Recent Progress in Enhanced Cancer Diagnosis, Prognosis, and Monitoring Using a Combined Analysis of the Number of Circulating Tumor Cells (CTCs) and Other Clinical Parameters

Analysis of circulating tumor cells (CTCs) holds promise to diagnose cancer or monitor its development. Among the methods, counting CTC numbers in blood samples could be the simplest way to implement it. Nevertheless, its clinical utility has not yet been fully accepted. The reasons could be due to the rarity and heterogeneity of CTCs in blood samples that could lead to misleading results from assays only based on single CTC counts. To address this issue, a feasible direction is to combine the CTC counts with other clinical data for analysis. Recent studies have demonstrated the use of this new strategy for early detection and prognosis evaluation of cancers, or even for the distinguishment of cancers with different stages. Overall, this approach could pave a new path to improve the technical problems in the clinical applications of CTC counting techniques. In this review, the information relevant to CTCs, including their characteristics, clinical use of CTC counting, and technologies for CTC enrichment, were first introduced. This was followed by discussing the challenges and new perspectives of CTC counting techniques for clinical applications. Finally, the advantages and the recent progress in combining CTC counts with other clinical parameters for clinical applications have been discussed.

New advances in circulating tumor cell‑mediated metastasis of breast cancer (Review)

Breast cancer stands as the most prevalent form of cancer affecting women, with metastasis serving as a leading cause of mortality among patients with breast cancer. Gaining a comprehensive understanding of the metastatic mechanism in breast cancer is essential for early detection and precision treatment of the disease. Circulating tumor cells (CTCs) play a vital role in this context, representing cancer cells that detach from tumor tissues and enter the bloodstream of cancer patients. These cells travel in the blood circulation as single cells or clusters. Recent research has shed light on the enhanced metastatic potential of CTC clusters compared to single CTCs, despite their limited occurrence. The aim of the present review was to explore recent findings on CTCs with a particular focus on the clustering phenomenon of CTCs observed in breast cancer. Additionally, the present review delved into the comparison between single CTCs and CTC clusters regarding their implications for the treatment and prognosis of patients diagnosed with metastatic breast cancer. By examining the role and mechanisms of CTCs in breast cancer metastasis, the present review provided an improved understanding of CTCs and their significance in early detection of breast cancer metastasis through peripheral blood analysis. Moreover, it contributed to the comprehension of cancer prognosis and prediction by highlighting the implications of CTCs in these aspects. Ultimately, the present study seeks to advance knowledge in the field and pave the way for improved approaches to breast cancer management.

Novel method for highly multiplexed gene expression profiling of circulating tumor cells (CTCs) captured from the blood of women with metastatic breast cancer

BACKGROUND

Enumeration of circulating tumor cells (CTCs) has proven clinical significance for monitoring patients with metastatic cancers. Multiplexed gene expression profiling of CTCs is a potential tool for assessing disease status and monitoring treatment response. The Parsortix^® technology enables the capture and harvest of CTCs from blood based on cell size and deformability. The HyCEAD^™ (Hybrid Capture Enrichment Amplification and Detection) assay enables simultaneous amplification of short amplicons for up to 100 mRNA targets, and the Ziplex^™ instrument quantifies the amplicons for highly sensitive gene expression profiling down to single cell levels. The aim of the study was to functionally assess this system.

METHODS

The HyCEAD/Ziplex platform was used to quantify the expression levels for 72 genes using as little as 20 pg of total RNA or a single cultured tumor cell. Assay performance was evaluated using cells or total RNA spiked into Parsortix harvests of healthy donor blood. The assay was also evaluated using total RNA obtained from Parsortix harvests of blood from metastatic breast cancer (MBC) patients or healthy volunteers (HVs).

RESULTS

Using genes with low expression in WBC RNA and/or in unspiked Parsortix harvests from HVs, the assay distinguished between the different breast cancer and ovarian cancer cell lines with as little as 20 pg of total RNA (equivalent to a single cell) in the presence of 1 ng of WBC RNA. Single cultured cells spiked into Parsortix harvests from 10 mL of HV blood were also detected and distinguished from each other. CVs from repeatability experiments were less than 20%. Hierarchical clustering of clinical samples differentiated most MBC patients from HVs.

CONCLUSION

HyCEAD/Ziplex provided sensitive quantification of expression of 72 genes from 20 pg of total RNA from cultured tumor cell lines or from single cultured tumor cells spiked into lysates from Parsortix harvests of HV blood. The HyCEAD/Ziplex platform enables the quantification of selected genes in the presence of residual nucleated blood cells in Parsortix harvests. The HyCEAD/Ziplex platform is an effective tool for multiplexed molecular characterization of mRNA in small numbers of tumor cells harvested from blood.

Signatures of Breast Cancer Progression in the Blood: What Could Be Learned from Circulating Tumor Cell Transcriptomes

Gene expression profiling has revolutionized our understanding of cancer biology, showing an unprecedented ability to impact patient management especially in breast cancer. The vast majority of breast cancer gene expression signatures derive from the analysis of the tumor bulk, an experimental approach that limits the possibility to dissect breast cancer heterogeneity thoroughly and might miss the message hidden in biologically and clinically relevant cell populations. During disease progression or upon selective pressures, cancer cells undergo continuous transcriptional changes, which inevitably affect tumor heterogeneity, response to therapy and tendency to disseminate. Therefore, metastasis-associated signatures and transcriptome-wide gene expression measurement at single-cell resolution hold great promise for the future of breast cancer clinical care. Seen from this perspective, transcriptomics of circulating tumor cells (CTCs) represent an attractive opportunity to bridge the knowledge gap and develop novel biomarkers. This review summarizes the current state-of-the-science on CTC gene expression analysis in breast cancer, addresses technical and clinical issues related to the application of CTC-derived signatures, and discusses potential research directions.

Circulating tumor cells and cell-free tumor DNA analyses in urothelial cancer using the LiquidBiopsy platform

Background

Emerging data suggested that liquid biopsy such as detection of circulating tumor cells (CTCs) and cell-free tumor DNA analysis augments the management of patients with urothelial cancer (UC). We presented our pilot experience of liquid biopsy using the Ion Torrent platform to detect CTCs and genomic alterations in UC.

Materials and methods

Blood or urine samples from 16 patients were subjected to CTC and plasma/urine cell-free tumor DNA isolation for next generation sequencing (NGS) using the Ion S5 system to detect mutations among 50 oncogenes on the Ion AmpliSeq Cancer Hotspot Panel.

Results

The Ion Torrent platform detected a higher number of CTCs than those in previous studies using the CellSearch^TM system. Overall, mutations were detected in 13/16 (81.3%) patients with a median number of 18 (range 12-25). NGS isolated 17 hotspot mutations from 11 genes and 41 novel genomic alterations from 24 genes, some of which are supposed to be clinically actionable.

Conclusions

The Ion Torrent platform efficiently detected CTCs compared with previous reports. NGS with the present system also allowed for detection of gene alterations which are likely to be therapeutic targets and provided an attractive tool to guide personalized therapy for patients with advanced UC.

Binding blockade between TLN1 and integrin β1 represses triple-negative breast cancer

Background:

Integrin family are known as key gears in focal adhesion for triple-negative breast cancer (TNBC) metastasis. However, the integrin independent factor TLN1 remains vague in TNBC.

Methods:

Bioinformatics analysis was performed based on TCGA database and Shengjing Hospital cohort. Western blot and RT-PCR were used to detect the expression of TLN1 and integrin pathway in cells. A small-molecule C67399 was screened for blocking TLN1 and integrin β1 through a novel computational screening approach by targeting the protein-protein binding interface. Drug pharmacodynamics were determined through xenograft assay.

Results:

Upregulation of TLN1 in TNBC samples correlates with metastasis and worse prognosis. Silencing TLN1 in TNBC cells significantly attenuated the migration of tumour cells through interfering the dynamic formation of focal adhesion with integrin β1, thus regulating FAK-AKT signal pathway and epithelial-mesenchymal transformation. Targeting the binding between TLN1 and integrin β1 by C67399 could repress metastasis of TNBC.

Conclusions:

TLN1 overexpression contributes to TNBC metastasis and C67399 targeting TLN1 may hold promise for TNBC treatment.

Funding:

This study was supported by grants from the National Natural Science Foundation of China (No. 81872159, 81902607, 81874301), Liaoning Colleges Innovative Talent Support Program (Name: Cancer Stem Cell Origin and Biological Behaviour), Outstanding Scientific Fund of Shengjing Hospital (201803), and Outstanding Young Scholars of Liaoning Province (2019-YQ-10).

Detection and clinical significance of circulating tumor cells in colorectal cancer

Histopathological examination (biopsy) is the "gold standard" for the diagnosis of colorectal cancer (CRC). However, biopsy is an invasive method, and due to the temporal and spatial heterogeneity of the tumor, a single biopsy cannot reveal the comprehensive biological characteristics and dynamic changes of the tumor. Therefore, there is a need for new biomarkers to improve CRC diagnosis and to monitor and treat CRC patients. Numerous studies have shown that "liquid biopsy" is a promising minimally invasive method for early CRC detection. A liquid biopsy mainly samples circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), microRNA (miRNA) and extracellular vesicles (EVs). CTCs are malignant cells that are shed from the primary tumors and/or metastases into the peripheral circulation. CTCs carry information on both primary tumors and metastases that can reflect dynamic changes in tumors in a timely manner. As a promising biomarker, CTCs can be used for early disease detection, treatment response and disease progression evaluation, disease mechanism elucidation, and therapeutic target identification for drug development. This review will discuss currently available technologies for plasma CTC isolation and detection, their utility in the management of CRC patients and future research directions.

Functional Genomic Analysis of Breast Cancer Metastasis: Implications for Diagnosis and Therapy

Simple Summary

Metastasis remains the greatest cause of fatalities in breast cancer patients world-wide. The process of metastases is highly complex, and the current research efforts in this area are still rather fragmented. The revolution of genomic profiling methods to analyze samples from human and animal models dramatically improved our understanding of breast cancer metastasis. This article summarizes the recent breakthroughs in genomic analyses of breast cancer metastasis and discusses their implications for prognostic and therapeutic applications.

Abstract

Breast cancer (BC) is one of the most diagnosed cancers worldwide and is the second cause of cancer related death in women. The most frequent cause of BC-related deaths, like many cancers, is metastasis. However, metastasis is a complicated and poorly understood process for which there is a shortage of accurate prognostic indicators and effective treatments. With the rapid and ever-evolving development and application of genomic sequencing technologies, many novel molecules were identified that play previously unappreciated and important roles in the various stages of metastasis. In this review, we summarize current advancements in the functional genomic analysis of BC metastasis and discuss about the potential prognostic and therapeutic implications from the recent genomic findings.

Prospective Evaluation of a Circulating Tumor Cell Sensitivity Profile to Predict Response to Cisplatin Chemotherapy in Metastatic Breast Cancer Patients

Background

Cisplatin (cDDP) has regained interest for metastatic breast cancer (MBC) patients, given the platinum sensitivity in subtypes and better manageable toxicity. Here, the primary aim was to determine whether molecular characteristics of circulating tumor cells (CTCs) could identify patients responding to cDDP and to describe the outcomes to cDDP monotherapy in a large group of MBC patients pretreated with anthracycline- and taxane-based treatments.

Methods

Based on cell line data, a CTC-cDDP-sensitivity profile was generated. Applying an A’Herns single-stage phase II design, further investigation was considered worthwhile if 5/10 patients with a favorable profile responded to cDDP. Patients received 70mg/m² cDDP every three weeks, CTCs were enumerated and the CTC-cDDP-sensitivity profile was determined. In total, 65 heavily pretreated MBC patients (77% received ≥2 lines of previous chemotherapy for MBC) were eligible for the per-protocol analysis. Primary endpoint was response rate, secondary endpoints included best observed response, progression-free survival (PFS) and overall survival (OS).

Results

The best observed response during cDDP therapy was a partial response in 7% and stable disease in 56% of the patients. None of the patients with a favorable CTC-cDDP-sensitivity profile had a response. The median baseline CTC count was 8 (range 0-3254). Patients with <5 CTCs had a better PFS and OS than patients with ≥5 CTCs (median PFS 4.5 months (95%CI 2.38-6.62) vs. 2.1 months [(95%CI 1.34-2.80)(p=0.009)] and median OS 13.1 months (95%CI 9.89-16.33) vs. 5.6 months [(95%CI 3.60-7.64)(p=0.003)]. No other factors than CTC count were associated with outcome to cDDP therapy, including triple-negative breast cancer versus ER-positive tumors.

Conclusions

The CTC-cDDP-sensitivity profile was unable to select patients responding to cDDP monotherapy. In an unselected group of heavily pretreated MBC patients, cDDP yields outcomes comparable to other chemotherapeutic regimens for heavily pretreated MBC patients. CTC count was the only factor associated with outcome in these patients.

Clinical Trial Registration

(https://www.trialregister.nl/trial/3885, identifier NTR4046)

Genetic Heterogeneity of Single Circulating Tumour Cells in Colorectal Carcinoma

The aim of the present study was to isolate and investigate the genetic heterogeneities in single circulating tumour cells (CTCs) from patients with colorectal carcinoma (CRC). Twenty-eight single CTCs were collected from eight patients with CRC using a negative immunomagnetic enrichment method. After validation with glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene expression in 3 colon cancer cell lines, a panel of 19 genes were used to analyse the single CTCs (n = 28), primary colorectal carcinoma tissues (n = 8) and colon carcinoma cells (n = 6) using real-time qPCR. Genetic heterogeneities were assessed by comparing gene expression profiles of single CTCs from the different patients and in the same patient, respectively. Genetic profiling of the single CTCs showed extensive heterogeneities of the selected genes among the CTCs. Hierarchical clustering analyses exhibited two clusters of CTCs with differentially expressed genes, which highlighted different modifications from the primary carcinomas. Further, the genetic heterogeneities were observed between different patients or in the same patient. Finally, AKT1 expression was significantly (p = 0.0129) higher in single CTCs from CRC of advanced pathological stages (III or IV) CRC than in CTCs from CRC of early stages (I or II). Our findings suggest that single-cell genetic analysis can monitor the genetic heterogeneities and guide the personalised therapeutic targets in clinical sectors.

Exploration of Circulating Tumour Cell (CTC) Biology: A Paradigm Shift in Liquid Biopsy

Circulating tumour cells (CTCs), are disseminated tumour cells found in the blood in solid tumour malignancies. Identification of CTCs act as emerging tools in the field of the Liquid Biopsy. Majority of the studies focused on detection and enumeration of CTCs due to technological challenges those results from the rarity of CTCs in the blood. Enumeration of CTCs has already proven their value as prognostic as well as predictive biomarkers for disease prognosis. However, recent advances in technology permitted to study the molecular and functional features of CTCs and these features have the potential to change the diagnostic, prognostic and predictive landscape in oncology. In this review, we summarize the paradigm shift in the field of liquid biopsy-based cancer diagnostics using CTC isolation and detection. We have discussed recent advances in the technologies for molecular characterization of CTCs which have aided a shift from CTC enumeration to an in-depth analysis of the CTC genome, transcriptomes, proteins, epigenomes along with various functional features. Finally, as a prognosticating strategy, the potentials of CTCs as a tool of liquid biopsy to predict micrometastasis, monitor prognosis and how to use them as an additional tool for cancer staging has been discussed.

Circulating tumor cells detection in tumor draining vein of breast cancer patients

Circulating tumor cells (CTCs) in tumor draining vein blood (DB) are potential sources for liquid biopsy. However, the identification of CTCs in DB of breast cancer has not been attempted. In this study, we investigated the feasibility of CTC detection in DB of breast cancer patients using a newly developed filtration-based microfluidic CTC detection device. Samples of peripheral vein blood (PB) and DB drawn from the lateral thoracic vein of the resected breast tissue were collected during the perioperative period. We investigated 41 breast cancer patients who underwent breast surgery with axillary lymph node dissection. DB was successfully collected in 36 patients (87.8%), with a mean amount of 0.85 ml. CTCs were detected in 58.3% of PB samples and 80.6% of DB samples. DB had significant higher number of CTCs compared with PB (p < 0.001). CTCs were detected in 75.0% of DB samples and 50.0% of PB samples from patients achieving pathological complete response after neoadjuvant chemotherapy. These results suggest that abundant CTCs are released into the DB of breast cancer patients, indicating that CTCs in DB would be alternative sources for liquid biopsy and potential indicators for monitoring of treatment response and prognosis in breast cancer patients.

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

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

PIK3CA hotspot mutations in circulating tumor cells and paired circulating tumor DNA in breast cancer: a direct comparison study

Liquid biopsy analysis, mainly based on circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), provides an extremely powerful tool for the molecular profiling of cancer patients in real time. In this study, we directly compared PIK3CA hotspot mutations (E545K, H1047R) in EpCAM‐positive CTCs and paired plasma‐ctDNA in breast cancer (BrCa). PIK3CA hotspot mutations in CTCs and ctDNA were analyzed using our previously developed highly sensitive (0.05%), specific, and validated assay in plasma‐ctDNA from 77 early and 73 metastatic BrCa patients and 40 healthy donors. We further analyzed and directly compared PIK3CA hotspot mutations in DNAs isolated from CellSearch^® cartridges (CTCs) and paired plasma‐ctDNA, in 56 cases of early and 27 cases of metastatic breast cancer, and 16 corresponding primary tumors. In plasma‐ctDNA,PIK3CA hotspot mutations were identified in 30/77(39.0%) early and 35/73(47.9%) metastatic BrCa cases; none (0/40, 0%) of the healthy donors’ plasma‐ctDNA samples were positive. Our direct comparison study in DNAs isolated from CellSearch^® cartridges (CTCs) and paired plasma‐ctDNA from the same blood draws has shown a lack of concordance in early BrCa (27/56, 48.2%), while the concordance in the metastatic setting was higher (18/27, 66.6%). Our results were validated by ddPCR methodology, and the concordance between our assay and ddPCR for PIK3CA E545K hotspot mutation was 30/37 (81.1%). In many cases, PIK3CA hotspot mutations were detected in samples found to be negative for CTCs in CellSearch^®. Our data demonstrated for the first time that (a) PIK3CA hotspot mutations are present at high frequencies in CTCs isolated from CellSearch^® cartridges and paired plasma‐ctDNA both in early and metastatic BrCa, (b) the detection and concordance of PIK3CA hotspot mutations between plasma‐ctDNA and CTCs are higher in the metastatic setting, (c) PIK3CA mutational status significantly changes after therapeutic intervention, and (d) PIK3CA mutation detection in CTCs and plasma‐ctDNA provides complementary information.

Prognostic nomogram based on immune scores for breast cancer patients

Background

Increased attention has been focused on cancer immunity gene signature. However, the threshold of immune scores to predict disease‐free survival (DFS) and overall survival (OS) in breast cancer has not yet been defined. This study aimed to explore the association of immune scores with prognosis and build a clinical nomogram to predict the survival of patients with breast cancer.

Methods

A total of 986 subjects were analyzed, and clinicopathological characteristics and immune scores were obtained from the TCGA database. Cox proportional hazards regression model was used to estimate the adjusted hazard ratios (HRs). Based on results of multivariate analysis, nomograms were built. The models were subjected to bootstrap internal validation. The predictive accuracy and discriminative ability were measured by concordance index (C‐index) and the calibration curve.

Results

The patients were divided into three subgroups according to their immune scores. We found that compared with patients with low immune scores, those with intermediate and high immune scores had significantly improved DFS (HR and 95% confidence interval [CI]: 0.439 [0.242‐0.799], 0.541 [0.343‐0.855], respectively), whereas only intermediate immune scores significantly indicated better OS (HR and 95% CI: 0.385 [0.163‐0.910]). The C‐index for DFS and OS prediction was 0.723 (95% CI, 0.661‐0.785) and 0.800 (95% CI, 0.724‐0.877), respectively. The calibration curves for probability of 3‐ and 5‐year DFS showed significant agreement between nomogram predictions and the actual observations.

Conclusions

High and/or intermediate immune scores are significantly correlated with better DFS and OS in patients with breast cancer. Moreover, the nomograms for predicting prognosis may help to estimate the survival of patients.

PIK3CA hotspot mutations in circulating tumor cells and paired circulating tumor DNA in breast cancer: a direct comparison study

Liquid biopsy analysis, mainly based on circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), provides an extremely powerful tool for the molecular profiling of cancer patients in real time. In this study, we directly compared PIK3CA hotspot mutations (E545K, H1047R) in EpCAM-positive CTCs and paired plasma-ctDNA in breast cancer (BrCa). PIK3CA hotspot mutations in CTCs and ctDNA were analyzed using our previously developed highly sensitive (0.05%), specific, and validated assay in plasma-ctDNA from 77 early and 73 metastatic BrCa patients and 40 healthy donors. We further analyzed and directly compared PIK3CA hotspot mutations in DNAs isolated from CellSearch^® cartridges (CTCs) and paired plasma-ctDNA, in 56 cases of early and 27 cases of metastatic breast cancer, and 16 corresponding primary tumors. In plasma-ctDNA, PIK3CA hotspot mutations were identified in 30/77(39.0%) early and 35/73(47.9%) metastatic BrCa cases; none (0/40, 0%) of the healthy donors' plasma-ctDNA samples were positive. Our direct comparison study in DNAs isolated from CellSearch^® cartridges (CTCs) and paired plasma-ctDNA from the same blood draws has shown a lack of concordance in early BrCa (27/56, 48.2%), while the concordance in the metastatic setting was higher (18/27, 66.6%). Our results were validated by ddPCR methodology, and the concordance between our assay and ddPCR for PIK3CA E545K hotspot mutation was 30/37 (81.1%). In many cases, PIK3CA hotspot mutations were detected in samples found to be negative for CTCs in CellSearch^® . Our data demonstrated for the first time that (a) PIK3CA hotspot mutations are present at high frequencies in CTCs isolated from CellSearch^® cartridges and paired plasma-ctDNA both in early and metastatic BrCa, (b) the detection and concordance of PIK3CA hotspot mutations between plasma-ctDNA and CTCs are higher in the metastatic setting, (c) PIK3CA mutational status significantly changes after therapeutic intervention, and (d) PIK3CA mutation detection in CTCs and plasma-ctDNA provides complementary information.

Androgen receptor expression in circulating tumor cells of patients with metastatic breast cancer

The androgen receptor (AR) has potential clinical relevance in metastatic breast cancer (mBC) since it might be a treatment target and has been associated with endocrine resistance. A minimal-invasive way to determine AR expression on metastatic tumor cells is by characterization of circulating tumor cells (CTCs). Here, we assessed AR mRNA expression in CTCs (CTC-AR) and in matched primary tumor samples from mBC patients representing different breast cancer subtypes. In addition, we explored CTC-AR-status in relation to outcome on endocrine therapy. AR, and 92 AR or estrogen receptor (ER) related genes, were measured in CellSearch-enriched CTCs from 124 mBC patients and in 52 matched FFPE primary tissues using quantitative reverse-transcriptase PCR. AR in CTCs was considered positive if the expression was 1 standard deviation higher than the expression measured in 11 healthy blood donors. A total of 31% of the mBC patients had AR-positive (AR+) CTCs. 58% of the matched CTC and primary tumor samples were discordant with respect to AR status, observing both switches from AR+ to AR-negative (AR-) and vice versa. There was no statistically significant difference in progression-free survival for patients treated with ER-targeting drugs and CTC-AR-status (13 AR+/ 37 AR- cases, p = 0.28). Thus, AR can be determined in RNA isolated from CTCs, with in our set 31% AR-positive samples. Given the discordance between AR status in CTC samples and corresponding primary tumors, determination of AR expression in CTCs might be a promising tool to select mBC patients for AR inhibiting agents.

An Optimized Workflow to Evaluate Estrogen Receptor Gene Mutations in Small Amounts of Cell-Free DNA

The detection of mutated genes in cell-free DNA (cfDNA) in plasma has emerged as an important minimally invasive way to obtain detailed information regarding tumor biology. Reliable determination of circulating tumor-derived DNA, often present at a low quantity amidst an excess of normal DNA in plasma, would be of added value for screening and monitoring of cancer patients and for hypothesis-generating studies in valuable retrospective cohorts. Our aim was to establish a workflow to simultaneously assess four hotspot estrogen receptor mutations (mESR1) in cfDNA isolated from only 200 μL of plasma by means of uniplex or multiplex pre-amplification combined with digital PCR. This workflow was then applied in metastatic breast cancer (MBC) patients receiving systemic therapies for MBC. In accordance with previous studies, estrogen receptor mutations were more frequently detected in endocrine-treated MBC patients at progressive disease [34.1% (15/44)] than before the start of endocrine therapy [3.9% (2/51); P = 0.001]. For a subset of samples, results were compared with analysis of these mutations by Oncomine-targeted next-generation sequencing, which, although requiring a higher cfDNA input, yielded concordant results. The data establish development and validation of a digital PCR workflow for the simultaneous detection of several tumor-derived mutations in minute amounts of cfDNA and show the potential of this workflow for use on archived volume-limited blood samples.

American Joint Committee on Cancer's Staging System for Breast Cancer, Eighth Edition: What the Radiologist Needs to Know

The TNM staging system for cancer was developed by Pierre Denoix in France in the 1940s and 1950s. The North American effort to standardize the TNM system for cancer staging was first organized in 1959 as the American Joint Committee for Cancer Staging and End-Results Reporting, which is now the American Joint Committee on Cancer (AJCC). The most recent edition of the AJCC Cancer Staging Manual, the eighth edition, was globally adopted on January 1, 2018. Previous editions of the manual have relied on anatomic methods of staging alone, which used population-based survival data to predict clinical outcomes. In the era of precision medicine, the major change in the eighth edition is the incorporation of prognostic biomarkers to more accurately predict clinical outcomes and treatment response on an individual basis, without relying solely on the anatomic extent of disease. Factors such as tumor grade, hormone receptor and oncogene expression, and multigene panel recurrence scores are now integrated with anatomic information to yield a final prognostic stage group, which will provide better stratification of patient prognosis. The purpose of this article is to review the major changes in the AJCC eighth edition for breast cancer staging, review anatomic TNM staging, familiarize the radiologist with prognostic biomarkers and prognostic staging, and identify key sites of disease that may alter clinical management. ^©RSNA, 2018.

ROR1 is highly expressed in circulating tumor cells and promotes invasion of pancreatic cancer

Pancreatic cancer (PaC) is an aggressive malignancy, which is associated with high levels of metastasis. Circulating tumor cells (CTCs), which may be considered a functional biomarker and promising treatment strategy for metastasis, are associated with the prognosis and progression of various metastatic cancers, including PaC. Receptor tyrosine kinase‑like orphan receptor 1 (ROR1) expression contributes to cell metastasis and poor clinical outcomes in malignant tumors. The present study aimed to explore the function of ROR1 in PaC CTCs. Reverse transcription‑quantitative polymerase chain reaction and western blot analysis were used to examine the expression of ROR1, E‑cadherin and N‑cadherin. Cell proliferative and invasive ability was assessed by MTT and Transwell assays, respectively. The results revealed that the mRNA and protein expression levels of ROR1 were augmented in PaC tissues. Furthermore, the mRNA expression levels of ROR1 were higher in CTCs compared with in peripheral blood cells, and ROR1 was more highly expressed in CTCs than in cells. Notably, CTCs exhibited a markedly greater proliferative and invasive capacity than PANC‑1 and SW‑1990 cells, whereas knockdown of endogenous ROR1 by small interfering RNA led to suppression of the invasion of CTCs. In addition, it was revealed that the mechanism underlying the effects of ROR1 on PaC CTC metastasis may involve the epithelial‑mesenchymal transition process. In conclusion, ROR1 may be considered a potential biomarker and therapeutic target for the treatment of PaC.

M-bioscore: proposing a new statistical model for prognostic factors in metastatic breast cancer patients

Aim: The current study aims to propose and internally validate ‘M-bioscore’, which is a model to help predict the outcomes of untreated metastatic breast cancer patients. Methodology: Surveillance, epidemiology and end results (SEER) database (2010–2013) was accessed. Patients were divided into two groups: a training set and a validation set. Through a Cox proportional model, multivariate analysis for potential prognostic factors was performed. M-bioscore was calculated for all patients. Survival analyses were conducted through Kaplan–Meier analysis/log-rank testing. Results: A total of 6655 metastatic breast cancer patients were analyzed. In the training set, the following factors were linked to better cancer-specific survival in multivariate analysis: estrogen receptor positivity, isolated distant nodal metastases, progesterone receptor positivity, lower nuclear grade and HER2 neu positivity (p < 0.01). Cancer-specific survival was then assessed according to M-bioscore. Adjusted Cox regression cause-specific hazard (using breast cancer death as the event of interest) was evaluated in the validation cohort. Pairwise hazard ratio comparisons between different scores were significant (p < 0.05) except for the comparison between score 6 and 7. C-index for the validation cohort was 0.665 (Standard error (SE): 0.010; 95% CI: 0.646- 0.685).Conclusion: M-bioscore can predict the outcomes of untreated metastatic breast cancer patients. Validation of external datasets is needed.

RNA Profiles of Circulating Tumor Cells and Extracellular Vesicles for Therapy Stratification of Metastatic Breast Cancer Patients

BACKGROUND

Liquid biopsies are discussed to provide surrogate markers for therapy stratification and monitoring. We compared messenger RNA (mRNA) profiles of circulating tumor cells (CTCs) and extracellular vesicles (EVs) in patients with metastatic breast cancer (MBC) to estimate their utility in therapy management.

METHODS

Blood was collected from 35 hormone receptor-positive/HER2-negative patients with MBC at the time of disease progression and at 2 consecutive staging time points. CTCs were isolated from 5 mL of blood by positive immunomagnetic selection, and EVs from 4 mL of plasma by a membrane affinity-based procedure. mRNA was reverse transcribed, preamplified, and analyzed for 18 genes by multimarker quantitative polymerase chain reaction (qPCR) assays. RNA profiles were normalized to healthy donor controls (n = 20), and results were correlated with therapy outcome.

RESULTS

There were great differences in mRNA profiles of EVs and CTCs, with only 5% (21/403) of positive signals identical in both fractions. Transcripts involved in the PI3K signaling pathway were frequently overexpressed in CTCs, and AURKA, PARP1, and SRC signals appeared more often in EVs. Of all patients, 40% and 34% showed ERBB2 and ERBB3 signals, respectively, in CTCs, which was significantly associated with disease progression (P = 0.007). Whereas MTOR signals in CTCs significantly correlated with response (P = 0.046), signals in EVs indicated therapy failure (P = 0.011). The presence of AURKA signals in EVs seemed to be a marker for the indication of unsuccessful treatment of bone metastasis.

CONCLUSIONS

These results emphasize the potential of CTCs and EVs for therapy monitoring and the need for critical evaluation of the implementation of any liquid biopsy in clinical practice.

Perspective on Cancer Therapeutics Utilizing Analysis of Circulating Tumor Cells

Various methods are available for cancer screening, and the methods are performed depending on the origin site of cancer. Among these methods, biopsy followed by medical imaging is the most common. After cancer progression is determined, an optimal treatment—such as surgery, chemotherapy, and/or radiation therapy—is selected. A new assay has been developed that detects circulating tumor cells (CTCs). Tracking changes in CTCs may reveal important tumoral sensitivity information or resistance patterns to specific regimens and prompt changes in therapy on a personalized basis. Characterization of CTCs at the DNA, RNA, and protein levels is important for gaining insight for clinical applications. A small number of CTCs can be analyzed to obtain genome information such as the progression of cancer including metastasis, even in a single cluster. Although many clinical studies, particularly CTC enumeration and detection of specific oncogene expression, have increased the success rate of diagnosis and predicting prognosis, there is no consensus regarding the technical approaches and various aspects of the methodology, making it difficult to standardize optimal methods for CTC analysis. However, ongoing technological advances are currently being achieved and large-scale clinical studies are being conducted. Applying CTC analysis in the clinic would be very useful for advancing diagnosis, prognosis prediction, and therapeutics.

Perspective on Cancer Therapeutics Utilizing Analysis of Circulating Tumor Cells

Various methods are available for cancer screening, and the methods are performed depending on the origin site of cancer. Among these methods, biopsy followed by medical imaging is the most common. After cancer progression is determined, an optimal treatment-such as surgery, chemotherapy, and/or radiation therapy-is selected. A new assay has been developed that detects circulating tumor cells (CTCs). Tracking changes in CTCs may reveal important tumoral sensitivity information or resistance patterns to specific regimens and prompt changes in therapy on a personalized basis. Characterization of CTCs at the DNA, RNA, and protein levels is important for gaining insight for clinical applications. A small number of CTCs can be analyzed to obtain genome information such as the progression of cancer including metastasis, even in a single cluster. Although many clinical studies, particularly CTC enumeration and detection of specific oncogene expression, have increased the success rate of diagnosis and predicting prognosis, there is no consensus regarding the technical approaches and various aspects of the methodology, making it difficult to standardize optimal methods for CTC analysis. However, ongoing technological advances are currently being achieved and large-scale clinical studies are being conducted. Applying CTC analysis in the clinic would be very useful for advancing diagnosis, prognosis prediction, and therapeutics.

Expanded Genomic Profiling of Circulating Tumor Cells in Metastatic Breast Cancer Patients to Assess Biomarker Status and Biology Over Time (CALGB 40502 and CALGB 40503, Alliance)

Purpose: We profiled circulating tumor cells (CTCs) to study the biology of blood-borne metastasis and to monitor biomarker status in metastatic breast cancer (MBC).Methods: CTCs were isolated from 105 patients with MBC using EPCAM-based immunomagnetic enrichment and fluorescence-activated cells sorting (IE/FACS), 28 of whom had serial CTC analysis (74 samples, 2-5 time points). CTCs were subjected to microfluidic-based multiplex QPCR array of 64 cancer-related genes (n = 151) and genome-wide copy-number analysis by array comparative genomic hybridization (aCGH; n = 49).Results: Combined transcriptional and genomic profiling showed that CTCs were 26% ESR1-ERBB2-, 48% ESR1+ERBB2-, and 27% ERBB2+ Serial testing showed that ERBB2 status was more stable over time compared with ESR1 and proliferation (MKI67) status. While cell-to-cell heterogeneity was observed at the single-cell level, with increasingly stable expression in larger pools, patient-specific CTC expression "fingerprints" were also observed. CTC copy-number profiles clustered into three groups based on the extent of genomic aberrations and the presence of large chromosomal imbalances. Comparative analysis showed discordance in ESR1/ER (27%) and ERBB2/HER2 (23%) status between CTCs and matched primary tumors. CTCs in 65% of the patients were considered to have low proliferation potential. Patients who harbored CTCs with high proliferation (MKI67) status had significantly reduced progression-free survival (P = 0.0011) and overall survival (P = 0.0095) compared with patients with low proliferative CTCs.Conclusions: We demonstrate an approach for complete isolation of EPCAM-positive CTCs and downstream comprehensive transcriptional/genomic characterization to examine the biology and assess breast cancer biomarkers in these cells over time. Clin Cancer Res; 24(6); 1486-99. ©2018 AACR.

Molecular characteristics of circulating tumor cells resemble the liver metastasis more closely than the primary tumor in metastatic colorectal cancer

Background

CTCs are a promising alternative for metastatic tissue biopsies for use in precision medicine approaches. We investigated to what extent the molecular characteristics of circulating tumor cells (CTCs) resemble the liver metastasis and/or the primary tumor from patients with metastatic colorectal cancer (mCRC).

Results

The CTC profiles were concordant with the liver metastasis in 17/23 patients (74%) and with the primary tumor in 13 patients (57%). The CTCs better resembled the liver metastasis in 13 patients (57%), and the primary tumor in five patients (22%). The strength of the correlations was not associated with clinical parameters. Nine genes (CDH1, CDH17, CDX1, CEACAM5, FABP1, FCGBP, IGFBP3, IGFBP4, and MAPT) displayed significant differential expressions, all of which were downregulated, in CTCs compared to the tissues in the 23 patients.

Patients and Methods

Patients were retrospectively selected from a prospective study. Using the CellSearch System, CTCs were enumerated and isolated just prior to liver metastasectomy. A panel of 25 CTC-specific genes was measured by RT-qPCR in matching CTCs, primary tumors, and liver metastases. Spearman correlation coefficients were calculated and considered as continuous variables with r=1 representing absolute concordance and r= -1 representing absolute discordance. A cut-off of r>0.1 was applied in order to consider profiles to be concordant.

Conclusions

In the majority of the patients, CTCs reflected the molecular characteristics of metastatic cells better than the primary tumors. Genes involved in cell adhesion and epithelial-to-mesenchymal transition were downregulated in the CTCs. Our results support the use of CTC characterization as a liquid biopsy for precision medicine.

Establishment of a multimarker qPCR panel for the molecular characterization of circulating tumor cells in blood samples of metastatic breast cancer patients during the course of palliative treatment

Background

Circulating tumor cells (CTC) are discussed to be an ideal surrogate marker for individualized treatment in metastatic breast cancer (MBC) since metastatic tissue is often difficult to obtain for repeated analysis. We established a nine gene qPCR panel to characterize the heterogeneous CTC population in MBC patients including epithelial CTC, their receptors (EPCAM, ERBB2, ERBB3, EGFR) CTC in Epithelial-Mesenchymal-Transition [(EMT); PIK3CA, AKT2), stem cell-like CTC (ALDH1) as well as resistant CTC (ERCC1, AURKA] to identify individual therapeutic targets.

Results

At TP0, at least one marker was detected in 84%, at TP1 in 74% and at TP2 in 79% of the patients, respectively. The expression of ERBB2, ERBB3 and ERCC1 alone or in combination with AURKA was significantly associated with therapy failure. ERBB2 + CTC were only detected in patients not receiving ERBB2 targeted therapies which correlated with no response. Furthermore, patients responding at TP2 had a significantly prolonged overall-survival than patients never responding (p = 0.0090).

Patients and Methods

2 × 5 ml blood of 62 MBC patients was collected at the time of disease progression (TP0) and at two clinical staging time points (TP1 and TP2) after 8–12 weeks of chemo-, hormone or antibody therapy for the detection of CTC (AdnaTest EMT-2/StemCell Select™, QIAGEN Hannover GmbH, Germany). After pre-amplification, multiplex qPCR was performed. Establishment was performed using various cancer cell lines. PTPRC (Protein tyrosine phosphatase receptor type C) and GAPDH served as controls.

Conclusions

Monitoring MBC patients using a multimarker qPCR panel for the characterization of CTC might help to treat patients accordingly in the future.

Analysis of tumor template from multiple compartments in a blood sample provides complementary access to peripheral tumor biomarkers

Targeted cancer therapeutics are promised to have a major impact on cancer treatment and survival. Successful application of these novel treatments requires a molecular definition of a patient's disease typically achieved through the use of tissue biopsies. Alternatively, allowing longitudinal monitoring, biomarkers derived from blood, isolated either from circulating tumor cell derived DNA (ctcDNA) or circulating cell-free tumor DNA (ccfDNA) may be evaluated. In order to use blood derived templates for mutational profiling in clinical decisions, it is essential to understand the different template qualities and how they compare to biopsy derived template DNA as both blood-based templates are rare and distinct from the gold-standard. Using a next generation re-sequencing strategy, concordance of the mutational spectrum was evaluated in 32 patient-matched ctcDNA and ccfDNA templates with comparison to tissue biopsy derived DNA template. Different CTC antibody capture systems for DNA isolation from patient blood samples were also compared. Significant overlap was observed between ctcDNA, ccfDNA and tissue derived templates. Interestingly, if the results of ctcDNA and ccfDNA template sequencing were combined, productive samples showed similar detection frequency (56% vs 58%), were temporally flexible, and were complementary both to each other and the gold standard. These observations justify the use of a multiple template approach to the liquid biopsy, where germline, ctcDNA, and ccfDNA templates are employed for clinical diagnostic purposes and open a path to comprehensive blood derived biomarker access.

Clinical significance of detecting CSF-derived tumor cells in breast cancer patients with leptomeningeal metastasis

Despite marked advances in breast cancer therapy, breast cancer-associated leptomeningeal metastasis (LM), a particularly aggressive syndrome with multifocal seeding of the leptomeninges by tumor cells, still carries an abysmal prognosis. A major problem with breast cancer LM surveillance is the lack of an effective and sensitive means to track dynamic changes of the disease. Cytology detection of cerebrospinal fluid (CSF) is considered the gold standard for LM diagnosis but has a high false-negative rate with a limited sensitivity. Here we applied subtraction enrichment and immunostaining-fluorescence in situ (SE-i•FISH) method, a technique previously used for isolating circulating tumor cells (CTCs) from the peripheral blood, to detect, enumerate, and track cerebrospinal fluid-derived tumor cells (CSFTCs) in CSF samples from 8 breast cancer patients. Comparing with cytology test, we found SE-i•FISH method can accurately and feasibly detect CSFTCs for the diagnosis of breast cancer-associated LM and monitor the disease progression. We also isolated and cultured CSFTCs from these cancer patients and performed genomic sequencing on CSFTCs of two patients. Genomic analysis of CSFTCs against corresponding archival primary breast tumors revealed clonal relationships with some ongoing evolution. Further drug sensitivity test on cultured CSFTCs based on genomic analysis data helped identify promising treatment options for the patient tested. Together, our results suggest that CSFTCs detection using SE-i•FISH platform could serve as a sensitive and accurate method to make the diagnosis and a promising approach to monitor tumor dynamics and treatment response for breast cancer-associated LM.

Estrogen receptor mutations and splice variants determined in liquid biopsies from metastatic breast cancer patients

Mutations and splice variants in the estrogen receptor (ER) gene, ESR1, may yield endocrine resistance in metastatic breast cancer (MBC) patients. These putative endocrine resistance markers are likely to emerge during treatment, and therefore, its detection in liquid biopsies, such as circulating tumor cells (CTCs) and cell‐free DNA (cfDNA), is of great interest. This research aimed to determine whether ESR1 mutations and splice variants occur more frequently in CTCs of MBC patients progressing on endocrine treatment. In addition, the presence of ESR1 mutations was evaluated in matched cfDNA and compared to CTCs. CellSearch‐enriched CTC fractions (≥5/7.5 mL) of two MBC cohorts were evaluated, namely (a) patients starting first‐line endocrine therapy (n = 43, baseline cohort) and (b) patients progressing on any line of endocrine therapy (n = 40, progressing cohort). ESR1 hotspot mutations (D538G and Y537S/N/C) were evaluated in CTC‐enriched DNA using digital PCR and compared with matched cfDNA (n = 18 baseline cohort; n = 26 progressing cohort). Expression of ESR1 full‐length and 4 of its splice variants (∆5, ∆7, 36 kDa, and 46 kDa) was evaluated in CTC‐enriched mRNA. It was observed that in the CTCs, the ESR1 mutations were not enriched in the progressing cohort (8%), when compared with the baseline cohort (5%) (P = 0.66). In the cfDNA, however, ESR1 mutations were more prevalent in the progressing cohort (42%) than in the baseline cohort (11%) (P = 0.04). Three of the same mutations were observed in both CTCs and cfDNA, 1 mutation in CTCs only, and 11 in cfDNA only. Only the ∆5 ESR1 splice variant was CTC‐specific expressed, but was not enriched in the progressing cohort. In conclusion, sensitivity for detecting ESR1 mutations in CTC‐enriched fractions was lower than for cfDNA. ESR1 mutations detected in cfDNA, rarely present at the start of first‐line endocrine therapy, were enriched at progression, strongly suggesting a role in conferring endocrine resistance in MBC.

Estrogen receptor mutations and splice variants determined in liquid biopsies from metastatic breast cancer patients

Mutations and splice variants in the estrogen receptor (ER) gene, ESR1, may yield endocrine resistance in metastatic breast cancer (MBC) patients. These putative endocrine resistance markers are likely to emerge during treatment, and therefore, its detection in liquid biopsies, such as circulating tumor cells (CTCs) and cell-free DNA (cfDNA), is of great interest. This research aimed to determine whether ESR1 mutations and splice variants occur more frequently in CTCs of MBC patients progressing on endocrine treatment. In addition, the presence of ESR1 mutations was evaluated in matched cfDNA and compared to CTCs. CellSearch-enriched CTC fractions (≥5/7.5 mL) of two MBC cohorts were evaluated, namely (a) patients starting first-line endocrine therapy (n = 43, baseline cohort) and (b) patients progressing on any line of endocrine therapy (n = 40, progressing cohort). ESR1 hotspot mutations (D538G and Y537S/N/C) were evaluated in CTC-enriched DNA using digital PCR and compared with matched cfDNA (n = 18 baseline cohort; n = 26 progressing cohort). Expression of ESR1 full-length and 4 of its splice variants (∆5, ∆7, 36 kDa, and 46 kDa) was evaluated in CTC-enriched mRNA. It was observed that in the CTCs, the ESR1 mutations were not enriched in the progressing cohort (8%), when compared with the baseline cohort (5%) (P = 0.66). In the cfDNA, however, ESR1 mutations were more prevalent in the progressing cohort (42%) than in the baseline cohort (11%) (P = 0.04). Three of the same mutations were observed in both CTCs and cfDNA, 1 mutation in CTCs only, and 11 in cfDNA only. Only the ∆5 ESR1 splice variant was CTC-specific expressed, but was not enriched in the progressing cohort. In conclusion, sensitivity for detecting ESR1 mutations in CTC-enriched fractions was lower than for cfDNA. ESR1 mutations detected in cfDNA, rarely present at the start of first-line endocrine therapy, were enriched at progression, strongly suggesting a role in conferring endocrine resistance in MBC.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Circulating tumour cells from patients with colorectal cancer have cancer stem cell hallmarks in ex vivo culture

OBJECTIVE

Although counting of circulating tumour cells (CTC) has attracted a broad interest as potential markers of tumour progression and treatment response, the lack of functional characterisation of these cells had become a bottleneck in taking these observations to the clinic. Our objective was to culture these cells in order to understand them and exploit their therapeutic potential to the full.

DESIGN

Here, hypothesising that some CTC potentially have cancer stem cell (CSC) phenotype, we generated several CTC lines from the blood of patients with advanced metastatic colorectal cancer (CRC) based on their self-renewal abilities. Multiple standard tests were then employed to characterise these cells.

RESULTS

Our CTC lines self-renew, express CSC markers and have multilineage differentiation ability, both in vitro and in vivo. Patient-derived CTC lines are tumorigenic in subcutaneous xenografts and are also able to colonise the liver after intrasplenic injection. RNA sequencing analyses strikingly demonstrate that drug metabolising pathways represent the most upregulated feature among CTC lines in comparison with primary CRC cells grown under similar conditions. This result is corroborated by the high resistance of the CTC lines to conventional cytotoxic compounds.

CONCLUSIONS

Taken together, our results directly demonstrate the existence of patient-derived colorectal CTCs that bear all the functional attributes of CSCs. The CTC culture model described here is simple and takes <1 month from blood collection to drug testing, therefore, routine clinical application could facilitate access to personalised medicine.

CLINICAL TRIAL REGISTRATION

ClinicalTrial.gov NCT01577511.

Circulating tumor cells: clinical validity and utility

Circulating tumor cells (CTCs) are rare tumor cells and have been investigated as diagnostic, prognostic and predictive biomarkers in many types of cancer. Although CTCs are not currently used in clinical practice, CTC studies have accumulated a high level of clinical validity, especially in breast, lung, prostate and colorectal cancers. In this review, we present an overview of the current clinical validity of CTCs in metastatic and non-metastatic disease, and the main concepts and studies investigating the clinical utility of CTCs. In particular, this review will focus on breast, lung, colorectal and prostate cancer. Three major topics concerning the clinical utility of CTC are discussed-(1) treatment based on CTCs used as liquid biopsy, (2) treatment based on CTC count or CTC variations, and (3) treatment based on CTC biomarker expression. A summary of published or ongoing phase II and III trials is also presented.

Detection of Circulating Tumour Cells in Urothelial Cancers and Clinical Correlations: Comparison of Two Methods

Circulating tumour cells (CTC) are identified exploiting their protein/gene expression patterns or distinct size compared to blood cells. Data on CTC in bladder cancer (BC) are still scarce. We comparatively analyzed CTC enrichment by AdnaTest ProstateCancerSelect (AT) and ScreenCell®Cyto (SC) kits, combined with identification by EPCAM, MUC1, and ERBB2 expression and by cytological criteria, respectively, in 19 nonmetastatic (M₀) and 47 metastatic (M₊) BC patients, at baseline (T₀) and during treatment (T₁). At T₀, CTC positivity rates by AT were higher in M₊ compared to M₀ cases (57.4% versus 25%, p = 0.041). EPCAM was detected in 75% of CTC-positive samples by AT, showing increasing expression levels from T₀ to T₁ (median (interquartile range, IQR): 0.18 (0.07-0.42) versus 0.84 (0.33-1.84), p = 0.005) in M₊ cases. Overall, CTC positivity by SC was around 80% regardless of clinical setting and time point of analysis, except for a lower occurrence at T₁ in M₀ cases. At T₀, circulating tumour microemboli were more frequently (25% versus 8%) detected and more numerous in M₊ compared to M₀ patients. The approach used for CTC detection impacts the outcome of CTC studies. Further investigations are required to clarify the clinical validity of AT and SC in specific BC clinical contexts.

Prognostic Impact of HER2 and ER Status of Circulating Tumor Cells in Metastatic Breast Cancer Patients with a HER2-Negative Primary Tumor

BACKGROUND

Preclinical and clinical studies have reported that human epidermal growth factor receptor 2 (HER2) overexpression yields resistance to endocrine therapies. Here the prevalence and prognostic impact of HER2-positive circulating tumor cells (CTCs) were investigated retrospectively in metastatic breast cancer (MBC) patients with a HER2-negative primary tumor receiving endocrine therapy. Additionally, the prevalence and prognostic significance of HER2-positive CTCs were explored in a chemotherapy cohort, as well as the prognostic impact of the estrogen receptor (ER) CTC status in both cohorts.

METHODS

Included were MBC patients with a HER2-negative primary tumor, with ≥1 detectable CTC, starting a new line of treatment. CTCs were enumerated using the CellSearch system, characterized for HER2 with the CellSearch anti-HER2 phenotyping reagent, and characterized for ER mRNA expression. Primary end point was progression-free rate after 6 months (PFR6months) of endocrine treatment in HER2-positive versus HER2-negative CTC patients.

RESULTS

HER2-positive CTCs were present in 29% of all patients. In the endocrine cohort (n=72), the PFR6months was 53% for HER2-positive versus 68% for HER2-negative CTC patients (P=.23). In the chemotherapy cohort (n=82), no prognostic value of HER2-positive CTCs on PFR6months was observed either. Discordances in ER status between the primary tumor and CTCs occurred in 25% of all patients but had no prognostic value in exploratory survival analyses.

CONCLUSION

Discordances regarding HER2 status and ER status between CTCs and the primary tumor occurred frequently but had no prognostic impact in our MBC patient cohorts.

An 8-gene mRNA expression profile in circulating tumor cells predicts response to aromatase inhibitors in metastatic breast cancer patients

Background

Molecular characterization of circulating tumor cells (CTC) is promising for personalized medicine. We aimed to identify a CTC gene expression profile predicting outcome to first-line aromatase inhibitors in metastatic breast cancer (MBC) patients. Methods: CTCs were isolated from 78 MBC patients before treatment start. mRNA expression levels of 96 genes were measured by quantitative reverse transcriptase polymerase chain reaction. After applying predefined exclusion criteria based on lack of sufficient RNA quality and/or quantity, the data from 45 patients were used to construct a gene expression profile to predict poor responding patients, defined as disease progression or death <9 months, by a leave-one-out cross validation.

Results

Of the 45 patients, 19 were clinically classified as poor responders. To identify them, the 75 % most variable genes were used to select genes differentially expressed between good and poor responders. An 8-gene CTC predictor was significantly associated with outcome (Hazard Ratio [HR] 4.40, 95 % Confidence Interval [CI]: 2.17–8.92, P < 0.001). This predictor identified poor responding patients with a sensitivity of 63 % and a positive predictive value of 75 %, while good responding patients were correctly predicted in 85 % of the cases. In multivariate Cox regression analysis, including CTC count at baseline, the 8-gene CTC predictor was the only factor independently associated with outcome (HR 4.59 [95 % CI: 2.11–9.56], P < 0.001). This 8-gene signature was not associated with outcome in a group of 71 MBC patients treated with systemic treatments other than AI.

Conclusions

An 8-gene CTC predictor was identified which discriminates good and poor outcome to first-line aromatase inhibitors in MBC patients. Although results need to be validated, this study underscores the potential of molecular characterization of CTCs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2155-y) contains supplementary material, which is available to authorized users.

Gene expression profiling and DNA methylation analyses of CTCs

A variety of molecular assays have been developed for CTCs detection and molecular characterization. Molecular assays are based on the nucleic acid analysis in CTCs and are based on total RNA isolation and subsequent mRNA quantification of specific genes, or isolation of genomic DNA that can be for DNA methylation studies and mutation analysis. This review is mainly focused on gene expression and methylation studies in CTCs in various types of cancer.

Monocyte Activation in Immunopathology: Cellular Test for Development of Diagnostics and Therapy

Several highly prevalent human diseases are associated with immunopathology. Alterations in the immune system are found in such life-threatening disorders as cancer and atherosclerosis. Monocyte activation followed by macrophage polarization is an important step in normal immune response to pathogens and other relevant stimuli. Depending on the nature of the activation signal, macrophages can acquire pro- or anti-inflammatory phenotypes that are characterized by the expression of distinct patterns of secreted cytokines and surface antigens. This process is disturbed in immunopathologies resulting in abnormal monocyte activation and/or bias of macrophage polarization towards one or the other phenotype. Such alterations could be used as important diagnostic markers and also as possible targets for the development of immunomodulating therapy. Recently developed cellular tests are designed to analyze the phenotype and activity of living cells circulating in patient's bloodstream. Monocyte/macrophage activation test is a successful example of cellular test relevant for atherosclerosis and oncopathology. This test demonstrated changes in macrophage activation in subclinical atherosclerosis and breast cancer and could also be used for screening a panel of natural agents with immunomodulatory activity. Further development of cellular tests will allow broadening the scope of their clinical implication. Such tests may become useful tools for drug research and therapy optimization.

Circulating tumor cells in breast cancer

Over the past decade, technically reliable circulating tumor cell (CTC) detection methods allowed the collection of large datasets of CTC counts in cancer patients. These data can be used either as a dynamic prognostic biomarker or as tumor material for “liquid biopsy”. Breast cancer appears to be the cancer type in which CTC have been the most extensively studied so far, with level‐of‐evidence‐1 studies supporting the clinical validity of CTC count in both early and metastatic stage. This review summarizes and discusses the clinical results obtained in breast cancer patients, the issues faced by the molecular characterization of CTC and the biological findings about cancer biology and metastasis that were obtained from CTC.

In metastatic breast cancer, CTC count is a level‐of‐evidence 1 prognostic dynamic biomarker.

Several interventional trials are ongoing to demonstrate the clinical utility of CTC detection in metastatic breast cancer.

In early breast cancer, CTC count is also a prognostic biomarker, not correlated with the other usual prognostic factors.

Molecular characterization of CTC is promising, trials with anti‐HER2 therapy are ongoing.

Metastasis of circulating tumor cells: favorable soil or suitable biomechanics, or both?

Metastasis is the end product of a multistep process where cancer cells disseminate and home themselves in distant organs. Tumor cell extravasation is a rare, inefficient and transient event in nature and makes its studies very difficult. Noteworthy, little is known about how cancer cells arrest, adhere and pass through the endothelium of capillaries. Moreover, the key events driving metastatic growth in specific organs are not well understood. Thus, although metastasis is the leading cause of cancer-related death, how cancer cells acquire their abilities to colonize distant organs and why they do so in specific locations remain central questions in the understanding of this deadly disease. In this review, we would like to confront 2 concepts explaining the efficiency and location of metastatic secondary tumors. While the "seed and soil" hypothesis states that metastasis occurs at sites where the local microenvironment is favorable, the "mechanical" concept argues that metastatic seeding occurs at sites of optimal flow patterns. In addition, recent evidence suggests that the primary event driving tumor cell arrest before extravasation is mostly controlled by blood circulation patterns as well as mechanical cues during the process of extravasation. In conclusion, the organ tropism displayed by cancer cells during metastatic colonization is a multi-step process, which is regulated by the delivery and survival of circulating tumor cells (CTCs) through blood circulation, the ability of these CTCs to adhere and cross the physical barrier imposed by the endothelium and finally by the suitability of the soil to favor growth of secondary tumors.