Circulating tumor cells in colorectal cancer: correlation with clinical and pathological variables

Stage-Specific Plasma Metabolomic Profiles in Colorectal Cancer

Background/Objectives: The objective of this study was to investigate the metabolomic profiles of patients with colorectal cancer (CRC) across various stages of the disease. Methods: The plasma samples were obtained from 255 subjects, including patients with CRC in stages I-IV, polyps, and controls. We employed capillary electrophoresis time-of-flight mass spectrometry and liquid chromatography triple quadrupole mass spectrometry to analyze hydrophilic metabolites comprehensively. The data were randomly divided into two groups, and consistent differences observed in both groups were analyzed. Results: Acetylated polyamines, such as N1-acetylspermine and N1, N12-diacetylspermine, consistently showed elevated concentrations in stage IV compared to stages I-III. Non-acetylated polyamines, including spermine and spermidine, exhibited increasing trends from polyp to stage IV. Other metabolites, such as histidine and o-acetylcarnitine, showed decreasing trends across stages. While acetylated polyamines have been reported as CRC detection markers, our findings suggest that they also possess diagnostic potential for distinguishing stage IV from other stages. Conclusions: This study showed stage-specific changes in metabolic profiles, including polyamines, of colorectal cancer.

Prospects of liquid biopsy in the prognosis and clinical management of gastrointestinal cancers

Gastrointestinal (GI) cancers account for one-fourth of the global cancer incidence and are incriminated to cause one-third of cancer-related deaths. GI cancer includes esophageal, gastric, liver, pancreatic, and colorectal cancers, mostly diagnosed at advanced stages due to a lack of accurate markers for early stages. The invasiveness of diagnostic methods like colonoscopy for solid biopsy reduces patient compliance as it cannot be frequently used to screen patients. Therefore, minimally invasive approaches like liquid biopsy may be explored for screening and early identification of gastrointestinal cancers. Liquid biopsy involves the qualitative and quantitative determination of certain cancer-specific biomarkers in body fluids such as blood, serum, saliva, and urine to predict disease progression, therapeutic tolerance, toxicities, and recurrence by evaluating minimal residual disease and its correlation with other clinical features. In this review, we deliberate upon various tumor-specific cellular and molecular entities such as circulating tumor cells (CTCs), tumor-educated platelets (TEPs), circulating tumor DNA (ctDNA), cell-free DNA (cfDNA), exosomes, and exosome-derived biomolecules and cite recent advances pertaining to their use in predicting disease progression, therapy response, or risk of relapse. We also discuss the technical challenges associated with translating liquid biopsy into clinical settings for various clinical applications in gastrointestinal cancers.

Liquid biopsy in colorectal cancer

Liquid biopsy refers to a set of pathological samples retrieved from non-solid sources, such as blood, cerebrospinal fluid, urine, and saliva through non-invasive or minimally invasive approaches. In the recent decades, an increasing number of studies have focused on clinical applications and improving technological investigation of liquid biopsy biosources for diagnostic goals particularly in cancer. Materials extracted from these sources and used for medical evaluations include cells like circulating tumor cells (CTCs), tumor-educated platelets (TEPs), cell-free nucleic acids released by cells, such as circulating tumor DNA (ctDNA), cell-free DNA (cfDNA), cell-free RNA (cfRNA), and exosomes. Playing significant roles in the pathogenesis of human malignancies, analysis of these sources can provide easier access to genetic and transcriptomic information of the cancer tissue even better than the conventional tissue biopsy. Notably, they can represent the inter- and intra-tumoral heterogeneity and accordingly, liquid biopsies demonstrate strengths for improving diagnosis in early detection and screening, monitoring and follow-up after therapies, and personalization of therapeutical strategies in various types of human malignancies. In this review, we aim to discuss the roles, functions, and analysis approaches of liquid biopsy sources and their clinical implications in human malignancies with a focus on colorectal cancer.

Advances on Liquid Biopsy Analysis for Glioma Diagnosis

Gliomas comprise the most frequent primary central nervous system (CNS) tumors, characterized by remarkable genetic and epigenetic heterogeneity, difficulty in monitoring, and increased relapse and mortality rates. Tissue biopsy is an established method of tumor cell collection and analysis that enables diagnosis, classification of different tumor types, and prediction of prognosis upon confirmation of tumor's location for surgical removal. However, it is an invasive and often challenging procedure that cannot be used for frequent patient screening, detection of mutations, disease monitoring, or resistance to therapy. To this end, the minimally invasive procedure of liquid biopsy has emerged, allowing effortless tumor sampling and enabling continuous monitoring. It is considered a novel preferable way to obtain faster data on potential tumor risk, personalized diagnosis, prognosis, and recurrence evaluation. The purpose of this review is to describe the advances on liquid biopsy for glioma diagnosis and management, indicating several biomarkers that can be utilized to analyze tumor characteristics, such as cell-free DNA (cfDNA), cell-free RNA (cfRNA), circulating proteins, circulating tumor cells (CTCs), and exosomes. It further addresses the benefit of combining liquid biopsy with radiogenomics to facilitate early and accurate diagnoses, enable precise prognostic assessments, and facilitate real-time disease monitoring, aiming towards more optimal treatment decisions.

MiSelect R System: the validation of a new detection system of CTCs and their correlation with prognosis in non-metastatic CRC patients

Circulating tumor cells (CTCs) in blood are accepted as a prognostic marker for patients with metastatic colorectal cancer (CRC). However, there is limited data on the use of CTCs as a prognostic marker for non-metastatic patients. In the current study, we used a rare cell automated analysis platform, the MiSelect R System, to enumerate CTCs from blood in non-metastatic CRC patients, and corelated the number of CTCs with the clinical staging and survival. The presence of CTCs in mesenteric vein blood (MVB) samples from 101 CRC patients was significantly associated with T stage. Patients with 1 or more CTCs per 8 mL of MVB exhibited significantly worse disease-free survival (DFS) and cancer-specific survival (CSS) compared to patient without CTCs. The presence of CTCs before surgery is an independent marker for both DFS and CSS. CTC presence after surgical resection is also a prognostic marker. CTCs are a potentially useful prognostic and predictive biomarker in non-metastatic CRC patients that may further stratify patient's risk status within different stages of disease.

Gene Expression Analysis of Immune Regulatory Genes in Circulating Tumour Cells and Peripheral Blood Mononuclear Cells in Patients with Colorectal Carcinoma

Information regarding genetic alterations of driver cancer genes in circulating tumour cells (CTCs) and their surrounding immune microenvironment nowadays can be employed as a real-time monitoring platform for translational applications such as patient response to therapeutic targets, including immunotherapy. This study aimed to investigate the expression profiling of these genes along with immunotherapeutic target molecules in CTCs and peripheral blood mononuclear cells (PBMCs) in patients with colorectal carcinoma (CRC). Expression of p53, APC, KRAS, c-Myc, and immunotherapeutic target molecules PD-L1, CTLA-4, and CD47 in CTCs and PBMCs were analysed by qPCR. Their expression in high versus low CTC-positive patients with CRC was compared and clinicopathological correlations between these patient groups were analysed. CTCs were detected in 61% (38 of 62) of patients with CRC. The presence of higher numbers of CTCs was significantly correlated with advanced cancer stages (p = 0.045) and the subtypes of adenocarcinoma (conventional vs. mucinous, p = 0.019), while being weakly correlated with tumour size (p = 0.051). Patients with lower numbers of CTCs had higher expression of KRAS. Higher KRAS expression in CTCs was negatively correlated with tumour perforation (p = 0.029), lymph node status (p = 0.037), distant metastasis (p = 0.046) and overall staging (p = 0.004). CTLA-4 was highly expressed in both CTCs and PBMCs. In addition, CTLA-4 expression was positively correlated with KRAS (r = 0.6878, p = 0.002) in the enriched CTC fraction. Dysregulation of KRAS in CTCs might evade the immune system by altering the expression of CTLA-4, providing new insights into the selection of therapeutic targets at the onset of the disease. Monitoring CTCs counts, as well as gene expression profiling of PBMCs, can be helpful in predicting tumour progression, patient outcome and treatment.

Clinical application and detection techniques of liquid biopsy in gastric cancer

Gastric cancer (GC) is one of the most common tumors worldwide and the leading cause of tumor-related mortality. Endoscopy and serological tumor marker testing are currently the main methods of GC screening, and treatment relies on surgical resection or chemotherapy. However, traditional examination and treatment methods are more harmful to patients and less sensitive and accurate. A minimally invasive method to respond to GC early screening, prognosis monitoring, treatment efficacy, and drug resistance situations is urgently needed. As a result, liquid biopsy techniques have received much attention in the clinical application of GC. The non-invasive liquid biopsy technique requires fewer samples, is reproducible, and can guide individualized patient treatment by monitoring patients' molecular-level changes in real-time. In this review, we introduced the clinical applications of circulating tumor cells, circulating free DNA, circulating tumor DNA, non-coding RNAs, exosomes, and proteins, which are the primary markers in liquid biopsy technology in GC. We also discuss the current limitations and future trends of liquid biopsy technology as applied to early clinical biopsy technology.

Synergistic diagnostic value of circulating tumor cells and tumor markers CEA/CA19-9 in colorectal cancer

BACKGROUND

Circulation tumor cells (CTCs) play a crucial role in cancer spread and have a strong correlation with cancer progression. Previous works of research have shown that the number of CTCs can be used to predict the recurrence of colorectal cancer (CRC).

METHODS

In this study, we used the Cyttel method to isolate and detect CTCs, and analyzed their correlation with carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) levels.

RESULTS

We found that the amount and positive (CTC number ≥2 in 3.2 mL peripheral blood) rate of CTCs were higher in peripheral blood (PB) of patients in stage III/IV than that of patients in stage I/II, suggesting the number of CTCs in CRC patients may have a higher correlation with metastasis. Furthermore, the number of CTCs was correlated to CEA and CA19-9 levels in individuals with all stages of CRC, and all of them predicted a worse prognosis and higher recurrence rate. Notably, triple positive (CTCs ≥ 2, CEA ≥ 5 ng/mL, CA19-9 ≥ 37 U/mL in PB) leads to the worst outcome indicated by overall survival and recurrence rate.

CONCLUSION

Taken together, this study first revealed that a triple combination of CTCs, which were detected by the Cyttel method but not other approaches, CEA and CA19-9 is a promising prognostic marker on the recurrence of colorectal cancer and overall survival in clinic practice.

Advances in the Biology, Detection Techniques, and Clinical Applications of Circulating Tumor Cells

Circulating tumor cells (CTCs) play a crucial role in tumor recurrence and metastasis, and their early detection has shown remarkable benefits in clinical theranostics. However, CTCs are extremely rare, thus detecting them in the blood is very challenging. New CTC detection techniques are continuously being developed, enabling deeper analysis of CTC biology and potential clinical application. This article reviews current CTC detection techniques and their clinical application. CTCs have provided, and will continue to provide, important insights into the process of metastasis, which could lead to development of new therapies for different cancers.

Ulex Europaeus Agglutinin-I-Based Magnetic Isolation for the Efficient and Specific Capture of SW480 Circulating Colorectal Tumor Cells

The efficient and specific capture of circulating tumor cells (CTCs) from patients' peripheral blood is of significant value in precise cancer diagnosis and cancer therapy. As fine targeting molecules, lectins can recognize cancer cells specifically due to the abnormal glycosylation of molecules on the cancer cell membrane and the specific binding of lectin with glycoconjugates. Herein, a Ulex europaeus agglutinin-I (UEA-I)-based magnetic isolation strategy was developed to efficiently and specifically capture α-1,2-fucose overexpression CTCs from colorectal cancer (CRC) patients' peripheral blood. Using UEA-I-modified Fe₃O₄ magnetic beads (termed MB-UEA-I), up to 94 and 89% of target cells (i.e., SW480 CRC cells) were captured from the cell spiking complete cell culture medium and whole blood, respectively. More than 90% of captured cells show good viability and proliferation ability without detaching from MB-UEA-I. In combination with three-color immunocytochemistry (ICC) identification, MB-UEA-I has been successfully used to capture CTCs from CRC patients' peripheral blood. The experimental results indicate a correlation between CTC characterization and tumor metastasis. Specifically, MB-UEA-I can be applied to screen early CRC by capturing CTCs when served as a liquid biopsy. The presented work offers a new insight into developing cost-effective lectin-functionalized methods for biomedical applications.

Predictive Value of Circulating Tumor Cells Based on Subtraction Enrichment for Recurrence Risk in Stage II Colorectal Cancer

Current guidelines recommend adjuvant chemotherapy (ACT) for stage II colorectal cancer (CRC) patients by using clinical high risk factors, with which circulating tumor cells (CTCs) were not considered. Here, an assessment to detect CTCs based on subtraction enrichment mediated by magnetic beads conjugated with CD45, immunofluorescence staining of CK, and fluorescence in situ hybridization of CEP8 is established. Both CEP8- and CK-positive CTCs have the potential to improve the risk stratification of stage II CRC patients. Patients with preoperative CTCs of ≥4 had a significantly higher recurrence risk than those with preoperative CTCs of <4 in two external validation cohorts (P < 0.0001). In the subgroup with clinical high risk, when preoperative CTCs were <4, patients did not benefit from ACT (P = 0.5764); however, when preoperative CTCs were ≥4, patients received benefit from ACT (P = 0.0064). Additionally, regardless of clinical risk status and preoperative CTC levels, if postoperative CTC levels were ≥4 for more than three consecutive time points (monitoring time interval, 2-6 months), the recurrence rate was 100%. Our findings suggested that the subtraction enrichment of CTCs could provide a reliable method to stratify the recurrence risk and make therapeutic decisions after surgery in stage II CRC patients.

Diagnostic and prognostic biomarkers in colorectal cancer and the potential role of exosomes in drug delivery

Colorectal cancer (CRC) is third most common cancer with second most common cause of death worldwide. One fourth to one fifth of the CRC cases are detected at advance stage. Early detection of colorectal cancer might help in decreasing mortality and morbidity worldwide. CRC being a heterogeneous disease, new non-invasive approaches are needed to complement and improve the screening and management of CRC. Reliable and early detectable biomarkers would improve diagnosis, prognosis, therapeutic responses, and will enable the prediction of drug response and recurrence risk. Over the past decades molecular research has demonstrated the potentials of CTCs, ctDNAs, circulating mRNA, ncRNAs, and exosomes as tumor biomarkers. Non-invasive screening approaches using fecal samples for identification of altered gut microbes in CRC is also gaining attention. Exosomes can be potential candidates that can be employed in the drug delivery system. Further, the integration of in vitro, in vivo and in silico models that involve CRC biomarkers will help to understand the interactions occurring at the cellular level. This review summarizes recent update on CRC biomarkers and their application along with the nanoparticles followed by the application of organoid culture in CRC.

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.

Predictive Efficacy of Circulating Tumor Cells in First Drainage Vein Blood from Patients with Colorectal Cancer liver Metastasis

Circulating tumor cells (CTCs) are associated with metastasis. However, the low rate of detection of CTCs in peripheral vein blood (PVB) limits their clinical application. In this study, we observed higher positive rates of CTC in first drainage vein blood (FDVB) relative to peripheral venous blood (P < 0.001). Moreover, the CTC content was related to liver metastasis, T stage and CA19-9 levels. Our collective data suggest that CTCs in FDVB have good predictive utility for risk of liver metastasis of colorectal cancer (CRC), in particular, metachronous liver metastasis.

Efficient capture of circulating tumor cells with low molecular weight folate receptor-specific ligands

Retrieval of circulating tumor cells (CTC) has proven valuable for assessing a patient's cancer burden, evaluating response to therapy, and analyzing which drug might treat a cancer best. Although most isolation methods retrieve CTCs based on size, shape, or capture by tumor-specific antibodies, we explore here the use of small molecule tumor-specific ligands linked to magnetic beads for CTC capture. We have designed folic acid-biotin conjugates with different linkers for the capture of folate receptor (FR) + tumor cells spiked into whole blood, and application of the same technology to isolate FR + CTCs from the peripheral blood of both tumor-bearing mice and non-small cell lung patients. We demonstrate that folic acid linked via a rigid linker to a flexible PEG spacer that is in turn tethered to a magnetic bead enables optimal CTC retrieval, reaching nearly 100% capture when 100 cancer cells are spiked into 1 mL of aqueous buffer and ~ 90% capture when the same quantity of cells is diluted into whole blood. In a live animal model, the same methodology is shown to efficiently retrieve CTCs from tumor-bearing mice, yielding cancer cell counts that are proportional to total tumor burden. More importantly, the same method is shown to collect ~ 29 CTCs/8 mL peripheral blood from patients with non-small cell lung cancer. Since the ligand-presentation strategy optimized here should also prove useful in targeting other nanoparticles to other cells, the methods described below should have general applicability in the design of nanoparticles for cell-specific targeting.

Liquid biopsy in colorectal cancer: No longer young, but not yet old

Colorectal cancer (CRC) is one of the most prevalent cancers and the second leading cause of cancer-related deaths worldwide. The treatment strategy employed in CRC patients is becoming highly dependent on molecular characteristics present at diagnosis and during treatment. Liquid biopsy is an emerging field in the management of this cancer, and its relevance as a potential diagnostic, prognostic, monitoring, and therapeutic tool makes it a viable strategy in the clinical management of CRC patients. Liquid biopsy also has certain limitations, but these limitations seem to be at the reach of near-future technological development. In this letter, we focus on the clinical perspectives of liquid biopsy in CRC with particular regard to the various biomarkers recently identified that have been shown to be potentially useful in multiple aspects of early stage or metastatic CRC.

Discriminating Epithelial to Mesenchymal Transition Phenotypes in Circulating Tumor Cells Isolated from Advanced Gastrointestinal Cancer Patients

Gastrointestinal (GI) cancers constitute a group of highest morbidity worldwide, with colorectal cancer (CRC) and gastric cancer being among the most frequently diagnosed. The majority of gastrointestinal cancer patients already present metastasis by the time of diagnosis, which is widely associated with cancer-related death. Accumulating evidence suggests that epithelial-to-mesenchymal transition (EMT) in cancer promotes circulating tumor cell (CTCs) formation, which ultimately drives metastasis development. These cells have emerged as a fundamental tool for cancer diagnosis and monitoring, as they reflect tumor heterogeneity and the clonal evolution of cancer in real-time. In particular, EMT phenotypes are commonly associated with therapy resistance. Thus, capturing these CTCs is expected to reveal important clinical information. However, currently available CTC isolation approaches are suboptimal and are often targeted to capture epithelial CTCs, leading to the loss of EMT or mesenchymal CTCs. Here, we describe size-based CTCs isolation using the RUBYchip™, a label-free microfluidic device, aiming to detect EMT biomarkers in CTCs from whole blood samples of GI cancer patients. We found that, for most cases, the mesenchymal phenotype was predominant, and in fact a considerable fraction of isolated CTCs did not express epithelial markers. The RUBYchip™ can overcome the limitations of label-dependent technologies and improve the identification of CTC subpopulations that may be related to different clinical outcomes.

Protective effects of physical activity in colon cancer and underlying mechanisms: A review of epidemiological and biological evidence

Numerous epidemiological studies indicate that physical activity has a protective effect against colon cancer development and progression. Further, the relevant biological mechanisms where physical activity or exercise may improve survival have also been initially examined. In this review, we provide an overview of the epidemiological evidence to date which comprises 16 cohort studies of the effects of physical activity on colon cancer outcomes including cancer recurrence, cancer-specific and overall survival. Moreover, we present four potential mechanisms involving shear pressure, systemic milieu alteration, extracellular vesicles, and immune function by which physical activity and exercise may favorably impact colon cancer. Research currently in progress will provide definitive evidence of survival benefits resulting from exercise and future work will help clarify the role of targeted exercise and the relevant mechanisms involved.

Optimal Strategy for Colorectal Cancer Patients' Diagnosis Based on Circulating Tumor Cells and Circulating Tumor Endothelial Cells by Subtraction Enrichment and Immunostaining-Fluorescence In Situ Hybridization Combining with CEA and CA19-9

Background

Cancerous embryo antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) are commonly used in clinical practice to assist in diagnosing CRC. However, their sensitivity is very low. This study aims to investigate the clinical significance of circulating tumor cells (CTCs) and circulating tumor endothelial cells (CTECs) compared with CEA and CA19-9 in the auxiliary diagnosis of colorectal cancer (CRC) patients.

Methods

115 pathologically confirmed CRC patients and 20 healthy controls were enrolled in this study. CTCs and CTECs were enriched and identified by subtraction enrichment and immunostaining-fluorescence in situ hybridization (SE-iFISH). A logistic regression was used to establish a model for the receiver-operating characteristic (ROC) curve analysis, and the diagnostic efficacy of CTCs, CTECs, CEA, CA19-9, and their combinations was analyzed.

Results

The CTC (P < 0.0001) and CTEC (P=0.0009) level was significantly higher in CRC patients than that in healthy controls. For CRC patients, CTC and CTEC level was significantly correlated with tumor stage and lymph node metastasis status, but not with sex, age, tumor location, and degree of differentiation. The positive rate of CTCs, CTECs, CEA, and CA19-9 in CRC patients was 87.8%, 39.1%, 28.7%, and 26.1%, respectively. To distinguish CRC patients from controls, the area under the curve (AUC) of CTC was 0.889, which was much higher than 0.695 of CTEC, 0.696 of CEA, and 0.695 of CA19-9. Establishing ROC curve by logistic regression algorithm, the highest AUC was 0.935, which combined CTCs with CTEC, CEA, and CA19-9.

Conclusions

CTCs combined with CTEC, CEA, and CA19-9 are useful to improve the diagnostic efficiency, which has high clinical significance in the diagnosis of colorectal cancer.

Clinical significance of circulating tumour cells and tumour marker detection in the chemotherapeutic evaluation of advanced colorectal cancer

AIM

Systemic chemotherapy combining biological targeted therapies is the standard therapy for patients with metastatic colorectal cancer (mCRC), but effective markers are needed to identify clinical responders. Circulating tumour cells (CTCs) have been associated with prognosis in patients with mCRC. This study aimed to explore the relationship between CTC number and the clinical response of patients with advanced CRC.

METHOD

Epithelial cell adhesion molecule-independent enrichment and CD45^- fluorescence in situ hybridization immunofluorescence were used to detect peripheral blood CTCs in 79 patients with advanced CRC. Fisher's exact test and Spearman's rank correlation coefficient were used to analyse the correlation between CTC number and efficacy of chemotherapy. Kaplan-Meier and Cox regression analyses were used to evaluate progression-free survival (PFS).

RESULTS

Among the evaluable patients, CTCs were significantly correlated with clinical response (r =4.891, p = 0.031). High CTC numbers were associated with a poor treatment response (r = -0.250, p = 0.027). Dynamic decrease in CTC number was associated with clinical response (p = 0.046). High baseline CTC number and carcinoembryonic antigen levels were prognostic factors for unfavourable PFS in multivariable analysis [hazard ratio (HR) = 3.30, p = 0.011 and HR = 2.04, p = 0.044, respectively]. Compared with the CTC-positive group, the CTC-negative group showed superior PFS (median PFS 15.53 vs. 9.43 months, p = 0.041) among CRC patients receiving first-line treatment.

CONCLUSION

CTC number is a feasible biomarker for predicting outcomes in mCRC patients receiving systemic chemotherapy.

Detection of circulating tumour cells in colorectal cancer: Emerging techniques and clinical implications

Despite several advances in oncological management of colorectal cancer, morbidity and mortality are still high and devastating. The diagnostic evaluation by endoscopy is cumbersome, which is uncomfortable to many. Because of the intra- and inter-tumour heterogeneity and changing tumour dynamics, which is continuous in nature, the diagnostic biopsy and assessment of the pathological sample are difficult and also not adequate. Late manifestation of the disease and delayed diagnosis may lead to relapse or metastases. One of the keys to improving the outcome is early detection of cancer, ease of technology to detect with uniformity, and its therapeutic implications, which are yet to come. "Liquid biopsy" is currently the most recent area of interest in oncology, which may provide important tools regarding the characterization of the primary tumour and its metastasis as cancer cells shed into the bloodstream even at the early stages of the disease. By using this approach, clinicians may be able to find out information about the tumour at a given time. Any of the following three types of sampling of biological material can be used in the "liquid biopsy". These are circulating tumour cells (CTCs), circulating tumour DNA, and exosomes. The most commonly studied amongst the three is CTCs. CTCs with their different applications and prognostic value has been found useful in colorectal cancer detection and therapeutics. In this review, we will discuss various markers for CTCs, the core tools/techniques for detection, and also important findings of clinical studies in colorectal cancer and its clinical implications.

Improvement in immune dysfunction after FOLFOX chemotherapy for Stage III colon cancer is associated with improved minimal residual disease prognostic subtype and outcome

AIM

Minimal residual disease (MRD) is the net result of the biological properties of disseminated tumour cells and the effect of the immune system and treatment to eliminate them. The aim of this work is to report the changes in MRD status and immune function (lymphocyte count) after FOLFOX chemotherapy, and the outcome in Stage III colon cancer patients.

METHOD

This study is a prospective, single-centre observational study. Lymphocyte counts were determined prior to and 1, 2 and 3 months after the completion of chemotherapy. Circulating tumour cells (CTCs) and bone marrow micrometastases were determined using immunocytochemistry with anticarcinoembryonic antigen prior to and 1 month after chemotherapy. MRD was classified as negative (Group I), micrometastasis positive only (Group II) and CTC positive (Group III). Changes in lymphocyte counts and MRD subtype following chemotherapy and relapse-free progression were analysed.

RESULTS

Of the total of 185 patients, 83 (44.9%) relapsed. The risk of relapse significantly increased from Groups I to III (p < 0.001) and with decreasing lymphocyte count (p < 0.01). The lymphocyte count significantly decreased from Groups I to III (p < 0.001). Multivariance Cox regression analysis showed hazard ratios of 3.58 (Group II), 17.43 (Group III) and 0.39 (lymphocyte count) in predicting relapse. Following chemotherapy, improved lymphocyte count was associated with improved MRD subtype (p < 0.0001). Neither baseline lymphocyte count nor MRD subtype predicted response to chemotherapy. Five-year relapse-free survival for combined lymphocyte-MRD subtypes was 95%, 57% and 5% for Groups I to III, respectively (p < 0.001).

CONCLUSION

Following chemotherapy, improvements in immune function were associated with improved MRD subtype and a better relapse-free survival.

Liquid biopsy in chronic liver disease

Chronic liver diseases account for a considerable toll of incapacities, suffering, deaths, and resources of the nation's health systems. They can be prevented, treated or even cured when the diagnosis is made on time. Traditional liver biopsy remains the gold standard to diagnose liver diseases, but it has several limitations. Liquid biopsy is emerging as a superior alternative to surgical biopsy given that it surpasses the limitations: it is more convenient, readily and repeatedly accessible, safe, cheap, and provides a more detailed molecular and cellular representation of the individual patient's disease. Progress in understanding the molecular and cellular bases of diseased tissues and organs that normally release cells and cellular components into the bloodstream is catapulting liquid biopsy as a source of biomarkers for diagnosis, prognosis, and prediction of therapeutic response, thus supporting the realization of the promises of precision medicine. The review aims to summarize the evidence of the usefulness of liquid biopsy in liver diseases, including the presence of different biomarkers as circulating epithelial cells, cell-free nucleic acids, specific species of DNA and RNA, and the content of extracellular vesicles.

Circulating Tumor Cells (CTCs): A Unique Model of Cancer Metastases and Non-invasive Biomarkers of Therapeutic Response

Late-stage cancer metastasis remains incurable in the clinic and is the major cause death in patients. Circulating tumor cells (CTCs) are thought to be metastatic precursors shed from the primary tumor or metastatic deposits and circulate in the blood. The molecular network regulating CTC survival, extravasation, and colonization in distant metastatic sites is poorly defined, largely due to challenges in isolating rare CTCs. Recent advances in CTC isolation and ex vivo culture techniques facilitates single-cell omics and the development of related animal models to study CTC-mediated metastatic progression. With these powerful tools, CTCs can potentially be used as non-invasive biomarkers predicting therapeutic response. These studies may open a new avenue for CTC-specific drug discoveries. In this short review, we aim to summarize recent progress in the characterization of CTCs and their clinical relevance in various cancers, setting the stage for realizing personalized therapies against metastases.

Monitoring of circulating epithelial tumor cells using the Maintrac® method and its potential benefit for the treatment of patients with colorectal cancer

Circulating tumor cells are an important link between primary tumors and metastases. A longitudinal monitoring of their numbers and properties can provide valuable information on therapy response and disease progression for patients with colorectal cancer. As several techniques for the detection of circulating tumor cells are notorious for yielding low detection rates in patients with non-metastatic colorectal cancer, the present study aimed to perform a proof-of-principle study using the Maintrac^® approach for an assessment of circulating epithelial tumor cells (CETCs) in patients with colorectal cancer receiving neoadjuvant and/or adjuvant radio/chemotherapy (R/CT). CETCs in the peripheral blood of 22 patients with colorectal cancer were quantified by fluorescence image analysis (Maintrac^®) before and after the first cycle of a neoadjuvant and/or adjuvant R/CT, as well as before and after surgical resection of the primary tumor. To determine that blood-borne CETCs originate from tumor tissues, spheres were cultured from CETCs as well as from primary tumor tissue and compared with the expression of tumor-specific antigens. Within the scope of this study, it was demonstrated that the Maintrac^® method allows for the precise detection and characterization of CETCs in the blood of patients with colorectal cancer independent of tumor stage. Furthermore, correlations between CETC parameters and patients' response to neoadjuvant and/or adjuvant R/CT that have been described in previous literature could be reproduced. Whether the observed trends are of a general nature and suitable as an auxiliary criterion for prognosis and treatment decisions remains to be shown. Patients with rectal cancer may benefit from CETC monitoring as a method to select suitable patients for adjuvant therapy.

Circulating Biomarkers of Colorectal Cancer (CRC)-Their Utility in Diagnosis and Prognosis

The global burden of colorectal cancer (CRC) is expected to increase, with 2.2 million new cases and 1.1 million annual deaths by 2030. Therefore, the establishment of novel biomarkers useful in the early diagnosis of CRC is of utmost importance. A number of publications have documented the significance of the overexpression of several specific proteins, such as inflammatory mediators, in CRC progression. However, little is known about the potential utility of these proteins as circulating blood tumor biomarkers of CRC. Therefore, in the present review we report the results of our previous original studies as well as the findings of other authors who investigated whether inflammatory mediators might be used as novel biomarkers in the diagnosis and prognosis of CRC. Our study revealed that among all of the tested proteins, serum M-CSF, CXCL-8, IL-6 and TIMP-1 have the greatest value in the diagnosis and progression of CRC. Serum TIMP-1 is useful in differentiating between CRC and colorectal adenomas, whereas M-CSF and CRP are independent prognostic factors for the survival of patients with CRC. This review confirms the promising significance of these proteins as circulating biomarkers for CRC. However, due to their non-specific nature, further validation of their sensitivity and specificity is required.

Highly Correlated Recurrence Prognosis in Patients with Metastatic Colorectal Cancer by Synergistic Consideration of Circulating Tumor Cells/Microemboli and Tumor Markers CEA/CA19-9

Circulation tumor cells (CTCs) play an important role in metastasis and highly correlate with cancer progression; thus, CTCs could be considered as a powerful diagnosis tool. Our previous studies showed that the number of CTCs could be utilized for recurrence prediction in colorectal cancer (CRC); however, the odds ratio was still lower than five. To improve prognosis in CRC patients, we analyzed CTC clusters/microemboli, CTC numbers, and carcinoembryonic antigen (CEA)/carbohydrate antigen 19-9 (CA19-9) levels using a self-assembled cell array (SACA) chip system for recurrence prediction. In CRC patients, the presence of CTC clusters/microemboli may have higher correlation in metastasis when compared to the high number of CTCs. Additionally, when both the number of CTCs and serum CEA levels are high, very high odds ratios of 24.4 and 17.1 are observed in patients at all stages and stage III of CRC, respectively. The high number of CTCs and CTC clusters/microemboli simultaneously suggests the high chance of relapse (odds ratio 8.4). Overall, the characteristic of CTC clusters/microemboli, CEA level, and CTC number have a clinical potential to enhance CRC prognosis.

Early Dissemination of Circulating Tumor Cells: Biological and Clinical Insights

Circulating tumor cells (CTCs) play a causal role in the development of metastasis, the major cause of cancer-associated mortality worldwide. In the past decade, the development of powerful cellular and molecular technologies has led to a better understanding of the molecular characteristics and timing of dissemination of CTCs during cancer progression. For instance, genotypic and phenotypic characterization of CTCs, at the single cell level, has shown that CTCs are heterogenous, disseminate early and could represent only a minor subpopulation of the primary tumor responsible for disease relapse. While the impact of molecular profiling of CTCs has not yet been translated to the clinic, CTC enumeration has been widely used as a prognostic biomarker to monitor treatment response and to predict disease relapse. However, previous studies have revealed a major challenge: the low abundance of CTCs in the bloodstream of patients with cancer, especially in early stage disease where the identification and characterization of subsequently "lethal" cells has potentially the greatest clinical relevance. The CTC field is rapidly evolving with development of new technologies to improve the sensitivity of CTC detection, enumeration, isolation, and molecular profiling. Here we examine the technical and analytical validity of CTC technologies, we summarize current data on the biology of CTCs that disseminate early and review CTC-based clinical applications.

Liquid Biopsy for Prognosis and Treatment in Metastatic Colorectal Cancer: Circulating Tumor Cells vs Circulating Tumor DNA

Liquid biopsy recently gained widespread attention as a noninvasive alternative/complementary technique to tissue biopsy in patients with cancer. As technological advances have improved both feasibility and turnaround time, liquid biopsy has expanded tumor molecular analysis with acknowledgement of both spatial and temporal heterogeneity, overcoming many limitations of traditional tissue biopsy. Because of its diagnostic, prognostic, and predictive value, liquid biopsy has been extensively studied also in metastatic colorectal cancer. Indeed, as personalized medicine establishes its role in cancer treatment, genetic biomarkers unveiling the emergence of early resistance are needed. Among the wide variety of tumor analytes amenable to collection, circulating DNA and circulating tumor cells are the most adopted approaches, and both carry clinical relevance in colorectal cancer. However, few studies focused on comparing feasibility between these two approaches. In this review, we discuss the potential implications of liquid biopsy in metastatic colorectal cancer, assessing the advantages and drawbacks of circulating DNA and circulating tumor cells, and highlighting the most relevant trials for clinical practice.

5'-tRF-GlyGCC: a tRNA-derived small RNA as a novel biomarker for colorectal cancer diagnosis

BACKGROUND

tRNA-derived small RNAs (tDRs), which are widely distributed in human tissues including blood and urine, play an important role in the progression of cancer. However, the expression of tDRs in colorectal cancer (CRC) plasma and their potential diagnostic values have not been systematically explored.

METHODS

The expression profiles of tDRs in plasma of CRC and health controls (HCs) are investigated by small RNA sequencing. The level and diagnostic value of 5'-tRF-GlyGCC are evaluated by quantitative PCR in plasma samples from 105 CRC patients and 90 HCs. The mechanisms responsible for biogenesis of 5'-tRF-GlyGCC are checked by in vitro and in vivo models.

RESULTS

5'-tRF-GlyGCC is dramatically increased in plasma of CRC patients compared to that of HCs. The area under curve (AUC) for 5'-tRF-GlyGCC in CRC group is 0.882. The combination of carcinoembryonic antigen (CEA) and carbohydrate antigen 199 (CA199) with 5'-tRF-GlyGCC improves the AUC to 0.926. Consistently, the expression levels of 5'-tRF-GlyGCC in CRC cells and xenograft tissues are significantly greater than that in their corresponding controls. Blood cells co-cultured with CRC cells or mice xenografted with CRC tumors show increased levels of 5'-tRF-GlyGCC. In addition, we find that the increased expression of 5'-tRF-GlyGCC is dependent on the upregulation of AlkB homolog 3 (ALKBH3), a tRNA demethylase which can promote tRNA cleaving to generate tDRs.

CONCLUSIONS

The level of 5'-tRF-GlyGCC in plasma is a promising diagnostic biomarker for CRC diagnosis.

CD30+OX40+ Treg is associated with improved overall survival in colorectal cancer

Regulatory T cells (Tregs) are often enriched in tumors, where their immunosuppressive function has a key role in tumor persistence and progression. In colorectal cancer (CRC), however, Tregs are frequently associated with an improved clinical outcome. Tumor-infiltrating Tregs have been shown to exhibit a distinct signature comprising the co-stimulatory molecules (OX40, 4-1BB), cytokine receptors (IL1R2, IL21R, CCR8, CD30), and co-inhibitory molecules (PD-L1, TIGIT). Here, we showed by flow cytometry that circulating CD45RO⁺ Tregs from patients with CRC (n = 25) have elevated CD30 and OX40 expression compared to healthy subjects (n = 14). We identified co-expression of CD30 and OX40 on circulating CD45RO⁺ Tregs using single-cell images captured by the DEPArray^™ system. The frequency of CD30⁺OX40⁺CD45RO⁺ Tregs was significantly higher in CRC patients than in healthy subjects (P < 0.001). Importantly, receiver operating characteristic analysis confirmed that this CD30⁺OX40⁺ Treg subset could strongly discriminate between CRC patients and healthy subjects with the highest accuracy of 92.3%, an AUC of 0.92, a sensitivity of 88%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 82.35%, and a trade-off value of 3.44%, compared to other Treg subsets. Consistently, multiplex-IHC/IF of tumor-infiltrating Tregs revealed a significant association between high densities of CD30⁺OX40⁺ Tregs and improved overall survival; no such association was found for other subsets. These data suggest a potential role for CD30⁺OX40⁺ Tregs as a diagnostic or prognostic biomarker in CRC.

Macrophages mediate colon carcinoma cell adhesion in the rat liver after exposure to lipopolysaccharide

The surgical resection of primary colorectal cancer is associated with an enhanced risk of liver metastases. Moreover, bacterial translocation or anastomic leakage during resection has been shown to correlate with a poor long-term surgical outcome, suggesting that bacterial products may contribute to the formation of metastases. Driven by these premises, we investigated the role of the bacterial product lipopolysaccharide (LPS) in the generation of liver metastases. Intraperitoneal injection of LPS led to enhanced tumor-cell adhesion to the rat liver as early as 1.5 h post-administration. Furthermore, a rapid loss of the expression of the tight junction protein zonula occludens-1 (ZO-1) was observed, suggesting that LPS disrupts the integrity of the microvasculature. LPS addition to endothelial-macrophage co-cultures damaged endothelial monolayers and caused the formation of intercellular gaps, which was accompanied by increased tumor-cell adhesion. These results suggest that macrophages are involved in the endothelial damage resulting from exposure to LPS. Interestingly, the expression levels of of ZO-1 were not affected by LPS treatment in rats in which liver macrophages had been depleted as well as in rats that had been treated with a reactive oxygen species (ROS) scavenger. In both settings, decreased tumor-cell adhesion was observed. Taken together, our findings indicate that LPS induces ROS release by macrophages, resulting in the damage of the vascular lining of the liver and hence allowing increased tumor-cell adherence. Thus, peri-operative treatments that prevent the activation of macrophages and—as a consequence—limit endothelial damage and tumor-cell adhesion may significantly improve the long-term outcome of cancer patients undergoing surgical tumor resection.

Assessment of circulating tumor cells in peripheral blood using flow cytometry in patients with surgery for colorectal cancer – review

Introduction: Colorectal cancer (CRC) is the third most common neoplasia in the world. Circulating tumor cells (CTC) have a prognostic value and can be useful in monitoring solid neoplasia. Only one method for CTC identification has received the approval and this is the CellSearch® system based on the immunomagnetic separation. Multiple markers are used in CTC identification, as epithelial markers and cytokeratines. CTC identification in peripheral blood is associated with a worse prognostic and reduced free survival in CRC.

Material and methods: We performed a systematic search in PubMed database for articles that reports the circulating tumor cells in CRC until July 2019. We selected studies in English and French and the main words used for search were ‘circulating tumor cells’, ‘colorectal cancer’, ‘colon cancer’, ‘rectal cancer’, ‘flow cytometry’, ‘peripheral blood’. We included studies with more than 10 patients, where samples were collected from the blood in relation with surgery and flow cytometry was used as analyzing technique.

Results: We included 7 studies in final analysis, that showed in flow cytometry analysis a cut-off value of CTC that can vary from 2-4 CTC/ 7.5 ml peripheral blood with a sensitivity of 50.8% and specificity of 95%. Patients with positive CTC were associated with higher T stage and positive lymph nodes, with a worse overall survival (OS) and disease free survival (DFS) comparing with negative patients.

Conclusion: CTC are considered to be a prognostic factor who needs more validation studies in order to be included in the clinical practice.

Novel Circulating Tumor Cell Assay for Detection of Colorectal Adenomas and Cancer

OBJECTIVES

There is a significant unmet need for a blood test with adequate sensitivity to detect colorectal cancer (CRC) and adenomas. We describe a novel circulating tumor cell (CTC) platform to capture colorectal epithelial cells associated with CRC and adenomas.

METHODS

Blood was collected from 667 Taiwanese adults from 2012 to 2018 before a colonoscopy. The study population included healthy control subjects, patients with adenomas, and those with stage I-IV CRC. CTCs were isolated from the blood using the CellMax platform. The isolated cells were enumerated, and an algorithm was used to determine the likelihood of detecting adenoma or CRC. Nominal and ordinal logistic regression demonstrated that CTC counts could identify adenomas and CRC, including CRC stage.

RESULTS

The CellMax test demonstrated a significant association between CTC counts and worsening disease status (Cuzick's P value < 0.0001) with respect to the adenoma-carcinoma sequence. The test showed high specificity (86%) and sensitivity across all CRC stages (95%) and adenomatous lesions (79%). The area under the curve was 0.940 and 0.868 for the detection of CRC and adenomas, respectively.

DISCUSSION

The blood-based CTC platform demonstrated high sensitivity in detecting adenomas and CRC, as well as reasonable specificity in an enriched symptomatic patient population.

TRANSLATIONAL IMPACT

If these results are reproduced in an average risk population, this test has the potential to prevent CRC by improving patient compliance and detecting precancerous adenomas, eventually reducing CRC mortality.

Clinical Potential of Circulating Tumor Cells in Colorectal Cancer: A Prospective Study

Circulating tumor cells (CTCs) in the blood have been used as diagnostic markers in patients with colorectal cancer (CRC). In this study, we evaluated a CTC detection system based on cell size to assess CTCs and their potential as early diagnostic and prognostic biomarkers for CRC.

Clinical significance of epithelial-mesenchymal transition typing of circulating tumour cells in colorectal cancer

AIM

The aim was to determine the diagnostic value of epithelial-mesenchymal transition typing of circulating tumour cells (CTCs) in colorectal cancer (CRC).

METHOD

Peripheral blood samples were collected from 51 CRC patients before anti-tumour treatment from April 2016 to June 2018 at the Peking University Shenzhen Hospital. The blood samples were analysed using the CanPatrol CTC typing technique (SurExam, Guangzhou, China), which combines nanomembrane enrichment with mRNA in situ hybridization. Based on the marker expression, the CTCs were classified into epithelial, epithelial mesenchymal and mesenchymal (M-CTC) types. The correlation between the CTC counts and clinicopathological characteristics such as gender, age, TNM stage, lymph node metastasis and distant metastasis were analysed by univariate and multivariate Cox regression models. The overall survival and progression-free survival (PFS) of patients demarcated by CTC typing were analysed using the Kaplan-Meier method and log-rank tests.

RESULT

M-CTCs were detected more frequently in patients with lymph node metastasis (N2 81.8%; N1 72.7%; N0 38.9%) as well as distant metastasis (M0 50%; M1a 81.25%; M1b 85.7%) compared to those without metastasis. In addition, the presence of M-CTCs was significantly correlated with distant metastasis (P < 0.01). Univariate analysis showed that lymph node metastasis (P = 0.035), distant metastasis (P < 0.001) and total CTC count ≥ 4 (P = 0.007) and M-CTC count ≥ 1 (P < 0.001) were significantly associated with unfavourable PFS, and lymph node metastasis (P = 0.04), distant metastasis (P = 0.01) and M-CTC count ≥ 1 (P < 0.001) were significantly associated with unfavourable overall survival. Multivariate analysis showed that the presence of M-CTCs was the only independent prognostic factor for poor PFS, and patients with M-CTCs had significantly shorter PFS than those without (P = 0.011).

CONCLUSION

M-CTCs are significantly associated with CRC severity and metastasis, and M-CTC count is an independent predictor of prognosis.

Association Between Baseline Circulating Tumor Cells, Molecular Tumor Profiling, and Clinical Characteristics in a Large Cohort of Chemo-naïve Metastatic Colorectal Cancer Patients Prospectively Collected

BACKGROUND

Clinicopathologic characteristics and prognostic and predictive factors offer valuable guidance when selecting optimal first-line treatment in patients with metastatic colorectal cancer (CRC). The association between baseline circulating tumor cell (bCTC) count, molecular tumor profile, and clinicopathologic features was analyzed in a chemo-naïve metastatic CRC population.

PATIENTS AND METHODS

A total of 1202 patients from the Spanish VISNÚ-1 (FOLFIRINOX/bevacizumab vs. FOLFOX/bevacizumab) and VISNÚ-2 (FOLFIRI/bevacizumab vs. FOLFIRI/cetuximab; RAS-wildtype) studies were analyzed for mutational status and bCTC count. The association between clinicopathologic characteristics and bCTC count, mutational status, and microsatellite instability (MSI) was analyzed in 589 eligible patients.

RESULTS

Interestingly, 41% of the population studied presented ≥3 bCTC count. bCTC count ≥3 was associated with worse performance status (according Eastern Cooperative Oncology Group scale), stage IV at diagnosis, at least 3 metastatic sites, and elevated carcinoembryonic antigen (CEA) levels; but not with RAS or BRAF mutations or high MSI. BRAFmut (BRAF mutated) tumors were associated with right-sided primary tumors, peritoneum, distant lymph node metastasis, and less frequent liver involvement. RASmut (RAS mutated) was associated with worse performance status; stage IV at diagnosis; right-sided primary tumors; liver, lung, and bone metastases; at least 3 metastatic sites; and elevated CEA, whereas PIK3CAmut (PIK3CA mutated) tumors were associated with right-sided primary tumors, high CEA serum levels, and older age. High MSI was associated with right-sided primary tumors, distant lymph nodes metastasis, and lower CEA levels.

CONCLUSIONS

In our study, elevated bCTCs and RASmut were associated with clinicopathologic features known to be associated with poor prognosis; whereas the poor prognosis of BRAFmut tumors in chemo-naïve metastatic CRC is not explained by associations with poor clinicopathologic prognostic factors, except right-sided primary tumors.

TRIAL REGISTRATION NUMBER

VISNU 1 ClinicalTrials.gov ID: NCT01640405/ VISNU 2 ClinicalTrials.gov ID: NCT01640444.

Genetic Analysis of Circulating Tumour Cells

The classification of human cancers has traditionally relied on the tissue of origin, the histologic appearance and anatomical extent of disease, otherwise referred to as grade and stage. However, this system fails to explain the highly variable clinical behaviour seen for any one cancer. Molecular characterization through techniques such as next-generation sequencing (NGS) has led to an appreciation of the extreme genetic heterogeneity that underlies most human cancers. Because of the difficulties associated with fresh tissue biopsy, interest has increased in using circulating tumour material, such as circulating tumour cells (CTCs), as a non-invasive way to access tumour tissue. CTC enumeration has been demonstrated to have prognostic value in metastatic breast, colon and prostate cancers. Recent studies have also shown that CTCs are suitable material for molecular characterization, using techniques such as reverse transcription-polymerase chain reaction (RT-PCR), fluorescence in situ hybridization (FISH), array comparative genomic hybridization (aCGH) and NGS. Furthermore, genetic analysis of CTCs may be more suitable to study tumour heterogeneity and clonal evolution than fresh tissue biopsy. Whether blood-based biopsy techniques will be accepted as a replacement to fresh tissue biopsies remains to be seen, but there is reason for optimism. While significant barriers to this acceptance exist, blood-based biopsy techniques appear to be reliable and representative alternatives to fresh tissue biopsy.

Prognostic value of circulating tumour cells in limited-stage small-cell lung cancer: analysis of the concurrent once-daily versus twice-daily radiotherapy (CONVERT) randomised controlled trial

BACKGROUND

The clinical significance of circulating tumour cells (CTCs) in limited-stage small-cell lung cancer (LS-SCLC) is not well defined. We report a planned exploratory analysis of the prevalence and prognostic value of CTCs in LS-SCLC patients enrolled within the phase III randomised CONVERT (concurrent once-daily versus twice-daily chemoradiotherapy) trial.

PATIENTS AND METHODS

Baseline blood samples were enumerated for CTCs using CellSearch in 75 patients with LS-SCLC who were enrolled in the CONVERT trial and randomised between twice- and once-daily concurrent chemoradiation. Standard statistical methods were used for correlations of CTCs with clinical factors. Log-rank test and Cox regression analyses were applied to establish the associations of 2, 15 and 50 CTC thresholds with progression-free survival (PFS) and overall survival (OS). An optimal CTC count threshold for LS-SCLC was established.

RESULTS

CTCs were detected in 60% (45/75) of patients (range 0-3750). CTC count thresholds of 2, 15 and 50 CTCs all significantly correlate with PFS and OS. An optimal CTC count threshold in LS-SCLC was established at 15 CTCs, defining 'favourable' and 'unfavourable' prognostic risk groups. The median OS in <15 versus ≥15 CTCs was 26.7 versus 5.9 m (P = 0.001). The presence of ≥15 CTCs at baseline independently predicted ≤1 year survival in 70% and ≤2 years survival in 100% of patients.

CONCLUSION

We report the prognostic value of baseline CTC count in an exclusive LS-SCLC population at thresholds of 2, 15 and 50 CTCs. Specific to LS-SCLC, ≥15 CTCs was associated with worse PFS and OS independent of all other factors and predicted ≤2 years survival. These results may improve disease stratification in future clinical trial designs and aid clinical decision making.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00433563.

A temporary indwelling intravascular aphaeretic system for in vivo enrichment of circulating tumor cells

Circulating tumor cells (CTCs) have become an established biomarker for prognosis in patients with various carcinomas. However, current ex vivo CTC isolation technologies rely on small blood volumes from a single venipuncture limiting the number of captured CTCs. This produces statistical variability and inaccurate reflection of tumor cell heterogeneity. Here, we describe an in vivo indwelling intravascular aphaeretic CTC isolation system to continuously collect CTCs directly from a peripheral vein. The system returns the remaining blood products after CTC enrichment, permitting interrogation of larger blood volumes than classic phlebotomy specimens over a prolonged period of time. The system is validated in canine models showing capability to screen 1-2% of the entire blood over 2 h. Our result shows substantial increase in CTC capture, compared with serial blood draws. This technology could potentially be used to analyze large number of CTCs to facilitate translation of analytical information into future clinical decisions.

Enumerating Circulating Tumor Cells with a Self-Assembled Cell Array (SACA) Chip: A Feasibility Study in Patients with Colorectal Cancer

Colorectal cancer (CRC) is the second most common cause of cancer-related death worldwide. Detecting and enumerating circulating tumor cells (CTCs) in patients with colorectal cancer emerged as an important prognostic tool which provides a direct estimate of metastatic potential. Improving the turnaround time and decreasing sample volume is critical for incorporating this liquid biopsy tool into routine practice. The objective of the current study was to validate the clinical feasibility of a self-assembled cell array (SACA) chip, a CTC counting platform with less than 4 h turnaround time, in patients with newly diagnosed colorectal cancers. In total, 179 patients with newly diagnosed colorectal cancers from a single institute were enrolled. Epithelial cell adhesion molecule positive (EpCAM(+)), cluster of differentiation 45 negative (CD45(-)) cells were isolated and enumerated from 2 mL of peripheral vein blood (PB) and inferior mesenteric vein blood (IMV) samples obtained during surgery. We found that the CTC count in PB but not IMV correlates with disease stages. Neoadjuvant chemotherapy did not lead to decreased CTC count in both types of blood samples. With cutoffs of four CTCs per 2 mL of blood, and serum carcinoembryonic antigen (CEA) level of 5 ng/mL, patients with non-metastatic disease were more likely to experience recurrence if they had high PB CTC count and high serum CEA concentration (odds ratio, 8.9). Our study demonstrates the feasibility of enumerating CTCs with a SACA chip in patients with colorectal cancer.

Spillage of bacterial products during colon surgery increases the risk of liver metastases development in a rat colon carcinoma model

Surgical resection of the primary tumor provides the best chance of cure for patients with colorectal carcinoma (CRC). However, bacterial translocation during intestinal surgery has been correlated with poor long-term oncological outcome. Therefore, we investigated the influence of bacterial contamination during colon surgery on CRC liver metastases development. Blood and liver samples of patients undergoing resection of primary CRC or liver metastases were collected. Cell numbers, activation markers and inflammatory mediators were determined. Tumor cell adhesion and outgrowth after sham- or colectomy operations were determined in a rat model, in which tumor cells had been injected into the portal vein.

White blood cells and granulocytes were increased in per- and post-operative patient blood samples. IL-6 was also increased post-operatively compared to the preoperative level. Expression of NOX-2, NOX-4 and polymorphonuclear cells (PMNs) numbers were elevated in post-operative human liver samples. In vitro stimulation of macrophages with plasma of rats after colectomy resulted in production of reactive oxygen species (ROS). Colectomy in rats increased D-lactate levels in plasma, supporting bacterial translocation. Decreased expression of tight junction molecules and increased tumor cell adhesion and outgrowth was observed. Treatment with a selective decontamination of the digestive tract (SDD) cocktail decreased tumor cell adherence after colectomy.

In conclusion, postoperative bacterial translocation may activate liver macrophages and PMNs, resulting in ROS production. As we previously showed that ROS release led to liver vasculature damage, circulating tumor cells may adhere to exposed extracellular matrix and grow out into liver metastases. This knowledge is pivotal for development of therapeutic strategies to prevent surgery-induced liver metastases development.

Mesenchymal marker and LGR5 expression levels in circulating tumor cells correlate with colorectal cancer prognosis

PURPOSE

The presence of circulating tumor cells (CTCs) has been found to correlate with colorectal cancer (CRC) prognosis, whereas epithelial-mesenchymal transition (EMT) in CTCs has been found to be associated with CRC metastasis. LGR5 is a known target of Wnt signaling and plays an important role in CRC development. The aim of this study was to assess the clinical relevance of EMT and LGR5 expression in CTCs from CRC patients.

METHODS

Sixty-six CRC patients were included in this study. The detection and expression of EMT phenotypes in CTCs from these patients were assessed using CanPatrol™ CTC enrichment and mRNA in situ hybridization (ISH), respectively. LGR5 expression in the CTCs was assessed using mRNA ISH.

RESULTS

CTCs were detected in 86.4% (57/66) of the CRC patients included. Both the numbers of total CTCs and of CTCs displaying a mesenchymal phenotype (M+ CTCs) were found to significantly correlate with advanced disease stages and the occurrence of metastasis (p < 0.05). An adjusted multivariate analysis also indicated that the number of M+ CTCs significantly correlated with the occurrence of metastasis (p = 0.031). Additionally, we found that a high LGR5 expression level significantly correlated with the occurrence of metastasis (p < 0.05). We also found that the presence of ≥ 6 CTCs or ≥ 3 M+ CTCs per 5 ml blood significantly correlated with disease progression (p < 0.05). Patients with ≥ 6 CTCs or ≥ 3 M+ CTCs per 5 ml blood were found to exhibit poorer progression-free survival (PFS) and overall survival (OS) rates (p < 0.05 in all cases). Using Cox regression analyses, we found that only total CTC numbers remained as independent prognostic factors for a worse PFS (p = 0.043).

CONCLUSIONS

From our data we conclude that CTC numbers and EMT phenotypes may serve as prognostic markers for disease progression and metastasis in CRC patients. In addition, we conclude that LGR5 expression in CTCs may serve as a marker for CRC metastasis.

Cell-Free DNA Blood Collection Tubes Are Appropriate for Clinical Proteomics: A Demonstration in Colorectal Cancer

BACKGROUND

Optimized blood collection tubes (BCT) have been developed to expand the utility of plasma cell-free DNA (cfDNA) and are in clinical use. The appropriateness of plasma collected and stored in these tubes for proteomic analysis is unknown.

METHODS

Paired blood samples were collected in BCT and traditional K3EDTA (EDTA) tubes from healthy controls and from colorectal cancer (CRC) patients before and after surgery, and stored for between 45 min and 48 h at room temperature. Plasma proteins were analyzed following high-abundant plasma protein depletion in quantitative discovery and targeted proteomics by liquid chromatography tandem-mass spectrometry (LC-MS/MS).

RESULTS

BCT reduced cellular protein contamination in healthy controls over time, and increased the number of high confident low-abundant protein identifications in CRC blood samples compared to matched samples collected in EDTA tubes. The known CRC plasma protein biomarker, carcinoembryonic antigen (CEA), showed elevated levels across patients pre-operatively when collected and stored in BCT compared to EDTA tubes. Emerging CRC biomarkers, Dickkopf-3 (DKK3) and Gelsolin (GSN), showed elevated levels pre-operatively when collected in BCT.

CONCLUSIONS

Optimized BCT are appropriate for low-abundant plasma protein analysis and can be used with confidence for clinical proteomics.

Expression and clinical relevance of epithelial and mesenchymal markers in circulating tumor cells from colorectal cancer

Circulating tumor cells (CTCs) with phenotypic hallmarks of epithelial-mesenchymal transition (EMT) reportedly contribute to tumor metastasis in different cancer types. We therefore evaluated the expression of EMT markers in CTCs obtained from a large cohort of Chinese patients with colorectal cancer (CRC) and investigated their clinical relevance. The CanPatrol^TM CTC enrichment technique was used to isolate and classify CTCs. CTCs were detected in 1046 of 1203 patients (86.9%), and three phenotypes were identified based on the expression of epithelial and mesenchymal markers: epithelial CTCs, biophenotypic (epithelial/mesenchymal) CTCs, and mesenchymal CTCs. Total CTC numbers positively correlated with both clinical stage and lymph node metastasis and distant metastasis. Furthermore, both biophenotypic and mesenchymal, but not epithelial, CTCs, correlated with the above parameters, suggesting CTCs displaying a mesenchymal phenotype denote more aggressive disease and metastatic potential. This is the first study to demonstrate a significant correlation between CTCs displaying a mesenchymal phenotype and both clinical stage and metastasis in a large cohort of patients with CRC. Our findings suggest that assessment of not only epithelial, but also mesenchymal markers in CTC analyses may offer valuable assistance for tumor staging and metastasis evaluation in patients with CRC.

Enumeration and targeted analysis of KRAS, BRAF and PIK3CA mutations in CTCs captured by a label-free platform: Comparison to ctDNA and tissue in metastatic colorectal cancer

Treatment of advanced colorectal cancer (CRC) requires multimodal therapeutic approaches and need for monitoring tumor plasticity. Liquid biopsy biomarkers, including CTCs and ctDNA, hold promise for evaluating treatment response in real-time and guiding therapeutic modifications. From 15 patients with advanced CRC undergoing liver metastasectomy with curative intent, we collected 41 blood samples at different time points before and after surgery for CTC isolation and quantification using label-free Vortex technology. For mutational profiling, KRAS, BRAF, and PIK3CA hotspot mutations were analyzed in CTCs and ctDNA from 23 samples, nine matched liver metastases and three primary tumor samples. Mutational patterns were compared. 80% of patient blood samples were positive for CTCs, using a healthy baseline value as threshold (0.4 CTCs/mL), and 81.4% of captured cells were EpCAM+ CTCs. At least one mutation was detected in 78% of our blood samples. Among 23 matched CTC and ctDNA samples, we found a concordance of 78.2% for KRAS, 73.9% for BRAF and 91.3% for PIK3CA mutations. In several cases, CTCs exhibited a mutation that was not detected in ctDNA, and vice versa. Complementary assessment of both CTCs and ctDNA appears advantageous to assess dynamic tumor profiles.

Circulating tumor cells: A promising marker of predicting tumor response in rectal cancer patients receiving neoadjuvant chemo-radiation therapy

Purpose

The aim of this study was to investigate the role of circulating tumor cells (CTCs) in assessing and predicting tumor response to neoadjuvant chemoradiotherapy (CRT) for patients with locally advanced rectal cancer (LARC).

Methods

A total of 115 patients with T3-4 and/or N+ rectal cancer were enrolled. All patients received neoadjuvant CRT followed by radical surgery after 6-8 weeks. The pathological results after surgery were evaluated according to tumor regression grade (TRG) classification.

Results

Based on TRG score, patients were classified as responders (TRG3-4) and non-responders (TRG0-2). The baseline CTC counts of responders were significantly higher than those of non-responders (44.50±11.94 vs. 37.67±15.45, P=0.012). By contrast, the post-CRT CTC counts of responders were significantly lower than those of non-responders (3.61±2.90 vs. 12.08±7.40, P<0.001). According to ROC analysis, Δ%CTC (percentage difference in CTC counts between baseline and post-CRT) was identified as the stronger predictor to discriminate responders from non-responders (AUC: 0.860). The results of multivariate analysis also indicated that post-CRT CTC counts and Δ%CTC were significantly and independently associated with tumor response to CRT.

Conclusions

The detection of CTCs is a powerful and promising tool for evaluating and predicting responses to neoadjuvant CRT in LARC patients.