Analysis of Circulating Tumor Cells in Ovarian Cancer and Their Clinical Value as a Biomarker

Unveiling the impact of circulating tumor cells: Two decades of discovery and clinical advancements in solid tumors

Circulating tumor cells (CTCs) enumeration and molecular profiling hold promise in revolutionizing the management of solid tumors. Their understanding has evolved significantly over the past two decades, encompassing pivotal biological discoveries and clinical studies across various malignancies. While for some tumor types, such as breast, prostate, and colorectal cancer, CTCs are ready to enter clinical practice, for others, additional research is required. CTCs serve as versatile biomarkers, offering insights into tumor biology, metastatic progression, and treatment response. This review summarizes the latest advancements in CTC research and highlights future directions of investigation. Special attention is given to concurrent evaluations of CTCs and other circulating biomarkers, particularly circulating tumor DNA. Multi-analyte assessment holds the potential to unlock the full clinical capabilities of liquid biopsy. In conclusion, CTCs represent a transformative biomarker in precision oncology, offering extraordinary opportunities to translate scientific discoveries into tangible improvements in patient care.

Gene expression markers in peripheral blood and outcome in patients with platinum-resistant ovarian cancer: A study of the European GANNET53 consortium

Disease progression is a major problem in ovarian cancer. There are very few treatment options for patients with platinum-resistant ovarian cancer (PROC), and therefore, these patients have a particularly poor prognosis. The aim of the present study was to identify markers for monitoring the response of 123 PROC patients enrolled in the Phase I/II GANNET53 clinical trial, which evaluated the efficacy of Ganetespib in combination with standard chemotherapy versus standard chemotherapy alone. In total, 474 blood samples were collected, comprising baseline samples taken before the first administration of the study drugs and serial samples taken during treatment until further disease progression (PD). After microfluidic enrichment, 27 gene transcripts were analyzed using quantitative polymerase chain reaction and their utility for disease monitoring was evaluated. At baseline, ERCC1 was associated with an increased risk of PD (hazard ratio [HR] 1.75, 95% confidence interval [CI]: 1.20-2.55; p = 0.005), while baseline CDH1 and ESR1 may have a risk-reducing effect (CDH1 HR 0.66, 95% CI: 0.46-0.96; p = 0.024; ESR1 HR 0.58, 95% CI: 0.39-0.86; p = 0.002). ERCC1 was observed significantly more often (72.7% vs. 53.9%; p = 0.032) and ESR1 significantly less frequently (59.1% vs. 78.3%; p = 0.018) in blood samples taken at radiologically confirmed PD than at controlled disease. At any time during treatment, ERCC1-presence and ESR1-absence were associated with short PFS and with higher odds of PD within 6 months (odds ratio 12.77, 95% CI: 4.08-39.97; p < 0.001). Our study demonstrates the clinical relevance of ESR1 and ERCC1 and may encourage the analysis of liquid biopsy samples for the management of PROC patients.

The role of liquid biopsy in epithelial ovarian cancer: State of the art

The clinical implementation of liquid biopsy has dramatically modified the analytical paradigm for several solid tumors. To date, however, only circulating free DNA (cfDNA) has been approved in clinical practice to select targeted treatments for patients with colorectal cancer (CRC), non-small cell lung cancer (NSCLC), and breast cancer (BC). Interestingly, emerging liquid biopsy analytes in peripheral blood, including circulating tumor cells (CTC), miRNA, and extracellular vesicles (EVs), have been shown to play a crucial role in the clinical management of solid tumor patients. Here, we review how these blood-based biomarkers may positively impact early diagnosis, prognosis, and treatment response in ovarian cancer (OC) patients.

High-Grade Serous Ovarian Cancer-A Risk Factor Puzzle and Screening Fugitive

High-grade serous ovarian cancer (HGSOC) is the most lethal tumor of the female genital tract. Despite extensive studies and the identification of some precursor lesions like serous tubal intraepithelial cancer (STIC) or the deviated mutational status of the patients (BRCA germinal mutation), the pathophysiology of HGSOC and the existence of particular risk factors is still a puzzle. Moreover, a lack of screening programs results in delayed diagnosis, which is accompanied by a secondary chemo-resistance of the tumor and usually results in a high recurrence rate after the primary therapy. Therefore, there is an urgent need to identify the substantial risk factors for both predisposed and low-risk populations of women, as well as to create an economically and clinically justified screening program. This paper reviews the classic and novel risk factors for HGSOC and methods of diagnosis and prediction, including serum biomarkers, the liquid biopsy of circulating tumor cells or circulating tumor DNA, epigenetic markers, exosomes, and genomic and proteomic biomarkers. The novel future complex approach to ovarian cancer diagnosis should be devised based on these findings, and the general outcome of such an approach is proposed and discussed in the paper.

Comprehensive analysis reveals dual biological function roles of EpCAM in kidney renal clear cell carcinoma

Background

Epithelial cell adhesion molecule (EpCAM), a well-established marker for circulating tumor cells, plays a crucial role in the complex process of cancer metastasis. The primary objective of this investigation is to study EpCAM expression in pan-cancer and elucidate its significance in the context of kidney renal clear cell carcinoma (KIRC).

Methods

Data obtained from the public database was harnessed for the comprehensive assessment of the EpCAM expression levels and prognostic and clinicopathological correlations in thirty-three types of cancer. EpCAM was validated in our own KIRC sequencing and immunohistochemical cohorts. Subsequently, an in-depth exploration was conducted to scrutinize the interrelationship between EpCAM and various facets, including immune cells, immune checkpoints, and chemotherapy drugs. We employed Cox regression analysis to identify prognostic immunomodulators associated with EpCAM, which were subsequently utilized in the development of a prognostic model. The model was validated in our own clinical cohort and public datasets, and compared with 137 published models. The role of EpCAM in KIRC was explored by biological function experiments in vitro.

Results

While EpCAM exhibited pronounced overexpression across a wide spectrum of cancer types, a notable reduction was observed in KIRC tissues. As grade increased, EpCAM expression decreased. EpCAM expression decreased in patients without metastasis. EpCAM mRNA and protein levels were used as independent, favorable prognostic factors in patients with KIRC in our own cohort. The expression of EpCAM exhibited strong associations with immune-related pathways, demonstrating an inverse correlation with the majority of immune cell types. Immune checkpoint inhibitors exert better therapeutic effects on patients with low EpCAM expression. In addition, EpCAM can be used as a drug resistance indicator and guide the clinical medication of patients with KIRC. A robust model, which had good predictive accuracy and applicability, showed significant superiority over other models. Importantly, EpCAM played the dual roles of promoting proliferation and resisting metastasis in KIRC.

Conclusion

In the context of KIRC, EpCAM assumes a surprising dual role, where it not only facilitates cell proliferation but also exerts resistance against the metastatic process. EpCAM serves as a standalone prognostic marker for patients with KIRC, and related models can also effectively predict prognosis. These discoveries offer novel perspectives on the functional significance of EpCAM in the context of KIRC.

Liquid biopsy in ovarian cancer in China and the world: current status and future perspectives

Ovarian cancer (OC) is the eighth most common cancer in women, but the mild, non-specific clinical presentation in early stages often prevents diagnosis until progression to advanced-stage disease, contributing to the high mortality associated with OC. While serum cancer antigen 125 (CA-125) has been successfully used as a blood-borne marker and is routinely monitored in patients with OC, CA-125 testing has limitations in sensitivity and specificity and does not provide direct information on important molecular characteristics that can guide treatment decisions, such as homologous recombination repair deficiency. We comprehensively review the literature surrounding methods based on liquid biopsies, which may provide improvements in sensitivity, specificity, and provide valuable additional information to enable early diagnosis, monitoring of recurrence/progression/therapeutic response, and accurate prognostication for patients with OC, highlighting applications of this research in China.

Development of adaptive anoikis resistance promotes metastasis that can be overcome by CDK8/19 Mediator kinase inhibition

Anoikis resistance or evasion of cell death triggered by cell detachment into suspension is a hallmark of cancer that is concurrent with cell survival and metastasis. The effects of frequent matrix detachment encounters on the development of anoikis resistance in cancer remains poorly defined. Here we show using a panel of ovarian cancer models, that repeated exposure to suspension stress in vitro followed by attached recovery growth leads to the development of anoikis resistance paralleling in vivo development of anoikis resistance in ovarian cancer ascites. This resistance is concurrent with enhanced invasion, chemoresistance and the ability of anoikis adapted cells to metastasize to distant sites. Adapted anoikis resistant cells show a heightened dependency on oxidative phosphorylation and can also evade immune surveillance. We find that such acquired anoikis resistance is not genetic, as acquired resistance persists for a finite duration in the absence of suspension stress. Transcriptional reprogramming is however essential to this process, as acquisition of adaptive anoikis resistance in vitro and in vivo is exquisitely sensitive to inhibition of CDK8/19 Mediator kinase, a pleiotropic regulator of transcriptional reprogramming. Our data demonstrate that growth after recovery from repeated exposure to suspension stress is a direct contributor to metastasis and that inhibition of CDK8/19 Mediator kinase during such adaptation provides a therapeutic opportunity to prevent both local and distant metastasis in cancer.

Purification of Circulating Tumor Cells Based on Multiantibody-Modified Magnetic Nanoparticles and Molecular Analysis toward Epithelial Ovarian Cancer Detection

Circulating tumor cells (CTCs) are valuable circulating biomarkers of cancer, which carry primary tumor information and may provide real-time assessment of tumor status as well as treatment response in cancer patients. Herein, we developed a novel assay for accurate diagnosis and dynamic monitoring of epithelial ovarian cancer (EOC) using CTC RNA analysis. Multiantibody-modified magnetic nanoparticles were prepared for purification of EOC CTCs from whole blood samples of clinical patients. Subsequently, nine EOC-specific mRNAs of purified CTCs were quantified using droplet digital PCR. The EOC CTC Score was generated using a multivariate logistic regression model for each sample based on the transcripts of the nine genes. This assay exhibited a distinguishing diagnostic performance for the detection of EOC (n = 17) from benign ovarian tumors (n = 30), with an area under the receiver operating characteristic curve (AUC) of 0.96 (95% CI = 0.91-1.00). Moreover, dynamic changes of the EOC CTC Score were observed in patients undergoing treatment, demonstrating the potential of the assay for monitoring EOC. In conclusion, we present an accurate assay for the diagnosis and monitoring of EOC via CTC RNA analysis, and the results suggest that it may provide a promising solution for the detection and treatment response assessment of EOC.

Identification of RAD51 foci in cancer-associated circulating cells of patients with high-grade serous ovarian cancer: association with treatment outcomes

OBJECTIVE

Fifty percent of patients with high-grade serous ovarian cancer harbor defects in the homologous recombination repair pathway. RAD51 foci form where DNA is damaged, indicating its involvement in repairing double-stranded breaks. High levels of RAD51 in ovarian cancer tissue have been associated with a poorer prognosis.

OBJECTIVE

To demonstrate RAD51 foci in circulating cancer-associated cells of patients with ovarian cancer and their association with clinical outcomes.

METHODS

One hundred and twenty-four patients with high-grade serous ovarian cancer had blood samples taken at strategic points during treatment and follow-up. Cells were stained using WT1 and RAD51 antibodies with immunofluorescence and reviewed under Leica camera microscopy; RAD51 foci were counted. Correlations were made between numbers of RAD51 foci and treatment response, BRCA status, and progression-free survival.

RESULTS

RAD51 foci were identified in all patients (n=42) with wild-type BRCA. BRCA mutant/homologous recombination deficiency-positive patients (n=8) had significantly lower numbers of RAD51 foci (p=0.009). Responders to treatment (n=32) had a reduction in circulating cells (p=0.02) and RAD51 foci (p=0.0007). Numbers of RAD51 foci were significantly higher in the platinum-resistant population throughout treatment: at the start of treatment, in 56 platinum-sensitive patients there was a mean of 3.6 RAD51 foci versus 6.2 in 15 platinum-resistant patients (p=0.02). Patients with a high number of RAD51 foci had worse median progression-free survival: in 39 patients with a mean of <3 RAD51 foci at treatment start, median progression-free survival had not been reached, compared with 32 patients with >3 RAD51 foci whose progression-free survival was 13 months (p=0.04).

CONCLUSIONS

Levels of RAD51 foci in circulating cancer-associated cells of patients with high-grade serous ovarian cancer are associated with clinical outcomes and may be a more pragmatic method of determining a homologous repair-deficient population.

Liquid biopsy in ovarian cancer: advantages and limitations for prognosis and diagnosis

Ovarian cancer (OC) is a highly fatal gynecologic malignancy, often diagnosed at an advanced stage which presents significant challenges for disease management. The clinical application of conventional tissue biopsy methods and serological biomarkers has limitations for the diagnosis and prognosis of OC patients. Liquid biopsy is a novel sampling method that involves analyzing distinctive tumor elements secreted into the peripheral blood. Growing evidence suggests that liquid biopsy methods such as circulating tumor cells, cell-free RNA, circulating tumor DNA, exosomes, and tumor-educated platelets may improve early prognosis and diagnosis of OC, leading to enhanced therapeutic management of the disease. This study reviewed the evidence demonstrating the utility of liquid biopsy components in OC prognosis and diagnosis, and evaluated the current advantages and limitations of these methods. Additionally, the existing obstacles and crucial topics for future studies utilizing liquid biopsy in OC patients were discussed.

Characteristics of Extracellular Vesicles from a High-Grade Serous Ovarian Cancer Cell Line Derived from a Platinum-Resistant Patient as a Potential Tool for Aiding the Prediction of Responses to Chemotherapy

Platinum-resistant high-grade serous ovarian cancer (HGSOC) is invariably a fatal disease. A central goal of ovarian cancer research is therefore to develop new strategies to overcome platinum resistance. Treatment is thus moving towards personalized therapy. However, validated molecular biomarkers that predict patients' risk of developing platinum resistance are still lacking. Extracellular vesicles (EVs) are promising candidate biomarkers. EpCAM-specific EVs are largely unexplored biomarkers for predicting chemoresistance. Using transmission electron microscopy, nanoparticle tracking analysis and flow cytometry, we compared the characteristics of EVs released from a cell line derived from a clinically confirmed cisplatin-resistant patient (OAW28) and EVs released from two cell lines from tumors sensitive to platinum-based chemotherapy (PEO1 and OAW42). We demonstrated that EVs released from the HGSOC cell line of chemoresistant patients exhibited greater size heterogeneity, a larger proportion of medium/large (>200 nm) Evs and a higher number of released EpCAM-positive EVs of different sizes, although the expression of EpCAM was predominant in EVs larger than 400 nm. We also found a strong positive correlation between the concentration of EpCAM-positive EVs and the expression of cellular EpCAM. These results may contribute to the prediction of platinum resistance in the future, although they should first be validated in clinical samples.

Diagnostic and prognostic value of circulating tumor cells in Indian women with suspected ovarian cancer

Background

"Liquid biopsy," where body fluids are screened for biomarkers, is gathering substantial research. We aimed to examine women with suspected ovarian cancer for the presence of circulating tumor cells (CTCs) and study its role in prediction of chemoresistance and survival.

Methods

Magnetic powder labeled monoclonal antibodies for epithelial cell adhesion molecule (EpCAM), mucin 1 cell surface associated, mucin 16 cell surface associated, or carbohydrate antigen 125 (CA125), were prepared according to the manufacturer's protocol. Expression of three ovarian cancer related genes was detected in CTCs using multiplex reverse transcriptase-polymerase chain reaction. CTCs and serum CA125 were measured in 100 patients with suspected ovarian cancer. Correlations with clinicopathological parameters and treatment were analyzed.

Results

CTCs were detected in 18/70 (25.7%) of women with malignancy compared to 0/30 (0.0%) in those with benign gynecologic diseases (P = 0.001). The sensitivity and specificity of the CTC test for predicting a malignant histology in pelvic masses were 27.7% (95% CI: 16.3%, 37.7%) and 100% (95% CI: 85.8%, 100%), respectively. The number of CTCs correlated with stage of ovarian cancer (P = 0.030). The presence of EpCAM + CTC at primary diagnosis in ovarian cancer was found to be an independent predictor of a poor progression free survival (HR, 3.3; 95% CI, 1.3-8.4; P = 0.010), overall survival (HR, 2.6; 95% CI,1.1-5.6; P = 0.019), and resistance to chemotherapy (OR 8.6; 95% CI, 1.8-43.7; P = 0.009).

Conclusion

Expression of EpCAM + CTC in ovarian cancer predicts platinum resistance and poor prognosis. This information could be further used in investigating anti-EpCAM-targeted therapies in ovarian cancer.

The Role of Circulating Tumor Cells in Ovarian Cancer Dissemination

Metastatic ovarian cancer is the main reason for treatment failures and consequent deaths. Ovarian cancer is predisposed to intraperitoneal dissemination. In comparison to the transcoelomic route, distant metastasis via lymph vessels and blood is less common. The mechanisms related to these two modes of cancer spread are poorly understood. Nevertheless, the presence of tumor cells circulating in the blood of OC patients is a well-established phenomenon confirming the significant role of lymphatic and hematogenous metastasis. Thus, the detection of CTCs may provide a minimally invasive tool for the identification of ovarian cancer, monitoring disease progression, and treatment effectiveness. This review focuses on the biology of ovarian CTCs and the role they may play in cancer diagnosis and therapy.

The application of circulating tumor cell and cell-free DNA liquid biopsies in ovarian cancer

Ovarian cancer is the deadliest gynecological cancer. 70% of the cases are diagnosed at late stages with already developed metastases due to the absence of easily noticeable symptoms. Early-stage ovarian cancer has a good prognosis with a 5-year survival rate reaching 95%, hence the identification of effective biomarkers for early diagnosis is important. Advances in liquid biopsy-based methods can have a significant impact not just on the development of an efficient screening strategy, but also in clinical decision-making with additional molecular profiling and genetic alterations linked to therapy resistance. Despite the well-known advantages of liquid biopsy, there are still challenges that need to be addressed before its routine use in clinical practice. Various liquid biopsy-based biomarkers have been investigated in ovarian cancer; however, in this review, we are concentrating on the current use of cell-free DNA (cfDNA) and circulating tumor cells (CTCs) in disease management, focusing on their emerging importance in clinical practice. We also discuss the technical aspects of these workflows. The analysis of cfDNA is often chosen for the detection of mutations, copy number aberrations, and DNA methylation changes, whereas CTC analysis provides a unique opportunity to study whole cells, thus allowing DNA, RNA, and protein-based molecular profiling as well as in vivo studies. Combined solutions which merge the strengths of cfDNA and CTC approaches should be developed to maximize the potential of liquid biopsy technology.

The Potential Role of MUC16 (CA125) Biomarker in Lung Cancer: A Magic Biomarker but with Adversity

Lung cancer is the second most commonly diagnosed cancer in the world. In terms of the diagnosis of lung cancer, combination carcinoembryonic antigen (CEA) and cancer antigen 125 (CA125) detection had higher sensitivity, specificity, and diagnostic odds ratios than CEA detection alone. Most individuals with elevated serum CA125 levels had lung cancer that was either in stage 3 or stage 4. Serum CA125 levels were similarly elevated in lung cancer patients who also had pleural effusions or ascites. Furthermore, there is strong evidence that human lung cancer produces CA125 in vitro, which suggests that other clinical illnesses outside of ovarian cancer could also be responsible for the rise of CA125. MUC16 (CA125) is a natural killer cell inhibitor. As a screening test for lung and ovarian cancer diagnosis and prognosis in the early stages, CA125 has been widely used as a marker in three different clinical settings. MUC16 mRNA levels in lung cancer are increased regardless of gender. As well, increased expression of mutated MUC16 enhances lung cancer cells proliferation and growth. Additionally, the CA125 serum level is thought to be a key indicator for lung cancer metastasis to the liver. Further, CA125 could be a useful biomarker in other cancer types diagnoses like ovarian, breast, and pancreatic cancers. One of the important limitations of CA125 as a first step in such a screening technique is that up to 20% of ovarian tumors lack antigen expression. Each of the 10 possible serum markers was expressed in 29-100% of ovarian tumors with minimal or no CA125 expression. Therefore, there is a controversy regarding CA125 in the diagnosis and prognosis of lung cancer and other cancer types. In this state, preclinical and clinical studies are warranted to elucidate the clinical benefit of CA125 in the diagnosis and prognosis of lung cancer.

Agent-based modeling predicts RAC1 is critical for ovarian cancer metastasis

Experimental and computational studies pinpoint rate-limiting step(s) in metastasis governed by Rac1. Using ovarian cancer cell and animal models, Rac1 expression was manipulated, and quantitative measurements of cell-cell and cell-substrate adhesion, cell invasion, mesothelial clearance, and peritoneal tumor growth discriminated the tumor behaviors most highly influenced by Rac1. The experimental data were used to parameterize an agent-based computational model simulating peritoneal niche colonization, intravasation, and hematogenous metastasis to distant organs. Increased ovarian cancer cell survival afforded by the more rapid adhesion and intravasation upon Rac1 overexpression is predicted to increase the numbers of and the rates at which tumor cells are disseminated to distant sites. Surprisingly, crowding of cancer cells along the blood vessel was found to decrease the numbers of cells reaching a distant niche irrespective of Rac1 overexpression or knockdown, suggesting that sites for tumor cell intravasation are rate limiting and become accessible if cells intravasate rapidly or are displaced due to diminished viability. Modeling predictions were confirmed through animal studies of Rac1-dependent metastasis to the lung. Collectively, the experimental and modeling approaches identify cell adhesion, rapid intravasation, and survival in the blood as parameters in the ovarian metastatic cascade that are most critically dependent on Rac1.

Molecular Management of High-Grade Serous Ovarian Carcinoma

High-grade serous ovarian carcinoma (HGSOC) represents the most common form of epithelial ovarian carcinoma. The absence of specific symptoms leads to late-stage diagnosis, making HGSOC one of the gynecological cancers with the worst prognosis. The cellular origin of HGSOC and the role of reproductive hormones, genetic traits (such as alterations in P53 and DNA-repair mechanisms), chromosomal instability, or dysregulation of crucial signaling pathways have been considered when evaluating prognosis and response to therapy in HGSOC patients. However, the detection of HGSOC is still based on traditional methods such as carbohydrate antigen 125 (CA125) detection and ultrasound, and the combined use of these methods has yet to support significant reductions in overall mortality rates. The current paradigm for HGSOC management has moved towards early diagnosis via the non-invasive detection of molecular markers through liquid biopsies. This review presents an integrated view of the relevant cellular and molecular aspects involved in the etiopathogenesis of HGSOC and brings together studies that consider new horizons for the possible early detection of this gynecological cancer.

Optimized Transcriptional Signature for Evaluation of MEK/ERK Pathway Baseline Activity and Long-Term Modulations in Ovarian Cancer

Ovarian cancer is the most aggressive and lethal of all gynecologic malignancies. The high activity of the MEK/ERK signaling pathway is tightly associated with tumor growth, high recurrence rate, and treatment resistance. Several transcriptional signatures were proposed recently for evaluation of MEK/ERK activity in tumor tissue. In the present study, we validated the performance of a robust multi-cancer MPAS 10-gene signature in various experimental models and publicly available sets of ovarian cancer samples. Expression of four MPAS genes (PHLDA1, DUSP4, EPHA2, and SPRY4) displayed reproducible responses to MEK/ERK activity modulations across several experimental models in vitro and in vivo. Levels of PHLDA1, DUSP4, and EPHA2 expression were also significantly associated with baseline levels of MEK/ERK pathway activity in multiple human ovarian cancer cell lines and ovarian cancer patient samples available from the TCGA database. Initial platinum therapy resistance and advanced age at diagnosis were independently associated with poor overall patient survival. Taken together, our results demonstrate that the performance of transcriptional signatures is significantly affected by tissue specificity and aspects of particular experimental models. We therefore propose that gene expression signatures derived from comprehensive multi-cancer studies should be always validated for each cancer type.

Blood-based DNA methylation profiling for the detection of ovarian cancer

OBJECTIVES

Ovarian cancer is a fatal gynecological cancer due to the lack of effective screening strategies at early stage. This study explored the utility of DNA methylation profiling of blood samples for the detection of ovarian cancer.

METHODS

Targeted bisulfite sequencing was performed on tissue (n = 152) and blood samples (n = 373) obtained from healthy women, women with benign ovarian tumors, or malignant epithelial ovarian tumors. Based on the tissue-derived differentially-methylated regions, a supervised machine learning algorithm was implemented and cross-validated using the blood-derived DNA methylation profiles of the training cohort (n = 178) to predict and classify each blood sample as malignant or non-malignant. The model was further evaluated using an independent test cohort (n = 184).

RESULTS

Comparison of the DNA methylation profiles of normal/benign and malignant tumor samples identified 1272 differentially-methylated regions, with 49.4% hypermethylated regions and 50.6% hypomethylated regions. Five-fold cross-validation of the model using the training dataset yielded an area under the curve of 0.94. Using the test dataset, the model accurately predicted non-malignancy in 96.2% of healthy women (n = 53) and 93.5% of women with benign tumors (n = 46). For patients with malignant tumors, the model accurately predicted malignancy in 44.4% of stage I-II (n = 9), 86.4% of stage III (n = 59), 100.0% of stage IV tumors (n = 6), and 81.8% of tumors with unknown stage (n = 11). Overall, the model yielded a predictive accuracy of 89.5%.

CONCLUSIONS

Our study demonstrates the potential clinical application of blood-based DNA methylation profiling for the detection of ovarian cancer.

Extracellular vesicle contents as non-invasive biomarkers in ovarian malignancies

Ovarian cancer most commonly presents at an advanced stage where survival is approximately 30% compared with >80% if diagnosed and treated before disease spreads. Diagnostic capabilities have progressed from surgical staging via laparotomy to image-guided biopsies and immunohistochemistry staining, along with advances in technology and medicine. Despite improvements in diagnostic capabilities, population-level screening for ovarian cancer is not recommended. Extracellular vesicles (EVs) are 40–150 nm structures formed when the cellular lipid bilayer invaginates. These structures function in cell signaling, immune responses, cancer progression, and establishing the tumor microenvironment. EVs are found in nearly every bodily fluid, including serum, plasma, ascites, urine, and effusion fluid, and contain molecular cargo from their cell of origin. This cargo can be analyzed to yield information about a possible malignancy. In this review we describe how the cargo of EVs has been studied as biomarkers in ovarian cancer. We bring together studies analyzing evidence for various cargos as ovarian cancer biomarkers. Then, we describe the role of EVs in modulation of the tumor microenvironment. This review also summarizes the therapeutic and translational potential of EVs for their optimal utilization as non-invasive biomarkers for novel treatments against cancer.

High throughput, label-free isolation of circulating tumor cell clusters in meshed microwells

Extremely rare circulating tumor cell (CTC) clusters are both increasingly appreciated as highly metastatic precursors and virtually unexplored. Technologies are primarily designed to detect single CTCs and often fail to account for the fragility of clusters or to leverage cluster-specific markers for higher sensitivity. Meanwhile, the few technologies targeting CTC clusters lack scalability. Here, we introduce the Cluster-Wells, which combines the speed and practicality of membrane filtration with the sensitive and deterministic screening afforded by microfluidic chips. The >100,000 microwells in the Cluster-Wells physically arrest CTC clusters in unprocessed whole blood, gently isolating virtually all clusters at a throughput of >25 mL/h, and allow viable clusters to be retrieved from the device. Using the Cluster-Wells, we isolated CTC clusters ranging from 2 to 100+ cells from prostate and ovarian cancer patients and analyzed a subset using RNA sequencing. Routine isolation of CTC clusters will democratize research on their utility in managing cancer.

Metastatic CTC clusters remain relatively unexplored due to the lack of optimized and practical technologies for their detection. Here the authors report Cluster-Wells to isolate CTC clusters in whole blood; they show this allows viable cluster retrieval for further molecular and functional analysis.

Potential clinical utility of liquid biopsies in ovarian cancer

BACKGROUND

Ovarian cancer (OC) is the most lethal gynecologic malignancy worldwide. One of the main challenges in the management of OC is the late clinical presentation of disease that results in poor survival. Conventional tissue biopsy methods and serological biomarkers such as CA-125 have limited clinical applications. Liquid biopsy is a novel sampling method that analyzes distinctive tumour components released into the peripheral circulation, including circulating tumour DNA (ctDNA), circulating tumour cells (CTCs), cell-free RNA (cfRNA), tumour-educated platelets (TEPs) and exosomes. Increasing evidence suggests that liquid biopsy could enhance the clinical management of OC by improving early diagnosis, predicting prognosis, detecting recurrence, and monitoring response to treatment. Capturing the unique tumour genetic landscape can also guide treatment decisions and the selection of appropriate targeted therapies. Key advantages of liquid biopsy include its non-invasive nature and feasibility, which allow for serial sampling and longitudinal monitoring of dynamic tumour changes over time. In this review, we outline the evidence for the clinical utility of each liquid biopsy component and review the advantages and current limitations of applying liquid biopsy in managing ovarian cancer. We also highlight future directions considering the current challenges and explore areas where more studies are warranted to elucidate its emerging clinical potential.

Circulating Tumor Cell Detection during Neoadjuvant Chemotherapy to Predict Early Response in Locally Advanced Oropharyngeal Cancers: A Prospective Pilot Study

Patients with locally advanced oropharyngeal carcinoma treated with neoadjuvant chemotherapy are reassessed both radiologically and clinically to adapt their treatment after the first cycle. However, some responders show early tumor progression after adjuvant radiotherapy. This cohort study evaluated circulating tumor cells (CTCs) from a population of locally advanced oropharyngeal carcinoma patients treated with docetaxel, cisplatin, and 5-fluorouracil (DCF) induction chemotherapy or DCF with a modified dose and fractioned administration. The counts and phenotypes of CTCs were assessed at baseline and at day 21 of treatment, after isolation using the RosetteSep^TM technique based on negative enrichment. At baseline, 6 out of 21 patients had CTCs (28.6%). On day 21, 5 out of 11 patients had CTCs (41.6%). There was no significant difference in the overall and progression-free survival between patients with or without CTCs at baseline (p = 0.44 and 0.78) or day 21 (p = 0.88 and 0.5). Out of the 11 patients tested at day 21, 4 had a positive variation of CTCs (33%). Patients with a positive variation of CTCs display a lower overall survival. Our findings suggest that the variation in the number of CTCs would be a better guide to the management of treatment, with possible early changes in treatment strategy.

Circulating tumor cells as a "real-time liquid biopsy": Recent advances and the application in ovarian cancer

Even with the latest advances in technology, the treatment of ovarian cancer remains a big challenge because it is typically diagnosed at advanced stage, is prone to early relapse in spite of aggressive treatment and has an extremely poor prognosis. Circulating tumor cells (CTCs) can be used as a non-invasive "real-time liquid biopsy", which has shown the value of diagnosis, assessment of prognosis and chemoresistance, and detection of small residual tumors on ovarian cancer. This review article provides an overview on recent research on CTCs in ovarian cancer, with special focus on the clinical application of CTC tests.

Nanomaterial-based biosensor developing as a route toward in vitro diagnosis of early ovarian cancer

The grand challenges of ovarian cancer early diagnosis have led to an alarmingly high mortality rate from ovarian cancer (OC) in the past half century. In vitro diagnosis (IVD) has great potential in the early diagnosis of OC through non-invasive and dynamic analysis of biomarkers. However, common IVDs often fail to provide reliable test results due to lack of sensitivity, specificity, and convenience. In recent years, the discovery of new biomarkers and the progress of nanomaterials can solve the shortcomings of traditional IVD for early OC. These emerging biosensors based on nanomaterials offer great improvements in convenience, speed, selectivity, and sensitivity of IVD. In this review, we firstly systematically summarized the limits of commercial IVD biosensors of OC and the latest discovery of new biomarkers for OC. The representative optimization strategies for six potential ovarian cancer biomarkers are systematically discussed with emphasis on nanomaterial selection and the design of detection principles. Then, various strategies adopted by emerging biosensors based on nanomaterials are also introduced in detail, including optical, electrochemical, microfluidic, and surface plasmon sensors. Finally, current challenges of early OC IVD are proposed, and future research directions on this promising field are also discussed.

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Failure to diagnose OC early will lead to high mortality.

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The detection of OC-related biomarkers by IVD method will achieve early diagnosis of OC.

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The development of nanomaterials-based biosensors is expected to enhance efficiency of detection.

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Strategies and progress for nanomaterials-based biosensors are systematically reviewed.

The Progress of the Specific and Rapid Genetic Detection Methods for Ovarian Cancer Diagnosis and Treatment

Cancer is a public health problem that threatens human health. Due to the lack of specific and rapid diagnosis and treatment methods, the 5-year survival rate of patients has not been effectively improved in the past 10 years. Abnormal gene expression is closely related to the occurrence and development of cancer. Cancer diagnosis and treatment methods based on genetic testing have received extensive attention in recent years. It is essential to explore specific and rapid cancer genetic testing methods. Taking ovarian cancer as an example, we reviewed the progress of specific and rapid nucleic acid detection methods related to cancer risk assessment, low-abundance mutation detection, and methylation detection, to provide new strategies and ideas for related research.

The Current and Future States of Screening in Gynecologic Cancers

Gynecologic cancers contribute to a significant portion of cancer morbidity and mortality among women in the United States and across the globe. This article provides a comprehensive review of current screening guidelines and novel techniques that have promise in the prevention and early detection of gynecologic cancers in the future. The authors anticipate a move toward less invasive testing modalities, use of cancer biomarkers, and the prevention and treatment of high-risk factors such as human papilloma virus infection and obesity.

Circulating p16-Positive and p16-Negative Tumor Cells Serve as Independent Prognostic Indicators of Survival in Patients with Head and Neck Squamous Cell Carcinomas

BACKGROUND

Decisions regarding the staging, prognosis, and treatment of patients with head and neck squamous cell carcinomas (HNSCCs) are made after determining their p16 expression levels and human papillomavirus (HPV) infection status.

METHODS

We investigated the prognostic roles of p16-positive and p16-negative circulating tumor cells (CTCs) and their cell counts in HNSCC patients. We enrolled patients with locally advanced HNSCCs who received definitive concurrent chemoradiotherapy for final analysis. We performed CTC testing and p16 expression analysis before chemoradiotherapy. We analyzed the correlation between p16-positive and p16-negative CTCs and HPV genotyping, tissue p16 expression status, response to chemoradiotherapy, disease-free survival, and overall survival.

RESULTS

Forty-one patients who fulfilled the study criteria were prospectively enrolled for final analysis. The detection rates of p16-positive (>0 cells/mL blood) and p16-negative (≥3 cells/mL blood) CTCs were 51.2% (n = 21/41) and 70.7%, respectively. The best responses of chemoradiotherapy and the p16 positivity of CTCs are independent prognostic factors of disease progression, with hazard ratios of 1.738 (95% confidence interval (CI): 1.031-2.927), 5.497 (95% CI: 1.818-16.615), and 0.176 (95% CI: 0.056-0.554), respectively. The p16 positivity of CTCs was a prognostic factor for cancer death, with a hazard ratio of 0.294 (95% CI: 0.102-0.852).

CONCLUSIONS

The p16-positive and p16-negative CTCs could predict outcomes in HNSCC patients receiving definitive chemoradiotherapy. This non-invasive CTC test could help stratify the risk and prognosis before chemoradiotherapy in clinical practice and enable us to perform de-intensifying therapies.

Circulating Tumor Cells: Technologies and Their Clinical Potential in Cancer Metastasis

Circulating tumor cells (CTCs) are single cells or clusters of cells within the circulatory system of a cancer patient. While most CTCs will perish, a small proportion will proceed to colonize the metastatic niche. The clinical importance of CTCs was reaffirmed by the 2008 FDA approval of CellSearch^®, a platform that could extract EpCAM-positive, CD45-negative cells from whole blood samples. Many further studies have demonstrated the presence of CTCs to stratify patients based on overall and progression-free survival, among other clinical indices. Given their unique role in metastasis, CTCs could also offer a glimpse into the genetic drivers of metastasis. Investigation of CTCs has already led to groundbreaking discoveries such as receptor switching between primary tumors and metastatic nodules in breast cancer, which could greatly affect disease management, as well as CTC-immune cell interactions that enhance colonization. In this review, we will highlight the growing variety of isolation techniques for investigating CTCs. Next, we will provide clinically relevant context for CTCs, discussing key clinical trials involving CTCs. Finally, we will provide insight into the future of CTC studies and some questions that CTCs are primed to answer.

Future Screening Prospects for Ovarian Cancer

Simple Summary

Ovarian cancer (OC) has the highest mortality rate of all gynecological cancers. It is usually diagnosed in late stages (FIGO III-IV), and therefore, overall survival is very poor. If diagnosed at the early stages, ovarian cancer has a 90% five-year survival rate. Liquid biopsy has a good potential to improve early ovarian cancer detection and is discussed in this review.

Abstract

Current diagnostic tools used in clinical practice such as transvaginal ultrasound, CA 125, and HE4 are not sensitive and specific enough to diagnose OC in the early stages. A lack of early symptoms and an effective asymptomatic population screening strategy leads to a poor prognosis in OC. New diagnostic and screening methods are urgently needed for early OC diagnosis. Liquid biopsies have been considered as a new noninvasive and promising method, using plasma/serum, uterine lavage, and urine samples for early cancer detection. We analyzed recent studies on molecular biomarkers with specific emphasis on liquid biopsy methods and diagnostic efficacy for OC through the detection of circulating tumor cells, circulating cell-free DNA, small noncoding RNAs, and tumor-educated platelets.

A PLGA nanofiber microfluidic device for highly efficient isolation and release of different phenotypic circulating tumor cells based on dual aptamers

The isolation of specific and sensitive circulating tumor cells (CTCs) is significant for applying them in cancer diagnosis and monitoring. In this work, dual aptamer-modified poly(lactic-co-glycolic acid) (PLGA) nanofiber-based microfluidic devices were fabricated to achieve the highly efficient capture and specific release of epithelial and mesenchymal CTCs of ovarian cancer. Dual aptamer targeting epithelial cell adhesion molecules (EpCAM) and N-cadherin proteins to improve the capture sensitivity, bovine serum albumin (BSA) to guarantee the capture purity and the nanofibers to increase the capture efficiency via synchronously and effectively capturing the epithelial and mesenchymal CTCs with good capture specificity and sensitivity from blood samples were used. We used the target cells including the ovarian cancer A2780 cells (N-cadherin-high, EpCAM-low) and OVCAR-3 cells (EpCAM-high, N-cadherin-low) to test the devices, which exhibited good capture efficiency (91% for A2780 cells, 89% for OVCAR-3 cells), release efficiency (95% for A2780 cells, 88% for OVCAR-3 cells), and sensitivity for rare cells (92% for A2780 cells, 88% for OVCAR-3 cells). Finally, the clinical blood samples of ovarian cancer patients were detected by the PLGA nanofiber-based microfluidic device, and 1 to 13 CTCs were successfully confirmed to be captured with the help of immunofluorescence staining identification. The results exhibited that the dual aptamer-modified PLGA nanofiber-based microfluidic device used as a tool for CTC capture has the potential for clinical application to guide the diagnosis, treatment, and prognosis of ovarian cancer patients.

Comprehending the Proteomic Landscape of Ovarian Cancer: A Road to the Discovery of Disease Biomarkers

Despite recent technological advancements allowing the characterization of cancers at a molecular level along with biomarkers for cancer diagnosis, the management of ovarian cancers (OC) remains challenging. Proteins assume functions encoded by the genome and the complete set of proteins, termed the proteome, reflects the health state. Comprehending the circulatory proteomic profiles for OC subtypes, therefore, has the potential to reveal biomarkers with clinical utility concerning early diagnosis or to predict response to specific therapies. Furthermore, characterization of the proteomic landscape of tumor-derived tissue, cell lines, and PDX models has led to the molecular stratification of patient groups, with implications for personalized therapy and management of drug resistance. Here, we review single and multiple marker panels that have been identified through proteomic investigations of patient sera, effusions, and other biospecimens. We discuss their clinical utility and implementation into clinical practice.

Clinical significance of circulating tumor cell related markers in patients with epithelial ovarian cancer before and after adjuvant chemotherapy

Circulating tumor cells (CTCs) have recently been considered as new prognostic and diagnostic markers for various human cancers; however, their significance in epithelial ovarian cancer (EOC) remains to be elucidated. In this study, using quantitative real-time PCR, we evaluated the expression of EPCAM, MUC1, CEA, HE4 and CA125 mRNAs, as putative markers of CTCs, in the blood of 51 EOC patients before and/or after adjuvant chemotherapy. Our results demonstrated that, before chemotherapy, the expression of EPCAM, MUC1, CEA and HE4 mRNAs were correlated to each other. CEA expression was correlated with tumor stage (r = 0.594, p = 0.000) before chemotherapy, whereas its expression after chemotherapy was correlated with serum levels of CA125 antigen (r = 0.658, p = 0.000). HE4 mRNA showed the highest sensitivity both before and after chemotherapy (82.98% and 85.19%, respectively) and the persistence of this marker after chemotherapy was associated with advanced disease stage. The expression of CA125 mRNA had negative correlation with the other markers and with tumor stage and therapy response (evaluated by the measurement of serum CA125 antigen). Collectively, our results indicated a better clinical significance of tumor-specific markers (CEA and HE4 mRNAs) compared to epithelial-specific markers (EPCAM and MUC1 mRNAs).

Liquid Biopsy in the Clinical Management of High-Grade Serous Epithelial Ovarian Cancer-Current Use and Future Opportunities

The lack of a sensitive and specific biomarker and the limits relating to the single primary tumor sampling make it difficult to monitor high-grade serous epithelial ovarian cancer (HGS-EOC) over time and to capture those alterations that are potentially useful in guiding clinical decisions. To overcome these issues, liquid biopsy has emerged as a very promising tool for HGS-EOC. The analysis of circulating tumor DNA appears to be feasible and studies assessing specific pathogenic mutations (i.e., TP53) or copy number alterations have shown a sufficient degree of sensitivity and specificity to be realistically used to monitor the effectiveness of antitumor therapy. Liquid biopsy can also provide potential important information on the mechanisms of sensitivity and resistance, e.g., by the determination of the reversion of BRCA mutations. Perspective studies are needed to test whether the application of liquid biopsy will significantly improve HGS-EOC management and patients' survival.

Research Progress in Prognostic Factors and Biomarkers of Ovarian Cancer

Ovarian cancer is a serious threat to women's health; its early diagnosis rate is low and prone to metastasis and recurrence. The current conventional treatment for ovarian cancer is a combination of platinum and paclitaxel chemotherapy based on surgery. The recurrence and progression of ovarian cancer with poor prognosis is a major challenge in treatment. With rapid advances in technology, understanding of the molecular pathways involved in ovarian cancer recurrence and progression has increased, biomarker-guided treatment options can greatly improve the prognosis of patients. This review systematically discusses and summarizes existing and new information on prognostic factors and biomarkers of ovarian cancer, which is expected to improve the clinical management of patients and lead to effective personalized treatment.

An Automatic Platform Based on Nanostructured Microfluidic Chip for Isolating and Identification of Circulating Tumor Cells

Circulating tumor cell (CTC) test is currently used as a biomarker in cancer treatment. Unfortunately, the poor reproducibility and limited sensitivity with the CTC detection have limited its potential impact on clinical application. A reliable automated CTC detection system is therefore needed. We have designed an automated microfluidic chip-based CTC detection system and hypothesize this novel system can reliably detect CTC from clinical specimens. SKOV3 ovarian cancer cell line was used first to test the reliability of our system. Ten healthy volunteers, 5 patients with benign ovarian tumors, and 8 patients with epithelial ovarian cancer (EOC) were recruited to validate the CTC capturing efficacy in the peripheral blood. The capture rates for spiking test in SKOV3 cells were 48.3% and 89.6% by using anti-EpCAM antibody alone and a combination of anti-EpCAM antibody and anti-N-cadherin antibody, respectively. The system was sensitive to detection of low cell count and showed a linear relationship with the cell counts in our test range. The sensitivity and specificity were 62.5% and 100% when CTC was used as a biomarker for EOC. Our results demonstrated that this automatic CTC platform has a high capture rate and is feasible for detection of CTCs in EOC.

Enrichment and detection method for the prognostic value of circulating tumor cells in ovarian cancer: A meta-analysis

OBJECTIVES

Recent studies have revealed that circulating tumor cells (CTCs) might predict bad prognosis, but the results were conflicting. Sampling time, treatment, enrichment method and detection method also varied. We aimed to evaluate whether patients with CTCs in peripheral blood have bad survival outcomes with consideration of the above four aspects.

METHODS

Relevant studies were searched on Pubmed, Embase and the Cochrane Library. Studies of CTCs involving survival data available were identified for a systematic review and meta-analysis. HRs and 95% CIs for PFS and OS were extracted directly or from the Kaplan-Meier survival curves by the Engauge Digitizer v4.1. Subgroup analyses were performed to evaluate the effect of sampling time, treatment, enrichment method and detection method.

RESULTS

Two clinical trials and thirteen retrospective studies with a total of 1285 patients were included. CTCs significantly correlated with OS (HR = 1.77, 95%CI:1.42-2.21, p < 0.00001 and PFS (HR = 1.53, 95%CI:1.26-1.86, p < 0.0001). Subgroup analyses showed that CTCs were significant associated with OS in the "Pre-therapy" subgroup (HR = 1.79, 95%CI:1.43-2.24, p < 0.00001), the "Surgery" group (HR = 1.82, 95%CI:1.42-2.33, p < 0.00001), and the "RT-PCR"subgroup (HR = 2.29, 95%CI:1.53-3.42, p < 0.0001). While for enrichment method, CTCs significantly correlated with OS in the"Physical method" subgroup (HR = 1.94, 95%CI:1.21-3.09, p = 0.006) and the "Immunological method" subgroup (HR = 1.84, 95%CI:1.37-2.48, p < 0.0001).

CONCLUSIONS

The presence of CTCs prior to the treatment indicated worse OS and PFS and CTCs might be predictive biomarker for ovarian cancer patients . CTCs detected using RT-PCR seem to be associated with poorer OS and PFS in patients with ovarian cancer.

A Novel Liquid Biopsy Strategy to Detect Small Amounts of Cancer Cells Using Cancer-Specific Replication Adenoviruses

Circulating tumor cells (CTCs) are a promising source of clinical and biological cancer information and can be a material for liquid biopsy. However, detecting and capturing these cells remains a challenge. Various biological factors (e.g., cell surface proteins, cell size, deformability, or dielectrophoresis) have been applied to detect CTCs. Cancer cells dramatically change their characteristics during tumorigenesis and metastasis. Hence, defining a cell as malignant using such a parameter is difficult. Moreover, immortality is an essential characteristic of cancer cells. Telomerase elongates telomeres and plays a critical role in cellular immortality and is specifically activated in cancer cells. Thus, the activation of telomerase can be a good fingerprint for cancer cells. Telomerase cannot be recognized by antibodies in living cells because it is a nuclear enzyme. Therefore, telomerase-specific replication adenovirus, which expresses the green fluorescent protein, has been applied to detect CTCs. This review explores the overview of this novel technology and its application in gynecological cancers.

High-throughput approaches for precision medicine in high-grade serous ovarian cancer

High-grade serous carcinoma (HGSC) is the most prevalent and aggressive subtype of ovarian cancer. The large degree of clinical heterogeneity within HGSC has justified deviations from the traditional one-size-fits-all clinical management approach. However, the majority of HGSC patients still relapse with chemo-resistant cancer and eventually succumb to their disease, evidence that further work is needed to improve patient outcomes. Advancements in high-throughput technologies have enabled novel insights into biological complexity, offering a large potential for informing precision medicine efforts. Here, we review the current landscape of clinical management for HGSC and highlight applications of high-throughput biological approaches for molecular subtyping and the discovery of putative blood-based biomarkers and novel therapeutic targets. Additionally, we present recent improvements in model systems and discuss how their intersection with high-throughput platforms and technological advancements is positioned to accelerate the realization of precision medicine in HGSC.

Enrichment and detection of circulating tumor cells by immunomagnetic beads and flow cytometry

OBJECTIVE

The purpose of the article is to establish a quick enrichment and detection method using immunomagnetic beads and flow cytometry to analyze circulating tumor cells (CTCs) in the peripheral blood.

RESULTS

After incubation with CD326-PE and CD45-APC antibodies, more than 60% MCF7 cells in M-Buffer could be detected while less than 10% of the same cells could be detected by flow cytometry (FCM) if spiked into blood. However, in combination with CD326 and CD45 immunomagnetic beads, detection rate of MCF7 cells in blood reached 57%. For circulating tumor cells, enrichment by CD326 and CD45 immunomagnetic beads improve the detection rate from nearly undetectable to more than 24.14%.

CONCLUSIONS

Live CTCs in peripheral blood can be effectively and sensitively detected by using a combination of immunomagnetic beads (CD45 and CD326) and flow cytometry.

Liquid Biopsy is Instrumental for 3PM Dimensional Solutions in Cancer Management

One in every four deaths is due to cancer in Europe. In view of its increasing incidence, cancer became the leading cause of death and disease burden in Denmark, France, the Netherlands, and the UK. Without essential improvements in cancer prevention, an additional 775,000 cases of annual incidence have been prognosed until 2040. Between 1995 and 2018, the direct costs of cancer doubled from EUR 52 billion to EUR 103 billion in Europe, and per capita health spending on cancer increased by 86% from EUR 105 to EUR 195 in general, whereby Austria, Germany, Switzerland, Benelux, and France spend the most on cancer care compared to other European countries. In view of the consequent severe socio-economic burden on society, the paradigm change from a reactive to a predictive, preventive, and personalized medical approach in the overall cancer management is essential. Concepts of predictive, preventive, and personalized medicine (3PM) demonstrate a great potential to revise the above presented trends and to implement cost-effective healthcare that benefits the patient and society as a whole. At any stage, application of early and predictive diagnostics, targeted prevention, and personalization of medical services are basic pillars making 3PM particularly attractive for the patients as well as ethical and cost-effective healthcare. Optimal 3PM approach requires novel instruments such as well-designed liquid biopsy application. This review article highlights current achievements and details liquid biopsy approaches specifically in cancer management. 3PM-relevant expert recommendations are provided.

Current insights into the metastasis of epithelial ovarian cancer - hopes and hurdles

BACKGROUND

Ovarian cancer is the most lethal gynecologic cancer and the fifth leading cause of cancer-related mortality in women worldwide. Despite various attempts to improve the diagnosis and therapy of ovarian cancer patients, the survival rate for these patients is still dismal, mainly because most of them are diagnosed at a late stage. Up to 90% of ovarian cancers arise from neoplastic transformation of ovarian surface epithelial cells, and are usually referred to as epithelial ovarian cancer (EOC). Unlike most human cancers, which are disseminated through blood-borne metastatic routes, EOC has traditionally been thought to be disseminated through direct migration of ovarian tumor cells to the peritoneal cavity and omentum via peritoneal fluid. It has recently been shown, however, that EOC can also be disseminated through blood-borne metastatic routes, challenging previous thoughts about ovarian cancer metastasis.

CONCLUSIONS

Here, we review our current understanding of the most updated cellular and molecular mechanisms underlying EOC metastasis and discuss in more detail two main metastatic routes of EOC, i.e., transcoelomic metastasis and hematogenous metastasis. The emerging concept of blood-borne EOC metastasis has led to exploration of the significance of circulating tumor cells (CTCs) as novel and non-invasive prognostic markers in this daunting cancer. We also evaluate the role of tumor stroma, including cancer associated fibroblasts (CAFs), tumor associated macrophages (TAMs), endothelial cells, adipocytes, dendritic cells and extracellular matrix (ECM) components in EOC growth and metastasis. Lastly, we discuss therapeutic approaches for targeting EOC. Unraveling the mechanisms underlying EOC metastasis will open up avenues to the design of new therapeutic options. For instance, understanding the molecular mechanisms involved in the hematogenous metastasis of EOC, the biology of CTCs, and the detailed mechanisms through which EOC cells take advantage of stromal cells may help to find new opportunities for targeting EOC metastasis.

Characterization of a novel automated microfiltration device for the efficient isolation and analysis of circulating tumor cells from clinical blood samples

The detection and analysis of circulating tumor cells (CTCs) may enable a broad range of cancer-related applications, including the identification of acquired drug resistance during treatments. However, the non-scalable fabrication, prolonged sample processing times, and the lack of automation, associated with most of the technologies developed to isolate these rare cells, have impeded their transition into the clinical practice. This work describes a novel membrane-based microfiltration device comprised of a fully automated sample processing unit and a machine-vision-enabled imaging system that allows the efficient isolation and rapid analysis of CTCs from blood. The device performance was characterized using four prostate cancer cell lines, including PC-3, VCaP, DU-145, and LNCaP, obtaining high assay reproducibility and capture efficiencies greater than 93% after processing 7.5 mL blood samples spiked with 100 cancer cells. Cancer cells remained viable after filtration due to the minimal shear stress exerted over cells during the procedure, while the identification of cancer cells by immunostaining was not affected by the number of non-specific events captured on the membrane. We were also able to identify the androgen receptor (AR) point mutation T878A from 7.5 mL blood samples spiked with 50 LNCaP cells using RT-PCR and Sanger sequencing. Finally, CTCs were detected in 8 out of 8 samples from patients diagnosed with metastatic prostate cancer (mean ± SEM = 21 ± 2.957 CTCs/mL, median = 21 CTCs/mL), demonstrating the potential clinical utility of this device.

Intravenous 5-fluoro-2'-deoxycytidine administered with tetrahydrouridine increases the proportion of p16-expressing circulating tumor cells in patients with advanced solid tumors

PURPOSE

Following promising responses to the DNA methyltransferase (DNMT) inhibitor 5-fluoro-2'-deoxycytidine (FdCyd) combined with tetrahydrouridine (THU) in phase 1 testing, we initiated a non-randomized phase 2 study to assess response to this combination in patients with advanced solid tumor types for which tumor suppressor gene methylation is potentially prognostic. To obtain pharmacodynamic evidence for DNMT inhibition by FdCyd, we developed a novel method for detecting expression of tumor suppressor protein p16/INK4A in circulating tumor cells (CTCs).

METHODS

Patients in histology-specific strata (breast, head and neck [H&N], or non-small cell lung cancers [NSCLC] or urothelial transitional cell carcinoma) were administered FdCyd (100 mg/m2) and THU (350 mg/m2) intravenously 5 days/week for 2 weeks, in 28-day cycles, and progression-free survival (PFS) rate and objective response rate (ORR) were evaluated. Blood specimens were collected for CTC analysis.

RESULTS

Ninety-three eligible patients were enrolled (29 breast, 21 H&N, 25 NSCLC, and 18 urothelial). There were three partial responses. All strata were terminated early due to insufficient responses (H&N, NSCLC) or slow accrual (breast, urothelial). However, the preliminary 4-month PFS rate (42%) in the urothelial stratum exceeded the predefined goal-though the ORR (5.6%) did not. An increase in the proportion of p16-expressing cytokeratin-positive CTCs was detected in 69% of patients evaluable for clinical and CTC response, but was not significantly associated with clinical response.

CONCLUSION

Further study of FdCyd + THU is potentially warranted in urothelial carcinoma but not NSCLC or breast or H&N cancer. Increase in the proportion of p16-expressing cytokeratin-positive CTCs is a pharmacodynamic marker of FdCyd target engagement.

Clinical relevance of circulating tumor cells in ovarian, fallopian tube and peritoneal cancer

Purpose

Presence of circulating tumor cells (CTCs) is associated with impaired clinical outcome in several solid cancers. Limited data are available on the significance of CTCs in gynaecological malignancies. The aims of the present study were to evaluate the dynamics of CTCs in patients with ovarian, fallopian tube and peritoneal cancer during chemotherapy and to assess their clinical relevance.

Methods

43 patients with ovarian, fallopian tube and peritoneal cancer were included into this prospective study. Patients received chemotherapy according to national guidelines. CTC analysis was performed using the CellSearch system prior to chemotherapy, after three and six cycles.

Results

In 26% of the patients, ≥ 1CTC per 7.5 ml of blood was detected at baseline (17% of patients with de novo disease, compared to 35% in recurrent patients). Presence of CTCs did not correlate with other factors. After three cycles of therapy, CTC positivity rate declined to 4.8%. After six cycles, no patient showed persistent CTCs. Patients with ≥ 1 CTC at baseline had significantly shorter overall survival and progression-free survival compared to CTC-negative patients (OS: median 3.1 months vs. not reached, p = 0.006, PFS: median 3.1 vs. 23.1 months, p = 0.005). When only the subgroup with newly diagnosed cancer was considered, the association between CTC status and survival was not significant (OS: mean 17.4 vs. 29.0 months, p = 0.192, PFS: 14.3 vs. 26.9 months, p = 0.085). Presence of ≥ 1 CTC after three cycles predicted shorter OS in the entire patient cohort (p < 0.001).

Conclusions

Hematogenous tumor cell dissemination is a common phenomenon in ovarian, fallopian tube and peritoneal cancer. CTC status before start of systemic therapy correlates with clinical outcome. Chemotherapy leads to a rapid decline in CTC counts; further research is needed to evaluate the clinical value of CTC monitoring after therapy.

Liquid biopsy in ovarian cancer

Ovarian cancer has the worst survival rate because it is typically diagnosed at advanced stage. Despite treatment, the disease commonly recurs due to chemo-resistance. Liquid biopsy, based on minimally invasive blood tests, has the advantage of following tumor evolution in real time, offering novel insights on cancer prevention and treatment. Circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), circulating cell-free microRNAs (cfmiRNAs) and circulating exosomes represent the major components of liquid biopsy. In this chapter, we provide an overview of recent research on CTCs, ctDNA, cfmiRNAs and exosomes in ovarian cancer. We also focus on the clinical value of liquid biopsy in early diagnosis, prognosis, treatment response, as well as screening in the general population.

CYPA promotes the progression and metastasis of serous ovarian cancer (SOC) in vitro and in vivo

Ovarian cancer (OC) is a type of gynaecological malignancy with high mortality in females. Serous ovarian cancer (SOC) is a distinct subtype of OC with poor early diagnosis. Given the limitations of traditional therapies, such as chemotherapy, targeted treatment is therefore a promising therapy to improve the survival rate of SOC patients. Cyclophilin A (CYPA) is a member of Cyclophilin family and thought to participates in multiple cellular processes such as cell transduction and immune modulation. Recently, various of studies indicated that CYPA has critical impact on cancer progression. CYPA could regulate cell proliferation, invasion, and chemoresistance of multiple types of cancers. However, it is still unclear whether it could affect ovarian cancer. In this study, we demonstrated that CYPA was highly expressed in SOC tissues compared with adjacent tissues. Further, CYPA was significantly associated with clinical stage and lymphnode metastasis of SOC patients. Additionally, data indicated that knockdown of CYPA by its shRNA dramatically reduces migration and invasion capacity of SOC cells in vitro and blocks tumor metastasis in vivo. Our study investigates the involvement of CYPA in the progression and metastasis of SOC, and therefore provides CYPA as a promising therapeutic target for SOC treatment.

Liquid biopsy in ovarian cancer using circulating tumor DNA and cells: Ready for prime time?

Liquid biopsies hold the potential to inform cancer patient prognosis and to guide treatment decisions at the time when direct tumor biopsy may be impractical due to its invasive nature, inaccessibility and associated complications. Specifically, circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs) have shown promising results as companion diagnostic biomarkers for screening, prognostication and/or patient surveillance in many cancer types. In ovarian cancer (OC), CTC and ctDNA analysis allow comprehensive molecular profiling of the primary, metastatic and recurrent tumors. These biomarkers also correlate with overall tumor burden and thus, they provide minimally-invasive means for patient monitoring during clinical course to ascertain therapy response and timely treatment modification in the context of disease relapse. Here, we review recent reports of the potential clinical value of CTC and ctDNA in OC, expatiating on their use in diagnosis and prognosis. We critically appraise the current evidence, and discuss the issues that still need to be addressed before liquid biopsies can be implemented in routine clinical practice for OC management.

High-Throughput Automated Microscopy of Circulating Tumor Cells

Circulating tumor cells (CTCs) have the potential of becoming the gold standard marker for cancer diagnosis, prognosis and monitoring. However, current methods for its isolation and characterization suffer from equipment variability and human operator error that hinder its widespread use. Here we report the design and construction of a fully automated high-throughput fluorescence microscope that enables the imaging and classification of cancer cells that were labeled by immunostaining procedures. An excellent agreement between our machine vision-based approach and a state-of-the-art microscopy equipment was achieved. Our integral approach provides a path for operator-free and robust analysis of cancer cells as a standard clinical practice.