Isolation Of Circulating Tumor Cells Research Articles

Current biological implications and clinical relevance of metastatic circulating tumor cells.

Metastatic disease and cancer recurrence are the primary causes of cancer-related deaths. Circulating tumor cells (CTCs) and disseminated tumor cells (DTCs) are the driving forces behind the spread of cancer cells. The emergence and development of liquid biopsy using rare CTCs as a minimally invasive strategy for early-stage tumor detection and improved tumor management is a promising advancement in recent years. However, before blood sample analysis and clinical translation, precise isolation of CTCs from patients' blood based on their biophysical properties, followed by molecular identification of CTCs using single-cell multi-omics technologies is necessary to understand tumor heterogeneity and provide effective diagnosis and monitoring of cancer progression. Additionally, understanding the origin, morphological variation, and interaction between CTCs and the primary and metastatic tumor niche, as well as and regulatory immune cells, will offer new insights into the development of CTC-based advanced tumor targeting in the future clinical trials.

Abstract A003: CD45 positive circulating tumor cells as a prognostic marker in prostate cancer

Abstract Prostate cancer is one of the most common types of cancer among male patients worldwide, making early diagnosis and effective treatment crucial for improving patient survival rates. In this regard, circulating tumor cells (CTCs) have garnered attention as an important biomarker for cancer staging and monitoring treatment response. In prostate cancer, CTCs are typically identified as keratin+/CD45- cells, with additional markers such as PSA or PSMA also being used. The conventional CTC identification way have dismissed CD45+/keratin+ double-positive cells as artifacts by nonspecific binding during the staining process. However, recent studies have reported the presence of CD45+/keratin+ CTCs in various types of cancers, highlighting metastatic potential and their ability to evade the immune system. These findings require re- examination of the role for the double positive CTCs. Therefore, this study aimed to identify the presence of CD45+ CTCs in prostate cancer and to assess their clinical significance. Blood samples were collected from 80 prostate cancer patients, followed by unbiased isolation of CTCs, which were stained using PSA, keratin, and CD45. The detected CTCs were categorized based on CD45 expression, and the clinical relevance of each group was validated using patient information. Through this study, we aimed to confirm whether the CD45+ CTCs can be a clinical indicator in prostate cancer. The results revealed that CD45+ CTCs accounted for 90% of all detected CTCs, likely due to their high immune evasion capabilities. Additionally, in 17% of the patients, only CD45+ CTCs were detected, indicating the potential to expand CTC detection even in patients where CTCs were previously undetected using conventional criteria. The number of CD45+ CTCs was significantly higher in patients with progressive disease compared to those with complete or partial response, showing greater statistical significance than analyses using CD45- CTCs. Furthermore, the number of PSA+ CTCs was closely linked to changes in plasma PSA levels, suggesting they could be used as a supporting marker to enhance the accuracy of current plasma PSA tests. These findings indicate that CD45+ CTCs in prostate cancer are not merely artifacts of nonspecific binding but are indeed meaningful cells closely related to cancer progression. This study suggests that CD45+ CTCs have the potential to be utilized as a prognostic biomarker in prostate cancer. By including CD45+ CTCs, which were previously overlooked in conventional CTC analysis methods, more sensitive and accurate cancer monitoring could be achieved. In-depth future studies on the clinical applicability of CD45+ CTCs could significantly contribute to predicting prognosis and developing personalized treatment strategies for prostate cancer patients. Citation Format: Hyeongjung Woo, Woon-Hae Kim, Hyun Young Shin, Hyerin Jung, Hyung Ho Lee, Minseok S. Kim, Jae Young Joung. CD45 positive circulating tumor cells as a prognostic marker in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A003.

Abstract A031: Harnessing the potential of circulating tumour cells for precision diagnostics via multiplexed imaging of the levels and subcellular localizations of over 50 cell identity, state and signaling markers per cell

Abstract Due to their longitudinal accessibility through liquid biopsy, circulating tumour cells (CTCs) hold huge potential as sources of molecular information capable of underpinning precision diagnostics in cancer. Yet key methodological limitations have thus far constrained the practical utility of CTCs as diagnostic analytes, including: a) reliance on positive CTC selection strategies that can bias against distinctive CTC subpopulations (e.g. low EpCAM, low size, low density), and; b) standard fluorescence imaging methods that capture only 4-6 molecular markers per cell. Since 3-4 markers are required to identify CTCs with even moderate confidence, such low marker plexity acutely restricts derivation of additional molecular insights about the cellular states and molecular signals that may be driving disease. Yet these insights are essential to guide selection of optimal therapies, to adapt therapeutic strategies as cycles of resistance arise, and even to stratify patients to the trials needed to expand the therapeutic arsenal. To overcome these challenges and harness the potential of CTCs for precision diagnostics, we have developed a comprehensive pipeline for CTC isolation, storage and batch processing via multiplexed immunofluorescence imaging of 50+ molecular markers per cell. These markers illuminate CTC identity, state (epithelial vs mesenchymal vs stemness), fate (proliferation, death, senescence) and signalling (spanning ∼10 alternate ‘driver’ signalling pathways), providing truly unprecedented molecular insights per CTC, across heterogeneous CTC populations, and regarding potential therapeutic targets. Downstream single-cell quantitative image analyses enable robust but adaptable computational parsing of CTC identity, removing false-positive and false-negative instances otherwise resulting from standard 4-plex CTC definitions (e.g. DAPI, CD45, EpCAM, pan-Cytokeratin) and complementing our upstream use of negative selection methods that capture the full, unbiased diversity of CTCs. The remaining 40+ markers facilitate integrated analyses of relationships between CTC state, fate and signalling pathways, capturing not only protein and phospho-protein expression levels per cell, but also variations in subcellular localisation that constitute additional layers of functional regulation not captured by most omics methods. Excitingly, when combined with machine learning, our approach can discern therapy- resistant cell subpopulations with over 98% accuracy in models of prostate cancer therapy resistance. We are now assessing CTC diversity across patients ranging from treatment naïve to advanced castrate-resistance prostate cancers. Overall, our unique high-plexity analysis now enables interrogation of detailed states, signals and dependencies in each patient CTC, providing the foundations for next-generation precision diagnostics to continuously match individual patients to optimal therapies at each stage of their disease journey. We believe this marks a significant step towards harnessing the true potential of CTCs for precision diagnostics. Citation Format: John G Lock, Tim J Mann, Ye Zheng, Tanzila Khan, Daniel Neumann, Alexander James, Therese Becker, Tara Roberts. Harnessing the potential of circulating tumour cells for precision diagnostics via multiplexed imaging of the levels and subcellular localizations of over 50 cell identity, state and signaling markers per cell [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A031.

Measurable morphological features of single circulating tumor cells in selected solid tumors-A pilot study.

Liquid biopsies developed into a range of sensitive technologies aiming to analyze for example, circulating tumor cells (CTCs) in peripheral blood, which significantly deepens understanding of the metastatic process. Nevertheless, examination of CTCs is mostly limited to their enumeration and usually only 2-3 markers-based phenotyping, not offering yet sufficient insight into their biology. In contrast, quantitative analysis of their morphological details might extend our knowledge about dissemination and even improve CTC isolation or label-free identification methods dependent on their physical features such as size, and deformability. Current study was conducted to describe CTCs' and their size, shape, presence of protrusions, and micronuclei across various types of cancers (lung, n = 29; ovarian, n = 24, breast, n = 54; and prostate, n = 33). Epithelial (pan-keratins), mesenchymal (vimentin), and two exclusion markers were used to identify CTCs and classify them into four epithelial and epithelial-mesenchymal transition-related phenotypes using standardized and throughput method, imaging flow cytometry. The morphological characteristics of CTCs, including their nuclei, such as circularity, the maximum, and minimum diagonal values were determined using an open-source software QuPath. On average, detected CTCs (n = 1156) were larger, and more irregular in shape compared to leukocytes/endothelial cells (n = 400). Epithelial and mesenchymal CTCs had the largest (median = 18.2 μm) and the smallest diameter (median = 10.4 μm), respectively. In terms of cancer-specific variations, the largest CTCs were identified in lung cancer, whereas the smallest-in prostate and breast cancers. Epithelial CTCs and those negative for both epithelial and mesenchymal markers exhibited the highest degree of elongation, whereas mesenchymal CTCs were the most irregular in shape. Protrusions and micronuclei were observed extremely rarely within CTCs of breast and prostate cancer (0.6%-0.8% of CTCs). Micronuclei were observed only in epithelial and epithelial-mesenchymal CTCs. This study underscores the significant variability in the morphological features of CTCs in relation to their phenotypic classification or even the particular organ of origin, potentially influencing for example, size-dependent CTC isolation methods. It demonstrates for the first time the morphological measurements of CTCs undergoing epithelial-mesenchymal transition, and some specific morphological details (i.e., protrusions, micronuclei) within CTCs in general.

Nanoparticles as a novel key driver for the isolation and detection of circulating tumour cells

Circulating tumour cells (CTCs), derived from primary tumours, play a pivotal role in cancer metastasis by migrating into the peripheral bloodstream. These cells are paramount in clinical research, serving as early diagnostic markers for metastatic cancer. Analysing CTC counts and their biomarker characteristics can provide invaluable insights into tumour identification, profiling, and metastatic capabilities. However, the rarity and diverse nature of CTCs in the bloodstream present significant challenges to their isolation and detection, especially in the initial stages of metastasis. Recent advancements in nanotechnology have led to the development of innovative CTC separation and detection methods. This review focuses on applying nanoparticles, nanomaterials, and microfluidic platforms to simplify the isolation and detection of CTCs. The infusion of nanotechnology in this field marks a crucial turning point, enabling the necessary progress to advance CTC research.

Effective Boundary Correction for Deterministic Lateral Displacement Microchannels to Improve Cell Separation: A Numerical and Experimental Study.

Particle separation and sorting techniques based on microfluidics have found extensive applications and are increasingly gaining prominence. This research presents the design and fabrication of a microfluidic device for separating cells using deterministic lateral displacement (DLD), enabling accuracy and continuity while being size-based. Nevertheless, it remains demanding, to completely reverse the detrimental effects of the boundaries that disturb the fluidic flow in the channel and reduce particle separation efficiency. This study introduces a novel approach to enhance the boundary structure of channels. By using this design, separation efficiency is boosted, and the fluid behavior around the walls is improved. The boundary correction (BC) enhances the operation of the microchannel and is very effective in microchannels. With boundary correction, the device exhibited improved separation efficiencies, but in its absence, separation efficiencies dropped. The collected microscopic images of the isolation of prostate cancer cell lines and red blood cells revealed promising outcomes. The efficiency of circulating tumor cell (CTC) throughput in the microfluidic channel, quantified as the ratio or proportion of tumor cells exiting the channel to cells entering it, exceeds 93%. Moreover, the efficiency of CTC isolation, expressed as the proportion of tumor cells from the upper outlet of the microfluidic channel to all cells, is over 89%. Additionally, the efficiency of red blood cell isolation, evaluated as the ratio of red blood cells from the lower outlet of the microfluidic channel to all cells, surpasses 77%. While using the same DLD separator without boundary correction reduced the separation efficiency by around 5%.

Circulating Tumor Cells: Origin, Role, Current Applications, and Future Perspectives for Personalized Medicine.

Circulating tumor cells (CTCs) currently represent a revolutionary tool offering unique insights for the evaluation of cancer progression, metastasis, and response to therapies. Indeed, CTCs, upon detachment from primary tumors, enter the bloodstream and acquire a great potential for their use for personalized cancer management. In this review, we describe the current understanding of and advances in the clinical employment of CTCs. Although considered rare and fleeting, CTCs are now recognized as key players favoring the development of cancer metastasis and disease recurrence, particularly in malignant melanoma, lung, breast, and colorectal cancer patients. To date, the advancements in technology and the development of several successful approaches, also including immunomagnetic enrichment allow for a reliable and reproducible detection and characterization of CTCs. Those innovative methodologies improved the isolation, quantification, and characterization of CTCs from the blood of cancer patients, providing extremely useful evidence and new insights into the nature of the tumor, its epithelial/mesenchymal profile, and its potential resistance to therapy. In fact, in addition to their prognostic and predictive value, CTCs could serve as a valuable instrument for real-time monitoring of treatment response and disease recurrence, facilitating timely interventions and thus improving patient outcomes. However, despite their potential, several challenges hinder the widespread clinical utility of CTCs: (i) CTCs' rarity and heterogeneity pose technical limitations in isolation and characterization, as well as significant hurdles in their clinical implementation; (ii) it is mandatory to standardize CTC detection methods, optimize the sample processing techniques, and integrate them with existing diagnostic modalities; and (iii) the need for the development of new techniques, such as single-cell analysis platforms, to enhance the sensitivity and specificity of CTC detection, thereby facilitating their integration into routine clinical practice. In conclusion, CTCs represent a potential extraordinary tool in cancer diagnostics and therapeutics, offering unprecedented opportunities for personalized medicine and precision oncology. Moreover, their ability to provide real-time insights into tumor biology, treatment response, and disease progression underlines a great potential for their clinical application to improve patients' outcomes and advance our understanding of cancer biology.

Recent advances in responsive isolation, release and clinical application of circulating tumor cells

Circulating tumor cells (CTCs) are cells that dissociate from the tumor tissue and enter the lymphatic system or bloodstream with close association with tumor metastasis and recurrence. CTCs contain complete pathological information, which can be extracted by isolation, enrichment, and analysis of the CTCs to guide cancer diagnosis and treatment, thereby significantly improving the monitoring efficiency and prognosis of cancer. Compared with tissue biopsy, liquid biopsy with CTCs as a biomarker enables specific and dynamic detection of tumor growth with a less painful experience. For detection of CTCs, the cells must be captured from body fluids, followed then by their release and enrichment. This review summaries the latest research progress in responsive isolation of CTCs (e.g. with light, dielectrophoresis, acoustophoresis and magnetophoresis), chemical isolation (specific molecules and topological structure) and responsive release (e.g., light, electric, thermal, pH, enzyme responsiveness, and substrates break). Responsive isolation utilizes the differences in physical properties between CTCs and blood cells, while chemical isolation utilizes specific recognition mechanisms to capture the CTCs. These techniques result in low cell damage with a high specificity to facilitate further analysis. Currently, CTC detection has been applied for early diagnosis and prognostic assessment of multiple cancers including lung cancer, liver cancer, colorectal cancer, and prostate cancer.

A Novel Size-Based Centrifugal Microfluidic Design to Enrich and Magnetically Isolate Circulating Tumor Cells from Blood Cells through Biocompatible Magnetite-Arginine Nanoparticles.

This paper presents a novel centrifugal microfluidic approach (so-called lab-on-a-CD) for magnetic circulating tumor cell (CTC) separation from the other healthy cells according to their physical and acquired chemical properties. This study enhances the efficiency of CTC isolation, crucial for cancer diagnosis, prognosis, and therapy. CTCs are cells that break away from primary tumors and travel through the bloodstream; however, isolating CTCs from blood cells is difficult due to their low numbers and diverse characteristics. The proposed microfluidic device consists of two sections: a passive section that uses inertial force and bifurcation law to sort CTCs into different streamlines based on size and shape and an active section that uses magnetic forces along with Dean drag, inertial, and centrifugal forces to capture magnetized CTCs at the downstream of the microchannel. The authors designed, simulated, fabricated, and tested the device with cultured cancer cells and human cells. We also proposed a cost-effective method to mitigate the surface roughness and smooth surfaces created by micromachines and a unique pulsatile technique for flow control to improve separation efficiency. The possibility of a device with fewer layers to improve the leaks and alignment concerns was also demonstrated. The fabricated device could quickly handle a large volume of samples and achieve a high separation efficiency (93%) of CTCs at an optimal angular velocity. The paper shows the feasibility and potential of the proposed centrifugal microfluidic approach to satisfy the pumping, cell sorting, and separating functions for CTC separation.

A comparative study of circulating tumor cell isolation and enumeration technologies in lung cancer.

Circulating tumor cells (CTCs) have potential as diagnostic, prognostic, and predictive biomarkers in solid tumors. Despite Food and Drug Administration (FDA) approval of CTC devices in various cancers, the rarity and heterogeneity of CTCs in lung cancer make them technically challenging to isolate and analyze, hindering their clinical integration. Establishing a consensus through comparative analysis of different CTC systems is warranted. This study aimed to evaluate seven different CTC enrichment methods across five technologies using a standardized spike-in protocol: the CellMag™ (EpCAM-dependent enrichment), EasySep™ and RosetteSep™ (blood cell depletion), and the Parsortix® PR1 and the new design Parsortix® Prototype (PP) (size- and deformability-based enrichment). The Parsortix® systems were also evaluated for any differences in recovery rates between cell harvest versus in-cassette staining. Healthy donor blood (5 mL) was spiked with 100 fluorescently labeled EpCAMhigh H1975 cells, processed through each system, and the isolation efficiency was calculated. The CellMag™ had the highest recovery rate (70 ± 14%), followed by Parsortix® PR1 in-cassette staining, while the EasySep™ had the lowest recovery (18 ± 8%). Additional spike-in experiments were performed with EpCAMmoderate A549 and EpCAMlow H1299 cells using the CellMag™ and Parsortix® PR1 in-cassette staining. The recovery rate of CellMag™ significantly reduced to 35 ± 14% with A549 cells and 1 ± 1% with H1299 cells. However, the Parsortix® PR1 in-cassette staining showed cell phenotype-independent and consistent recovery rates among all lung cancer cell lines: H1975 (49 ± 2%), A549 (47 ± 10%), and H1299 (52 ± 10%). Furthermore, we demonstrated that the Parsortix® PR1 in-cassette staining method is capable of isolating heterogeneous single CTCs and cell clusters from patient samples. The Parsortix® PR1 in-cassette staining, capable of isolating different phenotypes of CTCs as either single cells or cell clusters with consistent recovery rates, is considered optimal for CTC enrichment for lung cancer, albeit needing further optimization and validation.

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.

High-throughput viable circulating tumor cell isolation using tapered-slit membrane filter-based chipsets in the differential diagnosis of ovarian tumors.

To evaluate the diagnostic performance of circulating tumor cells (CTCs) using tapered-slit membrane filter (TSF)-based chipsets for the differential diagnosis of adnexal tumors. A total of 230 women with indeterminate adnexal tumors were prospectively enrolled. The sensitivity, specificity, and accuracy of the CTC-detecting chipsets were analyzed according to postoperative pathological results and compared with those of cancer antigen (CA)-125 and imaging tests. Eighty-one (40.3%) benign tumors, 31 (15.4%) borderline tumors, and 89 (44.3%) ovarian cancers were pathologically confirmed. The sensitivity, specificity, and accuracy of CTC-detecting chipsets (75.3%, 58.0%, and 67.1%) for differentiating ovarian cancer from benign tumors were similar to CA-125 (78.7%, 53.1%, and 66.5%), but lower than CT/MRI (94.2%, 77.9%, and 86.5%). "CTC or CA125" showed increased sensitivity (91.0%) and "CTC and CA-125" revealed increased specificity (77.8%), comparable to CT/MRI. CTC detection rates in stage I/II and stage III/IV ovarian cancers were 69.6% and 81.4%, respectively. The sensitivity to detect high-grade serous (HGS) cancer from benign tumors (84.6%) was higher than that to detect non-HGS cancers (68.0%). Although the diagnostic performance of the TSF platform to differentiate between ovarian cancer and benign tumors did not yield significant results, the combination of CTC and CA-125 showed promising potential in the diagnostic accuracy of ovarian cancer.

Molecular profiling using next generation sequencing with high-purity enrichment of circulating tumor cells.

e15054 Background: In the field of liquid biopsy, coupled with next generation sequencing (NGS), circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) can serve as an alternative substrate to tumor tissue for mutation detection and companion diagnostic purpose. Emerging evidence suggests that complementary sequential CTCs and ctDNA profiling offers promising benefits for prognosis and treatment. In contrast to well-established ctDNA extraction methods, the process of isolation of intact CTCs for NGS analysis has not yet been fully elucidated. Here we show that isolation and harvesting of viable CTCs using CytoGen's Smart Biopsy™ System achieves high CTC purity for NGS analysis in breast cancer and non-small cell lung cancer (NSCLC). Methods: Targeted panel sequencing for CTC was developed to detect representative mutated genes using the Oncomine™ Comprehensive Assay Plus (501 genes) and the Oncomine™ Pan-Cancer Cell-Free Assay (52 genes). Analytical validation was performed with breast cancer cells MDA-MB-231 (50 to 5 cells) and NSCLC cells H358 (10 and 5 cells) which were spiked into 5 mL of healthy blood to mimic CTCs. CytoGen's Smart Biopsy™ System was applied to isolate the CTCs. Subsequently, CD45 depletion and whole genome amplification were performed. Sequencing was performed on Ion S5™ XL Systems using an Ion 550™ chip kit. The sequencing data were then analyzed using the Ion Torrent software with the default configurations. Results: As a result of targeted panel sequencing with Oncomine™ Comprehensive Assay Plus, representative breast cancer mutation genes (BRAF, KRAS, TP53, NF2 and NOTCH3) were detected in at least 20 MDA-MB-231 cells. In the results using Oncomine™ Pan-Cancer Cell-Free Assay, mutated genes (BRAF, KRAS and TP53) were successfully detected in as few as 5 MDA-MB-231 cells and, in addition, KRAS mutation was detected even with only 5 H358 cells. These results suggest that CytoGen's Smart Biopsy™ System could be applied to detect representative mutated genes in clinical breast cancer and NSCLC patient samples with detection technology that require high sensitivity and specificity. Conclusions: Molecular analysis of CTCs is a challenge since CTCs are very rare in the blood and there are technical limitations in isolating CTCs with sufficient purity for NGS analysis. In this study, we developed the process for NGS analysis on very small number of high-purity CTCs using CytoGen's Smart Biopsy™ System. Taken together with the results from our ongoing clinical trials, this process could provide information for the diagnosis and appropriate treatment of breast cancer and NSCLC patients.

Platelet-mediated circulating tumor cell evasion from natural killer cell killing via immune checkpoint CD155-TIGIT.

e14552 Background: Circulating tumor cells (CTCs) are precursors of cancer metastasis. However, how CTCs evade immunosurveillance during hematogenous dissemination remains unclear. The interaction between platelets and CTCs is the most extensively studied of all blood cells, and it is well known that CTCs are surrounded by platelets, which form microplots on their surface and play a crucial role in cancer metastasis. The precise mechanisms platelets employ to contribute to CTC immune evasion have not been fully elucidated. Our previous single-cell RNA sequencing data indicated high expression of platelet-related genes in CTCs. Here, our study demonstrated that platelet adhesion to CTCs is prevalent in multiple cancers and is indispensable for CTCs metastasis. Methods: CTC isolation was performed by our self-established ChimeraX-i120 platform. CTC-platelet adhesions were identified by single-cell RNA sequencing and multiplex immunofluorescence of blood samples from multiple cancer types. The cytotoxicity of natural killer (NK) cells was assessed by the reduction in tumor cell numbers measured using the xCELLigence system. In vitro and ex vivo co-culture systems were established by using platelets and NK cells isolated from the peripheral blood of patients for direct or indirect co-culturing with cell lines and patient-derived organoids (PDOs). The effects of platelets and NK cells on metastasis and immune responses were investigated in vivo by utilizing mouse models. Results: Clinically, CTC-platelet aggregates were associated with significantly shorter progression-free survival and overall survival in hepatocellular carcinoma patients. In vitro, ex vivo, and in vivo assays demonstrated direct platelet adhesions gifted cancer cells with an evasive ability from NK cell killing by upregulating inhibitory checkpoint CD155, therefore facilitating distant metastasis. Mechanistically, CD155 was transcriptionally regulated by the FAK/JNK/c-Jun cascade in a platelet contact-dependent manner. Further competition assays and cytotoxicity experiments revealed that CD155 on CTCs inhibited NK cell cytotoxicity only by engaging with immune receptor TIGIT, but not CD96 and DNAM1, another two receptors for CD155. Interrupting the CD155-TIGIT interactions with a TIGIT antibody restored NK cell immunosurveillance on CTCs and markedly attenuated tumor metastasis. Conclusions: Our results demonstrated CTC evasion from NK cell-mediated innate immunosurveillance mainly via immune checkpoint CD155-TIGIT, potentially offering an immunotherapeutic strategy for eradicating CTCs.

Investigating the Influence of Preoperative Trans Arterial Embolization (TAE) and Predictive Potential of Circulating Tumor Cells (CTCs) in Prognosis of Hepatocellular Carcinoma

IntroductionCirculating Tumor Cells are a promising biomarker in many malignancies. CTC dissemination during the operative procedure can lead to disease recurrence. The effect of preoperative Transarterial Embolization on the release of CTCs and miRNA panels and oncological outcomes in large hepatocellular carcinomas has been evaluated. Materials and MethodsThe study included non-metastatic HCC >5cm in size, that were completely resected after TAE (n=10). Blood was collected pre-TAE, post-TAE, postoperative (day 2,30 and 180) and analyzed for the presence of CTC and miRNA (miR885-5p, miR22-3p, miR 642b-5p). The samples were subjected to CTC enrichment, isolation and staining using the markers CD45, EpCAM and Cytokeratin (CK). The data was analyzed using Gene Expression Suite software. ResultsThe CTC enumeration resulted in three groups: Group 1- CTC present at both Pre TAE and postoperative day 30 (n=4), Group 2- CTC present Pre-TAE and clearing at postoperative day 30 (n=2), Group 3- No CTC detected at any stages (n=3). Group 2 patients had better survival as compared to the other groups. Downregulation of miRNA 22-3p also had favourable prognostic implications. ConclusionWhile preoperative TAE does not seem to impact CTC shedding, CTC clearance may prove to be a valuable biomarker in prognosticating HCC. A larger study to evaluate the significance of CTCs as a prognostic marker is warranted to further evaluate these findings.

Abstract PO4-13-08: Mechanical conditioning (MeCo) score is higher in circulating tumor cells (CTCs) compared to primary tumors in early-stage breast cancer and even higher in metastases compared to CTCs in metastatic breast cancer

Abstract Background: The mechanical conditioning (MeCo) score is a gene expression signature that is acquired early by cancer cells in the primary breast tumor and is reflective of their responsiveness to matrix stiffness (fibrotic-like matrix rigidity). Further, chromatin remodeling in response to stiffness allows cancer cells to retain their aggressive features even in the absence of mechanical stimulation by the primary tumor microenvironment, for instance, during their dissemination through the circulation in metastasis. Importantly, patients who have high MeCo score tumors are at higher risk of developing metastatic breast cancer, compared to low MeCo scores (p< 0.0001; HR=2.2, 95%CI 1.7-2.7; Watson et al 2021, PMID: 34192535). Moreover, circulating tumor cells (CTCs) are associated with higher rate of metastatic dissemination, making CTC detection in the circulation of breast cancer patients a significant prognostic biomarker for breast cancer metastasis. Beyond their enumeration per blood volume units, specific prognostic features of CTCs are not fully explored. We sought to determine whether, compared to primary tumors, CTCs retain high MeCo scores and whether these scores are maintained during late-stage breast cancer in the metastatic sites. Methods: CTCs were isolated from peripheral blood of two patient cohorts: stage II-III breast cancer patients using immunomagnetic enrichment/FACS methodology (Lang et al 2018, PMID: 29868978) and of metastatic breast cancer patients using ANGLE Parsortix microfluidics system (Ring et al 2022, PMID: 35000083). Gene expression profiling using RNA-seq was performed in CTCs and in matching primary tumors (PT) and metastases (MET) for the early-stage and late-stage cohorts, respectively. A quantile normalization approach was used to allow comparison across cohorts. MeCo scores were computed for all samples as per Watson et al 2021. Wilcoxon matched-pairs signed rank test was performed for comparison of MeCo scores from matching samples within each cohort; Mann-Whitney unpaired test was used to compared MeCo scores of CTCs across cohorts. Results: In 12 pairs of early-stage breast cancer patient CTCs and PT, MeCo scores of CTCs were significantly higher than their matched PTs (p=0.026). Furthermore, in 26 pairs of metastatic patient’s CTCs and MET, MeCo scores of METs were significantly higher than matching CTCs (p=0.0004). MeCo scores of CTCs were similar between early- and late-stage breast cancer despite differing CTC isolation strategies (epitope-dependent and microfluidics size gradient). 98% of genes in the MeCo score were present in the evaluable CTC, MET and PT samples. Conclusions: Our results show that the MeCo score is higher in CTCs compared to PTs and in METs compared to CTCs in early- and late-stage breast cancer, respectively. Therefore, the MeCo score is progressively higher throughout the metastatic cascade in breast cancer. These findings demonstrate that mechanical conditioning is retained during metastatic progression, even as cancer cells transition through the circulation where the initial induction by matrix stiffness is lost. Further, these findings support that cancer cells with higher MeCo scores are more competent with–and potentially selected for by–metastatic progression. Importantly, these findings provide a novel feature of CTCs, mechanical conditioning (MeCo), which is associated with higher capacity for metastasis. Further, since the CTC MeCo score is elevated even in early-stage breast cancer, it could provide, in addition to CTC enumeration, a potential prognostic tool to predict metastatic risk in breast cancer patients. Citation Format: Gus Mouneimne, Adam Watson, Adam Grant, Daniel Campo, Alexander Ring, Pushpinder Bains, Julie Lang. Mechanical conditioning (MeCo) score is higher in circulating tumor cells (CTCs) compared to primary tumors in early-stage breast cancer and even higher in metastases compared to CTCs in metastatic breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-13-08.

Research progress of cell membrane biomimetic nanoparticles for circulating tumor cells.

Early detection of cancer is crucial to reducing fatalities and improving patient outcomes. Metastasis is the first stage of aggressive cancers, often occurring before primary lesions can be seen. It occurs when cancerous cells disseminate to distant, non-malignant organs through the bloodstream, known as circulating tumor cells (CTCs). CTCs, or cancer tumor cells, are valuable indicators for predicting treatment response, metastasis progression, and disease progression. However, they are primarily used for research due to challenges like heterogeneity, separation from blood, and lack of clinical validation. Only a few methods have been approved for clinical use. One area of research is the isolation and identification of CTCs, which could significantly impact early cancer detection and prognosis. Current technologies using whole-blood samples use size, immunoaffinity, and density approaches, along with positive and negative enrichment techniques. Surface modification of nanomaterials is important for effective cancer therapies because it improves their ability to target and reduces interactions with healthy tissues. Consequently, researchers have created biomimetic nanoparticles covered with cell membranes using functional, targeted, and biocompatible coating technology. Nanoparticles with membranes can target specific cells, stay in circulation for longer, and avoid immune responses, which makes them much better at capturing CTCs. This study examines the current opportunities and difficulties associated with using cell membrane-coated nanoparticles as a capture technique for CTCs. In addition, we examine potential future developments in light of the current obstacles and investigate areas that require further research to fully understand its growing clinical possibilities.

Microfluidic-SERS Technologies for CTC: A Perspective on Clinical Translation.

Enumeration and phenotypic profiling of circulating tumor cells (CTCs) provide critical information for clinical diagnosis and treatment monitoring in cancer. To achieve this goal, an integrated system is needed to efficiently isolate CTCs from patient samples and sensitively evaluate their phenotypes. Such integration would comprise a high-throughput single-cell processing unit for the isolation and manipulation of CTCs and a sensitive and multiplexed quantitation unit to detect clinically relevant signals from these cells. Surface-enhanced Raman scattering (SERS) has been used as an analytical method for molecular profiling and in vitro cancer diagnosis. More recently, its multiplexing capability and power to create distinct molecular signatures against their targets have garnered attention. Here, we share our insights into the combined power of microfluidics and SERS in realizing CTC isolation, enumeration, and detection from a clinical translation perspective. We highlight the key operational factors in CTC microfluidic processing and SERS detection from patient samples. We further discuss microfluidic-SERS integration and its clinical utility as a paradigm shift in clinical CTC-based cancer diagnosis and prognostication. Finally, we summarize the challenges and attempt to look forward to what lies ahead of us in potentially translating the technique into real clinical applications.

Detecting androgen receptor (AR), AR variant 7 (AR-V7), prostate-specific membrane antigen (PSMA), and prostate-specific antigen (PSA) gene expression in CTCs and plasma exosome-derived cfRNA in patients with metastatic castration-resistant prostate cancer (mCRPC) by integrating the VTX-1 CTC isolation system with the QIAGEN AdnaTest

BackgroundTherapies for metastatic castration-resistant prostate cancer (mCRPC) include targeting the androgen receptor (AR) with androgen receptor inhibitors (ARIs) and prostate-specific membrane antigen (PSMA). Having the ability to detect AR, AR splice variant 7 (AR-V7), or PSMA in circulating tumor cells (CTCs) or circulating exosomal cell-free RNA (cfRNA) could be helpful to guide selection of the appropriate therapy for each individual patient. The Vortex Biosciences VTX-1 system is a label-free CTC isolation system that enables the detection of the expression of multiple genes in both CTCs and exosomal cfRNA from the same blood sample in patients with mCRPC. Detection of both AR-V7 and PSMA gene expression in both CTCs and cfRNA simultaneously has not yet been reported.MethodsTo characterize the combined VTX-1-AdnaDetect workflow, 22Rv1 cancer cells were spiked into blood from healthy donors and processed with the VTX-1 to mimic patient samples and assess performances (capture efficiency, purity, AR and AR-V7 expression). Then, we collected 19 blood samples from 16 patients with mCRPC and therapeutic resistance to androgen receptor inhibitors (ARIs). Plasma was separated and the plasma-depleted blood was processed further with the VTX-1 to collect CTCs. Both plasma exosomal cfRNA and CTCs were subsequently analyzed for AR, AR-V7, PSMA, and prostate-specific antigen (PSA) mRNA expression using the AdnaTest ProstateCancerPanel AR-V7 assay.ResultsAR-V7 expression could be detected in 22Rv1 cells spiked into blood from healthy volunteers as well as in CTCs and plasma-derived exosomal cfRNA from patients with mCRPC by processing blood with the VTX-1 CTC isolation system followed by the AdnaTest ProstateCancerPanel AR-V7 assay. 94.7% of patient blood samples (18/19) had detectable AR expression in either CTCs or exosomal cfRNA (16 in CTCs, 12 in cfRNA). 15.8% of the 19 patient blood samples (3/19) were found to have AR-V7-positive (AR-V7+) CTCs, one of which was also AR-V7+ in the exosomal cfRNA analysis. 42.1% of patient blood samples (8/19) were found to be PSMA positive (PSMA+): 26.3% (5/19) were PSMA+ in the CTC analysis and 31.6% (6/19) were PSMA+ in the exosomal cfRNA analysis. Of those 8 PSMA+ samples, 2 had detectable PSMA only in CTCs, and 3 had detectable PSMA only in exosomal cfRNA.ConclusionVTX-1 enables isolation of CTCs and plasma exosomes from a single blood draw and can be used for detecting AR-V7 and PSMA mRNA in both CTCs and cfRNA in patients with mCRPC and resistance to ARIs. This technology facilitates combining RNA measurements in CTCs and exosomal cfRNA for future studies to develop potentially clinically relevant cancer biomarker detection in blood.

Trajectory analysis of circulating tumor cells through contorted deterministic lateral displacement array for unruptured trapping: a simulation study

During the multistage process of cancer spread, fragments of cells branch out from the primitive tumor tissue and scatter throughout the body by blood flow stream or lymph, which are termed as circulating tumor cells (CTCs), regarded as an important biomarker for early cancer diagnosis. Deterministic lateral displacement (DLD) is one of the most efficient passive type particle isolation techniques which functions on asymmetrical laminar flow diversion around the placed microposts forming an array, based on the critical dimeter of the device. In this simulation study, complete trajectory analysis of CTCs and WBCs has been performed using COMSOL Multiphysics software with respect to the angular orientation of sample inlet channel. A simulated model of an asymmetric DLD array-based microfluidic device with latest empirical expression for critical diameter has been presented with optimized sample inlet orientation so as to maintain perfect separation efficiency of CTCs along with arrangement for unruptured trapping of CTCs and WBCs. The approximate CTC isolation efficiency was obtained above 95% for sample inlet inclinations up to 0.5°, and further tilt showed reduction in efficiency. Migration angle of CTC trajectory for the modeled device was obtained around 15° for both the sample inlet orientations leading to least intermingling of CTCs and WBCs. A smaller number of CTC–WBC interaction points was observed for clockwise sample inlet tilt compared to the anticlockwise displacement reducing possibilities of cell rupture. The shear rate around central microposts was found to be higher as well in clockwise sample inlet orientation. This simulation study establishes that sample inlet clockwise tilting of maximum around 0.5°–0.7° leads to better CTC isolation and provides better chances of unruptured trapping of cells at the designated outlets. The results of this study provide an approach toward further optimization of DLD devices' functioning and, thus, could help fabricate better DLD-based microfluidic devices for efficient trapping of CTCs.