Characterization of Urothelial Cancer Circulating Tumor Cells with a Novel Selection-Free Method

Liquid biopsies for detection, surveillance, and prognosis of urothelial cancer: a future standard?

INTRODUCTION

Liquid biopsies are used for the detection of tumor-specific elements in body fluid. Their application in prognosis and diagnosis of muscle/non-muscle invasive bladder cancer (MIBC/NMIBC) or upper tract urothelial cancer (UTUC) remains poorly known and rarely mentioned in clinical guidelines.

AREAS COVERED

Herein, we provide an overview of current data regarding the use of liquid biopsies in urothelial tumors.

EXPERT OPINION

Studies that were included analyzed liquid biopsies using the detection of circulating tumor cells (CTCs), deoxyribonucleic acid (DNA), ribonucleic acid (RNA), exosomes, or metabolomics. The sensitivity of blood CTC detection in patients with localized cancer was 35% and raised to 50% in patients with metastatic cancer. In NMIBC patients, blood CTC was associated with poor prognosis, whereas discrepancies were seen in MIBC patients. Circulating plasma DNA presented a superior sensitivity to urine and was a good indicator for diagnosis, follow-up, and oncological outcome. In urine, specific bladder cancer (BC) microRNA had an overall sensitivity of 85% and a specificity of 86% in the diagnosis of urothelial cancer. These results are in favor of the use of liquid biopsies as biomarkers for in urothelial cancer management.

Consistency evaluation of lung adenocarcinoma tissue and circulating tumor cells related gene mutation detection based on multi-site immunomagnetic beads

This study was designed to investigate the feasibility of genetic testing using circulating tumor cells (CTCs) instead of tumor tissues in lung adenocarcinoma to break through its limitation. Separation system for epithelial cell adhesion molecule (EpCAM), epidermal growth factor receptor (EGFR), and Vimentin expressing CTCs was constructed and used to capture CTCs in the blood samples of 57 patients with lung adenocarcinoma. Genetic mutations of genes involved in targeted therapies were detected by next-generation sequencing (NGS) in tissues from these patients. Blood CTC samples with the gene mutations identified by tissue-NGS were selected and corresponding gene mutations were detected by Sanger sequencing. The specificity of the CTC separation system was 95.48% and the sensitivity was 90.85%. The average number of CTCs in the blood of patients with lung adenocarcinoma was 12.47/7.5 mL. Comparison of the tissue-NGS with the CTC-Sanger sequencing showed that the consistencies of genetic mutations of EGFR (n = 24), KRAS (n = 9), TP53 (n = 19), BRAF (n = 1), ERBB2 (n = 2), and PIK3CA (n = 3) were 92.31%, 75.00%, 86.36%, 50.00%, 66.67%, and 75.00%, with an overall consistency of 84.06%. The CTC separation system established in this study shows high specificity and sensitivity. CTCs can be used as a suitable alternative to tumor tissues that are difficult to obtain in clinical practice and overcome the difficulties in tumor tissue collection, which is of significance in guiding clinical medication and individualized treatment with significant clinical application value in terms of genetic testing for targeted therapies in tumor treatment.

Correlation between High PD-L1 and EMT/Invasive Genes Expression and Reduced Recurrence-Free Survival in Blood-Circulating Tumor Cells from Patients with Non-Muscle-Invasive Bladder Cancer

BACKGROUND

PD-L1 represents a crucial immune checkpoint molecule in the tumor microenvironment, identified as a key target for cancer immunotherapy. A correlation between PD-L1 and EMT-related genes expression in various human cancers has been suggested.

METHODS

By ScreenCell filtration, digital droplet PCR and confocal microscopy analysis, we aimed to investigate the expression of PD-L1 and EMT/invasive genes (TWIST1, ZEB1, VIMENTIN, TIMP2) in circulating tumor cells (CTCs) collected from the blood of non-muscle-invasive bladder cancer (NMIBC) patients, assessing the prognostic value of these biomarkers in the disease. Welchs' test and Mann-Whitney U test, correlation index, Kaplan-Meier, Univariate and Multivariate Cox hazard proportional analysis were used.

RESULTS

Higher PD-L1, TIMP2 and VIM mRNA levels were found in pT1 compared to pTa NMIBC. As evaluated by Kaplan-Meier and Univariate and Multivariate Cox analysis, enhancement of PD-L1, TWIST1 and TIMP2 expression reduces the recurrent free survival in NMIBC patients.

CONCLUSIONS

High PD-L1, TWIST1 and TIMP2 mRNAs mark the recurrent-NMIBC patients and by reducing the RFS represent negative prognostic biomarkers in these patients.

Clinical verification of vimentin/EpCAM immunolipid magnetic sorting system in monitoring CTCs in arterial and venous blood of advanced tumor

BACKGROUND

Circulating tumor cells (CTCs) are the dominant factor leading to tumor metastasis. This study aims to investigate the effect of disparate sources of CTCs on the treatment and prognosis of patients with advanced tumors by analyzing the number and gene mutations change of CTCs in arterial and venous blood in patients with advanced tumors.

RESULTS

A CTCs sorting system was constructed based on Vimentin-immunolipid magnetic balls (Vi-IMB) and EpCAM immunolipid magnetic balls (Ep-IMB). Results showed that the prepared Ep-IMB and Vi-IMB had lower cytotoxicity, better specificity and sensitivity. The number of arterial CTCs was higher than that of venous CTCs, with a statistically significant difference (P < 0.05). Moreover, the prognosis of the low positive group of total CTCs in arterial blood and venous blood was higher than that of the high positive group, with a statistical significance (P < 0.05). The genetic testing results showed that the targeted drug gene mutations in tissues, arterial CTCs and venous CTCs showed a complementary trend, indicating that there was heterogeneity among different tumor samples.

CONCLUSIONS

CTCs in blood can be efficiently captured by the CTCs sorting system based on Vi-LMB/Ep-LMB, and CTCs detection in arterial blood can be utilized to more accurately evaluate the prognosis and predict postoperative progress. It is further confirmed that tumor samples from disparate sources are heterogeneous, providing a reference basis for gene mutation detection before clinical targeted drug treatment, and the detection of CTCs in arterial blood has more potential clinical application value.

TRIAL REGISTRATION

The Ethics Committee of Putuo Hospital, PTEC-A-2019-18-1. Registered 24 September 2019.

Liquid Biopsies to Select Patients for Perioperative Chemotherapy in Muscle-invasive Bladder Cancer: A Systematic Review

CONTEXT

Neoadjuvant chemotherapy (NAC) is considered the standard treatment for muscle-invasive bladder cancer (MIBC). However, its overall survival benefit is limited and toxicity is significant; hence, NAC has not been adopted universally.

OBJECTIVE

To systematically evaluate whether biomarkers can guide the administration of perioperative chemotherapy in MIBC patients.

EVIDENCE ACQUISITION

A systematic search of the PubMed database was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). In total, 215 papers were screened and 22 were selected to assess the potential clinical value of circulating tumor cells (CTCs) and cell-free DNA (cfDNA) in selecting MIBC patients for perioperative chemotherapy.

EVIDENCE SYNTHESIS

We found that the presence of one or more CTCs before radical cystectomy, as determined by the CellSearch technique, is a robust marker for poor recurrence-free and overall survival. Consequently, whether NAC can be withheld in patients without the presence of CTCs is a subject of ongoing investigation. Studies investigating various approaches to detect cfDNA showed that cfDNA is present in the blood of MIBC patients, but varying results on its prognostic value have been reported. Successful cfDNA-based approaches are likely to encompass at least a multitude of genes using next-generation sequencing, as there are generally few hotspot somatic mutations in MIBC.

CONCLUSIONS

Liquid biopsies hold promise in selecting MIBC patients for perioperative chemotherapy, but instead of more proof-of-principle studies, prospective studies investigating true clinical applicability for treatment decision making are urgently needed.

PATIENT SUMMARY

Liquid biopsies appear to be a promising tool to guide the administration of chemotherapy in patients with muscle-invasive bladder cancer; however, the optimal way to implement these remains to be determined.

Analysis of the Circulating Tumor Cell Capture Ability of a Slit Filter-Based Method in Comparison to a Selection-Free Method in Multiple Cancer Types

Circulating tumor cells (CTCs) are a promising biomarker for cancer liquid biopsy. To evaluate the CTC capture bias and detection capability of the slit filter-based CTC isolation platform (CTC-FIND), we prospectively compared it head to head to a selection-free platform (AccuCyte^®-CyteFinder^® system). We used the two methods to determine the CTC counts, CTC positive rates, CTC size distributions, and CTC phenotypes in 36 patients with metastatic cancer. Between the two methods, the median CTC counts were not significantly different and the total counts were correlated (r = 0.63, p < 0.0001). The CTC positive rate by CTC-FIND was significantly higher than that by AccuCyte^®-CyteFinder^® system (91.7% vs. 66.7%, p < 0.05). The median diameter of CTCs collected by CTC-FIND was significantly larger (13.0 μm, range 5.2–52.0 vs. 10.4 μm, range 5.2–44.2, p < 0.0001). The distributions of CTC phenotypes (CK+EpCAM+, CK+EpCAM− or CK−EpCAM+) detected by both methods were similar. These results suggested that CTC-FIND can detect more CTC-positive cases but with a bias toward large size of CTCs.

Sorting and gene mutation verification of circulating tumor cells of lung cancer with epidermal growth factor receptor peptide lipid magnetic spheres

Background

This study aimed to identify an efficient, simple, and specific method of detecting mutations in the epidermal growth factor receptor (EGFR) gene in isolated lung cancer circulating tumor cells (CTCs) and to improve the ability to obtain tumor tissue clinically.

Methods

EGFR peptide lipid magnetic spheres (EG‐P‐LMB) were prepared by reverse evaporation, and characterization and cell capture efficiency assessed. The peripheral blood samples of 30 lung cancer patients were isolated and identified with the EG‐P‐LMB using 20 healthy volunteers as controls. Finally, the isolated CTCs were tested for EGFR gene mutations, and the tissue samples selected for comparison.

Results

The prepared magnetic spheres had a smaller particle size and higher stability according to the particle size potential test. Their morphology was homogeneous by atomic force observation, and the UV test showed that there were peptides on the surface. The separation efficiency of EG‐P‐LMB was greater than 90% in PBS and greater than 80% in the blood simulation system. Compared with the tissue sample results, the positive rate of EGFR gene mutations was 94%. The CTC test results of 27 patients were consistent with the tissue test results of the corresponding patients, and the consistency with the tissue comparison test results was 90% (27/30).

Conclusions

EG‐P‐LMB can effectively capture CTCs in the peripheral blood of patients with lung cancer. CTC detection can accurately identify mutations in the EGFR gene and improve the ability to obtain tumor tissue in clinical practice.

Key points

Significant findings of the study

EG‐P‐LMB can effectively capture CTCs in the peripheral blood of patients with lung cancer. CTC detection can accurately identify mutations in the EGFR gene and improve the ability to obtain tumor tissue in clinical practice.

What this study adds

This study added EGFR peptide lipid magnetic spheres to capture CTCs in the blood. Genetic testing was performed and compared with tissues. It solves the problem of clinically difficult tumor tissue sampling.

The combination of size-based separation and selection-free technology provides higher circulating tumour cells detection sensitivity than either method alone in patients with metastatic prostate cancer

OBJECTIVE

To investigate the circulating tumour cells (CTCs) capture abilities of two technologies that are not dependent on cell-surface marker expression: a selection-free platform [AccuCyte^® -CyteFinder^® system (Rarecyte)] and a size-based platform [fluid-assisted separation technology (FAST)]. In addition, the combination of the two systems to more completely assess CTCs was investigated.

PATIENTS AND METHODS

In all, 28 patients with metastatic prostate cancer were included. Two 6 mL peripheral blood samples were taken from each patient at the same time-point. The samples were then subjected to the two different technology platforms in parallel. An additional group of samples was acquired by applying the waste chamber material from the FAST-group tests (flow-through that goes through the FAST filter membrane) to the Rarecyte system for the detection any CTCs that were not captured by FAST.

RESULTS

The three groups had significantly different putative CTC-positive tests, with positive rates of 29% for Rarecyte, 57% for FAST, and 79% for the combination. We also assessed CTC phenotype: 56.6% of the CTCs were cytokeratin (CK)+/epithelial cell adhesion molecule (EpCAM)-, 3.1% were CK-/EpCAM+, and 40.3% were CK+/EPCAM+. The captured CTCs diameter ranged from 5.2 to 16.9 µm. The mean CTC size from the FAST waste chamber was significantly smaller. The diameters for each of the phenotypic groups were significantly different.

CONCLUSIONS

These data highlight disparities in the positive rates and enumerated CTC numbers detected by the two techniques. Notably, the combination of the two technologies resulted in the highest CTC-capture rates. Smaller CTCs were more likely to be missed by the FAST as they passed through the filter system. Sizes of CTCs varied with different cell surface marker phenotypes.

CTC analysis: an update on technological progress

There is a growing need for a more accurate, real-time assessment of tumor status and the probability of metastasis, relapse, or response to treatment. Conventional means of assessment include imaging and tissue biopsies that can be highly invasive, may not provide complete information of the disease's heterogeneity, and not ideal for repeat analysis. Therefore, a less-invasive means of acquiring similar information at greater time points is necessary. Liquid biopsies are samples of a patients' peripheral blood and hold potential of addressing these criteria. Ongoing research has revealed that a tumor can release circulating cells, genetic materials (DNA or RNA), and exosomes into circulation. These potential biomarkers can be captured in a liquid biopsy and analyzed to determine disease status. To achieve these goals, numerous technologies have been developed. In this review, we discuss both prominent and newly developed technologies for circulating tumor cell capture and analysis and their clinical impact.

EpCAMlow Circulating Tumor Cells: Gold in the Waste

The CellSearch® system which is still considered the gold standard for the enumeration of circulating tumor cells (CTC) utilizes antibodies against the epithelial cell adhesion molecule (EpCAM) for CTC enrichment. Recently, CTC discarded by the CellSearch® system due to their low EpCAM expression have been isolated and analyzed. We here sought to discuss technical and biological issues concerning the isolation and characterization of EpCAM^low CTC, highlighting the enormous potential of this subpopulation discarded by CellSearch®, which might instead reveal an unexpected clinical significance in tumor types where CTC enumeration has never been validated for prognostic and predictive purpose.

The current role of circulating biomarkers in non-muscle invasive bladder cancer

Non-muscle invasive bladder cancer (NMIBC) is characterized by its high rate of disease recurrence and relevant disease progression rates. Up to today clinical models are insufficiently predicting outcomes for reliable patient counseling and treatment decision-making. This particularly is a serious problem in patients with high-risk NMIBC who are at high risk for failure of local treatment and thus candidates for early radical cystectomy or even systemic (neoadjuvant) chemotherapy. Next to its clinical variability, bladder cancer is genetically a highly heterogeneous disease. There is an essential need of biomarkers for improving clinical staging, real-time monitoring of disease with or without active treatment, as well as improved outcome prognostication. Liquid biopsies of circulating biomarkers in the blood and urine are promising non-invasive diagnostics that hold the potential facilitating these needs. In this review we report the latest data and evidence on cell-free circulating tumor desoxyribonucleic acid (ctDNA) and circulating tumor cells (CTC) in NMIBC. We summarize their current status in clinical diagnostics, discuss limitations and address future needs.

Liquid Biopsy Biomarkers in Bladder Cancer: A Current Need for Patient Diagnosis and Monitoring

Bladder Cancer (BC) represents a clinical and social challenge due to its high incidence and recurrence rates, as well as the limited advances in effective disease management. Currently, a combination of cytology and cystoscopy is the routinely used methodology for diagnosis, prognosis and disease surveillance. However, both the poor sensitivity of cytology tests as well as the high invasiveness and big variation in tumour stage and grade interpretation using cystoscopy, emphasizes the urgent need for improvements in BC clinical guidance. Liquid biopsy represents a new non-invasive approach that has been extensively studied over the last decade and holds great promise. Even though its clinical use is still compromised, multiple studies have recently focused on the potential application of biomarkers in liquid biopsies for BC, including circulating tumour cells and DNA, RNAs, proteins and peptides, metabolites and extracellular vesicles. In this review, we summarize the present knowledge on the different types of biomarkers, their potential use in liquid biopsy and clinical applications in BC.