Prognostic impact of circulating tumor cells assessed with the CellSearch System™ and AdnaTest Breast™ in metastatic breast cancer patients: the DETECT study

Functional Diagnostic and Therapeutic Nanoconstructs for Efficient Probing of Circulating Tumor Cells

The circulation of tumor cells in peripheral blood is mostly recognized as a prerequisite for cancer progression or systemic invasion, and it correlates with the pivotal hallmark of malignancies known as metastasis. Multiple detection schemes for circulating tumor cells (CTCs) have emerged as the most discerning criteria for monitoring the outcome of anticancer therapy. Therefore, there has been a tremendous increase in the use of robust nanostructured platforms for observation of these mobile tumor cells through various simultaneous diagnosis and treatment regimens developed from conventional techniques. This review seeks to give detailed information about the nature of CTCs as well as techniques for exploiting specific biomarkers to help monitor cancer via detection, capturing, and analysis of unstable tumor cells. We will further discuss nanobased diagnostic interventions and novel platforms which have recently been developed from versatile nanomaterials such as polymer nanocomposites, metal organic frameworks, bioderived nanomaterials and other physically responsive particles with desirable intrinsic and external properties. Herein, we will also include in vivo nanotheranostic platforms which have received a lot of attention because of their enormous clinical potential. In all, this review sums up the general potential of key promising nanoinspired systems as well as other advanced strategies under research and those in clinical use.

Circulating tumor cells (CTCs) and cytokeratin 19 (CK19) mRNA as prognostic factors in heavily pretreated patients with metastatic breast cancer

INTRODUCTION

Circulating tumor cell (CTC) count and cytokeratin 19 (CK19) mRNA expression have a prognostic value for patients with metastatic breast cancer (MBC), but their clinical utility remains controversial. We studied CTC count and CK19 mRNA expression in the peripheral blood samples from heavily pretreated patients with MBC and their correlations with prognosis and response to the subsequent line of therapy.

METHODS

This prospective observational study included 67 consecutive patients with MBC who were on progression to systemic therapy, and criteria for a new line of systemic treatment were proposed outside a clinical trial. CTC counts and CK19 mRNA expression were measured by the CellSearch^® and RT-PCR methods, respectively, before and after the first cycle of treatment. Progression-free survival (PFS) was defined as the time elapsed between the initiation of the treatment and either the date of clinical or radiological tumor progression or death from any cause or the last follow-up. Cox proportional hazards regression model was used to assess the univariate prognostic value of CTC and CK19 mRNA expression on PFS and Kaplan-Meier estimates. A multivariate Cox model was also used to additionally account for phenotype and visceral disease.

RESULTS

The mean age was 60 (range 35-86) years, and the average number of previous treatments was 3 (range 1-10); 42 patients (62.6%) were ER+ and 38 patients (56.7%) had visceral disease. The median PFS rate was 8 months (95% CI: 3.7-8.2). Univariate analyses showed a significant effect of the initial value of CK19 mRNA expression (HR = 2.00; 95% CI: 1.05-3.8; p = 0.03) and for the second value of CTC (HR = 2.18; 95% CI: 1.22-3.9; p = 0.009) but did not reach statistical significance for the initial value of CTC and the second value of CK19 mRNA expression. The estimated PFS rates at 6 and 12 months were 75% and 31% for patients with a low initial value of CK19 mRNA expression and 36% and 10% for those with a high initial value of CK19 mRNA expression, respectively (p: 0.022). Further, the estimated PFS rates at 6 and 12 months were 86% and 65% for patients with a low second value of CTC and 76% and 47% for those with a high second value of CTC, respectively (p: 0.004). In the multivariate analysis adjusted for phenotype, visceral disease, and the last treatment performed, only the effect of the second value of CTC remained significant (HR = 2.7, p = 0.004).

CONCLUSIONS

CK19 mRNA expression and CTC count appeared clinically meaningful in pretreated patients with MBC, even when adjusted for phenotype and visceral disease involvement. These results support the use of CK19 and CTC as relevant biomarkers for predicting clinical response in MBC.

Circulating tumor cell isolation, culture, and downstream molecular analysis

Circulating tumor cells (CTCs) are a major contributor of cancer metastases and hold a promising prognostic significance in cancer detection. Performing functional and molecular characterization of CTCs provides an in-depth knowledge about this lethal disease. Researchers are making efforts to design devices and develop assays for enumeration of CTCs with a high capture and detection efficiency from whole blood of cancer patients. The existing and on-going research on CTC isolation methods has revealed cell characteristics which are helpful in cancer monitoring and designing of targeted cancer treatments. In this review paper, a brief summary of existing CTC isolation methods is presented. We also discuss methods of detaching CTC from functionalized surfaces (functional assays/devices) and their further use for ex-vivo culturing that aid in studies regarding molecular properties that encourage metastatic seeding. In the clinical applications section, we discuss a number of cases that CTCs can play a key role for monitoring metastases, drug treatment response, and heterogeneity profiling regarding biomarkers and gene expression studies that bring treatment design further towards personalized medicine.

Filtration based assessment of CTCs and CellSearch® based assessment are both powerful predictors of prognosis for metastatic breast cancer patients

Background

The assessment of circulating tumor cells (CTCs) has been shown to enable monitoring of treatment response and early detection of metastatic breast cancer (MBC) recurrence. The aim of this study was to compare a well-established CTC detection method based on immunomagnetic isolation with a new, filtration-based platform.

Methods

In this prospective study, two 7.5 ml blood draws were obtained from 60 MBC patients and CTC enumeration was assessed using both the CellSearch® and the newly developed filtration-based platform. We analyzed the correlation of CTC-positivity between both methods and their ability to predict prognosis. Overall survival (OS) was calculated and Kaplan-Meier curves were estimated with thresholds of ≥1 and ≥5 detected CTCs.

Results

The CTC positivity rate of the CellSearch® system was 56.7% and of the filtration-based platform 66.7%. There was a high correlation of CTC enumeration obtained with both methods. The OS for patients without detected CTCs, regardless of the method used, was significantly higher compared to patients with one or more CTCs (p < 0.001). The median OS of patients with no CTCs vs. ≥ 1 CTC assessed by CellSearch® was 1.83 years (95% CI: 1.63–2.02) vs. 0.74 years (95% CI: 0.51–1.52). If CTCs were detected by the filtration-based method the median OS times were 1.88 years (95% CI: 1.74–2.03) vs. 0.59 years (95% CI: 0.38–0.80).

Conclusions

The newly established EpCAM independently filtration-based system is a suitable method to determine CTC counts for MBC patients. Our study confirms CTCs as being strong predictors of prognosis in our population of MBC patients.

Circulating and disseminated tumor cells: diagnostic tools and therapeutic targets in motion

Enumeration of circulating tumor cells (CTCs) in peripheral blood with the gold standard CellSearchTM has proven prognostic value for tumor recurrence and progression of metastatic disease. Therefore, the further molecular characterization of isolated CTCs might have clinical relevance as liquid biopsy for therapeutic decision-making and to monitor disease progression. The direct analysis of systemic cancer appears particularly important in view of the known disparity in expression of therapeutic targets as well as epithelial-to-mesenchymal transition (EMT)-based heterogeneity between primary and systemic tumor cells, which all substantially complicate monitoring and therapeutic targeting at present. Since CTCs are the potential precursor cells of metastasis, their in-depth molecular profiling should also provide a useful resource for target discovery. The present review will discuss the use of systemically spread cancer cells as liquid biopsy and focus on potential target antigens.

The Predictive Value of Circulating Tumor Cells in Ovarian Cancer: A Meta Analysis

OBJECTIVE

Studies have confirmed that patients with circulating tumor cells (CTCs) in their peripheral blood (PB) or disseminated tumor cells (DTCs) in bone marrow (BM) might have bad prognosis. In this paper, we discuss whether CTCs/DTCs would be an appropriate biomarker to predict the prognosis of ovarian cancer.

METHODS

We systematically searched PubMed, EMBASE, Cochrane library, and Chinese National Knowledge Infrastructure to collect relevant studies published from the time the database were created to February 2014. Studies quality was assessed by Newcastle-Ottawa Scale. The effect size was estimated by hazard ratio (HR) and corresponding 95% confidence interval (95% CI). Meta-analysis was conducted with STATA Version 12.0.

RESULTS

Eight studies of 1184 patients were included in the final analysis. In the PB group, it showed that patients with positive CTCs had significantly shorter overall survival and disease-free survival than patients with negative CTCs (HR, 2.09; CI, 1.13-3.88 and HR, 1.72; CI, 1.32-2.25, respectively). The same result was shown with DTCs in the BM group (HR, 1.61; CI, 1.27-2.04 and HR, 1.44; CI, 1.15-1.80, respectively). We also discussed the influence of CTCs/DTCs on International Federation of Gynecology and Obstetrics stage, pathological grade with odds ratio and 95% CI. However, it did not show any statistical significance.

CONCLUSIONS

The CTCs/DTCs might be a new biomarker to predict the prognosis of ovarian cancer. Future studies are needed to confirm this consequence.

Clinical utility of non-EpCAM based circulating tumor cell assays

Methods enabling the isolation, detection, and characterization of circulating tumor cells (CTCs) in blood have clear potential to facilitate precision medicine approaches in patients with cancer, not only for prognostic purposes but also for prediction of the benefits of specific therapies in oncology. However, current CTC assays, which capture CTCs based on expression of epithelial cell adhesion molecule (EpCAM), fail to capture cells from de-differentiated tumors and carcinomas undergoing loss of the epithelial phenotype during the invasion/metastatic process. To address this limitation, many groups are developing non-EpCAM based CTC assays that incorporate nanotechnology to improve test sensitivity for rare but important cells that may otherwise go undetected, and therefore may improve upon clinical utility. In this review, we outline emerging non-EpCAM based CTC assays utilizing nanotechnology approaches for CTC capture or characterization, including dendrimers, magnetic nanoparticles, gold nanoparticles, negative selection chip or software-based on-slide methods, and nano-scale substrates. In addition, we address challenges that remain for the clinical translation of these platforms.

Concordance of anaplastic lymphoma kinase (ALK) gene rearrangements between circulating tumor cells and tumor in non-small cell lung cancer

Anaplastic lymphoma kinase (ALK) gene rearrangement in non-small cell lung cancer (NSCLC) is routinely evaluated by fluorescent in-situ hybridization (FISH) testing on biopsy tissues. Testing can be challenging however, when suitable tissue samples are unavailable. We examined the relevance of circulating tumor cells (CTC) as a surrogate for biopsy-based FISH testing. We assessed paired tumor and CTC samples from patients with ALK rearranged lung cancer (n = 14), ALK-negative lung cancer (n = 12), and healthy controls (n = 5) to derive discriminant CTC counts, and to compare ALK rearrangement patterns. Blood samples were enriched for CTCs to be used for ALK FISH testing. ALK-positive CTCs counts were higher in ALK-positive NSCLC patients (3–15 cells/1.88 mL of blood) compared with ALK-negative NSCLC patients and healthy donors (0–2 cells/1.88 mL of blood). The latter range was validated as the ‘false positive’ cutoff for ALK FISH testing of CTCs. ALK FISH signal patterns observed on tumor biopsies were recapitulated in CTCs in all cases. Sequential CTC counts in an index case of lung cancer with no evaluable tumor tissue treated with crizotinib showed six, three and eleven ALK-positive CTCs per 1.88 mL blood at baseline, partial response and post-progression time points, respectively. Furthermore, ALK FISH rearrangement suggestive of gene copy number increase was observed in CTCs following progression. Recapitulation of ALK rearrangement patterns in the tumor on CTCs, suggested that CTCs might be used to complement tissue-based ALK testing in NSCLC to guide ALK-targeted therapy when suitable tissue biopsy samples are unavailable for testing.

Liquid Biopsy in Clinical Management of Breast, Lung, and Colorectal Cancer

Examination of tumor molecular characteristics by liquid biopsy is likely to greatly influence personalized cancer patient management. Analysis of circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and tumor-derived exosomes, all collectively referred to as “liquid biopsies,” are not only a modality to monitor treatment efficacy, disease progression, and emerging therapy resistance mechanisms, but they also assess tumor heterogeneity and evolution in real time. We review the literature concerning the examination of ctDNA and CTC in a diagnostic setting, evaluating their prognostic, predictive, and monitoring capabilities. We discuss the advantages and limitations of various leading ctDNA/CTC analysis technologies. Finally, guided by the results of clinical trials, we discuss the readiness of cell-free DNA and CTC as routine biomarkers in the context of various common types of neoplastic disease. At this moment, one cannot conclude whether or not liquid biopsy will become a mainstay in oncology practice.

The significant prognostic value of circulating tumor cells in triple-negative breast cancer: a meta-analysis

Background

The clinical validity of circulating tumor cells (CTCs) is still controversial in patients with triple-negative breast cancer (TNBC).

Methods

A comprehensive literature search was performed to identify relevant articles in the PubMed, Web of Science, MEDLINE, and Embase databases through September 2015. The outcomes of interest were disease progression and overall survival. The hazard ratio (HR) and 95% confidence interval (95% CI) were considered the effect indicators and were pooled in meta-analyses under a fixed- or random-effect model according to heterogeneity.

Results

Ten of the eligible studies were included for a total of 642 enrolled TNBC patients. Overall analyses revealed that the presence of CTCs predicted aggressive disease progression (HR = 2.18, 95% CI = 1.59-2.99, P_{heterogeneity} = 0.010, I² = 52.2%) and reduced overall survival (HR = 2.02, 95% CI = 1.59-2.57, P_{heterogeneity} = 0.169, I² = 26.6%). Further subgroup analyses demonstrated that CTC-positive patients also had poor disease progression and overall survival in different subsets, including cancer stage.

Conclusion

Our meta-analysis provides strong evidence that detection of CTC in the peripheral blood is an independent prognosticator of poor survival outcomes for TNBC patients.

Circulating Tumor Cells and Implications of the Epithelial-to-Mesenchymal Transition

The majority of cancer-related deaths result from metastasis, the process by which cancer cells escape the primary tumor site and enter into the blood circulation in order to disseminate to secondary locations throughout the body. Tumor cells found within the circulation are referred to as circulating tumor cells (CTCs), and their detection and enumeration correlate with poor prognosis. The epithelial-to-mesenchymal transition (EMT) is a dynamic process that imparts epithelial cells with mesenchymal-like properties, thus facilitating tumor cell dissemination and contributing to metastasis. However, EMT also results in the downregulation of various epithelial proteins typically utilized by CTC technologies for enrichment and detection of these rare cells, resulting in reduced detection of some CTCs, potentially those with a more metastatic phenotype. In addition to the current clinical role of CTCs as a prognostic biomarker, they also have potential as a predictive biomarker via CTC characterization. However, CTC characterization is complicated by the unknown biological significance of CTCs possessing an EMT-like phenotype, and the ability to capture and understand this CTC subpopulation is an essential step in the utilization of CTCs for patient management. This chapter will review the process of EMT and its contribution to metastasis; discusses current and future clinical applications of CTCs; and describes both traditional and novel methods for CTC enrichment, detection, and characterization with a specific focus on CTCs with an EMT phenotype.

Enhancing size based size separation through vertical focus microfluidics using secondary flow in a ridged microchannel

High throughput size based separation and sorting of bioparticles and cells is critical to a variety of biomedical processing steps for medical diagnostics and pharmaceutical purification. Improving microfluidic size-based particle/cell sorting is a challenge to better address the need for generating more homogeneous subpopulations for study and use. We propose a novel advance to microfluidic sorting devices that uses three-dimensional focusing of the sample to optimally position particles to amplify the size-dependent differences in trajectories caused by differential secondary flows. The result is an increase in the purity of small particles by 35- fold and large particles by 8-fold in comparison to unfocused flow. Our simulated and experimental data reveal for the first time that positioning particles in three-dimensional space can be used to better leverage the differential lateral movement of particles with different sizes as they flow in microchannel with transverse secondary flows. The focusing approach may also be useful to improve positioning of particles with inertial channels with multiple equilibrium positions. This technique performs continuous-flow, high throughput size based sorting of millions of particles and cells in a minute without any pre and post-processing. We have also demonstrated improved enrichment and recovery of white blood cells from human blood.

Circulating Tumour Cells, Circulating Tumour DNA and Circulating MicroRNA in Metastatic Breast Carcinoma - What is the Role of Liquid Biopsy in Breast Cancer?

Dissemination of tumour cells and the development of solid metastases occurs via blood vessels and lymphatics. Circulating tumour cells (CTCs) and circulating tumour DNA (ctDNA) can be detected in venous blood in patients with early and metastatic breast cancer, and their prognostic relevance has been demonstrated on numerous occasions. Repeated testing for CTCs and ctDNA, or regular so-called "liquid biopsy", can be performed easily at any stage during the course of disease. Additional molecular analysis allows definition of tumour characteristics and heterogeneity that may be associated with treatment resistance. This in turn makes personalised, targeted treatments possible that may achieve both improved overall survival and quality of life.

Clinical Validity of Detecting Circulating Tumor Cells by AdnaTest Assay Compared With Direct Detection of Tumor mRNA in Stabilized Whole Blood, as a Biomarker Predicting Overall Survival for Metastatic Castration-Resistant Prostate Cancer Patients

Circulating tumor cell (CTC) number measured with the CellSearch assay is prognostic for survival in metastatic castration-resistant prostate cancer before and after therapy. Using a standard operating protocol for sample collection, processing, and analysis, we compared detection rates of CellSearch performed using US Food and Drug Administration-cleared methodology with a second positive selection assay, AdnaTest, and a nonselection polymerase chain reaction (PCR)-based (direct detection PCR [DDPCR]) assay in 55 blood samples from 47 men with progressive metastatic castration-resistant prostate cancer. AdnaTest requires processing within 4 hours of the draw and detects KLK3, PSMA, and EGFR transcripts in cells captured on magnetic beads. The DDPCR assay can be processed up to 7 days after a draw and detects KLK2, KLK3, HOXB13, GRHL2, and FOXA1 genes. AdnaTest and DDPCR were considered positive if at least 1 transcript was detected. AdnaTest detected CTCs in 34 samples (62%; 95% confidence interval [CI], 48%-75%), of which 23 (68%) had unfavorable CTC counts by CellSearch. A positive DDPCR result was seen in 38 cases (69%; 95% CI, 55%-81%), including 24 (63%) with unfavorable CellSearch CTC counts. CellSearch found unfavorable CTC counts in 25 samples (45%; 95% CI, 33%-58%). Sensitivities were similar between the AdnaTest and DDPCR assays, and both were more sensitive than CellSearch. Concordance probability estimates (possible values, 0.5-1.0) associating the biomarker result with survival were similar: 0.77 (SE, 0.07) for AdnaTest, 0.72 (SE, 0.08) for DDPCR, and 0.76 (SE, 0.06) for CellSearch. Overall detection rates between the AdnaTest and DDPCR assays were similar, and both were superior to CellSearch. The DDPCR assay required the lowest blood volume, least on-site processing, and longest stability for batch processing.

Biological and Molecular Characterization of Circulating Tumor Cells: A Creative Strategy for Precision Medicine?

Circulating tumor cells (CTCs) are a group of rare cells disseminated from either primary or metastatic tumors into the blood stream. CTCs are considered to be the precursor of cancer metastasis. As a critical component of liquid biopsies, CTCs are a unique tool to understand the formation of metastasis and a valuable source of information on intratumor heterogeneity. Much effort has been invested in technologies for the detection of CTCs because they are rare cells among the vast number of blood cells. Studies in various cancers have repeatedly demonstrated that increased CTC counts prior to or during treatment are significantly associated with poor outcomes. In the new era of precision medicine, the study of CTCs reaches far beyond detection and counting. The rapidly growing field of analytical platforms for rare-cell analysis allows in-depth characterization of CTCs at the bulk cell and single-cell level. Genetic profiling of CTCs may provide an insight into the real-time tumor status, may allow the monitoring and evaluation of treatment response in clinical routine, and may lead to the development of novel therapeutic targets as well.

An integrated microfluidic system for the isolation and detection of ovarian circulating tumor cells using cell selection and enrichment methods

Gynecological cancer is difficult to be diagnosed at early stages. The relatively high mortality rate has been a serious issue accordingly. We herein reported a diagnosis method by using circulating tumor cells (CTCs) which have been extensively explored as a potential tool for diagnostics and prognostics of ovarian cancers. Nonetheless, the detection of CTCs still remains a challenge because of the difficulty in isolating them from whole blood samples since they are shed into the vasculature from primary tumors and circulate irregularly in the bloodstream in extremely low concentrations. In this work, we reported a new, integrated microfluidic system capable of (1) red blood cells lysis, (2) white blood cell (WBC) depletion via a negative selection process, and (3) capture of target cancer cells from whole blood samples using aptamer-binding technology. Furthermore, this is the first time that an aptamer was used to capture ovarian cancer cells owing to its high affinity. The new microfluidic chip could efficiently perform the entire process in one hour without human intervention at a high recovery rate and a low false positive detection rate when compared with antibody-based systems. A high recovery rate for the isolation of CTCs within a short period of time has been reported when compared to the traditional negative or positive selection approach by using traditional antibody biomarkers. More importantly, "false positive" results from WBCs could be significantly alleviated due to the high specificity of the cancer cell-specific aptamers. The developed integrated microfluidic system could be promising for the isolation and detection of CTCs, which could be used for early diagnosis and prognosis of cancers.

Circulating tumor markers: harmonizing the yin and yang of CTCs and ctDNA for precision medicine

Current trajectory of clinical care is heading in the direction of personalized medicine. In an ideal scenario, clinicians can obtain extensive diagnostic and prognostic information via minimally-invasive assays. Information available in the peripheral blood has the potential to bring us closer to this goal. In this review we highlight the contributions of circulating tumor cells and circulating tumor DNA and RNA (ctDNA/ctRNA) towards cancer therapeutic field. We discuss clinical relevance, summarize available and upcoming technologies, and hypothesize how future care could be impacted by a combined study.

Detection of Circulating Tumour Cells in Urothelial Cancers and Clinical Correlations: Comparison of Two Methods

Circulating tumour cells (CTC) are identified exploiting their protein/gene expression patterns or distinct size compared to blood cells. Data on CTC in bladder cancer (BC) are still scarce. We comparatively analyzed CTC enrichment by AdnaTest ProstateCancerSelect (AT) and ScreenCell®Cyto (SC) kits, combined with identification by EPCAM, MUC1, and ERBB2 expression and by cytological criteria, respectively, in 19 nonmetastatic (M₀) and 47 metastatic (M₊) BC patients, at baseline (T₀) and during treatment (T₁). At T₀, CTC positivity rates by AT were higher in M₊ compared to M₀ cases (57.4% versus 25%, p = 0.041). EPCAM was detected in 75% of CTC-positive samples by AT, showing increasing expression levels from T₀ to T₁ (median (interquartile range, IQR): 0.18 (0.07-0.42) versus 0.84 (0.33-1.84), p = 0.005) in M₊ cases. Overall, CTC positivity by SC was around 80% regardless of clinical setting and time point of analysis, except for a lower occurrence at T₁ in M₀ cases. At T₀, circulating tumour microemboli were more frequently (25% versus 8%) detected and more numerous in M₊ compared to M₀ patients. The approach used for CTC detection impacts the outcome of CTC studies. Further investigations are required to clarify the clinical validity of AT and SC in specific BC clinical contexts.

Circulating Tumor Cells: Markers and Methodologies for Enrichment and Detection

Cancer is a leading cause of disease worldwide; however, nowadays many points of its initiation processes are unknown. In this chapter, we are focusing on the role of liquid biopsies in cancer detection and progression. CTCs are one of the main components of liquid biopsies, they represent a subset of tumor cells that have acquired the ability to disseminate from the primary tumor and intravasate to the circulatory system. The greatest challenge in the detection of CTCs is their rarity in the blood. Human blood consists of white blood cells (5-10 × 10⁶/mL), red blood cells (5-9 × 10⁹/mL), and platelets (2.5-4 × 10⁸/mL); very few CTCs will be present even in patients with known metastatic disease, with often less than one CTC per mL of blood. CTCs are found in frequencies on the order of 1-10 CTCs per mL of whole blood in patients with metastatic disease, and it is reduced in half for non-metastatic stages. Therefore, accurate methodologies for their capture and analysis are really important. The main aim of the present chapter is to describe different methodologies for CTCs capturing and analysis.

Potential Role of Circulating Tumor Cell Detection and Monitoring in Breast Cancer: A Review of Current Evidence

The phenomenon of hematogenous tumor cell dissemination in patients with solid tumors has been extensively explored over the last decades. Breast cancer research investigated at first disseminated tumor cells in the bone marrow; however, the focus soon moved to circulating tumor cells (CTCs) in the peripheral blood as blood is easily accessible without an invasive procedure. The prognostic significance of CTC presence has been shown in large studies both in adjuvant and metastatic setting and commercially available detection assays have been evaluated for monitoring in clinical trials. Beyond detection and enumeration of CTCs, the characterization of single tumor cells may enhance our knowledge on disease progression and thus optimize treatment choices.

Detection of circulating tumor cells using manually performed immunocytochemistry (MICC) does not correlate with outcome in patients with early breast cancer - Results of the German SUCCESS-A- trial

Background

Recently, the prognostic significance of circulating tumor cells (CTCs) in primary breast cancer as assessed using the Food-and-Drug-Administration-approved CellSearch® system has been demonstrated. Here, we evaluated the prognostic relevance of CTCs, as determined using manually performed immunocytochemistry (MICC) in peripheral blood at primary diagnosis, in patients from the prospectively randomized multicenter SUCCESS-A trial (EudraCT2005000490-21).

Methods

We analyzed 23 ml of blood from 1221 patients with node-positive or high risk node-negative breast cancer before adjuvant taxane-based chemotherapy. Cells were separated using a density gradient followed by epithelial cell labeling with the anti-cytokeratin-antibody A45-B/B3, immunohistochemical staining with new fuchsin, and cytospin preparation. All cytospins were screened for CTCs, and the cutoff for positivity was at least one CTC. The prognostic value of CTCs with regard to disease-free survival (DFS), distant disease-free survival (DDFS), breast-cancer-specific survival (BCSS), and overall survival (OS) was assessed using both univariate analyses applying the Kaplan–Meier method and log-rank tests, and using multivariate Cox regressions adjusted for other predictive factors.

Results

In 20.6 % of all patients (n = 251) a median of 1 (range, 1–256) CTC was detected, while 79.4 % of the patients (n = 970) were negative for CTCs before adjuvant chemotherapy. A pT1 tumor was present in 40.0 % of patients, 4.8 % had G1 grading and 34.6 % were node-negative. There was no association between CTC positivity and tumor stage, nodal status, grading, histological type, hormone receptor status, Her2 status, menopausal status or treatment. Univariate survival analyses based on a median follow-up of 64 months revealed no significant differences between CTC-positive and CTC-negative patients with regard to DFS, DDFS, BCSS, or OS. This was confirmed by fully adjusted multivariate Cox regressions, showing that the presence of CTCs (yes/no) as assessed by MICC did not predict DFS, DDFS, BCSS or OS.

Conclusions

We could not demonstrate prognostic relevance regarding CTCs that were quantified using the MICC method at the time of primary diagnosis in our cohort of early breast cancer patients. Further studies are necessary to evaluate if the presence of CTCs assessed using MICC has prognostic relevance, or can be used for risk stratification and treatment monitoring in adjuvant breast cancer.

Trial registration

The ClinicalTrial.gov registration ID of this prospectively randomized trial is NCT02181101; the (retrospective) registration date was June 2014 (study start date September 2005).

The potential for liquid biopsies in the precision medical treatment of breast cancer

Currently the clinical management of breast cancer relies on relatively few prognostic/predictive clinical markers (estrogen receptor, progesterone receptor, HER2), based on primary tumor biology. Circulating biomarkers, such as circulating tumor DNA (ctDNA) or circulating tumor cells (CTCs) may enhance our treatment options by focusing on the very cells that are the direct precursors of distant metastatic disease, and probably inherently different than the primary tumor's biology. To shift the current clinical paradigm, assessing tumor biology in real time by molecularly profiling CTCs or ctDNA may serve to discover therapeutic targets, detect minimal residual disease and predict response to treatment. This review serves to elucidate the detection, characterization, and clinical application of CTCs and ctDNA with the goal of precision treatment of breast cancer.

Plasma S100P level as a novel prognostic marker of metastatic breast cancer

Metastasis is the main cause of death in breast cancer patients. The development of reliable and cost-effective biomarker to evaluate the prognosis of metastatic breast cancer (MBC) patients is of great importance. S100P is a member of S100 family and has been proved to be associated with metastasis establishment.

METHODS

We investigated the plasma S100P levels in 60 healthy controls, 48 primary and 273 metastatic breast cancer patients. The MBC patients were followed-up for disease progression and death up to 3.5 years after recruitment. Radiographic response of MBC patients were also analyzed for investigation on treatment monitoring value of plasma S100P level. We found a robust association between high plasma S100P level (>7 ng/mL) and poor prognosis of metastatic breast cancer (MBC) patients (median progression-free survival time: 5.0 vs. 8.7 months, log-rank test p < 0.001; median overall survival time: 22.5 vs. 31.6 months, log-rank test p < 0.001). The plasma S100P level added additional prognostic relevance to the conventional prognostication model with clinicopathological factors and CTC enumeration. The plasma S100P level decreased significantly after treatment, while the reduction correlated with the radiographic response of the MBC patients. This finding indicates the value of plasma S100P in dynamic evaluation of treatment outcome. We hereby suggest plasma S100P level as a simple and cost-effective marker for the prognosis of metastatic breast cancer.

Nanotechnology for enrichment and detection of circulating tumor cells

Circulating tumor cells (CTCs) are a hallmark of invasive behavior of cancer, responsible for the development of metastasis. Their detection and analysis have significant impacts in cancer biology and clinical practice. However, CTCs are rare events and contain heterogeneous subpopulations, requiring highly sensitive and specific techniques to identify and capture CTCs with high efficiency. Nanotechnology shows strong promises for CTC enrichment and detection owning to the unique structural and functional properties of nanoscale materials. In this review, we discuss the CTC enrichment and detection technologies based on a variety of functional nanosystems and nanostructured substrates, with the goal to highlight the role of nanotechnology in the advancement of basic and clinical CTC research.

The Role of CTCs as Tumor Biomarkers

Detection of Circulating Tumor Cells (CTCs) in peripheral blood can serve as a "liquid biopsy" approach and as a source of valuable tumor markers. CTCs are rare, and thus their detection, enumeration and molecular characterization are very challenging. CTCs have the unique characteristic to be non-invasively isolated from blood and used to follow patients over time, since these cells can provide significant information for better understanding tumour biology and tumour cell dissemination. CTCs molecular characterization offers the unique potential to understand better the biology of metastasis and resistance to established therapies and their analysis presents nowadays a promising field for both advanced and early stage patients. In this chapter we focus on the latest findings concerning the clinical relevance of CTC detection and enumeration, and discuss their potential as tumor biomarkers in various types of solid cancers. We also highlight the importance of performing comparison studies between these different methodologies and external quality control systems for establishing CTCs as tumor biomarkers in the routine clinical setting.

Prognostic value of circulating tumor cells in metastatic breast cancer: a systemic review and meta-analysis

OBJECTIVE

Metastatic breast cancer (MBC) remains the main cause of cancer-related death, and the clinical significance and prognostic role of circulating tumor cells (CTCs) in metastatic breast cancer are still controversial. Here, we conducted a meta-analysis to clarify the correlation between CTCs and the clinicopathological features and prognosis of MBC.

METHODS

We performed a comprehensive search of Pubmed and the ISI Web of Science through December 2014. Only articles that focused on MBC patients and detected CTCs using the CellSearch system were included. The associations between CTCs and survival rate and clinicopathological parameters, including molecular pattern, metastatic region and treatment response, were evaluated.

RESULTS

This meta-analysis included 24 studies (3701 MBC patients), 13 prospective studies and 11 retrospective studies. We found that CTCs were more frequently detected with HER2 + primary tumors (pooled RR = 0.73, 95 % CI = 0.63-0.84). Additionally, higher CTC numbers indicated a worse treatment response (RR = 0.56, 95 % CI = 0.40-0.79), poorer PFS (RR = 0.64, 95 % CI = 0.56-0.73) and poorer OS (RR = 0.69, 95 % CI = 0.64-0.75) in MBC patients.

CONCLUSION

Based on these results, we propose that HER2 positivity could be a significant risk factor for the presence of CTCs. Additionally, CTCs have a significant prognostic value for MBC patients. Therefore, CTCs should be continually monitored to guide the treatment of MBC patients, especially those with HER2 + primary tumors.

Circulating tumor cell technologies†

Circulating tumor cells, a component of the “liquid biopsy”, hold great potential to transform the current landscape of cancer therapy. A key challenge to unlocking the clinical utility of CTCs lies in the ability to detect and isolate these rare cells using methods amenable to downstream characterization and other applications. In this review, we will provide an overview of current technologies used to detect and capture CTCs with brief insights into the workings of individual technologies. We focus on the strategies employed by different platforms and discuss the advantages of each. As our understanding of CTC biology matures, CTC technologies will need to evolve, and we discuss some of the present challenges facing the field in light of recent data encompassing epithelial‐to‐mesenchymal transition, tumor‐initiating cells, and CTC clusters.

We present a comprehensive overview of CTC detection and capture technologies.

We provide a conceptual description of strategies used in different technologies.

We highlight the key features of individual technologies.

We discuss CTC technology performance in the context of clinical studies.

Does primary neoadjuvant systemic therapy eradicate minimal residual disease? Analysis of disseminated and circulating tumor cells before and after therapy

BACKGROUND

Patients with breast cancer (BC) undergoing neoadjuvant chemotherapy (NACT) may experience metastatic relapse despite achieving a pathologic complete response. We analyzed patients with BC before and after NACT for disseminated tumor cells (DTCs) in the bone marrow(BM); comprehensively characterized circulating tumor cells (CTCs), including stem cell-like CTCs (slCTCs), in blood to prove the effectiveness of treatment on these cells; and correlated these findings with response to therapy, progression-free survival (PFS), and overall survival (OS).

METHODS

CTCs (n = 135) and slCTCs (n = 91) before and after NACT were analyzed using the AdnaTest BreastCancer, AdnaTest TumorStemCell, and epithelial-mesenchymal transition (QIAGEN Hannover GmbH Germany). The expression of estrogen receptor, progesterone receptor, and the resistance marker excision repair cross-complementing rodent repair deficiency, complementation group 1 (ERCC1), nuclease were studied in separate single-plex reverse transcription polymerase chain reaction experiments. DTCs were evaluated in 142 patients before and 165 patients after NACT using the pan-cytokeratin antibody A45-B/B3 for immunocytochemistry.

RESULTS

The positivity rates for DTCs, CTCs, and slCTCs were 27 %, 24 %, and 51 % before and 20 %, 8 %, and 20 % after NACT, respectively. Interestingly, 72 % of CTCs present after therapy were positive for ERCC1, and CTCs before (p = 0.005) and after NACT (p = 0.05) were significantly associated with the presence of slCTCs. Whereas no significant associations with clinical parameters were found for CTCs and slCTCs, DTCs were significantly associated with nodal status (p = 0.03) and histology (0.046) before NACT and with the immunohistochemical subtype (p = 0.02) after NACT. Univariable Cox regression analysis revealed that age (p = 0.0065), tumor size before NACT (p = 0.0473), nodal status after NACT (p = 0.0137), and response to NACT (p = 0.0136) were significantly correlated with PFS, whereas age (p = 0.0162) and nodal status after NACT (p = 0.0243) were significantly associated with OS. No significant correlations were found for DTCs or any CTCs before and after therapy with regard to PFS and OS.

CONCLUSIONS

Although CTCs were eradicated more effectively than DTCs, CTCs detected after treatment seemed to be associated with tumor cells showing tumor stem cell characteristics as well as with resistant tumor cell populations that might indicate a worse outcome in the future. Thus, these patients might benefit from additional second-line treatment protocols including bisphosphonates for the eradication of DTCs.

Circulating tumor cells in breast cancer

Over the past decade, technically reliable circulating tumor cell (CTC) detection methods allowed the collection of large datasets of CTC counts in cancer patients. These data can be used either as a dynamic prognostic biomarker or as tumor material for “liquid biopsy”. Breast cancer appears to be the cancer type in which CTC have been the most extensively studied so far, with level‐of‐evidence‐1 studies supporting the clinical validity of CTC count in both early and metastatic stage. This review summarizes and discusses the clinical results obtained in breast cancer patients, the issues faced by the molecular characterization of CTC and the biological findings about cancer biology and metastasis that were obtained from CTC.

In metastatic breast cancer, CTC count is a level‐of‐evidence 1 prognostic dynamic biomarker.

Several interventional trials are ongoing to demonstrate the clinical utility of CTC detection in metastatic breast cancer.

In early breast cancer, CTC count is also a prognostic biomarker, not correlated with the other usual prognostic factors.

Molecular characterization of CTC is promising, trials with anti‐HER2 therapy are ongoing.

Circulating tumor cells isolation: the "post-EpCAM era"

Circulating tumor cells (CTCs) represent a submicroscopic fraction detached from a primary tumor and in transit to a secondary site. The prognostic significance of CTCs in metastatic cancer patients was demonstrated for the first time more than ten years ago. To date, it seems clear enough that CTCs are highly heterogeneous and dynamically change their shape. Thus, the inadequacy of epithelial cell adhesion molecule (EpCAM) as universal marker for CTCs detection seems unquestionable and alternative methods able to recognize a broader spectrum of phenotypes are definitely needed. In this review the pleiotropic functions of EpCAM are discussed in detail and the role of the molecule in the biology of CTCs is critically dissected.

Circulating tumor cells in breast cancer--current status and perspectives

The phenomenon of tumor cell dissemination through the blood stream has been known since the 19th century. Circulating tumor cells (CTCs) may be detected in peripheral blood of patients with breast cancer and may serve as a surrogate marker for minimal residual disease. Prognostic relevance of CTCs has already been demonstrated in early and metastatic breast cancer and commercially available detection systems are currently employed in various clinical trials. Since peripheral blood is an easily accessible compartment, serial reevaluation of CTCs is possible and may contribute to better therapy monitoring. Another potential of CTCs lies in the characterization of tumor cells. Expression profiles may differ between CTCs and primary tumor, which may result in different responses to treatment. Assessment of molecular features of CTCs may be an important step for the optimization of adjuvant and metastatic systemic therapy.

Circulating tumor cells in breast cancer beyond the genotype of primary tumor for tailored therapy

Although TNM staging based on tumor, node lymph status and metastasis status-is the most widely used method in the clinic to classify breast cancer (BC) and assess prognosis, it offers limited information for different BC subgroups. Circulating tumor cells (CTCs) are regarded as minimal residual disease and are proven to have a strong relationship with BC. Detection of ≥5 CTCs per 7.5 mL in peripheral blood predicts poor prognosis in metastatic BC irrespective of other clinical parameters, whereas, in early-stage BC, detection of CK19(+) CTCs are also associated with poor prognosis. Increasing data and clinical trials show that CTCs can improve prognostic accuracy and help tailor treatment for patients with BC. However, heterogeneous CTCs in the process of an epithelial-mesenchymal transition (EMT) in BC makes it a challenge to detect these rare cells. Moreover, the genotypic and phenotypic features of CTCs are different from primary BC tumors. Molecular analysis of CTCs in BC may benefit patients by identifying those amenable to tailored therapy. We propose that CTCs should be used alongside the TNM staging system and the genotype of primary tumor to guide tailored BC diagnosis and treatment.

Using circulating tumor cells to inform on prostate cancer biology and clinical utility

Substantial advances in the molecular biology of prostate cancer have led to the approval of multiple new systemic agents to treat men with metastatic castration-resistant prostate cancer (mCRPC). These treatments encompass androgen receptor directed therapies, immunotherapies, bone targeting radiopharmaceuticals and cytotoxic chemotherapies. There is, however, great heterogeneity in the degree of patient benefit with these agents, thus fueling the need to develop predictive biomarkers that are able to rationally guide therapy. Circulating tumor cells (CTCs) have the potential to provide an assessment of tumor-specific biomarkers through a non-invasive, repeatable "liquid biopsy" of a patient's cancer at a given point in time. CTCs have been extensively studied in men with mCRPC, where CTC enumeration using the Cellsearch® method has been validated and FDA approved to be used in conjunction with other clinical parameters as a prognostic biomarker in metastatic prostate cancer. In addition to enumeration, more sophisticated molecular profiling of CTCs is now feasible and may provide more clinical utility as it may reflect tumor evolution within an individual particularly under the pressure of systemic therapies. Here, we review technologies used to detect and characterize CTCs, and the potential biological and clinical utility of CTC molecular profiling in men with metastatic prostate cancer.

Circulating Epithelial Cells in Patients with Pancreatic Lesions: Clinical and Pathologic Findings

BACKGROUND

Circulating epithelial cell (CEC) isolation has provided diagnostic and prognostic information for a variety of cancers, previously supporting their identity as circulating tumor cells in the literature. However, we report CEC findings in patients with benign, premalignant, and malignant pancreatic lesions using a size-selective filtration device.

STUDY DESIGN

Peripheral blood samples were drawn from patients found to have pancreatic lesions on preoperative imaging at a surgical clinic. Blood was filtered using ScreenCell devices, which were evaluated microscopically by a pancreatic cytopathologist. Pathologic data and clinical outcomes of these patients were obtained from medical records during a 1-year follow-up period.

RESULTS

Nine healthy volunteers formed the control group and were found to be negative for CECs. There were 179 patients with pancreatic lesions that formed the study cohort. Circulating epithelial cells were morphologically similar in patients with a variety of pancreatic lesions. Specifically, CECs were identified in 51 of 105 pancreatic ductal adenocarcinomas (49%), 7 of 11 neuroendocrine tumors (64%), 13 of 21 intraductal papillary mucinous neoplasms (62%), and 6 of 13 patients with chronic pancreatitis. Rates of CEC identification were similar in patients with benign, premalignant, and malignant lesions (p = 0.41). In addition, CEC findings in pancreatic ductal adenocarcinoma patients were not associated with poor prognosis.

CONCLUSIONS

Although CECs were not identified in healthy volunteers, they were identified in patients with benign, premalignant, and malignant pancreatic lesions. The presence of CECs in patients presenting with pancreatic lesions is neither diagnostic of malignancy nor prognostic for patients with pancreatic ductal adenocarcinoma.

Detection of circulating tumor cell-specific markers in breast cancer patients using the quantitative RT-PCR assay

BACKGROUND

Breast cancer is a highly prevalent disease among women worldwide. While the expression of certain proteins within breast cancer tumors is used to determine the prognosis and select therapies, additional markers need to be identified. Circulating tumor cells (CTCs) are constituent cells that have detached from a primary tumor to circulate in the bloodstream. CTCs are considered the main source of breast cancer metastases; therefore, detection of CTCs could be a promising diagnostic method for metastatic breast cancer.

METHODS

In this study, the CircleGen CTC RT-qDx assay was used to analyze the mRNA expression levels of six CTC-specific markers including EpCAM, CK19, HER2, Ki67, hTERT, and vimentin with a total of 692 peripheral whole blood samples from 221 breast cancer patients and 376 healthy individuals.

RESULTS

This assay showed high specificity with multiple markers; none of the healthy controls were detected positive, whereas 21.7 and 14 % of breast cancer patients were positive for EpCAM and CK19, respectively. Of the 221 breast cancer patients, 84 (38 %), 46 (20.8 %), 83 (37.6 %), and 39 (17.6 %) were positively for HER2, Ki67, hTERT, and vimentin mRNA, respectively. Of the 84 patients who were HER2 positive, nine (4 %) were also positive for EpCAM, CK19, Ki67, hTERT, and vimentin. Of the 139 breast cancer patients who were HER2 negative, 65 (29.1 %) were negative for EpCAM, CK19, Ki67, hTERT, and vimentin. Furthermore, the EpCAM-positive population decreased from 21.5 to 8.3 % after completion of anti-tumor treatment (TP4). Similarly, the CK19, HER2, hTERT, and vimentin positives also decreased from 13.9 to 9.5 %, from 37.7 to 21.4 %, from 37.2 to 33.3 %, and from 17.5 to 14.3 %, respectively, after completion of anti-tumor treatment. In contrast, the Ki67 positives increased from 20.6 to 41.7 % after completion of anti-tumor treatment.

CONCLUSIONS

mRNA overexpression of six CTC-specific markers was detected by the CircleGen CTC RT-qDx assay with high specificity, and the obtained mRNA expression levels of CTC-specific markers might provide useful criteria to select appropriate anti-tumor treatment for breast cancer patients.

Biomarkers in Patients with Metastatic Breast Cancer and the PRAEGNANT Study Network

Progress has been made in the treatment of metastatic breast cancer in recent decades, but very few therapies use patient or tumor-specific characteristics to tailor individualized treatment. More than ten years after the publication of the reference human genome sequence, analysis methods have improved enormously, fostering the hope that biomarkers can be used to individualize therapies and offer precise treatment based on tumor and patient characteristics. Biomarkers at every level of the system (genetics, epigenetics, gene expression, micro-RNA, proteomics and others) can be used for this. This has led to changes in clinical study designs, with drug developments often only focusing on small or very small subgroups of patients and tumors. The screening and registration of patients and their molecular tumor data has therefore become very important for the successful completion of clinical studies. This new form of medicine presents particular challenges for patients and physicians. Even in this new age of genome-wide analysis, the focus should still be on the patients' quality of life. This review summarizes recent developments and describes how the PRAEGNANT study network manages the aforementioned medical challenges and changes to create a professional infrastructure for patients and physicians.

Breast Cancer Update 2014 - Focus on the Patient and the Tumour

The therapy for patients with breast cancer has developed markedly in the past ten years. Our understanding of the molecular biology of tumours and the characteristics of the patients has shaped the recent advances. In this review we present the latest knowledge about the therapy for breast cancer. There are new tests and options not only in the field of anti-HER2 therapy but also in the management of triple negative and hormone receptor-positive patients. Comprehension of prognosis and therapeutic response to chemotherapies is little by little helping to define patient groups who will not respond to chemotherapy or who do not need treatment because their prognosis is extremely good. In the field of anti-HER2 therapy, work is continuing on the development of drugs suitable for and able to overcome trastuzumab resistance. For hormone receptor-positive cancers, we now have a better understanding of which therapy groups will benefit from which anti-endocrine drugs, and which will be able to overcome a possible resistance (treatment of the PI3K pathways, inhibition of the cell cycle). Molecular tests are still being evaluated with regard to the clinical situations in which they may have the greatest relevance for therapeutic decision-making; however, evidence is also increasing as to the fields in which good predictions for the prognosis can be obtained. On the whole, more work is needed to promote our understanding of the new developments in diagnostics and therapy and to involve both physicians and patients equally in the procedures.

Mucins and Cytokeratins as Serum Tumor Markers in Breast Cancer

Structural and functional characteristics of mucins and cytokeratins are shortly described. Thereafter, those commonly used in breast cancer as serum tumor markers are considered. First CA15.3, MCA, CA549, CA27.29 mucins and CYFRA21.1, TPA, TPS cytokeratins alone or in association have been examined in different stages and conditions. Then their usefulness in monitoring disease-free breast cancer patients is evaluated. The central role of the established cut-off and critical change, the "early" treatment of recurrent disease and the potential benefit in survival are other issues that have been highlighted and discussed. The successive sections and subsections deal with the monitoring of advanced disease. In them, the current recommendations and the principal findings on using the above mentioned mucins and cytokeratins have been reported. A computer program for interpreting consecutive measurements of serum tumor markers also has been illustrated. The final part of the chapter is devoted to mucins and cytokeratins as markers of circulating and disseminated tumor cells and their usefulness for prognosis.

Circulating tumor cell analysis in metastatic triple-negative breast cancers

PURPOSE

Recent developments in rare-cell technology have led to improved blood-based assays that allow for the reliable detection, enumeration, and more recently, genomic profiling of circulating tumor cells (CTC). We evaluated two different approaches for enumeration of CTCs in a prospective therapeutic study of patients with metastatic triple-negative breast cancer (TNBC).

EXPERIMENTAL DESIGN

The CellSearch system, a commercially available and U.S. Food and Drug Administration (FDA)-cleared assay for CTC enumeration, and IE/FC, an alternative method using EPCAM-based immunomagnetic enrichment and flow cytometry that maintains cell viability, were used to enumerate CTCs in the blood of patients with metastatic TNBC. CTC numbers were assessed at baseline and 7 to 14 days after initiation of therapy with cetuximab ± carboplatin in a phase II multicenter clinical trial (TBCRC 001).

RESULTS

CTC numbers from two methods were significantly correlated at baseline (r = 0.62) and at 7 to 14 days (r = 0.53). Baseline CTCs showed no association with time-to-progression (TTP), whereas CTCs at 7 to 14 days were significantly correlated with TTP (CellSearch P = 0.02; IE/FC P = 0.03). CTCs at both time points were significantly associated with overall survival (OS) [CellSearch: baseline (P = 0.0001) and 7 to 14 days (P < 0.0001); IE/FC: baseline (P = 0.0009) and 7 to 14 days (P = 0.0086)].

CONCLUSIONS

Our findings demonstrate that CTC enumeration by two different assays was highly concordant. In addition, results of both assays were significantly correlated with TTP and OS in patients with TNBC. The IE/FC method is also easily adapted to isolation of pure populations of CTCs for genomic profiling.

Detection of circulating tumor cells in patients with breast cancer using the quantitative RT-PCR assay for monitoring of therapy efficacy

Circulating tumor cells (CTCs) are an independent prognostic factor for patients with breast cancer. However, the role of CTCs in early breast cancer management is not yet clearly defined. The aim of this study was to isolate and characterize CTCs in blood sample of a breast cancer patient as a biomarker for monitoring treatments efficacy. In this study, 692 blood samples from 221 breast cancer patients and 376 healthy individuals was used to detect CTCs with multiple markers including epithelial cell adhesion molecule (EpCAM), cytokeratin (CK) 19, human epidermal growth factor (HER) 2, Ki67, human telomerase reverse transcriptase (hTERT), and vimentin using quantitative reverse transcription PCR (RT-qPCR). A total of 153 (69.2%) blood samples of 221 patients with breast cancer were found to be positive for at least one of the cancer-associated marker gene before treatment. After chemotherapy, no CTCs were found in 28 (33.3%) of the 84 blood samples analyzed for the presence of CTCs using the RT-qPCR, whereas 56 (66.7%) blood samples were still found to be positive for at least one of the markers. After completing the therapy, the CTC positivity rate decreased to 7 (20.6%) in the neoadjuvant group, whereas this increased to 7 (14%) cases in the adjuvant group. There was no statistically significant relationship between TNM stage and detection of CTC-related markers. Data from this study suggest that RT-qPCR assay for the detection of CTC markers might be useful in selecting appropriate therapeutics and for monitoring treatment efficacy in breast cancer patients.

[Circulating tumor cells: cornerstone of personalized medicine]

Cancer treatment has evolved toward personalized medicine. It is mandatory for clinicians to ascertain tumor biological features in order to optimize patients' treatment. Identification and characterization of circulating tumor cells demonstrated a prognostic value in many solid tumors. Here, we describe the main technologies for identification and characterization of circulating tumor cells and their clinical application in gynecologic and breast cancers.

Circulating tumor cells in breast cancer

Circulating tumor cell (CTC) measurement in peripheral blood of patients with breast cancer offers prognostic information. In this review, we will try to identify evidence that could be used for prognosis, predictive power to draw this tool to clinical utility. We reviewed 81 manuscripts, and categorized those in discovery datasets, prognostic factors in metastatic breast cancer, identification of clinical utility in early breast cancer and in novel approaches. With each patient responding differently to chemotherapy, more efficient markers would improve clinical outcome. Current CTC diagnostic techniques use epithelial markers predominantly; however, the most appropriate method is the measurement of circulating DNA. It has been hypothesized that micrometastasis occurs early in the development of tumors. That implies the presence of CTCs in nonmetastatic setting. The origin of stimulus for malignant transformation is yet unknown. The role of microenvironment as a stimulus is also being investigated. It has been shown that CTCs vary in numbers with chemotherapy. The markers, which are followed-up in the primary tumors, are also being studied on the CTCs. There is discordance of the human epidermal growth factor receptor-2 status between the primary tumor and CTCs. This review summarizes our current knowledge about the CTCs. With genetic profiling and molecular characterization of CTCs, it is possible to overcome the diagnostic difficulties. Evidence for clinical utility of CTC as prognostic and predictive marker is increasing. Appropriate patient stratification according to CTC determination among other tests, would make personalized cancer therapy more feasible.