A Multi-Center Clinical Study to Harvest and Characterize Circulating Tumor Cells from Patients with Metastatic Breast Cancer Using the Parsortix® PC1 System

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.

Comprehensive liquid biopsy analysis for monitoring NSCLC patients under second-line osimertinib treatment

Background

The heterogeneous and complex genetic landscape of NSCLC impacts the clinical outcomes of patients who will eventually develop resistance to osimertinib. Liquid biopsy (LB) analysis as a minimally invasive approach is a key step to efficiently identify resistance mechanisms and adjust to proper subsequent treatments.

Materials and methods

In the present study, we combined plasma-cfDNA and CTC analysis from 30 NSCLC patients in samples collected before treatment and at the progression of disease (PD). We detected molecular alterations at the DNA mutation (EGFR, PIK3CA, KRAS G12C, BRAF V600E), DNA methylation (RASSF1A, BRMS1, FOXA1, SLFN1, SHISA3, RARβ,, WIF-1, RASSF10 and APC), gene expression (CK-19, CK-18, CK-8, AXL, TWIST-1, PD-L1, PIM-1, Vimentin, ALDH-1, and B2M) and chromosomal level (HER2 and MET amplification) as possible resistance mechanisms and druggable targets. We also studied the expression of PD-L1 in single CTCs using immunofluorescence.

Results

In some cases, T790M resistance EGFR mutation was detected at baseline in CTCs but not in the corresponding plasma cfDNA. PIK3CA mutations were detected only in plasma-cfDNA but not in corresponding CTCs. KRAS G12C and BRAF V600E mutations were not detected in the samples analyzed. MET amplification was detected in the CTCs of two patients before treatment whereas HER2 amplification was detected in the CTCs of three patients at baseline and in one patient at PD. DNA methylation analysis revealed low concordance between CTCs and cfDNA, indicating the complementary information obtained through parallel LB analysis. Results from gene expression analysis indicated high rates of vimentin-positive CTCs detected at all time points during osimertinib. Moreover, there was an increased number of NSCLC patients at PD harboring CTCs positive in PD-L1. AXL and PIM-1 expression detected in CTCs during treatment suggesting new possible therapeutic strategies.

Discussion

Our results reveal that comprehensive liquid biopsy analysis can efficiently represent the heterogeneous molecular landscape and provide prominent information on subsequent treatments for NSCLC patients at PD since druggable molecular alterations were detected in CTCs.

Identification of circulating tumor cells captured by the FDA-cleared Parsortix® PC1 system from the peripheral blood of metastatic breast cancer patients using immunofluorescence and cytopathological evaluations

Circulating Tumor Cells (CTCs) may serve as a non-invasive source of tumor material to investigate an individual's disease in real-time. The Parsortix® PC1 System, the first FDA-cleared medical device for the capture and harvest of CTCs from peripheral blood of metastatic breast cancer (MBC) patients for use in subsequent user-validated downstream analyses, enables the epitope-independent capture of CTCs with diverse phenotypes based on cell size and deformability. The aim of this study was to determine the proportion of MBC patients and self-declared female healthy volunteers (HVs) that had CTCs identified using immunofluorescence (IF) or Wright-Giemsa (WG) staining. Peripheral blood from 76 HVs and 76 MBC patients was processed on Parsortix® PC1 Systems. Harvested cells were cytospun onto a charged slide and immunofluorescently stained for identification of CTCs expressing epithelial markers. The IF slides were subsequently WG-stained and analyzed for CTC identification based on morphological features of malignant cells. All testing was performed by operators blinded to the clinical status of each subject. CTCs were identified on the IF slides in 45.3% (≥ 1) / 24.0% (≥ 5) of the MBC patients (range = 0 - 125, mean = 7) and in 6.9% (≥ 1) / 2.8% (≥ 5) of the HVs (range = 0 - 28, mean = 1). Among the MBC patients with ≥ 1 CTC, 70.6% had only CK + /EpCAM- CTCs, with none having EpCAM + /CK- CTCs. CTC clusters were identified in 56.0% of the CTC-positive patients. On the WG-stained slides, CTCs were identified in 42.9% (≥ 1) / 21.4% (≥ 5) of the MBC patients (range = 0 - 41, mean = 4) and 4.3% (≥ 1) / 2.9% (≥ 5) of the HVs (range = 0 - 14, mean = 0). This study demonstrated the ability of the Parsortix® PC1 System to capture and harvest CTCs from a significantly larger proportion of MBC patients compared to HVs when coupled with both IF and WG cytomorphological assessment. The presence of epithelial cells in subjects without diagnosed disease has been previously described, with their significance being unclear. Interestingly, a high proportion of the identified CTCs did not express EpCAM, highlighting the limitations of using EpCAM-based approaches.

A comparative study of circulating tumor cell isolation and enumeration technologies in lung cancer

Circulating tumor cells (CTCs) have potential as diagnostic, prognostic, and predictive biomarkers in solid tumors. Despite Food and Drug Administration (FDA) approval of CTC devices in various cancers, the rarity and heterogeneity of CTCs in lung cancer make them technically challenging to isolate and analyze, hindering their clinical integration. Establishing a consensus through comparative analysis of different CTC systems is warranted. This study aimed to evaluate seven different CTC enrichment methods across five technologies using a standardized spike-in protocol: the CellMag™ (EpCAM-dependent enrichment), EasySep™ and RosetteSep™ (blood cell depletion), and the Parsortix® PR1 and the new design Parsortix® Prototype (PP) (size- and deformability-based enrichment). The Parsortix® systems were also evaluated for any differences in recovery rates between cell harvest versus in-cassette staining. Healthy donor blood (5 mL) was spiked with 100 fluorescently labeled EpCAMhigh H1975 cells, processed through each system, and the isolation efficiency was calculated. The CellMag™ had the highest recovery rate (70 ± 14%), followed by Parsortix® PR1 in-cassette staining, while the EasySep™ had the lowest recovery (18 ± 8%). Additional spike-in experiments were performed with EpCAMmoderate A549 and EpCAMlow H1299 cells using the CellMag™ and Parsortix® PR1 in-cassette staining. The recovery rate of CellMag™ significantly reduced to 35 ± 14% with A549 cells and 1 ± 1% with H1299 cells. However, the Parsortix® PR1 in-cassette staining showed cell phenotype-independent and consistent recovery rates among all lung cancer cell lines: H1975 (49 ± 2%), A549 (47 ± 10%), and H1299 (52 ± 10%). Furthermore, we demonstrated that the Parsortix® PR1 in-cassette staining method is capable of isolating heterogeneous single CTCs and cell clusters from patient samples. The Parsortix® PR1 in-cassette staining, capable of isolating different phenotypes of CTCs as either single cells or cell clusters with consistent recovery rates, is considered optimal for CTC enrichment for lung cancer, albeit needing further optimization and validation.

Combined microfluidic enrichment and staining workflow for single-cell analysis of circulating tumor cells in metastatic prostate cancer patients

Circulating tumor cells (CTCs) are precursors of cancer in the blood and provide an attractive source for dynamic monitoring of disease progression and tumor heterogeneity. However, the scarcity of CTCs in the bloodstream has limited their use in clinical practice. In this study, we present a workflow for easy detection of CTCs by cytokeratin staining using the FDA-cleared Parsortix device for size-based microfluidic enrichment. To minimize sample handling, the isolated cells are stained inside the separation cassette and harvested for subsequent single cell isolation and whole genome copy-number analysis. We validated the workflow on a panel of four prostate cancer cell lines spiked into healthy donor blood collected in CellRescue or EDTA tubes, resulting in mean recoveries of 42% (16-69%). Furthermore, we evaluated the clinical utility in a cohort of 12 metastatic prostate cancer patients and found CTCs in 67% of patients ranging from 0 to 1172 CTCs in 10 mL blood. Additionally, we isolated single patient-derived CTCs and identified genomic aberrations associated with treatment response and clinical outcome. Thus, this workflow provides a readily scalable strategy for analysis of single CTCs, applicable for use in monitoring studies to identify genomic variations important for guiding clinical therapy decision.

The correlation study between TOP2A gene expression in circulating tumor cells and chemotherapeutic drug resistance of patients with breast cancer

BACKGROUND

Patients with breast cancer (BC) at advanced stages have poor outcomes because of high rate of recurrence and metastasis. Biomarkers for predicting prognosis remain to be explored. This study aimed to evaluate the relationships between circulating tumor cells (CTCs) and outcomes of BC patients.

PATIENTS AND METHODS

A total of 50 female were enrolled in this study. Their diagnoses were determined by clinical characteristics, image data, and clinical pathology. CTC subtypes and TOP2A gene expression on CTCs were detected by CanPatrol™ technology and triple color in situ RNA hybridization (RNA-ISH), which divided into epithelial CTCs (eCTCs), mesenchymal CTCs (MCTCs), and hybrid CTCs (HCTCs) based on their surface markers. Hormone receptor, including estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) expression, was measured by immunohistochemistry (IHC) method before treatment. The risk factors for predicting recurrence and metastasis were calculated by COX risk regression model. The progression-free survival (PFS) of patients was determined using Kaplan-Meier survival curve.

RESULTS

The patients with a large tumor size (≥ 3 cm) and advanced tumor node metastasis (TNM) stages had high total CTCs (TCTCs) (P < 0.05). These patients also had high TOP2A expression level. COX risk regression analysis indicated that TOP2A expression levels in TCTCs, ER + , HER-2 + , and TNM stages were critical risk factors for recurrence and metastasis of patients (P < 0.05). The PFS of patients with ≥ 5 TCTCs, ≥ 3 HCTCs, and positive TOP2A expression in ≥ 3 TCTCs was significantly longer than that in patient with < 5 TCTCs, < 3 HCTCs, and TOP2A expression in < 3 TCTCs (P < 0.05). In contrast, the PFS of patients with positive hormone receptors (ER + , PR + , HER-2 +) also was dramatically lived longer than that in patients with negative hormone receptor expression.

CONCLUSIONS

High TCTC, HCTCs, and positive TOP2A gene expression on CTCs were critical biomarkers for predicting outcomes of BC patients. Positive hormone receptor expression in BC patients has significant favor PFS.

Circulating tumor cells et al.: towards a comprehensive liquid biopsy approach in breast cancer

Liquid biopsy has emerged as a crucial tool in managing breast cancer (BC) patients, offering a minimally invasive approach to detect circulating tumor biomarkers. Until recently, the majority of the studies in BC focused on evaluating a single liquid biopsy analyte, primarily circulating tumor DNA and circulating tumor cells (CTCs). Despite the proven prognostic and predictive value of CTCs, their low abundance when detected using enrichment methods, especially in the early stages, poses a significant challenge. It is becoming evident that combining diverse circulating biomarkers, each representing different facets of tumor biology, has the potential to enhance the management of patients with BC. This article emphasizes the importance of considering these biomarkers as complementary/synergistic rather than competitive, recognizing their ability to contribute to a comprehensive disease profile. The review provides an overview of the clinical significance of simultaneously analyzing CTCs and other biomarkers, including cell-free circulating DNA, extracellular vesicles, non-canonical CTCs, cell-free RNAs, and non-malignant cells. Such a comprehensive liquid biopsy approach holds promise not only in BC but also in other cancer types, offering opportunities for early detection, prognostication, and therapy monitoring. However, addressing associated challenges, such as refining detection methods and establishing standardized protocols, is crucial for realizing the full potential of liquid biopsy in transforming our understanding and approach to BC. As the field evolves, collaborative efforts will be instrumental in unlocking the revolutionary impact of liquid biopsy in BC research and management.

Precision Oncology in Breast Cancer Surgery

Outcomes for patients with breast cancer have improved over time due to increased screening and the availability of more effective therapies. It is important to recognize that breast cancer is a heterogeneous disease that requires treatment based on molecular characteristics. Early endpoints such as pathologic complete response correlate with event-free survival, allowing the opportunity to consider de-escalation of certain cancer treatments to avoid overtreatment. This article discusses clinical trials of tailoring treatment (eg, I-SPY2) and screening (eg, WISDOM) to individual patients based on their unique risk features.

c-MET-positive circulating tumor cells and cell-free DNA as independent prognostic factors in hormone receptor-positive/HER2-negative metastatic breast cancer

BACKGROUND

Endocrine therapy resistance in hormone receptor-positive/HER2-negative (HR+/HER2-) breast cancer (BC) is a significant clinical challenge that poses several unmet needs in the management of the disease. This study aimed to investigate the prognostic value of c-MET-positive circulating tumor cells (cMET+ CTCs), ESR1/PIK3CA mutations, and cell-free DNA (cfDNA) concentrations in patients with hormone receptor-positive (HR+) metastatic breast cancer (mBC).

METHODS

Ninety-seven patients with HR+ mBC were prospectively enrolled during standard treatment at Samsung Medical Center. CTCs were isolated from blood using GenoCTC® and EpCAM or c-MET CTC isolation kits. PIK3CA and ESR1 hotspot mutations were analyzed using droplet digital PCR. CfDNA concentrations were calculated using internal control copies from the ESR1 mutation test. Immunocytochemistry was performed to compare c-MET overexpression between primary and metastatic sites.

RESULTS

The proportion of c-MET overexpression was significantly higher in metastatic sites than in primary sites (p = 0.00002). Survival analysis showed that c-MET+ CTC, cfDNA concentration, and ESR1 mutations were significantly associated with poor prognosis (p = 0.0026, 0.0021, and 0.0064, respectively) in HR+/HER2- mBC. By contrast, EpCAM-positive CTC (EpCAM+ CTC) and PIK3CA mutations were not associated with progression-free survival (PFS) in HR+/HER2- mBC. Multivariate analyses revealed that c-MET+ CTCs and cfDNA concentration were independent predictors of PFS in HR+/HER2- mBC.

CONCLUSIONS

Monitoring c-MET+ CTC, rather than assessing c-MET expression in the primary BC site, could provide valuable information for predicting disease progression, as c-MET expression can change during treatment. The c-MET+ CTC count and cfDNA concentration could provide complementary information on disease progression in HR+ /HER2- mBC, highlighting the importance of integrated liquid biopsy.

Molecular Profiling of Circulating Tumour Cells and Circulating Tumour DNA: Complementary Insights from a Single Blood Sample Utilising the Parsortix® System

The study of molecular drivers of cancer is an area of rapid growth and has led to the development of targeted treatments, significantly improving patient outcomes in many cancer types. The identification of actionable mutations informing targeted treatment strategies are now considered essential to the management of cancer. Traditionally, this information has been obtained through biomarker assessment of a tissue biopsy which is costly and can be associated with clinical complications and adverse events. In the last decade, blood-based liquid biopsy has emerged as a minimally invasive, fast, and cost-effective alternative, which is better suited to the requirement for longitudinal monitoring. Liquid biopsies allow for the concurrent study of multiple analytes, such as circulating tumour cells (CTCs) and circulating tumour DNA (ctDNA), from a single blood sample. Although ctDNA assays are commercially more advanced, there is an increasing awareness of the clinical significance of the transcriptome and proteome which can be analysed using CTCs. Herein, we review the literature in which the microfluidic, label-free Parsortix® system is utilised for CTC capture, harvest and analysis, alongside the analysis of ctDNA from a single blood sample. This detailed summary of the literature demonstrates how these two analytes can provide complementary disease information.

Clinical application of circulating tumor cells

This narrative review aims to provide a comprehensive overview of the current state of circulating tumor cell (CTC) analysis and its clinical significance in patients with epithelial cancers. The review explores the advancements in CTC detection methods, their clinical applications, and the challenges that lie ahead. By examining the important research findings in this field, this review offers the reader a solid foundation to understand the evolving landscape of CTC analysis and its potential implications for clinical practice. The comprehensive analysis of CTCs provides valuable insights into tumor biology, treatment response, minimal residual disease detection, and prognostic evaluation. Furthermore, the review highlights the potential of CTCs as a non-invasive biomarker for personalized medicine and the monitoring of treatment efficacy. Despite the progress made in CTC research, several challenges such as standardization, validation, and integration into routine clinical practice remain. The review concludes by discussing future directions and the potential impact of CTC analysis on improving patient outcomes and guiding therapeutic decision-making in epithelial cancers.

Pre-analytical conditions and implementation of quality control steps in liquid biopsy analysis

Over the last decade, great advancements have been made in the field of liquid biopsy through extensive research and the development of new technologies that facilitate the use of liquid biopsy for cancer patients. This is shown by the numerous liquid biopsy tests that gained clearance by the US Food and Drug Administration (FDA) in recent years. Liquid biopsy has significantly altered cancer treatment by providing clinicians with powerful and immediate information about therapeutic decisions. However, the clinical integration of liquid biopsy is still challenging and there are many critical factors to consider prior to its implementation into routine clinical practice. Lack of standardization due to technical challenges and the definition of the clinical utility of specific assays further complicates the establishment of Standard Operating Procedures (SOPs) in liquid biopsy. Harmonization of laboratories to established guidelines is of major importance to overcome inter-lab variabilities observed. Quality control assessment in diagnostic laboratories that offer liquid biopsy testing will ensure that clinicians can base their therapeutic decisions on robust results. The regular participation of laboratories in external quality assessment schemes for liquid biopsy testing aims to promptly pinpoint deficiencies and efficiently educate laboratories to improve their quality of services. Accreditation of liquid biopsy diagnostic laboratories based on the ISO15189 standard in Europe or by CLIA/CAP accreditation procedures in the US is the best way to achieve the adaptation of liquid biopsy into the clinical setting by assuring reliable results for the clinicians and their cancer patients. Nowadays, various organizations from academia, industry, and regulatory agencies collaborate to set a framework that will include all procedures from the pre-analytical phase and the analytical process to the final interpretation of results. In this review, we underline several challenges in the analysis of circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs) concerning standardization of protocols, quality control assessment, harmonization of laboratories, and compliance to specific guidelines that need to be thoroughly considered before liquid biopsy enters the clinic.

A New Era of Integration between Multiomics and Spatio-Temporal Analysis for the Translation of EMT towards Clinical Applications in Cancer

Epithelial-mesenchymal transition (EMT) is crucial to metastasis by increasing cancer cell migration and invasion. At the cellular level, EMT-related morphological and functional changes are well established. At the molecular level, critical signaling pathways able to drive EMT have been described. Yet, the translation of EMT into efficient diagnostic methods and anti-metastatic therapies is still missing. This highlights a gap in our understanding of the precise mechanisms governing EMT. Here, we discuss evidence suggesting that overcoming this limitation requires the integration of multiple omics, a hitherto neglected strategy in the EMT field. More specifically, this work summarizes results that were independently obtained through epigenomics/transcriptomics while comprehensively reviewing the achievements of proteomics in cancer research. Additionally, we prospect gains to be obtained by applying spatio-temporal multiomics in the investigation of EMT-driven metastasis. Along with the development of more sensitive technologies, the integration of currently available omics, and a look at dynamic alterations that regulate EMT at the subcellular level will lead to a deeper understanding of this process. Further, considering the significance of EMT to cancer progression, this integrative strategy may enable the development of new and improved biomarkers and therapeutics capable of increasing the survival and quality of life of cancer patients.

Evolving insights in blood-based liquid biopsies for prostate cancer interrogation

During the last decade, blood sampling of cancer patients aimed at analyzing the presence of cells, membrane-bound vesicles, or molecules released by primary tumors or metastatic growths emerged as an alternative to traditional tissue biopsies. The advent of this minimally invasive approach, known as blood-based liquid biopsy, began to play a pivotal role in the management of diverse cancers, establishing itself as a vital component of precision medicine. Here, we discuss three blood-based liquid biopsies, namely circulating tumor cells (CTCs), circulating tumor DNA (ctDNA) and tumor-derived exosomes, as they relate to prostate cancer (PCa) management. The advances achieved in the molecular characterization of these types of liquid biopsies and their potential to predict recurrence, improve responses to certain treatments, and evaluate prognosis, in PCa patients, are highlighted herein. While there is currently full clinical validation for only one CTC-based and one ctDNA-based liquid biopsy for patients with metastatic castration-resistant PCa, the adoption of additional methods is anticipated as they undergo standardization and achieve analytical and clinical validation. Advantages and disadvantages of different blood-based liquid biopsy approaches in the context of PCa are outlined herein, while also considering potential synergies through combinatory strategies.

Updates on Breast Cancer

This collection of 18 articles, comprising 12 original studies, 1 systematic review, and 5 reviews, is a collaborative effort by distinguished experts in breast cancer research, and it has been edited by Dr [...].

Latest advances in clinical studies of circulating tumor cells in early and metastatic breast cancer

Circulating tumor cells (CTCs) have emerged as a promising biomarker in breast cancer, offering insights into disease progression and treatment response. While CTCs have demonstrated prognostic relevance in early breast cancer, more validation is required to establish optimal cut-off points. In metastatic breast cancer, the detection of CTCs using the Food and Drug Administration-approved CellSearch® system is a strong independent prognostic factor. However, mesenchymal CTCs and the Parsortix® PC1 system show promise as alternative detection methods. This chapter offers a comprehensive review of clinical studies on CTCs in breast cancer, emphasizing their prognostic and predictive value in different stages of the disease and provides insights into potential future directions in CTC research.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Detection and Molecular Characterization of Circulating Tumour Cells: Challenges for the Clinical Setting

Over the last decade, liquid biopsy has gained much attention as a powerful tool in personalized medicine since it enables monitoring cancer evolution and follow-up of cancer patients in real time. Through minimally invasive procedures, liquid biopsy provides important information through the analysis of circulating tumour cells (CTCs) and circulating tumour-derived material, such as circulating tumour DNA (ctDNA), circulating miRNAs (cfmiRNAs) and extracellular vehicles (EVs). CTC analysis has already had an important impact on the prognosis, detection of minimal residual disease (MRD), treatment selection and monitoring of cancer patients. Numerous clinical trials nowadays include a liquid biopsy arm. CTC analysis is now an exponentially expanding field in almost all types of solid cancers. Functional studies, mainly based on CTC-derived cell-lines and CTC-derived explants (CDx), provide important insights into the metastatic process. The purpose of this review is to summarize the latest findings on the clinical significance of CTCs for the management of cancer patients, covering the last four years. This review focuses on providing a comprehensive overview of CTC analysis in breast, prostate and non-small-cell lung cancer. The unique potential of CTC single-cell analysis for understanding metastasis biology, and the importance of quality control and standardization of methodologies used in this field, is also discussed.

Extracellular Vesicles as Biomarkers in Head and Neck Squamous Cell Carcinoma: From Diagnosis to Disease-Free Survival

Head and neck squamous cell carcinomas (HNSCCs) arising from different anatomical sites present with different incidences and characteristics, which requires a personalized treatment strategy. Despite the extensive research that has conducted on this malignancy, HNSCC still has a poor overall survival rate. Many attempts have been made to improve the outcomes, but one of the bottlenecks is thought to be the lack of an effective biomarker with high sensitivity and specificity. Extracellular vesicles (EVs) are secreted by various cells and participate in a great number of intercellular communications. Based on liquid biopsy, EV detection in several biofluids, such as blood, saliva, and urine, has been applied to identify the existence and progression of a variety of cancers. In HNSCC, tumor-derived EVs exhibit many functionalities by transporting diverse cargoes, which highlights their importance in tumor screening, the determination of multidisciplinary therapy, prediction of prognosis, and evaluation of therapeutic effects. This review illustrates the classification and formation of EV subtypes, the cargoes conveyed by these vesicles, and their respective functions in HNSCC cancer biology, and discloses their potential as biomarkers during the whole process of tumor diagnosis, treatment, and follow-up.

Circulating Tumor Cells in Cancer Diagnostics and Prognostics by Single-Molecule and Single-Cell Characterization

Circulating tumor cells (CTCs) represent an interesting source of biomarkers for diagnosis, prognosis, and the prediction of cancer recurrence, yet while they are extensively studied in oncobiology research, their diagnostic utility has not yet been demonstrated and validated. Their scarcity in human biological fluids impedes the identification of dangerous CTC subpopulations that may promote metastatic dissemination. In this Perspective, we discuss promising techniques that could be used for the identification of these metastatic cells. We first describe methods for isolating patient-derived CTCs and then the use of 3D biomimetic matrixes in their amplification and analysis, followed by methods for further CTC analyses at the single-cell and single-molecule levels. Finally, we discuss how the elucidation of mechanical and morphological properties using techniques such as atomic force microscopy and molecular biomarker identification using nanopore-based detection could be combined in the future to provide patients and their healthcare providers with a more accurate diagnosis.

Comparison of RNA Marker Panels for Circulating Tumor Cells and Evaluation of Their Prognostic Relevance in Breast Cancer

Liquid biopsy is a promising tool for therapy monitoring of cancer patients, but a need for further research in this field exists in order to improve sensitivity, specificity, standardization and minimize costs. In our present study, we evaluated two panels of transcripts related with the presence of circulating tumor cells (CTCs) (Panel 1: CK19, EpCAM, SCGB2A2 and Panel 2: EMP2, SLC6A8, HJURP, MAL2, PPIC and CCNE2) in two cohorts of breast cancer patients (metastatic and early). A blood cell fraction possibly containing CTCs was isolated with density gradient centrifugation, followed by RNA isolation and qPCR using TaqMan^® or RT-qPCR using hybridization probes. The positivity rates of the investigated panels were similar, albeit higher in metastatic (69.4% Panel 1, 75.0% Panel 2; total 86.1%) compared to early (18.9% Panel 1, 23.3% Panel 2; total 31.1%) breast cancer patients. CK19, SCGB2A2, EMP2, HJURP, MAL2, and CCNE2 individually correlated with shorter overall survival in the metastatic patient cohort. The findings highlight the additional value of Panel 2 markers, which are in contrast to CK19 and EpCAM not solely linked to an epithelial phenotype.

Analytical performance of the FDA-cleared Parsortix® PC1 system

Introduction

The Parsortix® PC1 system, Food and Drug Administration (FDA) cleared for use in metastatic breast cancer (MBC) patients, is an epitope-independent microfluidic device for the capture and harvest of circulating tumor cells from whole blood based on cell size and deformability. This report details the analytical characterization of linearity, detection limit, precision, and reproducibility for this device.

Methods

System performance was determined using K2-EDTA blood samples collected from self-declared healthy female volunteers (HVs) and MBC patients spiked with prelabeled cultured breast cancer cell lines (SKBR3, MCF7, or Hs578T). Samples were processed on Parsortix® PC1 systems and captured cells were harvested and enumerated.

Results

The system captured and harvested live SKBR3, MCF7, and Hs578T cells and fixed SKBR3 cells linearly between 2 and ~100 cells, with average harvest rates of 69%, 73%, 79%, and 90%, respectively. To harvest ≥1 cell ≥95% of the time, the system required 3, 5 or 4 live SKBR3, MCF7 or Hs578T cells, respectively. Average harvest rates from precision studies using 5, 10, and ~50 live cells spiked into blood for each cell line ranged from 63.5% to 76.2%, with repeatability and reproducibility percent coefficient of variation (%CV) estimates ranging from 12.3% to 32.4% and 13.3% to 34.1%, respectively. Average harvest rates using ~20 fixed SKBR3 cells spiked into HV and MBC patient blood samples were 75.0% ± 16.1% (%CV = 22.3%) and 68.4% ± 14.3% (%CV = 21.1%), respectively.

Conclusions

These evaluations demonstrate the Parsortix® PC1 system linearly and reproducibly harvests tumor cells from blood over a range of 1 to ~100 cells.