Cytokeratin-based CTC counting unrelated to clinical follow up

Targeting circulating tumor cells to prevent metastases

Circulating tumor cells (CTCs) are cancer cells that detach from the primary tumor, enter the bloodstream or body fluids, and spread to other body parts, leading to metastasis. Their presence and characteristics have been linked to cancer progression and poor prognosis in different types of cancer. Analyzing CTCs can offer valuable information about tumors' genetic and molecular diversity, which is crucial for personalized therapy. Epithelial-mesenchymal transition (EMT) and the reverse process, mesenchymal-epithelial transition (MET), play a significant role in generating and disseminating CTCs. Certain proteins, such as EpCAM, vimentin, CD44, and TGM2, are vital in regulating EMT and MET and could be potential targets for therapies to prevent metastasis and serve as detection markers. Several devices, methods, and protocols have been developed for detecting CTCs with various applications. CTCs interact with different components of the tumor microenvironment. The interactions between CTCs and tumor-associated macrophages promote local inflammation and allow the cancer cells to evade the immune system, facilitating their attachment and invasion of distant metastatic sites. Consequently, targeting and eliminating CTCs hold promise in preventing metastasis and improving patient outcomes. Various approaches are being explored to reduce the volume of CTCs. By investigating and discussing targeted therapies, new insights can be gained into their potential effectiveness in inhibiting the spread of CTCs and thereby reducing metastasis. The development of such treatments offers great potential for enhancing patient outcomes and halting disease progression.

Comprehensive optimization of urinary exfoliated tumor cells tests in bladder cancer with a promising microfluidic platform

BACKGROUND

Enrichment of urinary exfoliated tumor cells (UETCs) is a noninvasive way of bladder cancer diagnosis, but the lack of specific capture and identification of tumor cells from the urine remains a limitation that impedes the development of liquid biopsy.

METHODS

The CytoBot^® 2000, a novel circulating cell isolation and enrichment platform, was used for UETCs isolation after comprehensive optimization. The commercial cell lines of bladder cancer were used in spiking assay for cell recovery test. The flow cytometry and immunofluorescent staining assays were performed for expression validation of capture target and identification markers. The performance of optimized platform was validated by 159 clinical samples and analyzed using receiver operator characteristic curve.

RESULTS

The chip that had a pore diameter of 15*20 μm could reduce the background residues while maintaining a higher cell recovery rate. We found that the cell capture ability of chip significantly improved after anti-EpCam antibody encapsulation, but not with T4L6FM1. In identification system optimization, the spiking assay and validation of clinical sample showed that the performance of CK20 and DBC-1 were better that pan-CK in tumor cell identification, in addition, the staining quality is more legible with CK20.

CONCLUSION

The optimized capture chip is more specific for UETCs isolation. CK20 and DBC-1 are both sensitive biomarkers of UETCs in bladder cancer diagnosis. The performance of this optimized platform is excellent in clinical test that improves the accuracy of urine cell testing and provides a new alternative for the clinical application of BLCA liquid biopsy assessment.

Role of Epithelial-to-Mesenchymal Transition for the Generation of Circulating Tumors Cells and Cancer Cell Dissemination

Tumor-related death is primarily caused by metastasis; consequently, understanding, preventing, and treating metastasis is essential to improving clinical outcomes. Metastasis is mainly governed by the dissemination of tumor cells in the systemic circulation: so-called circulating tumor cells (CTCs). CTCs typically arise from epithelial tumor cells that undergo epithelial-to-mesenchymal transition (EMT), resulting in the loss of cell-cell adhesions and polarity, and the reorganization of the cytoskeleton. Various oncogenic factors can induce EMT, among them the transforming growth factor (TGF)-β, as well as Wnt and Notch signaling pathways. This entails the activation of numerous transcription factors, including ZEB, TWIST, and Snail proteins, acting as transcriptional repressors of epithelial markers, such as E-cadherin and inducers of mesenchymal markers such as vimentin. These genetic and phenotypic changes ultimately facilitate cancer cell migration. However, to successfully form distant metastases, CTCs must primarily withstand the hostile environment of circulation. This includes adaption to shear stress, avoiding being trapped by coagulation and surviving attacks of the immune system. Several applications of CTCs, from cancer diagnosis and screening to monitoring and even guided therapy, seek their way into clinical practice. This review describes the process leading to tumor metastasis, from the generation of CTCs in primary tumors to their dissemination into distant organs, as well as the importance of subtyping CTCs to improve personalized and targeted cancer therapy.

Lensless light intensity model for quasi-spherical cell size measurement

Quasi-spherical cell size measurement plays an important role in medical test. Traditional methods such as a microscope and a flow cytometer are either it depends on professionals and cannot be automated, or it is expensive and bulky, which are not suitable for point-of-care test. Lab-on-a-chip technology using the lensless imaging system gives a good solution for obtaining the quasi-spherical cell size. The diffraction effects and the low resolution are the two main problems faced by the lensless imaging system. In this paper, a lensless light intensity model for the quasi-spherical cell size measurement is given. First, the diffraction characteristics of a quasi-spherical cell edge are given. Then, a diffraction model at an arc edge is constructed based on the Fresnel diffraction at a straight edge. Using the diffraction model at an arc edge, we explained the mechanism of the formation of the quasi-spherical cell diffraction fringes. Finally, the light intensity of the first bright ring of the quasi-spherical cell diffraction pattern is used to achieve quasi-spherical cell size measurement. The required equipment and the measurement methods are extremely simple, very suitable for point-of-care test. The experimental results show that the proposed model can realize the statistical measurement of the quasi-spherical cells and the classification of the quasi-spherical cells with a difference of 1 [Formula: see text].

Circulating tumour cells in the -omics era: how far are we from achieving the 'singularity'?

Over the past decade, cancer diagnosis has expanded to include liquid biopsies in addition to tissue biopsies. Liquid biopsies can result in earlier and more accurate diagnosis and more effective monitoring of disease progression than tissue biopsies as samples can be collected frequently. Because of these advantages, liquid biopsies are now used extensively in clinical care. Liquid biopsy samples are analysed for circulating tumour cells (CTCs), cell-free DNA, RNA, proteins and exosomes. CTCs originate from the tumour, play crucial roles in metastasis and carry information on tumour heterogeneity. Multiple single-cell omics approaches allow the characterisation of the molecular makeup of CTCs. It has become evident that CTCs are robust biomarkers for predicting therapy response, clinical development of metastasis and disease progression. This review describes CTC biology, molecular heterogeneity within CTCs and the involvement of EMT in CTC dynamics. In addition, we describe the single-cell multi-omics technologies that have provided insights into the molecular features within therapy-resistant and metastasis-prone CTC populations. Functional studies coupled with integrated multi-omics analyses have the potential to identify therapies that can intervene the functions of CTCs.

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.

Measurement of Circulating Tumor Cells to Track Hepatocellular Carcinoma Progression After Liver Transplantation-Case Report

Management of patients with hepatocellular carcinoma (HCC) largely relies on surgery and other systemic therapies. However, the poor diagnosis of cancer recurrence or metastasis can lead to a high frequency of treatment failure. Thus, factors that can predict disease status and prognosis of patients need to be identified. Circulating tumor cells (CTCs) are known to accurately predict survival of patients. Here, we report a case in which CTCs successfully predicted the progression of metastatic colon polyps after interventional therapy for HCC. A 48-year-old man was diagnosed with HCC with moderate differentiation in 2016 and subsequently underwent orthotopic liver transplantation. Discharge medications were continued with immunosuppressants (tacrolimus) and antiviral drugs (Titin). In 2018, a colon polyp, a type of tubular adenoma, was detected and surgically removed. However, in 2020, the same tubular adenoma recurred. During cancer progression, CTC counts were measured to monitor the status of metastasis, and a positive correlation was noted between the dynamic change in CTC counts and cancer response (metastasis or recurrence). When diagnosing the metastatic adenoma, the number of cytokeratin-positive CTCs was significantly increased; however, it dropped to zero after the polyp was surgically removed. The same change in CTC counts was observed during the second recurrence of the adenoma, and a subgroup of CTCs, cell surface vimentin-positive CTCs, was significantly increased. The CTC count dropped to an undetectable level after the surgery for the first time. In summary, we presented a clinical case in which CTC counts could predict disease progression during HCC metastasis. Thus, CTC counts should be measured after liver transplantation in patients with HCC for diagnosis and clinical decision-making as it is effective in monitoring cancer progression.

Circulating Tumor Cells in Desmoid Tumors: New Perspectives

Introduction

Desmoid tumor (DT) is a rare neoplasm with high local recurrence rates, composed of fibroblastic cells that are characterized by the expression of key molecules, including the intermediate filament vimentin, cyclooxygenase-2 (COX-2), and nuclear β-catenin, and lack of epithelial markers. Circulating tumor cells (CTCs) isolated from the peripheral blood of patients with sarcomas and other neoplasms can be used as early biomarkers of tumor invasion and dissemination. Moreover, CTCs can also re-colonize their tumors of origin through a process of "tumor self-seeding."

Objectives

We aimed to identify CTCs in the peripheral blood of patients with DT and evaluate their expression of β-catenin, transforming growth factor receptor I (TGF-βRI), COX-2, and vimentin proteins.

Material and Methods

We conducted a prospective study of patients with initial diagnosis or relapsed DT with measurable disease. Blood samples from each patient were processed and filtered by ISET^® (Rarecells, France) for CTC isolation and quantification. The CTC expression of β-catenin, COX-2, TGF-βRI, and vimentin was analyzed by immunocytochemistry (ICC).

Results

A total of 18 patients were included, and all had detectable CTCs. We found a concordance of β-catenin expression in both CTCs and primary tumors in 42.8% (6/14) of cases by using ICC and immunohistochemistry, respectively.

Conclusions

Our study identified a high prevalence of CTCs in DT patients. Concordance of β-catenin expression between primary tumor and CTCs brings new perspectives to assess the dynamics of CTCs in the blood compartment, opening new avenues for studying the biology and behavior of DT. In addition, these results open the possibility of using CTCs to predict DT dynamics at the time of disease progression and treatment. Further studies with larger sample sizes are needed to validate our findings.

Circulating Tumor Cell Detection Technologies and Clinical Utility: Challenges and Opportunities

The potential clinical utility of circulating tumor cells (CTCs) in the diagnosis and management of cancer has drawn a lot of attention in the past 10 years. CTCs disseminate from tumors into the bloodstream and are believed to carry vital information about tumor onset, progression, and metastasis. In addition, CTCs reflect different biological aspects of the primary tumor they originate from, mainly in their genetic and protein expression. Moreover, emerging evidence indicates that CTC liquid biopsies can be extended beyond prognostication to pharmacodynamic and predictive biomarkers in cancer patient management. A key challenge in harnessing the clinical potential and utility of CTCs is enumerating and isolating these rare heterogeneous cells from a blood sample while allowing downstream CTC analysis. That being said, there have been serious doubts regarding the potential value of CTCs as clinical biomarkers for cancer due to the low number of promising outcomes in the published results. This review aims to present an overview of the current preclinical CTC detection technologies and the advantages and limitations of each sensing platform, while surveying and analyzing the published evidence of the clinical utility of CTCs.

Liquid Biopsy in Colorectal Carcinoma: Clinical Applications and Challenges

Colorectal carcinoma (CRC) is characterized by wide intratumor heterogeneity with general genomic instability and there is a need for improved diagnostic, prognostic, and therapeutic tools. The liquid biopsy provides a noninvasive route of sample collection for analysis of circulating tumor cells (CTCs) and genomic material, including cell-free DNA (cfDNA), as a complementary biopsy to the solid tumor tissue. The solid biopsy is critical for molecular characterization and diagnosis at the time of collection. The liquid biopsy has the advantage of longitudinal molecular characterization of the disease, which is crucial for precision medicine and patient-oriented treatment. In this review, we provide an overview of CRC and the different methodologies for the detection of CTCs and cfDNA, followed by a discussion on the potential clinical utility of the liquid biopsy in CRC patient care, and lastly, current challenges in the field.

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.

The Prediction Of Epidermal Growth Factor Receptor Mutation And Prognosis Of EGFR Tyrosine Kinase Inhibitor By Serum Ferritin In Advanced NSCLC

Purpose

To investigate the association between level of serum ferritin (SF) and epidermal growth factor receptor (EGFR) mutations and to analyse the impact of SF level on survival times in advanced non-small-cell lung cancer (NSCLC) patients taking EGFR tyrosine kinase inhibitors (EGFR-TKIs).

Methods

A total of 301 patients who were admitted to the Chinese PLA general hospital from August 2015 to August 2017 were enrolled. The association between tumour markers, including SF, CEA, and EGFR mutation, and their impact on the prognosis of patients taking EGFR-TKIs was investigated.

Results

In all patients, the percentage of patients with EGFR mutations was 52.5% (158/301). EGFR mutations were more likely to be detected in younger (<60 years old), adenocarcinoma patients, non-smokers, women, CEA≥5 µg/L and serum ferritin ≥129 µg/L for females or ≥329 µg/L for males (p<0.05). Increased serum ferritin was an independent factor for predicting EGFR mutations (odds ratio (OR)=4.593, 95% CI (2.673–7.890); P <0.001), and an area under curve (AUC) of 0.711 was shown to predict EGFR mutations with a sensitivity of 81.7% and a specificity of 65.2% in women. Sensitivity increased to 91.1% when combining SF and CEA in all patients. SF was also an independent factor (HR=3.531, 95% CI (2.288–5.448); P<0.001) for predicting progression-free survival (PFS) of patients on EGFR-TKIs, analysed by a Cox proportional hazard model, as PFS was shorter in patients with higher SF (15.0 mo. (SF < 129 µg/L for females or <329 for males) vs 10.0 mo. (129–258 µg/L for females or 329–658 µg/L for males) vs 7.3 mo. (>258 µg/L (>258 µg/L for females or >658 µg/L for males) p<0.001).

Conclusion

SF was a significant predictor of EGFR mutation with moderate diagnostic accuracy, and combining SF and CEA increased the diagnostic sensitivity and specificity for EGFR mutations. SF was also useful for predicting survival in EGFR-TKIs.

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

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

Classification of large circulating tumor cells isolated with ultra-high throughput microfluidic Vortex technology

Circulating tumor cells (CTCs) are emerging as rare but clinically significant non-invasive cellular biomarkers for cancer patient prognosis, treatment selection, and treatment monitoring. Current CTC isolation approaches, such as immunoaffinity, filtration, or size-based techniques, are often limited by throughput, purity, large output volumes, or inability to obtain viable cells for downstream analysis. For all technologies, traditional immunofluorescent staining alone has been employed to distinguish and confirm the presence of isolated CTCs among contaminating blood cells, although cells isolated by size may express vastly different phenotypes. Consequently, CTC definitions have been non-trivial, researcher-dependent, and evolving. Here we describe a complete set of objective criteria, leveraging well-established cytomorphological features of malignancy, by which we identify large CTCs. We apply the criteria to CTCs enriched from stage IV lung and breast cancer patient blood samples using the High Throughput Vortex Chip (Vortex HT), an improved microfluidic technology for the label-free, size-based enrichment and concentration of rare cells. We achieve improved capture efficiency (up to 83%), high speed of processing (8 mL/min of 10x diluted blood, or 800 μL/min of whole blood), and high purity (avg. background of 28.8±23.6 white blood cells per mL of whole blood). We show markedly improved performance of CTC capture (84% positive test rate) in comparison to previous Vortex designs and the current FDA-approved gold standard CellSearch assay. The results demonstrate the ability to quickly collect viable and pure populations of abnormal large circulating cells unbiased by molecular characteristics, which helps uncover further heterogeneity in these cells.

Progress and challenges of sequencing and analyzing circulating tumor cells

Circulating tumor cells (CTCs) slough off primary tumor tissues and are swept away by the circulatory system. These CTCs can remain in circulation or colonize new sites, forming metastatic clones in distant organs. Recently, CTC analyses have been successfully used as effective clinical tools to monitor tumor progression and prognosis. With advances in next-generation sequencing (NGS) and single-cell sequencing (SCS) technologies, scientists can obtain the complete genome of a CTC and compare it with corresponding primary and metastatic tumors. CTC sequencing has been successfully applied to monitor genomic variations in metastatic and recurrent tumors, infer tumor evolution during treatment, and examine gene expression as well as the mechanism of the epithelial-mesenchymal transition. However, compared with cancer biopsy sequencing and circulating tumor DNA sequencing, the sequencing of CTC genomes and transcriptomes is more complex and technically difficult. Challenges include enriching pure tumor cells from a background of white blood cells, isolating and collecting cells without damaging or losing DNA and RNA, obtaining unbiased and even whole-genome and transcriptome amplification material, and accurately analyzing CTC sequencing data. Here, we review and summarize recent studies using NGS on CTCs. We mainly focus on CTC genome and transcriptome sequencing and the biological and potential clinical applications of these methodologies. Finally, we discuss challenges and future perspectives of CTC sequencing.

Cellular Expression of PD-L1 in the Peripheral Blood of Lung Cancer Patients is Associated with Worse Survival

Background: Lung cancer treatment has become increasingly dependent upon invasive biopsies to profile tumors for personalized therapy. Recently, tumor expression of programmed death-ligand 1 (PD-L1) has gained interest as a potential predictor of response to immunotherapy. Circulating biomarkers present an opportunity for tumor profiling without the risks of invasive procedures. We characterized PD-L1 expression within populations of nucleated cells in the peripheral blood of lung cancer patients in hopes of expanding the role of liquid biopsy in this setting.Methods: Peripheral blood samples from a multi-institutional prospective study of patients with clinical diagnosis of lung cancer were subjected to cytomorphometric and immunohistochemical evaluation using single-cell, automated slide-based, digital pathology. PD-L1 expression was determined by immunofluorescence.Results: PD-L1 expression was detected within peripheral circulating cells associated with malignancy (CCAM) in 26 of 112 (23%) non-small cell lung cancer patients. Two distinct populations of nucleated, nonhematolymphoid, PD-L1-expressing cells were identified; cytokeratin positive (CK+, PD-L1+, CD45-) and cytokeratin negative (CK-, PD-L1+, CD45-) cells, both with cytomorphometric features (size, nuclear-to-cytoplasm ratio) consistent with tumor cells. Patients with >1.1 PD-L1(+) cell/mL (n = 14/112) experienced worse overall survival than patients with ≤1.1 PD-L1(+) cell/mL (2-year OS: 31.2% vs. 78.8%, P = 0.00159). In a Cox model adjusting for stage, high PD-L1(+) cell burden remained a significant predictor of mortality (HR = 3.85; 95% confidence interval, 1.64-9.09; P = 0.002).Conclusions: PD-L1 expression is detectable in two distinct cell populations in the peripheral blood of lung cancer patients and is associated with worse survival.Impact: These findings could represent a step forward in the development of minimally invasive liquid biopsies for the profiling of tumors. Cancer Epidemiol Biomarkers Prev; 26(7); 1139-45. ©2017 AACR.

FAM172A expression in circulating tumor cells for prediction of high-risk subgroups of colorectal cancer

Objectives

Previous studies used enumerated circulating tumor cells (CTCs) to predict prognosis and therapeutic effect in several types of cancers. However, increasing evidence showed that only enumerated CTCs were not enough to reflect the heterogeneity of tumors. Therefore, we classified different metastasis potentials of CTCs from colorectal cancer (CRC) patients to improve the accuracy of prognosis by CTCs.

Methods

Blood samples were collected from 45 primary CRC patients. CTCs were enriched by blood filtration, and the RNA in situ hybridization method was used to identify and discriminate subgroups of CTCs. Later, FAM172A expression in individual CTCs was measured.

Results

Three CTC subgroups (epithelial/biophenotypic/mesenchymal CTCs) were identified using epithelial–mesenchymal transition markers. In our research, mesenchymal CTCs significantly increased along with tumor progression, including developing distant metastasis and vascular invasion. Furthermore, FAM172A expression rate in mesenchymal CTCs was significantly higher than that in epithelial CTCs, which suggested that FAM172A may correlate with tumor malignancy. This hypothesis was further verified by FAM172A expression in mesenchymal CTCs strictly related to tumor aggressiveness factors. Finally, we revealed that mesenchymal CTCs and FAM172A expression may predict high-risk subgroups in stage II CRC.

Conclusion

Our research proved that CTCs could serve as feasible surrogate samples to detect gene expression as a predictive biomarker for tumor evaluation.

Biophysical isolation and identification of circulating tumor cells

Isolation and enumeration of circulating tumor cells (CTCs) from blood is important for determining patient prognosis and monitoring treatment. Methods based on affinity to cell surface markers have been applied to both purify (via immunoseparation) and identify (via immunofluorescence) CTCs. However, variability of cell biomarker expression associated with tumor heterogeneity and evolution and cross-reactivity of antibody probes have long complicated CTC enrichment and immunostaining. Here, we report a truly label-free high-throughput microfluidic approach to isolate, enumerate, and characterize the biophysical properties of CTCs using an integrated microfluidic device. Vortex-mediated deformability cytometry (VDC) consists of an initial vortex region which enriches large CTCs, followed by release into a downstream hydrodynamic stretching region which deforms the cells. Visualization and quantification of cell deformation with a high-speed camera revealed populations of large (>15 μm diameter) and deformable (aspect ratio >1.2) CTCs from 16 stage IV lung cancer samples, that are clearly distinguished by increased deformability compared to contaminating blood cells and rare large cells isolated from healthy patients. The VDC technology demonstrated a comparable positive detection rate of putative CTCs above healthy baseline (93.8%) with respect to standard immunofluorescence (71.4%). Automation allows full enumeration of CTCs from a 10 mL vial of blood within <1 h after sample acquisition, compared with 4+ hours with standard approaches. Moreover, cells are released into any collection vessel for further downstream analysis. VDC shows potential for accurate CTC enumeration without labels and confirms the unique highly deformable biophysical properties of large CTCs circulating in blood.

Prognostic value of circulating tumor cells in the peripheral blood of patients with esophageal squamous cell carcinoma

OBJECTIVE

Circulating tumor cells (CTCs) of patients with malignant tumors can be used as a prognostic marker. However, there are few relevant reports to date on esophageal squamous cell carcinoma (ESCC). Our study assesses the clinical significance of CTCs in ESCC patients.

PATIENTS AND METHODS

CTCs were detected in 103 peripheral blood (PB) samples from 59 ESCC patients. Correlation between CTCs and clinical parameters was analyzed using the χ² test or Fisher's exact test. Overall survival (OS) and progression-free survival (PFS) were analyzed using Kaplan-Meier analysis and univariate and multivariate methods.

RESULTS

The CTC detection rate was 79.7% (47/59) at baseline. The frequency of CTC-positive patients increased as the disease stage advanced (88.0% in stages III-IV, 58.9% in stages I-II). CTC counts ≥0/7.5 mL of PB were correlated with the degree of tumor differentiation, tumor infiltration, and lymph node and distant metastases. Overall, the OS and PFS of patients with CTC counts ≥3 or ≥5/7.5 mL of PB before surgery were significantly shorter than those of patients with CTC counts <3 or <5/7.5 mL. Multivariate analysis showed CTC counts ≥5/7.5 mL of PB to be a strong prognostic indicator of OS (hazard ratio [HR] 12.478; 95% confidence interval [CI], 8.2-34.3; P<0.05) and PFS (HR 6.524; 95% CI, 1.2-34.3; P<0.05) in ESCC patients. Patients in whom CTCs changed from positive at baseline to a negative value after surgery had an excellent prognosis.

CONCLUSION

CTCs might serve as a reference indicator for the prognosis and monitoring of disease progression and treatment effects in ESCC.

Circulating Tumor Cells: Fluid Surrogates of Solid Tumors

Evaluation of circulating tumor cells (CTCs) has demonstrated clinical validity as a prognostic tool based on enumeration, but since the introduction of this tool to the clinic in 2004, further clinical utility and widespread adoption have been limited. However, immense efforts have been undertaken to further the understanding of the mechanisms behind the biology and kinetics of these rare cells, and progress continues toward better applicability in the clinic. This review describes recent advances within the field, with a particular focus on understanding the biological significance of CTCs, and summarizes emerging methods for identifying, isolating, and interrogating the cells that may provide technical advantages allowing for the discovery of more specific clinical applications. Included is an atlas of high-definition images of CTCs from various cancer types, including uncommon CTCs captured only by broadly inclusive nonenrichment techniques.

Technical Insights into Highly Sensitive Isolation and Molecular Characterization of Fixed and Live Circulating Tumor Cells for Early Detection of Tumor Invasion

Circulating Tumor Cells (CTC) and Circulating Tumor Microemboli (CTM) are Circulating Rare Cells (CRC) which herald tumor invasion and are expected to provide an opportunity to improve the management of cancer patients. An unsolved technical issue in the CTC field is how to obtain highly sensitive and unbiased collection of these fragile and heterogeneous cells, in both live and fixed form, for their molecular study when they are extremely rare, particularly at the beginning of the invasion process. We report on a new protocol to enrich from blood live CTC using ISET^® (Isolation by SizE of Tumor/Trophoblastic Cells), an open system originally developed for marker-independent isolation of fixed tumor cells. We have assessed the impact of our new enrichment method on live tumor cells antigen expression, cytoskeleton structure, cell viability and ability to expand in culture. We have also explored the ISET^®in vitro performance to collect intact fixed and live cancer cells by using spiking analyses with extremely low number of fluorescent cultured cells. We describe results consistently showing the feasibility of isolating fixed and live tumor cells with a Lower Limit of Detection (LLOD) of one cancer cell per 10 mL of blood and a sensitivity at LLOD ranging from 83 to 100%. This very high sensitivity threshold can be maintained when plasma is collected before tumor cells isolation. Finally, we have performed a comparative next generation sequencing (NGS) analysis of tumor cells before and after isolation from blood and culture. We established the feasibility of NGS analysis of single live and fixed tumor cells enriched from blood by our system. This study provides new protocols for detection and characterization of CTC collected from blood at the very early steps of tumor invasion.

Reality of Single Circulating Tumor Cell Sequencing for Molecular Diagnostics in Pancreatic Cancer

To understand the potential and limitations of circulating tumor cell (CTC) sequencing for molecular diagnostics, we investigated the feasibility of identifying the ubiquitous KRAS mutation in single CTCs from pancreatic cancer (PC) patients. We used the NanoVelcro/laser capture microdissection CTC platform, combined with whole genome amplification and KRAS Sanger sequencing. We assessed both KRAS codon-12 coverage and the degree that allele dropout during whole genome amplification affected the detection of KRAS mutations from single CTCs. We isolated 385 single cells, 163 from PC cell lines and 222 from the blood of 12 PC patients, and obtained KRAS sequence coverage in 218 of 385 single cells (56.6%). For PC cell lines with known KRAS mutations, single mutations were detected in 67% of homozygous cells but only 37.4% of heterozygous single cells, demonstrating that both coverage and allele dropout are important causes of mutation detection failure from single cells. We could detect KRAS mutations in CTCs from 11 of 12 patients (92%) and 33 of 119 single CTCs sequenced, resulting in a KRAS mutation detection rate of 27.7%. Importantly, KRAS mutations were never found in the 103 white blood cells sequenced. Sequencing of groups of cells containing between 1 and 100 cells determined that at least 10 CTCs are likely required to reliably assess KRAS mutation status from CTCs.

The Role of CTCs as Tumor Biomarkers

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

Circulating tumor cell technologies†

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

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

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

We highlight the key features of individual technologies.

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

Circulating tumor cell isolation: the assets of filtration methods with polycarbonate track-etched filters

Circulating tumor cells (CTCs) arise from primary or secondary tumors and enter the bloodstream by active or passive intravasation. Given the low number of CTCs, enrichment is necessary for detection. Filtration methods are based on selection of CTCs by size using a filter with 6.5 to 8 µm pores. After coloration, collected CTCs are evaluated according to morphological criteria. Immunophenotyping and fluorescence in situ hybridization techniques may be used. Selected CTCs can also be cultivated in vitro to provide more material. Analysis of genomic mutations is difficult because it requires adapted techniques due to limited DNA materials. Filtration-selected CTCs have shown prognostic value in many studies but multicentric validating trials are mandatory to strengthen this assessment. Other clinical applications are promising such as follow-up, therapy response prediction and diagnosis. Microfluidic emerging systems could optimize filtration-selected CTCs by increasing selection accuracy.

Detection of KRAS mutations in circulating tumor cells from patients with metastatic colorectal cancer

BACKGROUND

Quantification of Circulating Tumor Cells (CTCs) as a prognostic marker in metastatic colorectal cancer (mCRC) has already been validated and approved for routine use. However, more than quantification, qualification or characterization of CTCs is gaining importance, since the genetic characterization of CTCs may reflect, in a real time fashion, genetic profile of the disease.

OBJECTIVE

To characterize KRAS mutations (codon 12 and 13) in CTCs from patients with mCRC and to compare with matched primary tumor. Additionally, correlate these mutations with clinical and pathological features of patients.

METHODS

Blood samples were collected from 26 patients with mCRC from the AC Camargo Cancer Center (São Paulo-Brazil). CTCs were isolated by ISET technology (Isolation by Size of Epithelial Tumors; Rarecells Diagnostics, France) and mutations analyzes were performed by pyrosequencing (QIAGEN).

RESULTS

KRAS mutation was detected in 7 of the 21 cases (33%) of samples from CTCs. In matched primary tumors, 9 of the 24 cases (37.5%) were found KRAS mutated. We observed that 5 of the 9 samples with KRAS mutation in their primary tumor had also KRAS mutation in CTCs, meaning a concordance of 71% of matched cases (P = 0.017). KRAS mutation neither on primary tumor nor in CTCs was associated with clinical-pathological parameters analyzed.

CONCLUSION

Faced with a polyclonal disease like colorectal cancer, which is often treated with alternating and successive lines of chemotherapy, real time genetic characterization of CTCs, in a fast and feasible fashion, can provide important information to clinical management of metastatic patients. Although our cohort was limited, it was possible to show a high grade of concordance between primary tumor and CTCs, which suggests that CTCs can be used as surrogate of primary tumors in clinical practice, when the knowledge of mutation profile is necessary and the primary tumor is not available.

Analytical Validation and Capabilities of the Epic CTC Platform: Enrichment-Free Circulating Tumour Cell Detection and Characterization

The Epic Platform was developed for the unbiased detection and molecular characterization of circulating tumour cells (CTCs). Here, we report assay performance data, including accuracy, linearity, specificity and intra/inter-assay precision of CTC enumeration in healthy donor (HD) blood samples spiked with varying concentrations of cancer cell line controls (CLCs). Additionally, we demonstrate clinical feasibility for CTC detection in a small cohort of metastatic castrate-resistant prostate cancer (mCRPC) patients. The Epic Platform demonstrated accuracy, linearity and sensitivity for the enumeration of all CLC concentrations tested. Furthermore, we established the precision between multiple operators and slide staining batches and assay specificity showing zero CTCs detected in 18 healthy donor samples. In a clinical feasibility study, at least one traditional CTC/mL (CK+, CD45-, and intact nuclei) was detected in 89 % of 44 mCRPC samples, whereas 100 % of samples had CTCs enumerated if additional CTC subpopulations (CK-/CD45- and CK+ apoptotic CTCs) were included in the analysis. In addition to presenting Epic Platform's performance with respect to CTC enumeration, we provide examples of its integrated downstream capabilities, including protein biomarker expression and downstream genomic analyses at single cell resolution.

Thymidylate synthase expression in circulating tumor cells: a new tool to predict 5-fluorouracil resistance in metastatic colorectal cancer patients

Thymidylate synthase (TYMS) is an important enzyme for 5‐fluorouracil (5‐FU) metabolism in metastatic colorectal cancer (mCRC) patients. The search for this enzyme in circulating tumor cells (CTCs) can be a powerful tool to follow‐up cancer patients. mCRC patients were enrolled before the beginning of 5‐FU‐based chemotherapy. The blood was filtered on Isolation by Size of Epithelial Tumor Cells (ISET), and the analysis of TYMS expression in CTCs was made by immunocytochemistry. Additionally, we verified TYMS staining in primary tumors and metastases from the same patients. There were included 54 mCRC patients and 47 of them received 5‐FU‐based chemotherapy. The median CTCs number was 2 per mL. We were not able to analyze immunocytochemistry in 13 samples (9 patients with absence of CTCs and 4 samples due to technical reasons). Therefore, TYMS expression on CTCs was analyzed in 34 samples and was found positive in 9 (26.5%). Six of these patients had tumor progression after treatment with 5‐FU. We found an association between CTC TYMS staining and disease progression (DP), although without statistical significance (P = 0.07). TYMS staining in primary tumors and metastases tissues did not have any correlation with disease progression (P = 0.67 and P = 0.42 respectively). Patients who had CTC count above the median (2 CTCs/mL) showed more TYMS expression (P = 0.02) correlating with worse prognosis. Our results searching for TYMS staining in CTCs, primary tumors and metastases suggest that the analysis of TYMS can be useful tool as a 5‐FU resistance predictor biomarker if analyzed in CTCs from mCRC patients.

What's new?

Currently, the common treatment strategy for metastatic colorectal cancer patients is 5‐Fluorouracil‐based chemotherapy, which shows high efficacy in a subset of patients. Even those patients, however, can experience disease progression due to 5‐FU resistance. There are indications that the DNA replication and repair enzyme thymidylate synthase (TYMS) may be involved. Here, the authors set to measure circulating tumor cells levels and search for TYMS staining to correlate these findings with clinical outcome. The results suggest that circulating tumor cells represent a powerful tool to follow up 5‐FU resistance in metastatic colorectal cancer patients in real time, by TYMS expression analysis.

Circulating Tumor Cells: Who is the Killer?

This article is a critical note on the subject of Circulating Tumor Cells (CTC). It takes into account the tumor identity of Circulating Tumor Cells as cancer seeds in transit from primary to secondary soils, rather than as a “biomarker”, and considers the help this field could bring to cancer patients. It is not meant to duplicate information already available in a large number of reviews, but to stimulate considerations, further studies and development helping the clinical use of tumor cells isolated from blood as a modern personalized, non-invasive, predictive test to improve cancer patients’ life. The analysis of CTC challenges, methodological bias and critical issues points out to the need of referring to tumor cells extracted from blood without any bias and identified by cytopathological diagnosis as Circulating Cancer Cells (CCC). Finally, this article highlights recent developments and identifies burning questions which should be addressed to improve our understanding of the domain of CCC and their potential to change the clinical practice.

Isolation, detection, and immunomorphological characterization of circulating tumor cells (CTCs) from patients with different types of sarcoma using isolation by size of tumor cells: a window on sarcoma-cell invasion

Background

Sarcomas are rare and heterogeneous neoplasms with poor prognosis that are thought to spread to distant organs mainly by hematogenous dissemination. However, circulating tumor cells (CTCs) have never been visualized in sarcomas.

Objectives

To investigate the feasibility of using isolation by size of tumor cells (ISET) for isolation, identification, and characterization of CTCs derived from patients with high-grade and metastatic sarcomas.

Patients and methods

We studied eleven patients with metastatic/recurrent or locally advanced soft-tissue sarcomas (STSs), six of whom had synovial sarcomas. Blood samples (8 mL) were collected from patients with advanced STS and treated by ISET, a marker- independent approach that isolates intact CTCs from blood, based on their larger size compared with leukocytes. CTCs were identified by cytomorphology and characterized by dual-color immunocytochemistry using antivimentin or anti-Pan CK, and anti-CD45.

Results

All patients with STS included in this study showed CTCs, with numbers ranging from two to 48 per 8 mL of blood.

Conclusion

This study shows the feasibility of isolating, identifying, and characterizing CTCs from patients with different types of sarcomas and the presence of circulating sarcoma cells in all the tested patients. Our results set the basis for further studies aimed at exploring the presence, number, and immunomolecular characteristics of CTCs in different types of sarcoma, and bring more light to the mechanisms of tumor invasion for these tumors.