Potential Role of Circulating Tumor Cell Detection and Monitoring in Breast Cancer: A Review of Current Evidence

The prognostic significance of circulating tumor cell enumeration and HER2 expression by a novel automated microfluidic system in metastatic breast cancer

BACKGROUND

The prognostic value of circulating tumor cells (CTCs) in metastatic breast cancer (MBC) has been extensively studied and verified by the CellSearch® system. Varieties of microfluidic systems have been developed to improve capture efficiency with the lack of standardization and automation. This study systematically verified the positive threshold for prognosis and its guidance value in anti-HER2 therapy based on a novel automated microfluidic system OmiCell®.

METHODS

CTCs isolation, enumeration and labeling were performed using the OmiCell® system. CTCs identification and reporting were performed using the DeepSight® scanning system.

RESULTS

The capture efficiency and specificity of OmiCell® system was 91.9% and 90%, respectively. Then, 65 MBC patients with known HER2 status of their metastatic tumors were enrolled. In the cohort, we detected ≥ 1 CTCs in 59 patients (90.8%, range: 1-55 CTCs, median = 6), < 8 CTCs in 45 (69.2%) and ≥ 8 CTCs in 20 (30.8%) patients at baseline. The patients with < 8 CTCs had longer PFS than ≥ 8 CTCs (median, 7 vs. 4.4 months, p = 0.028). CTC enumeration was found to be an independent prognostic factor in our cohort. Moreover, we found a weak concordance between tissue HER2 (tHER2) status and the corresponding CTCs (k = 0.16, p = 0.266). The patients with tHER2 positive and cHER2 negative had better PFS compared with patients with both tHER2 and cHER2 positive (median, 8.2 vs. 3.3 months, p = 0.022).

CONCLUSIONS

This clinical study shows the prognosis value of a new threshold of CTC number and meanwhile the guidance value of cHER2 status in anti-HER2 therapy.

Searching for the "Holy Grail" of breast cancer recurrence risk: a narrative review of the hunt for a better biomarker and the promise of circulating tumor DNA (ctDNA)

BACKGROUND

This paper is a narrative review of a major clinical challenge at the heart of breast cancer care: determining which patients are at risk of recurrence, which require systemic therapy, and which remain at risk in the survivorship phase of care despite initial therapy.

METHODS

We review the literature on prognostic and predictive biomarkers in breast cancer with a focus on detection of minimal residual disease.

RESULTS

While we have many tools to estimate and refine risk that are used to individualize local and systemic therapy, we know that we continue to over treat many patients and undertreat others. Many patients also experience what is, at least in hindsight, needless fear of recurrence. In this review, we frame this dilemma for the practicing breast oncologist and discuss the search for what we term the "holy grail" of breast cancer evaluation: the ideal biomarker of residual distant disease. We review the history of attempts to address this problem and the up-to-date science on biomarkers, circulating tumor cells and circulating tumor DNA (ctDNA).

CONCLUSION

This review suggests that the emerging promise of ctDNA may help resolve a crticical dilemma at the heart of breast cancer care, and improve prognostication, treatment selection, and outcomes for patients with breast cancer.

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.

Circulating Tumor-Derived Endothelial Cells: An Effective Biomarker for Breast Cancer Screening and Prognosis Prediction

Background

Circulating tumor-derived endothelial cell (CTEC) is a new potential tumor biomarker to be associated with cancer development and treatment efficacy. However, few evidences are available for breast cancer.

Methods

Eighty-nine breast cancer patients were recruited, and preoperative and postoperative blood samples were collected. Besides, 20 noncancer persons were enrolled as controls. An improved subtraction enrichment and immunostaining-fluorescence in situ hybridization (SE-iFISH) method was adopted to codetect CD31+ aneuploid CTEC and CD31- aneuploid circulating tumor cell (CTC). Then, the clinical significance of CTCs and CTECs on breast cancer screening and prognosis prediction was evaluated and compared.

Results

The positive rate of CTCs and CTECs in newly diagnosed breast cancer patients was 68.75% and 71.88%. Among detected aneuploid circulating rare cells, CTEC accounts for a greater proportion than CTC in breast cancer patients. CTEC-positive rate and level were significantly higher in breast cancer patients with lymph node metastasis (LNM) than those without LNM (P=0.043), while there was no significant difference in CTC. CTEC (area under the curve, AUC = 0.859) had better performance than CTC (AUC = 0.795) to distinguish breast cancer patients from controls by receiver operator characteristic curve analysis. Preoperative CTEC count ≥ 2 was a significant risk factor for reducing PFS of breast cancer patients.

Conclusions

CTECs may function as a reliable supplementary biomarker in breast cancer screening and prognosis prediction.

Bioconjugates of photon-upconversion nanoparticles for cancer biomarker detection and imaging

The detection of cancer biomarkers in histological samples and blood is of paramount importance for clinical diagnosis. Current methods are limited in terms of sensitivity, hindering early detection of disease. We have overcome the shortcomings of currently available staining and fluorescence labeling methods by taking an integrative approach to establish photon-upconversion nanoparticles (UCNP) as a powerful platform for cancer detection. These nanoparticles are readily synthesized in different sizes to yield efficient and tunable short-wavelength light emission under near-infrared excitation, which eliminates optical background interference of the specimen. Here we present a protocol for the synthesis of UCNPs by high-temperature co-precipitation or seed-mediated growth by thermal decomposition, surface modification by silica or poly(ethylene glycol) that renders the particles resistant to nonspecific binding, and the conjugation of streptavidin or antibodies for biological detection. To detect blood-based biomarkers, we present an upconversion-linked immunosorbent assay for the analog and digital detection of the cancer marker prostate-specific antigen. When applied to immunocytochemistry analysis, UCNPs enable the detection of the breast cancer marker human epidermal growth factor receptor 2 with a signal-to-background ratio 50-fold higher than conventional fluorescent labels. UCNP synthesis takes 4.5 d, the preparation of the antibody-silica-UCNP conjugate takes 3 d, the streptavidin-poly(ethylene glycol)-UCNP conjugate takes 2-3 weeks, upconversion-linked immunosorbent assay takes 2-4 d and immunocytochemistry takes 8-10 h. The procedures can be performed after standard laboratory training in nanomaterials research.

Detection of Minimal Residual Disease in the Peripheral Blood of Breast Cancer Patients, with a Multi Marker (MGB-1, MGB-2, CK-19 and NY-BR-1) Assay

Purpose

Minimal residual disease (MRD) refers to micrometastases that are undetectable by conventional means and is a potential source of disease relapse. This study aimed to detect the presence of breast cancer (BC) biomarkers (MGB-1, MGB-2, CK-19, NY-BR-1) using real-time polymerase chain reaction (RT-PCR) in peripheral blood mononuclear cells (PBMC) of BC patients and the impact of a positive assay on clinical outcome.

Patients and Methods

Patients in the analysis included females >18 years of age with biopsy-proven carcinoma of the breast. A 10 mL sample of venous blood was obtained from 10 healthy controls and 25 breast cancer patients. Comparisons of peripheral blood markers were made with clinicopathological variables.

Results

High-quality RNA was extracted from all samples with a mean RNA concentration of 224.8±155.3 ng/µL. Each of the molecular markers examined was highly expressed in the primary breast tumors (n = 3, positive controls) with none of the markers detected in healthy negative controls. The NY-BR-1 marker was expressed in one (4%) patient with metastatic disease with no MGB-1 and MGB-2 detected in any sample derived from the study patients. The CK-19 marker was detected in 16 (64%) of the BC cases. No correlation was found between CK-19 expression and tumor stage (P = 0.07) or nodal status (P = 0.32). No correlation was identified in the BC patients between CK-19 expression and receptor status in the BC primary tumor.

Conclusion

This study showed high expression of all 4 markers NY-BR-1, MGB-1, MGB-2 and CK-19 in the PBMCs derived from breast cancer patients. CK-19 was detected in 64% of the stage I–III cases operated with curative intent, the only recurrent events occurring in the CK-19-positive cases. Our data confirm the need to enhance techniques for detection of MRD, which may better predict patients at risk for relapse.

Liquid Biopsy in Metastatic Breast Cancer: Current Role of Circulating Tumor Cells and Circulating Tumor DNA

BACKGROUND

In metastatic breast cancer (MBC), blood-based diagnostics have become a major focus of oncological research in the last 2 decades. Detection of circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) has the potential to improve prognosis assessment and complement standard therapy monitoring tools.

SUMMARY

To date, several large analyses have confirmed high CTC counts as an independent prognostic factor. Persistently high CTC numbers during systemic treatment are associated with early progression, but it remains to be clarified which therapeutic options should be offered to such patients since the SWOG 0500 trial failed to show benefit from early switch to another chemotherapy regimen in patients with CTC persistence. In comparison, evidence on the prognostic value of ctDNA is still limited. Most importantly, liquid biopsy-guided treatment interventions have been investigated in several trials. In patients with hormone receptor-positive and HER2-negative MBC, CTC-driven therapy choices resulted in similar PFS to physician's choice treatment. Recently, the DETECT III trial has shown that patients with HER2-negative MBC and HER2-positive CTCs may benefit from targeted anti-HER2 treatment with lapatinib. ctDNA-driven therapy selection has already been approved in clinical routine: alpelisib is the first targeted treatment indicated on the basis of a ctDNA test. Key Messages: CTCs and ctDNA predict clinical outcome and have a potential to improve therapy choices in MBC.

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

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

Circulating tumor cells in peripheral blood of pancreatic cancer patients and their prognostic role: a systematic review and meta-analysis

BACKGROUND

It has been shown that circulating tumor cells in peripheral blood can be used to predict survival in patients with breast, prostate and other epithelial tumors. In the present study, we performed a meta-analysis to evaluate the prognostic role of circulating tumor cells (CTCs) in patients with pancreatic cancer.

METHODS

A systematic literature search of the databases was conducted from the inception to Jul 20, 2019. Relative risks (RRs) with 95% confidence intervals (CIs) were calculated under a fixed or random effect model.

RESULTS

A total of 19 studies with 1320 confirmed individuals were included. Our meta-analysis showed that patients in the CTC-positive group had a significantly shorter overall survival (OS) (RR = 0.47, 95%CI = 0.33-0.61, P < 0.001) and progression-free survival (PFS) (P = 0.003) than CTC-negative patients. Moreover, subgroup analysis by ethnicity indicated that CTC-positive patients had a significantly shorter OS in both Asian and Western populations. Further subgroup analysis by detection methods, treatments, and Tumor Node Metastasis (TNM) stages also indicated that CTC-positive patients were associated with significant decreases in both OS and PFS  in most subgroups.

CONCLUSION

Our meta-analysis indicates that CTC-positive patients have a worse OS and PFS than CTC-negative patients, which suggests that CTCs may act as predictive biomarkers for pancreatic cancer patients before treatment.

Clinical Relevance and Therapeutic Application of CTCs in Advanced Breast Cancer

Precision medicine through liquid biopsy represents an emerging approach in the management of cancer. The CTC count in blood samples from patients with advanced breast cancer is a powerful prognostic factor for both progression free and overall survival. Moreover, high levels of CTCs at any time during the treatment can reliably predict progression before imaging studies and/or tumor markers. Furthermore, there are works on the molecular characterization of the CTCs and their potential ability to guide the treatment in a dynamic way. However, their role remains controversial. Detection and enumeration of CTCs is variable among different tumors and is subjected to biases related mainly to their methodology, which is not completely standardized. In addition, they must demonstrate their clinical value to guide the treatment and a translation on patient's survival.

53BP1 Accumulation in Circulating Tumor Cells Identifies Chemotherapy-Responsive Metastatic Breast Cancer Patients

Evidence suggests that the DNA end-binding protein p53-binding protein 1 (53BP1) is down-regulated in subsets of breast cancer. Circulating tumor cells (CTCs) provide accessible “biopsy material” to track cell traits and functions and their alterations during treatment. Here, we prospectively monitored the 53BP1 status in CTCs from 67 metastatic breast cancer (MBC) patients with HER2- CTCs and known hormone receptor (HR) status of the primary tumor and/or metastases before, during, and at the end of chemotherapeutic treatment with Eribulin. Nuclear 53BP1 staining and genomic integrity were evaluated by immunocytochemical and whole-genome-amplification-based polymerase chain reaction (PCR) analysis, respectively. Comparative analysis of CTCs from patients with triple-negative and HR+ tumors revealed elevated 53BP1 levels in CTCs from patients with HR+ metastases, particularly following chemotherapeutic treatment. Differences in nuclear 53BP1 signals did not correlate with genomic integrity in CTCs at baseline or with nuclear γH2AX signals in MBC cell lines, indicating that 53BP1 detected features beyond DNA damage. Kaplan–Meier analysis revealed an increasing association between nuclear 53BP1-positivity and progression-free survival (PFS) during chemotherapy until the final visit. Our data suggest that 53BP1 detection in CTCs could be a useful marker to capture dynamic changes of chemotherapeutic responsiveness in triple-negative and HR+ MBC.

Metabolic classification of circulating tumor cells as a biomarker for metastasis and prognosis in breast cancer

Background

Circulating tumor cells (CTCs) has been demonstrated as a promising liquid biopsy marker for breast cancer (BC). However, the intra-patient heterogeneity of CTCs remains a challenge to clinical application. We aim at profiling aggressive CTCs subpopulation in BC utilizing the distinctive metabolic reprogramming which is a hallmark of metastatic tumor cells.

Methods

Oncomine, TCGA and Kaplan–Meier plotter databases were utilized to analyze expression and survival relevance of the previously screened metastasis-promoting metabolic markers (PGK1/G6PD) in BC patients. CTCs detection and metabolic classification were performed through micro-filtration and multiple RNA in situ hybridization using CD45 and PGK1/G6PD probes. Blood samples were collected from 64 BC patients before treatment for CTCs analysis. Patient characteristics were recorded to evaluate clinical applications of CTCs metabolic subtypes, as well as morphological EMT subtypes classified by epithelial (EpCAM/CKs) and mesenchymal (Vimentin/Twist) markers.

Results

PGK1 and G6PD expressions were up-regulated in invasive BC tissues compared with normal mammary tissues. Increased tissue expressions of PGK1 or G6PD indicated shortened overall and relapse-free survival of BC patients (P < 0.001). Blood GM⁺CTCs (DAPI⁺CD45⁻PGK1/G6PD⁺) was detectable (range 0–54 cells/5 mL) in 61.8% of tCTCs > 0 patients. Increased GM⁺CTCs number and positive rate were correlated with tumor metastasis and progression (P < 0.05). The GM⁺CTCs ≥ 2/5 mL level presented superior AUC of ROC at 0.854 (95% CI 0.741–0.968) in the diagnosis of BC metastasis (sensitivity/specificity: 66.7%/91.3%), compared with that of tCTCs (0.779) and CTCs-EMT subtypes (E-CTCs 0.645, H-CTCs 0.727 and M-CTCs 0.697). Moreover, GM⁺CTCs⁺ group had inferior survival with decreased 2 years-PFS proportion (18.5%) than GM⁺CTCs⁻ group (87.9%; P = 0.001).

Conclusions

This work establishes a PGK1/G6PD-based method for CTCs metabolic classification to identify the aggressive CTCs subpopulation. Metabolically active GM⁺CTCs subtype is suggested a favorable biomarker of distant metastasis and prognosis in BC patients.

Circulating Tumor Cells in Breast Cancer

With active screening for early detection and advancements in treatment, there has been a significant decrease in mortality from breast cancer. However, a significant proportion of patients with non-metastatic breast cancer at time of diagnosis will relapse. Therefore, it is suggested that the dissemination of bloodstream tumor cells (circulating tumor cells, CTCs) undetectable by currently available diagnostic tools occurs during the early stages of breast cancer progression, and may be the potential source of micrometastases responsible for treatment failures. Here, we review the clinical significance of CTCs, as detected by the FDA-approved CellSearch^® System, in both metastatic and non-metastatic breast cancer patients. Studies so far suggest that CTCs are prognostic of poorer outcomes in breast cancer patients; however, there is currently insufficient data to support use of CTC data to guide treatment. Therefore, there are ongoing studies to evaluate the utility of assessing CTC phenotypes to develop personalized breast cancer treatment, which will be reviewed in this chapter.

Circulating and Disseminated Tumor Cells in Breast Carcinoma: Report from the Consensus Conference on Tumor Cell Dissemination during the 39th Annual Meeting of the German Society of Senology, Berlin, 27 June 2019

Hematogenous dissemination of single tumor cells from the primary tumor is a common phenomenon in most solid malignancies. In breast cancer, presence of circulating tumor cells (CTCs) in the peripheral blood and disseminated tumor cells (DTCs) in bone marrow predicts poor clinical outcome, both in early and metastatic setting. Beyond that, persistence of CTCs/DTCs is associated with shorter relapse-free interval as well. Numerous studies have shown that these cells differ from tumor cells in the primary tumor with regard to hormone and HER2 receptor status and it has been hypothesized that some of them might be in fact cancer stem cells. Recently, the first positive study on CTC-based therapy interventions has been presented at the San Antonio Breast Cancer Symposium 2018, demonstrating that detection of CTCs may guide treatment decisions in metastatic HR-positive HER2-negative disease. In this review, we present the current state of evidence of tumor cell dissemination and discuss the implications for future trials.

Impact of uPA/PAI-1 and disseminated cytokeratin-positive cells in breast cancer

BACKGROUND

The protease uPA and its inhibitor PAI-1 play major roles in hemostasis and are also involved in cancer progression. This is mainly caused by their ability to degrade extracellular matrix-facilitating tumor cell migration. This study aimed to investigate the impact of uPA/PAI-1 and disseminated cytokeratin-positive cells (dCK+) on the outcome and the existence of synergistic effects.

METHODS

We retrospectively analyzed a cohort of 480 breast cancer cases with known uPA/PAI-1 and dCK+ status. uPA/PAI-1 was tested on fresh tumor samples using a commercial ELISA test. Bone marrow aspirates were investigated immunocytochemically for CK18.

RESULTS

DCK+ cells were identified in 23% of cases. uPA positivity was significantly associated with the occurrence of dCK+ cells (P = 0.028). uPA and PAI-1 were significantly associated with outcome in the subgroup of early-stage cases without chemotherapy. DCK+ cells alone were not prognostic. However, we found synergistic effects. In the subgroup of node-negative cases with and without chemotherapy, the prognostic impact of uPA and PAI-1 was enhanced in cases with additional dCK-positivity (triple +). In cases without chemotherapy, triple-positive status was independently prognostic (HR: 9.3 CI: 1.1-75) next to T stage.

CONCLUSIONS

uPA and PAI-1 seem to influence the metastatic potential of dCK+ cells, which underlines its important role in tumor progression.

Label-Free Enrichment and Molecular Characterization of Viable Circulating Tumor Cells from Diagnostic Leukapheresis Products

INTRODUCTION

Circulating tumor cells (CTCs) may be used to improve cancer diagnosis, prognosis, and treatment. However, because knowledge regarding CTC biology is limited and the numbers of CTCs and CTC-positive cancer patients are low, progress in this field is slow. We addressed this limitation by combining diagnostic leukapheresis (DLA) and microfluidic enrichment to obtain large numbers of viable CTCs from metastasized breast cancer patients.

METHODS

DLA was applied to 9 patients, and 7.5 mL of peripheral blood was drawn. CTCs were enriched with the Parsortix™ system. The quality of CTCs from fresh and cryopreserved DLA products was tested, and CTCs were cultured in vitro. Single uncultured and cultured CTCs were isolated by micromanipulation to determine different parameters, such as genomic aberrations and mutation profiles of selected tumor-associated genes. Expression levels of estrogen receptor and HER2/neu were monitored during in vitro culture.

RESULTS

Viable CTCs from peripheral blood and fresh or frozen DLA products could be enriched. DLA increased the likelihood of successful CTC culture. Cryopreserved DLA products could be stored with minimal CTC loss and no overt reduction in the tumor cell quality and viability during an observation period of up to 3 years. The analyzed parameters did not change during in vitro culture. DLA samples with high CTC numbers and lower ratios of apoptotic CTCs were more likely to grow in culture.

CONCLUSIONS

The increased CTC numbers from fresh or cryopreserved DLA products facilitate multiple functional and molecular analyses and, thus, could improve our knowledge of their biology.

Development and Validation of Multiplex Liquid Bead Array Assay for the Simultaneous Expression of 14 Genes in Circulating Tumor Cells

Liquid biopsy, based on the molecular information extracted from circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), offers the possibility to characterize the evolution of a solid tumor in real time and is highly important for diagnostic and therapeutic purposes. The aim of the present study was the development and validation of a novel liquid bead array methodology for the molecular characterization of CTCs and its application in breast cancer. In the present study we developed and evaluated a multiplex polymerase chain reaction (PCR)-coupled liquid bead array (MLBA) assay for studying simultaneously the expression of 14 genes in CTCs. The 14-gene MLBA assay is characterized by high analytical specificity, sensitivity, and reproducibility. The analytical performance of the 14-gene MLBA assay was compared with a commercially available test (AdnaTest BreastCancer, Qiagen, Germany) and our previously described multiplex quantitative reverse transcription PCR (RT-qPCR) assays. The developed assay has the potential to be further expanded in order to include up to 100 gene targets. The assay is highly specific for each target gene and is not affected by the numerous primers and probes used for multiplexing; hence, it constitutes a sample-, cost-, and time-saving analysis.

Epithelial membrane protein 2: a novel biomarker for circulating tumor cell recovery in breast cancer

PURPOSE

EpCAM is a common marker used in the detection of circulating tumor cells (CTC). Disseminated cancer cells display the characteristics of epithelial-to-mesenchymal transition events. The purpose of this study was to assess the potential of epithelial membrane protein 2 (EMP2) as a novel biomarker for CTC retrieval in breast cancer.

METHODS

MCF7 and MDA-MB-231 cells were stained with either anti-EpCAM or anti-EMP2 mAbs, respectively, followed by flow cytometric assay to measure their expression levels. PBMCs isolated from healthy donors were used for breast cancer cell spiking. CD45-depleted PBMCs from breast cancer patients' blood were used for CTC capturing. Immunomagnetic separation was used to enrich breast cancer cells. Cytospin centrifugation was performed to concentrate the captured cells, followed by immunofluorescence staining with anti-CD45 mAb, anti-pan cytokeratin mAb and DAPI. Fluorescent images were taken using a confocal microscope for CTC counts.

RESULT

MDA-MB-231 cells had 2.56 times higher EMP2 expression than MCF7 cells, and EMP2 had a significantly higher capture efficiency than EpCAM for MCF7 cells. Furthermore, anti-EMP2 was capable of capturing MCF7 cells that escaped in the flow-through of anti-EpCAM. Likewise, EMP2 had a significantly higher capture efficiency on MDA-MB-231 cells when compared to MCF7 cells. Most importantly, EMP2 biomarker was successfully used for CTC capture in patients with primary breast cancer.

CONCLUSIONS

EMP2 is superior to EpCAM for capturing both MCF7 and MDA-MB-231 cells. Additionally, EMP2 is a novel biomarker and capable of capturing breast cancer cells in patient blood samples.

Early discovery of disseminated tumor cells during carcinogenesis in a 4NQO-induced mouse model of oral squamous cell carcinoma

OBJECTIVES

Heterogeneous cells appear in multiple organs during the same time period as the primary lesion of some tumors is clinically detected. These heterogeneous cells are also known as disseminated tumor cells (DTCs). However, the characteristics of DTCs that disseminate during oral carcinogenesis remain unclear.

MATERIALS AND METHODS

A mouse 4NQO model of lymph node metastasis in oral squamous cell carcinoma was established. Tissue samples of the tongue, bone marrow and submandibular lymph node were collected. Five stages (stage 0~stage IV) of carcinogenesis in each experimental animal were classified by two pathologists. After immunohistochemical staining of cytokeratin, the DTCs were isolated from bone marrow samples (stage II) by the laser capture microdissection (LCM) technique during oral carcinogenesis. Genomic amplification of bone marrow DTCs was performed, and homozygous deletion of the RB1CC1 gene was analyzed. After confirming the presence of disseminated tumor cells in stage II bone marrow samples, a comprehensive study among various stages of lymph node tissue was conducted using the same method.

RESULTS

DTCs that spread from the primary tumor were discovered in stage II bone marrow samples and in stage I, stage II and stage III submandibular lymph node samples through immunohistochemical staining. These spreading cells had different levels of homozygous exon deletion in the RB1CC1 and TP53 genes.

CONCLUSION

Early spreading of epithelial cells may occur during the carcinogenesis of oral cancer. DTCs of oral carcinoma may show different chromosome aberrations from matched primary tumor cells.

Tunicamycin suppresses breast cancer cell growth and metastasis via regulation of the protein kinase B/nuclear factor-κB signaling pathway

Breast cancer is one of the most common metastatic tumor types. Reports have suggested that Tunicamycin may inhibit the aggressiveness of cancer cells by promoting their apoptosis. In the present study, the inhibitory effects of Tunicamycin were investigated and the potential molecular mechanism underlying the Tunicamycin-inhibited growth and aggressiveness of breast cancer cells was explored. In vitro assays demonstrated that Tunicamycin significantly inhibited growth and arrested the cell cycle of breast cancer cells in a dose-dependent manner, compared with control cells. Results revealed that Tunicamycin treatment suppressed the migration and invasion of breast cancer cells. Significantly increased apoptosis of breast cancer cells was observed subsequent to Tunicamycin treatment, as compared with control cells. Mechanism analysis demonstrated that Tunicamycin inhibited the protein kinase B (Akt) and nuclear factor-κB (NF-κB) signaling pathways, whilst Akt overexpression significantly cancelled out the Tunicamycin-inhibited growth and aggressiveness of breast cancer cells, as compared with control cells. In vivo assays revealed that Tunicamycin treatment significantly inhibited tumor growth and significantly prolonged the survival of tumor-bearing mice, compared with the PBS-treated group. In conclusion, these results indicate that Tunicamycin may inhibit the growth and aggressiveness of breast cancer cells via regulation of the Akt/NF-κB signaling pathway.

Nanotechnology-Based Strategies for Early Cancer Diagnosis Using Circulating Tumor Cells as a Liquid Biopsy

Circulating tumor cells (CTCs) are cancer cells that shed from a primary tumor and circulate in the bloodstream. As a form of “tumor liquid biopsy”, CTCs provide important information for the mechanistic investigation of cancer metastasis and the measurement of tumor genotype evolution during treatment and disease progression. However, the extremely low abundance of CTCs in the peripheral blood and the heterogeneity of CTCs make their isolation and characterization major technological challenges. Recently, nanotechnologies have been developed for sensitive CTC detection; such technologies will enable better cell and molecular characterization and open up a wide range of clinical applications, including early disease detection and evaluation of treatment response and disease progression. In this review, we summarize the nanotechnology-based strategies for CTC isolation, including representative nanomaterials (such as magnetic nanoparticles, gold nanoparticles, silicon nanopillars, nanowires, nanopillars, carbon nanotubes, dendrimers, quantum dots, and graphene oxide) and microfluidic chip technologies that incorporate nanoroughened surfaces and discuss their key challenges and perspectives in CTC downstream analyses, such as protein expression and genetic mutations that may reflect tumor aggressiveness and patient outcome.

Circulating tumour cell PD-L1 test for head and neck cancers

Immune checkpoint inhibitors have gained traction over the last few years in the treatment of metastatic/recurrent head and neck squamous cell carcinoma (HNSCC) patients. Monoclonal antibodies that block the programmed death 1 (PD-1) receptor and its major ligand, PD-L1, have shown durable responses and low toxicity profiles. There are currently no validated predictive biomarkers to select patients likely to respond to anti-PD-1/PD-L1 therapy to avoid unwanted side effects and to reduce healthcare expenditure. A circulating tumour cell (CTC) PD-L1 assay could be developed as a companion diagnostic tool to potentially predict the efficacy of immune checkpoint blockade treatments.

Circulating tumor cells in the differential diagnosis of adnexal masses

The aim of this study was to evaluate circulating tumor cell (CTC) detection in the differential diagnosis of adnexal masses. A total of 87 preoperative women with an indeterminate adnexal mass were prospectively enrolled. Preoperative diagnostic modalities including CTC detection, risk of ovarian malignancy algorithm, risk of malignancy index, and computed tomography or magnetic resonance imaging were compared. Forty-three (49.4%) benign tumors, 13 (14.9%) borderline malignant masses, and 31 (35.7%) cancers were pathologically confirmed. Forty-nine (56.3%) cases were positive for CTCs: 19/43 (44.2%) benign, 10/10 (100%) early-stage, and 14/21 (66.7%) advanced-stage cancer. CTC detection had sensitivities of 77.4%, 100%, and 100% for benign vs. all stage cancer (n = 74), benign vs. stage I–II cancer (n = 53), and benign vs. stage I cancer (n = 49), respectively. CTC detection had a specificity of 55.8% across all comparisons. The sensitivities of the other modalities assayed were decreased in stage I–II cancer and stage I cancer vs. benign masses. Receiver operating characteristic curves showed that CTCs, of which the area under the curve was modest in all stage cancer (0.655), had the widest area under the curve among the evaluated modalities in stage I–II cancer and stage I cancer (0.768 for both). In conclusion, our study findings suggest that preoperative CTCs could have a substantial role in differentiating early stage cancer from benign tumors for adnexal masses.

Size-based detection of sarcoma circulating tumor cells and cell clusters

Metastatic disease is the most important factor in determining the survival of sarcoma patients. Since sarcoma metastasis is predominantly hematogenous, we hypothesized that detection and quantification of circulating tumor cells (CTCs) could reflect response to therapy and risk of metastatic relapse. We evaluated the presence of CTCs using a novel animal model and in the blood of patients with high grade sarcomas utilizing the CellSieve™ size-based low pressure microfiltration system. Sarcoma CTCs were identified based on antibody staining patterns and nuclear morphology. Additionally, RNA was extracted from the CTCs for molecular analysis including demonstration of an EWS-FLI1 translocation, identification of a previously unrecognized p53 mutation in a patient with Ewing sarcoma, and single cell RNA sequencing of CTC from a child with alveolar rhabdomyosarcoma. In mouse xenograft models, the presence of CTC correlates with disease burden and with clinically silent metastases. In human patients, CTCs were readily detected at diagnosis, decreased with successful treatment, and were detectable in the blood of patients with no radiographic evidence of disease prior to the development of overt metastasis. Although evaluation of CTC is established in the care of patients with carcinomas, this technology has yet to be effectively applied to the evaluation and treatment of sarcoma patients. Our work demonstrates that the CellSieve™ microfiltration system can be used to study the biology of CTC in both mouse models and human sarcoma patients, with the potential for application to the monitoring of disease response and prediction of metastatic relapse.

Circulating tumor cells and their role in prostate cancer

Circulating tumor cells (CTC) have become an important biomarker in patients with advanced prostate cancer. CTC count has been demonstrated to be a prognostic factor for overall survival in patients with metastatic castration-resistant prostate cancer (mCRPC). In localized prostate cancer, a clear correlation between CTC counts and clinicopathological risk parameters and outcome has not been observed. Currently, the focus of research is shifting from CTC enumeration towards molecular characterization of CTC leading to the discovery of markers predicting treatment response. The role of androgen receptor splice variants expressed by CTC as markers of resistance to abiraterone and enzalutamide has been assessed by various studies. The identification of CTC markers predicting treatment response represents a key step to guide the selection of treatment (e.g., abiraterone/enzalutamide vs taxanes), particularly in patients with mCRPC. As an alternative to CTC, the analysis of circulating tumor DNA has been shown to enable a noninvasive disease characterization having high potential to promote precision oncology.

Molecular characterization and heterogeneity of circulating tumor cells in breast cancer

Introduction

This study analyzes peripheral blood samples from breast cancer (BC) patients. CTCs from peripheral blood were enriched by size-based separation and were then cultivated in vitro. The primary aim of this study was to demonstrate the antigen independent CTC separation method with high CTC recovery. Subsequently, CTCs enriched several times during the treatment were characterized molecularly.

Methods

Patients with different stages of BC (N = 167) were included into the study. All patients were candidates for surgery, surgical diagnostics, or were undergoing chemotherapy. In parallel, 20 patients were monitored regularly and in addition to CTC presence, also CTC character was examined by qPCR, with special focus on HER2 and ESR status.

Results

CTC positivity in the cohort was 76%. There was no significant difference between the tested groups, but the highest CTC occurrence was identified in the group undergoing surgery and similarly in the group before the start of neoadjuvant treatment. On the other hand, the lowest CTC frequencies were observed in the menopausal patient group (56%), ESR+ patient group (60%), and DCIS group (44.4%). It is worth noting that after completion of neoadjuvant therapy (NACT) CTCs were present in 77.7% of cases. On the other hand, patients under hormonal treatment were CTC positive only in 52% of cases.

Discussions

Interestingly, HER2 and ESR status of CTCs differs from the status of primary tumor. In 50% of patients HER2 status on CTCs changed not only from HER2+ to HER2−, but also from HER2– to HER2+ (33%). ESR status in CTCs changed only in one direction from ESR+ to ESR−.

Conclusions

Data obtained from the present study suggest that BC is a heterogeneous disease but CTCs may be detected independently of the disease characteristics in 76% of patients at any time point during the course of the disease. This relatively high CTC occurrence in BC should be considered when planning the long-term patient monitoring.

Role of Circulating Tumor Cell (CTC) Monitoring in Evaluating Prognosis of Triple-Negative Breast Cancer Patients in China

Background

Breast cancer (BC) is the most common malignant tumor in females. This study investigated the role and utility of CTC monitoring in evaluating the prognosis of triple-negative breast cancer patients.

Material/Methods

We enrolled 286 female triple-negative breast cancer patients who were diagnosed at and received radical resection surgery in our hospital. Peripheral venous blood samples were collected preoperatively and at 3 and 7 days postoperative, and the Cell Search system was used to detect CTC in peripheral blood. We analyzed the relationship between preoperative CTC level and clinical pathological characteristics of patients. Kaplan-Meier method was used to establish progression-free survival curves and overall survival curves, we used the log-rank test to compare the survival rate, and we explored the effects of preoperative and postoperative CTC levels on patient survival.

Results

Compared with preoperative levels, the average CTC content in peripheral blood of breast cancer patients was significantly increased at 3 days after surgery, and then decreased to the preoperative baseline level by 7 days after surgery. The 3-year overall survival rate and progression-free survival rate in patients with CTC >5/7.5 mL peripheral blood were significantly lower than in patients with CTC <5/7.5 mL peripheral blood detected preoperatively and at 3 and 7 days postoperatively.

Conclusions

Dynamic monitoring of preoperative and postoperative CTC levels can accurately predict recurrence and progression of disease, and is important in postoperative monitoring and prognosis evaluation.

Stress granules assembly affects detection of mRNA in living cells by the NanoFlares; an important aspect of the technology

The recently announced new methodologies to detect mRNA molecules in single cells offer opportunities for research, medicine and molecular diagnostics. The NanoFlare RNA Detection Probes are tools for characterizing RNA content (not localization) using fluorescence-based approaches in living cells. Combined with flow cytometry, NanoFlares have expanded the available possibilities of quantitative analysis of mRNA level in a single cell. Herein we present that in some cases, the specific NanoFlare probes (SmartFlares) detect different amounts of mRNA compared to qPCR. Using the previously published model, in which we studied influence of BCR-ABL oncogene on BRCA1 mRNA translation, we found that the NanoFlare-mediated measurement of mRNA was affected by the assembly of stress granules, structures which store mRNA in complexes with RNA binding proteins. With the usage of chemical compounds we confirmed that under conditions supporting assembly of stress granules, the detection of mRNAs by these probes was decreased, whereas disassembly resulted in the increased mRNAs detection. Altogether, we showed that assembly of stress granules could interfere with mRNA accessibility to the NanoFlare RNA Detection Probes, indicating that the SmartFlares could recognize only the translationally active pool of mRNA, contrary to qPCR. This can significantly influence the quality of obtained data and should be taken into consideration while planning the analysis of mRNA markers using NanoFlares.