Challenges in circulating tumor cell detection by the CellSearch system

A survey of electrokinetically-driven microfluidics for cancer cells manipulation

Cancer is one of the leading causes of annual deaths worldwide, accounting for nearly 10 million deaths each year. Metastasis, the process by which cancer spreads across the patient's body, is the main cause of death in cancer patients. Because the rising trend observed in statistics of new cancer cases and cancer-related deaths does not allow for an optimistic viewpoint on the future-in relation to this terrible disease-the scientific community has sought methods to enable early detection of cancer and prevent the apparition of metastatic tumors. One such method is known as liquid biopsy, wherein a sample is taken from a bodily fluid and analyzed for the presence of CTCs or other cancer biomarkers (e.g., growth factors). With this objective, interest is growing by year in electrokinetically-driven microfluidics applied for the concentration, capture, filtration, transportation, and characterization of CTCs. Electrokinetic techniques-electrophoresis, dielectrophoresis, electrorotation, and electrothermal and EOF-have great potential for miniaturization and integration with electronic instrumentation for the development of point-of-care devices, which can become a tool for early cancer diagnostics and for the design of personalized therapeutics. In this contribution, we review the state of the art of electrokinetically-driven microfluidics for cancer cells manipulation.

Magnetic Particles for CTC Enrichment

Simple Summary

For the enrichment of very rare cells, such as Circulating Tumor Cells (CTCs), immunomagnetic enrichment is frequently used. For this purpose, magnetic nanoparticles (MNPs) coated with specific antibodies directed against cancer cells are used. In this review, we look at the properties such a particle needs to have in order to be used successfully, and describe the different methods used in the production of such a particle as well as the methods for their separation. Additionally, an overview is given of the antibodies that could potentially be used for this purpose.

Abstract

Here, we review the characteristics and synthesis of magnetic nanoparticles (MNPs) and place these in the context of their usage in the immunomagnetic enrichment of Circulating Tumor Cells (CTCs). The importance of the different characteristics is explained, the need for a very specific enrichment is emphasized and different (commercial) magnetic separation techniques are shown. As the specificity of an MNP is in a large part dependent on the antibody coated onto the particle, different strategies in the coupling of specific antibodies as well as an overview of the available antibodies is given.

On-Chip Multiple Particle Velocity and Size Measurement Using Single-Shot Two-Wavelength Differential Image Analysis

Precise and quick measurement of samples' flow velocities is essential for cell sorting timing control and reconstruction of acquired image-analyzed data. We developed a simple technique for the single-shot measurement of flow velocities of particles simultaneously in a microfluidic pathway. The speed was calculated from the difference in the particles' elongation in an acquired image that appeared when two wavelengths of light with different irradiation times were applied. We ran microparticles through an imaging flow cytometer and irradiated two wavelengths of light with different irradiation times simultaneously to those particles. The mixture of the two wavelength transmitted lights was divided into two wavelengths, and the images of the same microparticles for each wavelength were acquired in a single shot. We estimated the velocity from the difference of its elongation divided by the difference of irradiation time by comparing these two images. The distribution of polystyrene beads' velocity was parabolic and highest at the center of the flow channel, consistent with the expected velocity distribution of the laminar flow. Applying the calculated velocity, we also restored the accurate shapes and cross-sectional areas of particles in the images, indicating this simple method for improving of imaging flow cytometry and cell sorter for diagnostic screening of circulating tumor cells.

Efficient Propagation of Circulating Tumor Cells: A First Step for Probing Tumor Metastasis

Simple Summary

Cancer metastasis is responsible for most cancer-associated death. During metastasis, cells that escape the primary tumor into the circulatory system are known as circulating tumor cells. Previous attempts at growing circulating tumor cells in the lab have been hindered by low success rates. Using the novel system first reported here, we demonstrate a 100% (12/12 samples) success rate in culturing circulating tumor cells from metastatic breast cancer patients. Once propagated, we characterized the expression profiles of our cultures, verifying their origins as breast cancer cells. Furthermore, exploratory analysis identifies several key pathways and genes previously known to be associated with breast cancer progression and metastasis. Finally, we demonstrate that cultures grown in the presence of CD45⁺ cells exhibited higher growth potential ex vivo. Based on this system, we suggest that a reconsideration of the parameters for circulating tumor cell isolation should be undertaken.

Abstract

Circulating tumor cells (CTCs) represent a unique population of cells that can be used to investigate the mechanistic underpinnings of metastasis. Unfortunately, current technologies designed for the isolation and capture of CTCs are inefficient. Existing literature for in vitro CTC cultures report low (6−20%) success rates. Here, we describe a new method for the isolation and culture of CTCs. Once optimized, we employed the method on 12 individual metastatic breast cancer patients and successfully established CTC cultures from all 12 samples. We demonstrate that cells propagated were of breast and epithelial origin. RNA-sequencing and pathway analysis demonstrated that CTC cultures were distinct from cells obtained from healthy donors. Finally, we observed that CTC cultures that were associated with CD45⁺ leukocytes demonstrated higher viability. The presence of CD45⁺ leukocytes significantly enhanced culture survival and suggests a re-evaluation of the methods for CTC isolation and propagation. Routine access to CTCs is a valuable resource for identifying genetic and molecular markers of metastasis, personalizing the treatment of metastatic cancer patients and developing new therapeutics to selectively target metastatic cells.

Non-Invasive Biomarkers for Early Detection of Breast Cancer

Breast cancer is the most common cancer in women worldwide. Accurate early diagnosis of breast cancer is critical in the management of the disease. Although mammogram screening has been widely used for breast cancer screening, high false-positive and false-negative rates and radiation from mammography have always been a concern. Over the last 20 years, the emergence of "omics" strategies has resulted in significant advances in the search for non-invasive biomarkers for breast cancer diagnosis at an early stage. Circulating carcinoma antigens, circulating tumor cells, circulating cell-free tumor nucleic acids (DNA or RNA), circulating microRNAs, and circulating extracellular vesicles in the peripheral blood, nipple aspirate fluid, sweat, urine, and tears, as well as volatile organic compounds in the breath, have emerged as potential non-invasive diagnostic biomarkers to supplement current clinical approaches to earlier detection of breast cancer. In this review, we summarize the current progress of research in these areas.

Integrated system for detection and molecular characterization of circulating tumor cells

Circulating tumor cells (CTCs) invade blood vessels in solid tumors and promote metastases by circulating in the blood. CTCs are thus recognized as targets for liquid biopsy and can provide useful information for design of treatments. This diagnostic approach must consider not only the number of CTCs but also their molecular and genetic characteristics. For this purpose, use of devices that enrich CTCs independent of these characteristics and detectors that recognize various CTC characteristics is essential. In the present study, we developed a CTC detection system comprising ClearCell FX and ImageStream Mark II. We clarified the analytical performance of this system by evaluating recovery rate, lower limits of detection, and linearity. These parameters are critical for detecting rare cells, such as CTCs. We tested these parameters using three cell lines with different expression levels of the epithelial marker-epithelial cell adhesion molecule (EpCAM) and spiked these cells into whole-blood samples from healthy donors. The average recovery rate and lower limit of detection were approximately 40% and five cells/7.5 mL of whole blood, respectively. High linearity was observed for all evaluated samples. We also evaluated the ability of the system to distinguish between normal and abnormal cells based on protein expression levels and gene amplification and found that the system can identify abnormal cells using these characteristics. The CTC detection system thus displays the ability to distinguish specific characteristics of CTC, thereby providing valuable information for cancer treatment.

Molecular and Functional Characterization of Circulating Tumor Cells: From Discovery to Clinical Application

BACKGROUND

One of the objectives for the liquid biopsy is to become a surrogate to tissue biopsies in diagnosis of cancer as a minimally invasive method, with clinical utility in real-time follow-ups of patients. To achieve this goal, it is still necessary to achieve a better understanding of the mechanisms of cancer and the biological principles that govern its behavior, particularly with regard to circulating tumor cells (CTCs).

CONTENT

The isolation, enumeration, detection, and characterization of CTCs have already proven to provide relevant clinical information about patient prognosis and treatment prediction. Moreover, CTCs can be analyzed at the genome, proteome, transcriptome, and secretome levels and can also be used for functional studies in in vitro and in vivo models. These features, taken together, have made CTCs a very valuable biosource.

SUMMARY

To further advance the field and discover new clinical applications for CTCs, several studies have been performed to learn more about these cells and better understand the biology of metastasis. In this review, we describe the recent literature on the topic of liquid biopsy with particular focus on the biology of CTCs.

Precision Detection Technology: Equipping Precision Oncology with Wings

In recent years, precision medical detection techniques experienced a rapid transformation from low-throughput to high-throughput genomic sequencing, from multicell promiscuous detection to single-cell precision sequencing. The emergence of liquid biopsy technology has compensated for the many limitations of tissue biopsy, leading to a tremendous transformation in precision detection. Precision detection techniques contribute to monitoring disease development more closely, evaluating therapeutic effects more scientifically, and developing new targets and new drugs. In the future, the role of precision detection and the joint detection in epigenetics, rare gene detection, individualized targeted therapy, and multigene targeted drug combination therapy should be extensively explored. This article reviews the changes in precision medical detection technology in the era of precision medicine, as well as the development, clinical application, and future challenges of liquid biopsy.

Circulating tumor cells are an indicator for the administration of adjuvant transarterial chemoembolization in hepatocellular carcinoma: A single-center, retrospective, propensity-matched study

Background

High rates of postoperative tumor recurrence contribute to poor outcome in hepatocellular carcinoma (HCC). Here, we investigated whether circulating tumor cells (CTCs) status can predict the benefit of adjuvant transcatheter arterial chemoembolization (TACE) in patients with HCC.

Methods

The retrospective study enrolled 344 HCC patients with preoperative CTCs analysis. Clinical outcomes including recurrence and survival were compared between those who received and who did not receive adjuvant TACE. Similar comparisons were made for patients stratified according to CTC status (CTC‐negative [CTC = 0], n = 123; CTC‐positive [CTC ≥ 1], n = 221). Propensity score matching (PSM) strategy was adopted to offset differences between two groups.

Results

In the study cohort as a whole or in CTC‐negative cohort, there were no observable differences in overall survival (OS) or time to recurrence (TTR) between TACE and control group (P > .05). In CTC‐positive patients, PSM generated 64 patient pairs, and patients with adjuvant TACE had significantly better clinical outcomes (OS: not reached vs 36.4 months, P < .001; TTR: 45.8 vs 9.8 months, P < .001). Adjuvant TACE significantly reduced early recurrence (≤2 years) (64.1% vs 31.7%, P < .001) in CTC‐positive patients. Notably, adjuvant TACE influenced TTR and OS even in subgroups of CTC‐positive patients with low risk of recurrence according to traditional evaluation.

Conclusions

Preoperative CTC status could serve as an indicator for the administration of adjuvant TACE in HCC patients. Adjuvant TACE benefits CTC‐positive HCC patients mainly by reducing early recurrence.

Circulating tumour cells: a broad perspective

Circulating tumour cells (CTCs) have recently been identified as valuable biomarkers for diagnostic and prognostic evaluations, as well for monitoring therapeutic responses to treatments. CTCs are rare cells which may be present as one CTC surrounded by approximately 1 million white blood cells and 1 billion red blood cells per millilitre of peripheral blood. Despite the various challenges in CTC detection, considerable progress in detection methods have been documented in recent times, particularly for methodologies incorporating nanomaterial-based platforms and/or integrated microfluidics. Herein, we summarize the importance of CTCs as biological markers for tumour detection, highlight their mechanism of cellular invasion and discuss the various challenges associated with CTC research, including vulnerability, heterogeneity, phenotypicity and size differences. In addition, we describe nanomaterial agents used for electrochemistry and surface plasmon resonance applications, which have recently been used to selectively capture cancer cells and amplify signals for CTC detection. The intrinsic properties of nanomaterials have also recently been exploited to achieve photothermal destruction of cancer cells. This review describes recent advancements and future perspectives in the CTC field.

Clinical value and feasibility of ISET in detecting circulating tumor cells in early breast cancer

Background

Patients with operable breast cancer have a better prognosis for recovery. However, once distant organ metastasis occurs, the chance of a long-term survival or a cure is limited. The collection and counting of circulating tumor cells (CTCs) by reliable detection techniques are of increasing importance in the diagnosis of early metastasis and prognosis of disease progression. Isolation by size of epithelial tumor cells (ISET) has the advantage of simplicity of operation and high homogeneity. It is practical for large-scale clinical detection showing cell abundance. The value of ISET in the detection of circulating breast cancers in the blood has not been determined. The purpose of this study is to explore the feasibility of applying ISET to detect CTCs by determining the detection rate of ISET in operable breast cancer and by evaluating the correlation between detection rate, cell count and clinical factors such as molecular typing and pathological staging.

Methods

The experiment included 193 breast cancer patients who were diagnosed by core needle biopsy before the operation. 10 mL of venous blood was collected from the patients preoperatively, and CTCs in their blood samples were counted and analyzed by ISET.

Results

Patients were divided into groups according to pathology and immunohistochemistry. The overall detection rate of CTCs by ISET was 41.24%. The detection rate, the number of overall CTCs and the average number of CTCs in each group were analyzed individually. No significant differences were observed between the different groups.

Conclusions

Although ISET has a relatively good detection rate for circulating breast cancer cells, it fails to provide more information on pathological staging, molecular classification and so forth.

Quantification of Protein Secretion from Circulating Tumor Cells in Microfluidic Chambers

Cancer cells can be released from a cancerous lesion and migrate into the circulatory system, from whereon they may form metastases at distant sites. Today, it is possible to infer cancer progression and treatment efficacy by determining the number of circulating tumor cells (CTCs) in the patient's blood at multiple time points; further valuable information about CTC phenotypes remains inaccessible. In this article, a microfluidic method for integrated capture, isolation, and analysis of membrane markers as well as quantification of proteins secreted by single CTCs and CTC clusters is introduced. CTCs are isolated from whole blood with extraordinary efficiencies above 95% using dedicated trapping structures that allow co-capture of functionalized magnetic beads to assess protein secretion. The patform is tested with multiple breast cancer cell lines spiked into human blood and mouse-model-derived CTCs. In addition to immunostaining, the secretion level of granulocyte growth stimulating factor (G-CSF), which is shown to be involved in neutrophil recruitment, is quantified The bead-based assay provides a limit of detection of 1.5 ng mL^-1 or less than 3700 molecules per cell. Employing barcoded magnetic beads, this platform can be adapted for multiplexed analysis and can enable comprehensive functional CTC profiling in the future.

Patient-Derived In Vitro Models for Drug Discovery in Colorectal Carcinoma

Lack of relevant preclinical models that reliably recapitulate the complexity and heterogeneity of human cancer has slowed down the development and approval of new anti-cancer therapies. Even though two-dimensional in vitro culture models remain widely used, they allow only partial cell-to-cell and cell-to-matrix interactions and therefore do not represent the complex nature of the tumor microenvironment. Therefore, better models reflecting intra-tumor heterogeneity need to be incorporated in the drug screening process to more reliably predict the efficacy of drug candidates. Classic methods of modelling colorectal carcinoma (CRC), while useful for many applications, carry numerous limitations. In this review, we address the recent advances in in vitro CRC model systems, ranging from conventional CRC patient-derived models, such as conditional reprogramming-based cell cultures, to more experimental and state-of-the-art models, such as cancer-on-chip platforms or liquid biopsy.

Nanotherapeutics for Antimetastatic Treatment

Tumor metastases, that is, the development of secondary tumors in organs distant from the primary tumor, and their treatment remain a serious problem in cancer therapy. The unique challenges for tracking and treating tumor metastases lie in the small size, high heterogeneity, and wide dispersion to distant organs of metastases. Recently, nanomedicines, with the capacity to precisely deliver therapeutic agents to both primary and secondary tumors, have demonstrated many potential benefits for metastatic cancer theranostics. Given the remarkable progression in emerging nanotherapeutics for antimetastatic treatment, it is timely to summarize the latest advances in this field. This review highlights the rationale, advantages, and challenges for integrating biomedical nanotechnology with cancer biology to develop antimetastatic nanotherapeutics.

Biomimetic immunomagnetic gold hybrid nanoparticles coupled with inductively coupled plasma mass spectrometry for the detection of circulating tumor cells

Immunomagnetic beads are important tools for the isolation and detection of circulating tumor cells (CTCs). However, the current immunomagnetic bead technique provides poor CTC separation purity due to nonspecific binding of background cells. Furthermore, immunomagnetic beads have not been appropriately functionalized for enabling CTC analysis and quantification. In this work, bimetallic magnetic gold nanoparticles were prepared and coated with leukocyte membranes to form leukocyte membrane-camouflaged nanoparticles. After conjugation with the antibody of epithelial cell adhesion molecule (EpCAM), the biomimetic immunomagnetic gold nanoparticles (CM-Fe₃O₄@Au-Ab) showed a high specific recognition ability on mock (EpCAM-positive) CTCs and a reduced interaction with leukocytes. We subsequently optimized the conditions for CTC separation, including the concentration of nanoparticles and the incubation time. Under the optimized conditions, CM-Fe₃O₄@Au-Ab exhibited high CTC capture efficiency with negligible background cell binding in mock clinical blood samples. More importantly, gold probes were tagged on the surface of these separated CTCs. When coupled with ICP-MS analysis, the number of CTCs and gold signals exhibited a good linear relationship, and a low limit of detection was obtained, enabling us to estimate the number of CTCs in blood samples. Hence, we expected that CM-Fe₃O₄@Au-Ab could provide an opportunity to surmount the limitations of current CTC detection.

Direct comparison of size-dependent versus EpCAM-dependent CTC enrichment at the gene expression and DNA methylation level in head and neck squamous cell carcinoma

We directly compared two different approaches used for Circulating Tumor Cell (CTC) isolation, a size-dependent microfluidic system versus an EpCAM-dependent positive selection for downstream molecular characterization of CTC both at the gene expression and DNA methylation level in Head and Neck Squamous Cell Carcinoma (HNSCC). A size-dependent microfluidic device (Parsortix, ANGLE) and an EpCAM-dependent positive immune-magnetic isolation procedure were applied in parallel, using 10 mL PB from 50 HNSCC patients and 18 healthy donors. Total RNA was isolated from enriched CTCs and RT-qPCR was used to study the expression levels of CK-19, PD-L1, EGFR, TWIST1, CDH2 and B2M (reference gene). Real time methylation specific PCR (MSP) was used to study the methylation status of RASSF1A and MLL3 genes. In identical blood draws, the label-free size-dependent CTC-isolation system was superior in terms of sensitivity when compared to the EpCAM-dependent CTC enrichment, since a significantly higher percentage of identical PB samples was found positive at the gene expression and DNA methylation level, while the specificity was not affected. Our results indicate that future studies focused on the evaluation of clinical utility of CTC molecular characterization in HNSCC should be based on size-dependent enrichment approaches.

Microfluidics and Nanomaterial-based Technologies for Circulating Tumor Cell Isolation and Detection

Cancer has been one of the leading causes of death globally, with metastases and recurrences contributing to this result. The detection of circulating tumor cells (CTCs), which have been implicated as a major population of cells that is responsible for seeding and migration of tumor sites, could contribute to early detection of metastasis and recurrences, consequently increasing the chances of cure. This review article focuses on the current progress in microfluidics technology in CTCs diagnostics, extending to the use of nanomaterials and surface modification techniques for diagnostic applications, with an emphasis on the importance of integrating microchannels, nanomaterials, and surface modification techniques in the isolating and detecting of CTCs.

Clinical Relevance of Circulating Tumor Cells in Esophageal Cancer Detected by a Combined MACS Enrichment Method

INTRODUCTION

Current modalities to predict tumor recurrence and survival in esophageal cancer are insufficient. Even in lymph node-negative patients, a locoregional and distant relapse is common. Hence, more precise staging methods are needed. So far, only the CellSearch system was used to detect circulating tumor cells (CTC) with clinical relevance in esophageal cancer patients. Studies analyzing different CTC detection assays using advanced enrichment techniques to potentially increase the sensitivity are missing.

METHODS

In this single-center, prospective study, peripheral blood samples from 90 esophageal cancer patients were obtained preoperatively and analyzed for the presence of CTCs by Magnetic Cell Separation (MACS) enrichment (combined anti-cytokeratin and anti-epithelial cell adhesion molecules (EpCAM)), with subsequent immunocytochemical staining. Data were correlated with clinicopathological parameters and patient outcomes.

RESULTS

CTCs were detected in 25.6% (23/90) of the patients by combined cytokeratin/EpCAM enrichment (0-150 CTCs/7.5 mL). No significant correlation between histopathological parameters and CTC detection was found. Survival analysis revealed that the presence of more than two CTCs correlated with significantly shorter overall survival (OS) and progression-free survival (PFS).

CONCLUSION

With the use of cytokeratin as an additional enrichment target, the CTC detection rate in esophageal cancer patients can be elevated and displays the heterogeneity of cytokeratin (CK) and EpCAM expression. The presence of >2CTCs correlated with a shorter relapse-free and overall survival in a univariate analysis, but not in a multivariate setting. Moreover, our results suggest that the CK7/8+/EpCAM+ or CK7/8+/EpCAM- CTC subtype does not lead to an advanced tumor staging tool in non-metastatic esophageal cancer (EC) patients.

Will traditional biopsy be substituted by radiomics and liquid biopsy for breast cancer diagnosis and characterisation?

The diagnosis of breast cancer currently relies on radiological and clinical evaluation, confirmed by histopathological examination. However, such approach has some limitations as the suboptimal sensitivity, the long turnaround time for recall tests, the invasiveness of the procedure and the risk that some features of target lesions may remain undetected, making re-biopsy a necessity. Recent technological advances in the field of artificial intelligence hold promise in addressing such medical challenges not only in cancer diagnosis, but also in treatment assessment, and monitoring of disease progression. In the perspective of a truly personalised medicine, based on the early diagnosis and individually tailored treatments, two new technologies, namely radiomics and liquid biopsy, are rising as means to obtain information from diagnosis to molecular profiling and response assessment, without the need of a biopsied tissue sample. Radiomics works through the extraction of quantitative peculiar features of cancer from radiological data, while liquid biopsy gets the whole of the malignancy's biology from something as easy as a blood sample. Both techniques hopefully will identify diagnostic and prognostic information of breast cancer potentially reducing the need for invasive (and often difficult to perform) biopsies and favouring an approach that is as personalised as possible for each patient. Nevertheless, such techniques will not substitute tissue biopsy in the near future, and even in further times they will require the aid of other parameters to be correctly interpreted and acted upon.

Tumor-Cell-Macrophage Fusion Cells as Liquid Biomarkers and Tumor Enhancers in Cancer

Although molecular mechanisms driving tumor progression have been extensively studied, the biological nature of the various populations of circulating tumor cells (CTCs) within the blood is still not well understood. Tumor cell fusion with immune cells is a longstanding hypothesis that has caught more attention in recent times. Specifically, fusion of tumor cells with macrophages might lead to the development of metastasis by acquiring features such as genetic and epigenetic heterogeneity, chemotherapeutic resistance, and immune tolerance. In addition to the traditional FDA-approved definition of a CTC (CD45-, EpCAM+, cytokeratins 8+, 18+ or 19+, with a DAPI+ nucleus), an additional circulating cell population has been identified as being potential fusions cells, characterized by distinct, large, polymorphonuclear cancer-associated cells with a dual epithelial and macrophage/myeloid phenotype. Artificial fusion of tumor cells with macrophages leads to migratory, invasive, and metastatic phenotypes. Further studies might investigate whether these have a potential impact on the immune response towards the cancer. In this review, the background, evidence, and potential relevance of tumor cell fusions with macrophages is discussed, along with the potential role of intercellular connections in their formation. Such fusion cells could be a key component in cancer metastasis, and therefore, evolve as a diagnostic and therapeutic target in cancer precision medicine.

Epithelial-mesenchymal transition status of circulating tumor cells in breast cancer and its clinical relevance

Objective: Circulating tumor cells (CTCs) play a critical role in cancer metastasis, but their prevalence and significance remain unclear. This study attempted to track the epithelial-mesenchymal transition (EMT) status of CTCs in breast cancer patients and investigate their clinical relevance. Methods: In this study, the established negFACS-IF:E/M platform was applied to isolate rare CTCs and characterize their EMT status in breast cancer. A total of 89 breast cancer patients were recruited, including stage 0-III (n = 60) and late stage (n = 29) cases. Results: Using the negFACS-IF:E/M platform, it was found that in human epidermal growth factor receptor 2 (HER2)+ patients, mesenchymal CTCs usually exhibited a high percentage of HER2+ cells. Stage IV breast cancer patients had considerably more CTCs than stage 0-III patients. Among stage 0-III breast cancers, the HER2 subtype included a significantly higher percentage of mesenchymal and biphenotypic (epithelial and mesenchymal) CTCs than the luminal A or B subtypes. Among stage IV patients, CTCs were predominantly epithelial in cases with local recurrence and were more mesenchymal in cases with distant metastasis. By applying a support vector machine (SVM) algorithm, the EMT status of CTCs could distinguish between breast cancer cases with metastasis/local recurrence and those without recurrence. Conclusions: The negFACS-IF:E/M platform provides a flexible and generally acceptable method for the highly sensitive and specific detection of CTCs and their EMT traits in breast cancer. This study demonstrated that the EMT status of CTCs had high clinical relevance in breast cancer, especially in predicting the distant metastasis or local recurrence of breast cancer.

Post-enrichment circulating tumor cell detection and enumeration via deformability impedance cytometry

Circulating tumor cells (CTCs) in blood can provide valuable information when detecting, diagnosing, and monitoring cancer. This paper describes a system that consists of a constriction-based microfluidic sensor with embedded electrodes that can detect and enumerate cancer cells in blood. The biosensor measures impedance in terms of magnitude and phase at multiple frequencies as cells transit through the constriction channel. Cancer cells deform as they move through while blood cells remain intact, thus generating differential impedance profiles that can be used for detecting and counting CTCs. Two versions of this device are reported, one where the electrodes are embedded into the disposable microfluidic channel, and the other in which the disposable chip is externally fixed to a reusable substrate housing the electrodes. Both configurations were tested by spiking breast or prostate cancer cells into murine blood, and both detected all tumor cells passing through the narrow channels while being able to differentiate between the two cell lines. The chip in its current format has a throughput of 1 μL/min. While the throughput is scalable by integrating more constriction channels in parallel, the presented assay is intended for post-enrichment label-free enumeration and characterization of CTCs.

Determination of the optimal detection time of circulating tumor cells for the postoperative monitoring of colorectal cancer

Circulating tumor cells (CTCs) are widely used in cancer screening and monitoring. The present study focused on investigating the optimal time for the postoperative CTC detection in patients with colorectal cancer (CRC) to obtain more accurate results and facilitate subsequent treatment. By subtraction enrichment immunofluorescence in situ hybridization detection of CTCs, the present study demonstrated that different postoperative detection times in CRC substantially influenced the CTC numbers. In total, 134 subjects were enrolled. Among 10 healthy individuals and 20 preoperative patients with CRC, no CTCs were identified in the healthy subjects, and CTCs were detected in 85% (17/20) of the preoperative patients. In total, 104 postoperative patients with CRC (53 males and 51 females) with a mean average age of 57.63 years were studied. The total CTC detection rate was 81.73% (85/104) and the mean average CTC numbers in patients with tumor stage (T) T1, T2, T3 and T4 were 4.00, 3.33, 5.90 and 5.64 per 7.50 ml of peripheral blood, respectively. The CTC number trends in these four tumor stages within 5, 6, 7 and 10 postoperative days were variable, and were the most stable at 7 days. Gradual upward trends in CTC numbers were observed after 5, 6 and 7 postoperative days, and this upward trend was more obvious after 7 days. Overall, the findings of the present study suggest that CTC detection in CRC should be performed after at least 7 postoperative days rather than within 7 postoperative days.

Combined use of circulating tumor cells and salivary mRNA to detect non-small-cell lung cancer

Liquid biopsy is an emerging technique for noninvasive detection of various cancers. Majority of liquid biopsy tests still, however, use solitary type of biomarkers with unsatisfactory sensitivity and specificity. To this end, a combined approach of circulating tumor cells (CTCs) and salivary mRNA biomarkers was evaluated for discriminating non-small-cell lung cancer (NSCLC) from healthy controls.Our study included a discovery phase to find multiple biomarkers, and an independent validation phase to confirm the applicability of the selected biomarkers. In the discovery phase, CTC level in blood and 5 mRNA biomarkers in saliva (i.e., CCNI, Epidermal growth factor receptor [EGFR], FGF19, FRS2, and GREB1) were measured for 140 NSCLC patients and 140 healthy controls, followed by developing a predictive model. Next, this panel of biomarkers was applied to another patient cohort consisted of 60 patients with NSCLC and 60 healthy controls in the validation phase.We found that our novel biomarker panel could differentiate patients with NSCLC from healthy controls with high sensitivity (92.1%) and high specificity (92.9%) in the discovery phase. In the validation phase, we achieved sensitivity of 88.3% and specificity of 90.0%.To our best knowledge, it is the first time that a combined use of CTC and salivary mRNA biomarkers were applied for noninvasive detection of NSCLC.

Antibody-Free Hydrogel with the Synergistic Effect of Cell Imprinting and Boronate Affinity: Toward the Selective Capture and Release of Undamaged Circulating Tumor Cells

The selective and highly efficient capture of circulating tumor cells (CTCs) from blood and their subsequent release without damage are very important for the early diagnosis of tumors and for understanding the mechanism of metastasis. Herein, a universal strategy is proposed for the fabrication of an antibody-free hydrogel that has a synergistic effect by featuring microinterfaces obtained by cell imprinting and molecular recognition conferred by boronate affinity. With this artificial antibody, highly efficient capture of human hepatocarcinoma SMMC-7721 cells is achieved: as many as 90.3 ± 1.4% (n = 3) cells are captured when 1 × 10⁵ SMMC-7721 cells are incubated on a 4.5 cm² hydrogel, and 99% of these captured cells are subsequently released without any loss of proliferation ability. In the presence of 1000 times as many nontarget cells, namely, leukaemia Jurkat cells, the SMMC-7721 cells can be captured with an enrichment factor as high as 13.5 ± 3.2 (n = 3), demonstrating the superior selectivity of the artificial antibody for the capture of the targeted CTCs. Most importantly, the SMMC-7721 cells can be successfully captured even when spiked into whole blood, indicating the great promise of this approach for the further molecular characterization of CTCs.

Nanoscale metal-organic frameworks in detecting cancer biomarkers

Following the efficient performance of metal-organic frameworks (MOFs) as recognition elements in gas sensors, biosensors based on MOFs are now being investigated to capture and quantify potential cancer biomarkers, such as circulating tumor cells (CTCs), nucleic acids and proteins. The current status of MOF-based biosensors in the detection of early stages of cancer is in its infancy, although it has significantly emerged since the beginning of this decade. That said, salient research has been conducted in the past five years to utilize the distinctive porous crystalline structure of MOFs for highly sensitive and selective detection of cancer biomarkers. In this pursual, MOFs designed with bimetallic assembly, doped with magnetic nanoparticles, coated with polymers, and even conjugated with peptides or oligonucleotides have shown promising outcomes in detecting CTCs, nucleic acids and proteins. In particular, aptamer-conjugated MOFs are able to perform at a lower limit of detection down to the femtomolar, implying their efficacy for the point of care testing in clinical trials. In this way, aptasensors based on aptamer-conjugated MOFs present a newer sub-branch, to be coined as a MOFTA sensor in the current review. Considering the emerging progress and promising outcomes of MOFTA sensors as well as a variety of MOF-based techniques of detecting cancer biomarkers, this review will highlight their significant advances and related aspects in the recent five years on the context of detecting CTCs, nucleic acids and proteins for the early-stage detection of cancer.

Circulating Tumor Cells as a Marker of Disseminated Disease in Patients with Newly Diagnosed High-Risk Prostate Cancer

The aim of this study was to investigate whether the enumeration of circulating tumor cells (CTCs) in blood can differentiate between true localized and metastatic prostate cancer. A cross-sectional study of 104 prostate cancer patients with newly diagnosed high-risk prostate cancer was conducted. In total, 19 patients presented metastatic disease and 85 were diagnosed with localized disease. Analyses included intergroup comparison of CTC counts, determined using the CellSearch® system, EPISPOT assay and GILUPI CellCollector®, and ROC analysis verifying the accuracy of CTC count as a maker of disseminated prostate cancer. The vast majority (94.7%) of patients with advanced-stage cancer tested positively for CTCs in at least one of the assays. However, significantly higher CTC counts were determined with the CellSearch® system compared to EPISPOT assay and GILUPI CellCollector®. Identification of ≥4 CTCs with the CellSearch® system was the most accurate predictor of metastatic disease (sensitivity 0.500; specificity 0.900; AUC (95% CI) 0.760 (0.613-0.908). Furthermore, we tried to create a model to enhance the specificity and sensitivity of metastatic prediction with CTC counts by incorporating patient's clinical data, including PSA serum levels, Gleason score and clinical stage. The composite biomarker panel achieved the following performance: sensitivity, 0.611; specificity, 0.971; AUC (95% CI), 0.901 (0.810-0.993). Thus, although the sensitivity of CTC detection needs to be further increased, our findings suggest that high CTC counts might contribute to the identification of high-risk prostate cancer patients with occult metastases at the time of diagnosis.

Design of DNA Aptamer-Functionalized Magnetic Short Nanofibers for Efficient Capture and Release of Circulating Tumor Cells

The isolation of viable circulating tumor cells (CTCs) from blood is of paramount significance for early stage detection and individualized therapy of cancer. Currently, CTCs isolated by conventional magnetic separation methods are tightly coated with magnetic materials even after attempted coating removal treatments, which is not conducive for subsequent analysis of CTCs. Herein, we developed DNA aptamer-functionalized magnetic short nanofibers (aptamer-MSNFs) for efficient capture and release of CTCs. In our work, polyethylenimine (PEI)-stabilized Fe₃O₄ nanoparticles with a mean diameter of 22.6 nm were first synthesized and encapsulated within PEI/poly(vinyl alcohol) nanofibers via a blended electrospinning process. After a homogenization treatment to acquire the MSNFs, surface conjugation of the DNA aptamer was performed through thiol-maleimide coupling. The formed aptamer-MSNFs, with a mean diameter of 350 nm and an average length of 9.6 μm, display a saturated magnetization of 12.3 emu g^-1, are capable of specifically capturing cancer cells with an efficiency of 87%, and enable the nondestructive release of cancer cells with a release efficiency of 91% after nuclease treatment. In particular, the prepared aptamer-MSNFs displayed a significantly higher release efficiency than commercial magnetic beads. The designed aptamer-MSNFs may hold great promise for CTC capture and release as well as for other cell sorting applications.

Methodology for the Isolation and Analysis of CTCs

The majority of deaths related to breast cancer are caused by metastasis. Understanding the process of metastasis is key to achieve a reduction on breast cancer mortality. Currently, liquid biopsies are gaining attention in this regard. Circulating tumor cells (CTCs), an important component of liquid biopsies, are cells shed from primary tumor that disseminate to blood circulation being responsible of distal metastasis. Hence, the study CTCs is a promising alternative to monitor the progress of metastasis disease and can be used for early diagnosis of cancers as well as for earlier assessment of cancer recurrence and therapy efficacy. Despite their clinical interest, CTC analysis is not recommended by oncology guidelines so far. The main reason is that there is no gold standard technology for CTCs isolation and most of the current technologies are not yet validated for clinical use. In this chapter we will focus on the most relevant technologies for CTC isolation based on their properties and depending on whether it is a positive or negative selection. We also describe each technology based on its potential use and its relevance in breast cancer. The chapter also contains a future perspective including the challenges and requirements of CTC detection.

Analytical validation of the CellMax platform for early detection of cancer by enumeration of rare circulating tumor cells

The CellMax (CMx®) platform was developed to enrich for epithelial circulating tumor cells (CTCs) in the whole blood. This report provides assay performance data, including accuracy, linearity, limit of blank, limit of detection (LOD), specificity, and precision of enumeration of cancer cell line cells (CLCs) spiked in cell culture medium or healthy donor blood samples. Additionally, assay specificity was demonstrated in 32 young healthy donors and clinical feasibility was demonstrated in a cohort of 47 subjects consisting of healthy donors and patients who were colonoscopy verified to have colorectal cancer, adenomas, or a negative result. The CMx platform demonstrated high accuracy, linearity, and sensitivity for the enumeration of all CLC concentrations tested, including the extremely low range of 1 to 10 cells in 2 mL of blood, which is most relevant for early cancer detection. Theoretically, the assay LOD is 0.71 CTCs in 2 mL of blood. The analytical specificity was 100% demonstrated using 32 young healthy donor samples. We also demonstrated precision across multiple days and multiple operators, with good reproducibility of recovery efficiency. In a clinical feasibility study, the CMx platform identified 8 of 10 diseased subjects as positive (80% clinical sensitivity) and 4 of 5 controls as negative (80% clinical specificity). We also compared processing time and transportation effects for similar blood samples from two different sites and assessed an artificial intelligence-based counting method. Finally, unlike other platforms for which captured CTCs are retained on ferromagnetic beads or tethered to the slide surface, the CMx platform's unique airfoam-enabled release of CTCs allows captured cells to be transferred from a microfluidic chip to an Eppendorf tube, enabling a seamless transition to downstream applications such as genetic analyses and live cell manipulations.

Liquid Biopsy in Non-Small Cell Lung Cancer: Highlights and Challenges

Non-small cell lung cancer is one leading cause of death worldwide, and patients would greatly benefit from an early diagnosis. Since targeted and immunotherapies have emerged as novel approaches for more tailored treatments, repeated assessments of the tumor biology have become pivotal to drive clinical decisions. Currently, tumor tissue biopsy is the gold standard to investigate potentially actionable biomarkers, but this procedure is invasive and may prove inadequate to represent the whole malignancy. In this regard, liquid biopsy represents a minimally invasive and more comprehensive option for early detection and investigation of this tumor. Today, cell-free DNA is the only approved circulating marker to select patients for a targeted therapy. Conversely, the other tumor-derived markers (i.e., circulating tumor cells, miRNAs, exosomes, and tumor educated platelets) are still at a pre-clinical phase, although they show promising results for their application in screening programs or as prognostic/predictive biomarkers. The main challenges for their clinical translation are the lack of reliable cutoffs and, especially for miRNAs, the great variability among the studies. Moreover, no established tool has been approved for circulating tumor cells and exosome isolation. Finally, large prospective clinical trials are mandatory to provide evidence of their clinical utility.

Circulating Tumor Cells in Gastrointestinal Cancers: Current Status and Future Perspectives

Circulating tumor cells (CTCs), which are now defined as the "break away" cancer cells that derive from primary- or metastatic-tumor sites and present in the bloodstream, are considered to be the precursors of metastases. Considering the key role of CTCs in cancer progression, researchers are committed to analyze them in the past decades and many technologies have been proposed for achieving CTCs isolation and characterization with highly sensitivity and specificity until now. On this basis, clinicians gradually realize the clinical values of CTCs' detection through various clinical studies. As a "liquid biopsy," CTCs' detection and measurement can supply important information for predicting patient's survival, monitoring of response/resistance, assessment of minimal residual disease, evaluating distant metastasis, and sometimes, customizing therapy choices. Nowadays, eliminating CTCs of the blood circulation has been regarded as a promising method to prevent tumor metastasis. However, research on CTCs still faces many challenges. Herein, we present an overview to discuss the current concept of CTCs, summarize the available techniques for CTCs detection, and provide an update on the clinical significance of CTCs in gastrointestinal malignancies, especially focus on gastric and colorectal cancer.

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.

CTCs Expression Profiling for Advanced Breast Cancer Monitoring

The study of circulating tumor cells (CTCs) has a huge clinical interest in advance and metastatic breast cancer patients. However, many approaches are biased by the use of epithelial markers, which underestimate non-epithelial CTCs phenotypes. CTCs enumeration provides valuable prognostic information; however, molecular characterization could be the best option to monitor patients throughout the disease since it may provide more relevant clinical information to the physicians. In this work, we aimed at enumerating and performing a molecular characterization of CTCs from a cohort of 20 patients with metastatic breast cancer (MBC), monitoring the disease at different time points of the therapy, and at progression when it occurred. To this end, we used a CTC negative enrichment protocol that allowed us to recover a higher variety of CTCs phenotypes. With this strategy, we were able to obtain gene expression data from CTCs from all the patients. In addition, we found that high expression levels of PALB2 and MYC were associated with a worse outcome. Interestingly, we identified that CTCs with an EpCAM^highVIM^lowALDH1A1^high signature showed both shorter overall survival (OS) and progression-free survival (PFS), suggesting that CTCs with epithelial-stem features had the most aggressive phenotype.

Analysis of Released Circulating Tumor Cells During Surgery for Non-Small Cell Lung Cancer

PURPOSE

Tumor cells from patients with lung cancer are expelled from the primary tumor into the blood, but difficult to detect in the peripheral circulation. We studied the release of circulating tumor cells (CTCs) during surgery to test the hypothesis that CTC counts are influenced by hemodynamic changes (caused by surgical approach) and manipulation.

EXPERIMENTAL DESIGN

Patients undergoing video-assisted thoracic surgery (VATS) or open surgery for (suspected) primary lung cancer were included. Blood samples were taken before surgery (T0) from the radial artery (RA), from both the RA and pulmonary vein (PV) when the PV was located (T1) and when either the pulmonary artery (T2 open) or the PV (T2 VATS) was dissected. The CTCs were enumerated using the CellSearch system. Single-cell whole-genome sequencing was performed on isolated CTCs for aneuploidy.

RESULTS

CTCs were detected in 58 of 138 samples (42%) of 31 patients. CTCs were more often detected in the PV (70%) compared with the RA (22%, P < 0.01) and in higher counts (P < 0.01). After surgery, the RA but not the PV showed less often CTCs (P = 0.02). Type of surgery did not influence CTC release. Only six of 496 isolated CTCs showed aneuploidy, despite matched primary tumor tissue being aneuploid. Euploid so-called CTCs had a different morphology than aneuploid.

CONCLUSIONS

CTCs defined by CellSearch were identified more often and in higher numbers in the PV compared with the RA, suggesting central clearance. The majority of cells in the PV were normal epithelial cells and outnumbered CTCs. Release of CTCs was not influenced by surgical approach.

Dissection of major cancer gene variants in subsets of circulating tumor cells in advanced breast cancer

Enumeration of circulating tumor cells (CTCs) may reflect the metastatic potential of breast cancer (BC). By using the DEPArray, we investigated CTCs with respect to their epithelial-to-mesenchymal transition phenotype and compared their genomic heterogeneity with tissue biopsies. Seventeen stage IV BC patients were enrolled. Pre-enriched CTC suspensions were stained with fluorescent-labeled antibodies to epithelial (E) and mesenchymal (M) markers. CTC samples were processed by DEPArray system and clustered in relation to their markers. DNA from CTCs, as well as from primary tumor samples, was sequenced by next generation sequencing to assess the mutational state of 50 major cancer-related genes. We identified four different CTC subsets that harbored different gene variants. The most heterogenous CTC subsets included the M+/E− phenotype, which, however, expressed only 7 repeatedly mutated genes, while in the M−/E+ subset multiple mutations affected only 2 out of 50 genes. When matching all gene variants among CTC subsets, a small number of mutations was shared by only 4 genes, namely ATM, FGFR3, PIK3CA, and TP53 that, however, were absent in primary tumors. Our results postulate that the detected mutations in all CTC subsets may be considered as genomic markers of metastatic dissemination to be investigated during early stages of BC.

Whole slide imaging of circulating tumor cells captured on a capillary microchannel device

Liquid biopsy with circulating tumor cells (CTCs) can aid in cancer detection at early stages and determine whether a certain treatment is effective or not. However, existing CTC techniques focus on one or two aspects of CTC management including sampling, enrichment, enumeration, and treatment selection. This paper reports an integrated capillary microchannel device that allows efficient capturing of CTCs with a wide microchannel, rapid enumeration of captured CTCs with whole slide cell imaging, and in situ drug testing with captured CTCs. Blood is drawn into the microchannel whose height is appropriate to the diameter of cancer cells, while its width is a thousand times larger than the diameter of cancer cells. The inner bottom surface of the microchannel is modified with long chain polymers that have cell adhesive ends to efficiently capture CTCs from blood. With this design, cells including CTCs are forced to move through the polymer coated microchannel, and the chance of cell adhesive ends interacting with specific antigens overexpressed on surfaces of cancer cells is significantly enhanced without a channel blockage issue. Captured CTCs are enumerated with a whole slide imaging platform via dual LED autofocusing technology then exposed to anti-cancer drugs, followed by live/dead assay and fluorescence imaging. Given its straightforward, easy and powerless operation, this device with whole slide imaging will be useful for cancer diagnosis, prognosis and point-of-care treatments.

Unravelling tumour heterogeneity by single-cell profiling of circulating tumour cells

Single-cell technologies have contributed to unravelling tumour heterogeneity, now considered a hallmark of cancer and one of the main causes of tumour resistance to cancer therapies. Liquid biopsy (LB), defined as the detection and analysis of cells or cell products released by tumours into the blood, offers an appealing minimally invasive approach that allows the characterization and monitoring of tumour heterogeneity in individual patients. Here, we will review and discuss how circulating tumour cell (CTC) analysis at single-cell resolution provides unique insights into tumour heterogeneity that are not revealed by analysis of circulating tumour DNA (ctDNA) derived from LBs. The molecular analysis of CTCs provides complementary information to that of genomic aberrations determined using ctDNA to fully describe many different cellular components (for example, DNA, RNA, proteins and metabolites) that can influence tumour heterogeneity.

Epithelial keratins: Biology and implications as diagnostic markers for liquid biopsies

Keratins are essential elements of the cytoskeleton of normal and malignant epithelial cells. Because carcinomas commonly maintain their specific keratin expression pattern during malignant transformation, keratins are extensively used as tumor markers in cancer diagnosis including the detection of circulating tumor cells in blood of carcinoma patients. Interestingly, recent biological insights demonstrate that epithelial keratins should not only be considered as mere tumor markers. Emerging evidence suggests an active biological role of keratins in tumor cell dissemination and metastasis. In this review, we illustrate the family of keratin proteins, summarize the latest biological insights into keratin function related to cancer metastasis and discuss the current use of keratins for detection of CTCs and other blood biomarkers used in oncology.

EpCAMlow Circulating Tumor Cells: Gold in the Waste

The CellSearch® system which is still considered the gold standard for the enumeration of circulating tumor cells (CTC) utilizes antibodies against the epithelial cell adhesion molecule (EpCAM) for CTC enrichment. Recently, CTC discarded by the CellSearch® system due to their low EpCAM expression have been isolated and analyzed. We here sought to discuss technical and biological issues concerning the isolation and characterization of EpCAM^low CTC, highlighting the enormous potential of this subpopulation discarded by CellSearch®, which might instead reveal an unexpected clinical significance in tumor types where CTC enumeration has never been validated for prognostic and predictive purpose.

Motivation for Launching a Cancer Metastasis Inhibition (CMI) Program

Metastatic cancers impose significant burdens on patients, affecting quality of life, morbidity, and mortality. Even during remission, microscopic metastases can lurk, but few therapies directly target tumor cell metastasis. Agents that interfere with this process would represent a new paradigm in cancer management, changing the 'waiting game' into a time of active prevention. These therapies could take multiple forms based on the pathways involved in the metastatic process. For example, a phenome-wide association study showed that a single nucleotide polymorphism in the gene TBXA2R is associated with increased metastasis in multiple primary cancers (P = 0.003), suggesting clinical applicability of TBXA2R antagonists. Emerging data related to the role of platelets in metastasis are concordant with our sense that these pathways present significant opportunities for therapeutic development. However, before real progress can be made toward clinical targeting of the metastatic process, foundational work is needed to define informative measures of critical elements such as circulating tumor cells and tumor DNA, and circulatory vs. lymphatic spread. These challenges require an expansion of team science and composition to obtain competitive funding. At our academic medical center, we have implemented a Cancer Metastasis Inhibition (CMI) program investigating this approach across multiple cancers.

Development of a Highly Sensitive Technique for Capturing Renal Cell Cancer Circulating Tumor Cells

Purpose: Liquid biopsy is becoming increasingly important as a guide for selecting new drugs and determining their efficacy. In urological cancer, serum markers for renal cell and urothelial cancers has made the development of liquid biopsy for these cancers strongly desirable. Liquid biopsy is less invasive than conventional tissue biopsy is, enabling frequent biopsies and, therefore, is considered effective for monitoring the treatment course. Circulating tumor cells (CTCs) are a representative liquid biopsy specimen. In the present study, we focused on developing our novel technology for capturing renal cell cancer (RCC)-CTCs using an anti-G250 antibody combined with new devices. Basic experiments of our technology showed that it was possible to detect RCC-CTC with a fairly high accuracy of about 95%. Also, RCC-CTC was identified in the peripheral blood of actual RCC patients. Additionally, during the treatment course of the RCC patient, change in the number of RCC-CTC was confirmed in one case. We believe that the technology we developed will be useful for determining the treatment efficacy and drug selection for the treatment of renal cell cancer (RCC). In order to solve issues such as thresholds setting of this technology, large-scale clinical trials are expected.

Circulating Tumor Cells in Right- and Left-Sided Colorectal Cancer

Molecular alterations are not randomly distributed in colorectal cancer (CRC), but rather clustered on the basis of primary tumor location underlying the importance of colorectal cancer sidedness. We aimed to investigate whether circulating tumor cells (CTC) characterization might help clarify how different the patterns of dissemination might be relative to the behavior of left- (LCC) compared to right-sided (RCC) cancers. We retrospectively analyzed patients with metastatic CRC who had undergone standard baseline CTC evaluation before starting any first-line systemic treatment. Enumeration of CTC in left- and right-sided tumors were compared. The highest prognostic impact was exerted by CTC in left-sided primary cancer patients, even though the lowest median number of cells was detected in this subgroup of patients. CTC exhibit phenotypic heterogeneity, with a predominant mesenchymal phenotype found in CTC from distal compared to proximal primary tumors. Most CTC in RCC patients exhibited an apoptotic pattern. CTC in left-sided colon cancer patients exhibit a predominant mesenchymal phenotype. This might imply a substantial difference in the biology of proximal and distal cancers, associated with different patterns of tumor cells dissemination. The poor prognosis of right-sided CRC is not determined by the hematogenous dissemination of tumor cells, which appears to be predominantly a passive shedding of non-viable cells. Conversely, the subgroup of poor-prognosis left-sided CRC is reliably identified by the presence of mesenchymal CTC.

A flow-through microfluidic system for the detection of circulating melanoma cells

We report the fabrication of polyaniline nanofiber (PANI)-modified screen-printed electrode (PANI/SPE) incorporated in a poly-dimethylsiloxane (PDMS) microfluidic channel for the detection of circulating tumor cells. We employed this device to detect melanoma skin cancer cells through specific immunogenic binding of cell surface biomarker melanocortin 1 receptor (MC1R) to anti-MC1R antibody. The antibody-functionalized PANI/SPE was used in batch-continuous flow-through fashion. An aqueous cell suspension of ferri/ferrocyanide at a flow rate of 1.5 mL/min was passed over the immunosensor, which allowed for continuous electrochemical measurements. The sensor performed exceptionally well affording an ultralow limit of quantification of 1 melanoma cell/mL, both in buffer and when mixed with peripheral blood mononuclear cells, and the response was log-linear over the range of 10-9000 melanoma cells/10 mL.

Circulating Hybrid Cells Join the Fray of Circulating Cellular Biomarkers

Gastrointestinal cancers account for more cancer-related deaths than any other organ system, owing in part to difficulties in early detection, treatment response assessment, and post-treatment surveillance. Circulating biomarkers hold the promise for noninvasive liquid biopsy platforms to overcome these obstacles. Although tumors shed detectable levels of degraded genetic material and cellular debris into peripheral blood, identifying reproducible and clinically relevant information from these analytes (eg, cell-free nucleotides, exosomes, proteins) has proven difficult. Cell-based circulating biomarkers also present challenges, but have multiple advantages including allowing for a more comprehensive tumor analysis, and communicating the risk of metastatic spread. Circulating tumor cells have dominated the cancer cell biomarker field with robust evidence in extraintestinal cancers; however, establishing their clinical utility beyond that of prognostication in colorectal and pancreatic cancers has remained elusive. Recently identified novel populations of tumor-derived cells bring renewed potential to this area of investigation. Cancer-associated macrophage-like cells, immune cells with phagocytosed tumor material, also show utility in prognostication and assessing treatment responsiveness. In addition, circulating hybrid cells are the result of tumor-macrophage fusion, with mounting evidence for a role in the metastatic cascade. Because of their relative abundance in circulation, circulating hybrid cells have great potential as a liquid biomarker for early detection, prognostication, and surveillance. In all, the power of the cell reaches beyond enumeration by providing a cellular source of tumor DNA, RNA, and protein, which can be harnessed to impact overall survival.