Identification Of Circulating Tumor Cells Research Articles

Abstract 5368: A multiparameter assay for HER2 protein detection on circulating tumor cells in non-small cell lung cancer

Abstract Lung cancer biopsy can be difficult to perform successfully; it has a 30% adverse event risk and often provides insufficient material to test. Therefore, a liquid biopsy method to analyze the tumor is advantageous. Analysis of circulating tumor cells (CTCs) by multiparameter immunofluorescence (IF) microscopy allows non-invasive characterization of cancer cell biomarker expression. HER2 is a well-known therapeutic target in breast cancer and studies have shown that HER2 status on CTCs may provide prognostic information about response to anti-HER2 therapies. Less is understood about its frequency and clinical importance in non-small cell lung cancer (NSCLC). The RareCyte platform is uniquely suited for CTC identification and phenotypic characterization with a sensitive, accurate, simple and repeatable workflow from blood collection to CTC characterization and single-cell isolation. We developed an assay for detecting HER2 expression on lung CTCs using the RareCyte platform and validated the assay on model CTC spike-in samples with high (BT-474), medium (MDA-MB-453), low (H1650 and OVCAR-3) and absent (MDA-MB-468) HER2 protein levels. Blood was processed to slides using the AccuCyte Sample Preparation System and stained with anti-HER2 together with the RarePlex Kit for CTC identification (nuclear dye, anti-CD45 to exclude WBC, and anti-cytokeratin/EpCAM for CTCs). The spike-in samples showed the expected trend in per-cell HER2 mean fluorescence intensity values. The percentage of HER2-positive cells was > 90% for the HER2-high, medium and low cell lines, and < 5% for the HER2-negative cell line. The assay was applied to 10 advanced stage (III or IV) post-treatment NSCLC patient samples. At least 1 CTC was found in 6 samples (range 0-2043) and HER2 expression was confirmed in 5 out of the 6 samples, indicating this assay is useful for characterizing HER2 expression in CTCs in NSCLC. Citation Format: Edward Lo, Daniel Campton, Lillian Costandy, Heather Itamoto, Ryan Huston, Braden Gardner, Steve Reese, Arturo Ramirez, Eric P. Kaldjian, Tad George, I-Ming Wang, Steven Pirie-Shepherd. A multiparameter assay for HER2 protein detection on circulating tumor cells in non-small cell lung cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5368.

Abstract 5380: An integrated platform for the clinical detection and molecular profiling of single circulating tumor cells

Abstract Introduction: Detection of circulating tumor cells (CTCs) and characterization of CTCs at single-cell resolution may benefit the clinical management of cancer patients. To make the CTC analysis a “bench-to-bedside” technology, we developed an integrated platform named ChimeraX®-i120 system for the high-throughput, automated, and clinical applicable CTC sorting and downstream single-cell genomic profiling. Methods: ChimeraX®-i120 system is designed based on negative enrichment strategy, integrating blood sample pre-processing, immunofluorescence staining, artificial intelligence (AI)-assisted CTC identification. CTCs enriched by this system is compatible with downstream single-cell whole genome sequencing (WGS) analysis. Performance of CTCs detection was evaluated by a series of analytical experiments, clinical utility was further verified. We validated our downstream molecular profiling pipeline of single CTC. Results: Analytical experiments showed that this system was featured with high accuracy, repeatability, sensitivity and anti-interference capability for CTC detection, achieving an average recovery rate of the spiked cells in 71.3%-83.2% (R2= 0.99). In clinical samples, this system effectively detected CTCs and CTC clusters (CTM) in 5 mL blood from cancer patients. The proportion of patients that were positive for CTCs (EpCAM+/pan-CK++CD45-+DAPI+), was 59.3% (86/145, avg. cell count 1.38 ± 2.01) for hepatocellular carcinoma (HCC), 63.2% (24/38, 1.42 ± 1.75) for intrahepatic cholangiocarcinoma (ICC), 63.6% (28/44, avg. 2.52 ± 3.93) for breast cancer (BRC), 61.5% (24/39, avg. 1.62 ± 2.11) in colorectal cancer (CRC), 78.9% (15/19, avg. 2.74 ± 4.46) in lung cancer (LC). Only 1 of 125 (0.8%) healthy volunteers had detectable CTC. The prognostic value of the system was assessed in HCC. Preoperative CTC ≥1/5mL blood was significantly associated with a higher 1-year recurrence rate (38.9% vs. 27.6%, P=0.042) in HCC patients after curative surgery. Low-pass WGS analysis was performed on CTCs and paired tumor tissues of 3 ICC, 3 HCC and 4 BRC. We observed concordance in CNAs (10%-61%) between CTCs and tissues. CTC profiling identified diverse intra- and inter-patient heterogeneity in CNAs pattern. Exclusive CNA patterns were identified in CTCs but not tissue, and vice versa. Multiple well-known oncogenes (e.g., BRAF, EGFR, BRCA1/2, MYC and MET) and tumor suppressor genes (e.g., FOXA1 and TRAF3) could be identified from CNAs in CTCs. For example, in one BRC patient, potentially actionable alterations of BRC such as BRAF, EGFR, MET, ERBB2, PIK3CA and MYC were only identified in CTCs but not tissues. Conclusion: Our results highlight the potential clinical utility of ChimeraX®-i120 system in both CTC detection and downstream genomic profiling. Genomic sequencing of CTCs allows blood-based tumor profiling in greater fraction of patients for clinical decision making. Citation Format: Pengxiang Wang, Yunfan Sun, Weixiang Jin, Haixiang Peng, Jian Zhou, Jia Fan, Xinrong Yang. An integrated platform for the clinical detection and molecular profiling of single circulating tumor cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5380.

Dopamine-functionalized hyaluronic acid microspheres for effective capture of CD44-overexpressing circulating tumor cells

As one of the biomarkers of liquid biopsy, circulating tumor cells (CTCs) provides important clinical information for cancer diagnosis. However, accurate separation and identification of CTCs remains a great deal of challenge. In present work, we developed novel dopamine-functionalized hyaluronic acid microspheres (HA-DA microspheres) to capture CD44-overexpressing CTCs. The dopamine was grafted onto the hyaluronic acid chain, which was polymerized and cross-linked by oxidation of the catechol groups. Afterwards, a facile microfluidic chip was designed and developed to fabricate the HA-DA microspheres with a diameter of about 45 μm. Our results showed that the CD44+ cells (i.e., HeLa, HepG2, A549, MCF-7 and DU-145 cells) could be selectively captured. Then a double-layer microfluidic filter (DLMF) was fabricated for dynamic isolation and detection of CTCs in blood samples. Many slit openings with 15 μm in height were designed to allow white blood cells to clear away, while the microspheres with CTCs were intercepted in the DLMF, which achieved effective separation of CTCs from blood cells. The approach exhibited high capture efficiency even at the cell density as low as 10 cells/mL. We believe the DLMF integrated with HA-DA microspheres could be a promising approach for isolation and detection of CD44-overexpressing CTCs, which is useful for prognosis and early metastasis of cancer patients.

Label-free detection of rare circulating tumor cells by image analysis and machine learning

Detection and characterization of rare circulating tumor cells (CTCs) in patients' blood is important for the diagnosis and monitoring of cancer. The traditional way of counting CTCs via fluorescent images requires a series of tedious experimental procedures and often impacts the viability of cells. Here we present a method for label-free detection of CTCs from patient blood samples, by taking advantage of data analysis of bright field microscopy images. The approach uses the convolutional neural network, a powerful image classification and machine learning algorithm to perform label-free classification of cells detected in microscopic images of patient blood samples containing white blood cells and CTCs. It requires minimal data pre-processing and has an easy experimental setup. Through our experiments, we show that our method can achieve high accuracy on the identification of rare CTCs without the need for advanced devices or expert users, thus providing a faster and simpler way for counting and identifying CTCs. With more data becoming available in the future, the machine learning model can be further improved and can serve as an accurate and easy-to-use tool for CTC analysis.

A Pilot Study of the Predictive Potential of Chemosensitivity and Gene Expression Assays Using Circulating Tumour Cells from Patients with Recurrent Ovarian Cancer.

Circulating tumour cells (CTCs) from liquid biopsies are under current investigation in several cancers, including epithelial ovarian cancer (EOC) but face significant drawbacks in terms of non-standardised methodology, low viable cell numbers and accuracy of CTC identification. In this pilot study, we report that chemosensitivity assays using liquid biopsy-derived metastatic EOC CTCs, from 10 patients, nine with stage IIIC and one with stage IV disease, in progression after systemic chemotherapy, submitted for hypoxic isolated abdominal perfusion (HAP), are both feasible and useful in predicting response to therapy. Viable metastatic EOC CTCs (>5 cells/mL for all 10 blood samples), enriched by transient culture and identified by reverse transcription polymerase chain reaction (RT-PCR) and indirect immunofluorescence (IF), were subjected to flow cytometry-based Annexin V-PE assays for chemosensitivity to several chemotherapeutic agents and by RT-PCR for tumour gene expression profiling. Using a cut-off value of >80% cell death, CTC chemosensitivity tests were predictive of patient RECIST 1.1 responses to HAP therapy associated with 100% sensitivity, 50% specificity, 33% positive predictive, 100% negative predictive and 60% accuracy values. We propose that the methodology employed in this study is feasible and has the potential to predict response to therapy, setting the stage for a larger study.

ISSUE HIGHLIGHTS - July 2020.

ISSUE HIGHLIGHTS - July 2020.

Abstract PR10: Analytical validation and preliminary clinical utility of PD-L1 and HLA I expression profiling of circulating tumor cells using automated exclusion-based sample preparation technology

Abstract Only a subset of patients with non-small cell lung cancer (NSCLC) respond to PD-L1 targeted therapy, even after solid tumor biopsy screening for PD-L1 expression. Downregulation of HLA I may contribute to this high prevalence of resistance, warranting its inclusion in attempts to increase response rates. While it is unclear if loss of HLA I occurs as a de novo or acquired resistance mechanism to immunotherapy, liquid biopsies could detect dynamic changes in expression levels, enable early detection of resistance, and accelerate the shift to alternate, more effective treatments. To quantify the expression of both PD-L1 and HLA I on circulating tumor cells (CTCs), we have developed automated exclusion-based sample preparation technology (ESP), which leverages the forces of surface tension and magnetism at the microscale for high-efficiency, high-throughput cell capture and manipulation. On-chip fluorescent antibody staining is performed for CTC identification, enumeration, and analysis of protein expression. A quantitative readout of protein expression is performed using a refined fluorescence microscopy approach wherein images of cells are acquired and analyzed with automated algorithms for uniformity and objectivity. To evaluate precision, accuracy, and analytical sensitivity of both ESP processing and quantitative microscopy, we used standardized cell lines, synthetic beads, and patient sample replicates. Calibration beads demonstrate high precision between multiple users for the quantitative microscopy (0.9% CV max of all wavelengths between 3 different analysts). ELISA beads with serial dilutions of protein standards demonstrate the accuracy of the quantitative microscopy (R2 values of 0.99 for both proteins). Cell lines demonstrate the precision of ESP for protein staining (3.4% CV max of two different cell lines tested on three different days). Patient sample replicates demonstrate precision for patients with as few as 3 CTCs per sample (6% CV max between triplicates). Early clinical utility of this assay was demonstrated on a preliminary patient cohort of 21 patient time points from 8 unique patients with NSCLC treated with immunotherapies. Phenotypic analysis for CTC expression of PD-L1 and HLA I with this assay demonstrated a sensitivity of 94% and specificity of 75% for detecting either resistant or stable disease during treatment with immunotherapies. Preliminary evaluation of patients with clear cell renal cell carcinoma demonstrates the feasibility of applying this approach to other cancer types. By confirming high performance, we ensure compatibility for clinical laboratory implementation and eventual application to better predict and detect resistance to PD-L1 targeted therapy in patients with NSCLC. The preliminary patient cohort suggests this diagnostic approach can detect fluctuations in expression of PD-L1 and HLA I in CTCs that also correspond to patient response to immunotherapy and warrants its pursuance in larger cohorts of patients with NSCLC and other tumor types. This abstract is also being presented as Poster B38. Citation Format: Jennifer L. Schehr, Zachery D. Schultz, Camila I. Hernandez, Matthew C. Mannino, Jay W. Warrick, Ticiana A. Leal, David J. Beebe, Joshua M. Lang. Analytical validation and preliminary clinical utility of PD-L1 and HLA I expression profiling of circulating tumor cells using automated exclusion-based sample preparation technology [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr PR10.

Detection of Circulating Tumor Cells by Fluorescence Microspheres-Mediated Amplification.

Here we describe a fluorescent microspheres-based separation and analysis that enables the isolation of circulating tumor cells (CTCs) from whole blood of patients with metastatic cancer and the identification of isolated CTCs in situ without immunostaining. This approach uses antibody-functionalized fluorescent polystyrene (PS) microspheres that can selectively bind to CTCs. The binding of CTCs and fluorescent PS microspheres leads to the formation of complexes of CTCs and fluorescent PS microspheres, thereby the CTCs are size-amplified and labeled simultaneously. A pyramidal microcavity array (PMCA) is fabricated using microfabrication technology to create a precise microfilter structure with a high aspect ratio. The PMCA filter device can effectively isolate microspheres-labeled CTCs, while allow hematologic cells to deform and pass through. Using this approach, CTCs are isolated and identified in 15 of 18 patients with metastatic colorectal cancer. This approach will open new possibilities for CTCs isolation and identification and can serve a versatile platform to facilitate CTCs analysis in diverse biomedical applications.

Circulating tumor cells in breast cancer.

Breast cancer is the most recurrent cancer in female population, its mortality is related to the presence of distant metastases. Distant metastasis begins as a small group of cells that spread regionally and remotely from the site of primary origin. Circulating tumor cells (CTC) are present in the blood of cancer patients and are therefore considered disease markers and precursors of metastasis. It is trascendental the review of the molecular aspects of the metastatic process, the available techniques for the enrichment, identification and molecular characterization of CTC, as well as some examples of its usefulness and clinical application in patients with breast cancer, including aspects related to perioperative management during breast cancer surgery.

Identification of circulating tumor cells using 4-color fluorescence in situ hybridization: Validation of a noninvasive aid for ruling out lung cancer in patients with low-dose computed tomography-detected lung nodules.

Approximately one third of needle biopsies that are performed to rule out malignancy of indeterminate pulmonary nodules detected radiologically during lung cancer screening are negative, thus exposing cancer-free patients to risks of pneumothorax, bleeding, and infection. A noninvasive confirmatory tool (eg, liquid biopsy) is urgently needed in the lung cancer diagnosis setting to stratify patients who should receive biopsy versus those who should be monitored. A novel antigen-independent, 4-color fluorescence in situ hybridization (FISH)-based method was developed to detect circulating tumor cells (CTCs) with abnormalities in gene copy numbers in mononuclear cell-enriched peripheral blood samples from patients with (n=107) and without (n=100) lung cancer. Identification of CTCs using FISH probes at 10q22.3/CEP10 and 3p22.1/3q29 detected lung cancer cases with 94.2% accuracy, 89% sensitivity, and 100% specificity compared with biopsy. The high accuracy of this liquid biopsy method suggests that it may be used as a noninvasive decision tool to reduce the frequency of unnecessary needle biopsy in patients with benign pulmonary lesions.

MP55-08 FEASIBILITY OF FINDING CIRCULATING TUMORS CELLS AND ASSIGNING PD-L1 RECEPTOR STATUS USING SINGLE-CELL TECHNOLOGY COMBINED WITH CELSEE GENESIS SYSTEM

INTRODUCTION AND OBJECTIVE: enumerating circulating tumor cells (CTC) may improve our ability to differentiate between localized and metastatic bladder cancer (BC) and predict response to systemic therapies. However, previously used CTC identification platforms had limited utility in managing patients diagnosed with this disease because they lacked the appropriate sensitivity level. Also, they did not report on the PD-L1 receptor status, which is becoming an essential component of modern immunotherapy of BC METHODS: We used a novel device to enrich and retrieve CTCs from blood samples of patients with high grade and low-grade BC, as well as benign conditions, treated with cystectomy by using a microfluidic chip. The Celsee Genesis (Celsee Inc) captures CTCs with high sensitivity and allows the captured CTCs to be retrieved for molecular analysis. It uses the microfluidic chip, which has approximately 56,320 capture chambers. Based on differences in cell size and deformability, each chamber ensures that small blood cells escape while larger CTCs of varying sizes are trapped and isolated in the chambers. PD-L1 expression on the isolated tumor cells was then evaluated using 4-color single-cell technology (IncellDX Inc.) directly on the chip. RESULTS: Ten bladder cancer (5 extensive low grade (LG) and 5 invasive high grade (HG) disease) and two benign bladder pathology patients provided blood samples before their cystectomy. We found CTCs in 3 patients (two LG and one HG disease). CTCs were four times higher in the HG sample than in the LG samples. PD-L1 expression was high on CTCs isolated from the HG patient’s blood sample and lower in the two LG blood samples. No CTCs were detected in patients with benign bladder pathology. CONCLUSIONS: Our results show the feasibility of using novel, high sensitivity CTC detection, and PD-L1 single cell measuring technology in patients with BC. We also show that this technology has a potentially high sensitivity level for detecting CTC in patients with bladder malignancies by detecting low levels of CTCs in low-grade disease. More extensive studies are planned to validate our findings.Source of Funding: IncellDX and CelSee Inc.

Evaluation of HER2 expression in urothelial carcinoma cells as a biomarker for circulating tumor cells.

Detection of circulating tumor cells (CTC) by techniques based on epithelial cell adhesion molecule (EpCAM) is suboptimal in urothelial carcinoma (UC). As HER2 is thought to be broadly expressed in UC, we explored its utility for CTC detection. HER2 and EpCAM expression was analyzed in 18 UC cell lines (UCCs) by qRT-PCR, western blot and fluorescence-activated cell scanning (FACS) and compared to the strongly HER2-expressing breast cancer cell line SKBR3 and other controls. HER2 expression in UC patient tissues was measured by qRT PCR and correlated with data on survival and risk for metastasis. UCCs with high EpCAM and variable HER2 expression were used for spike-in experiments in the CellSearch system. Twenty-one blood samples from 13 metastatic UC patients were analyzed for HER2-positive CTCs with CellSearch. HER2 mRNA and protein were broadly expressed in UCC, with some heterogeneity, but at least 10-fold lower than in the HER-2+ SKBR3 cells. Variations were unrelated to cellular phenotype or clinicopathological characteristics. EpCAM expression was essentially restricted to UCCs with epitheloid phenotypes. Heterogeneity of EpCAM and HER2 expression was observed also in spike-in experiments. The 7 of 21 blood samples from 6 of 13 patients were enumerated as CTC positive via EpCAM, but only one sample stained weakly positive (1+) for HER2. Detection rate of CTCs by EpCAM in UC is poor, even in metastatic patients. Because of its widespread expression, particularly in patients with high risk of metastasis, detection of HER2 could improve identification of UC CTCs, which is why combined detection using antibodies for EpCAM and HER2 may be beneficial.

Circulating Tumor Cells as a Tool of Minimal Residual Disease Can Predict Lung Cancer Recurrence: A longitudinal, Prospective Trial.

Background: The role of circulating tumor cells (CTCs) for predicting the recurrence of cancer in lung cancer patients after surgery remains unclear. Methods: A negatively selected protocol of CTC identification was applied. For all the enrolled patients, CTC testing was performed before and after surgery on the operation day (day 0), postoperative day 1, and day 3. The daily decline and trend of CTCs were analyzed to correlate with cancer relapse. The mixed model repeated measures (MMRM) adjusted by cancer characteristics was applied for statistical significance. Results: Fifty patients with lung mass undergoing surgery were enrolled. Among 41 primary lung cancers, 26 (63.4%) were pathological stage Tis and I. A total of 200 CTC tests were performed. MMRM analysis indicated that surgery could contribute to a CTC decline after surgery in all patients with statistical significance (p = 0.0005). The daily decrease of CTCs was statistically different between patients with and without recurrence (p = 0.0068). An early rebound of CTC counts on postoperative days 1 and 3 was associated with recurrence months later. Conclusion: CTC testing can potentially serve as a tool for minimal residual disease detection in early-staged lung cancer after curative surgery.

Heterogeneity of Circulating Tumor Cells in Breast Cancer: Identifying Metastatic Seeds.

Metastasis being the main cause of breast cancer (BC) mortality represents the complex and multistage process. The entrance of tumor cells into the blood vessels and the appearance of circulating tumor cells (CTCs) seeding and colonizing distant tissues and organs are one of the key stages in the metastatic cascade. Like the primary tumor, CTCs are extremely heterogeneous and presented by clusters and individual cells which consist of phenotypically and genetically distinct subpopulations. However, among this diversity, only a small number of CTCs is able to survive in the bloodstream and to form metastases. The identification of the metastasis-initiating CTCs is believed to be a critical issue in developing therapeutic strategies against metastatic disease. In this review, we summarize the available literature addressing morphological, phenotypic and genetic heterogeneity of CTCs and the molecular makeup of specific subpopulations associated with BC metastasis. Special attention is paid to the need for in vitro and in vivo studies to confirm the tumorigenic and metastatic potential of metastasis-associating CTCs. Finally, we consider treatment approaches that could be effective to eradicate metastatic CTCs and to prevent metastasis.

Chemokine signaling and MAPK/ERK pathway for advanced prostate cancer treatment response.

TPS275 Background: Androgen deprivation therapy (ADT) is the backbone of therapy for metastatic hormone sensitive prostate cancer (mHSPC). Despite a high response rate, the majority of patients progress to metastatic castration-resistant prostate cancer (mCRPC). Both disease settings are heterogeneous with variable responses to treatment. While prostate specific antigen is an important biomarker for prognosis and disease monitoring, it has limitations. Biomarkers predictive of disease response and progression are critically needed. Circulating tumor cells (CTCs) are shed from tumors and are found in blood during advanced stages of disease. Serial characterization of CTCs serves as a real-time ‘liquid biopsy’ for molecular profiling of PC. Recent reports suggest that phenotypic & genomic heterogeneity in CTCs and cell-free DNA (cfDNA) is associated with response to AR-targeted therapy highlighting the importance of CTC as a predictive biomarker. In addition, there is a high concordance between mutations in CTCs’ DNA and CRPC tissue through whole cell exome sequencing. We showed that atypical chemokine receptor CXCR7 is up-regulated following AR-targeted therapies, activating MAPK/ERK signaling and resulting in treatment resistance (Li et al., Cancer Res. 2019). To examine the potential of CXCR7/MAPK/ERK signaling in predicting treatment response, we propose to evaluate MAPK/ERK gene signature, pERK and AR level in CRPC or mHSPC patients receiving systemic therapy. Methods: Men with new CRPC or mHSPC are eligible prior to initiating new therapy for the respective disease setting of ADT + AR targeted therapy or chemotherapy. For CRPC arm, we will collect samples at baseline, 3, 6 months & at time of progression. For mHSPC arm, samples are collected at baseline, after 7 months & at progression. We will enroll 120 patients. Collected samples are subjected to identification, isolation, and enumeration of CTCs. Our primary molecular testing will include AR and pERK staining. CfDNA exome and methylome analysis will be performed to evaluate genomic heterogeneity and epigenomic alterations. We will explore pairwise association among biomarkers of interest, stratified by subgroups, using measures of association.

Feasibility of finding circulating tumors cells and assigning PD-L1 receptor status using single-cell technology combined with Celsee Genesis system.

567 Background: enumerating circulating tumor cells (CTC) may improve our ability to differentiate between localized and metastatic bladder cancer (BC) and predict response to systemic therapies. However, previously used CTC identification platforms had limited utility in managing patients diagnosed with this disease because they lacked the appropriate sensitivity level. Also, they did not report on the PD-L1 receptor status, which is becoming an essential component of modern immunotherapy of BC. Methods: We used a novel device to enrich and retrieve CTCs from blood samples of patients with high grade and low-grade BC, as well as benign conditions, treated with cystectomy by using a microfluidic chip. The Celsee Genesis (Celsee Inc) captures CTCs with high sensitivity and allows the captured CTCs to be retrieved for molecular analysis. It uses the microfluidic chip, which has approximately 56,320 capture chambers. Based on differences in cell size and deformability, each chamber ensures that small blood cells escape while larger CTCs of varying sizes are trapped and isolated in the chambers. PD-L1 expression on the isolated tumor cells was then evaluated using 4-color single-cell technology (IncellDX Inc.) directly on the chip. Results: Ten bladder cancer (5 low grade (LG) and 5 high grade (HG) disease) and two benign bladder pathology patients provided blood samples before their cystectomy. Circulating tumor cells were found in 3 patients (two LG and one HG disease). CTCs were four times higher in the HG sample than in the LG samples. PD-L1 expression was high on CTCs isolated from the HG patient’s blood sample and lower in the two LG blood samples. No CTCs were detected in patients with benign bladder pathology. Conclusions: Our results show the feasibility of using novel, high sensitivity CTC detection and PD-L1 single cell measuring technology in patients with BC. We also show that this technology has a potentially high sensitivity level for detecting CTC in patients with bladder malignancies by detecting low levels of CTCs in low-grade disease. More extensive studies are planned to validate our findings.

Electrostatic reaction for the detection of circulating tumor cells as a potential diagnostic biomarker for metastasis in solid tumor.

The detection of circulating tumor cells (CTCs) from blood samples is important to predict metastatic spread of cancer cells. However, effective quantification and identification of CTCs in solid tumors remain a challenge. Aerobic glycolysis is a hallmark of cancer cells, which makes cancer cells have more negative membrane potentials than that of normal cells. Herein, we reported a CTC isolation method with 80.7% capture efficiency based on electrostatic reaction, which was accomplished within 30 min in mimic clinical samples. Following in vitro verification using Lewis lung carcinoma (LLC1) (EpCAM-positive) and B16F10 (EpCAM-negative) melanoma cells, syngeneic tumor models were used to evaluate specificity and sensitivity of the surface charged nanoparticles. After subcutaneous implantation, blood was drawn from mice every three days, and CTCs were successfully detected in all implanted subjects. From 100 µl blood samples, the minimum amount found in blood was 9-34 CTCs on 3 day and the maximum was 94-107 CTCs on 15 day. Besides, the isolated CTCs cells remained viable and verified by re-implantation. This study confirms that our multifunctional nanoparticles are highly efficient in detecting CTCs in tumor metastasis and has huge potential in translational medicine.

Liquid Biopsy: Detection of Circulating Tumor Cells in Esophageal Squamous Cell Carcinoma.

Circulating tumor cells (CTC) harvested in the blood of patients with esophageal squamous cell carcinoma (ESCC) are associated with certain clinical pathological parameters as well as patients' prognosis and response to chemoradiation. They are the source of distant metastases and their mechanisms of pathogenesis is complex. In recent years, advance in technologies has allowed scientists to detect, enumerate, and isolate these cells for further analysis and monitor the diseases progression in patients with cancer. There are a few methods available for the identification of individual CTC and clusters of CTCs (circulating tumor microemboli). The most commonly used is detection by immunomagnetic method. Although all these methods have limitations, they are helpful for understanding the pathogenesis of CTCs with potential applications in clinical managements in patients with ESCC.

Circulating tumor cells detection in tumor draining vein of breast cancer patients

Circulating tumor cells (CTCs) in tumor draining vein blood (DB) are potential sources for liquid biopsy. However, the identification of CTCs in DB of breast cancer has not been attempted. In this study, we investigated the feasibility of CTC detection in DB of breast cancer patients using a newly developed filtration-based microfluidic CTC detection device. Samples of peripheral vein blood (PB) and DB drawn from the lateral thoracic vein of the resected breast tissue were collected during the perioperative period. We investigated 41 breast cancer patients who underwent breast surgery with axillary lymph node dissection. DB was successfully collected in 36 patients (87.8%), with a mean amount of 0.85 ml. CTCs were detected in 58.3% of PB samples and 80.6% of DB samples. DB had significant higher number of CTCs compared with PB (p < 0.001). CTCs were detected in 75.0% of DB samples and 50.0% of PB samples from patients achieving pathological complete response after neoadjuvant chemotherapy. These results suggest that abundant CTCs are released into the DB of breast cancer patients, indicating that CTCs in DB would be alternative sources for liquid biopsy and potential indicators for monitoring of treatment response and prognosis in breast cancer patients.

Abstract A032: Clinical significance of vimentin-positive AXL-expressing circulating tumor cells in advanced non-small-cell lung cancer patients

Abstract Purpose: Circulating tumor cells (CTCs) have a potential for the noninvasive decision-making. AXL, a receptor tyrosine kinase is associated with promoting cell proliferation, migration, epithelial-to-mesenchymal transition and drug resistance. We previously reported that the establishment of the detection method of AXL-expressing CTCs by an automated microcavity array (MCA) system incorporating mesenchymal marker vimentin (VM). Here we analyzed the clinicopathological correlation with VM-positive AXL-expressing CTCs in advanced non-small-cell lung cancer (NSCLC) patients. Methods: For detecting CTCs, 6 mL of peripheral blood collected from patients was divided into two portions and used for CTC identification in parallel incorporating markers cytokeratin (CK) and VM, respectively. An automated MCA system was used for enrichment and staining for CD45, DAPI, CK or VM with the additional staining for AXL. DAPI-positive, CK or VM-positive, and CD45-negative cells were defined as CTCs. All statistical analyses were carried out using GraphPad Prism 6 and Mann-Whitney U test, Fisher’s exact test, and rog-rank test were performed accordingly. A p value &amp;lt;0.05 was considered as significant. Results: Twenty advanced NSCLC were enrolled in this clinical study between May and October 2018 at Wakayama Medical University Hospital. Clinical data was tracked until May 2019. The patient characteristics were as follows: median age 70 years (range, 54-82); male 80%; stage III/IV, 10/90%; adenocarcinoma/ squamous cell carcinoma/ other, 65/30/5%. VM-positive single CTCs were detected in 95% of patients (median, 3; range, 0-54) and AXL-expressing VM-positive single CTCs were detected in 60% of patients (median, 1; range, 0-42). AXL-positivity rates in single VM-positive CTCs between patients with previous treatment and those without were compared and patients with previous treatment harbored significantly higher AXL-positivity (p &amp;lt; 0.05). We also assessed the impact of AXL-expressing CTCs on the following treatment in 16 patients from whom we obtained the response data. Cutoff value for segregating partial response + stable disease (n = 13) from progressive disease (n = 3) to the following treatment was 45% of AXL-positivity on VM-positive single CTCs according to receiver operating characteristic curve and p value was 0.071, suggesting the trend favoring AXL-positive CTCs for predicting progressive disease. Progression free survival of treatment following CTC detection was significantly shorter in patients with 45% or more AXL positivity in CTCs (n = 3; median, 41 days) than in those with less than 45% of them (n = 13; median, not reached) (p &amp;lt; 0.01). Conclusion: Our data indicate that detection of AXL-expressing CTCs may have a potential to be indicative of poor prognosis and acquired drug resistance. Citation Format: Mio Ikeda, Yasuhiro Koh, Shunsuke Teraoka, Koichi Sato, Kuninobu Kanai, Atsushi Hayata, Nahomi Tokudome, Hiroaki Akamatsu, Yuichi Ozawa, Keiichiro Akamatsu, Katsuya Endo, Masayuki Higuchi, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Clinical significance of vimentin-positive AXL-expressing circulating tumor cells in advanced non-small-cell lung cancer patients [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A032. doi:10.1158/1535-7163.TARG-19-A032