral blood, may stratify patients with advanced RCC according to their response to first-line therapy with sunitinib, improving diagnostic accuracy. After proper validation, these signatures could be used to tailor therapy in this setting.

The association of blood angioregulatory microRNA levels with circulating endothelial cells and angiogenic proteins in patients receiving dacarbazine and interferon

Background

Blood biomarkers are needed to monitor anti-angiogenic treatments for cancer. The association of blood levels of microRNAs (miRs) implicated in angiogenesis with circulating endothelial cells (CEC) and with angiogenic proteins was examined in patients administered drugs with anti-angiogenic activity.

Methods

Blood was collected from patients with uveal melanoma enrolled on an adjuvant therapy trial in which they were treated sequentially with dacarbazine and interferon-alfa-2b. Plasma levels of nine angioregulatory miRs, miR-16, 20a, 106a, 125b, 126, 146a, 155, 199a, and 221, were determined by quantitative real time polymerase chain reaction; CEC, by semi-automated immunomagnetic; and plasma angiogenic proteins, by enzyme linked immunosorbent assays.

Results

Levels of miR-199a were positively correlated and miR-106a negatively correlated with CEC pre-therapy. Decreases in miR-126 and miR-199a and increases in miR-16 and miR-106a were observed after interferon-alfa-2b, but not after dacarbazine. CEC also increased after treatment with interferon but not after treatment with dacarbazine. Levels of miRs did not correlate with levels of vascular endothelial growth factor, basic fibroblast growth factor, and interleukin-8. Angiogenic proteins also did not change significantly with treatment.

Conclusions

Blood levels of specific angioregulatory miRs are associated with CEC, and changes in specific angioregulatory miRs parallel increases in CEC after treatment with interferon-alfa-2b. Blood levels of specific angioregulatory miRs are not associated with levels of angiogenic proteins. miRs warrant further evaluation as blood biomarkers of angiogenesis.

Constitutional genetic variants as predictors of antiangiogenic therapy outcome in renal cell carcinoma

The development of specific angiogenesis inhibitors has drastically improved renal cancer treatment in recent years. Currently, four VEGF receptor inhibitors (sorafenib, sunitinib, pazopanib and axitinib), one anti-VEGF monoclonal antibody (bevacizumab) and two inhibitors of the mTOR pathway (temsirolimus and everolimus) have been approved to treat renal cell carcinoma (RCC), and several other molecules are under investigation. However, lack of response to antiangiogenic drugs and adverse drug reactions leading to treatment suspension are critical clinical problems that need to be solved. Because antiangiogenic drugs act on nonmalignant endothelial cells, the genetic background of the patient may play a crucial role determining the efficacy of these drugs. This article focuses on the identification of polymorphisms associated with antiangiogenic drugs outcome in RCC patients. It reviews and summarizes our current knowledge on this area and discusses future strategies to identify new biomarkers that could be used to personalize RCC management.

Identification of luminal breast cancers that establish a tumor-supportive macroenvironment defined by proangiogenic platelets and bone marrow-derived cells

Breast cancer recurrence rates vary following treatment, suggesting that tumor cells disseminate early from primary sites but remain indolent indefinitely before progressing to symptomatic disease. The reasons why some indolent disseminated tumors erupt into overt disease are unknown. We discovered a novel process by which certain luminal breast cancer (LBC) cells and patient tumor specimens (LBC "instigators") establish a systemic macroenvironment that supports outgrowth of otherwise-indolent disseminated tumors ("responders"). Instigating LBCs secrete cytokines that are absorbed by platelets, which are recruited to responding tumor sites where they aid vessel formation. Instigator-activated bone marrow cells enrich responding tumor cell expression of CD24, an adhesion molecule for platelets, and provide a source of VEGF receptor 2(+) tumor vessel cells. This cascade results in growth of responder adenocarcinomas and is abolished when platelet activation is inhibited by aspirin. These findings highlight the macroenvironment as an important component of disease progression that can be exploited therapeutically.

SIGNIFICANCE

Currently, processes that mediate progression of otherwise indolent tumors are not well understood, making it difficult to accurately predict which cancer patients are likely to relapse. Our findings highlight the macroenvironment as an important component of disease progression that can be exploited to more accurately identify patients who would benefit from adjuvant therapy.

Circulating biomarkers in advanced renal cell carcinoma: clinical applications

Advances in understanding the biology of renal cell carcinoma (RCC) have resulted in treatment strategies based on molecularly targeted agents that have substantially improved the outcomes of patients with metastatic RCC. Agents targeting the vascular endothelial growth factor pathway and the mammalian target of rapamycin have shown efficacy in randomized clinical trials and received international approval for treating RCC. Multiple candidate biomarkers of the biologic activity of such targeted therapies as well as markers of treatment response and patients' prognosis are being evaluated to improve drug development and to identify patients who may obtain the greatest benefit from the various treatment options. This review summarizes recent developments in identifying circulating biomarkers of targeted therapies for metastatic RCC, including soluble proteins and circulating cells.

Systemic VHL gene functions and the VHL disease

The von Hippel-Lindau tumor suppressor gene (VHL) is best known as an E3 ubiquitin ligase that negatively regulates the hypoxia inducible factor (HIF). VHL mutations are the genetic defects underlying several human diseases including polycythemia, familial VHL tumor syndrome and sporadic renal cell carcinoma. VHL mutations can lead to cell-autonomous phenotypes in the tumor cells. However, non-tumor cell-autonomous functions of VHL have also been noted. VHL tumor-derived cytokines can promote inflammation and induce mobilization of endothelial progenitor cells. Up-regulation of HIF caused by VHL loss-of-function mutants, including heterozygotes, has been shown to increase the activities of hematopoietic stem cells, endothelial cells and myeloid cells. As such, systemic functions of VHL likely play important roles in the development of VHL disease.

A flow cytometric protocol for enumeration of endothelial progenitor cells and monocyte subsets in human blood

BACKGROUND

Accumulating evidence intensively advises circulating endothelial progenitor cells (EPCs) and monocyte subsets as surrogate cellular biomarkers in cardiovascular and cancer disease. However, a general standard on their quantification is still elusive, thus precluding a routine monitoring and comparative interpretation of clinical studies.

OBJECTIVE

We intend to develop an advanced and express flow cytometric protocol for proper ex vivo quantification of monocyte subsets and EPCs in human blood.

METHODS

We employ now lyse/no-wash procedure and bead-based determination of absolute cell counts. We use three-color antibody panels at appropriate compensation. Analysis of rare events and low antigen expression in the EPC experiment is strengthening by sequential gating with exclusion of dead cells, as well as by matching high-intensity fluorochromes to low-density markers and by implementing the fluorescence-minus-one control.

RESULTS

Analysis of peripheral blood of ten healthy donors revealed median (IQR) value of 1.88 (1.35-2.85) viable CD45(dim)CD34)VEGFR2+ EPCs per microliter. Analysis of monocytes revealed 329.5 (264.5-374.8), 16.0 (8.0-22.2) and 26.5 (19.8-36.3) cells per microliter for classical CD14++(high))CD16⁻, intermediate CD14++CD16+(mid) and non-classical CD14+(low))CD16++ monocytes.

CONCLUSION

Our current protocol provides quantitative information under a simple gating logic while using commonly accepted fluorochromes. This assay is therefore highly adapted for routine use.

Defining an individualized treatment strategy for metastatic renal cancer

Treatment of metastatic renal cell carcinoma (mRCC) has evolved dramatically within the past 10 years with the advent of therapy targeting the angiogenesis and mammalian target of rapamycin (mTOR) pathways. These therapies rapidly supplanted immunotherapy as a first-line systemic treatment option. Response rates, however, continue to vary, largely due to mRCC's clinical and molecular heterogeneity. This article reviews current understanding of mRCC biology and available treatments, discusses novel biomarkers that improve prognostication and may be able to predict response, and integrates available literature on surgical and systemic therapies into an individualized strategy.

Prognostic value of circulating VEGFR2+ bone marrow-derived progenitor cells in patients with advanced cancer

We hypothesised that host-related markers, possibly reflecting tumour aggressiveness, such as circulating endothelial cells (CEC) and circulating VEGFR2(+) bone marrow-derived (BMD) progenitor cells, could have prognostic value in patients with advanced cancer enrolled in early anticancer drug development trials. Baseline CECs (CD45(-)CD31(+)CD146(+)7AAD(-) cells) and circulating VEGFR2(+)-BMD progenitor cells (defined as CD45(dim)CD34(+)VEGFR2(+)7AAD(-) cells) were measured by flow-cytometry in 71 and 58 patients included in phase 1 trials testing novel anti-vascular or anti-angiogenic agents. Correlations between levels of CECs, circulating VEGFR2(+)-BMD progenitor cells, clinical and biological prognostic factors (i.e. the Royal Marsden Hospital (RMH) score), and overall survival (OS) were studied. The median value of CECs was 12 CEC/ml (range 0-154/ml). The median level of VEGFR2(+)-BMD progenitor cells was 1.3% (range 0-32.5%) of circulating BMD-CD34(+) progenitors. While OS was not correlated with CEC levels, it was significantly worse in patients with high VEGFR2(+)-BMD progenitor levels (>1%) (median OS 9.0 versus 17.0 months), and with a RMH prognostic score >0 (median OS 9.0 versus 24.2 months). The prognostic value of VEGFR2(+)-BMD progenitor levels remained significant (hazard ratio (HR) = 2.3, 95% confidence interval (CI), 1.1-4.6, p = 0.02) after multivariate analysis. A composite VEGFR2(+)-BMD progenitor level/RHM score ≥ 2 was significantly associated with an increased risk of death compared to scores of 0 or 1 (median OS 9.0 versus 18.4 months, HR = 2.6 (95%CI, 1.2-5.8, p = 0.02)). High circulating VEGFR2(+)-BMD progenitor levels are associated with poor prognostics and when combined to classical clinical and biological parameters could provide a new tool for patient selection in early anticancer drug trials.

Clinical value of circulating endothelial cell detection in oncology

Given the importance of tumor vasculature in tumor biology and as a target for treatment, there is an increasing need for biomarkers that reflect effects impacting tumor vasculature accurately. Circulating endothelial cells (CECs) increase in number as a result of vascular damage in cancer and several other diseases. CEC count constitutes a promising tool for monitoring disease activity with potential to assess prognosis and response to treatment. Here, we address the current state-of-the-art of CEC enumeration as a biomarker in clinical oncology. We focus on technical issues concerning CEC detection, review results from clinical studies and explore future potential applications.

Tyrosine kinase inhibitors in the treatment of advanced renal cell carcinoma: focus on pazopanib

Advances in our understanding of renal cancer biology have led to a new treatment paradigm in renal cancer. Tyrosine kinase inhibitors (TKI), that target the intracellular kinase domain of the VEGF receptor, have become established as the most successful class of agent in this disease. Three TKIs are currently approved for use in patients with advanced disease. Newer, more potent inhibitors have reached phase III clinical testing, meaning others are likely to follow. In 2009, pazopanib became the most recent TKI to receive FDA approval. This review sets out to discuss the key opportunities and challenges associated with TKI use in RCC, focusing particularly on pazopanib. We also review the current place of pazopanib in the management of patients with advanced disease, in what is a rapidly evolving therapeutic landscape.

Biomarkers in tumor angiogenesis and anti-angiogenic therapy

Tumor angiogenesis has been identified to play a critical role in tumor growth and tumor progression, and is regulated by a balance of angiogenic and anti-angiogenic cytokines. Among them VEGF (vascular endothelial growth factor) and its signaling through its receptors are of crucial relevance. Inhibition of VEGF signaling by monoclonal antibodies or small molecules (kinase inhibitors) has already been successfully established for the treatment of different cancer entities and multiple new drugs are being tested in clinical trials. However not all patients are likely to respond to these therapies, but to date there are no reliable biomarkers available to predict therapy response. Many studies integrated biomarker programs in their study protocols, thus several potential biomarkers have been identified which are currently under clinical investigation in prospective randomized studies. This review intends to give an overview of the described potential biomarkers as well as different imaging techniques such as ultrasound and magnetic resonance imaging that can indicate benefit, resistance and toxicity to anti-angiogenic therapies.

Biomarkers to predict response to sunitinib therapy and prognosis in metastatic renal cell cancer

Sunitinib is an orally-administered, multitargeted tyrosine kinase inhibitor. The main targets are vascular endothelial growth factor receptor (VEGFR)-1, VEGFR-2, VEGFR-3, platelet-derived growth factor receptor (PDGFR)-α, and PDGFR-β. Among therapeutic targeting agents, it is the best available in the USA for patients with metastatic renal cell cancer (RCC). Well-constructed clinical trials have led to the worldwide approval of various agents for RCC. However, in clinical practice, it remains difficult to determine the best treatment strategy with these agents. Therefore, the identification of biomarkers to predict response and side-effects and to select optimal dosages is urgently needed. Potential mechanisms of action and resistance need to be understood in order to make accurate predictions. This article briefly reviews candidate biomarkers of sunitinib therapy in terms of clinical variables, genetic factors, and circulating proteins and endothelial cells. Although further validation and implementation is necessary, if validated, biomarkers will help measure the therapeutic response in individual patients and establish treatment strategies for metastatic RCC.