The prognostic role of circulating tumor cells in lung cancer

Progress and application of circulating tumor cells in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) has the highest morbidity and mortality worldwide among malignant tumors. NSCLC is a great threat to health and well-being. Biopsy is the gold standard to diagnose lung cancer, but traditional biopsy methods cannot fully reflect the true condition of tumors. There is growing evidence that a single-point biopsy fails to reveal the complete landscape of the tumor due to intratumor heterogeneity, but it is impractical to complete multiple biopsies that are separated both spatially and temporally. Liquid biopsy heralds that a new era is coming. Circulating tumor cells (CTCs) are tumor cells that circulate in the peripheral blood after being shed from primary or metastatic tumors. CTCs constitute a considerable portion of a liquid biopsy, which contributes to the diagnosis, assessment of prognosis, and therapy of NSCLC. Herein, this review discusses the technologies for detection and enrichment of CTCs as well as clinical applications involving CTCs.

Promising Role of Circulating Tumor Cells in the Management of SCLC

Small cell lung cancer is an aggressive disease for which few therapeutic options are currently available. Although patients initially respond to therapy, they rapidly relapse. Up to today, no biomarkers for guiding treatment of SCLC patients have been identified. SCLC patients rarely undergo surgery and often the available tissue samples are inadequate for biomarker analysis. Circulating tumor cells (CTCs) are rare cells in the peripheral blood that might be used as surrogates of tissue samples. Different methodological approaches have been developed for studies of CTCs in SCLC. In addition to CTC count, which might provide prognostic and predictive information, genomic and transcriptomic analyses allow the characterization of molecular profiles of CTCs and permit the study of tumor heterogeneity. The employment of CTC-derived xenografts offers complementary information to genomic analyses and CTC enumeration about the mechanisms involved in the sensitivity/resistance to treatments. Using these approaches, CTC analysis is providing relevant information on SCLC biology that might aid in the development of personalized therapeutic strategies for SCLC patients.

Liquid Biopsy Strategies to Distinguish Progression from Pseudoprogression and Radiation Necrosis in Glioblastomas

Liquid biopsy for the detection and monitoring of central nervous system tumors is of significant clinical interest. At initial diagnosis, the majority of patients with central nervous system tumors undergo magnetic resonance imaging (MRI), followed by invasive brain biopsy to determine the molecular diagnosis of the WHO 2016 classification paradigm. Despite the importance of MRI for long-term treatment monitoring, in the majority of patients who receive chemoradiation therapy for glioblastoma, it can be challenging to distinguish between radiation treatment effects including pseudoprogression, radiation necrosis, and recurrent/progressive disease based on imaging alone. Tissue biopsy-based monitoring is high risk and not always feasible. However, distinguishing these entities is of critical importance for the management of patients and can significantly affect survival. Liquid biopsy strategies including circulating tumor cells, circulating free DNA, and extracellular vesicles have the potential to afford significant useful molecular information at both the stage of diagnosis and monitoring for these tumors. Here, current liquid biopsy-based approaches in the context of tumor monitoring to differentiate progressive disease from pseudoprogression and radiation necrosis are reviewed.

Blood-based Biomarkers for Early Diagnosis of Lung Cancer: A Review Article

Lung cancer is the severe leading cause of cancer-related mortality worldwide. Early detection of lung cancer can significantly increase their survival rate. However, conventional lung cancer screening methods such as sputum cytology, chest X-rays, low-dose computed tomography, positron emission tomography, and magnetic resonance imaging, are radiational, and also expensive methods. Similarly, lung tumor tissue as invasive and difficult to obtain and potentially risky procedures, there is the immediate need of non-invasive, novel sensitive and reliable blood-based tumor markers which now has become an important area on research. This review will mainly focus on recently identified circulating biomarkers: circulating tumor cells, circulating tumor deoxyribonucleic acid, tumor-derived exosomes, circulating ribonucleic acid and micro ribonucleic acid, and tumor-educated platelets which may enable earlier diagnosis of lung cancer and their application in clinical practices.

Circulating tumor cells as a new predictive and prognostic factor in patients with small cell lung cancer

Background: Small cell lung cancer (SCLC) is the most malignant type of lung cancer characterized by rapid progression, early metastasis and recurrence. In recent years, circulating tumor cells (CTCs) were found to play an important role in tumor invasion, metastasis, recurrence and prognosis.

Methods: CTCs were detected in 138 patients with newly diagnosed SCLC from January 2012 to December 2018. Nomogram prediction models were constructed based on prognostic factors screened by multivariate Cox regression analysis and the risk stratification of SCLC patients were performed on basis of nomogram points. A total of 108 patients from January 2012 to December 2016 were assigned to a training group, and 30 patients from January 2017 to December 2018 were included into the validation group for nomogram analysis. This study was approved by ethics committee of Guangzhou First People's Hospital and all subjects provided informed consent.

Results: The number of CTCs was associated with age, lymph node metastasis (N), distant metastasis (M), TNM staging, and NSE. The high number of CTC predicted adverse prognosis, and the AUC of time-dependent ROC curve was all high than 0.5. In the training group, after multivariate COX regression screening, the factors in the median survival time (MST) and overall survival (OS) nomogram prediction models were age, TNM, CTC, NSE and treatment mode. The C-index of the nomograms in internal validation for MST and OS was 0.813 and in external validation for MST and OS were 0.885. The AUC of ROC curves for nomogram were high than 0.5. Finally, risk stratification could be effectively performed on the basis of nomogram points.

Conclusions: CTC can be served as a predictive and prognostic factor for SCLC, and the nomogram models constructed by CTC and multiple clinical parameters can comprehensively predict the prognosis of SCLC patients and perform risk stratification.

Identification of plasma exosomes long non-coding RNA HAGLR and circulating tumor cells as potential prognosis biomarkers in non-small cell lung cancer

Background

The main purpose of this study was to identify the correlation between the expression of long non-coding RNA (lncRNA) HAGLR in plasma exosomes and the detection rate of circulating tumor cells (CTCs) in patients with non-small cell lung cancer (NSCLC).

Methods

LncRNA HAGLR expression was detected in plasma exosomes of 40 patients with NSCLC and 8 healthy subjects using qRT-PCR. CTCs were enriched and separated using CTC-BIOPSY^® abnormal cell separator. The correlations between lncRNA HAGLR expression in plasma exosomes and CTCs of patients with NSCLC and clinical pathological parameters were also analyzed. Bioinformatics analyses indicated HAGLR was evidently down-regulated in NSCLC tissues when compared to normal controls. The relationship between differential expression of HAGLR with different stages of NSCLC and clinical prognosis were elucidated using corresponding statistical methods.

Results

HAGLR was significantly decreased in NSCLC, and there was obvious correlation with overall survival (P<0.05). CTCs were detected in peripheral blood of patients with NSCLC with the positive rate of 70.0%. In lung squamous cell carcinoma (LUSC), compared with the high expression group of HAGLR, the low expression group had a better overall survival (P<0.05). At the same time, the high expression of HAGLR was positively correlated with the high detection rate of CTCs (P<0.05), suggesting that the disease may have a later tumor stage, and poor prognosis.

Conclusions

lncRNA HAGLR and CTCs could be used as potential biomarkers for NSCLC metastasis risk prediction.

The potential of monitoring treatment response in non-small cell lung cancer using circulating tumour cells

Introduction: Circulating tumor cell (CTC) counts represent an attractive strategy for monitoring response to therapy in patients with advanced non-small cell lung cancer (NSCLC). Changes in the CTCs number during the treatment have been proposed as a predictive biomarker of response to both chemotherapy and targeted therapies. Profiling of CTCs might also allow the assessment of the dynamics of predictive biomarkers such as EGFR, ALK, ROS1, and PD-L1, and provide relevant information in patients progressing on treatment with targeted agents including immunotherapeutics. Areas covered: A search of peer-reviewed literature in bibliographic databases was undertaken to discuss studies on CTCs and their predictive role in NSCLC. Expert opinion: To date, some challenges limit the clinical utility of CTCs in monitoring the response to treatment in NSCLC. The standardization of techniques for CTCs isolation and characterization and their validation on larger cohorts of patients might help to translate CTCs analysis in the clinic. However, studies on CTCs can provide information on molecular mechanisms involved in NSCLC progression and in the acquired resistance to treatments.

Is the Blood an Alternative for Programmed Cell Death Ligand 1 Assessment in Non-Small Cell Lung Cancer?

Anti-programmed cell death (PD)-1/PD-ligand 1 (L1) therapies have significantly improved the outcomes for non-small cell lung cancer (NSCLC) patients in recent years. These therapies work by reactivating the immune system and enabling it to target cancer cells once more. There is a general agreement that expression of PD-L1 on tumour cells predicts the therapeutic response to PD-1/PD-L1 inhibitors in NSCLC. Hence, immunohistochemical staining of tumour tissue biopsies from NSCLC patients with PD-L1 antibodies is the current standard used to aid selection of patients for treatment with anti-PD-1 as first line therapy. However, issues of small tissue samples, tissue heterogeneity, the emergence of new metastatic sites, and dynamic changes in the expression of PD-L1 may influence PD-L1 status during disease evolution. Re-biopsy would expose patients to the risk of complications and tardy results. Analysis of PD-L1 expression on circulating tumour cells (CTCs) may provide an accessible and non-invasive means to select patients for anti-PD-1 therapies. Additionally, CTCs could potentially provide a useful biomarker in their own right. Several published studies have assessed PD-L1 expression on CTCs from NSCLC patients. Overall, analysis of PD-L1 on CTCs is feasible and could be detected prior to and after frontline therapy. However, there is no evidence on whether PD-L1 expression on CTCs could predict the response to anti-PD-1/PD-L1 treatment. This review examines the challenges that need to be addressed to demonstrate the clinical validity of PD-L1 analysis in CTCs as a biomarker capable of predicting the response to immune checkpoint blockade.

Liquid biopsy of cancer: a multimodal diagnostic tool in clinical oncology

Over the last decades, the concept of precision medicine has dramatically renewed the field of medical oncology; the introduction of patient-tailored therapies has significantly improved all measurable outcomes. Liquid biopsy is a revolutionary technique that is opening previously unexpected perspectives. It consists of the detection and isolation of circulating tumor cells, circulating tumor DNA and exosomes, as a source of genomic and proteomic information in patients with cancer. Many technical hurdles have been resolved thanks to newly developed techniques and next-generation sequencing analyses, allowing a broad application of liquid biopsy in a wide range of settings. Initially correlated to prognosis, liquid biopsy data are now being studied for cancer diagnosis, hopefully including screenings, and most importantly for the prediction of response or resistance to given treatments. In particular, the identification of specific mutations in target genes can aid in therapeutic decisions, both in the appropriateness of treatment and in the advanced identification of secondary resistance, aiming to early diagnose disease progression. Still application is far from reality but ongoing research is leading the way to a new era in oncology. This review summarizes the main techniques and applications of liquid biopsy in cancer.

Adaptive metabolic pattern biomarker for disease monitoring and staging of lung cancer with liquid biopsy

In this manuscript, we demonstrate the applicability of a metabolic liquid biopsy for the monitoring and staging of patients with lung cancer. This method provides an unbiased detection strategy to establish a more precise correlation between CTC quantification and the actual burden of disease, therefore improving the accuracy of staging based on current imaging techniques. Also, by applying statistical analysis techniques and probabilistic models to the metabolic status and distribution of peripheral blood mononuclear cell (PBMC) populations "perturbed" by the presence of CTCs, a new category of adaptive metabolic pattern biomarker (AMPB) is described and unambiguously correlated to the different clinical stages of the patients. In fact, this strategy allows for classification of different categories of disease within a single stage (stage IV) before computed tomography (CT) and positron emission tomography (PET) scans and with lower uncertainty.

The liquid biopsy in the management of colorectal cancer patients: Current applications and future scenarios

The term liquid biopsy refers to the analysis of biomarkers in any body fluid, including blood, urine and cerebrospinal fluid. In cancer, liquid biopsy testing allows the analysis of tumor-derived DNA, RNA, miRNA and proteins that can be either cell-free or contained in circulating tumor cells (CTC), extracellular vesicles (EVs) or platelets. A number of studies suggest that liquid biopsy testing could have a relevant role in the management of colorectal cancer (CRC) patients at different stages of the disease. Analysis of cell-free DNA (cfDNA), CTC and/or miRNA can provide relevant information for the early diagnosis of CRC and the identification of minimal residual disease and, more generally, the evaluation of the risk of recurrence in early CRC patients. In addition, liquid biopsy testing might allow the assessment of prognostic and predictive biomarkers in metastatic CRC patients, and the monitoring of the response to treatment and of the clonal evolution of the disease. While a number of elegant studies have shown the potential of liquid biopsy in CRC, the possibility to use this approach in the daily clinical practice is still limited. The use of non-standardized methods, the small cohorts of patients analyzed, the lack of demonstration of a clear clinical benefit are the main limitations of the studies with liquid biopsy in CRC reported up to now. The potential of this approach and the steps that need still to be taken to translate these preliminary findings in the clinic are discussed in this review.

Associations between the Epithelial-Mesenchymal Transition Phenotypes of Circulating Tumor Cells and the Clinicopathological Features of Patients with Colorectal Cancer

In this study, we identified CTCs using the previously reported CanPatrol CTC enrichment technique from peripheral blood samples of 126 patients with colorectal cancer (CRC) and found that CTCs could be classified into three subpopulations based on expression of epithelial cell adhesion molecule (EpCAM) (E-CTCs), the mesenchymal cell marker vimentin (M-CTCs), or both EpCAM and vimentin (biphenotypic E/M-CTCs). Circulating tumor microemboli (CTMs) were also identified in peripheral blood samples. Meanwhile, E-CTCs, M-CTCs, E/M-CTCs, and CTMs were detected in 76.98%, 42.06%, 56.35%, and 36.51% of the 126 patients, respectively. Interestingly, the presence of CTMs and each CTC subpopulation was significantly associated with blood lymphocyte counts and tumor-node-metastasis stage (P < 0.001). Lymphocyte counts and the neutrophil-to-lymphocyte ratio (NLR) in patients lacking CTCs were significantly different from those in patients testing positive for CTMs and each CTC subpopulation (P < 0.001). Our results indicate that tumor metastasis is more significantly associated with the presence of CTMs and M-CTCs than with other CTC subpopulations and suggest that EMT may be involved in CTC evasion of lymphocyte-mediated clearance.

Circulating epithelial cell counts for monitoring the therapeutic outcome of patients with papillary thyroid carcinoma

Loco-regional recurrence or distant metastasis usually leads to the death of patients with papillary thyroid carcinoma (PTC). Whether or not circulating epithelial cells (CECs) count is a valuable marker in monitoring the therapeutic outcome of PTC was investigated. Patients with PTC (n=129) were treated in our medical center and were categorized into 4 groups with excellent (n=45), biochemical incomplete (n=15), indeterminate (n=37), and structural incomplete (n=32) responses. CECs were enriched from the peripheral blood by the PowerMag negative selection system. Three subtypes of CECs expressing epithelial cell adhesion molecule (EpCAM), thyroid-stimulating hormone receptor (TSHR, a marker for thyroid cells), and podoplanin (PDPN, a marker related to poor prognosis in patients with PTC) were defined by immunofluorescence staining, respectively. The median number of CECs (cells/mL of blood) expressing EpCAM, TSHR, and PDPN was 23 (interquartile range 10-61), 19 (interquartile range 8-50), and 8 (interquartile range 3-22), respectively, for patients enrolled in this study. The number of EpCAM+-CECs, TSHR+-CECs, and PDPN+-CECs was statistically different among patients in different treatment response groups without interference from anti-thyroglobulin antibody (P<0.0001). Patients with structural incomplete response had higher counts for all three CECs subtypes when compared to other patients. EpCAM+-CECs was better in distinguishing patients with excellent response from structural incomplete response among the three subtypes of CECs. The sensitivity and specificity of the assay was 84.4% and 95.6%, respectively, when the cut off value was 39 EpCAM+-CECs/mL. CECs testing can supplement the current standard methods for monitoring the therapeutic outcome of PTC.

Pathologists and liquid biopsies: to be or not to be?

Recently, the advent of therapies targeting genomic alterations has improved the care of patients with certain types of cancer. While molecular targets were initially detected in nucleic acid samples extracted from tumor tissue, detection of nucleic acids in circulating blood has allowed the development of what has become known as liquid biopsies, which provide a complementary and alternative sample source allowing identification of genomic alterations that might be addressed by targeted therapy. Consequently, liquid biopsies might rapidly revolutionize oncology practice in allowing administration of more effective treatments. Liquid biopsies also provide an approach towards short-term monitoring of metastatic cancer patients to evaluate efficacy of treatment and/or early detection of secondary mutations responsible for resistance to treatment. In this context, pathologists, who have already been required in recent years to take interest in the domain of molecular pathology of cancer, now face new challenges. The attitude of pathologists to and level of involvement in the practice of liquid biopsies, including mastering the methods employed in molecular analysis of blood samples, need close attention. Regardless of the level of involvement of pathologists in this new field, it is mandatory that oncologists, biologists, geneticists, and pathologists work together to coordinate the pre-analytical, analytical, and post-analytical phases of molecular assessment of tissue and liquid samples of individual cancer patients. The challenges include (1) implementation of effective and efficient procedures for reception and analysis of liquid and tissue samples for histopathological and molecular evaluation and (2) assuring short turn-around times to facilitate rapid optimization of individual patient treatment. In this paper, we will review the following: (1) recent data concerning the concept of liquid biopsies in oncology and its development for patient care, (2) advantages and limitations of molecular analyses performed on blood samples compared to those performed on tissue samples, and (3) short-term challenges facing pathologists in dealing with liquid biopsies of cancer patients and new strategies to early detect metastatic tumor cell clones.