Circulating tumor cells: advances in detection methods, biological issues, and clinical relevance

Circulating tumor cells in patients with cervical cancer undergoing chemoradiotherapy combined with brachytherapy

Circulating tumor cells (CTCs) have significant potential to become an important tool for monitoring the effects of treatment in solid tumors. The present study reports the occurance of CTCs in cervical cancer (CC) patients during radical chemoradiotherapy (CRT), including brachytherapy (BRT), and during the follow-up period. Patients diagnosed with CC treated with radical CRT were included in the study (n=30). A total of 167 CTC-tests (MetaCell®) were provided at predefined testing time points during the study follow-up (e.g., before CRT, after CRT, every three months of follow-up). In parallel with CTC-testing, SCC-Ag were measured to compare their predictive values during treatment. CTCs were present in 96% (25/26) of patients at the time of diagnosis and in 61% (14/23) after treatment. Patients who relapsed during the 36-month follow-up (n=10) showed an elevation in pre-treatment CTC- numbers, similarly there was a significant increase in pre-treatment SCC-Ag. As next, an increased number of CTCs was observed approximately 12 weeks before relapse was diagnosed by standard imaging modalities (MRI, US, PET-CT) in 3 of 4 patients. In addition to standardized vital cytomorphology of enriched CTCs, quantitative PCR (qPCR) was used to inform the nature of CTCs before treatment. Analysis revealed increased SOX2 and POUSF expression in CTCs in the group of patients with recurrence (P < 0.02). Disease aggressiveness may be related to increased expression of stem cell markers, as found in samples from relapsed patients. CTCs may be an aid to assess tumor burden and disease aggressiveness. An increase in CTCs precedes an increase in SCC-Ag and confirmation of relapse by imaging, as shown in our study.

Understanding crosstalk of organ tropism, tumor microenvironment and noncoding RNAs in breast cancer metastasis

Cancer metastasis is one of the major clinical challenges worldwide due to limited existing effective treatments. Metastasis roots from the host organ of origin and gradually migrates to different regional and distant organs. In different breast cancer subtypes, different organs like bones, liver, lungs and brain are targeted by the metastatic tumor cells. Cancer renders mortality to their respective metastasizing sites like bones, brain, liver, and lungs. Metastatic breast cancers are best treated and managed if detected at an early stage. Metastasis is regulated by various molecular activators and suppressors. The conventional theory of 'seed and soil' states that metastatic tumor cells move to tumor microenvironment that has favorable conditions like blood flow for them to grow just like seeds grows when planted in fertile land. Additionally, different coding as well as non-coding RNAs play a very significant role in the process of metastasis by modulating their expression levels leading to a crosstalk of various tumorigenic cascades. Treatments for metastasis is also very critical in controlling this lethal process. Detecting breast cancer metastasis at an early stage is crucial for managing and predicting metastatic progression. In this review, we have compiled several factors that can be targeted to manage the onset and gradual stages of breast cancer metastasis.

Deep neural network for discovering metabolism-related biomarkers for lung adenocarcinoma

Introduction

Lung cancer is a major cause of illness and death worldwide. Lung adenocarcinoma (LUAD) is its most common subtype. Metabolite-mRNA interactions play a crucial role in cancer metabolism. Thus, metabolism-related mRNAs are potential targets for cancer therapy.

Methods

This study constructed a network of metabolite-mRNA interactions (MMIs) using four databases. We retrieved mRNAs from the Tumor Genome Atlas (TCGA)-LUAD cohort showing significant expressional changes between tumor and non-tumor tissues and identified metabolism-related differential expression (DE) mRNAs among the MMIs. Candidate mRNAs showing significant contributions to the deep neural network (DNN) model were mined. Using MMIs and the results of function analysis, we created a subnetwork comprising candidate mRNAs and metabolites.

Results

Finally, 10 biomarkers were obtained after survival analysis and validation. Their good prognostic value in LUAD was validated in independent datasets. Their effectiveness was confirmed in the TCGA and an independent Clinical Proteomic Tumor Analysis Consortium (CPTAC) dataset by comparison with traditional machine-learning models.

Conclusion

To summarize, 10 metabolism-related biomarkers were identified, and their prognostic value was confirmed successfully through the MMI network and the DNN model. Our strategy bears implications to pave the way for investigating metabolic biomarkers in other cancers.

In vivo flow cytometry reveals an anti-metastatic effect of Rujifang in triple-negative breast cancer

Breast cancer is the most common cancer, and triple-negative breast cancer (TNBC) has the highest metastasis and mortality rate among all breast cancer subtypes. Rujifang is a traditional Chinese medicine formula with many years of clinical application in breast cancer treatment. Here, we aim to investigate the effects of Rujifang on circulating tumor cell (CTC) dynamics and the tumor microenvironment in a ZsGreen/luciferase double-labeled TNBC orthotopic model. We report that the number of CTCs monitored by in vivo flow cytometry (IVFC) strongly correlates with disease progression. Rujifang treatment decreased the number of CTCs and suppressed the distant metastasis of TNBC. Moreover, immunofluorescence analysis revealed that Rujifang treatment could affect the tumor microenvironment by downregulating Kindlin-1, which has been reported to promote metastasis of TNBC. Our study provides evidence of the anti-metastatic effect of Rujifang against TNBC in an animal model using fluorescent cell lines. The results suggest the potential therapeutic value of Rujifang as an anti-metastatic drug, however, further clinical trials are needed to validate these findings in humans.

The Role of Artificial Intelligence in the Detection and Implementation of Biomarkers for Hepatocellular Carcinoma: Outlook and Opportunities

Liver cancer is a leading cause of cancer-related death worldwide, and its early detection and treatment are crucial for improving morbidity and mortality. Biomarkers have the potential to facilitate the early diagnosis and management of liver cancer, but identifying and implementing effective biomarkers remains a major challenge. In recent years, artificial intelligence has emerged as a promising tool in the cancer sphere, and recent literature suggests that it is very promising in facilitating biomarker use in liver cancer. This review provides an overview of the status of AI-based biomarker research in liver cancer, with a focus on the detection and implementation of biomarkers for risk prediction, diagnosis, staging, prognostication, prediction of treatment response, and recurrence of liver cancers.

MMP9 and TYROBP affect the survival of circulating tumor cells in clear cell renal cell carcinoma by adapting to tumor immune microenvironment

Circulating tumor cells (CTCs) play a key role in tumor metastasis. CTCs have altered gene expression and can survive in the bloodstream. Finding the key genes whose expression are altered in CTCs could help explain the mechanism of tumor metastasis. We searched for genes differentially expressed in CTCs by analyzing four CTCs and primary tumor gene expression datasets in the GEO database. Key genes of clear cell renal cell carcinoma (ccRCC) CTCs were identified. The correlation between key genes and the immune microenvironment of ccRCC was explored. Finally, the CTCs cell model of ccRCC was constructed by in vivo screening method, and the expression of key genes was detected at the cell and tissue levels. A total of 771 DEGs were obtained. Gene enrichment analysis showed that DEGs of CTCs were mainly involved in the regulation of the tumor immune process and tumor cell apoptosis. Finally, we found 2 key genes, MMP9 and TYROBP in ccRCC CTCs. The high expression of these 2 genes predicted a poor prognosis of ccRCC, and the expression levels of these 2 genes were significantly increased in CTCs and ccRCC tissues. Our study suggested that genetic alterations in CTCs contribute to the ability of CTCs to survive in the blood by adapting to the tumor microenvironment. MMP9 and TYROBP are potential therapeutic and prognostic targets for ccRCC.

Recent progress of nanostructure-based enrichment of circulating tumor cells and downstream analysis

The isolation and detection of circulating tumor cells (CTCs) play an important role in early cancer diagnosis and prognosis, providing easy access to identify metastatic cells before clinically detectable metastases. In the past 20 years, according to the heterogeneous expression of CTCs on the surface and their special physical properties (size, morphology, electricity, etc.), a series of in vitro enrichment methods of CTCs have been developed based on microfluidic chip technology, nanomaterials and various nanostructures. In recent years, the in vivo detection of CTCs has attracted considerable attention. Photoacoustic flow cytometry and fluorescence flow cytometry were used to detect CTCs in a noninvasive manner. In addition, flexible magnetic wire and indwelling intravascular non-circulating CTCs isolation system were developed for in vivo CTCs study. In the aspect of downstream analysis, gene analysis and drug sensitivity tests of enriched CTCs were developed based on various existing molecular analysis techniques. All of these studies constitute a complete study of CTCs. Although the existing reviews mainly focus on one aspect of capturing CTCs study, a review that includes the in vivo and in vitro capture and downstream analysis study of CTCs is highly needed. This review focuses on not only the classic work and latest research progress in in vitro capture but also includes the in vivo capture and downstream analysis, discussing the advantages and significance of the different research methods and providing new ideas for solving the heterogeneity and rarity of CTCs.

LncRNA NCK1-AS1-mediated regulatory functions in human diseases

Disease development requires the activation of complex multi-factor processes involving numerous long noncoding RNAs (lncRNAs), which describe non-protein-coding RNAs longer than 200 nucleotides. Emerging evidence indicates that lncRNAs act as essential regulators that perform pivotal roles in the pathogenesis and progression of human diseases. The mechanisms underlying lncRNA involvement in diverse diseases have been extensively explored, and lncRNAs are considered powerful biomarkers for clinical practice. The lncRNA noncatalytic region of tyrosine kinase adaptor protein 1 (NCK1) antisense 1 (NCK1-AS1), also known as NCK1 divergent transcript (NCK1-DT), is encoded on human chromosome 3q22.3 and produces a 27,274-base-long transcript. NCK1-AS1 has increasingly been characterized as a causative agent for multiple diseases. The abnormal expression and involvement of NCK1-AS1 in various biological processes have been associated with several diseases. Further exploration of the mechanisms through which NCK1-AS1 contributes to disease development and progression will provide a foundation for potential clinical applications of NCK1-AS1 in the diagnosis and treatment of various diseases. This review summarizes the current understanding of the various functions and mechanisms through which NCK1-AS1 contributes to various diseases and the clinical application prospects for NCK1-AS1.

Role of Circulating Tumor Cells in Determining Prognosis in Metastatic Breast Cancer

Dinesh Chandra DovalBackground  Circulating tumor cells (CTCs) in the peripheral blood may play a major role in the metastatic spread of breast cancer. This study was conducted to assess the role of CTCs to determine the prognosis in terms of survival in metastatic breast cancer patients. Methods  This prospective study of 36 patients was conducted at the Hospital from April 2016 to May 2018. Details of each patient related to the demographic profile, tumor type, treatment, and follow-up information were recorded. The number of CTCs in the peripheral blood was measured by Celsee PREP 400 sample processing system and Celsee Analyzer imaging station. Results  There was a positive correlation between the number of site of metastasis with number of CTCs ( p -value < 0.001). In the patients with clinical/partial response, a significant reduction in the number of CTCs after 1 month of therapy was observed ( p -value = 0.003). When the number of CTCs at baseline and 6 months were compared with the positron emission tomography response at 6 months, a statistically significant difference in CTCs in patients having partial response after 6 months was observed ( p -value = 0.001). On comparison with the responder groups, a statistically significant reduction in CTCs at baseline and 6 months was observed ( p -value = 0.001). Patients with CTCs less than 5 and more than or equal to 5 after 1 month of treatment had a mean progression-free survival of 11.1 months and 7.5 months ( p -value = 0.04) and a mean overall survival of 11.6 and 9.6 months ( p -value = 0.08), respectively. Conclusion  Assessment of CTCs provides a more quantifiable response than radiographic evaluation and at a much earlier time point and is also a better predictor of survival.

The Protocol of Circulating Tumor Cell Detection

The detection of CTCs is related to the development of tumors and can be used in medical fields such as early diagnosis, postoperative evaluation, monitoring treatment, and predicting disease prognosis. This article focuses on the entire process of CTC detection, including negative enrichment isolation and immunofluorescence in situ hybridization detection.

Liquid biopsy for the assessment of adrenal cancer heterogeneity: where do we stand?

Almost 10 years have passed since the first attempts of liquid biopsy aimed at the characterisation of tumor cells present in the bloodstream from a regular sample of peripheral blood were performed. Liquid biopsy has been used to characterise tumor heterogeneity in various types of solid tumors including adrenocortical carcinoma. The development of molecular biology, genetics, and methodological advances such as digital PCR and next-generation sequencing allowed us to use besides circulating tumor cells a variety of circulating cell-free nucleic acids, DNAs, RNAs and microRNAs secreted by tumors into blood and other body fluids as specific molecular markers. These markers are used for diagnosis, to check tumor development, selecting efficient therapies, therapy monitoring and even possess prognostic power. In adrenocortical carcinoma, there are some studies reporting analysis of circulating tumor cells, circulating cell free DNA and microRNAs for assessing tumor heterogeneity. Among microRNAs, hsa-miR-483-5p seems to be the most important player. Combined with other microRNAs like hsa-miR-195, their expression correlates with recurrence-free survival. Most studies support the applicability of liquid biopsy for assessing temporal tumor heterogeneity (i.e. tumor progression) in adrenocortical cancer. In this mini-review, the available findings of liquid biopsy for assessing tumor heterogeneity in adrenocortical cancer are presented.

Circulating Tumour Cells, Cell Free DNA and Tumour-Educated Platelets as Reliable Prognostic and Management Biomarkers for the Liquid Biopsy in Multiple Myeloma

Simple Summary

Even though the presently employed biomarkers in the detection and management of multiple myeloma are demonstrating encouraging results, the mortality percentage of the malignancy is still elevated. Thus, searching for new diagnostic or prognostic markers is pivotal. Liquid biopsy allows the examination of circulating tumour DNA, cell-free DNA, extracellular RNA, and cell free proteins, which are released into the bloodstream due to the breakdown of tumour cells or exosome delivery. Liquid biopsy can now be applied in clinical practice to diagnose, and monitor multiple myeloma, probably allowing a personalized treatment of the disease.

Abstract

Liquid biopsy is one of the fastest emerging fields in cancer evaluation. Circulating tumour cells and tumour-originated DNA in plasma have become the new targets for their possible employ in tumour diagnosis, and liquid biopsy can define tumour burden without invasive procedures. Multiple Myeloma, one of the most frequent hematologic tumors, has been the target of therapeutic progresses in the last few years. Bone marrow aspirate is the traditional tool for diagnosis, prognosis, and genetic evaluation in multiple myeloma patients. However, this painful procedure presents a relevant drawback for regular disease examination as it requires an invasive practice. Moreover, new data demonstrated that a sole bone marrow aspirate is incapable of expressing the multifaceted multiple myeloma genetic heterogeneity. In this review, we report the emerging usefulness of the assessment of circulating tumour cells, cell-free DNA, extracellular RNA, cell-free proteins, extracellular vesicles, and tumour-educated platelets to evaluate the changing mutational profile of multiple myeloma, as early markers of disease, reliable predictors of prognosis, and as useful tools to perform less invasive monitoring in multiple myeloma.

An exploratory study on the checkout rate of circulating tumor cells and the prediction of efficacy of neoadjuvant therapy and prognosis in patients with HER-2-positive early breast cancer

Background

Neoadjuvant therapy is a standard treatment for patients with large, nonmetastatic breast cancer and may allow breast-conserving surgery after tumor downsizing while decreasing the risk of subsequent relapse. Dynamic changes of circulation tumor cells (CTCs) have a role in predicting treatment efficacy of breast cancer. However, the relationship between CTC enumeration before neoadjuvant therapy and pathologic complete response rate is still uncertain.

Methods

The study was exploratory. A total of 50 breast cancer patients were enrolled in a phase II clinical study of neoadjuvant therapy for HER-2-positive early breast cancer. They were enrolled for blood draws before and after neoadjuvant therapy. We used two methods (CellSearch and TUMORFISH) to detect CTCs. We compared the sensitivity of the two systems and investigated the correlation of the enumeration on baseline CTCs with the diagnosis, prognosis, and efficacy of neoadjuvant therapy of the patients with HER-2-positive early breast cancer. We also explored the dynamic change of CTCs after neoadjuvant therapy.

Results

The sensitivity of TUMORFISHER (27/50) method was significantly higher than that of the CellSearch system (15/50, p=0.008). The CTC numbers detected by the two detection systems were not significantly correlated with lymph node status, clinical stage, ki-67 level and hormone receptor status. Patients with ≥1 CTC before neoadjuvant therapy measured by the TUMORFISHER system had a significant high pCR rate (74.1% vs. 39.1%, p = 0.013); whereas, there was no predictive effect on pCR by CellSearch system (73.3% vs. 51.4%, p = 0.15). Patients with a decrease in CTCs enumeration after neoadjuvant therapy were more likely to achieve pCR than those with no change or increase in CTCs enumeration (87.5% vs 50.0%, p = 0.015) by the TUMORFISHER method. Unfortunately, there was no predictive value of CTCs enumeration for EFS before and after neoadjuvant therapy by two methods.

Conclusions

Our study demonstrates that the new CTCs detection method TUMORFISHER system has a higher checkout rate in early breast cancer than the CellSearch system, and shows the opportunity of CTC enumeration as a novel assistant biomarker to predict the response of neoadjuvant therapy in patients with HER-2-positive early breast cancer.

Circulating tumor cells detected in follow-up predict survival outcomes in tri-modality management of advanced non-metastatic esophageal cancer: a secondary analysis of the QUINTETT randomized trial

Background

Our aim was to establish if presence of circulating tumor cells (CTCs) predicted worse outcome in patients with non-metastatic esophageal cancer undergoing tri-modality therapy.

Methods

We prospectively collected CTC data from patients with operable non-metastatic esophageal cancer from April 2009 to November 2016 enrolled in our QUINTETT esophageal cancer randomized trial (NCT00907543). Patients were randomized to receive either neoadjuvant cisplatin and 5-fluorouracil (5-FU) plus radiotherapy followed by surgical resection (Neoadjuvant) or adjuvant cisplatin, 5-FU, and epirubicin chemotherapy with concurrent extended volume radiotherapy following surgical resection (Adjuvant). CTCs were identified with the CellSearch® system before the initiation of any treatment (surgery or chemoradiotherapy) as well as at 6-, 12-, and 24-months post-treatment. The threshold for CTC positivity was one and the findings were correlated with patient prognosis.

Results

CTC data were available for 74 of 96 patients and identified in 27 patients (36.5%) at a median follow-up of 13.1months (interquartile range:6.8-24.1 months). Detection of CTCs at any follow-up visit was significantly predictive of worse disease-free survival (DFS;hazard ratio [HR]: 2.44; 95% confidence interval [CI]: 1.41-4.24; p=0.002), regional control (HR: 6.18; 95% CI: 1.18-32.35; p=0.031), distant control (HR: 2.93; 95% CI: 1.52-5.65;p=0.001) and overall survival (OS;HR: 2.02; 95% CI: 1.16-3.51; p=0.013). After adjusting for receiving neoadjuvant vs. adjuvant chemoradiotherapy, the presence of CTCs at any follow-up visit remained significantly predictive of worse OS ([HR]:2.02;95% [Cl]:1.16-3.51; p=0.013) and DFS (HR: 2.49;95% Cl: 1.43-4.33; p=0.001). Similarly, any observed increase in CTCs was significantly predictive of worse OS (HR: 3.14; 95% CI: 1.56-6.34; p=0.001) and DFS (HR: 3.34; 95% CI: 1.67-6.69; p<0.001).

Conclusion

The presence of CTCs in patients during follow-up after tri-modality therapy was associated with significantly poorer DFS and OS regardless of timing of chemoradiotherapy.

CircRNA circFOXK2 facilitates oncogenesis in breast cancer via IGF2BP3/miR-370 axis

Metastasis is the leading cause of breast cancer (BC)-related deaths. Circular RNAs (circRNAs) have emerged as essential regulators for cancer progression and metastasis. Therefore, the objective of this study was to investigate the role of circRNAs in BC metastasis and related mechanism. In this study, we established the BC cell line with high or low potential of metastasis. RNA sequencing, migration and invasion assay, Fluorescence in situ hybridization, luciferase report assay, circRNA pulldown, and transmission electron microscopy were performed to elucidate the molecular mechanism. The results showed that circRNA circFOXK2 was significantly increased in BC cells with high metastatic ability, and the upregulation of circFOXK2 was correlated with poor clinicopathological characteristics. Functional experiments demonstrated that overexpression of circFOXK2 promoted migration and invasion of BC cells. Also. circFOXK2 could act with IGF2BP3, an RNA-binding protein, and miR-370 to synergistically promote BC metastasis. Moreover, miR-370 could be transferred through exosomes to enhance the metastatic ability of recipient cells. In conclusion, circFOXK2 functions as a key regulator in BC metastasis, and the role of circFOXK2 on BC metastasis is tightly associated with the involvement of IGF2BP3 and miR-370. CircFOXK2 might serve as a potential biomarker for the diagnosis and treatment of BC.

Circulating tumor cell detection methods in renal cell carcinoma: A systematic review

Circulating tumor cells (CTCs) have a potential role as the missing renal cell carcinoma (RCC) biomarker. However, the available evidence is limited, and detection methods lack standardization, hindering clinical use. We performed a systematic review on CTC enrichment and detection methods, and its role as a biomarker in RCC. Full-text screening identified 54 studies. Reviewed studies showed wide heterogeneity, low evidence level, and high risk of bias. Various CTC detection platforms and molecular markers have been used, but none has proven to be superior. CTC detection and CTC count seem to correlate with staging and survival outcomes, although evidence is inconsistent. CTC research is still in an exploratory phase, particularly in RCC. Further studies are still necessary to achieve a standardization of techniques, molecular markers, CTC definitions, and terminology. This is essential to ascertain the role of CTCs as a biomarker and guide future liquid biopsy research in RCC.

Expression and analysis of PD-L1 in peripheral blood circulating tumor cells of lung cancer

Aim: PD-L1 is an important immune intervention target for lung cancer treatment; however, its clinical significance and biological function in circulating tumor cells (CTCs) of lung cancer need to be explored in depth. Materials & methods: In this study, the CanPatrol method was used to detect three types of CTCs and PD-L1 in 271 lung cancer patients from December 2015 to October 2019. Results: Smoking index, pathological diagnosis and clinical stage are independent influencing factors of PD-L1 expression. The methods that affect the count of CTCs are first-line chemotherapy and targeted therapy; however, there is no difference in the expression of PD-L1 with different treatments. Conclusions: The detection of CTCs and PD-L1 in peripheral blood is helpful for the diagnosis of lung cancer patients.

A DNA logic gate with dual-anchored proximity aptamers for the accurate identification of circulating tumor cells

We have designed a DNA logic gate that can integrate the recognition of multiple biomarkers with signal amplification to perform the accurate and sensitive analysis of circulating tumor cells (CTCs). It also has the potential to analyze rare cells that exist in small amounts but are of great significance (such as stem cells) in the fields of clinical diagnosis and biomedicine.

Future Directions in Diagnosis, Prognosis and Disease Monitoring of Adrenocortical Carcinoma: Novel Non-Invasive Biomarkers

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with frequent metastatic spread and poor prognosis. The disease can occur at any age with unexpected biological behavior. Recent genome-wide studies of ACC have contributed to our understanding of the disease, but diagnosis of ACC remains a challenge, even for multidisciplinary expert teams. Patients with ACC are frequently diagnosed in advanced stages and have limited therapeutic options. Therefore, for earlier diagnosis and better clinical management of adrenocortical carcinoma, specific, sensitive, and minimal invasive markers are urgently needed. Over several decades, great efforts have been made in discovering novel and reliable diagnostic and prognostic biomarkers including microRNAs, steroid profilings, circulating tumor cells, circulating tumor DNAs and radiomics. In this review, we will summarize these novel noninvasive biomarkers and analyze their values for diagnosis, predicting prognosis, and disease monitoring. Current problems and possible future application of these non-invasive biomarkers will also be discussed.

Molecular tracing of prostate cancer lethality

Prostate cancer is diagnosed mostly in men over the age of 50 years, and has favorable 5-year survival rates due to early cancer detection and availability of curative surgical management. However, progression to metastasis and emergence of therapeutic resistance are responsible for the majority of prostate cancer mortalities. Recent advancement in sequencing technologies and computational capabilities have improved the ability to organize and analyze large data, thus enabling the identification of novel biomarkers for survival, metastatic progression and patient prognosis. Large-scale sequencing studies have also uncovered genetic and epigenetic signatures associated with prostate cancer molecular subtypes, supporting the development of personalized targeted-therapies. However, the current state of mainstream prostate cancer management does not take full advantage of the personalized diagnostic and treatment modalities available. This review focuses on interrogating biomarkers of prostate cancer progression, including gene signatures that correspond to the acquisition of tumor lethality and those of predictive and prognostic value in progression to advanced disease, and suggest how we can use our knowledge of biomarkers and molecular subtypes to improve patient treatment and survival outcomes.

Comparative Analysis of Blood and Bone Marrow for the Detection of Circulating and Disseminated Tumor Cells and Their Prognostic and Predictive Value in Esophageal Cancer Patients

Hematogenic tumor cell spread is a key event in metastasis. However, the clinical significance of circulating tumor cells (CTC) in the blood and disseminated tumor cells (DTC) in bone marrow is still not fully understood. Here, the presence of DTC and CTC in esophageal cancer (EC) patients and its correlation with clinical parameters was investigated to evaluate the CTC/DTC prognostic value in EC. This study included 77 EC patients with complete surgical tumor resection. CTC and DTC were analyzed in blood and bone marrow using nested CK20 reverse transcription-nested polymerase chain reaction (RT-PCR) and findings were correlated with clinical data. Twenty-seven of 76 patients (36.5%) showed CK20 positivity in the blood, 19 of 61 patients (31.1%) in bone marrow, and 40 (51.9%) of 77 patients were positive in either blood or bone marrow or both. In multivariate analyses, only the DTC status emerged as independent predictor of overall and tumor specific survival. Our study revealed that, while the presence of CTC in blood is not associated with a worse prognosis, DTC detection in the bone marrow is a highly specific and independent prognostic marker in EC patients. Larger cohort studies could unravel how this finding can be translated into improved therapy management in EC.

Liquid biopsies for multiple myeloma in a time of precision medicine

Multiple myeloma (MM) is a challenging, progressive, and highly heterogeneous hematological malignancy. MM is characterized by multifocal proliferation of neoplastic plasma cells in the bone marrow (BM) and sometimes in extramedullary organs. Despite the availability of novel drugs and the longer median overall survival, some patients survive more than 10 years while others die rapidly. This heterogeneity is mainly driven by biological characteristics of MM cells, including genetic abnormalities. Disease progressions are mainly due to the inability of drugs to overcome refractory disease and inevitable drug-resistant relapse. In clinical practice, a bone marrow biopsy, mostly performed in one site, is still used to access the genetics of MM. However, BM biopsy use is limited by its invasive nature and by often not accurately reflecting the mutational profile of MM. Recent insights into the genetic landscape of MM provide a valuable opportunity to implement precision medicine approaches aiming to enable better patient profiling and selection of targeted therapies. In this review, we explore the use of the emerging field of liquid biopsies in myeloma patients considering current unmet medical needs, such as assessing the dynamic mutational landscape of myeloma, early predictors of treatment response, and a less invasive response monitoring.

Circulating Tumor Cell Counts in Patients With Localized Prostate Cancer Including Those Under Active Surveillance

AIM

To evaluate the clinical efficacy of a circulating tumor cell (CTC) test by comparison between healthy volunteers and patients with localized prostate cancer including those under active surveillance.

MATERIALS AND METHODS

CTC counts in peripheral blood were compared between patients with prostate cancer (n=45) and healthy volunteers (n=17). CTCs were identified based on the expression of epithelial cell adhesion molecule (EpCAM) and counted using a SMART BIOPSY™ SYSTEM.

RESULTS

The number of EpCAM+ cells was significantly higher in patients with cancer than in healthy volunteers. Among the low-risk patients (n=9), two had up-staging and six had up-grading. Among those up-staged, there was one case which was EpCAM⁺ Among those cases up-graded, three were EpCAM⁺ In those with stage T2 tumors, the presence of Gleason pattern 5 was positively correlated with EpCAM positivity (rho=0.59, p<0.001).

CONCLUSION

CTC counts in localized prostate cancer were associated with Gleason pattern 5. Active treatment should be considered for patients with low-risk disease during active surveillance who are found to have EpCAM+ CTCs because of a risk of up-staging and up-grading.

Nanoparticle modification of microfluidic cell separation for cancer cell detection and isolation

We present a nanoparticle surface modification approach to improve the microfluidic performance in detecting cancer cells. Multiple cancer cell lines were included in this work, and the capture ability of the chip with surface modification reached a significant increase.

PIC&RUN: An integrated assay for the detection and retrieval of single viable circulating tumor cells

Circulating tumor cells (CTCs) shed from solid tumors can serve as a minimally invasive liquid biopsy for monitoring disease progression. Because CTCs are rare and heterogeneous, their biological properties need to be investigated at the single cell level, which requires efficient ways to isolate and analyze live single CTCs. Current methods for CTC isolation and identification are either performed on fixed and stained cells or need multiple procedures to isolate pure live CTCs. Here, we used the AccuCyte-RareCyte system to develop a Protocol for Integrated Capture and Retrieval of Ultra-pure single live CTCs using Negative and positive selection (PIC&RUN). The positive selection module of PIC&RUN identifies CTCs based on detection of cancer surface markers and exclusion of immune markers. Combined with a two-step cell picking protocol to retrieve ultrapure single CTCs, the positive selection module is compatible for downstream single cell transcriptomic analysis. The negative selection module of PIC&RUN identifies CTCs based on a live cell dye and the absence of immune markers, allowing retrieval of viable CTCs that are suitable for ex vivo culture. This new assay combines the CTC capture and retrieval in one integrated platform, providing a valuable tool for downstream live CTC analyses.

Screening of Prognosis-Related Genes in Primary Breast Carcinoma Using Genomic Expression Data

This study aimed at exploring the genes that may be related to the prognosis of primary breast cancer (BC) patients. The gene expression microarray data, together with sample survival data were acquired from The Cancer Genome Atlas database. The top 20% genes according to expression value variance were subjected to hierarchical cluster analysis. Bootstrap methods were utilized to assess the stability of cluster. Cox regression was applied to screen genes related to the survival time of patients with BC, and the Beta-Uniform Mixture model was applied to adjust the significance of numerous tests. Further, ingenuity pathway analysis (IPA) was carried out to analyze the functions of the potential prognostic genes. Cluster analysis revealed that there were at least five stable BC subtypes, each with specific gene expression. Further, 42 survival time-associated genes were found (p-value = 0.0006, false discovery rate = 0.2) by Cox regression analysis. According to Gene Ontology (GO) functional annotation, genes in clusters A, B, C, D, and E separately were implicated in cell adhesion cooperation, cell stress response, cell cycle, the assembly of nucleosome and chromosome, and immune regulation. IPA results showed that prognosis-related genes mainly participated in the pathways of cell apoptosis, and cell communication and morphology. Genes such as JAK2, TBP, PTGES3, and RYBP may be promising prognostic biomarkers for BC patients.

Recent advances in microfluidic methods in cancer liquid biopsy

Early cancer detection, its monitoring, and therapeutical prediction are highly valuable, though extremely challenging targets in oncology. Significant progress has been made recently, resulting in a group of devices and techniques that are now capable of successfully detecting, interpreting, and monitoring cancer biomarkers in body fluids. Precise information about malignancies can be obtained from liquid biopsies by isolating and analyzing circulating tumor cells (CTCs) or nucleic acids, tumor-derived vesicles or proteins, and metabolites. The current work provides a general overview of the latest on-chip technological developments for cancer liquid biopsy. Current challenges for their translation and their application in various clinical settings are discussed. Microfluidic solutions for each set of biomarkers are compared, and a global overview of the major trends and ongoing research challenges is given. A detailed analysis of the microfluidic isolation of CTCs with recent efforts that aimed at increasing purity and capture efficiency is provided as well. Although CTCs have been the focus of a vast microfluidic research effort as the key element for obtaining relevant information, important clinical insights can also be achieved from alternative biomarkers, such as classical protein biomarkers, exosomes, or circulating-free nucleic acids. Finally, while most work has been devoted to the analysis of blood-based biomarkers, we highlight the less explored potential of urine as an ideal source of molecular cancer biomarkers for point-of-care lab-on-chip devices.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The Significance of Circulating Tumour Cells in the Clinic

BACKGROUND

Despite the hype about circulating tumour cells (CTCs) in the early 2000s and their potential in the diagnosis of metastasis, in recent years, the hope for personalised cancer management relies more on circulating tumour (ct)DNA that has entered the clinic in a much more efficient way. So far, approved methods for CTCs in the clinic only provide the counting of CTCs, which enables monitoring of the progression of metastatic breast, prostate, and colorectal cancer patients with therapy. Approved methods for ctDNA facilitate the analysis of specific mutations in lung cancer, thereby providing indications for potentially successful treatments. This situation inclined the balance towards molecular analysis in liquid biopsy, leveraged by new technologies and companies providing broader mutation and gene expression analysis towards the early diagnosis of cancer.

STUDY DESIGN

We conducted a search for the studies published to date that provide details about the significance of CTCs in the clinic.

RESULTS

Many studies and clinical trials have demonstrated the potential of CTCs in patient screening, early diagnosis, therapy resistance, and patient prognosis.

CONCLUSIONS

Large multi-centre studies are still needed to formally validate the clinical relevance of CTCs. Meticulous design of the clinical trials is a crucial point to achieve this long-sought objective.

Circulating Tumor Cells Develop Resistance to TRAIL-Induced Apoptosis Through Autophagic Removal of Death Receptor 5: Evidence from an In Vitro Model

Circulating tumor cells (CTCs) in the peripheral blood are the precursors to distant metastasis but the underlying mechanisms are poorly understood. This study aims at understanding the molecular features within CTCs, in relation to their metastatic potential. Using in vitro CTC models, in which breast cancer cell lines were cultured in non-adherent conditions simulating the microenvironment in the blood stream, we found that the suspension culture resulted in resistance to TNF-related apoptosis inducing ligand (TRAIL)-mediated cell death. Such a resistance was directly correlated with a reduction in surface and total levels of DR5 protein. In the non-adherent state, the cells underwent a rapid autophagic flux, characterized by an accumulation of autophagosome organelles. Notably, DR5 was translocated to the autophagosomes and underwent a lysosomal degradation. Our data suggest that CTCs may evade the TNF cytokine-mediated immune surveillance through a downregulation of the death receptor (DR) expression. The data warrants further studies in cancer patients to find the status of DRs and other molecular features within primary CTCs, in relation to disease progression or chemoresistance.

Circulating Tumor Cells with Stem-Like Phenotypes for Diagnosis, Prognosis, and Therapeutic Response Evaluation in Hepatocellular Carcinoma

Background: In the present study, we assessed the clinical value of circulating tumor cells (CTC) with stem-like phenotypes for diagnosis, prognosis, and surveillance in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) by an optimized qPCR-based detection platform.Methods: Differing subsets of CTCs were investigated, and a multimarker diagnostic CTC panel was constructed in a multicenter patient study with independent validation (total n = 1,006), including healthy individuals and patients with chronic hepatitis B infection (CHB), liver cirrhosis (LC), benign hepatic lesion (BHL), and HBV-related HCC, with area under the receiver operating characteristic curve (AUC-ROC) reflecting diagnostic accuracy. The role of the CTC panel in treatment response surveillance and its prognostic significance were further investigated.Results: The AUC of the CTC panel was 0.88 in the training set [sensitivity = 72.5%, specificity = 95.0%, positive predictive value (PPV) = 92.4, negative predictive value (NPV) = 77.8] and 0.93 in the validation set (sensitivity = 82.1%, specificity = 94.2%, PPV = 89.9, NPV = 89.3). This panel performed equally well in detecting early-stage and α-fetoprotein-negative HCC, as well as differentiating HCC from CHB, LC, and BHL. The CTC load was decreased significantly after tumor resection, and patients with persistently high CTC load showed a propensity of tumor recurrence after surgery. The prognostic significance of the CTC panel in predicting tumor recurrence was further confirmed [training: HR = 2.692; 95% confidence interval (CI), 1.617-4.483; P < 0.001; and validation: HR = 3.127; 95% CI, 1.360-7.190; P = 0.007].Conclusions: Our CTC panel showed high sensitivity and specificity in HCC diagnosis and could be a real-time parameter for risk prediction and treatment monitoring, enabling early decision-making to tailor effective antitumor strategies. Clin Cancer Res; 24(9); 2203-13. ©2018 AACR.

Platforms for Single-Cell Collection and Analysis

Single-cell analysis has become an established method to study cell heterogeneity and for rare cell characterization. Despite the high cost and technical constraints, applications are increasing every year in all fields of biology. Following the trend, there is a tremendous development of tools for single-cell analysis, especially in the RNA sequencing field. Every improvement increases sensitivity and throughput. Collecting a large amount of data also stimulates the development of new approaches for bioinformatic analysis and interpretation. However, the essential requirement for any analysis is the collection of single cells of high quality. The single-cell isolation must be fast, effective, and gentle to maintain the native expression profiles. Classical methods for single-cell isolation are micromanipulation, microdissection, and fluorescence-activated cell sorting (FACS). In the last decade several new and highly efficient approaches have been developed, which not just supplement but may fully replace the traditional ones. These new techniques are based on microfluidic chips, droplets, micro-well plates, and automatic collection of cells using capillaries, magnets, an electric field, or a punching probe. In this review we summarize the current methods and developments in this field. We discuss the advantages of the different commercially available platforms and their applicability, and also provide remarks on future developments.

Cytometric Profiling of CD133+ Cells in Human Colon Carcinoma Cell Lines Identifies a Common core Phenotype and Cell Type-specific Mosaics

In colorectal cancer, CD133+ cells from fresh biopsies proved to be more tumorigenic than their CD133– counterparts. Nevertheless, the function of CD133 protein in tumorigenic cells seems only marginal. Moreover, CD133 expression alone is insufficient to isolate true cancer stem cells, since only 1 out of 262 CD133+ cells actually displays stem-cell capacity. Thus, new markers for colorectal cancer stem cells are needed. Here, we show the extensive characterization of CD133+ cells in 5 different colon carcinoma continuous cell lines (HT29, HCT116, Caco2, GEO and LS174T), each representing a different maturation level of colorectal cancer cells. Markers associated with stemness, tumorigenesis and metastatic potential were selected. We identified 6 molecules consistently present on CD133+ cells: CD9, CD29, CD49b, CD59, CD151, and CD326. By contrast, CD24, CD26, CD54, CD66c, CD81, CD90, CD99, CD112, CD164, CD166, and CD200 showed a discontinuous behavior, which led us to identify cell type-specific surface antigen mosaics. Finally, some antigens, e.g. CD227, indicated the possibility of classifying the CD133+ cells into 2 subsets likely exhibiting specific features. This study reports, for the first time, an extended characterization of the CD133+ cells in colon carcinoma cell lines and provides a “dictionary” of antigens to be used in colorectal cancer research.

Cancer Stem Cells in Metastasis Therapy

Tumors consists of subpopulation of cells in which each subtype has contributes to tumor progression. Specifically one subtype known as cancer stem cells are associated with the initiation, progression, resistance to conventional therapies and metastasis. Metastasis is leading cause of cancer related deaths. Overall it is important to consider cancer as a whole in which a mutated cell proliferating indefinitely and forming its hierarchy consisting of subgroups with different molecular signatures. To be able to target this disease we need to evaluate every step including initiation, progression, survival, angiogenesis and finally migration and repopulation. Cancer stem cells do play vital roles in each step however when metastasis can be stopped or eliminated we talk about saving a life or improving its quality. Considering how deeply these cancer stem like cells affect the tumor life and metastasis it is crucial to develop effective strategies against them. Metastatic cascade can also be directed by membrane derived vesicles specifically exosomes. Several studies show the role of exosomes in mediating cellular migration and pre-metastatic niche formation. During this chapter we wanted to explain in detail how the metastasis occur in tumor and how cancer stem cells contribute into the development of metastatic cascade and possibly suggest therapeutic approaches against cancer stem cells.

High expression of carcinoembryonic antigen and telomerase reverse transcriptase in circulating tumor cells is associated with poor clinical response to the immune checkpoint inhibitor nivolumab

The present study aimed to enrich circulating tumor cells (CTCs) from blood samples using a new size-sorting CTC chip. The present study also set out to identify a blood sensitivity marker for the immune checkpoint inhibitor nivolumab in patients with advanced, pre-treatment lung cancer. The CTC sorting efficacy of the chip was investigated and the large cell fraction of blood samples from 15 patients with pre-treatment lung cancer who were later administered nivolumab were purified. The expression levels of carcinoembryonic antigen (CEA), human Telomerase Reverse Transcriptase (hTERT), cytokeratin19 (CK19), and programmed death ligand-1 (PD-L1) were investigated to clarify the association between these CTC markers and the clinical response to nivolumab. The CTC chip effectively enriched cells from lung cancer cell line PC-9. The large cell fraction had a high expression of CEA and hTERT, with the former being significantly associated with the clinical response to nivolumab. The expression of CEA and hTERT in CTCs derived from the blood of a patient with lung cancer were also validated. The evaluation of CEA and possibly hTERT in CTCs collected by the CTC chip may represent a promising predictive blood marker for sensitivity to nivolumab. To the best of our knowledge this is the first report to describe the predictive CTC marker for nivolumab in pre-treatment patients.

Krukenberg tumors: Seed, route and soil

The aim of this narrative review was to summarize the current evidence on Krukenberg tumors (KTs), addressing what is known on their natural history and their impact on the clinical prognosis and which are the most appropriate management strategies to treat this condition. A literature search was conducted on Pubmed up to December 2016, selecting the most relevant studies on the basis of the scope of the review. KTs are ovarian metastases from primary signet-ring cell carcinomas., characterized by the presence of a sarcoma-like stroma. They have three possible routes of diffusion (lymphatic, peritoneal and hematogenous), but the preferential one is still unclear. Prognosis is dismal. When KTs are encountered in the clinical practice, it is reasonable to offer surgical resection to young, fit patients with limited disease. Palliative surgery should be considered for all patients with symptomatic disease. Further studies should clarify the clinicopathologic characteristics of KTs, their main routes of diffusion, and the possible role of prophylactic oophorectomy, lymphadenectomy and intraperitoneal chemotherapy. Molecular and transitional research should parallel the clinical one to help understanding the natural history of signet-ring cell carcinomas.

Current Status and Future Prospects of Biomarkers in the Diagnosis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) has one of the highest death rates of any cancer in the world, and its incidence is increasing worldwide. Early-stage diagnosis of HCC is thus crucial for medical treatment. Detection of tumor biomarkers is one of the main methods for the early diagnosis of HCC. At present, α-fetoprotein (AFP) is the most practical serum biomarker for HCC diagnosis. However, the diagnostic accuracy of HCC with serum AFP exhibits both sensitivity and specificity far below satisfaction, especially with small sizes of HCC. As a result, the discovery of new biomarkers and/or their combination to enhance both the sensitivity and specificity for laboratory diagnosis of HCC is a crucial goal. With the development of new technology and advances in research, a number of new and specific biomarkers of HCC have been discovered. These biomarkers and their applications for the diagnosis, treatment monitoring and prognosis prediction of HCC, are reviewed in this article.

Poor Prognosis Indicated by Venous Circulating Tumor Cell Clusters in Early-Stage Lung Cancers

Early detection of metastasis can be aided by circulating tumor cells (CTC), which also show potential to predict early relapse. Because of the limited CTC numbers in peripheral blood in early stages, we investigated CTCs in pulmonary vein blood accessed during surgical resection of tumors. Pulmonary vein (PV) and peripheral vein (Pe) blood specimens from patients with lung cancer were drawn during the perioperative period and assessed for CTC burden using a microfluidic device. From 108 blood samples analyzed from 36 patients, PV had significantly higher number of CTCs compared with preoperative Pe (P < 0.0001) and intraoperative Pe (P < 0.001) blood. CTC clusters with large number of CTCs were observed in 50% of patients, with PV often revealing larger clusters. Long-term surveillance indicated that presence of clusters in preoperative Pe blood predicted a trend toward poor prognosis. Gene expression analysis by RT-qPCR revealed enrichment of p53 signaling and extracellular matrix involvement in PV and Pe samples. Ki67 expression was detected in 62.5% of PV samples and 59.2% of Pe samples, with the majority (72.7%) of patients positive for Ki67 expression in PV having single CTCs as opposed to clusters. Gene ontology analysis revealed enrichment of cell migration and immune-related pathways in CTC clusters, suggesting survival advantage of clusters in circulation. Clusters display characteristics of therapeutic resistance, indicating the aggressive nature of these cells. Thus, CTCs isolated from early stages of lung cancer are predictive of poor prognosis and can be interrogated to determine biomarkers predictive of recurrence. Cancer Res; 77(18); 5194-206. ©2017 AACR.

CTC-mRNA (AR-V7) Analysis from Blood Samples-Impact of Blood Collection Tube and Storage Time

Circulating tumour cells (CTCs) are an emerging resource for monitoring cancer biomarkers. New technologies for CTC isolation and biomarker detection are increasingly sensitive, however, the ideal blood storage conditions to preserve CTC-specific mRNA biomarkers remains undetermined. Here we tested the preservation of tumour cells and CTC-mRNA over time in common anticoagulant ethylene-diamine-tetra-acetic acid (EDTA) and acid citrate dextrose solution B (Citrate) blood tubes compared to preservative-containing blood tubes. Blood samples spiked with prostate cancer cells were processed after 0, 24, 30, and 48 h storage at room temperature. The tumour cell isolation efficiency and the mRNA levels of the prostate cancer biomarkers androgen receptor variant 7 (AR-V7) and total AR, as well as epithelial cell adhesion molecule (EpCAM) were measured. Spiked cells were recovered across all storage tube types and times. Surprisingly, tumour mRNA biomarkers were readily detectable after 48 h storage in EDTA and Citrate tubes, but not in preservative-containing tubes. Notably, AR-V7 expression was detected in prostate cancer patient blood samples after 48 h storage in EDTA tubes at room temperature. This important finding presents opportunities for measuring AR-V7 expression from clinical trial patient samples processed within 48 h-a much more feasible timeframe compared to previous recommendations.

PCR-based amplification of circulating RNAs as prognostic and predictive biomarkers - Focus on neuroblastoma

Metastatic disease is a major challenge for cancer cure, haematogenous spread and subsequent growth of tumour cells at distant sites being the cause of most cancer deaths. Molecular characterization and detection of the tumour cells responsible for haematogenous spread may increase understanding of the biology of metastasis, help improve patient management and allow evaluation of novel treatments to prevent and eradicate this disease. The bone marrow is a common site to which tumour cells metastasize, from which they may re-circulate to other organs with a favourable microenvironment for growth. The detection of tumour cells in blood suggests one route for metastasis, and provides an accessible, minimally invasive liquid sample through which it may be possible to monitor and detect minimal disease and early signs of metastasis. Significant improvements in the sensitivity and specificity of tumour cell detection have been made, such that it is now possible to unambiguously detect a single tumour cell in over 10 million normal cells. However, the clinical impact of such low level disease and how to interpret the natural variation that can arise from sequential sampling of bone marrow aspirates and blood is currently largely unknown. This commentary will focus on the technical advancements and application of reverse transcriptase polymerase chain reaction to detect cancer mRNAs in bone marrow and blood, and discuss the potential clinical impact of this test in neuroblastoma.

Clinical significance of circulating tumor cells in blood from patients with gastric cancer

Circulating tumor cells (CTC) have been focused on as a target for detecting occult tumors, predicting therapeutic responses and prognoses, and monitoring postoperative recurrence in the clinical management of patients with various malignancies, including gastric cancer. Recent advances in molecular diagnostic tools have contributed to high sensitivity and specificity for the detection of CTC. A conspicuous disparity exists in the incidence of CTC among studies. However, a close relationship has been reported between positivity for CTC and well-known prognostic clinicopathological factors including depth of tumor invasion, lymph node metastasis, stage, and lymphatic and venous invasion in patients with gastric cancer. According to most studies published on the clinical impact of CTC, the presence of CTC negatively affects the prognosis of patients with gastric cancer. Moreover, the study of CTC based on a meta-analysis demonstrated their importance as a poor prognostic indicator. In clinical management, pre- and post-therapeutic monitoring of CTC using liquid biopsy may be useful for early detection of subclinical patients or disease recurrence, prediction of tumor progression, and administrative control of adjuvant chemotherapy. Although their functional properties remain unclear, molecular profiling of CTC may contribute to the development of personalized treatment that effectively inhibits tumor progression in patients with advanced gastric cancer. We herein review the clinical significance of CTC as a promising blood marker and therapeutic target in patients with gastric cancer.

Microfluidics cell sample preparation for analysis: Advances in efficient cell enrichment and precise single cell capture

Single cell analysis has received increasing attention recently in both academia and clinics, and there is an urgent need for effective upstream cell sample preparation. Two extremely challenging tasks in cell sample preparation-high-efficiency cell enrichment and precise single cell capture-have now entered into an era full of exciting technological advances, which are mostly enabled by microfluidics. In this review, we summarize the category of technologies that provide new solutions and creative insights into the two tasks of cell manipulation, with a focus on the latest development in the recent five years by highlighting the representative works. By doing so, we aim both to outline the framework and to showcase example applications of each task. In most cases for cell enrichment, we take circulating tumor cells (CTCs) as the target cells because of their research and clinical importance in cancer. For single cell capture, we review related technologies for many kinds of target cells because the technologies are supposed to be more universal to all cells rather than CTCs. Most of the mentioned technologies can be used for both cell enrichment and precise single cell capture. Each technology has its own advantages and specific challenges, which provide opportunities for researchers in their own area. Overall, these technologies have shown great promise and now evolve into real clinical applications.

Vertical Magnetic Separation of Circulating Tumor Cells for Somatic Genomic-Alteration Analysis in Lung Cancer Patients

Efficient isolation and genetic analysis of circulating tumor cells (CTCs) from cancer patients’ blood is a critical step for clinical applications using CTCs. Here, we report a novel CTC-isolation method and subsequent genetic analysis. CTCs from the blood were complexed with magnetic beads coated with antibodies against the epithelial cell adhesion molecule (EpCAM) and separated vertically on a density-gradient medium in a modified well-plate. The recovery rate of model CTCs was reasonable and the cell purity was enhanced dramatically when compared to those parameters obtained using a conventional magnetic isolation method. CTCs were recovered from an increased number of patient samples using our magnetic system vs. the FDA-approved CellSearch system (100% vs. 33%, respectively). In 8 of 13 cases, targeted deep sequencing analysis of CTCs revealed private point mutations present in CTCs but not in matched tumor samples and white blood cells (WBCs), which was also validated by droplet digital PCR. Copy-number alterations in CTCs were also observed in the corresponding tumor tissues for some patients. In this report, we showed that CTCs isolated by the EpCAM-based method had complex and diverse genetic features that were similar to those of tumor samples in some, but not all, cases.

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.

Minimal residual disease in breast cancer: an overview of circulating and disseminated tumour cells

Within the field of cancer research, focus on the study of minimal residual disease (MRD) in the context of carcinoma has grown exponentially over the past several years. MRD encompasses circulating tumour cells (CTCs)—cancer cells on the move via the circulatory or lymphatic system, disseminated tumour cells (DTCs)—cancer cells which have escaped into a distant site (most studies have focused on bone marrow), and resistant cancer cells surviving therapy—be they local or distant, all of which may ultimately give rise to local relapse or overt metastasis. Initial studies simply recorded the presence and number of CTCs and DTCs; however recent advances are allowing assessment of the relationship between their persistence, patient prognosis and the biological properties of MRD, leading to a better understanding of the metastatic process. Technological developments for the isolation and analysis of circulating and disseminated tumour cells continue to emerge, creating new opportunities to monitor disease progression and perhaps alter disease outcome. This review outlines our knowledge to date on both measurement and categorisation of MRD in the form of CTCs and DTCs with respect to how this relates to cancer outcomes, and the hurdles and future of research into both CTCs and DTCs.