Prognostic Value of Circulating Tumor Cells in Ovarian Cancer: A Meta-Analysis

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.

Current methodologies to detect circulating tumor cells: a focus on ovarian cancer

Identification of circulating tumor cells (CTC) in liquid biopsies opens a window of opportunities for the optimization of clinical management of oncologic patients. In ovarian cancer (OC), which involves atypical routes of metastatic spread, CTC analyses may also offer novel insights about the mechanisms behind malignant progression of the disease. However, current methodologies struggle to precisely define CTC number in the peripheral blood of OC patients, and the isolation of viable cells for further characterization is still challenging. The biggest limitation is the lack of methodological standardization for OC CTC detection, preventing comprehensive definition of their clinical potential required for the transfer to practice. Here we describe and compare methods for CTC analysis that have been implemented for OC thus far, discussing pros, cons and improvements needed. We identify biophysical separation approaches as optimal for CTC enrichment. On the other hand, the identification of specific tumor antigens or gene transcripts, despite displaying drawbacks related to tumor heterogeneity, still remains the best approach for OC CTC detection.

The Plasticity of Circulating Tumor Cells in Ovarian Cancer During Platinum-containing Chemotherapy

BACKGROUND

Circulating tumor cells (CTCs) are a potential source of metastases and relapses. The data on the ovarian cancer (OC) CTCs molecular characteristics are limited.

OBJECTIVE

To assess the TGFβ, CXCL2, VEGFA and ERCC1 expression in two OC CTC subpopulations before and during chemotherapy (CT), and its relation to clinical characteristics.

METHODS

Two CTCs subpopulations (EpCAM+CK18+E-cadherin+; EpCAM+CK18+Vimentin+) were enriched using immunomagnetic separation before treatment and after 3 cycles of platinum-containing CT. Expression of mRNA was assessed using RT-qPCR.

RESULTS

The study included 31 I-IV stage OC patients. During CT, TGFβ levels increased in both fractions (p=0.054) compared with the initial levels. ERCC1 expression in E-cadherin+ CTCs was higher during neoadjuvant than adjuvant CT (p=0.004). CXCL2 level in E-cadherin+ CTCs increased (p=0.038) during neoadjuvant CT compared with the initial. TGF-β expression in vimentin+ CTCs during CT was negatively correlated to disease stage (p=0.003). Principal component analysis before CT revealed a component combining VEGFA, TGFβ, CXCL2, and a component with ERCC1 and VEGFA; during CT, component 1 contained ERCC1 and VEGFA, component 2 - TGFβ and CXCL2 in both fractions. Increased ERCC1 expression in E-cadherin+ CTCs during CT was associated with decreased progression-free survival (PFS) (HR 1.11 (95% CI 1.03-1.21, p=0.009) in multivariate analysis.

CONCLUSION

EpCAM+ OC CTCs are phenotypically heterogeneous, which may reflect variability in their metastatic potential. CT changes the molecular characteristics of CTCs. Expression of TGFβ in EpCAM+ CTCs increases during CT. High ERCC1 expression in EpCAM+CK18+E-cadherin+ CTCs during CT is associated with decreased PFS in OC.

Lymphovascular space invasion as a prognostic factor of epithelial ovarian cancer: a multicenter study by the FRANCOGYN group

BACKGROUND

The presence of lymphovascular space invasion (LVSI) is not yet included in international recommendations neither as a prognostic factor nor as a parameter for the decision to use adjuvant chemotherapy in FIGO stage I/IIa ovarian cancer (OC).

OBJECTIVE

This study set out to evaluate the impact of LVSI on Overall Survival (OS) and Recurrence-Free Survival (RFS) in patients managed for epithelial OC.

DESIGN

Retrospective multicenter study by the research group FRANCOGYN between January 2001 and December 2018. All patients managed for epithelial OC surgery and for whom histological slides for the review of LVSI were available, were included. The characteristics of patients with LVSI (LVSI group) were compared to those without LVSI (No-LVSI group). A Cox analysis for OS and RFS analysis was performed in all the populations.

SETTING

French multicenter tertiary care centers RESULTS: Over the study period, 852 patients were included in the 13 institutions. Among them, 289 patients had LVSI (33.9%). There was a significant difference in the distribution of LVSI between early and advanced stages (p  <  0.001). LVSI was an independent predictive factor for poorer Overall and Recurrence-Free Survival. LVSI affected OS (p  <  0.001) and RFS (p  <  0.001), LVSI affected OS and RFS for early stages (p  =  0.001; p  =  0.001, respectively) and also for advanced stages (p  =  0.01; p  =  0.009, respectively).

CONCLUSION

The presence of LVSI in epithelial ovarian epithelial tumors has an impact on OS and RFS and should be included in the routine pathology examination to adapt therapeutic management, especially for women in the early stages of the disease.

Reducing Ovarian Cancer Mortality Through Early Detection: Approaches Using Circulating Biomarkers

More than two-thirds of all women diagnosed with epithelial ovarian cancer (EOC) will die from the disease (>14,000 deaths annually), a fact that has not changed considerably in the last three decades. Although the 5-year survival rates for most other solid tumors have improved steadily, ovarian cancer remains an exception, making it the deadliest of all gynecologic cancers and five times deadlier than breast cancer. When diagnosed early, treatment is more effective, with a 5-year survival rate of up to 90%. Unfortunately, most cases are not detected until after the cancer has spread, resulting in a dismal 5-year survival rate of less than 30%. Current screening methods for ovarian cancer typically use a combination of a pelvic examination, transvaginal ultrasonography, and serum cancer antigen 125 (CA125), but these have made minimal impact on improving mortality. Thus, there is a compelling unmet need to develop new molecular tools that can be used to diagnose early-stage EOC and/or assist in the clinical management of the disease after a diagnosis, given that more than 220,000 women are living with ovarian cancer in the United States and are at risk of recurrence. Here, we discuss the state of advancing liquid-based approaches for improving the early detection of ovarian cancer.See all articles in this Special Collection Honoring Paul F. Engstrom, MD, Champion of Cancer Prevention.

Prognostic relevance of longitudinal HGF levels in serum of patients with ovarian cancer

The pleiotropic protein hepatocyte growth factor (HGF) is the only known ligand of the tyrosine kinase mesenchymal–epithelial transition (cMET) receptor. The HGF/cMET pathway mediates invasion and migration of ovarian cancer cells, and upregulation of HGF/cMET pathway components has been associated with poor prognosis. This study investigated the clinical relevance of circulating HGF in serum of patients with ovarian cancer. Serum HGF (sHGF) was determined by enzyme‐linked immunosorbent assay in a total of 471 serum samples from 82 healthy controls and 113 patients with ovarian cancer (88.5% with ≥ FIGO III). Patient samples were collected at primary diagnosis and at four follow‐up time points throughout treatment and at disease recurrence. Patients with ovarian cancer showed elevated median sHGF levels at primary diagnosis, and sHGF levels transiently increased after surgery and normalized in the course of chemotherapy, even dropping below initial baseline. Higher levels of sHGF were an independent predictor for shorter overall survival (OS) (a) at primary diagnosis (HR = 0.41, 95% CI: 0.22–0.78, P = 0.006), (b) at longitudinal follow‐up time points (after surgery and before/during/after chemotherapy), (c) along the patients’ individual dynamics (HR = 0.21, 95% CI: 0.07–0.63, P = 0.005), and (d) among a subgroup analysis of patients with BRCA1/2 wild‐type ovarian cancer. This is the first study proposing sHGF as an independent prognostic biomarker for ovarian cancer at primary diagnosis and in the course of platinum‐based chemotherapy, irrespective of the postoperative residual disease after surgical debulking. sHGF could be implemented into clinical diagnostics as a CA125 auxiliary tumor marker for individualized prognosis stratification and sHGF‐guided therapy monitoring.

Combined detection and subclass characteristics analysis of CTCs and CTECs by SE-iFISH in ovarian cancer

Objective

Hematogenous metastasis is essential for the progression of ovarian cancer (OC), and circulating tumor cells (CTCs) are part of the metastatic cascade. However, the detection rate of CTC is low due to the use of less sensitive detection methods. Therefore, this study aimed to detect CTCs and circulating tumorigenic endothelial cells (CTECs) in patients with OC using subtraction enrichment and immunostaining and fluorescence in situ hybridization (SE-iFISH).

Methods

We enrolled a total of 56 subjects, including 20 OC patients and 36 ovarian benign tumor patients. CTCs and CTECs were captured by subtraction enrichment (SE) and counted and classified according to immunofluorescence staining of tumor markers (TMs) carbohydrate antigen 125 (CA125) and human epididymis protein 4 (HE4) combined with fluorescence in situ hybridization (iFISH) of chromosome 8 (Chr8) aneuploidy. The diagnostic value and subtype characteristics of CTCs and CTECs were investigated.

Results

The detection rate of CTCs by SE-iFISH was high. Compared with CA125 and HE4, Chr8 aneuploidy was the major identification feature of CTC. CTC counts in OC were statistically higher than those in benign groups. CTC and CTEC with ≥pentaploidy were detected in both groups, illustrating the poor diagnostic value of CTC or CTEC. Distributions of triploid and tetraploid CTC subtypes were significantly different, and combined detection of triploid and tetraploid CTCs showed the best diagnostic value. In contrast, the distribution of CTECs in the OC and benign groups had no statistically significant difference. Small CTCs accounted for over 1/3 of the total CTC count. We also found that small CTCs and CTECs primarily comprised triploid cells, while large CTCs and CTECs mainly comprised pentaploidy and beyond.

Conclusions

The application of SE-iFISH offered a more comprehensive understanding of heterogeneous CTCs and CTECs in OC. Analysis of subclass characteristics of the CTCs and CTECs according to Chr8 aneuploidy and cell size may broaden their potential clinical utility and deepen mechanistic studies in OC.

Liquid biopsy in ovarian cancer: Catching the silent killer before it strikes

Epithelial ovarian cancer (EOC) is the most lethal gynaecological malignancy in the western world. The majority of women presenting with the disease are asymptomatic and it has been dubbed the "silent killer". To date there is no effective minimally invasive method of stratifying those with the disease or screening for the disease in the general population. Recent molecular and pathological discoveries, along with the advancement of scientific technology, means there is a real possibility of having disease-specific liquid biopsies available within the clinical environment in the near future. In this review we discuss these discoveries, particularly in relation to the most common and aggressive form of EOC, and their role in making this possibility a reality.

Isolation and Enumeration of CTC in Colorectal Cancer Patients: Introduction of a Novel Cell Imaging Approach and Comparison to Cellular and Molecular Detection Techniques

Circulating tumour cells (CTC) were proven to be prognostically relevant in cancer treatment, e.g., in colorectal cancer (CRC). This study validates a molecular detection technique through using a novel cell imaging approach for CTC detection and enumeration, in comparison to a size-based cellular and correlated the data to clinico-pathological characteristics. Overall, 57 CRC patients were recruited for this prospective study. Blood samples were analysed for CTCs by three methods: (1) Epithelial marker immunofluorescence staining combined with automated microscopy using the NYONE^® cell imager; (2) isolation by size using membrane filtration with the ScreenCell^® Cyto IS device and immunofluorescence staining; (3) detection by semi-quantitative Cytokeratin-20 RT-qPCR. Enumeration data were compared and correlated with clinic-pathological parameters. CTC were detected by either approach; however, with varying positivity rates: NYONE^® 36.4%, ScreenCell^® 100%, and PCR 80.5%. All methods revealed a positive correlation of CTC presence and higher tumour burden, which was most striking using the ScreenCell^® device. Generally, no intercorrelation of CTC presence emerged amongst the applied techniques. Overall, enumeration of CTC after isolation by size demonstrated to be the most reliable strategy for the detection of CTC in CRC patients. Ongoing studies will have to unravel the prognostic value of this finding, and validate this approach in a larger cohort.

A Pilot Study of the Predictive Potential of Chemosensitivity and Gene Expression Assays Using Circulating Tumour Cells from Patients with Recurrent Ovarian Cancer

Circulating tumour cells (CTCs) from liquid biopsies are under current investigation in several cancers, including epithelial ovarian cancer (EOC) but face significant drawbacks in terms of non-standardised methodology, low viable cell numbers and accuracy of CTC identification. In this pilot study, we report that chemosensitivity assays using liquid biopsy-derived metastatic EOC CTCs, from 10 patients, nine with stage IIIC and one with stage IV disease, in progression after systemic chemotherapy, submitted for hypoxic isolated abdominal perfusion (HAP), are both feasible and useful in predicting response to therapy. Viable metastatic EOC CTCs (>5 cells/mL for all 10 blood samples), enriched by transient culture and identified by reverse transcription polymerase chain reaction (RT-PCR) and indirect immunofluorescence (IF), were subjected to flow cytometry-based Annexin V-PE assays for chemosensitivity to several chemotherapeutic agents and by RT-PCR for tumour gene expression profiling. Using a cut-off value of >80% cell death, CTC chemosensitivity tests were predictive of patient RECIST 1.1 responses to HAP therapy associated with 100% sensitivity, 50% specificity, 33% positive predictive, 100% negative predictive and 60% accuracy values. We propose that the methodology employed in this study is feasible and has the potential to predict response to therapy, setting the stage for a larger study.

Prognostic value of circulating tumor cells detected with the CellSearch system in esophageal cancer patients: a systematic review and meta-analysis

Background

Esophageal carcinoma (EC) is the seventh-most prevalent tumor in the world, which is still one of the primary causes of tumor-related death. Identifying noteworthy biomarkers for EC is particularly significant in guiding effective treatment. Recently, circulating tumor cells (CTCs) in peripheral blood (PB) were intensively discussed as prognostic markers in patients with EC. However, an ongoing controversy still exists regarding the prognostic significance of CTCs determined by the CellSearch system in EC sufferers. This meta-analysis was designed to approach this topic.

Methods

We systematically conducted searches using PubMed, Medline, Web of Science and the Cochrane Library for relevant studies, which were published through February 20, 2020. Using the random-effects model, our study was performed in Review Manager software, with odds ratios (ORs), risk ratios (RRs), hazard ratios (HRs) and 95% confidence intervals (CIs) as the effect values.

Results

Totally 7 articles were finally included in this study. For clinicopathological characteristics, the pooled results on TNM stage indicated that the III/IV group had higher rate of CTCs compared with the I/II group (OR = 1.36, 95% CI: 0.68–2.71, I² = 0%). Incidence of CTCs was higher in patients with T3/T4 stage (OR = 2.92, 95% CI: 1.31–6.51, I² = 0%) and distant metastasis group (OR = 5.18, 95% CI: 2.38–11.25, I² = 0%) compared to patients with T1/T2 stage or non-metastatic group. The pooled analysis revealed that CTC positivity detected in EC patients was correlated with poor overall survival (OS) (HR = 2.83, 95% CI:1.99–4.03, I² = 0%) and relapse-free survival (RFS) (HR = 4.71, 95% CI:2.73–8.13, I² = 0%). When pooling the estimated RR, a poor therapeutic response to chemoradiotherapy was discovered in patients with CTC positivity (RR = 1.99, 95% CI:1.73–2.29, I² = 60%).

Conclusions

In summary, our meta-analysis demonstrated that CTCs positivity determined by the CellSearch system are correlated with the prognosis of EC patients and might indicate a poor therapeutic response to chemotherapy in EC patients.

Circulating Tumor Cells Characterization Revealed TIMP1 as a Potential Therapeutic Target in Ovarian Cancer

Background: Recent studies showed a relevant role of hematogenous spread in ovarian cancer and the interest of circulating tumor cells (CTCs) monitoring as a prognosis marker. The aim of the present study was the characterization of CTCs from ovarian cancer patients, paying special attention to cell plasticity characteristics to better understand the biology of these cells. Methods: CTCs isolation was carried out in 38 patients with advanced high-grade serous ovarian cancer using in parallel CellSearch and an alternative EpCAM-based immunoisolation followed by RT-qPCR analysis to characterize these cells. Results: Epithelial CTCs were found in 21% of patients, being their presence higher in patients with extraperitoneal metastasis. Importantly, this population was characterized by the expression of epithelial markers as MUC1 and CK19, but also by genes associated with mesenchymal and more malignant features as TIMP1, CXCR4 and the stem markers CD24 and CD44. In addition, we evidenced the relevance of TIMP1 expression to promote tumor proliferation, suggesting its interest as a therapeutic target. Conclusions: Overall, we evidenced the utility of the molecular characterization of EpCAM⁺ CTCs from advanced ovarian cancer patients to identify biomarkers with potential applicability for disseminated disease detection and as therapeutic targets such as TIMP1.

The Discordance of Gene Mutations between Circulating Tumor Cells and Primary/Metastatic Tumor

Circulating tumor cells (CTCs) are an important part in the field of "liquid biopsy." However, major questions remain to be answered whether the mutations in the CTCs represent the mutations in primary tumor tissue and metastatic tumors. We compared the genetic mutations between CTCs and their matched tumors, and extracted data on the heterogeneity of the mutational status in CTCs and the change in mutations of CTCs before and during treatment. For mutations detected in single genes, we calculated the concordance of the mutations between the CTCs and primary tumor tissue. For mutations detected in multiple genes, we calculated the concordance of the mutations between the CTCs and primary/metastatic tumor tissue. The heterogeneity of the mutational status is clearly present in CTCs. For mutations detected in a single gene, the overall concordance of mutations is 53.05%. For mutations detected in multiple genes, the concordance of mutations is extremely different. The heterogeneity of the mutational status existed in single CTCs, and the mutational status of CTCs was discordant with that of tumor tissue.

Liquid Biopsies for Ovarian Carcinoma: How Blood Tests May Improve the Clinical Management of a Deadly Disease

Ovarian cancers (OvC) are frequent, with more than 22,000 new cases each year for 14,000 deaths in the United States. Except for patients with BRCA1 or BRCA2 mutations, diagnostic methods, prognostic tools, and therapeutic strategies have not much improved in the last two decades. High throughput tumor molecular analyses have identified important alterations involved in ovarian carcinoma growth and spreading. However, these data have not modified the clinical management of most of patients. Moreover, tumor sample collection requires invasive procedures not adapted to objectives, such as the screening, prediction, or assessment of treatment efficacy, monitoring of residual disease, and early diagnosis of relapse. In recent years, circulating tumor biomarkers (also known as "liquid biopsies") such as circulating tumor cells, circulating nucleotides (DNA or miRNA), or extracellular vesicles, have been massively explored through various indications, platforms, and goals, but their use has not yet been validated in routine practice. This review describes the methods of analysis and results related to liquid biopsies for ovarian epithelial cancer. The different settings that a patient can go through during her journey with OvC are explored: screening and early diagnosis, prognosis, prediction of response to systemic therapies for advanced stages, and monitoring of residual subclinical disease.

Liquid Biopsies for Ovarian Carcinoma: How Blood Tests May Improve the Clinical Management of a Deadly Disease

Ovarian cancers (OvC) are frequent, with more than 22,000 new cases each year for 14,000 deaths in the United States. Except for patients with BRCA1 or BRCA2 mutations, diagnostic methods, prognostic tools, and therapeutic strategies have not much improved in the last two decades. High throughput tumor molecular analyses have identified important alterations involved in ovarian carcinoma growth and spreading. However, these data have not modified the clinical management of most of patients. Moreover, tumor sample collection requires invasive procedures not adapted to objectives, such as the screening, prediction, or assessment of treatment efficacy, monitoring of residual disease, and early diagnosis of relapse. In recent years, circulating tumor biomarkers (also known as "liquid biopsies") such as circulating tumor cells, circulating nucleotides (DNA or miRNA), or extracellular vesicles, have been massively explored through various indications, platforms, and goals, but their use has not yet been validated in routine practice. This review describes the methods of analysis and results related to liquid biopsies for ovarian epithelial cancer. The different settings that a patient can go through during her journey with OvC are explored: screening and early diagnosis, prognosis, prediction of response to systemic therapies for advanced stages, and monitoring of residual subclinical disease.

Liquid Biopsies for Ovarian Carcinoma: How Blood Tests May Improve the Clinical Management of a Deadly Disease

Ovarian cancers (OvC) are frequent, with more than 22,000 new cases each year for 14,000 deaths in the United States. Except for patients with BRCA1 or BRCA2 mutations, diagnostic methods, prognostic tools, and therapeutic strategies have not much improved in the last two decades. High throughput tumor molecular analyses have identified important alterations involved in ovarian carcinoma growth and spreading. However, these data have not modified the clinical management of most of patients. Moreover, tumor sample collection requires invasive procedures not adapted to objectives, such as the screening, prediction, or assessment of treatment efficacy, monitoring of residual disease, and early diagnosis of relapse. In recent years, circulating tumor biomarkers (also known as "liquid biopsies") such as circulating tumor cells, circulating nucleotides (DNA or miRNA), or extracellular vesicles, have been massively explored through various indications, platforms, and goals, but their use has not yet been validated in routine practice. This review describes the methods of analysis and results related to liquid biopsies for ovarian epithelial cancer. The different settings that a patient can go through during her journey with OvC are explored: screening and early diagnosis, prognosis, prediction of response to systemic therapies for advanced stages, and monitoring of residual subclinical disease.

Liquid Biopsy in Solid Malignancy

The clinical utility of tissue biopsies in cancer management will continue to expand, especially with the evolving role of targeted therapies. "Liquid biopsy" refers to testing a patient's biofluid samples such as blood or urine to detect tumor-derived molecules and cells that can be used diagnostically and prognostically in the assessment of cancer. Many proof-of-concept and pilot studies have shown the clinical potential of liquid biopsies as diagnostic and prognostic markers which would provide a surrogate for the conventional "solid biopsy". In this review, we focus on three methods of liquid biopsy-circulating tumor cells, extracellular vesicles, and circulating tumor DNA-to provide a landscape view of their clinical applicability in cancer management and research.

Photoacoustic Flow System for the Detection of Ovarian Circulating Tumor Cells Utilizing Copper Sulfide Nanoparticles

The development of cell-specific photoacoustic (PA) contrast agents within systems of fluidic flow provides opportunities for the accurate detection of early stage cancer metastasis. Despite the promise of exogenous contrast agents for use in clinical settings, applications are currently limited by both material biocompatibility and target specificity. In this study, folic acid functionalized copper sulfide nanoparticles (FA-CuS NPs) are synthesized to enable ovarian-cancer-specific binding and PA detection in a custom flow system. Folate receptors, known to be overexpressed on the surface of ovarian cancer cells, have remained an ideal candidate for specific targeting through functionalization on nanoparticles and other contrast agents. In combination with copper sulfide nanoparticles' strong absorbance in the near-infrared (NIR), these FA-CuS NPs are an ideal contrast agent capable of being detected by photoacoustic flow cytometry. For the first time, this study shows a potential PA contrast agent to accurately identify ovarian circulating tumor cells in flow.

Liquid biopsy in ovarian cancer: recent advances on circulating tumor cells and circulating tumor DNA

Ovarian cancer remains the most lethal disease among gynecological malignancies despite the plethora of research studies during the last decades. The majority of patients are diagnosed in an advanced stage and exhibit resistance to standard chemotherapy. Circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) represent the main liquid biopsy approaches that offer a minimally invasive sample collection. Both have shown a diagnostic, prognostic and predictive value in many types of solid malignancies and recent studies attempted to shed light on their role in ovarian cancer. This review is mainly focused on the clinical value of both CTCs and ctDNA in ovarian cancer and, more specifically, on their potential as diagnostic, prognostic and predictive tumor biomarkers.

Ovarian Tumor Microenvironment Signaling: Convergence on the Rac1 GTPase

The tumor microenvironment for epithelial ovarian cancer is complex and rich in bioactive molecules that modulate cell-cell interactions and stimulate numerous signal transduction cascades. These signals ultimately modulate all aspects of tumor behavior including progression, metastasis and therapeutic response. Many of the signaling pathways converge on the small GTPase Ras-related C3 botulinum toxin substrate (Rac)1. In addition to regulating actin cytoskeleton remodeling necessary for tumor cell adhesion, migration and invasion, Rac1 through its downstream effectors, regulates cancer cell survival, tumor angiogenesis, phenotypic plasticity, quiescence, and resistance to therapeutics. In this review we discuss evidence for Rac1 activation within the ovarian tumor microenvironment, mechanisms of Rac1 dysregulation as they apply to ovarian cancer, and the potential benefits of targeting aberrant Rac1 activity in this disease. The potential for Rac1 contribution to extraperitoneal dissemination of ovarian cancer is addressed.

Personalising Treatment for High-Grade Serous Ovarian Carcinoma

Ovarian cancer is a heterogeneous group of cancers that differ by cell of origin and genomic features. High-grade serous ovarian cancer (HGSOC) is the commonest histiotype and is characterized by extreme genomic complexity and dysregulation of DNA damage repair pathways, particularly homologous recombination deficiency. New insights from molecular profiling into homologous recombination deficiency now offers the credible possibility of personalizing treatment choices for women with HGSOC using poly(ADP-ribose) polymerase inhibitor (PARP) therapy. Although the presence of tumour infiltrating lymphocytes (TILs) in the microenvironment is associated with improved survival in HGSOC, the role of anti-angiogenic and immune checkpoint inhibitor therapy remains unclear. PARP inhibition combined with immunotherapy is an exciting combination strategy for future therapeutic development for women with advanced HGSOC.

Assessment of Circulating Tumor Cells as a Predictive Biomarker of Histology in Women With Suspected Ovarian Cancer

Background

The clinical assessment of circulating tumor cells (CTCs) as a blood-based biomarker is FDA-approved for use in breast, colorectal, and prostate cancers. The objective of this prospective clinical study was to determine whether pretreatment CTCs are a useful diagnostic biomarker in women with complex pelvic masses.

Methods

Whole blood was collected from 49 women with newly diagnosed pelvic masses. The presence of CTCs was compared between women with and without ovarian cancer histopathologic diagnosis after surgery using a Chi-squared test.

Results

CTCs were absent in those with benign disease (0/14), present in 17% (5/29) of patients with a histologic diagnosis of ovarian carcinoma, and present in 80% (4/5) of patients with ovarian metastases from other cancers (P = 0.001). All 5 women with ovarian cancer who had CTCs present presented stage III or IV of the disease (P = 0.13).

Conclusions

CTCs were more prevalent in patients with metastases to the ovary than in primary ovarian carcinomas.

The Clearance of Serum Human Epididymis Protein 4 Following Primary Cytoreductive Surgery for Ovarian Carcinoma

OBJECTIVE

The aim of this study was to examine the clearance of serum human epididymis protein 4 (HE4) in the immediate postoperative period in patients undergoing maximal effort cytoreductive surgery for ovarian carcinoma.

METHODS

The study was performed at a tertiary gynecologic oncology center. The surgery was performed by accredited gynecological oncologists.

RESULTS

Preoperative and serial postoperative venous blood samples at 4, 8, 24, 48, 72, 96, and 120 hours were taken from 10 sequential patients. Pretreatment HE4 is considered elevated at greater than 70 pmol/L. Human epididymis protein 4 was greater than 70 pmol/L in 7 patients, including all patients with high-grade serous carcinoma. Patients with preoperative elevation of serum HE4 and complete cytoreduction cleared more than 80% of serum HE4 in the first 4 hours and more than 88% within 5 days of surgery. One patient with incomplete cytoreduction of high-grade serous carcinoma had 66% clearance at 4 hours and a plateau thereafter.

CONCLUSIONS

Human epididymis protein 4 derived from ovarian carcinoma had a short half-life of less than 4 hours in the circulation when cytoreductive surgery was complete. Sustained low HE4 following surgery could be a useful indicator of the completeness of cytoreduction. Plateau or rise in serum HE4 could suggest persistent disease. Comparison of values on day 1 and day 4 or 5 might have value in assessing the completeness of cytoreduction.

EMT-like circulating tumor cells in ovarian cancer patients are enriched by platinum-based chemotherapy

Background

Assuming that tumor cell dissemination requires a shift to a mesenchymal phenotype, we analyzed the incidence of epithelial-to-mesenchymal-transition (EMT)-like circulating tumor cells (CTCs) in ovarian cancer patients and inquired, how their molecular phenotypes respond to platinum-based chemotherapy and influence outcome.

Results

Before surgery, overall detection rate for epithelial CTCs was 18%. EMT-like CTCs were more frequently observed (30%) and were mutually exclusive to epithelial CTCs in the majority of patients (82%). After chemotherapy, EMT-like CTCs increased up to 52%, accompanied by the “de novo” emergence of PI3Kα+/Twist+ EMT-like CTCs. Before surgery, PI3K+ EMT-like CTCs in combination with epithelial CTCs indicated decreased OS (p = 0.02) and FIGO I-III patients with residual tumor burden after surgery were more likely to be positive for EMT-like CTCs after chemotherapy (p = 0.02). In the latter group, epithelial CTCs alone significantly correlated with decreased PFS and OS (p = 0.02, p = 0.002), supported by an additional inclusion of PI3K+ CTCs (OS, p = 0.001).

Materials and Methods

Blood samples of 91 ovarian cancer patients before surgery and 31 matched samples after adjuvant chemotherapy were evaluated for CTCs with the AdnaTest ovarian cancer and EMT-1, analyzing the epithelial-associated transcripts EpCAM, Muc-1 and CA125 and the EMT-associated transcripts PI3Kα, Akt-2 and Twist.

Conclusions

Platinum-based chemotherapy seems to select for EMT-like CTCs in ovarian cancer patients and provokes a shift towards PI3Kα and Twist expressing CTCs, which may reflect clonal tumor evolution towards therapy resistance. It has to be determined, whether this CTC subgroup may serve as a biomarker to identify patients at high risk.

Improved ovarian cancer EMT-CTC isolation by immunomagnetic targeting of epithelial EpCAM and mesenchymal N-cadherin

Epithelial cell adhesion molecule (EpCAM)-targeted capture remains the most common isolation strategy for circulating tumor cells (CTCs). However, epithelial-to-mesenchymal transition (EMT) leads to decreased epithelial EpCAM expression affecting the optimal CTC capture. In this study, we tested a cohort of ovarian cancer cell lines using flow cytometry to identify N-cadherin as the additional immunomagnetic cell surface target for ovarian cancer cell isolation. Combined immunomagnetic targeting of mesenchymal N-cadherin and epithelial EpCAM enriched CTCs from advanced ovarian cancer patient blood approximately three times more efficiently than targeting of EpCAM alone. We also show that more EMT-phenotype CTCs are captured by including N-cadherin targeting into CTC isolation protocols. However, after N-cadherin-based CTC isolation, in some blood samples of healthy individuals, we also observed the presence of cells expressing markers common to CTCs. Our data show that these "false positives" can be largely distinguished from CTCs as circulating endothelial cells (CECs) by vascular endothelial-cadherin co-staining. CEC counts are highly variable in patients and healthy controls. Our data demonstrate that a combination of EpCAM with N-cadherin-targeted isolation can improve CTC detection and widen the EMT-phenotype spectrum of captured CTCs.

EpCAM-based assays for epithelial tumor cell detection in cerebrospinal fluid

The diagnosis of leptomeningeal metastases (LM) of solid tumors is complicated due to low sensitivities of both magnetic resonance imaging (MRI) and cytology. MRI has a sensitivity of 76% for the diagnosis of LM and cerebrospinal fluid (CSF) cytology has a sensitivity of 44-67% at first lumbar puncture which increases to 84-91% upon second CSF sampling. Epithelial cell adhesion molecule (EpCAM) is expressed by solid tumors of epithelial origin like non-small-cell lung cancer, breast cancer or ovarium cancer. Recently, a CELLSEARCH^® assay and flow cytometry laboratory techniques have been developed to detect circulating tumor cells (CTCs) of epithelial origin in CSF. These laboratory techniques are based on capture antibodies labelled with different fluorescent tags against EpCAM. In this review, we provide an overview of the available laboratory techniques and diagnostic accuracy for tumor cell detection in CSF. The reported sensitivities of the EpCAM-based CTC assays for the diagnosis of LM across the different studies are highly promising and vary between 76 and 100%. An overview of the different EpCAM-based techniques for the enumeration of CTCs in the CSF is given and a comparison is made with CSF cytology for the diagnoses of LM from epithelial tumors.

Targeting epithelial-mesenchymal plasticity in cancer: clinical and preclinical advances in therapy and monitoring

The concept of epithelial-mesenchymal plasticity (EMP), which describes the dynamic flux within the spectrum of phenotypic states that invasive carcinoma cells may reside, is being increasingly recognised for its role in cancer progression and therapy resistance. The myriad of events that are able to induce EMP, as well as the more recently characterised control loops, results in dynamic transitions of cancerous epithelial cells to more mesenchymal-like phenotypes through an epithelial-mesenchymal transition (EMT), as well as the reverse transition from mesenchymal phenotypes to an epithelial one. The significance of EMP, in its ability to drive local invasion, generate cancer stem cells and facilitate metastasis by the dissemination of circulating tumour cells (CTCs), highlights its importance as a targetable programme to combat cancer morbidity and mortality. The focus of this review is to consolidate the existing knowledge on the strategies currently in development to combat cancer progression via inhibition of specific facets of EMP. The prevalence of relapse due to therapy resistance and metastatic propensity that EMP endows should be considered when designing therapy regimes, and such therapies should synergise with existing chemotherapeutics to benefit efficacy. To further improve upon EMP-targeted therapies, it is imperative to devise monitoring strategies to assess the impact of such treatments on EMP-related phenomenon such as CTC burden, chemosensitivity/-resistance and micrometastasis in patients.

Significant prognostic value of circulating tumor cells in esophageal cancer patients: A meta-analysis

Esophageal cancer is the sixth leading cause of cancer death worldwide. Detection of circulating tumor cells (CTCs) is emerging as a novel strategy for predicting cancer patient prognosis. Here we performed a comprehensive literature search to identify relevant articles in EMbase, PubMed, EBSCO, OVID, Cochrane Database, CNKI, WanFangdata and VIPdata. Meta-analysis was conducted using Stata12.0 software, according to the inclusion and exclusion criteria, extracted data and assessment methodology. Thirteen eligible literature studies were included with a total of 979 esophageal squamous cell carcinoma patients, including 424 CTC-positive and 684 CTC-negative cases. Meta-analysis showed that the presence of CTCs was associated with both worse progression-free/disease-free survival [hazard ration (HR) = 2.32, 95% confidence interval (CI) = 1.57 - 3.43, p < 0.001] and poorer overall survival [HR = 2.64, 95% CI = 1.69 - 4.14, p < 0.001]. Further subgroup analyses demonstrated that CTC-positive patients also showed worse progression-free/disease-free survival and poorer overall survival in different subsets. In summary, our meta-analysis provides strong evidence that detection of CTCs in the peripheral blood is an independent prognostic indicator of poor outcome for esophageal squamous cell carcinoma patients.

Circulating and disseminated tumor cells in pancreatic cancer and their role in patient prognosis: a systematic review and meta-analysis

Background

Disseminated tumor cells (DTCs) and circulating tumor cells (CTCs) have been postulated to seed metastases and contribute to poorer patient outcomes in many types of solid cancer. To date, no systematic reviews have examined the role of both DTCs and CTCs in pancreatic cancer. We aimed to determine the prognostic value of DTCs/CTCs in pancreatic cancer using a systematic review and meta-analysis.

Materials and Methods

A comprehensive literature search identified studies examining DTCs and CTCs in the bone marrow and blood of pancreatic cancer patients at diagnosis with follow-up to determine disease-free/progression-free survival (DFS/PFS) and overall survival (OS). Statistical analyses were performed to determine the hazard ratio (HR) of DTCs/CTCs on DFS/PFS and OS.

Results

The literature search identified 16 articles meeting the inclusion criteria. The meta-analysis demonstrated statistically significant HR differences in DFS/PFS (HR = 1.93, 95% CI 1.19–3.11, P = 0.007) and OS (HR = 1.84, 95% CI 1.37–2.45, P =< 0.0001), indicating patients with detectable DTCs/CTCs at diagnosis have worse prognoses. Subgroup analyses suggested CTCs in the peripheral blood (HR =2.03) were more indicative of poor OS prognosis than DTCs in the bone marrow (HR = 1.91), although the difference between these was not statistically significant. Positivity of the CellSearch detection method for DTC/CTC had the highest correlation with decreased OS (HR = 2.79) while immunodetection (HR = 1.91) and RT-PCR (HR = 1.25) were less effective in determining prognosis.

Conclusion

The detection of DTCs/CTCs at diagnosis is associated with poorer DFS/PFS and OS in pancreatic cancer.

Prediction of therapy response in ovarian cancer: Where are we now?

Therapy resistance is a major challenge in the management of ovarian cancer (OC). Advances in detection and new technology validation have led to the emergence of biomarkers that can predict responses to available therapies. It is important to identify predictive biomarkers to select resistant and sensitive patients in order to reduce important toxicities, to reduce costs and to increase survival. The discovery of predictive and prognostic biomarkers for monitoring therapy is a developing field and provides promising perspectives in the era of personalized medicine. This review article will discuss the biology of OC with a focus on targetable pathways; current therapies; mechanisms of resistance; predictive biomarkers for chemotherapy, antiangiogenic and DNA-targeted therapies, and optimal cytoreductive surgery; and the emergence of liquid biopsy using recent studies from the Medline database and ClinicalTrials.gov.

Predictive value of circulating tumor cells (CTCs) captured by microfluidic device in patients with epithelial ovarian cancer

OBJECTIVE

To test an electrically conductive chip, incorporating a nanoroughened microfluidic platform for the capture of circulating tumor cells (CTCs), and assess its clinical merit in instances of epithelial ovarian cancer (EOC).

METHODS

A total of 54 patients with EOC recruited between August 2014 and May 2015 were enrolled in this prospective study. CTCs in peripheral blood were detected in advance of primary tumor resection and before initiating adjuvant chemotherapy for recurrent disease. We identified CTCs as EpCAM-positive and DAPI-positive, and CD45-negative feature.

RESULTS

Twenty-four patients with primary disease and 30 patients with recurrences were included in the study. CTCs were detected in 98.1% (53/54). In newly diagnosed patients, median counts of single CTCs and CTC clusters were 4 (0-13) and 1(0-14), respectively. In those with recurrences, median counts were 3 (1-9) and 1(0-24), respectively. Such counts did not differ significantly by tumor stage or by serum CA125 level; but progression-free survival declined at a cutpoint of ≥3 CTCs, and CTC-cluster positivity correlated with platinum resistance. Isolated CTCs (successfully cultured ex vivo in two patients) showed greater sensitivity to anticancer drugs and proliferated more rapidly than did established cell lines.

CONCLUSION

Proof-of-concept was provided for an electrically conductive and nanoroughened microfluidic platform-based chip designed to capture CTCs in patients with EOC. A larger patient sampling and longer duration of follow-up are needed to determine its suitability for clinical use.

Review article: Novel technologies in the treatment and monitoring of advanced and relapsed epithelial ovarian cancer

Epithelial Ovarian cancer (EOC) is the fifth most common cause of cancer death in females in the UK. It has long been recognized to be a set of heterogeneous diseases, with high grade serous being the most common subtype. The majority of patients with EOC present at an advanced stage (FIGO III-IV), and have the largest risk for disease recurrence from which a high percentage will develop resistance to chemotherapy. Despite continual advances in diagnostics, imaging, surgery and treatment of EOC, there has been little variation in the survival rates for patients with EOC. In this review we will introduce novel bioengineering advances in modelling the lymphatic system and real-time tissue monitoring to improve the clinical and therapeutic outcome for patients with EOC. We discuss the advent of the non-invasive "liquid biopsy" in the surveillance of patients undergoing treatment and follow-up. Finally, we present new bioengineering advances for palliative care of patients to lessen symptoms of patients with ascites and improve quality of life.

Circulating tumor cells and circulating tumor DNA: What surgical oncologists need to know?

As a result of recent progress in detection techniques, circulating tumor DNA (ctDNA) and circulating tumor cells (CTC) can now be accurately detected in the blood of most cancer patients. While these new biomarkers can provide a better understanding of key biological mechanisms underlying cancer growth and dissemination, they also open up a wide range of possible clinical applications in medical oncology, radiation oncology and surgical oncology. In this review, we summarize the results obtained with ctDNA and CTC together with their potential future clinical applications in the field of surgical oncology, with particular focus on the perioperative setting of various types of cancer. These applications include, but are not limited to, cancer screening, early diagnosis, prognostic assessment, evaluation and management of preoperative systemic or local therapies, post-surgical detection of minimal residual disease and early detection of cancer relapse.

Detecting Tumor Metastases: The Road to Therapy Starts Here

Metastasis is the complex process by which primary tumor cells migrate and establish secondary tumors in an adjacent or distant location in the body. Early detection of metastatic disease and effective therapeutic options for targeting these detected metastases remain impediments to effectively treating patients with advanced cancers. If metastatic lesions are identified early, patients might maximally benefit from effective early therapeutic interventions. Further, monitoring patients whose primary tumors are effectively treated for potential metastatic disease onset is also highly valuable. Finally, patients with metastatic disease can be monitored for efficacy of specific therapeutic interventions through effective metastatic detection techniques. Thus, being able to detect and visualize metastatic lesions is key and provides potential to greatly improve overall patient outcomes. In order to achieve these objectives, researchers have endeavored to mechanistically define the steps involved in the metastatic process as well as ways to effectively detect metastatic progression. We presently overview various preclinical and clinical in vitro and in vivo assays developed to more efficiently detect tumor metastases, which provides the foundation for developing more effective therapies for this invariably fatal component of the cancerous process.

Gene expression profiling of single circulating tumor cells in ovarian cancer - Establishment of a multi-marker gene panel

The presence of circulating tumor cells (CTCs) in the blood of ovarian cancer patients was shown to correlate with decreased overall survival, whereby CTCs with epithelial-mesenchymal-transition (EMT) or stem-like traits are supposed to be involved in metastatic progression and recurrence. Thus, investigating the transcriptional profiles of CTCs might help to identify therapy resistant tumor cells and to overcome treatment failure. For this purpose, we established a multi-marker panel for the molecular characterization of single CTCs, detecting epithelial (EpCAM, Muc-1, CK5/7), EMT (N-cadherin, Vimentin, Snai1/2, CD117, CD146, CD49f) and stem cell (CD44, ALDH1A1, Nanog, SOX2, Notch1/4, Oct4, Lin28) associated transcripts. First primer specificity and PCR-performance of the multiplex-RT-PCRs were successfully validated on genomic DNA and cDNA isolated from OvCar3 cells. The assay sensitivity of the epithelial panel was evaluated by adding defined numbers of tumor cells into the blood of healthy donors and performing a subsequent immunomagnetic tumor cell enrichment (AdnaTest OvarianCancerSelect), resulting in a 100% concordance for the epithelial markers EpCAM and Muc-1 to the AdnaTest OvarianCancerDetect. Additionally, by processing blood from ovarian cancer patients, high assay sensitivity could be verified. In blood of healthy donors no signals for epithelial markers were detected, for EMT and stem cell markers, however, signals were obtained mainly originating from leukocytes which calls for single cell analysis. To that aim by using the ovarian cancer cell line OvCar3, we successfully established a workflow enabling the characterization of single CTCs. It consists of a density gradient-dependent enrichment for nucleated cells, a depletion of CD45-positive cells of hematopoietic origin followed by immunofluorescent labeling of CTCs by EpCAM and Muc-1. Single CTCs are then isolated by micromanipulation and processed for panel gene expression profiling. Finally, fifteen single CTCs from three ovarian cancer patients were analyzed and found to be positive for stem cell (CD44, ALDH1A1, Nanog, Oct4) and EMT markers (N-cadherin, Vimentin, Snai2, CD117, CD146). Albeit, inter-cellular and intra/inter-patient heterogeneity and co-expression of epithelial, mesenchymal and stem cell transcripts on the same CTC was observed. We have established a robust workflow to perform sensitive single cell panel gene expression analysis without the need of pre-amplification steps. Our data point towards a heterogeneous expression of stem cell and EMT associated transcripts in ovarian cancer CTCs.

Circulating tumor cells as trigger to hematogenous spreads and potential biomarkers to predict the prognosis in ovarian cancer

Despite several improvements in the surgical field and in the systemic treatment, ovarian cancer (OC) is still characterized by high recurrence rates and consequently poor survival. In OC, there is still a great lack of knowledge with regard to cancer behavior and mechanisms of recurrence, progression, and drug resistance. The OC metastatization process mostly occurs via intracoelomatic spread. Recent evidences show that tumor cells generate a favorable microenvironment consisting in T regulatory cells, T infiltrating lymphocytes, and cytokines which are able to establish an "immuno-tolerance mileau" in which a tumor cell can become a resistant clone. When the disease responds to treatment, immunoediting processes and cancer progression have been stopped. A similar inhibition of the immunosuppressive microenvironment has been observed after optimal cytoreductive surgery as well. In this scenario, the early identification of circulating tumor cells could represent a precocious signal of loss of the immune balance that precedes cancer immunoediting and relapse. Supporting this hypothesis, circulating tumor cells have been demonstrated to be a prognostic factor in several solid tumors such as colorectal, pancreatic, gastric, breast, and genitourinary cancer. In OC, the role of circulating tumor cells is still to be defined. However, as opposed to healthy women, circulating tumor cells have been demonstrated in peripheral blood of OC patients, opening a new research field in OC diagnosis, treatment monitoring, and follow-up.