Circulating tumor cells criteria (CyCAR) versus standard RECIST criteria for treatment response assessment in metastatic colorectal cancer patients

Recombinant canstatin inhibits the progression of hepatocellular carcinoma by repressing the HIF-1α/VEGF signaling pathway

Hepatocellular carcinoma (HCC), a hypervascular tumor, is the most frequent primary malignant tumor of the liver. Angiogenesis inhibitors, such as endogenous angiogenesis inhibitors, are essential for HCC therapy and have generated significant interest owing to their safety, efficacy, and multitargeting attributes. Canstatin is an angiogenesis inhibitor derived from the basement membrane and exerts anti-tumor effects. However, the inhibitory effects and underlying mechanisms of action of canstatin on HCC remain unclear. Therefore, in this study, HepG2 and Huh7 cells were used to investigate the inhibitory effects of recombinant canstatin on HCC cells. Subsequently, the biosafety and inhibitory effects of recombinant canstatin on tumor growth were investigated in a xenograft animal model of liver cancer. Canstatin inhibited the growth of liver cancer cells by regulating their proliferation, apoptosis, and migration. Additionally, it suppressed the occurrence and progression of HCC by modulating the HIF-1α/VEGF signaling pathway. In mice, canstatin exerted no discernible harmful side effects and suppressed the growth of HCC subcutaneous xenograft tumors. Overall, our findings shed light on the molecular pathways underlying canstatin-induced HCC cell death that may help develop novel HCC treatments.

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.

The Challenge to Stabilize, Extract and Analyze Urinary Cell-Free DNA (ucfDNA) during Clinical Routine

BACKGROUND

The "Liquid Biopsy" has become a powerful tool for cancer research during the last decade. Circulating cell-free DNA (cfDNA) that originates from tumors has emerged as one of the most promising analytes. In contrast to plasma-derived cfDNA, only a few studies have investigated urinary cfDNA. One reason might be rapid degradation and hence inadequate concentrations for downstream analysis. In this study, we examined the stability of cfDNA in urine using different methods of preservation under various storage conditions.

METHODOLOGY

To mimic patient samples, a pool of healthy male and female urine donors was spiked with a synthetic cfDNA reference standard (fragment size 170 bp) containing the T790M mutation in the EGFR gene. Spiked samples were preserved with three different buffers and with no buffer over four different storage periods (0 h; 4 h; 12 h; 24 h) at room temperature vs. 4 °C. The preservatives used were Urinary Analyte Stabilizer (UAS, Novosanis, Wijnegem, Belgium), Urine Conditioning Buffer (UCB, Zymo, Freiburg, Germany) and a self-prepared buffer called "AlloU". CfDNA was extracted using the QIAamp MinElute ccfDNA Mini Kit (Qiagen, Hilden, Germany). CfDNA concentration was measured using the Qubit™ 4 fluorometer (Thermo Fisher Scientific, Waltham, MA, USA). Droplet digital PCR (ddPCR) was used for detection and quantification of the T790M mutation.

RESULTS

Almost no spiked cfDNA was recoverable from samples with no preservation buffer and the T790M variant was not detectable in these samples. These findings indicate that cfDNA was degraded below the detection limit by urinary nucleases. Stabilizing buffers showed varying efficiency in preventing this degradation. The most effective stabilizing buffer under all storage conditions was the UAS, enabling adequate recovery of the T790M variant using ddPCR.

CONCLUSION

From a technical point of view, stabilizing buffers and adequate storage conditions are a prerequisite for translation of urinary cfDNA diagnostics into clinical routine.

Circulating tumor cells in cancer-risk populations as a cancer interception tool

Cancer interception (CI) is a new approach to cancer prevention and treatment in a cancer-risk population that aims to detect and treat pre-tumoral stages. It has several potential advantages over traditional cancer diagnosis and monitoring methods because it is non-invasive, making it less painful and risky than conventional biopsy procedures. The circulating tumor cells (CTCs), liquid biopsy family members, are essential for the CI approach; then, the liquid biopsy (LB) is used as a CI tool. LB can be performed frequently because of its easy sampling and early pathological stages, which allow repeated non-invasive monitoring of cancer progression and response to treatment. CTCs have been found in the bloodstream of several types of cancer patients, including in early-stage cancer and premalignant lesions, suggesting a tumor development role in cancer's early stages. This chapter will present foundational scientific studies addressing CI and the clinical impact of CTC screening in a population at risk for cancer.

Predictive value of circulating tumor cell counts during the treatment of cancer: interactions with the blood microenvironment

OBJECTIVE

This study aimed to evaluate the prognostic value of circulating tumor cell (CTC) in tumor patients during treatment.

METHODS

This study retrospectively analyzed clinical data obtained from 174 cancer patients during treatment. The relationship between the CTC counts and clinicopathological variables was analyzed. A ROC curve was applied to determine the optimal cut-off values and assess the predictive ability of the prognostic indicators. The overall survival (OS) for different prognostic factors was calculated using the Kaplan-Meier method, and the difference between the survival curves was then compared using the log-rank test. Cox regression model was used to investigate the effect of independent factors on patients' survival.

RESULTS

The CTC-positive rate was positively correlated with the clinicopathological variables of TNM stage, tumor differentiation, serum CEA level, and ki-67%. In the differential analysis of hematological microenvironment parameters in CTC-positive and CTC-negative samples, the complete blood count, blood biological chemistry, tumor markers (CEA, CA19-9, CA72-4), and lymphocyte subpopulation were statistically significant. The results of the ROC curve analysis indicated that the serum CEA level was the best diagnostic indicator to discriminate the CTC count in tumor patients. Additionally, the results of the univariate and multivariate analyses of OS in relation to clinical variables revealed that the CTC counts were an independent prognostic factor for unfavorable OS.

CONCLUSION

The CTC counts in patients with tumors undergoing treatment were significantly correlated with hematological microenvironment parameters. The detection of CTCs may therefore be used as an indicator of tumor prognosis.

A machine learning model for colorectal liver metastasis post-hepatectomy prognostications

Background

Currently, surgical resection is the mainstay for colorectal liver metastases (CRLM) management and the only potentially curative treatment modality. Prognostication tools can support patient selection for surgical resection to maximize therapeutic benefit. This study aimed to develop a survival prediction model using machine learning based on a multicenter patient sample in Hong Kong.

Methods

Patients who underwent hepatectomy for CRLM between 1 January 2009 and 31 December 2018 in four hospitals in Hong Kong were included in the study. Survival analysis was performed using Cox proportional hazards (CPH). A stepwise selection on Cox multivariable models with Least Absolute Shrinkage and Selection Operator (LASSO) regression was applied to a multiply-imputed dataset to build a prediction model. The model was validated in the validation set, and its performance was compared with that of Fong Clinical Risk Score (CRS) using concordance index.

Results

A total of 572 patients were included with a median follow-up of 3.6 years. The full models for overall survival (OS) and recurrence-free survival (RFS) consist of the same 8 established and novel variables, namely colorectal cancer nodal stage, CRLM neoadjuvant treatment, Charlson Comorbidity Score, pre-hepatectomy bilirubin and carcinoembryonic antigen (CEA) levels, CRLM largest tumor diameter, extrahepatic metastasis detected on positron emission-tomography (PET)-scan as well as KRAS status. Our CRLM Machine-learning Algorithm Prognostication model (CMAP) demonstrated better ability to predict OS (C-index =0.651), compared with the Fong CRS for 1-year (C-index =0.571) and 5-year OS (C-index =0.574). It also achieved a C-index of 0.651 for RFS.

Conclusions

We present a promising machine learning algorithm to individualize prognostications for patients following resection of CRLM with good discriminative ability.

Crosstalk between Circulating Tumor Cells and Plasma Proteins-Impact on Coagulation and Anticoagulation

Cancer metastasis is a complex process. After their intravasation into the circulation, the cancer cells are exposed to a harsh environment of physical and biochemical hazards. Whether circulating tumor cells (CTCs) survive and escape from blood flow defines their ability to metastasize. CTCs sense their environment with surface-exposed receptors. The recognition of corresponding ligands, e.g., fibrinogen, by integrins can induce intracellular signaling processes driving CTCs' survival. Other receptors, such as tissue factor (TF), enable CTCs to induce coagulation. Cancer-associated thrombosis (CAT) is adversely connected to patients' outcome. However, cancer cells have also the ability to inhibit coagulation, e.g., through expressing thrombomodulin (TM) or heparan sulfate (HS), an activator of antithrombin (AT). To that extent, individual CTCs can interact with plasma proteins, and whether these interactions are connected to metastasis or clinical symptoms such as CAT is largely unknown. In the present review, we discuss the biological and clinical relevance of cancer-cell-expressed surface molecules and their interaction with plasma proteins. We aim to encourage future research to expand our knowledge of the CTC interactome, as this may not only yield new molecular markers improving liquid-biopsy-based diagnostics but also additional targets for better cancer therapies.

Liquid biopsy approaches and immunotherapy in colorectal cancer for precision medicine: Are we there yet?

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths globally, with nearly half of patients detected in the advanced stages. This is due to the fact that symptoms associated with CRC often do not appear until the cancer has reached an advanced stage. This suggests that CRC is a cancer with a slow progression, making it curable and preventive if detected in its early stage. Therefore, there is an urgent clinical need to improve CRC early detection and personalize therapy for patients with this cancer. Recently, liquid biopsy as a non-invasive or nominally invasive approach has attracted considerable interest for its real-time disease monitoring capability through repeated sample analysis. Several studies in CRC have revealed the potential for liquid biopsy application in a real clinical setting using circulating RNA/miRNA, circulating tumor cells (CTCs), exosomes, etc. However, Liquid biopsy still remains a challenge since there are currently no promising results with high specificity and specificity that might be employed as optimal circulatory biomarkers. Therefore, in this review, we conferred the plausible role of less explored liquid biopsy components like mitochondrial DNA (mtDNA), organoid model of CTCs, and circulating cancer-associated fibroblasts (cCAFs); which may allow researchers to develop improved strategies to unravel unfulfilled clinical requirements in CRC patients. Moreover, we have also discussed immunotherapy approaches to improve the prognosis of MSI (Microsatellite Instability) CRC patients using neoantigens and immune cells in the tumor microenvironment (TME) as a liquid biopsy approach in detail.

Hepatocellular carcinoma risk-stratification based on ASGR1 in circulating epithelial cells for cancer interception

Purpose: Lack of diagnostic and prognostic biomarkers in hepatocellular carcinoma impedes stratifying patients based on their risk of developing cancer. The aim of this study was to evaluate phenotypic and genetic heterogeneity of circulating epithelial cells (CECs) based on asialoglycoprotein receptor 1 (ASGR1) and miR-122-5p expression as potential diagnostic and prognostic tools in patients with hepatocellular carcinoma (HCC) and liver cirrhosis (LC). Methods: Peripheral blood samples were extracted from LC and HCC patients at different disease stages. CECs were isolated using positive immunomagnetic selection. Genetic and phenotypic characterization was validated by double immunocytochemistry for cytokeratin (CK) and ASGR1 or by in situ hybridization with miR-122-5p and CECs were visualized by confocal microscopy. Results: The presence of CECs increased HCC risk by 2.58-fold, however, this was only significant for patients with previous LC (p = 0.028) and not for those without prior LC (p = 0.23). Furthermore, the number of CECs lacking ASGR1 expression correlated significantly with HCC incidence and absence of miR-122-5p expression (p = 0.014; r = 0.23). Finally, overall survival was significantly greater for patients at earlier cancer stages (p = 0.018), but this difference was only maintained in the group with the presence of CECs (p = 0.021) whereas progression-free survival was influenced by the absence of ASGR1 expression. Conclusion: Identification and characterization of CECs by ASGR1 and/or miR-122-5p expression may be used as a risk-stratification tool in LC patients, as it was shown to be an independent prognostic and risk-stratification marker in LC and early disease stage HCC patients.

Dynamic liquid biopsy components as predictive and prognostic biomarkers in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide. The diagnosis, prognosis and therapeutic monitoring of CRC depends largely on tissue biopsy. However, due to tumor heterogeneity and limitations such as invasiveness, high cost and limited applicability in longitudinal monitoring, liquid biopsy has gathered immense attention in CRC. Liquid biopsy has several advantages over tissue biopsy including ease of sampling, effective monitoring, and longitudinal assessment of treatment dynamics. Furthermore, the importance of liquid biopsy is signified by approval of several liquid biopsy assays by regulatory bodies indicating the powerful approach of liquid biopsy for comprehensive CRC screening, diagnostic and prognostics. Several liquid biopsy biomarkers such as novel components of the microbiome, non-coding RNAs, extracellular vesicles and circulating tumor DNA are extensively being researched for their role in CRC management. Majority of these components have shown promising results on their clinical application in CRC including early detection, observe tumor heterogeneity for treatment and response, prediction of metastases and relapse and detection of minimal residual disease. Therefore, in this review, we aim to provide updated information on various novel liquid biopsy markers such as a) oral microbiota related bacterial network b) gut microbiome-associated serum metabolites c) PIWI-interacting RNAs (piRNAs), microRNA(miRNAs), Long non-coding RNAs (lncRNAs), circular RNAs (circRNAs) and d) circulating tumor DNAs (ctDNA) and circulating tumor cells (CTC) for their role in disease diagnosis, prognosis, treatment monitoring and their applicability for personalized management of CRC.

Deep Phenotypic Characterisation of CTCs by Combination of Microfluidic Isolation (IsoFlux) and Imaging Flow Cytometry (ImageStream)

Simple Summary

Cells that escape the primary tumour and have the potential ability to colonise distant organs through metastasis are called circulating tumour cells (CTCs). The study of CTCs in colorectal cancer (CRC) has demonstrated their prognostic utility, although current methodologies only allow the evaluation of CTC numbers and a maximum of two markers. Here, we developed a novel protocol for the isolation and characterisation of CTCs by combining two existing technologies. This new methodology allows the simultaneous evaluation of multiple markers and parameters. In particular, we evaluated the expression of a mutant protein (BRAF^V600E) associated with poor response to therapies against EGFR and the expression of PD-L1, a marker for immunotherapy. Based on these markers, we evaluated the CTCs (positive for cytokeratin) of 16 early CRC patients and demonstrated the suitability of our protocol to classify patients into potential responders and non-responders.

Abstract

The isolation of circulating tumour cells (CTCs) in colorectal cancer (CRC) mostly relies on the expression of epithelial markers such as EpCAM, and phenotypic characterisation is usually performed under fluorescence microscopy with only one or two additional markers. This limits the ability to detect different CTC subpopulations based on multiple markers. The aim of this work was to develop a novel protocol combining two platforms (IsoFlux^TM and ImageStream^®X) to improve CTC evaluation. Cancer cell lines and peripheral blood from healthy donors were used to evaluate the efficiency of each platform independently and in combination. Peripheral blood was extracted from 16 early CRC patients (before loco-regional surgery) to demonstrate the suitability of the protocol for CTC assessment. Additionally, peripheral blood was extracted from nine patients one month after surgery to validate the utility of our protocol for identifying CTC subpopulation changes over time. Results: Our protocol had a mean recovery efficiency of 69.5% and a limit of detection of at least four cells per millilitre. We developed an analysis method to reduce noise from magnetic beads used for CTC isolation. CTCs were isolated from CRC patients with a median of 37 CTCs (IQ 13.0–85.5) at baseline. CTCs from CRC patients were significantly (p < 0.0001) larger than cytokeratin (CK)-negative cells, and patients were stratified into two groups based on BRAF^V600E and PD-L1 expression on CK-positive cells. The changes observed over time included not only the number of CTCs but also their distribution into four different subpopulations defined according to BRAF^V600E and PD-L1 positivity. We developed a novel protocol for semi-automatic CTC isolation and phenotypic characterisation by combining two platforms. Assessment of CTCs from early CRC patients using our protocol allowed the identification of two clusters of patients with changing phenotypes over time.

Circulating tumor cells in colorectal cancer in the era of precision medicine

Colorectal cancer (CRC) is one of the main causes of cancer-related morbidity and mortality across the globe. Although serum biomarkers such as carcinoembryonic antigen (CEA) and carbohydrate antigen 19–9 (CA-199) have been prevalently used as biomarkers in various cancers, they are neither very sensitive nor highly specific. Repeated tissue biopsies at different times of the disease can be uncomfortable for cancer patients. Additionally, the existence of tumor heterogeneity and the results of local biopsy provide limited information about the overall tumor biology. Against this backdrop, it is necessary to look for reliable and noninvasive biomarkers of CRC. Circulating tumor cells (CTCs), which depart from a primary tumor, enter the bloodstream, and imitate metastasis, have a great potential for precision medicine in patients with CRC. Various efficient CTC isolation platforms have been developed to capture and identify CTCs. The count of CTCs, as well as their biological characteristics and genomic heterogeneity, can be used for the early diagnosis, prognosis, and prediction of treatment response in CRC. This study reviewed the existing CTC isolation techniques and their applications in the clinical diagnosis and treatment of CRC. The study also presented their limitations and provided future research directions.

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.

When Tissue is an Issue the Liquid Biopsy is Nonissue: A Review

Precision medicine has impacted the field of medical oncology by introducing personalized therapies, improving all measurable outcomes. This field, in turn, has expanded to obtaining and analyzing a vast and ever-increasing amount of genomic information. One technique currently applied is the liquid biopsy, which consists of detecting and isolating DNA and exosomes in cancer patients. Newly developed techniques have made it possible to use the liquid biopsy in a wide range of settings. However, challenges regarding the validation of its clinical utility exist because of a lack of standardization across different techniques and tumor types, confounder genomic information, lack of appropriate clinical trial designs, and a non-measured, and therefore not estimated, economic impact on population health. Nowadays, liquid biopsy is not routinely used, but ongoing research is increasing its popularity, and a new era in oncology is developing. Therefore, it is essential to have an in-depth understanding of the liquid biopsy technique. In this review, we summarize the leading techniques and liquid biopsy applications in cancer.

Efficacy and safety of short duration radiotherapy combined with chemotherapy for advanced rectal cancer

BACKGROUND

Radiotherapy or chemoradiotherapy is widely used for the treatment of rectal cancer preoperatively. Although the combination of radiotherapy and chemotherapy as an established preoperative neoadjuvant therapy shows high efficacy in the treatment of rectal cancer, some patients experience a response of poor tolerance and outcomes due to the long duration radiotherapy. The study compared short duration radiotherapy plus chemotherapy vs long duration radiotherapy plus chemotherapy for rectal cancer to determine whether short duration radiation treatment should be considered to diminish complications, reduce risk of recurrence and improve survival in patients with rectal cancer.

AIM

To evaluate the efficacy and safety of short duration radiotherapy combined with chemotherapy for the treatment of advanced rectal cancer.

METHODS

One hundred patients with stage IIIB or higher severe rectal cancer were selected as the study subjects at The First Affiliated Hospital of Hebei North University between December 2018 and December 2019. The patients were assigned to different groups based on the treatment regimens. Fifty patients who received preoperative short durations of radiotherapy plus chemotherapy were enrolled in an observation group and fifty patients who received conventional radiotherapy and chemotherapy were enrolled in a control group. Colonoscopic biopsy was performed for all patients with pathological diagnosis of rectal cancer. The expression of tumor-related factors such as RUNX3 and Ki-67 was quantitatively analyzed using immunohistochemistry in the tissues of the patients before and after treatment. Moreover, the duration of procedure, the amount of bleeding during the operation, the anus-conserving rate, the incidence of postoperative complications (wound infection, anastomotic leakage, postoperative intestinal obstruction, etc.) and postoperative pathology were compared between the two groups. The overall survival rate, recurrence rate and distant metastasis rate were also compared through postoperative reexamination and regular follow-up.

RESULTS

There was no significant difference in the positive expression rate of RUNX3 and Ki-67 between the two groups before the treatment (P > 0.05). Compared with the pretreatment value, the positive rate of RUNX3 was increased and the positive rate of Ki-67 was decreased in both groups after the treatment (all P < 0.05). The incidence of leukopenia, thrombocytopenia, neutropenia and diarrhea were higher in the observation group than in the control group (all P < 0.05). There was no significant difference in the incidence of anemia, fatigue, neurotoxicity and nausea and vomiting between the two groups (all P > 0.05). No significant difference was observed in the duration of procedure, intraoperative bleeding, the anus-conserving rate and the incidence of postoperative complications between the two groups (P > 0.05). After 1 year of follow-up, the 1-yr survival rate was 80.0% in the observation group and 68.0% in the control group, the recurrence rate was 8.0% in the observation group and 10.0% in the control group, the distant metastasis rate was 6.0% in the observation group and 8.0% in the control group difference (all P < 0.05).

CONCLUSION

Short duration radiotherapy combined with chemotherapy can improve the cure rate, prolong the survival time and reduce the incidence of complications in patients with advanced rectal cancer.

The Polemic Diagnostic Role of TP53 Mutations in Liquid Biopsies from Breast, Colon and Lung Cancers

Being minimally invasive and thus allowing repeated measures over time, liquid biopsies are taking over traditional solid biopsies in certain circumstances such as those for unreachable tumors, very early stages or treatment monitoring. However, regarding TP53 mutation status analysis, liquid biopsies have not yet substituted tissue samples, mainly due to the lack of concordance between the two types of biopsies. This needs to be examined in a study-dependent manner, taking into account the particular type of liquid biopsy analyzed, that is, circulating tumor cells (CTCs) or cell-free DNA (cfDNA), its involvement in the tumor biology and evolution and, finally, the technology used to analyze each biopsy type. Here, we review the main studies analyzing TP53 mutations in either CTCs or cfDNA in the three more prevalent solid tumors: breast, colon and lung cancers. We evaluate the correlation for mutation status between liquid biopsies and tumor tissue, suggesting possible sources of discrepancies, as well as evaluating the clinical utility of using liquid biopsies for the analysis of TP53 mutation status and the future actions that need to be undertaken to make liquid biopsy analysis a reality for the evaluation of TP53 mutations.

Precision Prevention and Cancer Interception: The New Challenges of Liquid Biopsy

Despite major therapeutic progress, most advanced solid tumors are still incurable. Cancer interception is the active way to combat cancer onset, and development of this approach within high-risk populations seems a logical first step. Until now, strategies for the identification of high-risk subjects have been based on low-sensitivity and low-specificity assays. However, new liquid biopsy assays, "the Rosetta Stone of the new biomedicine era," with the ability to identify circulating biomarkers with unprecedented sensitivity, promise to revolutionize cancer management. This review focuses on novel liquid biopsy approaches and the applications to cancer interception. Cancer interception involves the identification of biomarkers associated with developing cancer, and includes genetic and epigenetic alterations, as well as circulating tumor cells and circulating epithelial cells in individuals at risk, and the implementation of therapeutic strategies to prevent the beginning of cancer and to stop its development. Large prospective studies are needed to confirm the potential role of liquid biopsy for early detection of precancer lesions and tumors.

Challenges and opportunities of cfDNA analysis implementation in clinical practice: Perspective of the International Society of Liquid Biopsy (ISLB)

Precision medicine was born with the development of new diagnostic techniques and targeted drugs, yielding better outcomes in cancer care. With the evolution and increasing sensitivity for detecting oncogenic drivers, liquid biopsies (LBs), specifically cell-free DNA (cfDNA) analysis, have been proposed as a minimally-invasive technique for genomic profiling. Ranging from sequencing techniques to PCR-based methods and other more complex strategies, this approach, currently applicable in some solid tumors with robust evidence, is showing promising opportunities in other cancers. However, difficulties in validating their clinical utility exist within limitation at different levels among several techniques, reporting of the results, lack of appropriate clinical trial designs, and unknown economic impact. One of the aims of the ISLB is to create recommendations to develop reliable and sustainable diagnostic, prognostic and predictive tools using LBs. This paper is addressing these objectives, helping the healthcare providers and scientific community to understand the potential of LB.

Extracellular vesicle-miRNAs as liquid biopsy biomarkers for disease identification and prognosis in metastatic colorectal cancer patients

Disseminated disease is present in ≈50% of colorectal cancer patients upon diagnosis, being responsible for most of cancer deaths. Addition of biological drugs, as Bevacizumab, to chemotherapy, has increased progression free survival and overall survival of metastatic colorectal cancer (mCRC) patients. However, these benefits have been only reported in a small proportion of patients. To date, there are not biomarkers that could explain the heterogeneity of this disease and would help in treatment selection. Recent findings demonstrated that microRNAs (miRNAs) play an important role in cancer and they can be encapsulated with high stability into extracellular vesicles (EVs) that are released in biological fluids. EVs can act as cell-to-cell communicators, transferring genetic information, such as miRNAs. In this context, we aimed to investigate serum EV associated miRNAs (EV-miRNAs) as novel non-invasive biomarkers for the diagnosis and prognosis of Bevacizumab-treated mCRC patients. We observed that baseline miRNA-21 and 92a outperformed carcinoembryonic antigen levels in the diagnosis of our 44 mCRC patients, compared to 17 healthy volunteers. In addition, patients who died presented higher levels of miRNA-92a and 222 at 24 weeks. However, in the multivariate Cox analysis, higher levels of miRNA-222 at 24 weeks were associated with lower overall survival. Altogether, these data indicate that EV-miRNAs have a strong potential as liquid biopsy biomarkers for the identification and prognosis of mCRC.

Circulating Tumor Cells in Gastrointestinal Cancers: Current Status and Future Perspectives

Circulating tumor cells (CTCs), which are now defined as the "break away" cancer cells that derive from primary- or metastatic-tumor sites and present in the bloodstream, are considered to be the precursors of metastases. Considering the key role of CTCs in cancer progression, researchers are committed to analyze them in the past decades and many technologies have been proposed for achieving CTCs isolation and characterization with highly sensitivity and specificity until now. On this basis, clinicians gradually realize the clinical values of CTCs' detection through various clinical studies. As a "liquid biopsy," CTCs' detection and measurement can supply important information for predicting patient's survival, monitoring of response/resistance, assessment of minimal residual disease, evaluating distant metastasis, and sometimes, customizing therapy choices. Nowadays, eliminating CTCs of the blood circulation has been regarded as a promising method to prevent tumor metastasis. However, research on CTCs still faces many challenges. Herein, we present an overview to discuss the current concept of CTCs, summarize the available techniques for CTCs detection, and provide an update on the clinical significance of CTCs in gastrointestinal malignancies, especially focus on gastric and colorectal cancer.

Cooperative and Escaping Mechanisms between Circulating Tumor Cells and Blood Constituents

Metastasis is the leading cause of cancer-related deaths and despite measurable progress in the field, underlying mechanisms are still not fully understood. Circulating tumor cells (CTCs) disseminate within the bloodstream, where most of them die due to the attack of the immune system. On the other hand, recent evidence shows active interactions between CTCs and platelets, myeloid cells, macrophages, neutrophils, and other hematopoietic cells that secrete immunosuppressive cytokines, which aid CTCs to evade the immune system and enable metastasis. Platelets, for instance, regulate inflammation, recruit neutrophils, and cause fibrin clots, which may protect CTCs from the attack of Natural Killer cells or macrophages and facilitate extravasation. Recently, a correlation between the commensal microbiota and the inflammatory/immune tone of the organism has been stablished. Thus, the microbiota may affect the development of cancer-promoting conditions. Furthermore, CTCs may suffer phenotypic changes, as those caused by the epithelial–mesenchymal transition, that also contribute to the immune escape and resistance to immunotherapy. In this review, we discuss the findings regarding the collaborative biological events among CTCs, immune cells, and microbiome associated to immune escape and metastatic progression.