Circulating tumor cells: the 'leukemic phase' of solid cancers

Simultaneous and selective isolation of multiple subpopulations of rare cells from peripheral blood using ensemble-decision aliquot ranking (eDAR)

Rare cells, such as circulating tumor cells (CTCs), can be heterogeneous. The isolation and identification of rare cells with different phenotypes is desirable, for clinical and biological applications. However, CTCs exist in a complex biological environment, which complicates the isolation and identification of particular subtypes. To address this need, we re-designed our ensemble-decision aliquot ranking (eDAR) system to detect, isolate, and study two subpopulations of rare cells in the same microchip. With this dual-capture eDAR device, we simultaneously and selectively isolated two subsets of CTCs from the same blood sample: One set expressed epithelial markers and the other had mesenchymal characteristics. We could apply other selection schemes with different sorting logics to isolate the two subpopulations on demand. The average recovery rate for each subpopulation was higher than 88% with a nearly 100% selectivity of the targeted cells; the throughput was 50 μL min(-1).

Translational potential of cancer stem cells: A review of the detection of cancer stem cells and their roles in cancer recurrence and cancer treatment

Cancer stem cells (CSCs) are a subpopulation of cancer cells with many clinical implications in most cancer types. One important clinical implication of CSCs is their role in cancer metastases, as reflected by their ability to initiate and drive micro and macro-metastases. The other important contributing factor for CSCs in cancer management is their function in causing treatment resistance and recurrence in cancer via their activation of different signalling pathways such as Notch, Wnt/β-catenin, TGF-β, Hedgehog, PI3K/Akt/mTOR and JAK/STAT pathways. Thus, many different therapeutic approaches are being tested for prevention and treatment of cancer recurrence. These may include treatment strategies targeting altered genetic signalling pathways by blocking specific cell surface molecules, altering the cancer microenvironments that nurture cancer stem cells, inducing differentiation of CSCs, immunotherapy based on CSCs associated antigens, exploiting metabolites to kill CSCs, and designing small interfering RNA/DNA molecules that especially target CSCs. Because of the huge potential of these approaches to improve cancer management, it is important to identify and isolate cancer stem cells for precise study and application of prior the research on their role in cancer. Commonly used methodologies for detection and isolation of CSCs include functional, image-based, molecular, cytological sorting and filtration approaches, the use of different surface markers and xenotransplantation. Overall, given their significance in cancer biology, refining the isolation and targeting of CSCs will play an important role in future management of cancer.

Circulating tumor cells: a multifunctional biomarker

One of the most promising developments in translational cancer medicine has been the emergence of circulating tumor cells (CTC) as a minimally invasive multifunctional biomarker. CTCs in peripheral blood originate from solid tumors and are involved in the process of hematogenous metastatic spread to distant sites for the establishment of secondary foci of disease. The emergence of modern CTC technologies has enabled serial assessments to be undertaken at multiple time points along a patient's cancer journey for pharmacodynamic (PD), prognostic, predictive, and intermediate endpoint biomarker studies. Despite the promise of CTCs as multifunctional biomarkers, there are still numerous challenges that hinder their incorporation into standard clinical practice. This review discusses the key technical aspects of CTC technologies, including the importance of assay validation and clinical qualification, and compares existing and novel CTC enrichment platforms. This article discusses the utility of CTCs as a multifunctional biomarker and focuses on the potential of CTCs as PD endpoints either directly via the molecular characterization of specific markers or indirectly through CTC enumeration. We propose strategies for incorporating CTCs as PD biomarkers in translational clinical trials, such as the Pharmacological Audit Trail. We also discuss issues relating to intrapatient heterogeneity and the challenges associated with isolating CTCs undergoing epithelial-mesenchymal transition, as well as apoptotic and small CTCs. Finally, we envision the future promise of CTCs for the selection and monitoring of antitumor precision therapies, including applications in single CTC phenotypic and genomic profiling and CTC-derived xenografts, and discuss the promises and limitations of such approaches. See ALL articles in this CCR focus section, "Progress in pharmacodynamic endpoints."

Circulating melanoma cells in the diagnosis and monitoring of melanoma: an appraisal of clinical potential

Circulating melanoma cells (CMCs) are thought to be the foundation for metastatic disease, which makes this cancer especially lethal. Cancer cells contained in the primary tumor undergo genotypic and phenotypic changes leading to an epithelial-to-mesenchymal transition, during which numerous changes occur in signaling pathways and proteins in the cells. CMCs are then shed off or migrate from the primary tumor and intravasate the vasculature system. A few CMCs are able to survive in the circulation through expression of a variety of genes and also by evading immune system recognition to establish metastases at distant sites after extravasating from the vessels. The presence of CMCs in the blood of a melanoma patient can be used for disease staging, predicting metastasis development, and evaluating the efficacy of therapeutic agents. Overall survival and disease-free duration can also be correlated with the presence of CMCs. Finally, analysis of CMCs for druggable therapeutic gene targets could lead to the development of personalized treatment regimens to prevent metastasis. Thus, the study of CMCs shows promise for the detection, staging, and monitoring of disease treatment, as well as for determination of prognosis and predicting overall disease-free survival. These are the areas reviewed in this article.

SERS-fluorescence joint spectral encoded magnetic nanoprobes for multiplex cancer cell separation

A new kind of cancer cell separation method is demonstrated, using surface-enhanced Raman scattering (SERS) and fluorescence dual-encoded magnetic nanoprobes. The designed nanoprobes can realize SERS-fluorescence joint spectral encoding (SFJSE) and greatly improve the multiplexing ability. The nanoprobes have four main components, that is, the magnetic core, SERS generator, fluorescent agent, and targeting antibody. These components are assembled with a multi-layered structure to form the nanoprobes. Specifically, silica-coated magnetic nanobeads (MBs) are used as the inner core. Au core-Ag shell nanorods (Au@Ag NRs) are employed as the SERS generators and attached on the silica-coated MBs. After burying these Au@Ag NRs with another silica layer, CdTe quantum dots (QDs), that is, the fluorescent agent, are anchored onto the silica layer. Finally, antibodies are covalently linked to CdTe QDs. SFJSE is fulfilled by using different Raman molecules and QDs with different emission wavelengths. By utilizing four human cancer cell lines and one normal cell line as the model cells, the nanoprobes can specifically and simultaneously separate target cancer cells from the normal ones. This SFJSE-based method greatly facilitates the multiplex, rapid, and accurate cancer cell separation, and has a prosperous potential in high-throughput analysis and cancer diagnosis.

All-in-one centrifugal microfluidic device for size-selective circulating tumor cell isolation with high purity

Circulating tumor cells (CTCs) have gained increasing attention owing to their roles in cancer recurrence and progression. Due to the rarity of CTCs in the bloodstream, an enrichment process is essential for effective target cell characterization. However, in a typical pressure-driven microfluidic system, the enrichment process generally requires complicated equipment and long processing times. Furthermore, the commonly used immunoaffinity-based positive selection method is limited, as its recovery rate relies on EpCAM expression of target CTCs, which shows heterogeneity among cell types. Here, we propose a centrifugal-force-based size-selective CTC isolation platform that can isolate and enumerate CTCs from whole blood within 30 s with high purity. The device was validated using the MCF-7 breast cancer cell line spiked in phosphate-buffered saline and whole blood, and an average capture efficiency of 61% was achieved, which is typical for size-based filtration. The capture efficiency for whole blood samples varied from 44% to 84% under various flow conditions and dilution factors. Under the optimized operating conditions, a few hundred white blood cells per 1 mL of whole blood were captured, representing a 20-fold decrease compared to those obtained using a commercialized size-based CTC isolation device. In clinical validation, normalized CTC counts varied from 10 to 60 per 7.5 mL of blood from gastric and lung cancer patients, yielding a detection rate of 50% and 38%, respectively. Overall, our CTC isolation device enables rapid and label-free isolation of CTCs with high purity, which should greatly improve downstream molecular analyses of captured CTCs.

Transurethral bladder tumor resection can cause seeding of cancer cells into the bloodstream

PURPOSE

Transurethral bladder tumor resection is the initial diagnostic procedure for bladder cancer. Hypothetically tumor resection could induce seeding of cancer cells into the circulation and subsequent metastatic disease. In this study we ascertain whether transurethral bladder tumor resection induces measurable seeding of cancer cells into the vascular system.

MATERIALS AND METHODS

Patients newly diagnosed with suspected invasive bladder cancer and planned for transurethral resection of bladder tumor in 2012 to 2013 were enrolled in the study. Before transurethral bladder tumor resection a vascular surgeon placed a venous catheter in the inferior vena cava via the femoral vein. Blood samples were drawn before and during the resection from the inferior vena cava and a peripheral vein, and analyzed for circulating cancer cells using the CellSearch® system. The number of circulating tumor cells identified was compared in preoperative and intraoperative blood samples.

RESULTS

The circulating tumor cell data on 16 eligible patients were analyzed. In 6 of 7 positive inferior vena cava samples (86%) the number of circulating tumor cells was increased intraoperatively (28 vs 9, 28 vs 0, 28 vs 5, 3 vs 0, 4 vs 0, 1 vs 0), and results were similar, although less conclusive, for the corresponding peripheral vein samples.

CONCLUSIONS

Our study confirms that tumor cells can be released into the circulation during transurethral bladder tumor resection. It is currently unknown whether this will increase the risk of metastatic disease.

The advantage of circulating tumor cells over serum carcinoembryonic antigen for predicting treatment responses in rectal cancer

AIM

The objective of this study was to investigate the clinical significance of circulating tumor cells (CTCs) on the evaluation and prediction of treatment responses in rectal cancer patients compared with serum carcinoembryonic antigen (CEA).

MATERIALS & METHODS

Both CTCs and CEA levels of 103 rectal cancer patients (66 with stage II-III and 37 with recurrence or metastasis) were analyzed before and after chemoradiotherapy. CTCs were detected using EpCAM magnetic bead-based enrichment combined with cytometric identification.

RESULTS

CTCs were detected in all patients while no tumor cells were found in healthy controls. CTC levels in metastatic patients were significantly higher than those with recurrence or stage II-III rectal cancer. There is a close relationship between CTC levels and treatment outcomes but serum CEA did not have any correlation.

CONCLUSION

CTCs are promising markers for the evaluation and prediction of treatment responses in rectal cancer patients, superior to the conventional tumor marker CEA.

Multiscale immunomagnetic enrichment of circulating tumor cells: from tubes to microchips

We review the rare cancer cell sorting technologies, with a focus on multiscale immunomagnetic approaches. Starting from the conventional magnetic activated cell sorting system, we derive the scaling laws of immunomagnetic assay and justify the recent trend of using downscaled systems for CTC studies. Furthermore, we introduce recent work on combining the immunomagnetic assay with microfluidic technology for enhanced separation. We summarize different types of in-channel micro-magnetic structures that can further increase the local magnetic field without lowering the system throughput. Related design concepts, principles, and microfabrication techniques are presented and evaluated.

Chronic obstructive pulmonary disease in stage I non-small cell lung cancer that underwent anatomic resection: the role of a recurrence promoter

BACKGROUND

Despite the use of anatomic resection, the post-surgical recurrence rate remains high in early-stage non-small cell lung cancer (NSCLC). Chronic inflammation plays a role in the mechanism that promotes tumor initiation. This study aimed to investigate the association between recurrence outcome and chronic inflammation-related co-morbidities in early-stage resected NSCLC.

METHODS

A review of medical records for recurrence outcome and co-morbidities, in terms of chronic obstructive pulmonary disease (COPD), DM, asthma and cardiovascular diseases, was performed with 181 patients with stage I NSCLC that underwent anatomic resection.

RESULTS

Subjects with T descriptors as T2a disease (49.5 vs. 28.0%, p < 0.05) and the presence of COPD (42.4 vs. 20.7%, p < 0.01) had a higher risk of tumor recurrence. Univariate analysis for recurrence-free survival showed T descriptor as T2a (21.5 months vs. NR, p < 0.05) and the presence of COPD (20.5 months vs. NR, p < 0.01) as significant factors predicting reduced survival. The presence of COPD (HR: 1.98; 95% CI, 1.29-.02, p < 0.01) and T descriptor as T2a (HR: 2.01; 95% CI, 1.04-3.91, p < 0.05) remain independent predictors of reduced recurrence-free survival in the Cox regression model. Patients with COPD were at higher risk of brain recurrence (OR: 7.88; 95% CI, 1.50-41.3, p < 0.01). In contrast, patients without COPD showed a tendency toward recurrence in bone and liver (OR: 4.13; 95% CI, 1.08-15.8, p = 0.05).

CONCLUSION

Subjects with COPD and T2a disease had a higher risk of recurrence. The role of COPD as a recurrence promoter merits further prospective investigation.

Detection methods of circulating tumor cells in cutaneous melanoma: a systematic review

The vast majority of melanoma-related deaths are due to disseminated malignancy. Many treated patients who are clinically disease-free will go on to relapse. Therefore, new prognostic tools must be developed to better assess metastatic potential and assist in patient management. Circulating tumor cells are a widely studied metastatic biomarker with promising prognostic utility, as the shedding of cells from the primary tumor into peripheral blood is a necessary step in disease dissemination. An assortment of technologies and techniques has been developed to isolate and detect circulating melanoma cells (CMCs), but a standardized method is yet to be established. It is the aim of this study to systematically review the diverse enrichment and detection methods of circulating tumor cells in cutaneous melanoma. A literature search yielded 351 articles, of which 74 were deemed eligible according to inclusion criteria, the primary requirement being the reporting of patient CMC positivity status stratified by the stage of melanoma. Pertinent studies were used to evaluate the advantages and disadvantages of each method. Additionally, we calculated the sensitivity and specificity of seven common melanoma-associated markers based on the available literature.

Isolation and mutational analysis of circulating tumor cells from lung cancer patients with magnetic sifters and biochips

Detection and characterization of circulating tumor cells (CTCs) may reveal insights into the diagnosis and treatment of malignant disease. Technologies for isolating CTCs developed thus far suffer from one or more limitations, such as low throughput, inability to release captured cells, and reliance on expensive instrumentation for enrichment or subsequent characterization. We report a continuing development of a magnetic separation device, the magnetic sifter, which is a miniature microfluidic chip with a dense array of magnetic pores. It offers high efficiency capture of tumor cells, labeled with magnetic nanoparticles, from whole blood with high throughput and efficient release of captured cells. For subsequent characterization of CTCs, an assay, using a protein chip with giant magnetoresistive nanosensors, has been implemented for mutational analysis of CTCs enriched with the magnetic sifter. The use of these magnetic technologies, which are separate devices, may lead the way to routine preparation and characterization of "liquid biopsies" from cancer patients.

Circulating tumor cell enrichment based on physical properties

The metastatic dissemination and spread of malignant circulating tumor cells (CTCs) accounts for more than 90% of cancer-related deaths. CTCs detach from a primary tumor, travel through the circulatory system, and then invade and proliferate in distant organs. The detection of CTCs from blood has been established for prognostic monitoring and is predictive of patient outcome. Analysis of CTCs could enable the means for early detection and screening in cancer, as well as provide diagnostic access to tumor tissues in a minimally invasive way. The fundamental challenge with analyzing CTCs is the fact that they occur at extremely low concentrations in blood, on the order of one out of a billion cells. Various technologies have been proposed to isolate CTCs for enrichment. Here we focus on antigen-independent approaches that are not limited by specific capture antibodies. Intrinsic physical properties of CTCs, including cell size, deformability, and electrical properties, are reviewed, and technologies developed to exploit them for enrichment from blood are summarized. Physical enrichment technologies are of particular interest as they have the potential to increase yield and enable the analysis of rare CTC phenotypes that may not be otherwise obtained.

New generation of ensemble-decision aliquot ranking based on simplified microfluidic components for large-capacity trapping of circulating tumor cells

Ensemble-decision aliquot ranking (eDAR) is a sensitive and high-throughput method to analyze circulating tumor cells (CTCs) from peripheral blood. Here, we report the next generation of eDAR, where we designed and optimized a new hydrodynamic switching scheme for the active sorting step in eDAR, which provided fast cell sorting with an improved reproducibility and stability. The microfluidic chip was also simplified by incorporating a functional area for subsequent purification using microslits fabricated by standard lithography method. Using the reported second generation of eDAR, we were able to analyze 1 mL of whole-blood samples in 12.5 min, with a 95% recovery and a zero false positive rate (n = 15).

High-performance size-based microdevice for the detection of circulating tumor cells from peripheral blood in rectal cancer patients

Since individualized therapy becomes more and more important in the treatment of rectal cancer, an accurate and effective approach should be established in the clinical settings to help physicians to make their decisions. Circulating tumor cells (CTCs), originated from either primary or metastatic cancer, could provide important information for diagnosis and monitoring of cancer. However, the implication and development of CTCs are limited due to the extreme rarity of these tumor cells. In this study we fabricated a simple and high-performance microfluidic device, which exploited numerous filtered microchannels in it to enrich the large-sized target tumor cells from whole blood. A very high CTC capture efficiency (average recovery rate: 94%) was obtained in this device at the optimum flow rate of 0.5 mL/h and channel height of 5 µm. Additionally, we used this device for detecting CTCs in 60 patients with rectal cancer. The CTC counts of rectal cancer patients were significantly higher than those in healthy subjects. Furthermore, the CTC counts detected by this device were significantly higher than those by EpCAM bead-based method for rectal cancer patients with various stage. Especially, for localized rectal cancer patients, the positive rates of samples with more than 3 CTCs per 5 mL blood by use of microdevice vs. EpCAM-based ones were 100% vs. 47%, respectively. Thus, this device provides a new and effective tool for accurate identification and measurement of CTCs in patients with rectal cancer, and has broad potential in clinical practice.

Detection and isolation of circulating tumor cells: principles and methods

Efforts to improve the clinical management of several cancers include finding better methods for the quantitative and qualitative analysis of circulating tumor cells (CTCs). However, detection and isolation of CTCs from the blood circulation is not a trivial task given their scarcity and the lack of reliable markers to identify these cells. With a variety of emerging technologies, a thorough review of the exploited principles and techniques as well as the trends observed in the development of these technologies can assist researchers to recognize the potential improvements and alternative approaches. To help better understand the related biological concepts, a simplified framework explaining cancer formation and its spread to other organs as well as how CTCs contribute to this process has been presented first. Then, based on their basic working-principles, the existing methods for detection and isolation of CTCs have been classified and reviewed as nucleic acid-based, physical properties-based and antibody-based methods. The review of literature suggests that antibody-based methods, particularly in conjunction with a microfluidic lab-on-a-chip setting, offer the highest overall performance for detection and isolation of CTCs. Further biological and engineering-related research is required to improve the existing methods. These include finding more specific markers for CTCs as well as enhancing the throughput, sensitivity, and analytic functionality of current devices.

Diagnostic accuracy of circulating tumor cells detection in gastric cancer: systematic review and meta-analysis

BACKGROUND

Circulating tumor cells (CTCs) detection has previously been used for diagnosing gastric cancer. However, the previous studies failed to make an agreement whether the detection of CTCs contributes to the diagnosis of gastric cancer.

METHODS

A systematic review and meta-analysis was performed to evaluate the overall accuracy of CTCs detection for diagnosing gastric cancer. PubMed, Embase and the Wanfang database were searched in all languages published up to Oct 2012. The pooled sensitivity (SEN), specificity (SPE), positive and negative likelihood ratios (PLR and NLR, respectively), diagnostic odds ratio (DOR) and summary receiver operating characteristic (sROC) curve were calculated to evaluate the overall test performance.

RESULTS

Twenty studies were included in this systematic review and meta-analysis. The diagnostic value of CTCs detection for the gastric cancer was calculated to evaluate the overall test performance. The summary estimates of The pooled sensitivity, specificity, positive and negative likelihood ratios, diagnostic odds ratio were 0.42 (95% confidence interval (CI), 0.21-0.67), 0.99 (95% CI, 0.96-1.00), 58.2 (95% CI, 9.8-345.9), 0.58 (95% CI, 0.38-0.89), and 100 (95% CI, 15-663), respectively. The summary receiver operating characteristic curve was 0.97 (95% CI, 0.95-0.98). Deek's funnel plot asymmetry test found no evidence of study publication bias in the current study (P = 0.49).

CONCLUSION

This systematic review suggests that CTCs detection alone cannot be recommended as a screening test for gastric cancer. However, it might be used as a noninvasive method for the confirmation of the gastric cancer diagnosis.

Enrichment, detection and clinical significance of circulating tumor cells

Circulating Tumor Cells (CTCs) are shed from primary or secondary tumors into blood circulation. Accessing and analyzing these cells provides a non-invasive alternative to tissue biopsy. CTCs are estimated to be as few as 1 cell among a few million WBCs and few billion RBCs in 1 ml of patient blood and are rarely found in healthy individuals. CTCs are FDA approved for prognosis of the major cancers, namely, Breast, Colon and Prostate. Currently, more than 400 clinical trials are ongoing to establish their clinical significance beyond prognosis, such as, therapy selection and companion diagnostics. Understanding the clinical relevance of CTCs typically involves isolation, detection and molecular characterization of cells, ideally at single cell level. The need for highly reliable, standardized and robust methodologies for isolating and analyzing CTCs has been widely expressed by clinical thought leaders. In the last decade, numerous academic and commercial technology platforms for isolation and analysis of CTCs have been reported. A recent market report highlighted the presence of more than 100 companies offering products and services related to CTCs. This review aims to capture the state of the art and examines the technical merits and limitations of contemporary technologies for clinical use.

Kinase activation in circulating cells: opportunities for biomarkers for diagnosis and therapeutic monitoring

A clinically useful tool to assay phosphorylation-dependent signaling in circulating cells has the potential to provide a wealth of information about a patient's health, including information unavailable by any other method. Patterns of kinase activation, such as the abnormal signaling characteristic of myeloproliferative disorders, may offer highly specific biomarkers for diagnosis or monitoring the efficacy of therapeutics. For assays of kinase activity in circulating leukocytes to be standardized, let alone made practical for the clinic, numerous technical hurdles must be overcome. In this review the current status of analysis of kinase signaling in circulating cells and recent progress in biomarker discovery and validation is discussed. Looking forward, the potential value of signaling patterns as complex biomarkers and the resulting need for future development of robust, multiplexed assays of kinase activation is addressed.

Anterior gradient 2 (AGR2): blood-based biomarker elevated in metastatic prostate cancer associated with the neuroendocrine phenotype

BACKGROUND

Anterior gradient 2 (AGR2) is associated with metastatic progression in prostate cancer cells as well as other normal and malignant tissues. We investigated AGR2 expression in patients with metastatic prostate cancer.

METHODS

Blood was collected from 44 patients with metastatic prostate cancer separated as: castration sensitive prostate cancer (CSPC, n = 5); castration resistant prostate cancer (CRPC, n = 36); and neuroendocrine-predominate CRPC defined by PSA ≤ 1 ng/ml in the presence of wide-spread metastatic disease (NE-CRPC, n = 3). AGR2 mRNA levels were measured with RT-PCR in circulating tumor cell (CTC)-enriched peripheral blood. Plasma AGR2 levels were determined via ELISA assay. AGR2 expression was modulated in prostate cancer cell lines using plasmid and viral vectors.

RESULTS

AGR2 mRNA levels are elevated in CTCs and strongly correlated with CTC enumeration. Plasma AGR2 levels are elevated in all sub-groups. AGR2 levels vary independently to PSA and change in some patients in response to androgen-directed and other therapies. Plasma AGR2 levels are highest in the NE-CRPC sub-group. A correlation between AGR2, chromagranin A (CGA), and neuron-specific enolase (NSE) expression is demonstrated in prostate cancer cell lines.

CONCLUSIONS

We conclude that AGR2 expression is elevated at the mRNA and protein level in patients with metastatic prostate cancer. In particular, we find that AGR2 expression is associated features consistent with neuroendocrine, or anaplastic, prostate cancer, exemplified by an aggressive clinical phenotype without elevation in circulating PSA levels. Further studies are warranted to explore the mechanistic and prognostic implications of AGR2 expression in this patient population.

Evaluation of treatment response for breast cancer: are we entering the era of "biological complete remission"?

Breast cancer is one of the most common malignancies in women. The post-operative recurrence and metastasis are the leading causes of breast cancer-related mortality. In this study, we tried to explore the role of circulating tumor cell (CTC) detection combination PET/CT technology evaluating the prognosis and treatment response of patients with breast cancer; meanwhile, we attempted to assess the concept of "biological complete remission" (bCR) in this regard. A 56-year-old patient with breast cancer (T(2)N(1)M(1), stage IV left breast cancer, with metastasis to axillary lymph nodes and lungs) received 6 cycles of salvage treatment with albumin-bound paclitaxel plus capecitabine and trastuzumab. Then, she underwent CTC detection and PET/CT for efficacy evaluation. CTC detection combination PET/CT is useful for the evaluation of the biological efficacy of therapies for breast cancer. The bCR of the patient appeared earlier than the conventional clinical imaging complete remission and promised the histological (pathological) complete remission. The integrated application of the concepts including bCR, imageological CR, and histological CR can achieve the early and accurate assessment of biological therapeutic reponse and prognosis of breast cancer.

Fluorescence detection and depletion of T47D breast cancer cells from human mononuclear cell-enriched blood preparations by photodynamic treatment: Basic in vitro experiments towards the removal of circulating tumor cells

OBJECTIVES

A major obstacle for permanent cancer eradication is the persistence of circulating tumor cells (CTCs) in blood, which often escape radio- or chemotherapy. Currently no efficient strategy to remove CTCs from peripheral blood in order to lower the risk of metastases or tumor recurrence exists. Photodynamic treatment (PDT) using aminolevulinic acid (ALA) induced protoporphyrin IX (PPIX) as photosensitizer offers an innovative approach to overcome this problem. This study aims at providing basic evidence towards fluorescence detection and photodynamic depletion of scattered cancer cells from blood preparations.

METHODS

The breast cancer cell line T47D, endothelial GP8 cells, red blood cells (RBCs) and peripheral blood mononuclear cells (MNCs) have been tested for ALA-induced formation kinetics of PPIX by flow cytometry and microplate fluorescence analysis. The influence of the presence of RBCs on the PPIX-accumulation in cancer cells was evaluated by flow cytometry; the efficacy of PDT on cancer cells and MNCs has been tested by resazurin assay. Mixtures of T47D and GP8 cells and MNCs spiked with cancer cells were tested to determine the limit of fluorescence detection by flow cytometry and antibody co-staining.

RESULTS

T47D cells accumulated significantly higher PPIX-amounts after ALA-incubation than any other cell type tested. The presence of RBCs had no impact on PPIX-formation in T47D cells. Experiments towards the fluorescence detection of cancer cells in blood revealed that the sensitivity of this method is yet limited. Viability testing after PDT showed that cancer cells where almost completely eradicated after illumination whereas MNCs were almost spared.

CONCLUSION

We clearly demonstrate in vitro tumor cell selectivity of PPIX-accumulation over endothelial cells, MNCs and RBCs. Breast cancer cells are efficiently killed by PDT with minor depletion of MNCs. Our findings provide a basis for the PDT of blood samples for a future depletion of CTCs.

Using circulating tumor cells as a prognostic indicator in metastatic castration-resistant prostate cancer

A more reliable tumor marker is needed as a prognostic indicator in metastatic castration-resistant prostate cancer. Circulating tumor cells (CTCs) are cells that have broken away from a tumor and flow in the bloodstream. Evidence has indicated that the presence of CTCs in the peripheral blood of men with solid malignancies correlates with clinical outcomes. When the CTC number is reduced to fewer than five cells per 7.5 ml of blood, survival outcomes often improve. The relationship between the number of CTCs and prognosis has the potential to influence treatment decisions. Therefore, oncology nurses and practitioners must evaluate the scientific evidence, understand the clinical implications, and realize the impact CTC counts may have on practice to effectively communicate the CTC results to a patient. In addition, oncology nurses and practitioners must know that although favorable changes in CTC count are associated with a better prognosis, that alone cannot be used to guide treatment decisions for an individual.

Electrochemiluminescent determination of cancer cells based on aptamers, nanoparticles, and magnetic beads

Herein we report a polymerase chain reaction (PCR)-free electrochemiluminescence (ECL) approach that uses ECL nanoprobes for the determination of cancer cells with high sensitivity. The ECL nanoprobe consists of gold nanoparticles (AuNPs), linker DNA, and tris(2,2'-bipyridyl)ruthenium (TBR)-labeled signal DNA. The linker DNA and signal DNA were modified on the surface of the AuNPs through Au-S bonds. The linker DNA can partly hybridize with the aptamers of cancer cells loaded onto the magnetic beads (MB1) to construct the magnetic biocomplexes. In the presence of the cancer cells, the aptamers conjugated with the cancer cells with higher affinity. The ECL nanoprobe was released from the biocomplexes and subsequently hybridized with the capture DNA loaded onto another magnetic bead (MB2) to form the magnetic nanocomposite. The nanocomposites can be easily separated and firmly attached to an electrode on account of their excellent magnetic properties. The ECL intensity of the TBR loaded onto the nanocomposites directly reflected the amount of cancer cells. By using cell lines of Burkitt's lymphoma (Ramos cells) as a model, the ECL response was proportional to the cell concentration in the range from 5 to 100 cells ml(-1); a limit of detection as low as 5 cells ml(-1) of Ramos cells could be achieved. The proposed method described here is ideal for the diagnosis of cancers due to its high sensitivity, simplicity, and low cost.

Cascade signal amplification strategy for the detection of cancer cells by rolling circle amplification and nanoparticles tagging

A cascade signal amplification strategy was proposed for detection of cancer cells at ultralow concentration by combining the rolling circle amplification (RCA) technique with oligonucleotide functionalized nanoparticles (NPs), and anodic stripping voltammetric detection. This flexible biosensing system exhibited high sensitivity and specificity with the detection limits of 10 Ramos cells mL(-1).

Accurate detection of carcinoma cells by use of a cell microarray chip

Background

Accurate detection and analysis of circulating tumor cells plays an important role in the diagnosis and treatment of metastatic cancer treatment.

Methods and Findings

A cell microarray chip was used to detect spiked carcinoma cells among leukocytes. The chip, with 20,944 microchambers (105 µm width and 50 µm depth), was made from polystyrene; and the formation of monolayers of leukocytes in the microchambers was observed. Cultured human T lymphoblastoid leukemia (CCRF-CEM) cells were used to examine the potential of the cell microarray chip for the detection of spiked carcinoma cells. A T lymphoblastoid leukemia suspension was dispersed on the chip surface, followed by 15 min standing to allow the leukocytes to settle down into the microchambers. Approximately 29 leukocytes were found in each microchamber when about 600,000 leukocytes in total were dispersed onto a cell microarray chip. Similarly, when leukocytes isolated from human whole blood were used, approximately 89 leukocytes entered each microchamber when about 1,800,000 leukocytes in total were placed onto the cell microarray chip. After washing the chip surface, PE-labeled anti-cytokeratin monoclonal antibody and APC-labeled anti-CD326 (EpCAM) monoclonal antibody solution were dispersed onto the chip surface and allowed to react for 15 min; and then a microarray scanner was employed to detect any fluorescence-positive cells within 20 min. In the experiments using spiked carcinoma cells (NCI-H1650, 0.01 to 0.0001%), accurate detection of carcinoma cells was achieved with PE-labeled anti-cytokeratin monoclonal antibody. Furthermore, verification of carcinoma cells in the microchambers was performed by double staining with the above monoclonal antibodies.

Conclusion

The potential application of the cell microarray chip for the detection of CTCs was shown, thus demonstrating accurate detection by double staining for cytokeratin and EpCAM at the single carcinoma cell level.

Mutation analysis of BRAF and KIT in circulating melanoma cells at the single cell level

Background:

The availability of molecular-targeted therapies for the treatment of melanoma has emphasised the need to identify mutations in target genes such as BRAF and KIT. Circulating tumour cells (CTC) are present in the peripheral blood of a significant proportion of cancer patients.

Methods:

High molecular weight melanoma-associated antigen (HMW-MAA) was used to isolate melanoma cells from peripheral blood as it is selectively expressed at high levels on melanomas. The HMW-MAA-positive cells were isolated using immunomagnetic beads. After removing CD45⁺ cells, CTC were identified by staining with MART-1- and gp100-specific antibodies (HMW-MAA⁺, CD45⁻, MART-1/gp100⁺). Single, isolated CTC were then subjected to BRAF and KIT mutational analysis.

Results:

CTC (HMW-MAA⁺, CD45⁻, MART-1/gp100⁺) were isolated from the blood of 11 patients and BRAF and KIT were sequenced in nine and four patients, respectively. The BRAF sequences identified in the CTC were inconsistent with those identified in autologous melanoma tumours in three patients and the KIT sequences were inconsistent in three patients. In addition, polyclonal BRAF mutations were identified in one patient and concomitant mutations in BRAF and KIT were identified in another patient.

Conclusion:

Melanoma cells show clonal heterogeneity. Therefore, CTC genotyping may be crucial for successful molecular-targeted therapy.

Multimarker gene analysis of circulating tumor cells in pancreatic cancer patients: a feasibility study

OBJECTIVE

The aim of this study was to develop an immunomagnetic/real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay and assess its clinical value for the molecular detection of circulating tumor cells (CTCs) in peripheral blood of pancreatic cancer patients.

METHODS

The presence of CTCs was evaluated in 34 pancreatic cancer patients before systemic therapy and in 40 healthy controls, through immunomagnetic enrichment, using the antibodies BM7 and VU1D9 [targeting mucin 1 and epithelial cell adhesion molecule (EpCAM), respectively], followed by real-time RT-PCR analysis of the genes KRT19, MUC1, EPCAM, CEACAM5 and BIRC5.

RESULTS

The developed assay showed high specificity, as none of the healthy controls were found to be positive for the multimarker gene panel. CTCs were detected in 47.1% of the pancreatic cancer patients before the beginning of systemic treatment. Shorter median progression-free survival (PFS) was observed for patients who had at least one detectable tumor-associated transcript, compared with patients who were CTC negative. Median PFS time was 66.0 days [95% confidence interval (CI) 44.8-87.2] for patients with baseline CTC positivity and 138.0 days (95% CI 124.1-151.9) for CTC-negative patients (p = 0.01, log-rank test).

CONCLUSION

Our results suggest that in addition to the current prognostic methods, CTC analysis represents a potential complementary tool for prediction of outcome in pancreatic cancer patients.

Circulating tumor cells measurements in hepatocellular carcinoma

Liver cancer is the fifth most common cancer in men and the seventh in women. During the past 20 years, the incidence of HCC has tripled while the 5-year survival rate has remained below 12%. The presence of circulating tumor cells (CTC) reflects the aggressiveness nature of a tumor. Many attempts have been made to develop assays that reliably detect and enumerate the CTC during the development of the HCC. In this case, the challenges are (1) there are few markers specific to the HCC (tumor cells versus nontumor cells) and (2) they can be used to quantify the number of CTC in the bloodstream. Another technical challenge consists of finding few CTC mixed with million leukocytes and billion erythrocytes. CTC detection and identification can be used to estimate prognosis and may serve as an early marker to assess antitumor activity of treatment. CTC can also be used to predict progression-free survival and overall survival. CTC are an interesting source of biological information in order to understand dissemination, drug resistance, and treatment-induced cell death. Our aim is to review and analyze the different new methods existing to detect, enumerate, and characterize the CTC in the peripheral circulation of patients with HCC.

Managing immunity in resistant cancer patients correlates to survival: results and discussion of a pilot study

Many cancer patients do not die due to impaired organ functions, but as a result of reduced general conditions, such as cachexia, sarcopenia, depression, infections, or stress. Reduced general health may be caused by immune modifying cytokines released from the tumor into the body. Improvement of immunity would not only reduce cancer side effects through inhibiting cytokine release from the tumor into the blood, but also, according to a new hypothesis, modify the cancer stem cells (CSC) in the tumor, which are believed to drive cancer growth and metastasis. We reported previously several investigations with a dietary fermented soy formulation (FSWW08) in cancer patients, where we saw a) strong reduction of cancer symptoms, b) broken resistance to chemotherapy, and c) a strong reduction of chemotherapy's toxic side effects, when taken in combination. This publication reports two new findings from a pilot study with postsurgical, treatment resistant patients conducted over four years. First, neither treatment resistance nor side effects were observed. Second, more patients have survived than expected. The improved health and immunity is detected together with increased CSC differentiation, suggesting lower aggressiveness, which was corroborated by increased gene expressions, particularly of steroidal hormones, MAPkinase, NF-κB, and tumor suppressor factor p53, a typical marker of "stemness" or cell differentiation. Although limited by its small, homogenous sample size, the results of this pilot study illustrate the relationship between CSCs differentiation, and the clinical symptoms of immunity, which influence survival outcomes and raise the clinical potential of measuring CSCs in ovarian, prostate, and breast cancers. The improved survival rates are also seen in larger cohort studies, which show similar gene expression profiles, which were induced by FSWW08 in the treatment resistant cancer patients in this study.

A direct comparison of CellSearch and ISET for circulating tumour-cell detection in patients with metastatic carcinomas

Background:

Circulating tumour cells (CTCs) can provide information on patient prognosis and treatment efficacy. However, there is no universal method to detect CTC currently available. Here, we compared the performance of two CTC detection systems based on the expression of the EpCAM antigen (CellSearch assay) or on cell size (ISET assay).

Methods:

Circulating tumour cells were enumerated in 60 patients with metastatic carcinomas of breast, prostate and lung origins using CellSearch according to the manufacturer's protocol and ISET by studying cytomorphology and immunolabelling with anti-cytokeratin or lineage-specific antibodies.

Results:

Concordant results were obtained in 55% (11 out of 20) of the patients with breast cancer, in 60% (12 out of 20) of the patients with prostate cancer and in only 20% (4 out of 20) of lung cancer patients.

Conclusion:

Our results highlight important discrepancies between the numbers of CTC enumerated by both techniques. These differences depend mostly on the tumour type. These results suggest that technologies limiting CTC capture to EpCAM-positive cells, may present important limitations, especially in patients with metastatic lung carcinoma.

Diagnostic value of circulating tumor cell detection in bladder and urothelial cancer: systematic review and meta-analysis

Background

The diagnostic value and prognostic significance of circulating tumor cell (CTC) detection in patients with bladder cancer is controversial. We performed a meta-analysis to consolidate current evidence regarding the use of CTC detection assays to diagnose bladder and other urothelial cancers and the association of CTC positivity with advanced, remote disease.

Methods

Studies that investigated the presence of CTCs in the peripheral blood of patients with bladder cancer and/or urothelial cancer were identified and reviewed. Sensitivities, specificities, and positive (LR+) and negative likelihood ratios (LR-) of CTC detection in individual studies were calculated and meta-analyzed by random effects model. Overall odds ratio of CTC positivity in patients with advanced disease versus those with organ-confined cancer was also calculated.

Results

Overall sensitivity of CTC detection assays was 35.1% (95%CI, 32.4-38%); specificity, LR+, and LR- was 89.4% (95%CI, 87.2-91.3%), 3.77 (95%CI, 1.95-7.30) and 0.72 (95%CI, 0.64-0.81). CTC-positive patients were significantly more likely to have advanced (stage III-IV) disease compared with CTC-negative patients (OR, 5.05; 95%CI, 2.49-10.26).

Conclusions

CTC evaluation can confirm tumor diagnosis and identify patients with advanced bladder cancer. However, due to the low overall sensitivity, CTC detection assays should not be used as initial screening tests.

Detection of circulating tumor cells: Clinical relevance of a novel metastatic tumor marker

Most cancer-related deaths are caused by the hematogenous spread of cancer cells to distant organs and their subsequent metastasis. During the early stages of the metastatic cascade, cancer cells disseminate from the primary site via the lymphatic vessels and/or by hematogenous routes. Circulating tumor cells (CTCs), cancer cells that have disseminated into the systemic circulation, may be a predictor of poor prognosis in several carcinomas. An understanding of the molecular mechanisms involved in the blood-borne dissemination of cancer cells may help to clarify the process of metastasis and provide a powerful and non-invasive approach for anticancer treatments that are tailored to individual patients.

Continuous separation of breast cancer cells from blood samples using multi-orifice flow fractionation (MOFF) and dielectrophoresis (DEP)

Circulating tumor cells (CTCs) are highly correlated with the invasive behavior of cancer, so their isolations and quantifications are important for biomedical applications such as cancer prognosis and measuring the responses to drug treatments. In this paper, we present the development of a microfluidic device for the separation of CTCs from blood cells based on the physical properties of cells. For use as a CTC model, we successfully separated human breast cancer cells (MCF-7) from a spiked blood cell sample by combining multi-orifice flow fractionation (MOFF) and dielectrophoretic (DEP) cell separation technique. Hydrodynamic separation takes advantage of the massive and high-throughput filtration of blood cells as it can accommodate a very high flow rate. DEP separation plays a role in precise post-processing to enhance the efficiency of the separation. The serial combination of these two different sorting techniques enabled high-speed continuous flow-through separation without labeling. We observed up to a 162-fold increase in MCF-7 cells at a 126 µL min(-1) flow rate. Red and white blood cells were efficiently removed with separation efficiencies of 99.24% and 94.23% respectively. Therefore, we suggest that our system could be used for separation and detection of CTCs from blood cells for biomedical applications.

Biomarkers in cancer micrometastasis: where are we at?

Despite considerable advances in the field of solid tumors, disseminated malignancy remains the cause of the vast majority of cancer-related deaths. In patients with no overt metastasis, early spread of tumor cells is usually undetected by current imaging technologies. In addition, the metastatic process is complex and depends on multiple interactions (crosstalk) of disseminating tumor cells with the individual homeostatic mechanisms, which the tumor cells can usurp. Despite these many variables, a flurry of surrogate biomarkers to detect micrometastasis has been developed in the last decade. These biomarkers open avenues for understanding cancer dormancy and metastasis, have the potential to provide novel therapeutic targets and may help predict outcome and therapeutic decisions at diagnosis and during follow-up of cancer patients. This review focuses on ongoing efforts to unravel metastasis biology, surrogate biomarkers currently investigated to monitor micrometastasis and tools used to identify, quantify and determine their capacity to efficiently establish metastasis.

Clinical significance of CDX2-positive circulating tumour cells in colorectal cancer patients

Background:

Our recent work has shown the feasibility of using a refined immunomagnetic enrichment (IE) assay to detect cytokeratin 20-positive circulating tumour cells (CK20 pCTCs) in colorectal cancer (CRC) patients. We attempted to improve the sensitivity for CRC by detecting another intestinal-type differentiation marker, CDX2 pCTCs, using the same methodology.

Methods:

CDX2 pCTCs were detected in patients with CRC, colorectal adenoma (CAD), benign colorectal diseases (BCD), other common cancers (OCC) and normal subjects (NS). Statistical analysis was used to correlate CDX2 pCTCs to the clinicohistopathological factors, recurrence, metastasis and survival after follow-up for 42 months in CRC patients.

Results:

CDX2 pCTCs were detected in 81% CRC patients (73 out of 90, median number=21.5 CTCs), 7.5% CAD patients (3 out of 40), 0% patients with BCD (0 out of 90), 2.5% patients with OCC (2 out of 80) and 0% NS (0 out of 40). Furthermore, statistical analysis showed that CDX2 pCTC numbers were associated with tumour- node-metastasis stage and lymph node status. Using the median CDX2 pCTC numbers as the cutoff points, stratified groups of CRC patients had significant differences in their recurrence and survival.

Conclusions:

This study showed that the refined IE assay can detect CDX2 pCTCs with high sensitivity and that CDX2 pCTCs can generate clinically important information for CRC patients.

Aptamer based photoelectrochemical cytosensor with layer-by-layer assembly of CdSe semiconductor nanoparticles as photoelectrochemically active species

A label-free photoelectrochemical cytosensor for highly sensitive and specific detection of Ramos cell was developed based on photoactive films. The films were fabricated by a layer-by-layer (LBL) assembly of positively charged poly(dimethyldiallylammonium chloride) (PDDA) and negatively charged CdSe semiconductor nanoparticles (NPs) capped with mercaptoacetic acid. The resulting modified electrodes were tested as sensors for Ramos cell through the recognition of DNA aptamer which was covalently bound to the electrode using the classic coupling reactions between -COOH groups on the surfaces of CdSe NPs and -NH(2) groups of the aptamer. The newly developed cytosensor exhibited excellent sensitivity and selectivity. The linear range was from 160 to 1600 cells/mL and the detection limit was 84 cells/mL.

Electrochemical and electrochemiluminescence determination of cancer cells based on aptamers and magnetic beads

The electrochemical and electrochemiluminescence (ECL) detection of cell lines of Burkitt's lymphoma (Ramos) by using magnetic beads as the separation tool and high-affinity DNA aptamers for signal recognition is reported. Au nanoparticles (NPs) bifunctionalized with aptamers and CdS NPs were used for electrochemical signal amplification. The anodic stripping voltammetry technology employed for the analysis of cadmium ions dissolved from CdS NPs on the aggregates provided a means to quantify the amount of the target cells. This electrochemical method could respond down to 67 cancer cells per mL with a linear calibration range from 1.0×10(2) to 1.0×10(5) cells mL(-1), which shows very high sensitivity. In addition, the assay was able to differentiate between target and control cells based on the aptamer used in the assay, indicating the wide applicability of the assay for diseased cell detection. ECL detection was also performed by functionalizing the signal DNA, which was complementary to the aptamer of the Ramos cells, with tris(2,2-bipyridyl) ruthenium. The ECL intensity of the signal DNA, replaced by the target cells from the ECL probes, directly reflected the quantity of the amount of the cells. With the use of the developed ECL probe, a limit of detection as low as 89 Ramos cells per mL could be achieved. The proposed methods based on electrochemical and ECL should have wide applications in the diagnosis of cancers due to their high sensitivity, simplicity, and low cost.