Circulating tumor cells as a window on metastasis biology in lung cancer

Detection of Driver and Resistance Mutations in Leptomeningeal Metastases of NSCLC by Next-Generation Sequencing of Cerebrospinal Fluid Circulating Tumor Cells

Purpose: Leptomeningeal metastases are more common in non-small cell lung cancer (NSCLC) with EGFR mutations. The diagnosis is difficult by traditional imaging only, and leads to poor understanding of resistance mechanisms of leptomeningeal metastases.Experimental Design: We compared the CellSearch Assay, the Thinprep cytologic test (TCT), and brain magnetic resonance imaging (MRI) in 21 NSCLC patients with suspected leptomeningeal metastases. Next-generation sequencing that included 416 cancer-associated genes was also performed on cerebrospinal fluid circulating tumor cells (CSFCTC) of 19 patients.Results: Twenty-one patients were diagnosed with leptomeningeal metastases, and CSFCTCs were captured by CellSearch in 20 patients (median, 969 CSFCTCs/7.5 mL; range, 27-14,888). CellSearch had a sensitivity of 95.2% for leptomeningeal metastases diagnosis, which was higher than that of TCT (12/21, 57.1%), MRI (10/21, 47.6%), and MRI plus TCT (19/21, 90.5%), respectively. CTCs were found only in 5 of 14 patients (median, 2 CTCs/7.5 mL; range, 2-4), which was a much lower ratio than CSFCTCs. Genetic profiles of CSFCTCs were highly concordant with molecular mutations identified in the primary tumor (17/19, 89.5%). The resistance gene EGFR T790M was detected in 7 of 9 patients with extracranial lesions, but was detected in only 1 of 14 CSFCTC samples. Other potential resistant mutations, such as MET amplification and ERBB2 mutation, were also identified in CSFCTCs.Conclusions: CSFCTCs captured by CellSearch may be a more sensitive and effective way to diagnose leptomeningeal metastases, and may serve as a liquid biopsy medium for gene profiles in NSCLC patients with leptomeningeal metastases. Clin Cancer Res; 23(18); 5480-8. ©2017 AACR.

The Potential for Circulating Tumor Cells in Pancreatic Cancer Management

Pancreatic cancer is one the most lethal malignancies. Only a small proportion of patients with this disease benefit from surgery. Chemotherapy provides only a transient benefit. Though much effort has gone into finding new ways for early diagnosis and treatment, average patient survival has only been improved in the order of months. Circulating tumor cells (CTCs) are shed from primary tumors, including pre-malignant phases. These cells possess information about the genomic characteristics of their tumor source in situ, and their detection and characterization holds potential in early cancer diagnosis, prognosis, and treatment. Liquid Biopsies present an alternative to tumor biopsy that are hard to sample. Below we summarize current methods of CTC detection, the current literature on CTCs in pancreatic cancer, and future perspectives.

Epithelial-mesenchymal plasticity and circulating tumor cells: Travel companions to metastases

Epithelial-mesenchymal transitions (EMTs) associated with metastatic progression may contribute to the generation of hybrid phenotypes capable of plasticity. This cellular plasticity would provide tumor cells with an increased potential to adapt to the different microenvironments encountered during metastatic spread. Understanding how EMT may functionally equip circulating tumor cells (CTCs) with an enhanced competence to survive in the bloodstream and niche in the colonized organs has thus become a major cancer research axis. We summarize here clinical data with CTC endpoints involving EMT. We then review the work functionally linking EMT programs to CTC biology and deciphering molecular EMT-driven mechanisms supporting their metastatic competence. Developmental Dynamics 247:432-450, 2018. © 2017 Wiley Periodicals, Inc.

Detection of Circulating Tumor Cells and Circulating Tumor Microemboli in Gastric Cancer

PURPOSE: Gastric cancer studies indicated a potential correlation between circulating tumor cells (CTCs) in peripheral blood and tumor relapse/metastasis. The prevalence and significance of circulating tumor microemboli (CTM) in gastric cancer remain unknown. We investigated the prevalence and prognostic value of CTCs and CTM for progression-free survival (PFS) and overall survival (OS) in gastric cancer patients. METHODS:Eighty-one gastric cancer patients consented to provide 5 ml of peripheral blood before systematic therapy. CTCs and CTM were isolated using isolation by size of epithelial tumor cells and characterized by cytopathologists. For 41 stage IV gastric cancer patients, CTM was investigated as a potential biomarker to predict prognosis. RESULTS:CTCs were detected in 51 patients; the average count was 1.81. In clinical stage I, II, III, and IV patients, the average CTC counts were 1.40, 0.67, 1.24, and 2.71, respectively. CTM were detected in 3 of 33 clinical stage I to IIIb patients, at an average of 0.12 (0-2). CTM were detected in 13 of 53 clinical stage IIIc to IV patients, at an average of 1.26 (0-22). In stage IV patients, CTM positivity correlated with the CA125 level. PFS and OS in CTM-positive patients were significantly lower than in CTM-negative patients (P < .001). CTM positivity was an independent factor for determining the PFS (P = .016) and OS (P = .003) of stage IV patients in multivariate analysis. Using markers of the epithelial-mesenchymal transition, single CTCs were divided into three phenotypes including epithelial CTCs, biphenotypic epithelial/mesenchymal CTCs, and mesenchymal CTCs. For CTM, CK−/Vimentin+/CD45− and CK+/Vimentin+/CD45− phenotypes were observed, but the CK+/Vimentin−/CD45− CTM phenotype was not. CA125 was detected in gastric cancer cell lines BGC823 and MGC803. CONCLUSIONS: In stage IV patients, CTM positivity was correlated with serum CA125 level. CTM were an independent predictor of shorter PFS and OS in stage IV patients. Thus, CTM detection may be a useful tool to predict prognosis in stage IV patients.

TTF-1- and/or CD56-positive Circulating Tumor Cells in patients with small cell lung cancer (SCLC)

The aim of the study was to evaluate the phenotypic CTCs heterogeneity (TTF-1⁺ and/or CD56⁺) in SCLC patients and correlate it with the CellSearch. Peripheral blood was obtained from 108 consecutive patients. CTCs were detected by CellSearch and double-immunofluorescence using anti-CD45, anti-TTF-1 and anti-CD56 antibodies. Before chemotherapy TTF-1⁺/CD45⁻, CD56⁺/CD45⁻ and TTF-1⁺/CD56⁺ CTCs were detected in 66(61.1%), 55(50.9%) and 46(42.6%) patients, respectively; 60.2% of patients were CellSearch⁺. Among the 22 patients with 0 CTCs/7.5 ml on CellSearch, TTF-1⁺/CD45⁻, CD56⁺/CD45⁻ and TTF-1⁺/CD56⁺ CTCs were detected in 8(36.4%), 6(27.3) and 6(27.3%) patients, respectively; no CK⁺/EpCAM⁺ or TTF1⁺/EpCAM⁺ CTCs were detected in these patients. One-chemotherapy cycle decreased both the number of positive patients (p < 0.001) and their CTC number (p < 0.001), irrespectively of their phenotype and the detection method. The incidence and number of the different CTC subpopulations on PD, was significantly increased at their baseline levels. Multivariate analysis revealed that the increased number of CTCs at baseline and on PD were significantly associated with decreased PFS (p = 0.048) and OS (p = 0.041), respectively. There is an important CTC heterogeneity in such patients according to the expression of TTF-1 and CD56 which could detect EpCAM⁻ CTC subpopulations and, thus, undetectable by CellSearch. These CTC subpopulations are dynamically correlated with treatment efficacy and disease-progression.

[Diagnostic Value of Folate Receptor-positive Circulating Tumor Cell in Lung Cancer: A Pilot Study]

背景与目的

评价一种通过叶酸受体(folate receptor, FR)检测循环肿瘤细胞(circulating tumor cell, CTC)的方法用于肺癌临床诊断的实用性和可行性及进一步探究CTC在肺癌术后复发的预测价值。

方法

通过免疫磁珠负向富集方法从3 mL外周血中捕获循环肿瘤细胞，再用肿瘤特异性叶酸配体-寡核苷酸偶和物标记捕获的循环肿瘤细胞，洗去没有结合的偶和物后，洗脱下特异性结合的偶合物的寡核苷酸用于定量PCR扩增分析。

结果

97例肺癌患者的CTC水平高于肺部良性疾病患者(P < 0.001)。本检测方法以8.7 Folate Units/3 mL为cutoff值，结果显示靶向PCR法对肺癌的检测灵敏度为82.5%，特异性为72.2%，特别是在Ⅰ期肺癌灵敏度达到86.8%。与其他肿瘤标志物(NSE、CEA、CYFRA21-1)比较，CTC对肺癌及Ⅰ期肺癌具有较高的诊断准确性(0.859; 95%CI: 0.779-0.939)和(0.912; 95%CI: 0.829-0.994)。5例肺癌患者术后2周内CTC水平高于cutoff值。

结论

叶酸受体阳性循环肿瘤细胞可以应用于肺癌的临床诊断，即使是对早期非小细胞肺癌(non-small cell lung cancer, NSCLC)的诊断。

Detection of Circulating Tumor Cells Using Negative Enrichment Immunofluorescence and an In Situ Hybridization System in Pancreatic Cancer

Pancreatic cancer (PC) is the most lethal type of gastrointestinal cancer, and early detection and monitoring is an urgent problem. Circulating tumor cells (CTCs) are emerging as a non-invasive biomarker for tumor detection. However, the low sensitivity is a main problem in the traditional CellSearch System for detecting CTCs, especially in patients with PC. In this study, we used negative enrichment (NE), immunofluorescence and in situ hybridization (FISH) of chromosome 8 (NE-iFISH) to capture and identify CTCs in PC patients. We showed that the NE-iFISH system exhibited a dramatically high detection rate of CTCs in PC patients (90%). The diagnostic rate of PC reached 97.5% when combining CTCs ≥ 2 and carbohydrate antigen 19-9 (CA19-9) > 37 µmol/L. The 1-year survival in the group of CTCs < 3 was significantly higher than that of CTCs ≥ 3 (p = 0.043). In addition, we analyzed the role of chromosomal instability in CTCs detection. The group of triploid (three hybridization signals of chromosome 8) CTCs ≥ 3 showed a shorter 1-year survival (p = 0.0279) and overall survival (p = 0.0188) than the group with triploid CTCs < 3. Importantly, the triploid CTC number but not the overall CTC counts could be a predictor of chemo-sensitivity. Moreover, circulating tumor microembolus (CTMs) were found in stage IV patients, and were positively related to the poor response to chemotherapy. In conclusion, the NE-iFISH system significantly improved the positive detection rate of CTCs and triploid CTC could be used to predict prognosis or the response to the chemotherapy of PC patients. CTM is a potential indicator of the chemotherapeutic effect in advanced PC patients.

Phenotypic plasticity in prostate cancer: role of intrinsically disordered proteins

A striking characteristic of cancer cells is their remarkable phenotypic plasticity, which is the ability to switch states or phenotypes in response to environmental fluctuations. Phenotypic changes such as a partial or complete epithelial to mesenchymal transition (EMT) that play important roles in their survival and proliferation, and development of resistance to therapeutic treatments, are widely believed to arise due to somatic mutations in the genome. However, there is a growing concern that such a deterministic view is not entirely consistent with multiple lines of evidence, which indicate that stochasticity may also play an important role in driving phenotypic plasticity. Here, we discuss how stochasticity in protein interaction networks (PINs) may play a key role in determining phenotypic plasticity in prostate cancer (PCa). Specifically, we point out that the key players driving transitions among different phenotypes (epithelial, mesenchymal, and hybrid epithelial/mesenchymal), including ZEB1, SNAI1, OVOL1, and OVOL2, are intrinsically disordered proteins (IDPs) and discuss how plasticity at the molecular level may contribute to stochasticity in phenotypic switching by rewiring PINs. We conclude by suggesting that targeting IDPs implicated in EMT in PCa may be a new strategy to gain additional insights and develop novel treatments for this disease, which is the most common form of cancer in adult men.

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.

Cytokeratin-14 contributes to collective invasion of salivary adenoid cystic carcinoma

Collective invasion of cells plays a fundamental role in tissue growth, wound healing, immune response and cancer metastasis. This paper aimed to investigate cytokeratin-14 (CK14) expression and analyze its association with collective invasion in the invasive front of salivary adenoid cystic carcinoma (SACC) to uncover the role of collective invasion in SACC. Here, in the clinical data of 121 patients with SACC, the positive expression of CK14 was observed in 35/121(28.93%) of the invasive front of SACC. CK14 expression in the invasive front, local regional recurrence and distant metastasis were independent and significant prognostic factors in SACC patients. Then, we found that in an ex vivo 3D culture assay, CK14 siRNA receded the collective invasion, and in 2D monolayer culture, CK14 overexpression induced a collective SACC cell migration. These data indicated that the presence of characterized CK14+ cells in the invasive front of SACC promoted collective cell invasion of SACC and may be a biomarker of SACC with a worse prognosis.

Circulating tumor cells are associated with bone metastasis of lung cancer

Lung cancer (LC) is the leading cause of cancer mortality worldwide, predominantly due to the difficulty of early diagnosis and its high metastatic potential. Recently, increasing evidence suggests that circulating tumour cells (CTCs) are responsible for cancer metastatic relapse, and CTCs have attracted interest in cancer metastasis detection and quantification. In present study, we collected blood samples from 67 patients with bone metastasis, and 30 patients without such metastasis, and searched for CTCs. Then the association of CTC numbers with bone metastasis and other clinico-pothological variants was analyzed. Results demonstrated that when 5 or 1 was taken as a threshhold for the CTC number, there were significantly higher positivity of CTCs in the bone metastasis group than in the non-metastasis group. While the increase in CTC number was not significantly associated with any other clinicopathological factor, including age, gender, pathological type, intrapulmonary metastasis and lymph node metastasis, the CTC number in patients with positivity of the last above mentioned variants was obviously higher than in patients with negativity of the two variants. Taken together, the CTC number appears to be significantly associated with the bone metastasis from lung cancer.

Thrombin-unique coagulation system protein with multifaceted impacts on cancer and metastasis

The association between blood coagulation and cancer development is well recognized. Thrombin, the pleiotropic enzyme best known for its contribution to fibrin formation and platelet aggregation during vascular hemostasis, may also trigger cellular events through protease-activated receptors, PAR-1 and PAR-4, leading to cancer progression. Our pioneering findings provided evidence that thrombin contributes to cancer metastasis by increasing adhesive potential of malignant cells. However, there is evidence that thrombin regulates every step of cancer dissemination: (1) cancer cell invasion, detachment from primary tumor, migration; (2) entering the blood vessel; (3) surviving in vasculature; (4) extravasation; (5) implantation in host organs. Recent studies have provided new molecular data about thrombin generation in cancer patients and the mechanisms by which thrombin contributes to transendothelial migration, platelet/tumor cell interactions, angiogenesis, and other processes. Though a great deal is known regarding the role of thrombin in cancer dissemination, there are new data for multiple thrombin-mediated events that justify devoting focus to this topic with a comprehensive approach.

The liquid biopsy in lung cancer

The incidence of lung cancer has significantly increased over the last century, largely due to smoking, and remains the most common cause of cancer deaths worldwide. This is often due to lung cancer first presenting at late stages and a lack of curative therapeutic options at these later stages. Delayed diagnoses, inadequate tumor sampling, and lung cancer misdiagnoses are also not uncommon due to the limitations of the tissue biopsy. Our better understanding of the tumor microenvironment and the systemic actions of tumors, combined with the recent advent of the liquid biopsy, may allow molecular diagnostics to be done on circulating tumor markers, particularly circulating tumor DNA. Multiple liquid biopsy molecular methods are presently being examined to determine their efficacy as surrogates to the tumor tissue biopsy. This review will focus on new liquid biopsy technologies and how they may assist in lung cancer detection, diagnosis, and treatment.

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.

Fourier Ptychographic Microscopy for Rapid, High-Resolution Imaging of Circulating Tumor Cells Enriched by Microfiltration

Examining the hematogenous compartment for evidence of metastasis has increased significantly within the oncology research community in recent years, due to the development of technologies aimed at the enrichment of circulating tumor cells (CTCs), the subpopulation of primary tumor cells that gain access to the circulatory system and are responsible for colonization at distant sites. In contrast to other technologies, filtration-based CTC enrichment, which exploits differences in size between larger tumor cells and surrounding smaller, non-tumor blood cells, has the potential to improve CTC characterization through isolation of tumor cell populations with greater molecular heterogeneity. However, microscopic analysis of uneven filtration surfaces containing CTCs is laborious, time-consuming, and inconsistent, preventing widespread use of filtration-based enrichment technologies. Here, integrated with a microfiltration-based CTC and rare cell enrichment device we have previously described, we present a protocol for Fourier Ptychographic Microscopy (FPM), a method that, unlike many automated imaging platforms, produces high-speed, high-resolution images that can be digitally refocused, allowing users to observe objects of interest present on multiple focal planes within the same image frame. The development of a cost-effective and high-throughput CTC analysis system for filtration-based enrichment technologies could have profound clinical implications for improved CTC detection and analysis.

Liquid Biopsy in Non-Small Cell Lung Cancer

Liquid biopsy analyses are already incorporated in the routine clinical practice in many hospitals and oncology departments worldwide, improving the selection of treatments and monitoring of lung cancer patients. Although they have not yet reached its full potential, liquid biopsy-based tests will soon be as widespread as “standard” biopsies and imaging techniques, offering invaluable diagnostic, prognostic, and predictive information. This review summarizes the techniques available for the isolation and analysis of circulating free DNA and RNA, exosomes, tumor-educated platelets, and circulating tumor cells from the blood of cancer patients, presents the methodological challenges associated with each of these materials, and discusses the clinical applications of liquid biopsy testing in lung cancer.

Modes of invasion during tumour dissemination

Cancer cell migration and invasion underlie metastatic dissemination, one of the major problems in cancer. Tumour cells exhibit a striking variety of invasion strategies. Importantly, cancer cells can switch between invasion modes in order to cope with challenging environments. This ability to switch migratory modes or plasticity highlights the challenges behind antimetastasis therapy design. In this Review, we present current knowledge on different tumour invasion strategies, the determinants controlling plasticity and arising therapeutic opportunities. We propose that targeting master regulators controlling plasticity is needed to hinder tumour dissemination and metastasis.

Inertia based microfluidic capture and characterisation of circulating tumour cells for the diagnosis of lung cancer

BACKGROUND

Routine clinical application of circulating tumour cells (CTCs) for blood based diagnostics is yet to be established. Despite growing evidence of their clinical utility for diagnosis, prognosis and treatment monitoring, the efficacy of a robust platform and universally accepted diagnostic criteria remain uncertain. We evaluate the diagnostic performance of a microfluidic CTC isolation platform using cytomorphologic criteria in patients undergoing lung cancer surgery.

METHODS

Blood was processed from 51 patients undergoing surgery for known or suspected lung cancer using the ClearBridge ClearCell FX system^TM (ClearBridge Biomedics, Singapore). Captured cells were stained on slides with haematoxylin and eosin (H&E) and independently assessed by two pathologist teams. Diagnostic performance was evaluated against the pathologists reported diagnosis of cancer from surgically obtained specimens.

RESULTS

Cancer was diagnosed in 43.1% and 54.9% of all cases. In early stage primary lung cancer, between the two reporting teams, a positive diagnosis of CTCs was made for 50% and 66.7% of patients. The agreement between the reporting teams was 80.4%, corresponding to a kappa-statistic of 0.61±0.11 (P<0.001), indicating substantial agreement. Sensitivity levels for the two teams were calculated as 59% (95% CI, 41-76%) and 41% (95% CI, 24-59%), with a specificity of 53% for both.

CONCLUSIONS

The performance of the tested microfluidic antibody independent device to capture CTCs using standard cytomorphological criteria provides the potential of a diagnostic blood test for lung cancer.

Circulating tumor cell clusters: What we know and what we expect (Review)

The major cause of cancer-associated mortality is tumor metastasis, a disease that is far from understood. Many studies have observed circulating tumor cells (CTCs) in patients' circulation systems, and a few latest investigations showed that CTC clusters have a potentially high capacity of metastasis. The capture and analysis of CTC clusters offer new insights into tumor metastasis and can facilitate the development of cancer treatments. We reviewed the research history of the CTC clusters, as well as the technologies used for detecting and isolating CTC clusters. In addition, we discuss the characteristics of CTC clusters and their roles in tumor dissemination. Clinical relevance of CTC clusters was also implicated in currently limited data. Moving forward, the next frontier in this field is to develop more efficient capture methods and decipher conundrums of characterization of CTC clusters. This will ultimately identify the clinical value of CTC clusters as a biomarker and therapeutic target.

Longitudinally collected CTCs and CTC-clusters and clinical outcomes of metastatic breast cancer

PURPOSE

Circulating tumor cell (CTC) is a well-established prognosis predictor for metastatic breast cancer (MBC), and CTC-cluster exhibits significantly higher metastasis-promoting capability than individual CTCs. Because measurement of CTCs and CTC-clusters at a single time point may underestimate their prognostic values, we aimed to analyze longitudinally collected CTCs and CTC-clusters in MBC prognostication.

METHODS

CTCs and CTC-clusters were enumerated in 370 longitudinally collected blood samples from 128 MBC patients. The associations between baseline, first follow-up, and longitudinal enumerations of CTCs and CTC-clusters with patient progression-free survival (PFS) and overall survival (OS) were analyzed using Cox proportional hazards models.

RESULTS

CTC and CTC-cluster counts at both baseline and first follow-up were significantly associated with patient PFS and OS. Time-dependent analysis of longitudinally collected samples confirmed the significantly unfavorable PFS and OS in patients with ≥5 CTCs, and further demonstrated the independent prognostic values by CTC-clusters compared to CTC-enumeration alone. Longitudinal analyses also identified a link between the size of CTC-clusters and patient OS: compared to the patients without any CTC, those with 2-cell CTC-clusters and ≥3-cell CTC-clusters had a hazard ratio (HR) of 7.96 [95 % confidence level (CI) 2.00-31.61, P = 0.003] and 14.50 (3.98-52.80, P < 0.001), respectively.

CONCLUSIONS

In this novel time-dependent analysis of longitudinally collected CTCs and CTC-clusters, we showed that CTC-clusters added additional prognostic values to CTC enumeration alone, and a larger-size CTC-cluster conferred a higher risk of death in MBC patients.

Circulating tumor cells versus circulating tumor DNA in lung cancer-which one will win?

Liquid biopsies appear to be a reliable alternative to conventional biopsies that can provide both precise molecular data useful for improving the clinical management of lung cancer patients as well as a less invasive way of monitoring tumor behavior. These advances are supported by important biotechnological developments in the fields of circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA). Analysis of CTCs and ctDNA may be useful in treatment selection, for response monitoring, and in studying resistance mechanisms. This review focuses on the most recent technological achievements and the most relevant clinical applications for lung cancer patients in the CTC and ctDNA fields, highlighting those that are already (or are close to) being implemented in daily clinical practice.

Regulation of prostate cancer progression by the tumor microenvironment

Prostate cancer remains the most frequently diagnosed cancer in men in North America, and despite recent advances in treatment patients with metastatic disease continue to have poor five-year survival rates. Recent studies in prostate cancer have revealed the critical role of the tumor microenvironment in the initiation and progression to advanced disease. Experimental data have uncovered a reciprocal relationship between the cells in the microenvironment and malignant tumor cells in which early changes in normal tissue microenvironment can promote tumorigenesis and in turn tumor cells can promote further pro-tumor changes in the microenvironment. In the tumor microenvironment, the presence of persistent immune infiltrates contributes to the recruitment and reprogramming of other non-immune stromal cells including cancer-associated fibroblasts and a unique recently identified population of metastasis-initiating cells (MICs). These MICs, which can also be found as part of the circulating tumor cell (CTC) population in PC patients, promote cancer cell transformation, enhance metastatic potential and confer therapeutic resistance. MICs act can on other cells within the tumor microenvironment in part by secreting exosomes that reprogram adjacent stromal cells to create a more favorable tumor microenvironment to support continued cancer growth and progression. We review here the current data on the intricate relationship between inflammation, reactive stroma, tumor cells and disease progression in prostate cancer.

The Challenges of Detecting Circulating Tumor Cells in Sarcoma

Sarcomas are a heterogeneous group of malignant neoplasms of mesenchymal origin, many of which have a propensity to develop distant metastases. Cancer cells that have escaped from the primary tumor are able to invade into surrounding tissues, to intravasate into the bloodstream to become circulating tumor cells (CTCs), and are responsible for the generation of distant metastases. Due to the rarity of these tumors and the absence of specific markers expressed by sarcoma tumor cells, the characterization of sarcoma CTCs has to date been relatively limited. Current techniques for isolating sarcoma CTCs are based on size criteria, the identification of circulating cells that express either common mesenchymal markers, sarcoma-specific markers, such as CD99, CD81, or PAX3, and chromosomal translocations found in certain sarcoma subtypes, such as EWS-FLI1 in Ewing’s sarcoma, detection of osteoblast-related genes, or measurement of the activity of specific metabolic enzymes. Further studies are needed to improve the isolation and characterization of sarcoma CTCs, to demonstrate their clinical significance as predictive and/or prognostic biomarkers, and to utilize CTCs as a tool for investigating the metastatic process in sarcoma and to identify novel therapeutic targets. The present review provides a short overview of the most recent literature on CTCs in sarcoma.

Challenges in molecular testing in non-small-cell lung cancer patients with advanced disease

Lung cancer diagnostics have progressed greatly in the previous decade. Development of molecular testing to identify an increasing number of potentially clinically actionable genetic variants, using smaller samples obtained via minimally invasive techniques, is a huge challenge. Tumour heterogeneity and cancer evolution in response to therapy means that repeat biopsies or circulating biomarkers are likely to be increasingly useful to adapt treatment as resistance develops. We highlight some of the current challenges faced in clinical practice for molecular testing of EGFR, ALK, and new biomarkers such as PDL1. Implementation of next generation sequencing platforms for molecular diagnostics in non-small-cell lung cancer is increasingly common, allowing testing of multiple genetic variants from a single sample. The use of next generation sequencing to recruit for molecularly stratified clinical trials is discussed in the context of the UK Stratified Medicine Programme and The UK National Lung Matrix Trial.

Affinity Versus Label-Free Isolation of Circulating Tumor Cells: Who Wins?

The study of circulating tumor cells (CTCs) has been made possible by many technological advances in their isolation. Their isolation has seen many fronts, but each technology brings forth a new set of challenges to overcome. Microfluidics has been a key player in the capture of CTCs and their downstream analysis, with the aim of shedding light into their clinical application in cancer and metastasis. Researchers have taken diverging paths to isolate such cells from blood, ranging from affinity-based isolation targeting surface antigens expressed on CTCs, to label-free isolation taking advantage of the size differences between CTCs and other blood cells. For both major groups, many microfluidic technologies have reported high sensitivity and specificity for capturing CTCs. However, the question remains as to the superiority among these two isolation techniques, specifically to identify different CTC populations. This review highlights the key aspects of affinity and label-free microfluidic CTC technologies, and discusses which of these two would be the highest benefactor for the study of CTCs.

An Aqueous Extract of Marine Microalgae Exhibits Antimetastatic Activity through Preferential Killing of Suspended Cancer Cells and Anticolony Forming Activity

Research on marine natural products as potential anticancer agents is still limited. In the present study, an aqueous extract of a Canadian marine microalgal preparation was assessed for anticancer activities using various assays and cell lines of human cancers, including lung, prostate, stomach, breast, and pancreatic cancers, as well as an osteosarcoma. In vitro, the microalgal extract exhibited marked anticolony forming activity. In addition, it was more toxic, as indicated by increased apoptosis, to nonadherent cells (grown in suspension) than to adherent cells. In vivo, an antimetastatic effect of the extract was observed in NOD-SCID mice carrying subrenal capsule xenografts of PC3 prostate cancer cells. The results of the present study suggest that the antimetastatic effect of the aqueous microalgal extract is based on inhibition of colony forming ability of cancer cells and the preferential killing of suspended cancer cells. Further research aimed at identification of the molecular basis of the anticancer activities of the microalgal extract appears to be warranted.

Does the mobilization of circulating tumour cells during cancer therapy cause metastasis?

Despite progressive improvements in the management of patients with locoregionally confined, advanced-stage solid tumours, distant metastasis remains a very common - and usually fatal - mode of failure after attempted curative treatment. Surgery and radiotherapy are the primary curative modalities for these patients, often combined with each other and/or with chemotherapy. Distant metastasis occurring after treatment can arise from previously undetected micrometastases or, alternatively, from persistent locoregional disease. Another possibility is that treatment itself might sometimes cause or promote metastasis. Surgical interventions in patients with cancer, including biopsies, are commonly associated with increased concentrations of circulating tumour cells (CTCs). High CTC numbers are associated with an unfavourable prognosis in many cancers. Radiotherapy and systemic antitumour therapies might also mobilize CTCs. We review the preclinical and clinical data concerning cancer treatments, CTC mobilization and other factors that might promote metastasis. Contemporary treatment regimens represent the best available curative options for patients who might otherwise die from locally confined, advanced-stage cancers; however, if such treatments can promote metastasis, this process must be understood and addressed therapeutically to improve patient survival.

Circulating Tumor Cells and Circulating Tumor DNA: Challenges and Opportunities on the Path to Clinical Utility

Recent technological advances have enabled the detection and detailed characterization of circulating tumor cells (CTC) and circulating tumor DNA (ctDNA) in blood samples from patients with cancer. Often referred to as a "liquid biopsy," CTCs and ctDNA are expected to provide real-time monitoring of tumor evolution and therapeutic efficacy, with the potential for improved cancer diagnosis and treatment. In this review, we focus on these opportunities as well as the challenges that should be addressed so that these tools may eventually be implemented into routine clinical care.

The Significance of Epithelial-to-Mesenchymal Transition for Circulating Tumor Cells

Epithelial to mesenchymal transition (EMT) is a process involved in embryonic development, but it also plays a role in remote metastasis formation in tumor diseases. During this process cells lose their epithelial features and adopt characteristics of mesenchymal cells. Thereby single tumor cells, which dissolve from the primary tumor, are enabled to invade the blood vessels and travel throughout the body as so called "circulating tumor cells" (CTCs). After leaving the blood stream the reverse process of EMT, the mesenchymal to epithelial transition (MET) helps the cells to seed in different tissues, thereby generating the bud of metastasis formation. As metastasis is the main reason for tumor-associated death, CTCs and the EMT process are in the focus of research in recent years. This review summarizes what was already found out about the molecular mechanisms driving EMT, the consequences of EMT for tumor cell detection, and suitable markers for the detection of CTCs which underwent EMT. The research work done in this field could open new roads towards combating cancer.

Circulating Tumor Cells

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

Progress in the research on the mechanism of bone metastasis in lung cancer

Lung cancer is still the predominant cause of cancer-associated mortality worldwide. The bone metastasis of lung cancer brings great suffering to the patient. Previous advances have provided insights into the mechanism of bone metastasis. Previous research has investigated lung cancer stem cells and three steps were determined for the lung cancer cells to metastasize to the bone: i) Escaping from the primary tumor; ii) moving in the circulation; iii) colonizing in the bone. Key molecules are involved in each of these process. Although there is a close association and similarity, dynamic microenvironments affect these processes. The receptor activator of nuclear factor-κB (RANK)/RANKL axis serves a vital role in the regulation of the generation and activation of osteoclasts during the osteolytic lesion. However, the specific molecules for the lung cancer cells to metastasize to the bone require further research and exploration. The present study aimed to investigate the relative molecular mechanisms of bone metastasis in lung cancer in recent years, providing a general understanding about the features of lung cancer preferences to bone, and discussing other things that require investigation.

Coupling the modules of EMT and stemness: A tunable 'stemness window' model

Metastasis of carcinoma involves migration of tumor cells to distant organs and initiate secondary tumors. Migration requires a complete or partial Epithelial-to-Mesenchymal Transition (EMT), and tumor-initiation requires cells possessing stemness. Epithelial cells (E) undergoing a complete EMT to become mesenchymal (M) have been suggested to be more likely to possess stemness. However, recent studies suggest that stemness can also be associated with cells undergoing a partial EMT (hybrid E/M phenotype). Therefore, the correlation between EMT and stemness remains elusive. Here, using a theoretical framework that couples the core EMT and stemness modules (miR-200/ZEB and LIN28/let-7), we demonstrate that the positioning of ‘stemness window’ on the ‘EMT axis’ need not be universal; rather it can be fine-tuned. Particularly, we present OVOL as an example of a modulating factor that, due to its coupling with miR-200/ZEB/LIN28/let-7 circuit, fine-tunes the EMT-stemness interplay. Coupling OVOL can inhibit the stemness likelihood of M and elevate that of the hybrid E/M (partial EMT) phenotype, thereby pulling the ‘stemness window’ away from the M end of ‘EMT axis’. Our results unify various apparently contradictory experimental findings regarding the interconnection between EMT and stemness, corroborate the emerging notion that partial EMT associates with stemness, and offer new testable predictions.

Method for semi-automated microscopy of filtration-enriched circulating tumor cells

BACKGROUND

Circulating tumor cell (CTC)-filtration methods capture high numbers of CTCs in non-small-cell lung cancer (NSCLC) and metastatic prostate cancer (mPCa) patients, and hold promise as a non-invasive technique for treatment selection and disease monitoring. However filters have drawbacks that make the automation of microscopy challenging. We report the semi-automated microscopy method we developed to analyze filtration-enriched CTCs from NSCLC and mPCa patients.

METHODS

Spiked cell lines in normal blood and CTCs were enriched by ISET (isolation by size of epithelial tumor cells). Fluorescent staining was carried out using epithelial (pan-cytokeratins, EpCAM), mesenchymal (vimentin, N-cadherin), leukocyte (CD45) markers and DAPI. Cytomorphological staining was carried out with Mayer-Hemalun or Diff-Quik. ALK-, ROS1-, ERG-rearrangement were detected by filter-adapted-FISH (FA-FISH). Microscopy was carried out using an Ariol scanner.

RESULTS

Two combined assays were developed. The first assay sequentially combined four-color fluorescent staining, scanning, automated selection of CD45(-) cells, cytomorphological staining, then scanning and analysis of CD45(-) cell phenotypical and cytomorphological characteristics. CD45(-) cell selection was based on DAPI and CD45 intensity, and a nuclear area >55 μm(2). The second assay sequentially combined fluorescent staining, automated selection of CD45(-) cells, FISH scanning on CD45(-) cells, then analysis of CD45(-) cell FISH signals. Specific scanning parameters were developed to deal with the uneven surface of filters and CTC characteristics. Thirty z-stacks spaced 0.6 μm apart were defined as the optimal setting, scanning 82 %, 91 %, and 95 % of CTCs in ALK-, ROS1-, and ERG-rearranged patients respectively. A multi-exposure protocol consisting of three separate exposure times for green and red fluorochromes was optimized to analyze the intensity, size and thickness of FISH signals.

CONCLUSIONS

The semi-automated microscopy method reported here increases the feasibility and reliability of filtration-enriched CTC assays and can help progress towards their validation and translation to the clinic.

Prognostic impact of circulating tumor cell apoptosis and clusters in serial blood samples from patients with metastatic breast cancer in a prospective observational cohort

Background

Presence of circulating tumor cells (CTCs) is a validated prognostic marker in metastatic breast cancer. Additional prognostic information may be obtained by morphologic characterization of CTCs. We explored whether apoptotic CTCs, CTC clusters and leukocytes attached to CTCs are associated with breast cancer subtype and prognosis at base-line (BL) and in follow-up (FU) blood samples in patients with metastatic breast cancer scheduled for first-line systemic treatment.

Methods

Patients with a first metastatic breast cancer event were enrolled in a prospective observational study prior to therapy initiation and the CellSearch system (Janssen Diagnostics) was used for CTC enumeration and characterization. We enrolled patients (N = 52) with ≥5 CTC/7.5 ml blood at BL (median 45, range 5–668) and followed them with blood sampling for 6 months during therapy. CTCs were evaluated for apoptotic changes, CTC clusters (≥3 nuclei), and leukocytes associated with CTC (WBC-CTC, ≥1 CTC + ≥1 leukocytes) at all time-points by visual examination of the galleries generated by the CellTracks Analyzer.

Results

At BL, patients with triple-negative and HER2-positive breast cancer had blood CTC clusters present more frequently than patients with hormone receptor-positive cancer (P = 0.010). No morphologic characteristics were associated with prognosis at BL, whereas patients with apoptotic CTCs or clusters in FU samples had worse prognosis compared to patients without these characteristics with respect to progression-free (PFS) and overall survival (OS) (log-rank test: P = 0.0012 or lower). Patients with apoptotic or clustered CTCs at any time-point had impaired prognosis in multivariable analyses adjusting for number of CTCs and other prognostic factors (apoptosis: HR_OS = 25, P < 0.001; cluster: HR_OS = 7.0, P = 0.006). The presence of WBC-CTCs was significantly associated with an inferior prognosis in terms of OS at 6 months in multivariable analysis.

Conclusions

Patients with a continuous presence of apoptotic or clustered CTCs in FU samples after systemic therapy initiation had worse prognosis than patients without these CTC characteristics. In patients with ≥5 CTC/7.5 ml blood at BL, morphologic characterization of persistent CTCs could be an important prognostic marker during treatment, in addition to CTC enumeration alone.

Clinical Trials (NCT01322893), registration date 21 March 2011

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2406-y) contains supplementary material, which is available to authorized users.

Cancer Stem Cells, Epithelial to Mesenchymal Markers, and Circulating Tumor Cells in Small Cell Lung Cancer

BACKGROUND

Small cell lung cancer (SCLC) has a poor prognosis, and even with localized (limited) disease, the 5-year survival has only been around 20%. Elevated levels of circulating tumor cells (CTCs) have been associated with a worse prognosis, and markers of cancer stem cells (CSCs) and epithelial to mesenchymal transition have been associated with increased chemoresistance and metastatic spread in SCLC.

PATIENTS AND METHODS

The biopsy specimens of 38 SCLC patients were used for marker evaluation by immunohistochemistry. The markers for CSCs were CD44 and SOX2. The markers for epithelial to mesenchymal transition were E-cadherin, epithelial cell adhesion molecule, cytokeratins 8, 18, and 19, vimentin, and c-MET. Staining was scored as low (weak) or high (strong) intensity for SOX2, epithelial cell adhesion molecule, cytokeratins 8, 18, and 19, and c-MET and using the immunoreactive score for CD44, E-cadherin, and vimentin, expressed as low or high expression.

RESULTS

High expression of c-MET (c-MET^H) and low expression of E-cadherin (E-cad^L) showed a trend toward a better prognosis (P = .07 and P = .09, respectively). The combination of c-MET^H and E-cad^L resulted in significantly better survival (P = .007). The tested markers were not associated with CTCs, although a trend was seen for c-MET^HE-cad^L (P = .09) with low CTCs. The CSC markers SOX2 and CD44 were not associated with overall survival in this patient cohort.

CONCLUSION

SCLC with a mesenchymal-like phenotype (c-MET^HE-cad^L) is associated with longer survival and showed a trend toward lower CTCs.

Tumourigenic non-small-cell lung cancer mesenchymal circulating tumour cells: a clinical case study

BACKGROUND

Over the past decade, numerous reports describe the generation and increasing utility of non-small-cell lung cancer (NSCLC) patient-derived xenografts (PDX) from tissue biopsies. While PDX have proven useful for genetic profiling and preclinical drug testing, the requirement of a tissue biopsy limits the available patient population, particularly those with advanced oligometastatic disease. Conversely, 'liquid biopsies' such as circulating tumour cells (CTCs) are minimally invasive and easier to obtain. Here, we present a clinical case study of a NSCLC patient with advanced metastatic disease, a never smoker whose primary tumour was EGFR and ALK wild-type. We demonstrate for the first time, tumorigenicity of their CTCs to generate a patient CTC-derived eXplant (CDX).

PATIENTS AND METHODS

CTCs were enriched at diagnosis and again 2 months later during disease progression from 10 ml blood from a 48-year-old NSCLC patient and implanted into immunocompromised mice. Resultant tumours were morphologically, immunohistochemically, and genetically compared with the donor patient's diagnostic specimen. Mice were treated with cisplatin and pemetrexed to assess preclinical efficacy of the chemotherapy regimen given to the donor patient.

RESULTS

The NSCLC CDX expressed lung lineage markers TTF1 and CK7 and was unresponsive to cisplatin and pemetrexed. Examination of blood samples matched to that used for CDX generation revealed absence of CTCs using the CellSearch EpCAM-dependent platform, whereas size-based CTC enrichment revealed abundant heterogeneous CTCs of which ∼80% were mesenchymal marker vimentin positive. Molecular analysis of the CDX, mesenchymal and epithelial CTCs revealed a common somatic mutation confirming tumour origin and showed CDX RNA and protein profiles consistent with the predominantly mesenchymal phenotype.

CONCLUSIONS

This study shows that the absence of NSCLC CTCs detected by CellSearch (EpCAM(+)) does not preclude CDX generation, highlighting epithelial to mesenchymal transition and the functional importance of mesenchymal CTCs in dissemination of this disease.

Distribution and clinical significance of circulating tumor cells in nasopharyngeal carcinoma

OBJECTIVE

Nasopharyngeal carcinoma is one of the leading malignancies with obscure etiology. Circulating tumor cells have been showed to intimately correlate with characteristics in different kinds of cancer. But links between circulating tumor cells and nasopharyngeal carcinoma were still lacking. Therefore, we explored circulating tumor cells' distribution in nasopharyngeal carcinoma and their possible associations with nasopharyngeal carcinoma.

METHODS

Firstly, we found that the positive ratio of circulating tumor cells is extremely high in four stages of nasopharyngeal carcinoma. Meanwhile, positive ratios of mesenchymal circulating tumor cells were higher in early stages of nasopharyngeal carcinoma. Apart from epithelial circulating tumor cells, total, hybrid and mesenchymal circulating tumor cells were correlated with nasopharyngeal carcinoma clinical stage.

RESULTS

Our results showed that hybrid and mesenchymal circulating tumor cells were associated with nasopharyngeal carcinoma metastasis (both distant and lymph node) and smoking. Meanwhile, hybrid circulating tumor cells expressed the highest Epstein-Barr virus proteins and deoxyribonucleic acid in three types of circulating tumor cells. Moreover, we found that Epstein-Barr virus proteins viral-caspid antigen-immunoglobulin A (VCA/IgA) and early antigen-immunoglobulin A (EA/IgA), but not Epstein-Barr virus-deoxyribonucleic acid, had a closed association with nasopharyngeal carcinoma metastasis. However, Epstein-Barr virus hallmarks failed to associate with other nasopharyngeal carcinoma characteristics. Furthermore, we confirmed that matrix metalloproteinase 9 existed in circulating tumor cells and expressed most in mesenchymal circulating tumor cells. In addition, matrix metalloproteinase 9-expressed extent in hybrid circulating tumor cells is somewhat different from epithelial and mesenchymal circulating tumor cells in matrix metalloproteinase 9-positive circulating tumor cells. Nevertheless, matrix metalloproteinase 9 had no relationship with other nasopharyngeal carcinoma characteristics. Finally, our results showed that circulating tumor cells were decreased in patients after therapies.

CONCLUSION

Taken together, circulating tumor cells were tightly correlated with nasopharyngeal carcinoma characteristics. In addition, Epstein-Barr virus was associated with nasopharyngeal carcinoma metastasis. Of note, decreased circulating tumor cells indicated a favorable curative effect in nasopharyngeal carcinoma patients.

OVOL guides the epithelial-hybrid-mesenchymal transition

Metastasis involves multiple cycles of Epithelial-to-Mesenchymal Transition (EMT) and its reverse-MET. Cells can also undergo partial transitions to attain a hybrid epithelial/mesenchymal (E/M) phenotype that has maximum cellular plasticity and allows migration of Circulating Tumor Cells (CTCs) as a cluster. Hence, deciphering the molecular players helping to maintain the hybrid E/M phenotype may inform anti-metastasis strategies. Here, we devised a mechanism-based mathematical model to couple the transcription factor OVOL with the core EMT regulatory network miR-200/ZEB that acts as a three-way switch between the E, E/M and M phenotypes. We show that OVOL can modulate cellular plasticity in multiple ways - restricting EMT, driving MET, expanding the existence of the hybrid E/M phenotype and turning both EMT and MET into two-step processes. Our theoretical framework explains the differences between the observed effects of OVOL in breast and prostate cancer, and provides a platform for investigating additional signals during metastasis.

CPEB4 and IRF4 expression in peripheral mononuclear cells are potential prognostic factors for advanced lung cancer

BACKGROUND/PURPOSE

Lung cancer is a heterogeneous disease with varied outcomes. Molecular markers are eagerly investigated to predict a patient's treatment response or outcome. Previous studies used frozen biopsy tissues to identify crucial genes as prognostic markers. We explored the prognostic value of peripheral blood (PB) molecular signatures in patients with advanced non-small cell lung cancer (NSCLC).

METHODS

Peripheral blood mononuclear cell (PBMC) fractions from patients with advanced NSCLC were applied for RNA extraction, cDNA synthesis, and real-time polymerase chain reaction (PCR) for the expression profiling of eight genes: DUSP6, MMD, CPEB4, RNF4, STAT2, NF1, IRF4, and ZNF264. Proportional hazard (PH) models were constructed to evaluate the association of the eight expressing genes and multiple clinical factors [e.g., sex, smoking status, and Charlson comorbidity index (CCI)] with overall survival.

RESULTS

One hundred and forty-one patients with advanced NSCLC were enrolled. They included 109 (77.30%) patients with adenocarcinoma, 12 (8.51%) patients with squamous cell carcinoma, and 20 (14.18%) patients with other pathological lung cancer types. A PH model containing two significant survival-associated genes, CPEB4 and IRF4, could help in predicting the overall survival of patients with advanced stage NSCLC [hazard ratio (HR) = 0.48, p < 0.0001). Adding multiple clinical factors further improved the prediction power of prognosis (HR = 0.33; p < 0.0001).

CONCLUSION

Molecular signatures in PB can stratify the prognosis in patients with advanced NSCLC. Further prospective, interventional clinical trials should be performed to test if gene profiling also predicts resistance to chemotherapy.

Clusters of circulating tumor cells traverse capillary-sized vessels

Multicellular aggregates of circulating tumor cells (CTC clusters) are potent initiators of distant organ metastasis. However, it is currently assumed that CTC clusters are too large to pass through narrow vessels to reach these organs. Here, we present evidence that challenges this assumption through the use of microfluidic devices designed to mimic human capillary constrictions and CTC clusters obtained from patient and cancer cell origins. Over 90% of clusters containing up to 20 cells successfully traversed 5- to 10-μm constrictions even in whole blood. Clusters rapidly and reversibly reorganized into single-file chain-like geometries that substantially reduced their hydrodynamic resistances. Xenotransplantation of human CTC clusters into zebrafish showed similar reorganization and transit through capillary-sized vessels in vivo. Preliminary experiments demonstrated that clusters could be disrupted during transit using drugs that affected cellular interaction energies. These findings suggest that CTC clusters may contribute a greater role to tumor dissemination than previously believed and may point to strategies for combating CTC cluster-initiated metastasis.

A novel label-free and reusable electrochemical cytosensor for highly sensitive detection and specific collection of CTCs

Circulating tumor cells (CTCs) contain a great deal of information of tumor phenotype. Therefore, highly sensitive detection and specific enrichment of CTCs are of intense interest. Herein, a label-free electrochemical impedance spectroscopy cytosensor with effective surface recognition between specific epithelial cell adhesion molecules (EpCAM) over-expressed on the cell membrane and EpCAM aptamer was developed for the detection of CTCs. After immobilization of 6-mercapto-1-hexanol (MCH) onto the gold electrode, the capture probe can be directionally inserted in MCH interspaces, which can improve the sensitivity of the cytosensor. A wide detection range from 30 to 1×10(6)cellsmL(-1) with a detection limit as low as 10cellsmL(-1) is reached on the condition of acceptable stability and reproducibility. The cytosensor can easily distinguish CTCs from the real blood sample due to the specific combination of EpCAM and EpCAM aptamer. Furthermore, the cytosensor can be reused 8 times and enrich CTCs by Uracil DNA Excision Mix specific cleaving the deoxyuridines (dUs) of the aptamer. The collected CTCs can contribute to further study. Thus, we reported that this cytosensor is a promising technique for the early monitoring and therapy of cancer.

Detection of Circulating Tumor Cells Using a Novel Immunomagnetic Bead Method in Lung Cancer Patients

BACKGROUND

Circulating tumor cells (CTCs) are detectable in peripheral blood of metastatic lung cancer patients. In this article, we evaluate a new CTC separation method based on a combination of anti-EpCAM and immunomagnetic beads with the aim to detect CTCs more conveniently and specifically.

METHODS

Lung cancer cells were magnetically labeled by anti-EpCAM magnetic beads, and subsequently captured by magnetic separation using our novel device. Isolated lung cancer cells were identified by pathomorphological by hematoxylin-eosin staining protocol. The system was used to detect CTCs in 2 ml blood. Blood samples of healthy donors spiked with lung cancer cell line A549 cells were used to determine the sensitivity and specificity of the method. Prevalence of CTCs was examined in samples from 56 patients with lung cancer.

RESULTS

Regression analysis of number of recovered versus spiked A549 cells yielded a coefficient of determination of R(2) = 0.996 (P < 0.001). The average recovery was 68% or more at each spiking level. The coefficient of variation increased as the number of spiked cells decreased, ranging from 6.4% (1,000-cell spike) to 18.4% (50-cell spike). Forty-nine of the fifty-six patients (87.5%) were found to have CTCs in peripheral blood. None of the 2 ml peripheral blood samples of the 20 healthy subjects analyzed were found to have CTCs.

CONCLUSIONS

This novel turbulence device provides a new tool allowing for feasible and specific detection of CTCs in lung cancer patients. It is likely clinically useful in diagnosis and monitoring of lung cancer and may have a role in clinical decision making.

Perioperative circulating tumor cells in surgical patients with non-small cell lung cancer: does surgical manipulation dislodge cancer cells thus allowing them to pass into the peripheral blood?

PURPOSE

We herein evaluated the status of circulating tumor cells (CTC) dislodged from the tumor during surgery in patients who underwent pulmonary resection for non-small cell lung cancer (NSCLC) to assess the clinical implications.

METHODS

Tumor cells in the peripheral arterial blood before surgery (Before) and immediately after lung resection (After) and in the blood from the pulmonary vein of the resected lung were detected using a size selective method. The clinicopathological characteristics and the prognosis were then analyzed according to the CTC status: no tumor cells detected (N), single tumor cell or total number less than 4 cells (S), and existence of clustered cells (C).

RESULTS

According to the CTC status, the patients were classified into the following three groups: Before-C and After-C, Group I (n = 6); Before-S or N and After-C, Group II (n = 9); and Before-S or N and After-S or N, Group III (n = 8). Group III showed a high rate of p-stage IA, smaller tumor size, lower CEA level, lower SUVmax level, and a higher relapse-free survival rate than the other groups.

CONCLUSIONS

CTCs were detected in patients after undergoing lung resection, some of which may have been dislodged by the surgical procedure. The presence of clustered CTCs after the operation indicated an unfavorable outcome.

Clinical Significance of Circulating Tumor Microemboli as a Prognostic Marker in Patients with Pancreatic Ductal Adenocarcinoma

BACKGROUND

Characterization of circulating tumor cells (CTCs) has been used to provide prognostic, predictive, and pharmacodynamic information in many different cancers. However, the clinical significance of CTCs and circulating tumor microemboli (CTM) in patients with pancreatic ductal adenocarcinoma (PDAC) has yet to be determined.

METHODS

In this prospective study, CTCs and CTM were enumerated in the peripheral blood of 63 patients with PDAC before treatment using anti-EpCAM (epithelial cell adhesion molecule)–conjugated supported lipid bilayer–coated microfluidic chips. Associations of CTCs and CTM with patients' clinical factors and prognosis were determined.

RESULTS

CTCs were abundant [mean (SD), 70.2 (107.6)] and present in 81% (51 of 63) of patients with PDAC. CTM were present in 81% (51 of 63) of patients with mean (SD) 29.7 (1101.4). CTM was an independent prognostic factor of overall survival (OS) and progression free survival (PFS). Patients were stratified into unfavorable and favorable CTM groups on the basis of CTM more or less than 30 per 2 mL blood, respectively. Patients with baseline unfavorable CTM, compared with patients with favorable CTM, had shorter PFS (2.7 vs 12.1 months; P &lt; 0.0001) and OS (6.4 vs 19.8 months; P &lt; 0.0001). Differences persisted if we stratified patients into early and advanced diseases. The number of CTM before treatment was an independent predictor of PFS and OS after adjustment for clinically significant factors.

CONCLUSIONS

The number of CTM, instead of CTCs, before treatment is an independent predictor of PFS and OS in patients with PDAC.

Clinical evaluation of a novel microfluidic device for epitope-independent enrichment of circulating tumour cells in patients with small cell lung cancer

Circulating tumour cells (CTCs) have potential utility as minimally-invasive biomarkers to aid cancer treatment decision making. However, many current CTC technologies enrich CTCs using specific surface epitopes that do not necessarily reflect CTC heterogeneity. Here we evaluated the epitope-independent Parsortix system which enriches CTCs based on size and rigidity using both healthy normal volunteer blood samples spiked with tumour cells and blood samples from patients with small cell lung cancer (SCLC). Blood samples were maintained unfractionated at room temperature for up to 4 days followed by plasma removal for circulating free DNA (cfDNA) isolation and direct application of the remaining cell component to the Parsortix system. For tumour cells expressing the EpCAM cell surface marker the numbers of spiked cells retained using the Parsortix system and by EpCAM-positive selection using CellSearch® were not significantly different, whereas only the Parsortix system showed strong enrichment of cells with undetectable EpCAM expression. In a pilot clinical study we banked both enriched CTCs as well as plasma from SCLC patient blood samples. Upon retrieval of the banked Parsortix cellular samples we could detect cytokeratin positive CTCs in all 12 SCLC patients tested. Interestingly, processing parallel samples from the same patients by EpCAM enrichment using CellSearch® revealed only 83% (10/12) with cytokeratin positive CTCs indicating the Parsortix system is enriching for EpCAM negative SCLC CTCs. Our combined results indicate the Parsortix system is a valuable tool for combined cfDNA isolation and CTC enrichment that enables CTC analysis to be extended beyond dependence on surface epitopes.