Epithelial‑mesenchymal transition phenotype of circulating tumor cells is associated with distant metastasis in patients with NSCLC

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.

Astragalus membranaceus: A Review of Its Antitumor Effects on Non-Small Cell Lung Cancer

The rising global morbidity and mortality rates of non-small cell lung cancer (NSCLC) underscore the urgent need for more effective treatments. Current therapeutic modalities-including surgery, radiotherapy, chemotherapy, and targeted therapy-face several limitations. Recently, Astragalus membranaceus, a traditional Chinese medicine (TCM), has captured significant attention due to its broad pharmacological properties, such as immune regulation, anti-inflammatory effects, and the modulation of reactive oxygen species (ROS) and enzyme activities. This review delivers a comprehensive summary of the most recent advancements and ongoing applications of Astragalus membranaceus in NSCLC treatment, underlining its potential for integration into existing treatment protocols. It also highlights essential areas for future research, including the elucidation of its molecular mechanisms, optimization of dosage and administration, and evaluation of its efficacy and safety alongside standard therapies, all of which could potentially improve therapeutic outcomes for NSCLC patients.

Detection of PD‑L1 expression and epithelial‑mesenchymal transition of circulating tumor cells in non‑small cell lung cancer

The present study aimed to assess the roles of peripheral circulating tumor cell (CTC) count, CTC subtypes and programmed death ligand 1 (PD-L1) expression in the clinical staging and prognosis of patients with non-small cell lung cancer (NSCLC). A total of 100 patients with NSCLC with available tumor tissues were enrolled in the present study, and 7.5 ml peripheral blood was collected. Patients were divided into PD-L1-positive and PD-L1-negative groups according to PD-L1 immunohistochemical staining. Peripheral blood samples from both groups were analyzed to determine the CTC count, epithelial-type CTCs (E-CTCs), mesenchymal-type CTCs (M-CTCs) and PD-L1 expression. Clinical data were collected, and patients were followed up for a maximum of 36 months, with patient death as the endpoint event. Patients with PD-L1-positive tumors had a worse prognosis compared with those with PD-L1-negative tumors (P=0.045). The PD-L1-positive group exhibited significantly higher numbers of CTCs and M-CTCs compared with the PD-L1-negative group (P≤0.05). However, the number of E-CTCs did not differ significantly between the two groups (P>0.05). PD-L1-positive patients with higher CTC and M-CTC counts had relatively poorer prognoses (P≤0.05), while the number of E-CTCs had no significant effect on prognosis (P>0.05). Compared with the early-stage NSCLC group, the late-stage NSCLC group exhibited a significant increase in the CTC count (P≤0.05), while E-CTC and M-CTC counts did not significantly differ between the two groups (P>0.05). The PD-L1-positive group exhibited a significant increase in the number of PD-L1+ CTCs and PD-L1+ M-CTCs compared with the PD-L1-negative group (P≤0.05), while PD-L1+ E-CTC counts did not differ significantly between the two groups (P>0.05). The PD-L1-positive patients with a higher number of PD-L1+ CTCs and PD-L1+ M-CTCs had relatively poorer prognoses (P≤0.05), while the PD-L1+ E-CTC count had no significant effect on prognosis (P>0.05). Compared with the early-stage NSCLC group, the late-stage NSCLC group exhibited a significant increase in the number of PD-L1+ CTCs and PD-L1+ M-CTCs (P≤0.05), while PD-L1+ E-CTC counts did not significantly differ between the two groups (P>0.05). Based on univariate and multivariate analyses, the number of PD-L1+ M-CTCs was identified as an independent prognostic factor for NSCLC. In conclusion, the presence of CTCs in peripheral blood, particularly PD-L1+ M-CTC subtype, indicated poorer clinical staging and prognosis in patients with NSCLC. These findings suggested that CTCs, specifically the PD-L1+ M-CTC subtype, could serve as a monitoring indicator for the clinical staging and prognosis of patients with NSCLC.

Powering single-cell genomics to unravel circulating tumour cell subpopulations in non-small cell lung cancer patients

BACKGROUND

Circulating tumour cells (CTCs) are attractive "liquid biopsy" candidates that could provide insights into the different phenotypes of tumours present within a patient. The epithelial-to-mesenchymal transition (EMT) of CTCs is considered a critical step in tumour metastasis; however, it may confound traditional epithelial feature-based CTC isolation and detection. We applied single-cell copy number alteration (CNA) analysis for the identification of genomic alterations to confirm the neoplastic nature of circulating cells with only mesenchymal phenotypes.

METHODS

We isolated CTCs from blood samples collected from 46 NSCLC patients using the Parsortix system. Enriched cells were subjected to immunofluorescent staining for CTC identification using a multi-marker panel comprising both epithelial and mesenchymal markers. A subset of isolated CTCs was subjected to whole genome amplification (WGA) and low-pass whole-genome sequencing (LP-WGS) for the analysis of copy number alterations (CNAs).

RESULTS

CTCs were detected in 16/46 (34.8%) patients, inclusive of CK⁺/EpCAM⁺ CTCs (3/46, 6.5%) and Vim⁺ CTCs (13/46, 28.3%). Clusters of Vim⁺ cells were detected in 8 samples, which constitutes 50% of the total number of NSCLC patients with CTCs. No patients had detectable hybrid CK⁺/EpCAM⁺/Vim⁺ cells. All of the tested CK⁺/EpCAM⁺ CTCs and 7/8 Vim⁺ CTCs or CTC clusters carried CNAs confirming their neoplastic nature. Notably, the Vim⁺ cluster with no CNAs was characterised by spindle morphology and, therefore, defined as normal mesenchymal circulating cells.

CONCLUSION

Our results revealed that CK-negative, vimentin-expressing cells represent a large proportion of CTCs detected in NSCLC patients, which are likely missed by standard epithelial-marker-dependent CTC categorisation.

Effect of Osimertinib on CTCs and ctDNA in EGFR Mutant Non-Small Cell Lung Cancer Patients: The Prognostic Relevance of Liquid Biopsy

Simple Summary

Osimertinib has become the standard of care for the first-line treatment of EGFR-mutant NSCLC patients. The aim of this current translational research study was to assess the clinical relevance of liquid biopsy in 47 patients receiving osimertinib. Effects on circulating tumor cells (CTCs) and plasma-DNA (ctDNA) were investigated before, after one treatment cycle, and at the end of treatment. ctDNA and CTCs decreased after one treatment cycle, but increased at the end of treatment. The detection of ctDNA before and after one treatment cycle was associated with shorter progression-free and overall survivals (PFS and OS), whereas ctDNA clearance after one treatment cycle resulted in a significantly longer PFS and OS. ctDNA at baseline emerged as an independent predictor of shorter PFS. Thus, changes in liquid biopsy status (CTCs, ctDNA) during osimertinib treatment can be used as a tool for treatment efficacy.

Abstract

Introduction: Liquid biopsy is a useful tool for monitoring treatment outcome in solid tumors, including lung cancer. The relevance of monitoring CTCs and plasma ctDNA as predictors of clinical outcome was assessed in EGFR-mutant NSCLC patients treated with osimertinib. Methods: Forty-seven EGFR-mutant NSCLC patients who had progressed on prior first- or second-generation EGFR inhibitors were enrolled in the study and treated with osimertinib, irrespective of the presence of the T790M mutation in the primary tumor or the plasma. Peripheral blood was collected at baseline (n = 47), post-Cycle 1 (n = 47), and at the end of treatment (EOT; n = 39). CTCs were evaluated in 32 patients at the same time points (n = 32, n = 27, and n = 21, respectively) and phenotypic characterization was performed using triple immunofluorescence staining (CK/VIM/CD45). Results: Osimertinib resulted in an ORR of 34% (2 CR) and a DCR of 76.6%. The median PFS and OS values were 7.5 (range, 0.8–52.8) and 15.1 (range, 2.1–52.8) months, respectively. ctDNA was detected in 61.7%, 27.7%, and 61.5% of patients at baseline, post-Cycle 1, and EOT, respectively. CTCs (CK+/CD45-) were detected in 68.8%, 48.1%, and 61.9% of patients at the three time points, respectively. CTCs expressing both epithelial and mesenchymal markers (CK+/VIM+/CD45-) were detected in 56.3% and 29.6% of patients at baseline and post-Cycle 1, respectively. The detection of ctDNA at baseline and post-Cycle 1 was associated with shorter PFS and OS, whereas the ctDNA clearance post-Cycle 1 resulted in a significantly longer PFS and OS. Multivariate analysis revealed that male sex and the detection of ctDNA at baseline were independent predictors of shorter PFS (HR: 2.6, 95% C.I.: 1.2–5.5, p = 0.015 and HR: 3.0, 95% C.I.: 1.3–6.9; p = 0.009, respectively). Conclusions: The decrease in both CTCs and ctDNA occurring early during osimertinib treatment is predictive of better outcome, implying that liquid biopsy monitoring may be a valuable tool for the assessment of treatment efficacy.

Leukapheresis increases circulating tumour cell yield in non-small cell lung cancer, counts related to tumour response and survival

BACKGROUND

Circulating tumour cells (CTCs) can be used to monitor cancer longitudinally, but their use in non-small cell lung cancer (NSCLC) is limited due to low numbers in the peripheral blood. Through diagnostic leukapheresis (DLA) CTCs can be obtained from larger blood volumes.

METHODS

Patients with all stages of NSCLC were selected. One total body blood volume was screened by DLA before and after treatment. Peripheral blood was drawn pre- and post DLA for CTC enumeration by CellSearch. CTCs were detected in the DLA product (volume equalling 2 × 108 leucocytes) and after leucocyte depletion (RosetteSep, 9 mL DLA product). Single-cell, whole-genome sequencing was performed on isolated CTCs.

RESULTS

Fifty-six patients were included. Before treatment, CTCs were more often detected in DLA (32/55, 58%) than in the peripheral blood (pre-DLA: 18/55, 33%; post DLA: 13/55, 23%, both at p < 0.01). CTCs per 7.5 mL DLA product were median 9.2 times (interquartile range = 5.6-24.0) higher than CTCs in 7.5 mL blood. RosetteSEP did not significantly improve CTC detection (pretreatment: 34/55, 62%, post treatment: 16/34, 47%) and CTCs per mL even decreased compared to DLA (p = 0.04).. Patients with advanced-stage disease with DLA-CTC after treatment showed fewer tumour responses and shorter progression-free survival (PFS) than those without DLA-CTC (median PFS, 2.0 vs 12.0 months, p < 0.01). DLA-CTC persistence after treatment was independent of clinical factors associated with shorter PFS (hazard ratio (HR) = 5.8, 95% confidence interval (CI), 1.4-35.5, p = 0.02). All evaluable CTCs showed aneuploidy.

CONCLUSIONS

DLA detected nine times more CTCs than in the peripheral blood. The sustained presence of CTCs in DLA after treatment was associated with therapy failure and shortened PFS.

TRIAL REGISTRATION

The study was approved by the Medical Ethical Committee (NL55754.042.15) and was registered in the Dutch trial register (NL5423).

Detyrosinated α-Tubulin, Vimentin and PD-L1 in Circulating Tumor Cells (CTCs) Isolated from Non-Small Cell Lung Cancer (NSCLC) Patients

Upregulation of Vimentin (VIM), alpha-Tubulin (TUB) and Detyrosinated tubulin (GLU) in circulating tumor cells (CTCs) derived from breast cancer patients is related to poor prognosis. In the current study we evaluated for the first time, these cytoskeletal proteins in sixty Non-Small Cell Lung Cancer (NSCLC) patients’ CTCs (33 treatment-naïve and 27 pre-treated). Samples were isolated using the ISET platform and stained with a pancytokeratin (CK)/CD45/TUB, CK/GLU/VIM and CK/programmed death ligand 1 (PD-L1) combination of antibodies. Subsequently, slides were analyzed using confocal laser scanning microscopy. CTCs were detected in 86.7% of the patients. CTCs with TUB expression were identified in 65.4% (34/52) of the CK (+)-patients. GLU, VIM and PD-L1 were also evaluated. The frequency of the observed phenotypes was as follow: (CK+/GLU−/VIM−): 35.2%, (CK+/GLU+/VIM+): 63.0%, (CK+/GLU+/VIM−): 16.7%, (CK+/GLU−/VIM+): 72.2%, (CK+/PD-L1−): 75% and (CK+/PD-L1+): 55%. The OS was significantly decreased in patients with high GLU (3.8 vs. 7.9 months; p = 0.018) and/or high VIM (3.2 vs. 7.1 months; p = 0.029) expression in their CTCs. PD-L1 was also related to OS (3.4 vs. 7.21 months; p = 0.035). Moreover, TUB-high and TUB-low expression in CTCs inversely influenced patients’ OS as independent prognostic factors (p = 0.041 and p = 0.009). The current study revealed that TUB, GLU, VIM and PD-L1 were overexpressed in CTCs from NSCLC patients. Furthermore, the presence of GLU, VIM-positive and PD-L1 in CTCs is potentially related to patients’ outcomes.

Circulating tumor cells counts are associated with CD8+ T cell levels in programmed death-ligand 1-negative non-small cell lung cancer patients after radiotherapy: A retrospective study

This study aimed to explore the dynamics of circulating tumor cells (CTCs) and CD8+ T cells in stage II-III non-small cell lung cancer patients with CTCs in different programmed death-ligand 1 (PD-L1) status treated with radiotherapy and evaluate the correlation between CTCs and CD8+ T cells.This study was a retrospective study which reviewed 69 stage II-III non-small cell lung cancer patients underwent postoperative radiotherapy and peripheral blood tests of CTCs and T lymphocyte were available before radiation, 1 week after radiation and 1 month after radiation.In this study, 25 patients had PD-L1 positive CTCs and 44 patients had PD-L1 negative CTCs. The CTCs count was significantly decreased compared with baseline in patients with different PD-L1 status CTCs at 1 week and 1 month after radiotherapy. The proportion of CD8+ T cells was significantly increased at 1 month after radiotherapy compared with baseline in the total population (mean change, 7.24 ± 2.12; P < .05) and patients with PD-L1 negative CTCs (mean change, 7.17 ± 2.65; P < .05). One month after radiotherapy, the proportion of CD8+ T cells was negatively correlated with the CTCs count in the total population (r = -0.255, P = .034) and PD-L1 negative patients (r = -0.330, P = .029). In patients with PD-L1 negative CTCs, the CTCs count 1 week after radiotherapy (hazard ratio, 0.150 [95% confidence intervals., 0.027-0.840], P = .031) and the proportion of CD8+ T cells 1 month after radiotherapy (hazard ratio, 7.961 [95% confidence intervals, 1.028-61.68], P = .047) were independent prognostic factors for disease recurrence.After radiotherapy, only PD-L1-negative patients had a significant increase in the CD8+ T cell levels, while it was negatively correlated with CTCs count and was an independent prognostic factors of disease recurrence.

Epithelial circulating tumor cells with a heterogeneous phenotype are associated with metastasis in NSCLC

Objectives

To analyze the clinical relevance of heterogeneous phenotypes of peripheral circulating tumor cells (CTCs) in non-small cell lung cancer (NSCLC).

Materials and Methods

CTCs in 5 mL venous blood were enriched using the Canpatrol™ CTC technique in 82 NSCLC patients. And then, CTCs were subjected to RNA in situ hybridization with a combination of epithelial (EpCAM and CK8/18/19) and mesenchymal (vimentin and TWIST1) markers.

Results

According to the fluorescent dots, CTCs were classified into three groups, including epithelial CTCs (E-CTC), hybrid epithelial/mesenchymal phenotypes (E/M-CTCs) and mesenchymal CTCs (M-CTCs). In 82 NSCLC cohort, only 2 patients didn’t detect CTCs, the overall CTCs detection rate was 97.5% (80/82). For 60 treatment naïve NSCLC, only one patient didn’t detect CTCs. The median number of total CTCs, hybrid E/M phenotype CTCs, E-CTCs and M-CTCs per 5 mL blood was 22 (range 1–90), 13 (range 0–83), 1 (range 0–17 and 0–47), respectively. Hybrid E/M CTCs, especially the e = m-CTCs, significantly differed between patients with and without distant metastasis. M-CTCs in advanced NSCLC patients were significantly more than the numbers observed in early stage patients. Patients with pure hybrid E/M-CTCs showed a lower proportion in distant metastasis positive cohort compared to negative ones (7% vs 22%), while patients with E + E/M CTCs (20% vs 9%) and E/M + M CTCs (33% vs 20%) showed a higher proportion. CTCs dynamic changes after treatment in 12 advanced NSCLC patients suggested that hybrid E/M-CTCs were related to the primary tumor size at baseline, while M-CTCs may suggest the progression of NSCLC.

Conclusion

We concluded that E-CTCs with a hybrid E/M phenotype are associated to metastasis in therapy-naïve NSCLC patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-021-03681-9.

Clinical Relevance of Mesenchymal- and Stem-Associated Phenotypes in Circulating Tumor Cells Isolated from Lung Cancer Patients

Simple Summary

Lung cancer is the most frequent malignancy in the world. Most lung cancer patients are diagnosed at an advanced stage. To make matters worse, the survival of patients is very poor. Circulating tumor cells (CTCs), albeit rare, have been portrayed as essential players in the progression of lung cancer. It is definitely not easy being a CTC. First, they escape from the primary tumor, then they travel in the bloodstream, have to survive really harsh conditions, and finally, they form metastases. The adoption of epithelial-to-mesenchymal transition as well as cancer stem cell features has been suggested to allow CTCs to survive and metastasize. This review will focus on how these features can be used to estimate the prognosis of lung cancer patients.

Abstract

Lung cancer is the leading cause of cancer-related mortality globally. Among the types of lung cancer, non-small-cell lung cancer (NSCLC) is more common, while small-cell lung cancer (SCLC) is less frequent yet more aggressive. Circulating tumor cells (CTCs), albeit rare, have been portrayed as essential players in the progression of lung cancer. CTCs are considered to adopt an epithelial-to-mesenchymal transition (EMT) phenotype and characteristics of cancer stem cells (CSCs). This EMT (or partial) phenotype affords these cells the ability to escape from the primary tumor, travel into the bloodstream, and survive extremely adverse conditions, before colonizing distant foci. Acquisition of CSC features, such as self-renewal, differentiation, and migratory potential, further reflect CTCs’ invasive potential. CSCs have been identified in lung cancer, and expression of EMT markers has previously been correlated with poor clinical outcomes. Thus far, a vast majority of studies have concentrated on CTC detection and enumeration as a prognostic tools of patients’ survival or for monitoring treatment efficacy. In this review, we highlight EMT and CSC markers in CTCs and focus on the clinical significance of these phenotypes in the progression of both non-small- and small-cell lung cancer.

Evaluation of Monocarboxylate Transporter 4 (MCT4) Expression and Its Prognostic Significance in Circulating Tumor Cells From Patients With Early Stage Non-Small-Cell Lung Cancer

Purpose: Monocarboxylate transporter 4 (MCT4) can influence the amount of lactate in the tumor microenvironment and further control cancer cell proliferation, migration, and angiogenesis. We investigated for the first time the expression of MCT4 in circulating tumor cells (CTCs) derived from early stage Non-Small Cell Lung Cancer patients (NSCLC) and whether this is associated with clinical outcome.

Experimental Design: A highly sensitive RT-qPCR assay for quantification of MCT4 transcripts was developed and validated and applied to study MCT4 expression in CTC isolated through the Parsortix size-dependent microfluidic device from 53 and 9 peripheral blood (PB) samples of NSCLC patients at baseline (pre-surgery) and at relapse, respectively, as well as the “background noise” was evaluated using peripheral blood samples from 10 healthy donors (HD) in exactly the same way as patients.

Results:MCT4 was differentially expressed between HD and NSCLC patients. Overexpression of MCT4 was detected in 14/53 (26.4%) and 3/9 (33.3%) patients at baseline and at progression disease (PD), respectively. The expression levels of MCT4 was found to increase in CTCs at the time of relapse. Kaplan-Meier analysis showed that the overexpression of MCT4 was significantly (P = 0.045) associated with progression-free survival (median: 12.5 months, range 5–31 months).

Conclusion:MCT4 overexpression was observed at a high frequency in CTCs from early NSCLC patients supporting its role in metastatic process. MCT4 investigated as clinically relevant tumor biomarker characterizing tumor aggressiveness and its potential value as target for cancer therapy. We are totally convinced that MCT4 overexpression in CTCs merits further evaluation as a non-invasive circulating tumor biomarker in a large and well-defined cohort of patients with NSCLC.

Mesenchymal Characteristics and Predictive Biomarkers on Circulating Tumor Cells for Therapeutic Strategy

Metastasis-related events are the primary cause of cancer-related deaths, and circulating tumor cells (CTCs) have a pivotal role in metastatic relapse. CTCs include a variety of subtypes with different functional characteristics. Interestingly, the epithelial-mesenchymal transition (EMT) markers expressed in CTCs are strongly associated with poor clinical outcome and related to the acquisition of circulating tumor stem cell (CTSC) features. Recent studies have revealed the existence of CTC clusters, also called circulating tumor microemboli (CTM), which have a high metastatic potential. In this review, we present current opinions regarding the clinical significance of CTCs and CTM with a mesenchymal phenotype as clinical surrogate markers, and we summarize the therapeutic strategy according to phenotype characterization of CTCs in various types of cancers for future precision medicine.

Circulating tumor cells as Trojan Horse for understanding, preventing, and treating cancer: a critical appraisal

Circulating tumor cells (CTCs) are regarded as harbingers of metastases. Their ability to predict response to therapy, relapse, and resistance to treatment has proposed their value as putative diagnostic and prognostic indicators. CTCs represent one of the zeniths of cancer evolution in terms of cell survival; however, the triggers of CTC generation, the identification of potentially metastatic CTCs, and the mechanisms contributing to their heterogeneity and aggressiveness represent issues not yet fully deciphered. Thus, prior to enabling liquid biopsy applications to reach clinical prime time, understanding how the above mechanistic information can be applied to improve treatment decisions is a key challenge. Here, we provide our perspective on how CTCs can provide mechanistic insights into tumor pathogenesis, as well as on CTC clinical value. In doing so, we aim to (a) describe how CTCs disseminate from the primary tumor, and their link to epithelial-mesenchymal transition (EMT); (b) trace the route of CTCs through the circulation, focusing on tumor self-seeding and the possibility of tertiary metastasis; (c) describe possible mechanisms underlying the enhanced metastatic potential of CTCs; (d) discuss how CTC could provide further information on the tissue of origin, especially in cancer of unknown primary origin. We also provide a comprehensive review of meta-analyses assessing the prognostic significance of CTCs, to highlight the emerging role of CTCs in clinical oncology. We also explore how cell-free circulating tumor DNA (ctDNA) analysis, using a combination of genomic and phylogenetic analysis, can offer insights into CTC biology, including our understanding of CTC heterogeneity and tumor evolution. Last, we discuss emerging technologies, such as high-throughput quantitative imaging, radiogenomics, machine learning approaches, and the emerging breath biopsy. These technologies could compliment CTC and ctDNA analyses, and they collectively represent major future steps in cancer detection, monitoring, and management.

EMT-Associated Heterogeneity in Circulating Tumor Cells: Sticky Friends on the Road to Metastasis

Epithelial-mesenchymal transitions (EMTs) generate hybrid phenotypes with an enhanced ability to adapt to diverse microenvironments encountered during the metastatic spread. Accordingly, EMTs play a crucial role in the biology of circulating tumor cells (CTCs) and contribute to their heterogeneity. Here, we review major EMT-driven properties that may help hybrid Epithelial/Mesenchymal CTCs to survive in the bloodstream and accomplish early phases of metastatic colonization. We then discuss how interrogating EMT in CTCs as a companion biomarker could help refine cancer patient management, further supporting the relevance of CTCs in personalized medicine.

Clinical significance of circulating tumor cells in patients with locally advanced head and neck squamous cell carcinoma

The present study aimed to investigate the clinical relevance of circulating tumor cells (CTCs) in patients with locally advanced head and neck squamous cell carcinoma (LA‑HNSCC), particularly in patients with nasopharyngeal and hypopharyngeal squamous cell carcinoma. CTCs were isolated using negative immunomagnetic bead enrichment and were identified by fluorescence in situ hybridization. Youden's index and the receiver operating characteristic (ROC) curve were used to select the optimal CTC baseline value. χ2 test or Fisher's test were used to determine the association between CTC counts and clinical parameters, curative effects and prognosis. The Kaplan‑Meier estimator was used to analyze overall survival (OS) and progression‑free survival (PFS). In the present study, 356 peripheral blood samples (178 pretreatment samples and 178 post‑treatment samples) from 178 patients were examined. The results revealed that the pretreatment CTC detection rate was 73.8%. The minimum, maximum and median CTC counts were 1, 22 and 2/3.2 ml, respectively. The number of polyploid CTCs was associated with distant metastasis (P=0.026). In addition, patients with undetectable CTCs, and decreasing or negative CTCs post‑treatment tended to have a good prognosis (P<0.05). For nasopharyngeal squamous cell carcinoma, the PFS of patients with increased CTCs and CTCs ≥2/3.2 ml after treatment was significantly lower (P<0.05). For hypopharyngeal squamous cell carcinoma, it was suggested that CTCs with a cutoff value of 3 may be used to evaluate PFS and OS before and after treatment. In conclusion, CTCs may be used to monitor disease progression and the response to chemoradiotherapy for patients with LA‑HNSCC. Furthermore, CTCs are a better predictor of the prognosis of hypopharyngeal squamous cell carcinoma than that of nasopharyngeal squamous cell carcinoma.

Circulating Tumor Cell Detection in Lung Cancer: But to What End?

The understanding of the natural history and biology of lung cancer has been enhanced by studies into circulating tumor cells (CTCs). Fundamental and translational research, as well as clinical trials in the characterization and behavior of these cells, have constantly contributed to improving understanding within the domain of thoracic oncology. However, the use of these CTCs as prognostic and predictive biomarkers has not been adopted to the same extent as circulating free DNA (cf-DNA) in plasma, in the daily practice of thoracic oncologists. However, recent technological advances have firmly put the detection and characterization of CTCs in thoracic oncology back on the agenda, and have opened up perspectives for their routine clinical use. This review discusses the major advances of using CTCs in the domain of thoracic oncology, as well as the envisaged short- and long-term prospects.