Circulating tumor cells: Ready for translation?

Circulating tumor cells help differentiate benign ovarian lesions from cancer before surgery: A literature review and proof of concept study using flow cytometry with fluorescence imaging

Current tools are insufficient for distinguishing patients with ovarian cancer from those with benign ovarian lesions before extensive surgery. The present study utilized a readily accessible platform employing a negative selection strategy, followed by flow cytometry, to enumerate circulating tumor cells (CTCs) in patients with ovarian cancer. These counts were compared with those from patients with benign ovarian lesions. CTC counts at baseline, before and after anticancer therapy, and across various clinical scenarios involving ovarian lesions were assessed. A negative-selection protocol we proposed was applied to patients with suspected ovarian cancer and prospectively utilized in those subsequently confirmed to have malignancy. The protocol was implemented before anticancer therapy and at months 3, 6, 9 and 12 post-treatment. A cut-off value for CTC number at 4.75 cells/ml was established to distinguish ovarian malignancy from benign lesions, with an area under the curve of 0.900 (P<0.001). In patients with ovarian cancer, multivariate Cox regression analysis revealed that baseline CTC counts and the decline in CTCs within the first three months post-therapy were significant predictors of prolonged progression-free survival. Additionally, baseline CTC counts independently prognosticated overall survival. CTC counts obtained with the proposed platform, used in the present study, suggest that pre-operative CTC testing may be able to differentiate between malignant and benign tumors. Moreover, CTC counts may indicate oncologic outcomes in patients with ovarian cancer who have undergone cancer therapies.

Spheroids and organoids derived from colorectal cancer as tools for in vitro drug screening

Colorectal cancer (CRC) is a heterogeneous disease. Conventional two-dimensional (2D) culture employing cell lines was developed to study the molecular properties of CRC in vitro. Although these cell lines which are isolated from the tumor niche in which cancer develop, the translation to human model such as studying drug response is often hindered by the inability of cell lines to recapture original tumor features and the lack of heterogeneous clinical tumors represented by this 2D model, differed from in vivo condition. These limitations which may be overcome by utilizing three-dimensional (3D) culture consisting of spheroids and organoids. Over the past decade, great advancements have been made in optimizing culture method to establish spheroids and organoids of solid tumors including of CRC for multiple purposes including drug screening and establishing personalized medicine. These structures have been proven to be versatile and robust models to study CRC progression and deciphering its heterogeneity. This review will describe on advances in 3D culture technology and the application as well as the challenges of CRC-derived spheroids and organoids as a mode to screen for anticancer drugs.

A real-world comparison of circulating tumor cells in breast cancer from China: Novel device, CTC counts and its overall survival

Background

Both CellSearch and CellCollector have been accepted as the proper devices to capture CTC by domestic approval department. However, there is little article about the comparison between these two devices around the world. Herein, we conducted the real-world study to compare with these two devices and to re-verify the efficacy of CTC counts.

Methods

Patients who meet the following points should be included in the analysis. 1. Female, aged 18 years or older; 2. Eastern Cooperative Oncology Group (ECOG) score 0-2; 3. With at least one measurable tumor lesion; 4. Clear immunohistochemistry result; 5. Accept at least one CTC test. Patients were excluded in the analysis if they had a history of malignant tumors, incomplete follow-up information.

Results

536 metastatic breast cancer patients who had been detected for CTC at least once by CellSearch or CellCollector were included in the analysis. CellCollector in vivo CTC detection technology has a higher detection rate than the CellSearch system (69.2% vs 57.4%, P = 0.009). However, the proportion of CTC≥5 detected by CellSearch was higher than CellCollector (37.4% vs 16.3%, P < 0.001). There was a statistically significant difference in overall survival of patients with CTC negative and CTC positive (mOS:49.8 months vs 26.9 months). After 4 weeks of treatment, when CTC decreased by more than 50%, there was a significant difference in survival between the two groups (40.1 months vs 25.8 months, HR = 0.588, 95% CI: 0.350-0.933). In addition, for HER2-positive patients, Patients with CTC HER2 positive had longer overall survival than patients with CTC HER2 negative (median OS: 26.7 months vs 17.3 month, HR = 0.528, 95% CI: 0.269-0.887).

Conclusions

Real-world data indicate that CTC is an independent prognostic factor, and CellCollector and CellSearch have their own advantages in CTC detection.

Advances in novel strategies for isolation, characterization, and analysis of CTCs and ctDNA

Over the past decade, the detection and analysis of liquid biopsy biomarkers such as circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) have advanced significantly. They have received recognition for their clinical usefulness in detecting cancer at an early stage, monitoring disease, and evaluating treatment response. The emergence of liquid biopsy has been a helpful development, as it offers a minimally invasive, rapid, real-time monitoring, and possible alternative to traditional tissue biopsies. In resource-limited settings, the ideal platform for liquid biopsy should not only extract more CTCs or ctDNA from a minimal sample volume but also accurately represent the molecular heterogeneity of the patient's disease. This review covers novel strategies and advancements in CTC and ctDNA-based liquid biopsy platforms, including microfluidic applications and comprehensive analysis of molecular complexity. We discuss these systems' operational principles and performance efficiencies, as well as future opportunities and challenges for their implementation in clinical settings. In addition, we emphasize the importance of integrated platforms that incorporate machine learning and artificial intelligence in accurate liquid biopsy detection systems, which can greatly improve cancer management and enable precision diagnostics.

Liquid biopsies for cancer: From bench to clinic

Over the past two decades, liquid biopsy has been increasingly used as a supplement, or even, a replacement to the traditional biopsy in clinical oncological practice, due to its noninvasive and early detectable properties. The detections can be based on a variety of features extracted from tumor‑derived entities, such as quantitative alterations, genetic changes, and epigenetic aberrations, and so on. So far, the clinical applications of cancer liquid biopsy mainly aimed at two aspects, prediction (early diagnosis, prognosis and recurrent evaluation, therapeutic response monitoring, etc.) and intervention. In spite of the rapid development and great contributions achieved, cancer liquid biopsy is still a field under investigation and deserves more clinical practice. To better open up future work, here we systematically reviewed and compared the latest progress of the most widely recognized circulating components, including circulating tumor cells, cell-free circulating DNA, noncoding RNA, and nucleosomes, from their discovery histories to clinical values. According to the features applied, we particularly divided the contents into two parts, beyond epigenetics and epigenetic-based. The latter was considered as the highlight along with a brief overview of the advances in both experimental and bioinformatic approaches, due to its unique advantages and relatively lack of documentation.

Preclinical models for drug discovery for metastatic disease

Despite many advances, metastatic disease remains essentially uncurable. Thus, there is an urgent need to better understand mechanisms that promote metastasis, drive tumor evolution, and underlie innate and acquired drug resistance. Sophisticated preclinical models that recapitulate the complex tumor ecosystem are key to this process. We begin with syngeneic and patient-derived mouse models that are the backbone of most preclinical studies. Second, we present some unique advantages of fish and fly models. Third, we consider the strengths of 3D culture models for resolving remaining knowledge gaps. Finally, we provide vignettes on multiplexed technologies to advance our understanding of metastatic disease.

Circulating tumour cells in gastrointestinal cancers: food for thought?

Gastrointestinal (GI) cancers account for 35% of cancer-related deaths, predominantly due to their ability to spread and generate drug-tolerant metastases. Arising from different locations in the GI system, the majority of metastatic GI malignancies colonise the liver and the lungs. In this context, circulating tumour cells (CTCs) are playing a critical role in the formation of new metastases, and their presence in the blood of patients has been correlated with a poor outcome. In addition to their prognostic utility, prospective targeting of CTCs may represent a novel, yet ambitious strategy in the fight against metastasis. A better understanding of CTC biology, mechanistic underpinnings and weaknesses may facilitate the development of previously underappreciated anti-metastasis approaches. Here, along with related clinical studies, we outline a selection of the literature describing biological features of CTCs with an impact on their metastasis forming ability in different GI cancers.

Evaluating tumor cell- and T cell-derived extracellular vesicles as potential biomarkers of cancer and immune cell competence

INTRODUCTION

Extracellular vesicles (EVs) produced by tumors, also called tumor-derived exosomes (TEX), have been implicated in inducing immune cell suppression in vitro and in vivo. The development of a novel category of noninvasive biomarkers for precision oncology remains an unmet need, and TEX emerge as a promising liquid tumor biopsy component.

AREAS COVERED

TEX play a critical role in monitoring cancer presence/progression and in reprograming of anti-tumor effector T cells to producers of EVs with pro-tumor activity. TEX are a subset of circulating EVs. Their separation by immune capture from EVs derived from nonmalignant cells allows for TEX phenotypic/functional assessments. TEX cross-talking with CD3(+) T cells induce the release of CD3(+) small EV (sEV), whose cargo of suppressor proteins resembles that of TEX and further contributes to cancer-induced immune suppression. While TEX recapitulate the genetic/molecular phenotype of tumor cells, CD3(+) sEV might serve as 'T cell liquid biopsy.'

EXPERT OPINION

Preclinical explorations of the role in cancer body fluids of TEX and CD3(+) sEV as cancer biomarkers suggest that these EV subsets may qualify as liquid tumor biopsy noninvasive components in the near future. Their potential to simultaneously serve as noninvasive liquid tumor biopsy and T cell biopsy remains to be validated in future clinical trials.

Combined measurement of circulating tumor cell counts and serum tumor marker levels enhances the screening efficiency for malignant versus benign pulmonary nodules

BACKGROUND

The high false-positive rate for pulmonary nodules (PNs) from using low-dose computed tomography (LDCT) screening can lead to overuse of invasive procedures, overtreatment, and patient anxiety. Therefore, it is very important to develop new diagnostic methods.

METHODS

A negative enrichment-fluorescence in situ hybridization (NE-FISH) approach was used to detect circulating tumor cells (CTCs) in patients with PNs. We evaluated whether or not the combination of CTC counts with serum tumor marker levels (CEA, CA 125, CYFRA 21-1, SCC) could improve the diagnostic ability for distinguishing patients with malignant pulmonary nodules (MPNs) from those with benign pulmonary nodules (BPNs). Moreover, the potential clinical application of this combination for the diagnosis of solitary pulmonary nodules (SPNs) with a diameter ≤2 cm was also investigated.

RESULTS

The combination of CTC counts and tumor marker levels had a sensitivity of 80.12% and the area under the receiver operating characteristics curve (AUC_ROC ) of 0.853 (95% confidence interval [CI]: 0.800-0.897, p < 0.001) for the differential diagnosis of PNs. For early cancer stages, the sensitivity was 75.38% (AUC_ROC  = 0.780, 95% CI: 0.713-0.838, p < 0.001). In addition, for SPNs within 2 cm the combination of CTC counts and tumor marker levels was still the most valuable diagnostic tool with a sensitivity of 78.95% and AUC_ROC of 0.888.

CONCLUSION

The combination of CTC counts and serum tumor marker levels is helpful for improving the diagnosis of PNs, especially in the early stages of cancer and for SPNs within 2 cm.

Comparative analysis of capture methods for genomic profiling of circulating tumor cells in colorectal cancer

The genomic profiling of circulating tumor cells (CTCs) in the bloodstream should provide clinically relevant information on therapeutic efficacy and help predict cancer survival. Here, we contrasted the genomic profiles of CTC pools recovered from metastatic colorectal cancer (mCRC) patients using different enrichment strategies (CellSearch, Parsortix, and FACS). Mutations inferred in the CTC pools differed depending on the enrichment strategy and, in all cases, represented a subset of the mutations detected in the matched primary tumor samples. However, the CTC pools from Parsortix, and in part, CellSearch, showed diversity estimates, mutational signatures, and drug-suitability scores remarkably close to those found in matching primary tumor samples. In addition, FACS CTC pools were enriched in apparent sequencing artifacts, leading to much higher genomic diversity estimates. Our results highlight the utility of CTCs to assess the genomic heterogeneity of individual tumors and help clinicians prioritize drugs in mCRC.

Circulating Tumor Cells and Breast Cancer Metastasis: From Enumeration to Somatic Mutational Profile

Aims: This study investigates the association between circulating tumor cells (CTCs) and breast cancer metastasis. Methods: A retrospective study was conducted using patients with histologically confirmed breast cancer recruited from the First Affiliated Hospital of Nanjing Medical University during the period of August 2017−October 2020. We used adjusted logistic regression, the random forest algorithm, and sensitivity analysis to study the association between CTC enumeration and tumor metastasis. Further, we performed next-generation sequencing (NGS) on the CTCs obtained from two patients with breast cancer brain metastasis. Results: A total of 41 out of 116 enrolled patients were identified with tumor metastasis. CTC enumeration was significantly higher in patients with liver metastasis than in those without liver metastasis. Patients with CTCs ≥ 5 exhibited a higher risk of tumor metastasis than those with CTCs < 5 in the adjusted model (odds ratios (OR) = 6.25, 95% confidence interval (CI) = 2.63−15.58). The random forest model identified CTC enumeration as a significant metastasis-related variable with the highest mean decrease accuracy and mean decrease Gini score. No significant association was found between CTCs and visceral metastasis with an OR of 1.29 (95% CI = 0.98−2.05, p = 0.232). Upon further investigating organ-specific metastasis, we found that patients with high CTC levels were more likely to develop liver metastasis (OR = 4.87, 95% CI = 1.34−20.17, p = 0.021). The NGS study of CTCs identified a total of 120 indel mutations (e.g., CNGB1, NTSR1, ZG16). The enriched biological processes were mechanoreceptor differentiation and macrophage activation involved in the immune response. The enriched KEGG pathways included focal adhesion, the PI3K-Akt signaling pathway, and microRNAs involved in cancer. Conclusions: Our study revealed that CTCs ≥ 5 are a risk factor for tumor metastasis in breast cancer patients. In addition, we reported that CTCs ≥ 5 might be associated with a higher risk of liver metastasis in patients with metastatic breast cancer. We have provided the mutational profiles of CTCs based on next-generation sequencing.

Circulating tumor cell isolation for cancer diagnosis and prognosis

Circulating tumor cells (CTCs) are tumor cells that shed from the primary tumor and intravasate into the peripheral blood circulation system responsible for metastasis. Sensitive detection of CTCs from clinical samples can serve as an effective tool in cancer diagnosis and prognosis through liquid biopsy. Current CTC detection technologies mainly reply on the biomarker-mediated platforms including magnetic beads, microfluidic chips or size-sensitive microfiltration which can compromise detection sensitivity due to tumor heterogeneity. A more sensitive, biomarker independent CTCs isolation technique has been recently developed with the surface-charged superparamagnetic nanoprobe capable of different EMT subpopulation CTC capture from 1 mL clinical blood. In this review, this new strategy is compared with the conventional techniques on biomarker specificity, impact of protein corona, effect of glycolysis on cell surface charge, and accurate CTC identification. Correlations between CTC enumeration and molecular profiling in clinical blood and cancer prognosis are provided for clinical cancer management.

In vitro cultures of circulating tumor cells: a potential tool to unravel drug sensitivity

Since taking part as leading actors in driving the metastatic process, circulating tumor cells (CTCs) have displayed a wide range of potential applications in the cancer-related research field. Besides their well-proved prognostic value, the role of CTCs in both predictive and diagnostics terms might be extremely informative about cancer properties and therefore highly helpful in the clinical decision-making process. Unfortunately, CTCs are scarcely released in the blood circulation and their counts vary a lot among different types of cancer, therefore CTC detection and consequent characterization are still highly challenging. In this context, in vitro CTC cultures could potentially offer a great opportunity to expand the number of tumor cells isolated at different stages of the disease and thus simplify the analysis of their biological and molecular features, allowing a deeper comprehension of the nature of neoplastic diseases. The aim of this review is to highlight the main attempts to establish in vitro CTC cultures from patients harboring different tumor types in order to highlight how powerful this practice could be, especially in optimizing the therapeutic strategies available in clinical practice and potentially preventing or contrasting the development of treatment resistance.

Extracellular Vesicle-Based Multianalyte Liquid Biopsy as a Diagnostic for Cancer

Liquid biopsy is the analysis of materials shed by tumors into circulation, such as circulating tumor cells, nucleic acids, and extracellular vesicles (EVs), for the diagnosis and management of cancer. These assays have rapidly evolved with recent FDA approvals of single biomarkers in patients with advanced metastatic disease. However, they have lacked sensitivity or specificity as a diagnostic in early-stage cancer, primarily due to low concentrations in circulating plasma. EVs, membrane-enclosed nanoscale vesicles shed by tumor and other cells into circulation, are a promising liquid biopsy analyte owing to their protein and nucleic acid cargoes carried from their mother cells, their surface proteins specific to their cells of origin, and their higher concentrations over other noninvasive biomarkers across disease stages. Recently, the combination of EVs with non-EV biomarkers has driven improvements in sensitivity and accuracy; this has been fueled by the use of machine learning (ML) to algorithmically identify and combine multiple biomarkers into a composite biomarker for clinical prediction. This review presents an analysis of EV isolation methods, surveys approaches for and issues with using ML in multianalyte EV datasets, and describes best practices for bringing multianalyte liquid biopsy to clinical implementation. Expected final online publication date for the Annual Review of Biomedical Data Science, Volume 5 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

PillarX: A Microfluidic Device to Profile Circulating Tumor Cell Clusters Based on Geometry, Deformability, and Epithelial State

Circulating tumor cell (CTC) clusters are associated with increased metastatic potential and worse patient prognosis, but are rare, difficult to count, and poorly characterized biophysically. The PillarX device described here is a bimodular microfluidic device (Pillar-device and an X-magnetic device) to profile single CTCs and clusters from whole blood based on their size, deformability, and epithelial marker expression. Larger, less deformable clusters and large single cells are captured in the Pillar-device and sorted according to pillar gap sizes. Smaller, deformable clusters and single cells are subsequently captured in the X-device and separated based on epithelial marker expression using functionalized magnetic nanoparticles. Clusters of established and primary breast cancer cells with variable degrees of cohesion driven by different cell-cell adhesion protein expression are profiled in the device. Cohesive clusters exhibit a lower deformability as they travel through the pillar array, relative to less cohesive clusters, and have greater collective invasive behavior. The ability of the PillarX device to capture clusters is validated in mouse models and patients of metastatic breast cancer. Thus, this device effectively enumerates and profiles CTC clusters based on their unique geometrical, physical, and biochemical properties, and could form the basis of a novel prognostic clinical tool.

An organoid model of colorectal circulating tumor cells with stem cell features, hybrid EMT state and distinctive therapy response profile

Background

Circulating tumor cells (CTCs) are responsible for the metastatic dissemination of colorectal cancer (CRC) to the liver, lungs and lymph nodes. CTCs rarity and heterogeneity strongly limit the elucidation of their biological features, as well as preclinical drug sensitivity studies aimed at metastasis prevention.

Methods

We generated organoids from CTCs isolated from an orthotopic CRC xenograft model. CTCs-derived organoids (CTCDOs) were characterized through proteome profiling, immunohistochemistry, immunofluorescence, flow cytometry, tumor-forming capacity and drug screening assays. The expression of intra- and extracellular markers found in CTCDOs was validated on CTCs isolated from the peripheral blood of CRC patients.

Results

CTCDOs exhibited a hybrid epithelial-mesenchymal transition (EMT) state and an increased expression of stemness-associated markers including the two homeobox transcription factors Goosecoid and Pancreatic Duodenal Homeobox Gene-1 (PDX1), which were also detected in CTCs from CRC patients. Functionally, CTCDOs showed a higher migratory/invasive ability and a different response to pathway-targeted drugs as compared to xenograft-derived organoids (XDOs). Specifically, CTCDOs were more sensitive than XDOs to drugs affecting the Survivin pathway, which decreased the levels of Survivin and X-Linked Inhibitor of Apoptosis Protein (XIAP) inducing CTCDOs death.

Conclusions

These results indicate that CTCDOs recapitulate several features of colorectal CTCs and may be used to investigate the features of metastatic CRC cells, to identify new prognostic biomarkers and to devise new potential strategies for metastasis prevention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02263-y.

Neutrophil Cyto-Pharmaceuticals Suppressing Tumor Metastasis via Inhibiting Hypoxia-Inducible Factor-1α in Circulating Breast Cancer Cells

Circulating tumor cells (CTCs) are reported as the precursor of tumor metastases, implying that stifling CTCs would be beneficial for metastasis prevention. However, challenges remain for the application of therapies that aim at CTCs due to lack of effective CTC-targeting strategy and sensitive therapeutic agents. Herein, a general CTC-intervention strategy based on neutrophil cyto-pharmaceuticals is proposed for suppressing CTC colonization and metastasis formation. Breast cancer 4T1 cells are infused as the mimic CTCs, and 4T1 cells trapped are first elucidated in neutrophil extracellular traps (NETs) expressing high levels of hypoxia-inducible factor-1α (HIF-1α) due to NET formation and thus promoting tumor cell colonization through enhanced migration, invasion and stemness. After verifying HIF-1α as a potential target for metastasis prevention, living neutrophil cyto-pharmaceuticals (CytPNEs) loaded with HIF-1α inhibitor are fabricated to therapeutically inhibit HIF-1α. It is demonstrated that CytPNEs can specially convey the HIF-1α inhibitor to 4T1 cells according to the inflammatory chemotaxis of neutrophils and down-regulate HIF-1α, thereby inhibiting metastasis and prolonging the median survival of mice bearing breast cancer lung metastasis. The research offers a new perspective for understanding the mechanism of CTC colonization, and puts forward the strategy of targeted intervention of CTCs as a meaningful treatment for tumor metastasis.

Interaction between avian leukosis virus subgroup J surface protein and doublecortin-like kinase 1 accelerates cell proliferation and epithelial-mesenchymal transition

Avian leukosis virus subgroup J (ALV-J) induces myelocytomas, which can metastasize to multiple organs in diseased chicken. Although metastasis is the primary cause of death in such cases, the mechanism for it remains unclear. Here, we found that interaction between ALV-J surface protein (SU) and doublecortin-like kinase 1 (DCLK1) promotes epithelial-mesenchymal transition (EMT) and cell proliferation. We found that ALV-J can activate EMT in infected cells. Subsequently, proteomics analysis revealed that DCLK1, a well-established putative tumor stem cell marker, which is highly expressed in ALV-J-infected DF-1 cells and chickens, might be a potential factor mediating EMT. Furthermore, using immunofluorescence and immunoprecipitation, we verified that SU interacts with DCLK1. Functional studies suggested that overexpression of DCLK1 increased viral replication, and promoted cell proliferation by accelerating the progression of cells from the G0/G1 phase to the S phase of cell cycle, whereas RNA-interference of DCLK1 reduced viral replication and arrested cell proliferation by retarding cell cycle progression from the late G1 phase into the S phase in ALV-J-infected cells. Moreover, we demonstrate that the increased accumulation of DCLK1 promotes EMT by increasing the expression of N-cadherin, vimentin, MMP2, transcription factor Snail1, and decreasing the expression of epithelial marker E-cadherin. These results suggest that ALV-J SU interacts with DCLK1, and accelerates cell proliferation, leading to increased viral replication, and ultimately activating EMT, which paves the way for tumor metastasis. IMPORTANCE Tumor metastasis is a major challenge in cancer research, because of its systemic nature and the resistance of disseminated tumor cells to existing therapeutic agents. It is estimated that >90% of mortality from cancer is attributable to metastases. We found that ALV-J can activate EMT, which plays a critical role in cancer metastasis. Subsequently, we identified a tumor stem cell marker, DCLK1, in ALV-J infected cells, which interacts with surface protein (SU) of ALV-J to promote virus replication, activate EMT, and accelerate cell proliferation enabling ALV-J to obtain metastatic ability. Understanding the process of participation of ALV-J in EMT and the route of metastasis will help elucidate the mechanism of virus-induced tumor metastasis, and help identify promising molecular targets and key obstacles for ALV-J control and clinical technology development.

Circulating Tumor Cell Transcriptomics as Biopsy Surrogates in Metastatic Breast Cancer

BACKGROUND

Metastatic breast cancer (MBC) and the circulating tumor cells (CTCs) leading to macrometastases are inherently different than primary breast cancer. We evaluated whether whole transcriptome RNA-Seq of CTCs isolated via an epitope-independent approach may serve as a surrogate for biopsies of macrometastases.

METHODS

We performed RNA-Seq on fresh metastatic tumor biopsies, CTCs, and peripheral blood (PB) from 19 newly diagnosed MBC patients. CTCs were harvested using the ANGLE Parsortix microfluidics system to isolate cells based on size and deformability, independent of a priori knowledge of cell surface marker expression.

RESULTS

Gene expression separated CTCs, metastatic biopsies, and PB into distinct groups despite heterogeneity between patients and sample types. CTCs showed higher expression of immune oncology targets compared with corresponding metastases and PB. Predictive biomarker (n = 64) expression was highly concordant for CTCs and metastases. Repeat observation data post-treatment demonstrated changes in the activation of different biological pathways. Somatic single nucleotide variant analysis showed increasing mutational complexity over time.

CONCLUSION

We demonstrate that RNA-Seq of CTCs could serve as a surrogate biomarker for breast cancer macrometastasis and yield clinically relevant insights into disease biology and clinically actionable targets.

CNA Profiling of Single CTCs in Locally Advanced Esophageal Cancer Patients during Therapy Highlights Unexplored Molecular Pathways

BACKGROUND

Here, we monitored the evolution of CTCs spread in 11 patients affected by locally advanced EC who were undergoing therapy.

METHODS

In this perspective study, we designed multiple blood biopsies from individual patients: before and after neoadjuvant chemo-radio therapy and after surgery. We developed a multi-target array, named Grab-all assay, to estimate CTCs for their epithelial (EpCAM/E-Cadherin/Cytokeratins) and mesenchymal/stem (N-Cadherin/CD44v6/ABCG2) phenotypes. Identified CTCs were isolated as single cells by DEPArray, subjected to whole genome amplification, and copy number aberration (CNA) profiles were determined. Through bioinformatic analysis, we assessed the genomic imbalance of single CTCs, investigated specific focal copy number changes previously reported in EC and aberrant pathways using enrichment analysis.

RESULTS

Longitudinal monitoring allowed the identification of CTCs in at least one time-point per patient. Through single cell CNA analysis, we revealed that CTCs showed significantly dynamic genomic imbalance during treatment. Individual CTCs from relapsed patients displayed a higher degree of genomic imbalance relative to disease-free patients' groups. Genomic aberrations previously reported in EC occurred mostly in post-neoadjuvant therapy CTCs. In-depth analysis showed that networks enrichment in all time-point CTCs were inherent to innate immune system. Transcription/gene regulation, post-transcriptional and epigenetic modifications were uniquely affected in CTCs of relapsed patients.

CONCLUSIONS

Our data add clues to the comprehension of the role of CTCs in EC aggressiveness: chromosomal aberrations on genes related to innate immune system behave as relevant to the onset of CTC-status, whilst pathways of transcription/gene regulation, post-transcriptional and epigenetic modifications seem linked to patients' outcome.

Recent advances in lung cancer genomics: Application in targeted therapy

Genomic characterization of lung cancer has not only improved our understanding of disease biology and carcinogenesis but also revealed several therapeutic opportunities. Targeting tumor dependencies on specific genomic alterations (oncogene addiction) has accelerated the therapeutic developments and significantly improved the outcomes even in advanced stage of disease. Identification of genomic alterations predicting response to specific targeted treatment is the key to success for this "personalized treatment" approach. Availability of multiple choices of therapeutic options for specific genomic alterations highlight the importance of optimum sequencing of drugs. Multiplex gene testing has become mandatory in view of constantly increasing number of therapeutic targets and effective treatment options. Influence of genomic characteristics on response to immunotherapy further makes comprehensive genomic profiling necessary before therapeutic decision making. A comprehensive elucidation of resistance mechanisms and directed treatments have made the continuum of care possible and transformed this deadly disease into a chronic condition. Liquid biopsy-based approach has made the dynamic monitoring of disease possible and enabled treatment optimizations accordingly. Current lung cancer management is the perfect example of "precision-medicine" in clinical oncology.

Engineered multifunctional metal-phenolic nanocoatings for label-free capture and "self-release" of heterogeneous circulating tumor cells

Immunomagnetic beads have been widely explored as an important analytical tool for the rapid and sensitive detection of circulating tumor cells (CTCs). However, their clinical application is seriously hindered by the tedious preparation procedures and heterogeneous nature of CTCs. To this end, a designed multifunctional platform named Fe₃O₄@TA/Cu^II superparamagnetic nanoparticles (SPMNPs) is expected to have the following features: (i) the formation of a tannic acid-copper (II) ion (TA/Cu^II) coating which could be accomplished by a one-step method is very simple; (ii) the TA/Cu^II coating shows high affinity for heterogeneous CTCs and good resistance to nonspecific adhesion of blood cells; (iii) "self-release" of the captured cells could be achieved as the TA/Cu^II coating gradually degrades in the cell culture environment without any additional interventions. Therefore, the resulting Fe₃O₄@TA/Cu^II SPMNPs could capture various CTCs (MCF-7, HepG2 and HeLa cells) with different expression levels of the epithelial cell adhesion molecule (EpCAM). And the capture efficiency and cell purity can reach 88% and 87%, respectively. In addition, 68% of the captured cells are self-released after 6 h of incubation and most of the released cells show high cell proliferation activity. In particular, Fe₃O₄@TA/Cu^II SPMNPs can successfully detect 1-13 CTCs from 1 mL of blood of 14 patients with 6 types of cancers. Hence, we expect that the as-prepared Fe₃O₄@TA/Cu^II SPMNPs with simple, efficient, and universal yet cost-efficient characteristics could act as a promising analytical tool for clinical CTC detection.

Circulating Tumor Cells: Technologies and Their Clinical Potential in Cancer Metastasis

Circulating tumor cells (CTCs) are single cells or clusters of cells within the circulatory system of a cancer patient. While most CTCs will perish, a small proportion will proceed to colonize the metastatic niche. The clinical importance of CTCs was reaffirmed by the 2008 FDA approval of CellSearch^®, a platform that could extract EpCAM-positive, CD45-negative cells from whole blood samples. Many further studies have demonstrated the presence of CTCs to stratify patients based on overall and progression-free survival, among other clinical indices. Given their unique role in metastasis, CTCs could also offer a glimpse into the genetic drivers of metastasis. Investigation of CTCs has already led to groundbreaking discoveries such as receptor switching between primary tumors and metastatic nodules in breast cancer, which could greatly affect disease management, as well as CTC-immune cell interactions that enhance colonization. In this review, we will highlight the growing variety of isolation techniques for investigating CTCs. Next, we will provide clinically relevant context for CTCs, discussing key clinical trials involving CTCs. Finally, we will provide insight into the future of CTC studies and some questions that CTCs are primed to answer.

Identification of Expression Patterns and Potential Prognostic Significance of m5C-Related Regulators in Head and Neck Squamous Cell Carcinoma

5-Methylcytosine (m⁵C) methylation is a major epigenetic technique of RNA modification and is dynamically mediated by m⁵C “writers,” “erasers,” and “readers.” m⁵C RNA modification and its regulators are implicated in the onset and development of many tumors, but their roles in head and neck squamous cell carcinoma (HNSCC) have not yet been completely elucidated. In this study, we examined expression patterns of core m⁵C regulators in the publicly available HNSCC cohort via bioinformatic methods. The differentially expressed m⁵C regulators could divide the HNSCC cohort into four subgroups with distinct prognostic characteristics. Furthermore, a three-gene expression signature model, comprised of NSUN5, DNMT1, and DNMT3A, was established to identify individuals with a high or low risk of HNSCC. To explore the underlying mechanism in the prognosis of HNSCC, screening of differentially expressed genes, followed by the analysis of functional and pathway enrichment, from individuals with high- or low-risk HNSCC was performed. The results revealed a critical role for m⁵C RNA modification in two aspects of HNSCC: (1) dynamic m⁵C modification contributes to the regulation of HNSCC progression and (2) expression patterns of NSUN5, DNMT1, and DNMT3A help to predict the prognosis of HNSCC.

Genomic Instability in Circulating Tumor Cells

Simple Summary

In this review, we focus on recent advances in the detection and quantification of tumor cell heterogeneity and genomic instability of CTCs and the contribution of chromosome instability studies to genetic heterogeneity in CTCs at the single-CTC level.

Abstract

Circulating tumor cells (CTCs) can promote distant metastases and can be obtained through minimally invasive liquid biopsy for clinical assessment in cancer patients. Having both genomic heterogeneity and instability as common features, the genetic characterization of CTCs can serve as a powerful tool for a better understanding of the molecular changes occurring at tumor initiation and during tumor progression/metastasis. In this review, we will highlight recent advances in the detection and quantification of tumor cell heterogeneity and genomic instability in CTCs. We will focus on the contribution of chromosome instability studies to genetic heterogeneity in CTCs at the single-CTC level by discussing data from different cancer subtypes and their impact on diagnosis and precision medicine.

Preclinical and Clinical Evaluation of Magnetic-Activated Cell Separation Technology for CTC Isolation in Breast Cancer

Circulating tumor cell (CTC) count is an independent prognostic factor in early breast cancer. CTCs can be found in the blood of 20% of patients prior to neoadjuvant therapy. We aimed to assess the suitability of magnetic-activated cell separation (MACS) technology for isolation and cytological characterization of CTCs. In the preclinical part of the study, cell lines were spiked into buffy coat samples derived from healthy donors, and isolated using MACS. Breast cancer cells with preserved cell morphology were successfully isolated. In the clinical part, blood for CTC isolation was drawn from 44 patients with early and locally advanced breast cancer prior to neoadjuvant chemotherapy. Standard Giemsa, Papanicolaou and pancytokeratin staining was applied. 2.3% of samples contained cells that meet both the morphological and immunocytochemical criteria for CTC. In 32.6% of samples, partially degenerated pancytokeratin negative cells with morphological features of tumor cells were observed. In 65.1% of samples, CTCs were not found. In conclusion, our results demonstrate that morphologically intact tumor cells can be isolated using MACS technology. However, morphologically intact tumor cells were not detected in the clinical part of the study. At present, MACS technology does not appear suitable for use in a clinical cytopathology laboratory.