Circulating tumour cell detection: a direct comparison between the CellSearch System, the AdnaTest and CK-19/mammaglobin RT-PCR in patients with metastatic breast cancer

Circulating tumor cells help differentiate benign ovarian lesions from cancer before surgery: A literature review and proof of concept study using flow cytometry with fluorescence imaging

Current tools are insufficient for distinguishing patients with ovarian cancer from those with benign ovarian lesions before extensive surgery. The present study utilized a readily accessible platform employing a negative selection strategy, followed by flow cytometry, to enumerate circulating tumor cells (CTCs) in patients with ovarian cancer. These counts were compared with those from patients with benign ovarian lesions. CTC counts at baseline, before and after anticancer therapy, and across various clinical scenarios involving ovarian lesions were assessed. A negative-selection protocol we proposed was applied to patients with suspected ovarian cancer and prospectively utilized in those subsequently confirmed to have malignancy. The protocol was implemented before anticancer therapy and at months 3, 6, 9 and 12 post-treatment. A cut-off value for CTC number at 4.75 cells/ml was established to distinguish ovarian malignancy from benign lesions, with an area under the curve of 0.900 (P<0.001). In patients with ovarian cancer, multivariate Cox regression analysis revealed that baseline CTC counts and the decline in CTCs within the first three months post-therapy were significant predictors of prolonged progression-free survival. Additionally, baseline CTC counts independently prognosticated overall survival. CTC counts obtained with the proposed platform, used in the present study, suggest that pre-operative CTC testing may be able to differentiate between malignant and benign tumors. Moreover, CTC counts may indicate oncologic outcomes in patients with ovarian cancer who have undergone cancer therapies.

A photoelectrochemical aptasensor based on double Z-scheme α-Fe2O3/MoS2/Bi2S3 ternary heterojunction for sensitive detection of circulating tumor cells

A novel photoelectrochemical (PEC) aptasensor based on a dual Z-scheme α-Fe2O3/MoS2/Bi2S3 ternary heterojunction for the ultrasensitive detection of circulating tumor cells (CTCs) was developed. The α-Fe2O3/MoS2/Bi2S3 nanocomposite was prepared via a step-by-step route, and the photoproduced electron/hole transfer path was speculated by conducting trapping experiments of reactive species. α-Fe2O3/MoS2/Bi2S3-modified electrodes exhibited greatly enhanced photocurrent under visible light due to the double Z-scheme charge transfer process, which met the requirement of the PEC sensor for detecting larger targets. After the aptamer was conjugated on the photoelectrode through chitosan (CS) and glutaraldehyde (GA), when MCF-7 cells were presented and captured, the photocurrent of the PEC biosensing system decreased due to steric hindrance. The current intensity had a linear relationship with the logarithm of MCF-7 cell concentration ranging from 10 to 1×105 cells mL-1, with a low detection limit of 3 cell mL-1 (S/N = 3). The dual Z-scheme α-Fe2O3/MoS2/Bi2S3 ternary heterojunction-modified PEC aptasensor exhibited high sensitivity and excellent specificity and stability. Additionally, MCF-7 cells in human serum were determined by this PEC aptasensor, exhibiting great potential as a promising tool for clinical detection.

Association between circulating tumor cells in the peripheral blood and the prognosis of gastric cancer patients: a meta-analysis

Background

Research on the correlation between circulating tumor cells (CTCs) and gastric cancer (GC) has increased rapidly in recent years. However, whether CTCs are associated with GC patient prognosis is highly controversial.

Objective

This study aims to evaluate the value of CTCs to predict the prognosis of GC patients.

Design

A meta-analysis.

Data Sources and Methods

We searched the PubMed, Embase, and Cochrane Library databases for studies that reported the prognostic value of CTCs in GC patients before October 2022. The association between CTCs and overall survival (OS) and disease-free survival (DFS)/recurrence-free survival (RFS) and progression-free survival (PFS) of GC patients was assessed. Subgroup analyses were stratified by sampling times (pre-treatment and post-treatment), detection targets, detection method, treatment method, tumor stage, region, and HR (Hazard Ratio) extraction methods. Sensitivity analysis was performed by removing individual studies to assess the stability of the results. Publication bias was evaluated using funnel plots, Egger's test, and Begg's test.

Results

We initially screened 2000 studies, of which 28 were available for further analysis, involving 2383 GC patients. The pooled analysis concluded that the detection of CTCs was associated with poor OS (HR = 1.933, 95% CI 1.657-2.256, p < 0.001), DFS/RFS (HR = 3.228, 95% CI 2.475-4.211, p < 0.001), and PFS (HR = 3.272, 95% CI 1.970-5.435, p < 0.001). Furthermore, the subgroup analysis stratified by tumor stage (p < 0.01), HR extraction methods (p < 0.001), detection targets (p < 0.001), detection method (p < 0.001), sampling times (p < 0.001), and treatment method (p < 0.001) all showed that CTC detection was associated with poor OS and DFS/RFS for GC patients. Furthermore, the study showed that CTCs were associated with the poor DFS/RFS of GC when CTCs were detected for patients from Asian or No-Asian regions (p < 0.05). In addition, higher CTCs predicted poorer OS for GC patients who are from Asian regions (p < 0.001), but without statistical difference for GC patients from No-Asian regions (p = 0.490).

Conclusion

CTC detection in peripheral blood was associated with poor OS, DFS/RFS, and PFS in patients with GC.

Bioplatforms in liquid biopsy: advances in the techniques for isolation, characterization and clinical applications

Tissue biopsy analysis has conventionally been the gold standard for cancer prognosis, diagnosis and prediction of responses/resistances to treatments. The existing biopsy procedures used in clinical practice are, however, invasive, painful and often associated with pitfalls like poor recovery of tumor cells and infeasibility for repetition in single patients. To circumvent these limitations, alternative non-invasive, rapid and economical, yet sturdy, consistent and dependable, biopsy techniques are required. Liquid biopsy is an emerging technology that fulfills these criteria and potentially much more in terms of subject-specific real-time monitoring of cancer progression, determination of tumor heterogeneity and treatment responses, and specific identification of the type and stages of cancers. The present review first briefly revisits the state-of-the-art technique of liquid biopsy and then proceeds to address in detail, the advances in the potential clinical applications of four major biological agencies present in liquid biopsy samples (circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), exosomes and tumor-educated platelets (TEPs)). Finally, the authors conclude with the limitations that need to be addressed in order for liquid biopsy to effectively replace the conventional invasive biopsy methods in the clinical settings.

Comparison of microfluidic platforms for the enrichment of circulating tumor cells in breast cancer patients

Purpose

Circulating tumor cells (CTCs) hold promise to be a non-invasive measurable biomarker in all cancer stages. Because the analysis of CTCs is still a technical challenge, we compared different types of microfluidic enrichment protocols to isolate these rare cells from the blood.

Methods

Blood samples from patients with early and metastatic breast cancer (BC) were processed using the microfluidic Parsortix® technology employing (i) a single-step cell separation using the standard GEN3D6.5 microfluidic cassette, (ii) a two-step separation with an upfront pre-enrichment, and (iii) a two-step separation with a different type of cassette. In the enriched cells, the gene expression levels of CTC-related transcripts were assessed using quantitative real-time PCR (qPCR) by Taqman® and Lightcycler (LC) technology.

Results

23/60 (38.3%) BC samples were assigned as positive due to the presence of at least one gene marker beyond the threshold level. The prevalence of epithelial markers was significantly higher in metastatic compared to early BC (EpCAM: 31.3% vs. 7.3%; CK19: 21.1% vs. 2.4%). A high level of concordance was observed between CK19 assessed by Taqman® and LC technology, and for detection of the BC-specific gene SCGB2A2. An upfront pre-enrichment resulted in lower leukocyte contamination, at the cost of fewer tumor cells captured.

Conclusion

The Parsortix® system offers both reasonable recovery of tumor cells and depletion of contaminating leukocytes when the single-step separation using the GEN3D6.5 cassette is employed. Careful selection of suitable markers and cut-off thresholds is an essential point for the subsequent molecular analysis of the enriched cells.

Detection of circulating tumor cells: opportunities and challenges

Circulating tumor cells (CTCs) are cells that shed from a primary tumor and travel through the bloodstream. Studying the functional and molecular characteristics of CTCs may provide in-depth knowledge regarding highly lethal tumor diseases. Researchers are working to design devices and develop analytical methods that can capture and detect CTCs in whole blood from cancer patients with improved sensitivity and specificity. Techniques using whole blood samples utilize physical prosperity, immunoaffinity or a combination of the above methods and positive and negative enrichment during separation. Further analysis of CTCs is helpful in cancer monitoring, efficacy evaluation and designing of targeted cancer treatment methods. Although many advances have been achieved in the detection and molecular characterization of CTCs, several challenges still exist that limit the current use of this burgeoning diagnostic approach. In this review, a brief summary of the biological characterization of CTCs is presented. We focus on the current existing CTC detection methods and the potential clinical implications and challenges of CTCs. We also put forward our own views regarding the future development direction of CTCs.

Circulating tumor cell detection: A prospective comparison between CellSearch® and RareCyte® platforms in patients with progressive metastatic breast cancer

PURPOSE

Circulating tumor cells (CTCs) are prognostic in patients with breast cancer. Several technical platforms exist for their enumeration and characterization. Comparative studies between these platforms are scarce. The RareCyte CTC detection is theoretically more sensitive than the established CellSearch platform, which identifies only CTCs that express EpCAM and cytokeratin. This study prospectively compares CTC enumeration in patients with breast cancer in a paired analysis using these two platforms. It investigates survival outcomes in groups defined by a CTC count threshold.

DESIGN

CTC enumeration was performed on 100 samples obtained from 86 patients with progressive metastatic breast cancer (MBC) in two independent laboratories each blinded to the clinical data and the results from the other platform.

RESULTS

One hundred paired samples were collected and CTC counts were determined using the CellSearch and RareCyte CTC platforms. In total, 65% and 75% of samples had at least one detectable CTC in 7.5 mL blood with the CellSearch and the RareCyte systems, respectively. CTC counts with the CellSearch system ranged from 0 to 2289 with a median of 3 CTCs, the RareCyte CTC counts ranged from 0 to 1676 with a median of 3 CTCs. The number of samples with 5 or more CTCs in 7.5 mL of blood (the poor prognosis cut-off validated with the CellSearch system) blood was 45% with the CellSearch test and 48% with the RareCyte test. CTC counts quantified with the CellSearch and the RareCyte systems were strongly correlated (Spearman's r = 0.8235 (0.7450-0.8795) p < 0.001). 86 patients were included for Kaplan-Meier survival analysis. An increased mortality risk in patients with CellSearch of 5 CTCs or more per 7.5 mL blood, with a log-rank hazard ratio of 5.164 (2.579-10.34) (p < 0.001) was confirmed. The survival analysis with RareCyte CTC counts with the identical cut-off showed a significantly impaired survival with a hazard ratio of 4.213 (2.153-8.244) (p < 0.001).

CONCLUSION

Our data demonstrate the analytical and prognostic equivalence of CellSearch and RareCyte CTC enumeration platforms in patients with MBC using the CellSearch cut-off. This is the first demonstration of prognostic significance using the RareCyte platform.

Coagulation/fibrinolysis and circulating tumor cells in patients with advanced breast cancer

Purpose

To evaluate the relationship between circulating tumor cells (CTCs) and standard coagulation tests in both a discovery and a validation cohort of patients with advanced breast cancer.

Methods

In a retrospective (n = 77) and a prospective (n = 92) study of patients with progressive advanced breast cancer, CTC count, platelet number, fibrinogen level, D-dimers, prothrombin time, and activated partial thromboplastin time were measured. The association between these coagulation studies and CTC count was analyzed. The impact of these measurements on overall survival (OS) was assessed.

Results

In both cohorts, results were similar; absolute CTC count was significantly associated to D-dimer level and inversely with platelet count. In the prospective cohort, quantification of tumor-derived extracellular vesicles (tdEVs) was associated with CTC count, and with coagulation abnormalities (low platelet count and increased D-dimers). tdEVs did not add to CTC count in predicting changes in platelets or D-dimers. In multivariate analysis only CTC ≥ 5 CTC/7.5 mL, ER status, HER2 status and lines of chemotherapy were associated with OS. In patients with terminally metastatic breast cancer, very high CTC counts are prevalent.

Conclusion

A significant association exists between increasing CTC number and increased D-dimers and decreased platelet counts, suggesting a potential role for CTCs as a direct contributor of intravascular coagulation activation. In patients with advanced and progressive breast cancer, abnormalities in routine coagulation tests is the rule. In patients with terminally advanced breast cancer a “leukemic” phase with high CTC count is prevalent.

Detection of circulating tumour cells in colorectal cancer: Emerging techniques and clinical implications

Despite several advances in oncological management of colorectal cancer, morbidity and mortality are still high and devastating. The diagnostic evaluation by endoscopy is cumbersome, which is uncomfortable to many. Because of the intra- and inter-tumour heterogeneity and changing tumour dynamics, which is continuous in nature, the diagnostic biopsy and assessment of the pathological sample are difficult and also not adequate. Late manifestation of the disease and delayed diagnosis may lead to relapse or metastases. One of the keys to improving the outcome is early detection of cancer, ease of technology to detect with uniformity, and its therapeutic implications, which are yet to come. "Liquid biopsy" is currently the most recent area of interest in oncology, which may provide important tools regarding the characterization of the primary tumour and its metastasis as cancer cells shed into the bloodstream even at the early stages of the disease. By using this approach, clinicians may be able to find out information about the tumour at a given time. Any of the following three types of sampling of biological material can be used in the "liquid biopsy". These are circulating tumour cells (CTCs), circulating tumour DNA, and exosomes. The most commonly studied amongst the three is CTCs. CTCs with their different applications and prognostic value has been found useful in colorectal cancer detection and therapeutics. In this review, we will discuss various markers for CTCs, the core tools/techniques for detection, and also important findings of clinical studies in colorectal cancer and its clinical implications.

Circulating Tumor Cells: Technologies and Their Clinical Potential in Cancer Metastasis

Circulating tumor cells (CTCs) are single cells or clusters of cells within the circulatory system of a cancer patient. While most CTCs will perish, a small proportion will proceed to colonize the metastatic niche. The clinical importance of CTCs was reaffirmed by the 2008 FDA approval of CellSearch^®, a platform that could extract EpCAM-positive, CD45-negative cells from whole blood samples. Many further studies have demonstrated the presence of CTCs to stratify patients based on overall and progression-free survival, among other clinical indices. Given their unique role in metastasis, CTCs could also offer a glimpse into the genetic drivers of metastasis. Investigation of CTCs has already led to groundbreaking discoveries such as receptor switching between primary tumors and metastatic nodules in breast cancer, which could greatly affect disease management, as well as CTC-immune cell interactions that enhance colonization. In this review, we will highlight the growing variety of isolation techniques for investigating CTCs. Next, we will provide clinically relevant context for CTCs, discussing key clinical trials involving CTCs. Finally, we will provide insight into the future of CTC studies and some questions that CTCs are primed to answer.

Inertial-Assisted Immunomagnetic Bioplatform towards Efficient Enrichment of Circulating Tumor Cells

Serving as an effective biomarker in liquid biopsy, circulating tumor cells (CTCs) can provide an accessible source for cancer biology study. For the in-depth evaluation of CTCs in cancer analysis, their efficient enrichment is essential, owing to their low abundance in peripheral blood. In this paper, self-assembled immunomagnetic beads were developed to isolate CTCs from the ordered bundles of cells under the assistance of the spiral inertial effect. Parametric numerical simulations were performed to explore the velocity distribution in the cross section. Based on this chip, rare CTCs could be recovered under the throughput of 500 μL/min, making this device a valuable supplement in cancer analysis, diagnostics, and therapeutics.

The Long-Term Prognostic Significance of Circulating Tumor Cells in Ovarian Cancer-A Study of the OVCAD Consortium

INTRODUCTION

We previously reported the prognostic impact of circulating tumor cells (CTCs) in a multicenter study on minimal residual disease in primary ovarian cancer. With additional follow-up data, we evaluated the combined CTC approach (CTCs^combo), in particular for the patients who had survived more than five years.

MATERIAL AND METHODS

Blood samples taken at baseline and six months after adjuvant treatment (follow-up) were assessed by quantitative PCR (qPCR) measuring PPIC transcripts and immunofluorescent staining (IF). A positive result with either IF or qPCR was classified as CTC^combo-positive. Further, PPIC was assessed in the primary tumor tissue.

RESULTS

The concordance of IF and qPCR was 65% at baseline and 83% after treatment. Results showed that 50.5% of the baseline and 29.5% of the follow-up samples were CTC^combo-positive. CTCs^combo after treatment were associated with increased mortality after adjusting for FIGO stage (HR 2.574, 95% CI: 1.227-5.398, p = 0.012), a higher risk of recurrence after adjusting for peritoneal carcinosis (HR 4.068, 95% CI: 1.948-8.498, p < 0.001), and increased mortality after five survived years.

DISCUSSION

The two-sided analytical approach revealed CTC subpopulations associated with ovarian cancer progression and may illuminate a potential treatment-related shift in molecular phenotypes. That approach can identify patients who have elevated risk of recurrence and death due to ovarian cancer and who may require risk-adapted treatment strategies.

Highly Correlated Recurrence Prognosis in Patients with Metastatic Colorectal Cancer by Synergistic Consideration of Circulating Tumor Cells/Microemboli and Tumor Markers CEA/CA19-9

Circulation tumor cells (CTCs) play an important role in metastasis and highly correlate with cancer progression; thus, CTCs could be considered as a powerful diagnosis tool. Our previous studies showed that the number of CTCs could be utilized for recurrence prediction in colorectal cancer (CRC); however, the odds ratio was still lower than five. To improve prognosis in CRC patients, we analyzed CTC clusters/microemboli, CTC numbers, and carcinoembryonic antigen (CEA)/carbohydrate antigen 19-9 (CA19-9) levels using a self-assembled cell array (SACA) chip system for recurrence prediction. In CRC patients, the presence of CTC clusters/microemboli may have higher correlation in metastasis when compared to the high number of CTCs. Additionally, when both the number of CTCs and serum CEA levels are high, very high odds ratios of 24.4 and 17.1 are observed in patients at all stages and stage III of CRC, respectively. The high number of CTCs and CTC clusters/microemboli simultaneously suggests the high chance of relapse (odds ratio 8.4). Overall, the characteristic of CTC clusters/microemboli, CEA level, and CTC number have a clinical potential to enhance CRC prognosis.

A Direct Comparison between the Lateral Magnetophoretic Microseparator and AdnaTest for Isolating Prostate Circulating Tumor Cells

Circulating tumor cells (CTCs) are important biomarkers for the diagnosis, prognosis, and treatment of cancer. However, because of their extreme rarity, a more precise technique for isolating CTCs is required to gain deeper insight into the characteristics of cancer. This study compares the performance of a lateral magnetophoretic microseparator (“CTC-μChip”), as a representative microfluidic device, and AdnaTest ProstateCancer (Qiagen), as a commercially available specialized method, for isolating CTCs from the blood of patients with prostate cancer. The enumeration and genetic analysis results of CTCs isolated via the two methods were compared under identical conditions. In the CTC enumeration experiment, the number of CTCs isolated by the CTC-μChip averaged 17.67 CTCs/mL, compared to 1.56 CTCs/mL by the AdnaTest. The number of contaminating white blood cells (WBCs) and the CTC purity with the CTC-μChip averaged 772.22 WBCs/mL and 3.91%, respectively, whereas those with the AdnaTest averaged 67.34 WBCs/mL and 1.98%, respectively. Through genetic analysis, using a cancer-specific gene panel (AR (androgen receptor), AR-V7 (A\androgen receptor variant-7), PSMA (prostate specific membrane antigen), KRT19 (cytokeratin-19), CD45 (PTPRC, Protein tyrosine phosphatase, receptor type, C)) with reverse transcription droplet digital PCR, three genes (AR, AR-V7, and PSMA) were more highly expressed in cells isolated by the CTC-μChip, while KRT19 and CD45 were similarly detected using both methods. Consequently, this study showed that the CTC-μChip can be used to isolate CTCs more reliably than AdnaTest ProstateCancer, as a specialized method for gene analysis of prostate CTCs, as well as more sensitively obtain cancer-associated gene expressions.

Circulating Tumor Cells: State-of-the-art Update on Technologies and Clinical Applications

PURPOSE OF REVIEW

Circulating tumor cells represent rare events in the peripheral blood of patients with cancer that can provide insight into tumor biology. CTC enumeration, isolation, and analysis represent liquid biopsy approaches whose role in the management of patients with cancer continues to evolve in the era of precision medicine. This review presents an overview of technologies central to studying CTCs.

RECENT FINDINGS

Technologies for CTC isolation can be divided into two categories: label-dependent and label-independent. Label-dependent techniques utilize biological properties such as cell surface proteins, while label-independent techniques utilize distinctive physical properties such as cell size, density, and plasticity. Advances in microfluidics designs as well as hybrid combinations of label-dependent and label-independent techniques have resulted in unprecedented improvements in CTC isolation, permitting not only the detection and enumeration of these rare events but also providing the means for studying them and exploring them as a new dimension of cancer biomarkers. With advances in tools for isolating and studying CTCs in hand, questions regarding the clinical utility of CTC enumeration in peripheral blood, detection of CTC-associated biomarkers, and analysis of dynamic changes in CTCs during the course of cancer therapy represent exciting new opportunities for cancer research.

Enumeration and molecular characterization of circulating tumor cells as an innovative tool for companion diagnostics in breast cancer

INTRODUCTION

Circulating tumor cells (CTC) and more recently, CTC clusters are implicated as a fundamental mechanism by which tumor cells break away from the primary site and travel to distant sites. Enumeration of CTC and CTC clusters represents a new approach to prognosis, prediction, and response to therapy in patients with early and metastatic breast cancer. Several recent studies have shown the predictive importance of monitoring CTCs levels in progression-free and overall survival in breast cancer patients. This review will focus on CTC enumeration and characterization in breast cancers.

AREAS COVERED

We will provide a historical perspective and clinical background of CTC detection in peripheral blood. The current methodologies for studying CTCs and newer technologies for CTC detection will be reviewed together with the current state of the art of CTCs as a biomarker in risk stratification and prognostication in breast cancers.

EXPERT OPINION

Currently, there is an FDA approved CTC assessment method for clinical use. While CTC enumeration, is a marker for prognostication and survival, molecular characterization of CTC, may be more accurate in monitoring response to treatment due to tumor heterogeneity rather than the tumor phenotype at the primary or metastatic sites.

The Prognostic Value of Circulating Tumor Cells in Primary Breast Cancer Prior to any Systematic Therapy: A Systematic Review

BACKGROUND

Numerous studies have defined the outstanding role of circulating tumor cells (CTC) in the management of cancer, particularly the ones in association with primary tumor metastases.

OBJECTIVE

The overall aim of the present study was to investigate whether CTCs may serve as a clinical prognostic marker for survival in primary breast cancer.

METHODS

Articles Published from June 2011 to July 2017 in PubMed, EMBase, and Cochrane library databases were thoroughly screened for selecting the ones meeting the inclusion criteria.

RESULT

Studies applying CellSearch® method demonstrated the risk ratios (RR) of 2.51 (95% CI: 1.78- 3.54), 3.98 (95% CI: 2.28- 6.95), 5.59 (95% CI: 3.29- 9.51), and 3.38 (95% CI: 1.88- 6.06) for death rate and relapse rates of 2.48 (95% CI: 1.89 - 3.26), 3.62 (95% CI: 2.37 - 5.51), 4.45 (95% CI: 2.94 - 6.73), and 2.88 (95 % CI: 1.99 - 4.17) at four CTC positive cut points (≥ 1, ≥ 2, ≥ 3, and ≥ 5 CTCs/7.5 ml). Two studies applying the AdnaTest® also documented increased death (RR: 1.38, 95 % CI: 0.42- 4.49) and relapse rates (RR: 2.97, 95 % CI: 1.23 - 7.18)).

CONCLUSION

Results of this meta-analysis allude CTCs as potent prognostic markers in primary breast cancers prior to any systemic therapy especially when it is studied via CellSearch® administration, considering that the more the CTCs, the greater the death and relapse rates.

Circulating tumor cells in precision oncology: clinical applications in liquid biopsy and 3D organoid model

Circulating tumor cells (CTCs) are a rare subset of cells found in the blood of patients with solid tumors, which function as a seed for metastases. Cancer cells metastasize through the bloodstream either as single migratory CTCs or as multicellular groupings-CTC clusters. The CTCs preserve primary tumor heterogeneity and mimic tumor properties, and may be considered as clinical biomarker, preclinical model, and therapeutic target. The potential clinical application of CTCs is being a component of liquid biopsy. CTCs are also good candidates for generating preclinical models, especially 3D organoid cultures, which could be applied in drug screening, disease modeling, genome editing, tumor immunity, and organoid biobanks. In this review, we summarize current knowledge on the value and promise of evolving CTC technologies and highlight cutting-edge research on CTCs in liquid biopsy, tumor metastasis, and organoid preclinical models. The study of CTCs offers broad pathways to develop new biomarkers for tumor patient diagnosis, prognosis, and response to therapy, as well as translational models accelerating oncologic drug development.

Prognostic and therapeutic significance of circulating tumor cells in patients with lung cancer

BACKGROUND

Lung cancer is the second most common cancer and the main cause of cancer-related mortality worldwide. In spite of various efforts that have been made to facilitate the early diagnosis of lung cancer, most patients are diagnosed when the disease is already in stage IV, which is generally associated with the occurrence of distant metastases and a poor survival. Moreover, a large proportion of these patients will relapse after treatment, heralding the need for the stratification of lung cancer patients in addition to identifying those who are at a higher risk of relapse and, thus, require alternative and/or additional therapies. Recently, circulating tumor cells (CTCs) have been considered as valuable markers for the early diagnosis, prognosis and risk stratification of cancer patients, and they have been found to be able to predict the survival of patients with various types of cancer, including lung cancer. Additionally, the characterization of CTCs has recently provided fascinating insights into the heterogeneity of tumors, which may be instrumental for the development of novel targeted therapies.

CONCLUSIONS

Here we review our current understanding of the significance of CTCs in lung cancer metastasis. We also discuss prominent studies reporting the utility of enumeration and characterization of CTCs in lung cancer patients as prognostic and pharmacodynamic biomarkers for those who are at a higher risk of metastasis and drug resistance.

Pathophysiology of Tumor Cell Release into the Circulation and Characterization of CTC

The traditional model of metastatic progression postulates that the ability to form distant metastases is driven by random mutations in cells of the primary tumor.

Detection of human mammaglobin mRNA in breast cancer cells among Vietnamese women

Background

Detecting circulating tumor cells (CTCs) is a promising approach for evaluating the progression of occult metastases as well as the efficacy of treatment therapies among patients with breast cancer. A real-time reverse transcriptase polymerase chain reaction (RT-PCR) technique has been proposed for detecting CTCs due to its high sensitivity. In this study, we aimed to validate the RT-PCR technique for human mammaglobin (hMAM) mRNA detection among Vietnamese women with breast cancer.

Patients and methods

Peripheral blood samples and breast cancer tissues from 43 patients suffering from breast cancer and 21 patients with fibroids were obtained. Real-time RT-PCR and gene sequencing techniques were employed to detect hMAM gene in CTCs of breast cancer cell lines and cancer tissues.

Results

hMAM mRNA transcription was detected in 36 out of 43 (83.7%) breast cancer tissues and in blood of 23 out of 43 (53.5%) breast cancer patients, while it was detected in only 9.5% out of tissues and 0% of the blood of fibrosis patients. hMAM mRNA in the peripheral blood of breast cancer patients increased with tumor size, stage of cancer and distant metastasis (P<0.05). No difference in the expression of hMAM mRNA was found in breast cancer tissue regarding age, distant metastasis, lymph node, stages of cancer and histopathology (P>0.05).

Conclusion

The study highlighted the expression of hMAM mRNA in breast cancer cells and tissues. This reveals the overall picture of the replication of hMAM mRNA in breast cancer, suggesting the role of hMAM mRNA in breast cancer molecular pathology.

CTCs as a prognostic and predictive biomarker for stage II/III Colon Cancer: a companion study to the PePiTA trial

BACKGROUND

Adjuvant therapy improves the prognosis of stage II & III colon cancer patients. Unfortunately, most patients do not benefit from this treatment. PePITA (NCT00994864) is a prospective, multicenter, non-randomized study whose primary objective is to predict the outcome of adjuvant therapy in colon cancer.

METHODS

The primary objective was to determine the prognostic and predictive value of circulating tumor cell (CTC) detection before therapy and after one course of preoperative FOLFOX.

RESULTS

Out of the 58 first patients accrued in PePiTA trial, 36 patients participated in the CTC companion study, of whom 32 had at least one evaluable sample. Only 5 patients (14, 95% CI = 5-30%) had ≥1 CTC/22.5 ml blood in at least one of the two timepoints with 2 patients having ≥1 CTC/22.5 ml at baseline (6, 95% CI: 1-19%). The detection rate of patients with CTCs at baseline being lower than expected, the inclusion of patients in the PePiTA CTC substudy was stopped. The limited sample size did not allow us to investigate the prognostic and predictive value of CTCs in locally advanced colon cancer.

CONCLUSIONS

Our data illustrate the need for further standardized studies in order to find the most reliable prognostic/predictive biomarker in early-stage colon cancer.

TRIAL REGISTRATION

This trial was prospectively registered at Jules Bordet institute ( NCT00994864 ) on the October 14, 2009.

Non-Metastatic Esophageal Adenocarcinoma: Circulating Tumor Cells in the Course of Multimodal Tumor Treatment

BACKGROUND

Isolation of circulating tumor cells (CTC) holds the promise to improve response-prediction and personalization of cancer treatment. In this study, we test a filtration device for CTC isolation in patients with non-metastatic esophageal adenocarcinoma (EAC) within recent multimodal treatment protocols.

METHODS

Peripheral blood specimens were drawn from EAC patients before and after neoadjuvant chemotherapy (FLOT)/chemoradiation (CROSS) as well as after surgery. Filtration using ScreenCell^® devices captured CTC for cytologic analysis. Giemsa-stained specimens were evaluated by a cytopathologist; the cut-off was 1 CTC/specimen (6 mL). Immunohistochemistry with epithelial (pan-CK) and mesenchymal markers (vimentin) was performed.

RESULTS

Morphologically diverse malignant CTCs were found in 12/20 patients in at least one blood specimen. CTCs were positive for both vimentin and pan-CK. More patients were CTC positive after neoadjuvant therapy (6/20 vs. 9/15) and CTCs per/ml increased in most of the CTC-positive patients. After surgery, 8/13 patients with available blood specimens were still CTC positive. In clinical follow-up, 5/9 patients who died were CTC-positive.

CONCLUSIONS

Detection of CTC by filtration within multimodal treatment protocols of non-metastatic EAC is feasible. The rate of CTC positive findings and the quantity of CTCs changes in the course of multimodal neoadjuvant chemoradiation/chemotherapy and surgery.

Spectrum of Epithelial-Mesenchymal Transition Phenotypes in Circulating Tumour Cells from Early Breast Cancer Patients

Circulating tumour cells (CTCs) can provide valuable prognostic information in a number of epithelial cancers. However, their detection is hampered due to their molecular heterogeneity, which can be induced by the epithelial-mesenchymal transition (EMT) process. Therefore, current knowledge about CTCs from clinical samples is often limited due to an inability to isolate wide spectrum of CTCs phenotypes. In the current work, we aimed at isolation and molecular characterization of CTCs with different EMT status in order to establish their clinical significance in early breast cancer patients. We have obtained CTCs-enriched blood fraction from 83 breast cancer patients in which we have tested the expression of epithelial, mesenchymal and general breast cancer CTCs markers (MGB1/HER2/CK19/CDH1/CDH2/VIM/PLS3), cancer stem cell markers (CD44, NANOG, ALDH1, OCT-4, CD133) and cluster formation gene (plakoglobin). We have shown that in the CTCs-positive patients, epithelial, epithelial-mesenchymal and mesenchymal CTCs markers were detected at a similar rate (in 28%, 24% and 24%, respectively). Mesenchymal CTCs were characterized by the most aggressive phenotype (significantly higher expression of CXCR4, uPAR, CD44, NANOG, p < 0.05 for all), presence of lymph node metastases (p = 0.043), larger tumour size (p = 0.023) and 7.33 higher risk of death in the multivariate analysis (95% CI 1.06–50.41, p = 0.04). Epithelial-mesenchymal subtype, believed to correspond to highly plastic and aggressive state, did not show significant impact on survival. Gene expression profile of samples with epithelial-mesenchymal CTCs group resembled pure epithelial or pure mesenchymal phenotypes, possibly underlining degree of EMT activation in particular patient’s sample. Molecular profiling of CTCs EMT phenotype provides more detailed and clinically informative results, proving the role of EMT in malignant cancer progression in early breast cancer.

Entrapment of Prostate Cancer Circulating Tumor Cells with a Sequential Size-Based Microfluidic Chip

Circulating tumor cells (CTCs) are broadly accepted as an indicator for early cancer diagnosis and disease severity. However, there is currently no reliable method available to capture and enumerate all CTCs as most systems require either an initial CTC isolation or antibody-based capture for CTC enumeration. Many size-based CTC detection and isolation microfluidic platforms have been presented in the past few years. Here we describe a new size-based, multiple-row cancer cell entrapment device that captured LNCaP-C4-2 prostate cancer cells with >95% efficiency when in spiked mouse whole blood at ∼50 cells/mL. The capture ratio and capture limit on each row was optimized and it was determined that trapping chambers with five or six rows of micro constriction channels were needed to attain a capture ratio >95%. The device was operated under a constant pressure mode at the inlet for blood samples which created a uniform pressure differential across all the microchannels in this array. When the cancer cells deformed in the constriction channel, the blood flow temporarily slowed down. Once inside the trapping chamber, the cancer cells recovered their original shape after the deformation created by their passage through the constriction channel. The CTCs reached the cavity region of the trapping chamber, such that the blood flow in the constriction channel resumed. On the basis of this principle, the CTCs will be captured by this high-throughput entrapment chip (CTC-HTECH), thus confirming the potential for our CTC-HTECH to be used for early stage CTC enrichment and entrapment for clinical diagnosis using liquid biopsies.

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.

CK19, CK20, EGFR and HER2 Status of Circulating Tumor Cells in Patients with Breast Cancer

Aims and background

The major cause of death in breast cancer patients is metastasis. Various biomarkers have been used for the early detection of circulating tumor cells in the peripheral blood of breast cancer patients. The aims of the current study were to analyze circulating tumor cells in the blood of breast cancer patients by investigating EGFR, CK19, CK20 and HER2 expression profiles and to evaluate their prognostic importance.

Methods

CK19, CK20 and EGFR gene expression profiles were evaluated in the blood samples of 84 female patients with primary invasive ductal breast cancer and 20 healthy female volunteers using SYBR green-based real-time qPCR assays. HER2 expression analyses were conducted in 46 patients who had an HER2-positive primary tumor and in 30 healthy women to determine the cutoff level of positivity.

Results

The positive rates of CK20, EGFR, CK19 and HER2 mRNA expression in the peripheral blood were 28.57% (24/84), 20.23% (17/84), 5.95% (5/84) and 2.17% (1/46), respectively. The high positive ratio of CK20 mRNA expression in the peripheral blood of breast cancer was identified for the first time in the current study. Significant differences were identified in CK20 expression status and several clinical parameters related with aggressiveness of tumors using a binary logistic regression analysis. Higher CK20-positive levels were observed in patients who had lymph node metastasis and advanced-grade primary tumors, which were estrogen receptor-negative. We have demonstrated that CK20 may be a novel biomarker that is useful to identify circulating tumor cells and predict breast cancer progression.

Conclusions

The results suggest that the investigation of CK20 mRNA with other biomarkers in the peripheral blood of breast cancer patients may be useful to monitor the presence of disseminated tumor cells in the blood circulation and to predict the prognosis of breast cancer.

Advancements in microfluidic technologies for isolation and early detection of circulating cancer-related biomarkers

Isolation of circulating biomarkers using microfluidic devices for cancer diagnosis.

Molecularly imprinted nanoparticles for inhibiting ribonuclease in reverse transcriptase polymerase chain reaction

We showed that molecularly imprinted nanoparticles (nanoMIPs) could efficiently inhibit the activities of the RNase in RT-PCR reactions, demonstrating that the tailor-made nanomaterials are very promising for use in routine biological assays.

Molecular Profiling and Significance of Circulating Tumor Cell Based Genetic Signatures

Cancer kills by metastasizing beyond the primary site. Early detection, surgical intervention and other treatments have improved the survival rates of patients with cancer, however, once metastasis occurs, responses to conventional therapies become significantly less effective, and this remains the leading cause of death. Circulating tumor cells (CTCs) are tumor cells that have preferentially disseminated from the primary tumor mass into the hematological system, and are en route to favorable distant sites where if they survive, can develop into metastases. They may be the earliest detectable cells with metastatic ability, and are gaining increasing attention because of their prognostic value in many types of cancers including breast, prostate, colon and lung. Recent technological advances have removed barriers that previously hindered the detection and isolation of these rare cells from blood, and have exponentially improved the genetic resolution at which we can characterize signatures that define CTCs. Some of the most significant observations from such examinations are described here. Firstly, aberrations that were thought to be unique to CTCs are detected at subclonal frequencies within primary tumors with measurable heterogeneity, indicating pre-existing genetic signatures for metastasis. Secondly, these subclonal events are enriched in CTCs and metastases, pointing towards the selection of a more 'fit' component of tumor cells with survival advantages. Lastly, this component of cancer cells may also be the chemoresistant portion that escapes systemic treatment, or acquires resistance during progression of the disease. The future of cancer management may include a standardized method of measuring intratumor heterogeneity of the primary as well as matched CTCs. This will help identify and target rare aberrations within primary tumors that make them more adept to disseminate, and also to monitor the development of treatment resistant subclones as cancer progresses.

Gene Expression Signatures in Circulating Tumor Cells Correlate with Response to Therapy in Metastatic Breast Cancer

BACKGROUND

Circulating tumor cells (CTCs) are thought to be an ideal surrogate marker to monitor disease progression in metastatic breast cancer (MBC). We investigated the prediction of treatment response in CTCs of MBC patients on the basis of the expression of 46 genes.

METHODS

From 45 MBC patients and 20 healthy donors (HD), 2 × 5 mL of blood was collected at the time of disease progression (TP0) and at 2 consecutive clinical staging time points (TP1 and TP2) to proceed with the AdnaTest EMT-2/StemCellSelectTM (QIAGEN). Patients were grouped into (a) responder (R) and non-responder (NR) at TP1 and (b) overall responder (OR) and overall non-responder (ONR) at TP2. A 46-gene PCR assay was used for preamplification and high-throughput gene expression profiling. Data were analyzed by use of GenEx (MultiD) and SAS.

RESULTS

The CTC positivity was defined by the four-gene signature (EPCAM, KRT19, MUC1, ERBB2 positivity). Fourteen genes were identified as significantly differentially expressed between CTC+ and CTC− patients (KRT19, FLT1, EGFR, EPCAM, GZMM, PGR, CD24, KIT, PLAU, ALDH1A1, CTSD, MKI67, TWIST1, and ERBB2). KRT19 was highly expressed in CTC+ patients and ADAM17 in the NR at TP1. A significant differential expression of 4 genes (KRT19, EPCAM, CDH1, and SCGB2A2) was observed between OR and ONR when stratifying the samples into CTC+ or CTC−.

CONCLUSIONS

ADAM17 could be a key marker in distinguishing R from NR, and KRT19 was powerful in identifying CTCs.

Phase Ib Pilot Study to Evaluate Reparixin in Combination with Weekly Paclitaxel in Patients with HER-2-Negative Metastatic Breast Cancer

Purpose: Chemokine receptor 1 (CXCR1) is recognized as an actionable receptor selectively expressed by breast cancer stem cells (BCSCs). Reparixin is an investigational allosteric inhibitor of chemokine receptors 1 and 2 (CXCR1/2), and demonstrates activity against BCSCs in human breast cancer xenografts. This phase Ib clinical trial examined dose, safety, and pharmacokinetics of paclitaxel plus reparixin therapy, and explored effects of reparixin on BCSCs in patients with metastatic breast cancer (MBC) (trial registration ID: NCT02001974).Experimental Design: Eligible patients had MBC and were candidates for paclitaxel therapy. Study treatment included a 3-day run-in with reparixin oral tablets three times a day, followed by paclitaxel 80 mg/m2/week (days 1, 8, and 15 for 28-day cycle) + reparixin tablets three times a day for 21/28 days; three dose cohorts were examined in a 3+3 dose escalation schema. Additional patients were recruited into an expansion cohort at the recommended phase II dose to further explore pharmacokinetics, safety, and biological effects of the combination therapy.Results: There were neither G4-5 adverse events nor serious adverse events related to study therapy and no interactions between reparixin and paclitaxel to influence their respective pharmacokinetic profiles. A 30% response rate was recorded, with durable responses >12 months in two patients. Exploratory biomarker analysis was inconclusive for therapy effect on BCSCs.Conclusions: Weekly paclitaxel plus reparixin in MBC appeared to be safe and tolerable, with demonstrated responses in the enrolled population. Dose level 3, 1200 mg orally three times a day, was selected for further study in a randomized phase II trial (NCT02370238). Clin Cancer Res; 23(18); 5358-65. ©2017 AACR.

Nanomaterial-based Microfluidic Chips for the Capture and Detection of Circulating Tumor Cells

Circulating tumor cells (CTCs), a type of cancer cells that spreads from primary or metastatic tumors into the bloodstream, can lead to a new fatal metastasis. As a new type of liquid biopsy, CTCs have become a hot pursuit and detection of CTCs offers the possibility for early diagnosis of cancers, earlier evaluation of chemotherapeutic efficacy and cancer recurrence, and choice of individual sensitive anti-cancer drugs. The fundamental challenges of capturing and characterizing CTCs are the extremely low number of CTCs in the blood and the intrinsic heterogeneity of CTCs. A series of microfluidic devices have been proposed for the analysis of CTCs with automation capability, precise flow behaviors, and significant advantages over the conventional larger scale systems. This review aims to provide in-depth insights into CTCs analysis, including various nanomaterial-based microfluidic chips for the capture and detection of CTCs based on the specific biochemical and physical properties of CTCs. The current developmental trends and promising research directions in the establishment of microfluidic chips for the capture and detection of CTCs are also discussed.

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.

Circulating tumor cells and serum levels of MMP-2, MMP-9 and VEGF as markers of the metastatic process in patients with high risk of metastatic progression

BACKGROUND AND AIMS

Metastases are a severe complication in cancer patients and biomarkers predicting their progression are still lacking for specific groups of patients. HER2 positive breast cancer (HER2 BC) patients on trastuzumab therapy are at risk of the development of unpredictable and often fatal central nervous system (CNS) metastases and castration resistant prostate cancer (CRPC) patients urgently need a marker of disease progression during therapy. Proposed metastatic markers: circulating tumor cells (CTC), serum levels of matrix metalloproteinase 2 (MMP-2), 9 (MMP-9) and vascular endothelial growth factor (VEGF) were prospectively studied to confirm their utility in these two narrowly defined groups of cancer patients.

PATIENTS AND METHODS

The groups comprised 44 advanced HER2 BC, 24 CRPC patients and 42 healthy controls. An immunomagnetic separation method followed by PCR and electrophoretic detection (AdnaGen, Germany) were used for CTC determination. Serum marker levels were determined by the ELISAs (R&D System, USA).

RESULTS

MMP-2 serum level was significantly higher in HER2 BC patients who developed CNS metastases, especially if there were also bone metastases. CTCs were a negative predictive marker for overall survival in HER2 BC patients. MMP-9 serum level was significantly higher in CRPC patients in whom disease progression occurred. CTC vanished from the blood of most of the CRPC patients (from 88% to 37%) during chemotherapy.

CONCLUSION

MMP-2 serum level and CTCs show the potential to predict CNS metastases and overall survival in BC patients. CTCs and MMP-9 serum level could be a promising therapy response marker in CRPC patients.

Comparison of three different methods for the detection of circulating tumor cells in mice with lung metastasis

Circulating tumor cells (CTCs) represent the key step of cancer cell dissemination. The alteration of CTCs correlates with the treatment outcome and prognosis. To enrich and identify CTCs from billions of blood cells renders a very challenging task, which triggers development of several methods, including lysis of RBC plus negative or positive enrichment using antibodies, and filter membrane or spiral microfluidics to capture CTCs. To compare the advantages of different enrichment methods for CTCs, we utilized the 4T1 breast cancer cells transfected with both green fluorescent protein (GFP) and luciferase to trace CTCs in the experimental lung metastasis model. Three methods were used to detect CTCs at the same time: bioluminescence assay, smearing method, and membrane filter method. The in vivo alive mouse imaging was used to dynamically monitor the growth of lung metastases. The sensitivity and accuracy of three detection methods were compared side-by-side. Our results showed that 1) the sensitivity of bioluminescence assay was the highest, but there was no information of CTC morphology; 2) the smearing method and membrane filter method could observe the detail of CTC morphology, such as in single or in cluster, while their sensitivity was lower than bioluminescence assay; 3) A dynamic observation at a 7-day intervals, the lung metastatic cancer grew at a log speed, while CTCs were increased at a low speed. This might be due to the activated immune cells eliminating the CTCs at a speed much faster than CTCs were generated. This comparison of three CTC detection methods in mouse model suggests that bioluminescence assay could be used in quantitative study of the effect of certain agent on the suppression of CTCs, while GFP-based morphological assays could be used to study the dissemination mechanism of CTCs. The combination of both bioluminescence assay and GFP-based assay would generate more information for quantity and quality of CTCs.

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.

In situ single cell detection via microfluidic magnetic bead assay

We present a single cell detection device based on magnetic bead assay and micro Coulter counters. This device consists of two successive micro Coulter counters, coupled with a high gradient magnetic field generated by an external magnet. The device can identify single cells in terms of the transit time difference of the cell through the two micro Coulter counters. Target cells are conjugated with magnetic beads via specific antibody and antigen binding. A target cell traveling through the two Coulter counters interacts with the magnetic field, and have a longer transit time at the 1st counter than that at the 2nd counter. In comparison, a non-target cell has no interaction with the magnetic field, and hence has nearly the same transit times through the two counters. Each cell passing through the two counters generates two consecutive voltage pulses one after the other; the pulse widths and magnitudes indicating the cell’s transit times through the counters and the cell’s size respectively. Thus, by measuring the pulse widths (transit times) of each cell through the two counters, each single target cell can be differentiated from non-target cells even if they have similar sizes. We experimentally proved that the target human umbilical vein endothelial cells (HUVECs) and non-target rat adipose-derived stem cells (rASCs) have significant different transit time distribution, from which we can determine the recognition regions for both cell groups quantitatively. We further demonstrated that within a mixed cell population of rASCs and HUVECs, HUVECs can be detected in situ and the measured HUVECs ratios agree well with the pre-set ratios. With the simple device structure and easy sample preparation, this method is expected to enable single cell detection in a continuous flow and can be applied to facilitate general cell detection applications such as stem cell identification and enumeration.

Clinical significance of circulating tumor cells in patients with small-cell lung cancer

BACKGROUND

This study investigated the correlation of the presence of circulating tumor cells (CTCs) with clinical characteristics, and the predictive value of CTCs for progression-free survival (PFS) in patients with small-cell lung cancer (SCLC).

METHODS

Samples were obtained from 42 patients with SCLC before and after the first cycle of chemotherapy. CTCs were quantitated by negative immunomagnetic enrichment and immunocytochemistry using anti-CD45 and anti-pancytokeratin antibodies.

RESULTS

CTCs were positive (≥2) in 76.19% of patients with SCLC and negative in the control group. The presence of CTCs was positively correlated with 6 clinical characteristics. PFS was 6.055 and 10.670 months for patients with ≥2 and <2 CTCs/7.5 mL of blood before chemotherapy; after chemotherapy PFS was 4.862 and 10.535 months, respectively.

CONCLUSIONS

This study showed that both baseline CTC numbers and the change in CTC numbers after 1 cycle of chemotherapy are significant prognostic factors of PFS for SCLC.

Detection of Circulating Tumor Cells in Breast Cancer Patients Using Cytokeratin-19 Real-Time RT-PCR

PURPOSE

The roles of circulating tumor cells (CTCs) as predictive and prognostic factors, as well as key mediators in the metastatic cascade, have been investigated. This study aimed to validate a method to quantify CTCs in peripheral blood using a real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay for cytokeratin (CK)-19 and to evaluate the utility of this assay in detecting CTCs in breast cancer patients.

MATERIALS AND METHODS

Real-time monitoring PCR of fluorescently labeled specific hybridization probes for CK-19 mRNA was established. Peripheral blood samples from 30 healthy donors, 69 patients with early breast cancer, 47 patients with locally advanced breast cancer, and 126 patients with metastatic breast cancer were prospectively obtained and analyzed for CTC detection.

RESULTS

CK-19 mRNA was not detectable in healthy subjects using the real-time RT-PCR method. The detection rates of CK-19 mRNA in breast cancer patients were 47.8% for early breast cancer (33/69), 46.8% for locally advanced breast cancer (22/47), and 61.1% for metastatic breast cancer (77/129). The detection rate of CK-19-positive CTCs in metastatic disease was slightly higher than early or locally advanced breast cancer; however, the detection rate according to disease burden was not statistically different (p=0.097). The detection rate was higher in patients with pleural metastasis (p=0.045). CTC detection was associated with poor survival (p=0.014).

CONCLUSION

A highly specific and sensitive CK-19 mRNA-based method to detect CTCs in peripheral blood in breast cancer patients can be used in further prospective studies to evaluate the predictive and prognostic importance of CTCs.

Simple and rapid colorimetric detection of melanoma circulating tumor cells using bifunctional magnetic nanoparticles

The rapid and sensitive detection of melanoma circulating tumor cells was achieved utilizing the nanozyme activity and separation property of magnetic nanoparticles.

Gold Nanoparticle Based Platforms for Circulating Cancer Marker Detection

Detection of cancer-related circulating biomarkers in body fluids has become a cutting-edge technology that has the potential to noninvasively screen cancer, diagnose cancer at early stage, monitor tumor progression, and evaluate therapy responses. Traditional molecular and cellular detection methods are either insensitive for early cancer intervention or technically costly and complicated making them impractical for typical clinical settings. Due to their exceptional structural and functional properties that are not available from bulk materials or discrete molecules, nanotechnology is opening new horizons for low cost, rapid, highly sensitive, and highly specific detection of circulating cancer markers. Gold nanoparticles have emerged as a unique nanoplatform for circulating biomarker detection owning to their advantages of easy synthesis, facile surface chemistry, excellent biocompatibility, and remarkable structure and environment sensitive optical properties. In this review, we introduce current gold nanoparticle-based technology platforms for the detection of four major classes of circulating cancer markers - circulating tumor cells, vesicles, nucleic acids, and proteins. The techniques will be summarized in terms of signal detection strategies. Distinctive examples are provided to highlight the state-of-the-art technologies that significantly advance basic and clinical cancer research.

Detection and Clinical Significance of Circulating Tumor Cells in Patients Undergoing Radical Cystectomy for Urothelial Bladder Cancer

INTRODUCTION

Estimation of prognosis is patients undergoing radical cystectomy is often unreliable, as occult disease remains undetected by conventional diagnostic tools. The purpose of this study was to evaluate the feasibility and the clinical significance of a polymerase chain reaction assay to detect cytokeratin 7 (CK7) mRNA expression in peripheral blood cells of patients undergoing radical cystectomy for clinically nonmetastatic bladder cancer.

PATIENTS AND METHODS

From 2005 to 2009, 59 patients undergoing radical cystectomy and pelvic lymph node dissection were prospectively investigated. Peripheral blood was collected prior to surgery, and a nested polymerase chain reaction assay was developed to identify patients with circulating cells expressing CK7 mRNA. Preoperative, histopathologic data and clinical outcome were compared with CK7 findings.

RESULTS

CK7 expression was detected in 23 (38.9%) of 59 patients and correlated to T stage and lymph node status. After a median follow-up of 42 months, 29 patients experienced a recurrence, whereas 36 died. The presence of CK7-positive cells was significantly associated with an increased risk for recurrence and decreased survival as compared with patients who were CK7-negative (P < .001 and P < .001, respectively; hazard ratios of 8.77 and 5.2 for recurrence and overall death, respectively). The detection of CK7-positive cells was an independent predictor of recurrence and death in a multivariable analysis.

CONCLUSION

The detection of CK7 mRNA in the circulating cells of patients undergoing radical cystectomy for urothelial cancer identifies those with significantly increased risk of cancer recurrence and death.

From Normal Skin to Squamous Cell Carcinoma: A Quest for Novel Biomarkers

Squamous cells carcinoma (SCC) is the second most frequent of the keratinocyte-derived malignancies after basal cell carcinoma and is associated with a significant psychosocial and economic burden for both the patient himself and society. Reported risk factors for the malignant transformation of keratinocytes and development of SCC include ultraviolet light exposure, followed by chronic scarring and inflammation, exposure to chemical compounds (arsenic, insecticides, and pesticides), and immune-suppression. Despite various available treatment methods and recent advances in noninvasive or minimal invasive diagnostic techniques, the risk recurrence and metastasis are far from being negligible, even in patients with negative histological margins and lymph nodes. Analyzing normal, dysplastic, and malignant keratinocyte proteome holds special promise for novel biomarker discovery in SCC that could be used in the future for early detection, risk assessment, tumor monitoring, and development of targeted therapeutic strategies.

Circulating Tumor Cells

Circulating Tumor Cells (CTC) are shed from primary or secondary tumors. Prior studies have demonstrated that enumeration of CTC is a robust independent prognostic factor of progression free and overall survival in patients with early and metastatic breast cancer. CTC, as well as other circulating tumor markers, have the appealing advantages over tissue biopsy of (1) ease of collection, (2) serial evaluation, and (3) interrogation of the entire tumor burden instead of just a limited part of the tumor. Advances have been recently made in phenotyping and genotyping of CTC, which should provide insights into the predictive role of CTC for sensitivity or resistance to therapies. In addition, CTC phenotypic marker changes during the course of treatment may serve as pharmacodynamic monitoring tools. Therefore, CTC may be considered "liquid biopsies," providing prognostic and predictive clinical information as well as additional understanding of tumor heterogeneity.

Nanoroughened adhesion-based capture of circulating tumor cells with heterogeneous expression and metastatic characteristics

BACKGROUND

Circulating tumor cells (CTCs) have shown prognostic relevance in many cancer types. However, the majority of current CTC capture methods rely on positive selection techniques that require a priori knowledge about the surface protein expression of disseminated CTCs, which are known to be a dynamic population.

METHODS

We developed a microfluidic CTC capture chip that incorporated a nanoroughened glass substrate for capturing CTCs from blood samples. Our CTC capture chip utilized the differential adhesion preference of cancer cells to nanoroughened etched glass surfaces as compared to normal blood cells and thus did not depend on the physical size or surface protein expression of CTCs.

RESULTS

The microfluidic CTC capture chip was able to achieve a superior capture yield for both epithelial cell adhesion molecule positive (EpCAM+) and EpCAM- cancer cells in blood samples. Additionally, the microfluidic CTC chip captured CTCs undergoing transforming growth factor beta-induced epithelial-to-mesenchymal transition (TGF-β-induced EMT) with dynamically down-regulated EpCAM expression. In a mouse model of human breast cancer using EpCAM positive and negative cell lines, the number of CTCs captured correlated positively with the size of the primary tumor and was independent of their EpCAM expression. Furthermore, in a syngeneic mouse model of lung cancer using cell lines with differential metastasis capability, CTCs were captured from all mice with detectable primary tumors independent of the cell lines' metastatic ability.

CONCLUSIONS

The microfluidic CTC capture chip using a novel nanoroughened glass substrate is broadly applicable to capturing heterogeneous CTC populations of clinical interest independent of their surface marker expression and metastatic propensity. We were able to capture CTCs from a non-metastatic lung cancer model, demonstrating the potential of the chip to collect the entirety of CTC populations including subgroups of distinct biological and phenotypical properties. Further exploration of the biological potential of metastatic and presumably non-metastatic CTCs captured using the microfluidic chip will yield insights into their relevant differences and their effects on tumor progression and cancer outcomes.