Isolation of Circulating Tumor Cells

High-gradient microstructured hybrid microfluidic chip for rare tumor cell capture

Cancer remains the leading cause of death worldwide, and early detection can significantly reduce patient mortality. Circulating tumor cells (CTCs), which are tumor cells shed from the primary tumor and transported to distant sites through the bloodstream, are key biomarkers for cancer diagnosis and contain critical information reflecting the primary tumor, making them important for monitoring cancer progression. Microfluidic chips utilizing a purely physical capture technique based on the size and deformability differences between CTCs and other blood cells have proven to be effective in capturing CTCs. This study investigates three high-gradient microstructured hybrid microfluidic chips (HGMH-Chips), each incorporating a microarray structure and a distinct geometric gradient design: linear, sawtooth, and waveform. Multiphysics simulations revealed significant differences in pressure distribution among the chip configurations. Notably, the sawtooth design exhibited a more uniform pressure drop, with only 25% of the particles in the high-pressure region. We employed two cancer cell lines (MDA-MB-231 and A549) to evaluate the chip's capture capability. Additionally, we compared the capture efficiency and cell viability across the three designs in a single cancer cell system. Experimental results demonstrated that the sawtooth chip achieved a capture efficiency of up to 70%. When applied to mixed samples containing leukocytes, the high-gradient design exhibited a capture purity of up to 98%, effectively isolating a small number of cancer cells from complex samples. This model holds promise for the capture of CTCs in complex systems. Furthermore, the microarray structure aids in stabilizing the captured cancer cells, enhancing separation efficiency. This study presents a novel chip structure design for tumor cell capture, which holds promise for improving the capture of tumor cells in complex biological samples.

Epitope Expression Persists in Circulating Tumor Cells as Breast Cancers Acquire Resistance to Antibody Drug Conjugates

Antibody-drug conjugates (ADCs) targeting cell surface proteins TROP2 or HER2 are effective in metastatic breast cancer, but the precise clinical contribution of epitope expression is uncertain. We prospectively monitored circulating tumor cells (CTCs) in 33 patients receiving ADC therapies using quantitative imaging. The expression of TROP2 and HER2 are heterogeneous across single CTCs from untreated patients, comparable to matched tumor biopsies, and display poor association with clinical response. Within three weeks of treatment initiation, declining CTC numbers correlate with a durable response (TROP2: median time to progression 391 versus 97 days, HR 4.15, P=0.0046; HER2: 322 versus 66 days, HR 9.12, P=0.0002). Neither TROP2 nor HER2 expression is reduced at progression, compared to matched pretreatment CTCs, and switching ADC epitope while maintaining a similar payload shows poor efficacy. Thus, epitope downregulation is not a common driver of acquired resistance to TROP2 or HER2 ADCs, and second-line ADC therapies may benefit from distinct payloads.

SIGNIFICANCE

ADCs target tumor-associated antigens, followed by internalization and release of drug payloads. However, clinical studies of epithelial-targeting ADCs show efficacy despite low tumor epitope expression. Our finding that epitope downregulation does not commonly accompany acquired resistance suggests alternative drivers of clinical efficacy and the need for testing non-cross-resistant payloads to overcome resistance.

Advancements in Circulating Tumor Cell Detection for Early Cancer Diagnosis: An Integration of Machine Learning Algorithms with Microfluidic Technologies

Circulating tumor cells (CTCs) are vital indicators of metastasis and provide a non-invasive method for early cancer diagnosis, prognosis, and therapeutic monitoring. However, their low prevalence and heterogeneity in the bloodstream pose significant challenges for detection. Microfluidic systems, or "lab-on-a-chip" devices, have emerged as a revolutionary tool in liquid biopsy, enabling efficient isolation and analysis of CTCs. These systems offer advantages such as reduced sample volume, enhanced sensitivity, and the ability to integrate multiple processes into a single platform. Several microfluidic techniques, including size-based filtration, dielectrophoresis, and immunoaffinity capture, have been developed to enhance CTC detection. The integration of machine learning (ML) with microfluidic systems has further improved the specificity and accuracy of CTC detection, significantly advancing the speed and efficiency of early cancer diagnosis. ML models have enabled more precise analysis of CTCs by automating detection processes and enhancing the ability to identify rare and heterogeneous cell populations. These advancements have already demonstrated their potential in improving diagnostic accuracy and enabling more personalized treatment approaches. In this review, we highlight the latest progress in the integration of microfluidic technologies and ML algorithms, emphasizing how their combination has changed early cancer diagnosis and contributed to significant advancements in this field.

Circulation tumor cell isolation and enrichment technologies

During cancer metastasis, tumor cells migrate from the primary tumor site and spread to distant tissue or organs through the circulatory system of the body. While it is challenging to track metastatic tumor cells, circulating tumor cells (CTCs) via liquid biopsy provide a unique and important opportunity for longitudinal monitoring of residual cancer diseases and progression, showing great potential to facilitate precision medicine in cancer patients. The enumeration and characterization of CTCs represent prognostic and predictive biomarkers, which can be used to monitor the response to and efficacy of various therapies. Along with molecular and cellular features of CTCs, this data can inform the detection of early micro-metastases and assess progression of advanced disease in a more sensitive manner than traditional imaging modalities, serving as a complementary approach with added value. Nevertheless, comprehensive multiomic analyses of CTCs at inter-cellular (cluster), single-cell, and subcellular levels to elucidate relevant CTC cancer biology, tumor immune ecosystem biology, and clinical outcomes have yet to be achieved, demanding multidisciplinary collaboration to advance the field. Complementary to the published chapter on multiomic analyses and functional properties of CTCs, this chapter summarizes key methods and integrated strategies in CTC isolation, highlighting an accelerated evolution in high-throughput analysis of CTCs.

Plasma treatment can efficiently increase the attachment of pancreatic circulatory tumor cells to the surface

Pancreatic cancer ranks as the fourth most common cause of cancer-related fatalities globally, with a notably low 5-year relative survival rate. We need to immediately develop fast, dependable, and noninvasive diagnostic techniques that can accurately identify pancreatic cancer at an early stage. The research project created a straightforward but effective method for detecting and increasing the amount of tumor cells that could bind to polystyrene (PS) well plates. To significantly improve the adhesion of the pancreatic cancer cell line PANC-1 on PS well plates, a 5-min exposure to high-power oxygen plasma was implemented. This treatment caused a significant increase in surface energy and roughness. Surface characterization was assessed by utilizing an atomic force microscope and X-ray photoelectron spectroscopy. Water contact angle measurement is used to assess the level of wettability present on the treated surface. To determine how well the circulatory tumor cells (CTCs) model adheres to a plasma-treated surface (PTS), appropriate amounts of mCherry-labeled PANC-1 cells are mixed into a sample of blood cells to mimic clinical conditions. After applying plasma treatment, the experiment achieved a 96% success rate in binding at 2 h, specifically for the PANC-1 cell type. Moreover, the platform demonstrated a considerable ability to attach to cancerous cells compared to non-cancerous cells found in blood. To summarize, this study has shown that non-thermal plasma treatment could be a novel and efficient method for the better adhesion of pancreatic cancer cells, with the benefits of being cost-effective and quick. It is necessary for additional research to be conducted to confirm the clinical efficacy of the method.

Haematogenous seeding in mycosis fungoides and Sézary syndrome: current evidence and clinical implications

Cutaneous T-cell lymphomas (CTCLs) are a heterogeneous group of diseases characterized by abnormal neoplastic T-cell growth in the skin. Mycosis fungoides (MF), the most common CTCL, manifests as erythematous skin patches and/or plaques, tumours or erythroderma. The disease may involve blood, lymph nodes and rarely viscera. Sézary syndrome (SS) is a unique leukaemia/lymphoma syndrome related to MF, which presents with blood and skin involvement at diagnosis. The pathogenesis of MF/SS is not fully elucidated. The presence of skin lesions at distant sites underpins a hypothesis that MF/SS lesions may develop through haematogenous seeding. Phenotypic similarities between malignant and normal T cells led to the notion that disease-initiating mutations occur in specific subtypes of mature T cells, which are responsible for most CTCLs. However, this mature T-cell precursor model is not always consistent with clinical observations and research on MF/SS pathogenesis. Here, we review evidence supporting an alternative model of pathogenesis for MF/SS involving haematogenous seeding as a key process responsible for the initiation and progression of the disease. According to this hypothesis, malignant transformation occurs at an early stage of T-cell development (probably in bone marrow or thymus), yielding circulating neoplastic T cells which colonize the skin where the microenvironment is most permissive for proliferation and evolution. These mutated precursor cells seed the skin where they find a suitable niche to develop into clinically perceptible disease. Subsequently, malignant T cells can re-enter the bloodstream, re-seed pre-existing lesions and seed new areas of the skin, causing synchronous and convergent changes in the transcriptomic profile of lesions and tumours, and clinical disease progression - 'consecutive haematogenous seeding' captures this temporal phenomenon. This model radically changes the current understanding of CTCL pathogenesis, transforming it from a primarily cutaneous disease with secondary involvement of blood, to a systemic disease, where the spread of malignant cells through the blood to the skin is not a phenomenon of advanced disease but is an essential component of pathogenesis. This understanding of MF/SS could have several clinical implications, including standardizing our approach to assessing blood tumour burden, potential advances in prognosis and monitoring, and investigating combination treatments to improve patient outcomes.

Liquid biopsy in hepatocellular carcinoma: Challenges, advances, and clinical implications

Hepatocellular carcinoma (HCC) is an aggressive primary liver malignancy often diagnosed at an advanced stage, resulting in a poor prognosis. Accurate risk stratification and early detection of HCC are critical unmet needs for improving outcomes. Several blood-based biomarkers and imaging tests are available for early detection, prediction, and monitoring of HCC. However, serum protein biomarkers such as alpha-fetoprotein have shown relatively low sensitivity, leading to inaccurate performance. Imaging studies also face limitations related to suboptimal accuracy, high cost, and limited implementation. Recently, liquid biopsy techniques have gained attention for addressing these unmet needs. Liquid biopsy is non-invasive and provides more objective readouts, requiring less reliance on healthcare professional's skills compared to imaging. Circulating tumor cells, cell-free DNA, and extracellular vesicles are targeted in liquid biopsies as novel biomarkers for HCC. Despite their potential, there are debates regarding the role of these novel biomarkers in the HCC care continuum. This review article aims to discuss the technical challenges, recent technical advancements, advantages and disadvantages of these liquid biopsies, as well as their current clinical application and future directions of liquid biopsy in HCC.

Tumor cell-based liquid biopsy using high-throughput microfluidic enrichment of entire leukapheresis product

Circulating Tumor Cells (CTCs) in blood encompass DNA, RNA, and protein biomarkers, but clinical utility is limited by their rarity. To enable tumor epitope-agnostic interrogation of large blood volumes, we developed a high-throughput microfluidic device, depleting hematopoietic cells through high-flow channels and force-amplifying magnetic lenses. Here, we apply this technology to analyze patient-derived leukapheresis products, interrogating a mean blood volume of 5.83 liters from seven patients with metastatic cancer. High CTC yields (mean 10,057 CTCs per patient; range 100 to 58,125) reveal considerable intra-patient heterogeneity. CTC size varies within patients, with 67% overlapping in diameter with WBCs. Paired single-cell DNA and RNA sequencing identifies subclonal patterns of aneuploidy and distinct signaling pathways within CTCs. In prostate cancers, a subpopulation of small aneuploid cells lacking epithelial markers is enriched for neuroendocrine signatures. Pooling of CNV-confirmed CTCs enables whole exome sequencing with high mutant allele fractions. High-throughput CTC enrichment thus enables cell-based liquid biopsy for comprehensive monitoring of cancer.

Enrichment and separation technology for evaluation of circulating tumor cells

Circulating tumor cells (CTCs) are tumor cells that exist in human peripheral blood, which could spread to other tissues or organs via the blood circulation system and develop into metastatic foci, leading to tumor recurrence or metastasis in postoperative patients and thereby increasing the mortality of malignant tumor patients. Evaluation of CTC levels can be used for tumor metastasis prediction, prognosis evaluation, drug exploitation, individualized treatment, liquid biopsy, etc., which exhibit outstanding clinical application prospects. In recent years, accurately capturing and analyzing CTCs has become a research hotspot in the early diagnosis and precise treatment of tumors. This review summarized various enrichment and isolation technologies for evaluating CTCs based on the design principle and discussed the challenges and perspectives in this field.

Liquid biomarkers in prostate cancer: recent advancements and future directions

PURPOSE OF REVIEW

Traditional diagnostic approaches of prostate cancer like PSA are limited by high false-positive rates and insufficient capture of tumour heterogeneity, necessitating the development of more precise tools. This review examines the latest advancements in liquid biomarkers for prostate cancer, focusing on their potential to refine diagnostic accuracy and monitor disease progression.

RECENT FINDINGS

Liquid biomarkers have gained prominence because of their minimally invasive nature and ability to reflect the molecular characteristics of prostate cancer. Circulating tumour cells provide insight into tumour cell dissemination and are indicative of aggressive disease phenotypes, with single-cell analyses revealing genomic instability and treatment resistance. Circulating tumour DNA offers real-time tumour genomic information, aiding in treatment decision-making in advanced prostate cancer, where it has been associated with clinical progression. MicroRNAs act as oncogenes or tumour suppressors and exhibit diagnostic and prognostic potential; however, their clinical utility is constrained by the lack of consistent validation. Extracellular vesicles contain tumour-derived biomolecules, with specific proteins demonstrating prognostic relevance. Applications of these markers to urinary testing have been demonstrated.

SUMMARY

Liquid biomarkers show potential in refining prostate cancer management. Future research should aim to integrate these biomarkers into a cohesive framework in line with precision medicine principles.

Elements of liquid biopsies: isolation, analysis, and clinical application in cancer diagnosis to prognosis

INTRODUCTION

The liquid biopsy is a breakthrough in the field of medical diagnostics. It serves as a sentinel that can quietly detect even the subtlest aberrations that indicate the presence of disease. They make it possible to uncover relevant genetic factors of tumors with minimal to no risk to cancer patients. Liquid biopsies allow detailed diagnosis, dynamic treatment monitoring, and accurate prognosis. They are also invaluable in diagnosing other diseases such as infectious diseases and aberrant gene mutations.

AREAS COVERED

The present review undertakes an in-depth analysis of the existing status of liquid biopsy diagnostic tools, focusing on their principal components. Furthermore, the review highlights pertinent and recent research in this field to provide a comprehensive understanding of the current state of this technology and its prospects.

EXPERT OPINION

Despite new and upcoming research in liquid biopsies, multiple areas need to be further explored before the viable transition into the clinical arena. With the advancements in tools such as artificial intelligence and machine learning and the integration of these technologies with liquid biopsies, these challenges are being addressed and will eventually lead to the development of a highly evolved liquid biopsy diagnostic tools.

Recent advances in the use of liquid biopsy for the diagnosis and treatment of lung cancer

INTRODUCTION

In the era of precision medicine, liquid biopsy rapidly emerges as an integrative diagnostic tool to successfully stratify solid tumor patients in accordance with molecular fingerprinting. As the matter of fact, a plethora of analytes may be isolated from liquid biosources supporting the potential application of liquid biopsy in several clinical scenarios. Despite this promising role, liquid biopsy is drastically affected by low abundance of analytes in biological matrix requiring highly sensitive technologies, trained personnel, and optimized diagnostic procedures to successfully administrate this revolutionary diagnostic tool in clinical practice.

AREAS COVERED

This review aims to investigate the recent advancements in technical approaches available to manage liquid biopsy samples, particularly focusing on their application in LC diagnosis and treatment.

EXPERT OPINION

The rapidly evolving scenario of liquid biopsy-based approaches is revolutionizing clinical administration of lung cancer patients. Of note, the integration of genomic, epigenomic, and transcriptomic markers lays the basis for 'comprehensive' molecular fingerprinting of lung cancer patients. Here, the next-generation technologies are fundamental in molecular profiling in diagnostic routine biofluids.

Aggregation-Induced Emission Luminogen: Role in Biopsy for Precision Medicine

Biopsy, including tissue and liquid biopsy, offers comprehensive and real-time physiological and pathological information for disease detection, diagnosis, and monitoring. Fluorescent probes are frequently selected to obtain adequate information on pathological processes in a rapid and minimally invasive manner based on their advantages for biopsy. However, conventional fluorescent probes have been found to show aggregation-caused quenching (ACQ) properties, impeding greater progresses in this area. Since the discovery of aggregation-induced emission luminogen (AIEgen) have promoted rapid advancements in molecular bionanomaterials owing to their unique properties, including high quantum yield (QY) and signal-to-noise ratio (SNR), etc. This review seeks to present the latest advances in AIEgen-based biofluorescent probes for biopsy in real or artificial samples, and also the key properties of these AIE probes. This review is divided into: (i) tissue biopsy based on smart AIEgens, (ii) blood sample biopsy based on smart AIEgens, (iii) urine sample biopsy based on smart AIEgens, (iv) saliva sample biopsy based on smart AIEgens, (v) biopsy of other liquid samples based on smart AIEgens, and (vi) perspectives and conclusion. This review could provide additional guidance to motivate interest and bolster more innovative ideas for further exploring the applications of various smart AIEgens in precision medicine.

Improving the Prognostic and Predictive Value of Circulating Tumor Cell Enumeration: Is Longitudinal Monitoring the Answer?

Circulating tumor cell (CTC) numbers in the blood of cancer patients can indicate the progression and invasiveness of tumors, and their prognostic and predictive value has been repeatedly demonstrated. However, the standard baseline CTC count at the beginning of treatment, while informative, is not completely reliable and may not adequately reflect the state of the disease. A growing number of studies indicate that the long-term monitoring of CTC numbers in the same patient provides more comprehensive prognostic data and should be incorporated into clinical practice, as a factor that contributes to therapeutic decisions. This review describes the current status of CTC enumeration as a prognostic and predictive factor, highlights the shortcomings of current solutions, and advocates for longitudinal CTC analysis as a more effective method of the evaluation of developing disease, treatment efficacy, and the long term-monitoring of the minimal residual disease. As evidenced by the described reports, the longitudinal monitoring of CTCs should provide a better and more sensitive prediction of the course of the disease, and its incorporation in clinical practice should be beneficial.

Label-Free Microfluidic Apheresis of Circulating Tumor Cell Clusters

Screening liters of blood (i.e., apheresis) represents a generalized approach to promote the reliable access to circulating tumor cell clusters (CTCCs), which are known to be highly metastasis-competent, yet ultrarare. However, no existing CTCC sorting technology has demonstrated high throughput, high yield, low shear stress, and minimal blood dilution simultaneously as required in apheresis. Here, a label-free method is introduced termed Precision Apheresis for Non-invasive Debulking of cell Aggregates (PANDA) to continuously isolate CTCCs from undiluted blood to clean buffer through size sorting, processing 1.4 billion cells per second. The cell focusing is optimized within whole blood leveraging secondary transverse flow and margination. The PANDA chip recovers >90% of spiked ≈24 rare HeLa cell clusters from 100 mL undiluted blood samples (equivalent to ≈500 billion blood cells) at 1 L h-1 throughput, with ≤20s device residence time, ≤15 Pa shear stress, and >99.9% return of blood components. The technology lays the groundwork for future routine isolation to increase the recovery of these ultrarare yet clinically significant tumor cell populations from large volumes of blood to advance cancer research, early detection, and treatment.

Microfluidic Applications in Prostate Cancer Research

Prostate cancer is a disease in which cells in the prostate, a gland in the male reproductive system below the bladder, grow out of control and, among men, it is the second-most frequently diagnosed cancer (other than skin cancer). In recent years, prostate cancer death rate has stabilized and, currently, it is the second-most frequent cause of cancer death in men (after lung cancer). Most deaths occur due to metastasis, as cancer cells from the original tumor establish secondary tumors in distant organs. For a long time, classical cell cultures and animal models have been utilized in basic and applied scientific research, including clinical applications for many diseases, such as prostate cancer, since no better alternatives were available. Although helpful in dissecting cellular mechanisms, these models are poor predictors of physiological behavior mainly because of the lack of appropriate microenvironments. Microfluidics has emerged in the last two decades as a technology that could lead to a paradigm shift in life sciences and, in particular, controlling cancer. Microfluidic systems, such as organ-on-chips, have been assembled to mimic the critical functions of human organs. These microphysiological systems enable the long-term maintenance of cellular co-cultures in vitro to reconstitute in vivo tissue-level microenvironments, bridging the gap between traditional cell cultures and animal models. Several reviews on microfluidics for prostate cancer studies have been published focusing on technology advancement and disease progression. As metastatic castration-resistant prostate cancer remains a clinically challenging late-stage cancer, with no curative treatments, we expanded this review to cover recent microfluidic applications related to prostate cancer research. The review includes discussions of the roles of microfluidics in modeling the human prostate, prostate cancer initiation and development, as well as prostate cancer detection and therapy, highlighting potentially major contributions of microfluidics in the continuous march toward eradicating prostate cancer.

Biomarkers for Immunotherapy Efficacy in Advanced Hepatocellular Carcinoma: A Comprehensive Review

Hepatocellular carcinoma (HCC), the most common primary liver malignancy and the sixth most common cancer globally, remains fatal for many patients with inappropriate responses to treatment. Recent advancements in immunotherapy have transformed the treatment landscape for advanced HCC. However, variability in patient responses to immunotherapy highlights the need for biomarkers that can predict treatment outcomes. This manuscript comprehensively reviews the evolving role of biomarkers in immunotherapy efficacy, spanning from blood-derived indicators-alpha-fetoprotein, inflammatory markers, cytokines, circulating tumor cells, and their DNA-to tissue-derived indicators-programmed cell death ligand 1 expression, tumor mutational burden, microsatellite instability, and tumor-infiltrating lymphocytes. The current body of evidence suggests that these biomarkers hold promise for improving patient selection and predicting immunotherapy outcomes. Each biomarker offers unique insights into disease biology and the immune landscape of HCC, potentially enhancing the precision of treatment strategies. However, challenges such as methodological variability, high costs, inconsistent findings, and the need for large-scale validation in well-powered two-arm trial studies persist, making them currently unsuitable for integration into standard care. Addressing these challenges through standardized techniques and implementation of further studies will be critical for the future incorporation of these biomarkers into clinical practice for advanced HCC.

Circulating biomarkers for diagnosis and response to therapies in cancer patients

Cancer presents a significant challenge to global health, driving worldwide concerted efforts to advance early detection, predict therapeutic response, and identify novel targeted therapies. Liquid biopsies emerge as promising avenues for discerning cancer biomarkers, offering less invasive approaches compared to conventional methods. Utilizing increasingly robust technologies, diverse bodily fluids can unveil genetic variants, epigenetic modifications, transcriptional alterations, and metabolomic signatures associated with cancer, thereby furnishing valuable insights for clinical management. This chapter intends to review the sources of cancer-related biomarkers found in circulation, prevalent techniques utilized for their identification, and the potential implications of different biomarker types on the management of cancer. Certain biomarkers currently used in clinical practice will be addressed, as well as potential biomarkers still in the study phase, and the inherent challenges in their practical implementation.

Unveiling the characteristics of D4 and R4 aptamers for their future use in prostate cancer clinical practice

The DNA and RNA aptamers D4 and R4, respectively, emerged from the modification of PC-3 cell-binding aptamer A4. Our objective was to characterize the aptamers in silico and in vitro and begin to identify their target molecules. We represented their structures using computational algorithms; evaluated their binding to several prostate cell lines and their effects on the viability and migration of these cells; and determined their dissociation constant by flow cytometry. We analyzed circulating prostate tumor cells from patients using D4, R4, anti-CD133 and anti-CD44. Finally, the target proteins of both aptamers were precipitated and identified by mass spectrometry to simulate their in silico docking. The aptamers presented similar structures and bound to prostate tumor cells without modifying the cellular parameters studied, but with different affinities. The ligand cells for both aptamers were CD44+, indicating that they could identify cells in the mesenchymal stage of the metastatic process. The possible target proteins NXPE1, ADAM30, and MUC6 need to be further studied to better understand their interaction with the aptamers. These results support the development of new assays to determine the clinical applications of D4 and R4 aptamers in prostate cancer.

Changes of circulating tumor cells expressing CD90 and EpCAM in early-phase of atezolizumab and bevacizumab for hepatocellular carcinoma

Circulating tumor cells (CTCs) are noninvasive biomarkers that can indicate the therapeutic response and prognosis. The study aimed to investigate the cellular characteristics of CTCs focusing on monitoring during atezolizumab and bevacizumab (Atezo-Bev) therapy in patients with hepatocellular carcinoma (HCC). Peripheral blood samples were collected from 10 healthy controls and 40 patients with HCC. CTCs enriched using RosetteSep™ Human CD45 depletion cocktail were analyzed by multiparametric flow cytometry. CTC isolation was based on PanCK(+)CD45(-) cells, and CTCs exhibiting markers CD90, CD133, EpCAM, or vimentin. The total number of CTCs and the number of CTCs expressing CD90, CD133, EpCAM, and vimentin were correlated with the BCLC stage of HCC. The change in total CTC count accurately reflected the initial response to Atezo-Bev therapy. The numbers and mean fluorescence intensity of the CTC subsets expressing CD90 and EpCAM molecules decreased in patients with partial response/stable disease, and increased in patients with progressive disease and were markedly correlated with overall survival. CD90(+) and EpCAM(+) CTCs may be candidate biomarkers for the early prediction of the treatment response and the overall survival of patients with HCC receiving Atezo-Bev therapy.

Circulating tumor cells: advancing personalized therapy in small cell lung cancer patients

Small cell lung cancer (SCLC) is a highly aggressive cancer with a dismal 5-year survival of < 7%, despite the addition of immunotherapy to first-line chemotherapy. Specific tumor biomarkers, such as delta-like ligand 3 (DLL3) and schlafen11 (SLFN11), may enable the selection of more efficacious, novel immunomodulating targeted treatments like bispecific T-cell engaging monoclonal antibodies (tarlatamab) and chemotherapy with PARP inhibitors. However, obtaining a tissue biopsy sample can be challenging in SCLC. Circulating tumor cells (CTCs) have the potential to provide molecular insights into a patient's cancer through a "simple" blood test. CTCs have been studied for their prognostic ability in SCLC; however, their value in guiding treatment decisions is yet to be elucidated. This review explores novel and promising targeted therapies in SCLC, summarizes current knowledge of CTCs in SCLC, and discusses how CTCs can be utilized for precision medicine.

Development of a multigenomic liquid biopsy (PROSTest) for prostate cancer in whole blood

INTRODUCTION

We describe the development of a molecular assay from publicly available tumor tissue mRNA databases using machine learning and present preliminary evidence of functionality as a diagnostic and monitoring tool for prostate cancer (PCa) in whole blood.

MATERIALS AND METHODS

We assessed 1055 PCas (public microarray data sets) to identify putative mRNA biomarkers. Specificity was confirmed against 32 different solid and hematological cancers from The Cancer Genome Atlas (n = 10,990). This defined a 27-gene panel which was validated by qPCR in 50 histologically confirmed PCa surgical specimens and matched blood. An ensemble classifier (Random Forest, Support Vector Machines, XGBoost) was trained in age-matched PCas (n = 294), and in 72 controls and 64 BPH. Classifier performance was validated in two independent sets (n = 263 PCas; n = 99 controls). We assessed the panel as a postoperative disease monitor in a radical prostatectomy cohort (RPC: n = 47).

RESULTS

A PCa-specific 27-gene panel was identified. Matched blood and tumor gene expression levels were concordant (r = 0.72, p < 0.0001). The ensemble classifier ("PROSTest") was scaled 0%-100% and the industry-standard operating point of ≥50% used to define a PCa. Using this, the PROSTest exhibited an 85% sensitivity and 95% specificity for PCa versus controls. In two independent sets, the metrics were 92%-95% sensitivity and 100% specificity. In the RPCs (n = 47), PROSTest scores decreased from 72% ± 7% to 33% ± 16% (p < 0.0001, Mann-Whitney test). PROSTest was 26% ± 8% in 37 with normal postoperative PSA levels (<0.1 ng/mL). In 10 with elevated postoperative PSA, PROSTest was 60% ± 4%.

CONCLUSION

A 27-gene whole blood signature for PCa is concordant with tissue mRNA levels. Measuring blood expression provides a minimally invasive genomic tool that may facilitate prostate cancer management.

Exploiting the metabolic vulnerability of circulating tumour cells

Metastasis has a major part in the severity of disease and lethality of cancer. Circulating tumour cells (CTCs) represent a reservoir of metastatic precursors in circulation, most of which cannot survive due to hostile conditions in the bloodstream. Surviving cells colonise a secondary site based on a combination of physical, metabolic, and oxidative stress protection states required for that environment. Recent advances in CTC isolation methods and high-resolution 'omics technologies are revealing specific metabolic pathways that support this selection of CTCs. In this review, we discuss recent advances in our understanding of CTC biology and discoveries of adaptations in metabolic pathways during their selection. Understanding these traits and delineating mechanisms by which they confer acquired resistance or vulnerability in CTCs is crucial for developing successful prognostic and therapeutic strategies in cancer.

Enhancing the efficiency of lung cancer cell capture using microfluidic dielectrophoresis and aptamer-based surface modification

Metastasis remains a significant cause to cancer-related mortality, underscoring the critical need for early detection and analysis of circulating tumor cells (CTCs). This study presents a novel microfluidic chip designed to efficiently capture A549 lung cancer cells by combining dielectrophoresis (DEP) and aptamer-based binding, thereby enhancing capture efficiency and specificity. The microchip features interdigitated electrodes made of indium-tin-oxide that generate a nonuniform electric field to manipulate CTCs. Following three chip design, scenarios were investigated: (A) bare glass surface, (B) glass modified with gold nanoparticles (AuNPs) only, and (C) glass modified with both AuNPs and aptamers. Experimental results demonstrate that AuNPs significantly enhance capture efficiency under DEP, with scenarios (B) and (C) exhibiting similar performance. Notably, scenario (C) stands out as aptamer-functionalized surfaces resisting fluid shear forces, achieving CTCs retention even after electric field deactivation. Additionally, an innovative reverse pumping method mitigates inlet clogging, enhancing experimental efficiency. This research offers valuable insights into optimizing surface modifications and understanding key factors influencing cell capture, contributing to the development of efficient cell manipulation techniques with potential applications in cancer research and personalized treatment options.

Live cell pool and rare cell isolation using Enrich TROVO system

Although several technologies have been developed to isolate cells of interest from a heterogenous sample, clogging and impaired cell viability limit such isolation. We have developed the Enrich TROVO system as a novel, nonfluidic technology to sort live cells. The TROVO system combines imaging-based cell selection and photo-crosslinking of (gelatin methacrylate) gelMA-hydrogel to capture cells. After capture, cells are released by enzymatic digestion of the hydrogel and then retrieved for downstream analysis or further cell culturing. The system can capture cells with a recovery rate of 48% while maintaining 90% viability. Moreover, TROVO can enrich rare cells 506-fold with 93% efficiency using single step isolation from a 1:104 cell mixture, and can also capture one target cell from 1 million cells, reaching an enrichment ratio of 9128. In addition, 100% purity and 49% recovery rate can be achieved by a following negative isolation process. Compared to existing technologies, the TROVO system is clog-resistant, highly biocompatible, and can process a wide range of sample sizes.

Exploring the Immunological Profile in Breast Cancer: Recent Advances in Diagnosis and Prognosis through Circulating Tumor Cells

This review offers a comprehensive exploration of the intricate immunological landscape of breast cancer (BC), focusing on recent advances in diagnosis and prognosis through the analysis of circulating tumor cells (CTCs). Positioned within the broader context of BC research, it underscores the pivotal role of the immune system in shaping the disease's progression. The primary objective of this investigation is to synthesize current knowledge on the immunological aspects of BC, with a particular emphasis on the diagnostic and prognostic potential offered by CTCs. This review adopts a thorough examination of the relevant literature, incorporating recent breakthroughs in the field. The methodology section succinctly outlines the approach, with a specific focus on CTC analysis and its implications for BC diagnosis and prognosis. Through this review, insights into the dynamic interplay between the immune system and BC are highlighted, with a specific emphasis on the role of CTCs in advancing diagnostic methodologies and refining prognostic assessments. Furthermore, this review presents objective and substantiated results, contributing to a deeper understanding of the immunological complexity in BC. In conclusion, this investigation underscores the significance of exploring the immunological profile of BC patients, providing valuable insights into novel advances in diagnosis and prognosis through the utilization of CTCs. The objective presentation of findings emphasizes the crucial role of the immune system in BC dynamics, thereby opening avenues for enhanced clinical management strategies.

Circulating tumor cells shielded with extracellular vesicle-derived CD45 evade T cell attack to enable metastasis

Circulating tumor cells (CTCs) are precursors of distant metastasis in a subset of cancer patients. A better understanding of CTCs heterogeneity and how these CTCs survive during hematogenous dissemination could lay the foundation for therapeutic prevention of cancer metastasis. It remains elusive how CTCs evade immune surveillance and elimination by immune cells. In this study, we unequivocally identified a subpopulation of CTCs shielded with extracellular vesicle (EVs)-derived CD45 (termed as CD45+ CTCs) that resisted T cell attack. A higher percentage of CD45+ CTCs was found to be closely correlated with higher incidence of metastasis and worse prognosis in cancer patients. Moreover, CD45+ tumor cells orchestrated an immunosuppressive milieu and CD45+ CTCs exhibited remarkably stronger metastatic potential than CD45- CTCs in vivo. Mechanistically, CD45 expressing on tumor surfaces was shown to form intercellular CD45-CD45 homophilic interactions with CD45 on T cells, thereby preventing CD45 exclusion from TCR-pMHC synapse and leading to diminished TCR signaling transduction and suppressed immune response. Together, these results pointed to an underappreciated capability of EVs-derived CD45-dressed CTCs in immune evasion and metastasis, providing a rationale for targeting EVs-derived CD45 internalization by CTCs to prevent cancer metastasis.

Tumor cell-based liquid biopsy using high-throughput microfluidic enrichment of entire leukapheresis product

Circulating Tumor Cells (CTCs), interrogated by sampling blood from patients with cancer, contain multiple analytes, including intact RNA, high molecular weight DNA, proteins, and metabolic markers. However, the clinical utility of tumor cell-based liquid biopsy has been limited since CTCs are very rare, and current technologies cannot process the blood volumes required to isolate a sufficient number of tumor cells for in-depth assays. We previously described a high-throughput microfluidic prototype utilizing high-flow channels and amplification of cell sorting forces through magnetic lenses. Here, we apply this technology to analyze patient-derived leukapheresis products, interrogating a mean blood volume of 5.83 liters from patients with metastatic cancer, with a median of 2,799 CTCs purified per patient. Isolation of many CTCs from individual patients enables characterization of their morphological and molecular heterogeneity, including cell and nuclear size and RNA expression. It also allows robust detection of gene copy number variation, a definitive cancer marker with potential diagnostic applications. High-volume microfluidic enrichment of CTCs constitutes a new dimension in liquid biopsies.

Dielectrophoretic enrichment of live chemo-resistant circulating-like pancreatic cancer cells from media of drug-treated adherent cultures of solid tumors

Due to low numbers of circulating tumor cells (CTCs) in liquid biopsies, there is much interest in enrichment of alternative circulating-like mesenchymal cancer cell subpopulations from in vitro tumor cultures for utilization within molecular profiling and drug screening. Viable cancer cells that are released into the media of drug-treated adherent cancer cell cultures exhibit anoikis resistance or anchorage-independent survival away from their extracellular matrix with nutrient sources and waste sinks, which serves as a pre-requisite for metastasis. The enrichment of these cell subpopulations from tumor cultures can potentially serve as an in vitro source of circulating-like cancer cells with greater potential for scale-up in comparison with CTCs. However, these live circulating-like cancer cell subpopulations exhibit size overlaps with necrotic and apoptotic cells in the culture media, which makes it challenging to selectively enrich them, while maintaining them in their suspended state. We present optimization of a flowthrough high frequency (1 MHz) positive dielectrophoresis (pDEP) device with sequential 3D field non-uniformities that enables enrichment of the live chemo-resistant circulating cancer cell subpopulation from an in vitro culture of metastatic patient-derived pancreatic tumor cells. Central to this strategy is the utilization of single-cell impedance cytometry with gates set by supervised machine learning, to optimize the frequency for pDEP, so that live circulating cells are selected based on multiple biophysical metrics, including membrane physiology, cytoplasmic conductivity and cell size, which is not possible using deterministic lateral displacement that is solely based on cell size. Using typical drug-treated samples with low levels of live circulating cells (<3%), we present pDEP enrichment of the target subpopulation to ∼44% levels within 20 minutes, while rejecting >90% of dead cells. This strategy of utilizing single-cell impedance cytometry to guide the optimization of dielectrophoresis has implications for other complex biological samples.

The effect of magnetic bead size on the isolation efficiency of lung cancer cells in a serpentine microchannel with added cavities

An investigation was conducted to examine the effect of magnetic bead (MB) size on the effectiveness of isolating lung cancer cells using the immunomagnetic separation (IMS) method in a serpentine microchannel with added cavities (SMAC) structure. Carboxylated magnetic beads were specifically conjugated to target cells through a modification procedure using aptamer materials. Cells immobilized with different sizes (in micrometers) of MBs were captured and isolated in the proposed device for comparison and analysis. The study yields significance regarding the clarification of device working principles by using a computational model. Furthermore, an accurate evaluation of the MB size impact on capture efficiency was achieved, including the issue of MB-cell accumulation at the inlet-channel interface, despite it being overlooked in many previous studies. As a result, our findings demonstrated an increasing trend in binding efficiency as the MB size decreased, evidenced by coverages of 50.5%, 60.1%, and 73.4% for sizes of 1.36 μm, 3.00 μm, and 4.50 μm, respectively. Additionally, the overall capture efficiency (without considering the inlet accumulation) was also higher for smaller MBs. However, when accounting for the actual number of cells entering the channel (i.e., the effective capture), larger MBs showed higher capture efficiency. The highest effective capture achieved was 88.4% for the size of 4.50 μm. This research provides an extensive insight into the impact of MB size on the performance of IMS-based devices and holds promise for the efficient separation of circulating cancer cells (CTCs) in practical applications.

Microfluidic devices for precise measurements of cell directionality reveal a role for glutamine during cell migration

Cancer cells that migrate from tumors into surrounding tissues are responsible for cancer dissemination through the body. Microfluidic devices have been instrumental in discovering unexpected features of cancer cell migration, including the migration in self-generated gradients and the contributions of cell-cell contact during collective migration. Here, we design microfluidic channels with five successive bifurcations to characterize the directionality of cancer cell migration with high precision. We uncover an unexpected role for glutamine in epithelial cancer cell orientation, which could be replaced by alfa-keto glutarate but not glucose.

Pre-analytical conditions and implementation of quality control steps in liquid biopsy analysis

Over the last decade, great advancements have been made in the field of liquid biopsy through extensive research and the development of new technologies that facilitate the use of liquid biopsy for cancer patients. This is shown by the numerous liquid biopsy tests that gained clearance by the US Food and Drug Administration (FDA) in recent years. Liquid biopsy has significantly altered cancer treatment by providing clinicians with powerful and immediate information about therapeutic decisions. However, the clinical integration of liquid biopsy is still challenging and there are many critical factors to consider prior to its implementation into routine clinical practice. Lack of standardization due to technical challenges and the definition of the clinical utility of specific assays further complicates the establishment of Standard Operating Procedures (SOPs) in liquid biopsy. Harmonization of laboratories to established guidelines is of major importance to overcome inter-lab variabilities observed. Quality control assessment in diagnostic laboratories that offer liquid biopsy testing will ensure that clinicians can base their therapeutic decisions on robust results. The regular participation of laboratories in external quality assessment schemes for liquid biopsy testing aims to promptly pinpoint deficiencies and efficiently educate laboratories to improve their quality of services. Accreditation of liquid biopsy diagnostic laboratories based on the ISO15189 standard in Europe or by CLIA/CAP accreditation procedures in the US is the best way to achieve the adaptation of liquid biopsy into the clinical setting by assuring reliable results for the clinicians and their cancer patients. Nowadays, various organizations from academia, industry, and regulatory agencies collaborate to set a framework that will include all procedures from the pre-analytical phase and the analytical process to the final interpretation of results. In this review, we underline several challenges in the analysis of circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs) concerning standardization of protocols, quality control assessment, harmonization of laboratories, and compliance to specific guidelines that need to be thoroughly considered before liquid biopsy enters the clinic.

Circulating Tumor Cells as Predictive and Prognostic Biomarkers in Solid Tumors

Circulating tumor cells (CTCs) have emerged as pivotal biomarkers with significant predictive and prognostic implications in solid tumors. Their presence in peripheral blood offers a non-invasive window into the dynamic landscape of cancer progression and treatment response. This narrative literature review synthesizes the current state of knowledge surrounding the multifaceted role of CTCs in predicting clinical outcomes and informing prognosis across a spectrum of solid tumor malignancies. This review delves into the evolving landscape of CTC-based research, emphasizing their potential as early indicators of disease recurrence, metastatic potential, and therapeutic resistance. Moreover, we have underscored the dynamic nature of CTCs and their implications for personalized medicine. A descriptive and critical analysis of CTC detection methodologies, their clinical relevance, and their associated challenges is also presented, with a focus on recent advancements and emerging technologies. Furthermore, we examine the integration of CTC-based liquid biopsies into clinical practice, highlighting their role in guiding treatment decisions, monitoring treatment efficacy, and facilitating precision oncology. This review highlights the transformative impact of CTCs as predictive and prognostic biomarkers in the management of solid tumors by promoting a deeper understanding of the clinical relevance of CTCs and their role in advancing the field of oncology.

Circulating Tumor Cells as a Promising Tool for Early Detection of Hepatocellular Carcinoma

Liver cancer is a significant contributor to the cancer burden, and its incidence rates have recently increased in almost all countries. Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and is the second leading cause of cancer-related deaths worldwide. Because of the late diagnosis and lack of efficient therapeutic modality for advanced stages of HCC, the death rate continues to increase by ~2-3% per year. Circulating tumor cells (CTCs) are promising tools for early diagnosis, precise prognosis, and follow-up of therapeutic responses. They can be considered to be an innovative biomarker for the early detection of tumors and targeted molecular therapy. In this review, we briefly discuss the novel materials and technologies applied for the practical isolation and detection of CTCs in HCC. Also, the clinical value of CTC detection in HCC is highlighted.

Acoustophoretic Characterization and Separation of Blood Cells in Acoustic Impedance Gradients

Single-cell phenotyping based on biophysical properties is a promising tool to distinguish cell types and their response to a given condition, and charting such properties also enables optimization of cell separations. Isoacoustic focusing, where cells migrate to their points of zero acoustic contrast in an acoustic impedance gradient, added the effective acoustic impedance of cells to the directory of biophysical properties that can be utilized to categorize or separate cells. This study investigates isoacoustic focusing in a stop-flow regime and shows how cells migrate towards their isoacoustic point. We introduce a numerical model that we use to estimate the acoustic energy density in acoustic impedance gradient media by tracking particles of known properties, and we investigate the effect of acoustic streaming. From the measured trajectories of cells combined with fluorescence intensity images of the slowly diffusing gradient, we read out the effective acoustic impedance of neutrophils and K562 cancer cells. Finally, we propose suitable acoustic impedance gradients that lead to a high degree separation of neutrophils and K562 cells in a continuous-flow configuration.

Microfluidic Devices for Precise Measurements of Cell Directionality Reveal a Role for Glutamine during Cell Migration

Cancer cells that migrate from tumors into surrounding tissues are responsible for cancer dissemination through the body. Microfluidic devices have been instrumental in discovering unexpected features of cancer cell migration, including the migration in self-generated gradients and the contributions of cell-cell contact during collective migration. Here, we design microfluidic channels with five successive bifurcations to characterize the directionality of cancer cell migration with high precision. We find that the directional decisions of cancer cells moving through bifurcating channels in response to self-generated epidermal growth factor (EGF) gradients require the presence of glutamine in the culture media. A biophysical model helps quantify the contribution of glucose and glutamine to cancer cell orientation during migration in self-generated gradients. Our study uncovers an unexpected interplay between cancer cell metabolism and cancer cell migration studies and may eventually lead to new ways to delay cancer cell invasion.

Three-Dimensional PLGA Nanofiber-Based Microchip for High-Efficiency Cancer Cell Capture

A 3D network capture substrate based on poly(lactic-co-glycolic acid) (PLGA) nanofibers was studied and successfully used for high-efficiency cancer cell capture. The arc-shaped glass micropillars were prepared by chemical wet etching and soft lithography. PLGA nanofibers were coupled with micropillars by electrospinning. Given the size effect of the microcolumn and PLGA nanofibers, a three-dimensional of micro-nanometer spatial network was prepared to form a network cell trapping substrate. After the modification of a specific anti-EpCAM antibody, MCF-7 cancer cells were captured successfully with a capture efficiency of 91%. Compared with the substrate composed of 2D nanofibers or nanoparticles, the developed 3D structure based on microcolumns and nanofibers had a greater contact probability between cells and the capture substrate, leading to a high capture efficiency. Cell capture based on this method can provide technical support for rare cells in peripheral blood detection, such as circulating tumor cells and circulating fetal nucleated red cells.

Detection and Molecular Characterization of Circulating Tumour Cells: Challenges for the Clinical Setting

Over the last decade, liquid biopsy has gained much attention as a powerful tool in personalized medicine since it enables monitoring cancer evolution and follow-up of cancer patients in real time. Through minimally invasive procedures, liquid biopsy provides important information through the analysis of circulating tumour cells (CTCs) and circulating tumour-derived material, such as circulating tumour DNA (ctDNA), circulating miRNAs (cfmiRNAs) and extracellular vehicles (EVs). CTC analysis has already had an important impact on the prognosis, detection of minimal residual disease (MRD), treatment selection and monitoring of cancer patients. Numerous clinical trials nowadays include a liquid biopsy arm. CTC analysis is now an exponentially expanding field in almost all types of solid cancers. Functional studies, mainly based on CTC-derived cell-lines and CTC-derived explants (CDx), provide important insights into the metastatic process. The purpose of this review is to summarize the latest findings on the clinical significance of CTCs for the management of cancer patients, covering the last four years. This review focuses on providing a comprehensive overview of CTC analysis in breast, prostate and non-small-cell lung cancer. The unique potential of CTC single-cell analysis for understanding metastasis biology, and the importance of quality control and standardization of methodologies used in this field, is also discussed.

Circulating Tumor Cells in Cancer Diagnostics and Prognostics by Single-Molecule and Single-Cell Characterization

Circulating tumor cells (CTCs) represent an interesting source of biomarkers for diagnosis, prognosis, and the prediction of cancer recurrence, yet while they are extensively studied in oncobiology research, their diagnostic utility has not yet been demonstrated and validated. Their scarcity in human biological fluids impedes the identification of dangerous CTC subpopulations that may promote metastatic dissemination. In this Perspective, we discuss promising techniques that could be used for the identification of these metastatic cells. We first describe methods for isolating patient-derived CTCs and then the use of 3D biomimetic matrixes in their amplification and analysis, followed by methods for further CTC analyses at the single-cell and single-molecule levels. Finally, we discuss how the elucidation of mechanical and morphological properties using techniques such as atomic force microscopy and molecular biomarker identification using nanopore-based detection could be combined in the future to provide patients and their healthcare providers with a more accurate diagnosis.

Dielectrophoresis-Based SERS Sensors for the Detection of Cancer Cells in Microfluidic Chips

The detection of freely circulating cancer cells (CTCs) is one of the greatest challenges of modern medical diagnostics. For several years, there has been increased attention on the use of surface-enhanced Raman spectroscopy (SERS) for the detection of CTCs. SERS is a non-destructive, accurate and precise technique, and the use of special SERS platforms even enables the amplification of weak signals from biological objects. In the current study, we demonstrate the unique arrangement of the SERS technique combined with the deposition of CTCs cells on the surface of the SERS platform via a dielectrophoretic effect. The appropriate frequencies of an alternating electric field and a selected shape of the electric field can result in the efficient deposition of CTCs on the SERS platform. The geometry of the microfluidic chip, the type of the cancer cells and the positive dielectrophoretic phenomenon resulted in the trapping of CTCs on the surface of the SERS platform. We presented results for two type of breast cancer cells, MCF-7 and MDA-MB-231, deposited from the 0.1 PBS solution. The limit of detection (LOD) is 20 cells/mL, which reflects the clinical potential and usefulness of the developed approach. We also provide a proof-of-concept for these CTCs deposited on the SERS platform from blood plasma.