Viable Circulating Tumor Cells Research Articles

Deep Learning-Assisted Assessing of Single Circulating Tumor Cell Viability via Cellular Morphology.

Circulating tumor cells (CTCs) are closely associated with cancer metastasis and recurrence, so the assessment of CTC viability is crucial for diagnosis, prognosis evaluation, and efficacy judgment of cancer. Due to the extreme scarcity of CTCs in human blood, it is difficult to accurately evaluate the viability of a single CTC. In this study, a deep learning model based on a convolutional neural network was constructed and trained to extract the morphological features of CTCs with different viabilities defined by cell counting kit-8, achieve accurate CTC identification, and assess the viability of a single CTC. Being efficient, accurate, and noninvasive, it has a broad application prospect in biomedical directions.

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.

Abstract 199: Fluid shear stress enhances metastatic potential and rapidly alters metabolism of circulating tumor cells

Abstract Background and Purpose: Circulating tumor cells (CTCs) are exposed to mechanical and biochemical stresses including fluid shear stress (FSS) and oxidative distress. Recently we have shown that viable CTCs actively resist destruction when exposed to FSS by a mechano-adaptive mechanism that depends on RhoA-actomyosin activity [PMID: 32187555]. Since the RhoA-actomyosin axis is implicated in other cellular behaviors that might contribute to metastasis; herein, we explored the hypothesis that exposure to FSS alters the biology of viable CTCs to promote metastatic colonization. Methodology: To determine if exposure to FSS alters metastatic potential, we exposed PC-3 prostate and MDA-MB-231 breast cancer cells to FSS prior to injection into the tail-vein of NCG mice. We then monitored metastatic colonization by weekly bioluminescence imaging. Further, we examined if FSS exposure altered the invasive potential of PC-3 and MDA-MB-231 cells, as well as their ability to survive/proliferate under anchorage-independent conditions. We conducted GC/LC-MS metabolomic profiling and measured lactate production following FSS exposure. To investigate oxidative burden on FSS exposed cells, we used dihydroethidium to measure general ROS production and a lipid peroxide sensor. Results: We found that FSS exposure shortens the time for metastatic colonization for both cell lines. We found that FSS exposure leads to approximately two-fold increase in invasion through collagen matrix, which, for PC-3 cells, is RhoA dependent. Moreover, FSS exposure resulted in increased proliferation (~25%) under anchorage independent conditions in both cell lines. Metabolomic profiling revealed that FSS exposure resulted increased glycolysis, reduced entry into the TCA cycle, and increased lactate levels. We blocked glycolysis in PC-3 and MDA-MB-231 cells with 2-deoxyglucose and found that this increased the fraction of cells destroyed by FSS ~20-30%. We also investigated redox stress and found that compared to cells held in suspension, those exposed to FSS demonstrate lower ROS burden. Interestingly, cells exposed to FSS exhibit lower levels of lipid peroxides in a manner that depends on RhoA. Conclusion: Our findings demonstrate that brief pulses of FSS exposure can enhance metastatic potential, increase invasive and anchorage-independent proliferative capacity and rapidly alter metabolism. The phenotypic changes driven by exposure to FSS depend in part on RhoA activation but may also reflect other mechanisms by which cancer cells sense and respond to FSS. The rapid changes in metabolism may act to reduce oxidative distress while CTCs are in suspension. In summary, our data indicate that FSS exposure in the circulation not only represents a physical force that CTCs must overcome to survive, but it also provides instructive cues that may enhance the metastatic behavior of some CTCs. Citation Format: Devon L. Moose, Amanda N. Pope, Marion Dykstra, Eric B. Taylor, Patrick Breheny, Michael D. Henry. Fluid shear stress enhances metastatic potential and rapidly alters metabolism of circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 199.

Abstract 3691: Molecular profiling using next generation sequencing with high purity enrichment of circulating tumor cells

Abstract Purpose: In the area 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 shows that complementary sequential CTCs and ctDNA profiling provide promising benefit for prognosis and treatment. In contrast to well-established ctDNA extraction methods, the process of isolating intact CTCs for NGS analysis is yet to be fully elucidated. Here, we show that the isolation and harvest of viable CTCs by CytoGen’s Smart Biopsy™ System enable the attainment of sufficiently high purity for NGS analysis in metastatic breast cancer. 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) which were spiked into 5 mL healthy blood, to mimic CTC. The CytoGen’s Smart Biopsy™ system was applied to isolate the CTC. Then, CD45 depletion and whole genome amplification were performed. Sequencing was carried out on Ion S5™ XL systems using an Ion 550™ Chip Kit. Subsequently, sequencing data was analyzed using Ion Torrent software with default configurations. Results: As a result of targeted panel sequencing using Oncomine™ Comprehensive Assay Plus, representative mutated genes (BRAF, KRAS, TP53, NF2 and NOTCH3) in breast cancer 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 even with only 5 MDA-MB-231 cells. These results suggest that clinical sample of breast cancer could be applied with promising sensitivity and specificity for detection of representative mutated genes. Conclusion: 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. In this study, we developed the process for NGS analysis on very low number of CTCs with high purity, isolated using CytoGen's Smart Biopsy™ system. Overall, these process could provide information for diagnosis and appropriate treatment of metastatic breast cancer along with the results of our ongoing clinical trials. Citation Format: Sehwan Park, Jaesung Choi, Aejin Jeong, Hanbyeol Kim, Jiyoun Oh, Ingeon Jang, Hoin Kang, Jihyun Lee, Sehyung Pak, Min-Ji Song, Jung Won Kim, Hai-Chon Lee. Molecular profiling using next generation sequencing with high purity enrichment of circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3691.

Microfluidic System Consisting of a Magnetic 3D-Printed Microchannel Filter for Isolation and Enrichment of Circulating Tumor Cells Targeted by Anti-HER2/MOF@Ferrite Core-Shell Nanostructures: A Theranostic CTC Dialysis System.

Low number of circulating tumor cells (CTCs) in the blood samples and time-consuming properties of the current CTC isolation methods for processing a small volume of blood are the biggest obstacles to CTC usage in practice. Therefore, we aimed to design a CTC dialysis system with the ability to process cancer patients' whole blood within a reasonable time. Two strategies were employed for developing this dialysis setup, including (i) synthesizing novel in situ core-shell Cu ferrites consisting of the Cu-CuFe2O4 core and the MIL-88A shell, which are targeted by the anti-HER2 antibody for the efficient targeting and trapping of CTCs; and (ii) fabricating a microfluidic system containing a three-dimensional (3D)-printed microchannel filter composed of a polycaprolactone/Fe3O4 nanoparticle composite with pore diameter less than 200 μm on which a high-voltage magnetic field is focused to enrich and isolate the magnetic nanoparticle-targeted CTCs from a large volume of blood. The system was assessed in different aspects including capturing the efficacy of the magnetic nanoparticles, CTC enrichment and isolation from large volumes of human blood, side effects on blood cells, and the viability of CTCs after isolation for further analysis. Under the optimized conditions, the CTC dialysis system exhibited more than 80% efficacy in the isolation of CTCs from blood samples. The isolated CTCs were viable and were able to proliferate. Moreover, the CTC dialysis system was safe and did not cause side effects on normal blood cells. Taken together, the designed CTC dialysis system can process a high volume of blood for efficient dual diagnostic and therapeutic purposes.

Multi-DNA-Modified Double-Network Hydrogel with Customized Microstructure: A Novel System for Living Circulating Tumor Cells Capture and Real-Time Detection.

The precise and effective isolation of living circulating tumor cells (CTCs) from peripheral blood, followed by their real-time monitoring, is crucial for diagnosing cancer patients. In this study, a cell-imprinted double-network (DN) hydrogel modified with circular multi-DNA (CMD), coined the CMD-imprinted hydrogel with fixed cells as templates (CMD-CIDH), was developed. The hydrogel featured a customized surface for proficient capture of viable CTCs and in situ real-time fluorescent detection without subsequent release. The customized surface, constructed using polyacrylamide/chitosan DN hydrogel as the matrix on the cell template, had a dense network structure, thereby ensuring excellent stability and a low degradation rate. Optimal capture efficiencies, recorded at 93 ± 3% for MCF-7 cells and 90 ± 2% for Hela cells, were achieved by grafting the CMD and adjusting the nodule size on the customized surface. The capture efficiency remained significantly high at 67 ± 11% in simulated breast cancer patient experiments even at a minimal concentration of 5 cells mL-1. Furthermore, CMD grafted onto the surface produced a potent fluorescence signature, enabling in situ real-time fluorescent detection of the target cell's growth state even in complex environments. The customized surface is highly efficient for screening CTCs in peripheral blood and has promising potential for setting up the CTCs culture.

Functional Analysis of Viable Circulating Tumor Cells from Triple-Negative Breast Cancer Patients Using TetherChip Technology.

Metastasis, rather than the growth of the primary tumor, accounts for approximately 90% of breast cancer patient deaths. Microtentacles (McTNs) formation represents an important mechanism of metastasis. Triple-negative breast cancer (TNBC) is the most aggressive subtype with limited targeted therapies. The present study aimed to isolate viable circulating tumor cells (CTCs) and functionally analyze them in response to drug treatment. CTCs from 20 TNBC patients were isolated and maintained in culture for 5 days. Biomarker expression was identified by immunofluorescence staining and VyCap analysis. Vinorelbine-induced apoptosis was evaluated based on the detection of M30-positive cells. Our findings revealed that the CTC absolute number significantly increased using TetherChips analysis compared to the number of CTCs in patients' cytospins (p = 0.006) providing enough tumor cells for drug evaluation. Vinorelbine treatment (1 h) on live CTCs led to a significant induction of apoptosis (p = 0.010). It also caused a significant reduction in Detyrosinated α-tubulin (GLU), programmed death ligand (PD-L1)-expressing CTCs (p < 0.001), and disruption of McTNs. In conclusion, this pilot study offers a useful protocol using TetherChip technology for functional analysis and evaluation of drug efficacy in live CTCs, providing important information for targeting metastatic dissemination at a patient-individualized level.

BIOL-08. RADIATION DRIVES METASTASIS IN MEDULLOBLASTOMA THROUGH AN INFLAMMATORY PROCESS

Abstract Current treatment for medulloblastoma is comprised of surgery, radiotherapy (RT) and/or chemotherapy. Although the primary tumor is controlled with this approach, recurrent metastatic disease is ubiquitously fatal. However, little is known about the biology of metastatic recurrences in medulloblastoma. In the present study, we observe across 3 non-overlapping cohorts of infant medulloblastoma that patients recur locally without focal RT and metastatically after focal RT. Using 3 independent murine flank xenograft medulloblastoma models, we found that the incidence of leptomeningeal metastasis was significantly increased in mice that received RT compared to sham controls. We have also found a significant increase in viable circulating tumor cells after RT. Our multi-omics (bulk RNA-seq, scRNA-seq and proteo/phosphoproteomics) approach using immunocompetent sporadic medulloblastoma models treated with RT showed activation of the innate inflammatory response through the overexpression of chemokines, cytokines and activation of immune cell types. In situ analysis of protein expression after RT showed a gradual increase in the abundance of macrophages, neutrophils and dendritic cells after RT, suggesting increased permeability and cell trafficking across the blood brain barrier. Applying live intravital microscopy using a low molecular weight vascular dye (150kDa), we observed a striking increase in blood vessel permeability in RT vs sham-treated brain tumors. Our observations support a model where RT drives metastasis through inflammation. To test this, we applied lipopolysaccharide (LPS), an inflammation inducing treatment, to a sporadic murine medulloblastoma model which significantly increased the metastatic burden. We then treated a xenograft model with dexamethasone in combination with RT, which resulted in total abrogation of metastatic dissemination compared to RT alone. Collectively, our findings suggest that while external beam irradiation is an effective and essential treatment for medulloblastoma, it may facilitate metastatic dissemination through an inflammation-induced process. These findings can help inform potential approaches to prevent disseminated relapsed disease.

Treatment response prediction with circulating tumor cell-derived organoids for soft tissue sarcoma.

e23521 Background: Pharmacologic treatment for soft tissue sarcoma (STS) remains challenging. There is a lack to predict treatment responses to chemotherapy or targeted therapy to oncologic drivers. We hypothesize that circulating tumor cells may enrich cancer initiating cells and represent a window to probe personalized drug treatment response. In this study, we test if drug sensitivity profile of short-term culture of tumor organoids derived from circulating tumor cells (CTCs) correlates to clinical treatment response. Methods: From April 2019 to December 2020, 50 patients with biopsy-confirmed STS, who had either recurrent or metastatic tumors, were enrolled in a prospective observational study in Taipei Medical University Hospital. The median age of the patients was 47, and the top 3 diagnoses were leiomyosarcoma, aggressive fibromatosis and rhabdomyosarcoma. 74% of patients had metastatic diseases at the time of blood collection. Fifty-five blood samples were collected and processed for CTC organoid culture and drug sensitivity analysis (EVASelect, CancerFree Biotech, Taipei, Taiwan), which involves culturing nucleated blood cells on a binary colloid crystal-coated surface. Clinical response was evaluated using RECIST criteria 3 months after blood collection. The relationship between CTC viability and clinical response was analyzed using a contingency table and Chi-square analysis. Results: The success rate of CTC expansion was 87.2% (48/55), as defined by ATP abundance higher than 3000 U2OS cells after 18 days of culture. Clinical information from 32 of the 50 cases was eligible for analysis, and the results showed that CTC viability at a 70% cutoff correlated with clinical disease control at 3 months after blood collection. The odds ratio, sensitivity, specificity, and diagnostic accuracy were 12 (p = 0.036), 92.3%, 50%, and 79%, respectively. A demonstration of the interaction between this research and the Molecular Tumor Board (MTB) in the Taipei Medical University Healthcare System is presented through a case study of metastatic angiosarcoma and its correlation. Conclusions: The study highlights the potential of using CTC drug sensitivity as a biomarker for precision medicine in STS, despite limitations such as small sample size, short follow-up, and disease and treatment heterogeneity. Advancements in gene-based precision medicine have been made in the past decade, but only a small number of STS patients have seen benefits from it. This emphasizes the need for further research to thoroughly evaluate the potential of CTC drug sensitivity as a predictive biomarker in clinical practice. Key words: soft tissue sarcoma; circulating tumor cells; liquid biopsy; predictive biomarker; precision medicine.

Correlation of drug susceptibility testing on short term cultures of CTCs positively with clinical outcomes in non-small cell lung cancer.

e21177 Background: Enumeration of circulating tumor cells (CTCs) is rapidly emerging as a minimally invasive and reliable technique for monitoring disease progression and patient’s response to treatment. However, its utility beyond enumeration in clinical management of cancer remains scarcely explored. Being biologically similar to both primary and secondary tumors, CTCs may help in identification of most efficacious therapies. In this study, we propose a method for short term culture of CTCs thereby allowing to evaluate the drug susceptibility testing in individual patients. Methods: We obtained peripheral blood samples from 20 advanced stage lung cancer patients undergoing treatment at Kidwai Memorial Institute of Oncology, Bangalore, India. These blood samples were processed and cultured on ellipsoidal microwells maintained at hypoxic conditions (1% O2). The CTC clusters were seeded onto 96 well plates coated with Matrigel and treated with the same drug regimen as the respective patients. The viability of the cells was measured using CellTitre-Glo. Results: Of the 20 samples, tight cluster formation was observed in four samples and drug susceptibility testing was performed. Based on clinical treatment received, we treated CTCs with combination of pemetrexed and carboplatin at respective Cmax concentrations of 5.68 and 3.68 µg/ml. The combination drug treatment resulted in decreased viability of CTCs to 30.7%. Notably, the CT scan images demonstrated significant reduction of pleural effusion in patient following treatment with carboplatin and pemetrexed, thus correlating with our in vitro drug susceptibility finding. Conclusions: In this proof of concept study, we demonstrate the feasibility of utilizing in vitro drug susceptibility testing on CTCs as an approach to guide patient specific chemotherapeutic treatment approaches, thus opening avenues for personalized treatments.

Baits-trap chip for accurate and ultrasensitive capture of living circulating tumor cells.

Accurate analysis of living circulating tumor cells (CTCs) plays a crucial role in cancer diagnosis and prognosis evaluation. However, it is still challenging to develop a facile method for accurate, sensitive, and broad-spectrum isolation of living CTCs. Herein, inspired by the filopodia-extending behavior and clustered surface-biomarker of living CTCs, we present a unique baits-trap chip to achieve accurate and ultrasensitive capture of living CTCs from peripheral blood. The baits-trap chip is designed with the integration of nanocage (NCage) structure and branched aptamers. The NCage structure could "trap" the extended filopodia of living CTCs and resist the adhesion of filopodia-inhibited apoptotic cells, thus realizing the accurate capture (∼95% accuracy) of living CTCs independent of complex instruments. Using an in-situ rolling circle amplification (RCA) method, branched aptamers were easily modified onto the NCage structure, and served as "baits" to enhance the multi-interactions between CTC biomarker and chips, leading to ultrasensitive (99%) and reversible cell capture performance. The baits-trap chip successfully detects living CTCs in broad-spectrum cancer patients and achieves high diagnostic sensitivity (100%) and specificity (86%) of early prostate cancer. Therefore, our baits-trap chip provides a facile, accurate, and ultrasensitive strategy for living CTC isolation in clinical. STATEMENT OF SIGNIFICANCE: A unique baits-trap chip integrated with precise nanocage structure and branched aptamers was developed for the accurate and ultrasensitive capture of living CTCs. Compared with the current CTC isolation methods that are unable to distinguish CTC viability, the nanocage structure could not only "trap" the extended-filopodia of living CTCs, but also resist the adhesion of filopodia-inhibited apoptotic cells, thus realizing the accurate capture of living CTCs. Additionally, benefiting from the "baits-trap" synergistic effects generated by aptamer modification and nanocage structure, our chip achieved ultrasensitive, reversible capture of living CTCs. Moreover, this work provided a facile strategy for living CTC isolation from the blood of patients with early-stage and advanced cancer, exhibiting high consistency with the pathological diagnosis.

Abstract LB179: Automated viable circulating tumor cell (CTC) isolation enables efficient single-cell multi-omics analysis in a clinical setting

Abstract Circulating tumor cells (CTCs) are rare cells found in peripheral blood or other body fluids of cancer patients. Single-cell multi-omics analysis of CTCs can provide critical information and insights for tumor heterogeneity, early detection, residual disease, recurrence, and response and resistance to therapies. However, the adoption of single cell analysis in a clinical setting has been challenging due to complicated and lengthy workflows, lack of automation, low throughput, cell loss, inefficient cell picking, and nucleic acid degradation. To overcome these challenges, we have developed the fully automated LiquidScan liquid biopsy platform as a solution for CTC enrichment and single cell isolation. Whole blood samples were collected from breast, prostate, and lung cancer patients using BioFluidica blood collection tubes. CTCs were enriched with LiquidScan platform coupled with microfluidic affinity selection of rare cells with antibodies against cancer specific surface markers. Cell eluates released from microfluidic chips were further sorted and individual cells were placed into individual wells of PCR plates. The isolated single cells were processed with either whole genome amplification for DNA analysis or pre-amplification of RNA for transcriptome profiling. Cell viability and RNA integrity were assessed for enriched cells post LiquidScan processing. Whole blood samples were directly loaded to microfluidic chips and processed (capture, wash, release and elute) using Hamilton robot for automated processing with no require to red blood cell lysis. The sample processing time was approximately 3 hours with up to 8 samples processed simultaneously. Enriched cells were 70% viable on average post LiquidScan sample processing. The RNA RIN score for the enriched cells was 6 on average. Success rate of DNA amplifications and RNA pre-Amplifications were both over 90% across all samples processed. The LiquidScan platform provides a solution for fast, automated single viable cell isolation making downstream molecular analysis possible in a clinical setting. Protocols for RNA pre-amplification and DNA sequencing including copy number analysis and targeted resequencing have been developed. Single cell DNA methylation and proteomics assay development is in progress. Citation Format: Janet Dickerson, Dylan Dufek, Robbie Huff, Stephenie Jones, Jennifer Barber-Singh, Christopher Brandt, Judy Muller-Cohn, Rolf Muller, Yipeng Wang. Automated viable circulating tumor cell (CTC) isolation enables efficient single-cell multi-omics analysis in a clinical setting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB179.

Abstract 5603: Functional studies on viable circulating tumor cells (v-CTCs) and frequent expression of PD-L1 on v-CTCs in pancreatic cancer

Abstract Introduction: The analysis of CTCs as liquid biopsies provides the possibility to avoid invasive tissue biopsies, with obvious implications in cancer diagnostics and treatments. We tested new methods for v-CTCs detection in patients (pts) with pancreatic cancer (PC), and investigated the clinical potential of v-CTCs in prognosis. We analyzed the PD-L1(L1) expression in primary PC tumors, metastatic lymph nodes (LN) and v-CTCs. Pts and Methods: 7.5 ml of venous blood was collected from 39 PC pts, either upfront surgery (U group) or pre-treatment, consisted of Gem:800mg/m2; and S-1:80mg/m2 given concurrently with IMRT to 60Gy ((NACRT:N group). To detect v-CTCs, we employed a telomerase-specific replication-selective adenovirus expressing GFP. For U group, samples were obtained before/after resection. For N group, samples were obtained before/after NACRT and after resection. To distinguish between leucocyte and cells with either epithelial or mesenchymal origin, cells were stained by anti-CD45, anti-Cytokeratin and anti-Vimentin Abs. GFP-positive and CD45-negative cells were counted as v-CTCs. To assess L1 expression in PC tissues (PC tumors and LN) and on v-CTCs, L1 IHC kit (22C3, for tissues) and anti-human L1 mAb(MIH1, for CTCs) were employed. Results: U group: 24 pts aged 53~85 years (male/female=12/12) were enrolled. 24 pts underwent curative resection. No v-CTCs were detected in 6 pts at both before and after resection, and 5 of 6 pts survived without recurrence. V-CTCs were identified in 18 of 24 pts, and 13 of 18 pts developed liver metastasis. Marked decrease of CTC counts were seen after resection in 10 of 18 pts, but 9 pts developed recurrences. N group: 15 PC pts aged 44~77 years (male/female=4/11) were enrolled. 15 pts underwent curative resection. No v-CTCs at 3 sampling points were detected in 5 pts, and 5 pts survived without recurrences. V-CTCs was identified in 10 of 15 pts, and 4 out of 10 pts developed disease recurrence. Marked increase in CTC counts was observed after NACRT in 5 of 6 CTC-positive pts before NACRT, and 3 of 5 pts developed liver metastasis and died. NACRT may induce tumor cell dissemination into the blood circulation for CTC-positive pts. PD-L1 expression: L1 expression were assessed for 21 pts (U group:18, N group: 3). For PC tumors, L1 molecules were expressed in 12 pts and expression level of these pts were all low (57%, ≥50% [high]=0 pts, 1-49% [low]=12 pts {10%=6, 20%=4, 40%=2}, &amp;lt;1% [negative]=9 pts). For metastatic LNs, metastatic LNs were observed in 14 pts and L1-positive expression in these LNs were detected in only 4 pts (28%, all low expression). On the contrary, the majority of detected v-CTCs clearly expressed L1 molecule (92 CTCs out of 103 detected CTCs were L1-positive=89 %). Conclusions: Viable CTC detection appears as a good prognostic marker. Immunotherapy with anti-PD-1/PD-L1 Abs may target v-CTCs, resulted in improvement of poor prognosis. Citation Format: Masahiro Tanemura, Masaki Kashiwazaki, Kenichi Matsumoto, Kenta Furukawa, Manabu Mikamori, Tadafumi Asaoka, Daisaku Yamada, Shogo Kobayashi, Hidetoshi Eguchi. Functional studies on viable circulating tumor cells (v-CTCs) and frequent expression of PD-L1 on v-CTCs in pancreatic cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5603.

Metastasis risk stratification and response prediction through dynamic viable circulating tumor cell counts for rectal cancer in a neoadjuvant setting.

Distant metastasis (DM) and neoadjuvant treatment response prediction remain critical challenges in the management of locally advanced rectal cancer (LARC). The aim of this study was to investigate the clinical relevance of viable circulating tumor cells (CTCs) for DM or response in patients with LARC in a neoadjuvant setting. The detection of viable CTCs at different stages of treatment was planned for consecutive patients from a prospective trial. The Kaplan-Meier method, Cox proportional hazards model, and logistic regression model were utilized to analyze factors associated with DM or pathological complete response (pCR) and clinical complete response (cCR). Between December 2016 and July 2018, peripheral blood samples from 83 patients were collected before any treatment (median follow-up time, 49.3 months). CTCs were present in 76 of 83 patients (91.6%) at baseline, and more than three CTCs detected in the blood sample was considered high risk. Only the CTC risk group was significantly associated with 3-year metastasis-free survival (MFS) (high risk vs. low risk, 57.1% (95% CI, 41.6-72.6) vs. 78.3% (95% CI, 65.8-90.8), p = 0.018, log-rank test). When all the important variables were entered into the Cox model, the CTC risk group remained the only significant independent factor for DM (hazard ratio (HR), 2.74; 95% CI, 1.17-6.45, p = 0.021). The pCR and continuous cCR rates were higher in patients with a decreased number of CTCs of more than one after radiotherapy (HR, 4.00; 95% CI, 1.09-14.71, P = 0.037). The dynamic detection of viable CTCs may strengthen pretreatment risk assessment and postradiotherapy decision making for LARC. This observation requires further validation in a prospective study.

Abstract 6706: Co-culture of circulating tumor cells (CTCs)-derived 3D organoids and autologous cytotoxic CD8+ T cells: A new functional precision oncology platform

Abstract Greater than 10 million patients succumb to cancer each year. Cancer metastasis is responsible for more than 90% of all cancer-associated deaths due to treatment resistance and increased tumor burden. As a seed for metastases, circulating tumor cells (CTCs) present a new dimension and horizon for clinical doctors in diagnosis, prognosis prediction, treatment monitoring, disease mechanism, and drug development. CTCs could gradually replace tissue biopsies which are painful and may be difficult to obtain depending on tumor location. CTC isolation is feasible after minimally invasive liquid biopsy and provides the basis for a multitude of ex vivo and in vivo studies including establishment of CTCs-derived 2D and 3D cultures. Organoids are miniscule models of tissues that grow in a 3D semisolid extracellular matrix medium with specific growth factors supplied. CTCs-derived 3D organoids play a vital role in precision oncology because they can preserve tumor heterogeneity, imitate the tumor microenvironment (TME), mimic cancer hypoxia in the TME, and maintain cancer and metastasis phenotypes. Cytotoxic CD8+ T cells are the most powerful effectors in the anticancer immune response. We hypothesized that co-culture of CTCs-derived 3D organoids and autologous cytotoxic CD8+ T cells could maximize patient-relevance of laboratory assessment of cancer-treatment immune-system interactions to facilitate precision oncology practice. TellBio’s novel TellDx CTC technology allows for isolation of viable and intact CTCs in liquid biopsies, regardless of cancer type. Unlabeled CTCs were cultured in growth factor reduced Matrigel with organoid culture WENRAS medium. Magnetic beads labeled white blood cells (WBCs) were cultured with T cell culture medium - WBCs and magnetic beads usually separate in three days - cytotoxic CD8+ T cells were isolated with the EasySep™ Human CD8+ T Cell Isolation Kit. CTCs-derived 3D organoids and autologous cytotoxic CD8+ T cells were co-cultured with or without different drug treatments - cytotoxicity was measured with CellTiterGlo® 3D Cell Viability Assay and imaging, and further mechanistic studies were feasible. Our co-culture platform enables us to utilize a patient's peripheral blood or pleural effusions to create a patient-specific, in vivo-like TME and immune microenvironment to model and assess ex vivo responses to investigational and FDA-cleared cancer therapies, and potentially provide oncologists with insights to improve clinical outcomes. Citation Format: Lanlan Zhou, Leiqing Zhang, Lindsey Carlsen, Kelsey E. Huntington, Vida Tajiknia, Andrew George, Arielle De La Cruz, Arunasalam Navaraj, Praveen Srinivasan, Maximilian Schwermann, Benedito A. Carneiro, Wafik S. El-Deiry. Co-culture of circulating tumor cells (CTCs)-derived 3D organoids and autologous cytotoxic CD8+ T cells: A new functional precision oncology platform [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6706.

Application of Drug Testing Platforms in Circulating Tumor Cells and Validation of a Patient-Derived Xenograft Mouse Model in Patient with Primary Intracranial Ependymomas with Extraneural Metastases

Primary intracranial ependymoma is a challenging tumor to treat despite the availability of multidisciplinary therapeutic modalities, including surgical resection, radiotherapy, and adjuvant chemotherapy. After the completion of initial treatment, when resistant tumor cells recur, salvage therapy needs to be carried out with a more precise strategy. Circulating tumor cells (CTCs) have specifically been detected and validated for patients with primary or recurrent diffused glioma. The CTC drug screening platform can be used to perform a mini-invasive liquid biopsy for potential drug selection. The validation of potential drugs in a patient-derived xenograft (PDX) mouse model based on the same patient can serve as a preclinical testing platform. Here, we present the application of a drug testing model in a six-year-old girl with primary ependymoma on the posterior fossa, type A (EPN-PFA). She suffered from tumor recurrence with intracranial and spinal seeding at 2 years after her first operation and extraneural metastases in the pleura, lung, mediastinum, and distant femoral bone at 4 years after initial treatment. The CTC screening platform results showed that everolimus and entrectinib could be used to decrease CTC viability. The therapeutic efficacy of these two therapeutic agents has also been validated in a PDX mouse model from the same patient, and the results showed that these two therapeutic agents significantly decreased tumor growth. After precise drug screening and the combination of focal radiation on the femoral bone with everolimus chemotherapy, the whole-body bone scan showed significant shrinkage of the metastatic tumor on the right femoral bone. This novel approach can combine liquid biopsy, CTC drug testing platforms, and PDX model validation to achieve precision medicine in rare and challenging tumors with extraneural metastases.

Abstract B047: Fluid shear stress enhances the metastatic potential and rapidly alters metabolism of circulating tumor cells

Abstract Background and Purpose: Circulating tumor cells (CTCs) are exposed to mechanical and biochemical stresses including fluid shear stress (FSS), due to blood flow, and oxidative distress, from a lack of matrix attachment. Recently we have shown that viable CTCs actively resist destruction when exposed to FSS by a mechano-adaptive mechanism that depends on RhoA-actomyosin activity (PMID: 32187555). Since the RhoA-actomyosin axis is implicated in other cellular behaviors that might contribute to metastasis, here we explored the hypothesis that exposure to FSS alters the biology of viable CTCs to promote metastatic colonization. Methodology: To determine if exposure to FSS alters metastatic potential, we exposed PC-3 prostate cells to FSS prior to injection into the tail-vein of NCG mice. We then monitored metastasis formation by weekly bioluminescence imaging. We also examined whether FSS exposure altered the ability of PC-3 and MDA-MB-231 cells to invade through a collagen I matrix, as well as their ability to survive/proliferate under anchorage-independent conditions. We conducted GC/LC-MS metabolomic profiling immediately after FSS exposure. To investigate oxidative burden on FSS exposed cells, we used dihydroethidium (10µM, 30 minutes) to measure general ROS production and a lipid peroxide sensor (5µM, 20 minutes). Results: We found that FSS exposure shortens the time for metastasis formation by 20% (median of 42 vs 52.5 days metastasis free; p=0.0222, log-rank). For both PC-3 and MDA-MB-231 cells we found that FSS exposure leads to ~2x increase in invasion through collagen matrix, and that increase depends on RhoA. Moreover, FSS exposure resulted in increased proliferation (~25%) under anchorage independent conditions in both cell lines. Metabolomic profiling revealed that FSS exposure resulted increased glycolysis, reduced entry into the TCA cycle, and a decrease in the metabolites that feed the folate cycle. We blocked glycolysis in PC-3 and MDA-MB-231 cells with 2-deoxyglucose (25mM, 2 hours) and found that this increased the fraction of cells destroyed by FSS ~20-30%. We also investigated redox stress and found that compared to cells held in suspension, those exposed to FSS demonstrate lower ROS burden. Interestingly, cells exposed to FSS exhibit lower levels of lipid peroxides in a manner that depends on RhoA. Conclusion: Our findings demonstrate that brief pulses of FSS exposure can enhance metastatic potential, increase invasive and anchorage-independent proliferative capacity and rapidly alter metabolism. The phenotypic changes driven by exposure to FSS depend in part on RhoA activation but may also reflect other mechanisms by which cancer cells sense and respond to FSS. FSS rapidly alters cellular metabolism in a manner that may act to reduce oxidative distress while CTCs are in suspension. In summary, our data indicate that FSS exposure in the circulation not only represents a physical force that CTCs must overcome to survive, but it also provides instructive cues that may enhance the metastatic behavior of some CTCs. This abstract is being presented as a short talk in the scientific program. A full abstract is available in the Short Talks from Proffered Abstracts section (PR006) of the Conference Proceedings. Citation Format: Devon L. Moose, Amanda N. Pope, Marion Vanneste, Patrick Breheny, Eric B. Taylor, Michael D. HenryDevon L. Moose, Amanda N. Pope, Marion Vanneste, Patrick Breheny, Eric B. Taylor, Michael D. Henry. Fluid shear stress enhances the metastatic potential and rapidly alters metabolism of circulating tumor cells [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B047.

Impact of endoscopic metallic stent placement and emergency surgery on detection of viable circulating tumor cells for acute malignant left-sided colonic obstruction

BackgroundSelf-expanding metal stents (SEMS) served as a bridge to surgery (BTS). However, this method may be associated with worse long-term prognosis and relapse of CRC patients. Therefore, we attempted to clarify this in the angle of circulating tumor cells (CTCs).MethodsA multicenter study was performed from March 2018 to January 2021. Thirty-two colorectal cancer patients with obstruction were selected, of which 21 patients were performed SEMS as a BTS while 11 patients were performed emergency surgery. Bloods samples were collected in two groups of patients for further detecting CTCs. In the SEMS group, the samples were collected before and after stent insert and after radical surgery performed. In the ES group, the samples were collected before stent insert and after emergency surgery performed.ResultsThe number of CTCs did not show statistically significant differences before and after stent placement (34.90 vs 38.33, p=0.90), neither between the SEMS group and ES group in initial CTC levels (34.90 vs 58.09, p=0.394). No significant differences (38.33 vs 58.09, p=0.632) were observed after stent insert in the SMES group and the initial CTC levels in the ES group. Moreover, no major differences (24.17 vs 42.27, p=0.225) were observed after radical operation performed in both groups.ConclusionThe treatment of SEMS does not cause an increase in the number of CTC after stent insertion. Furthermore, there are may be other factors besides CTC to cause these poorer oncologic outcomes after SEMS placement.

Capture and Selective Release of Viable Circulating Tumor Cells.

Selectively capturing and releasing viable circulating tumor cells (CTCs) from the peripheral blood of cancer patients is advantageous for investigating the molecular hallmarks of metastasis and developing personalized therapeutics. CTC-based liquid biopsies are flourishing in the clinical setting, offering opportunities to track the real-time responses of patients during clinical trials and lending accessibility to cancers that are traditionally difficult to diagnose. However, CTCs are rare compared to the breadth of cells that reside in the circulatory network, which has encouraged the engineering of novel microfluidic devices. Current microfluidic technologies either extensively enrich CTCs but compromise cellular viability or sort viable CTCs at low efficiencies. Herein we present a procedure to fabricate and operate a microfluidic device capable of capturing CTCs at high efficiencies while ensuring high viability. The microvortex-inducing microfluidic device functionalized with nanointerfaces positively enriches CTCs via cancer-specific immunoaffinity, while a thermally responsive surface chemistry releases the captured cells by raising the temperature to 37°C.