Dynamics Of Circulating Tumor Cells Research Articles

Frequency and Prognostic Value of Circulating Tumor Cells in Cancer of Unknown Primary.

Cancer of unknown primary (CUP) is defined as a primary metastatic malignancy, in which the primary tumor remains elusive in spite of a comprehensive diagnostic workup. The frequency and prognostic value of circulating tumor cells (CTCs), which are considered to be the source of metastasis, has not yet been systematically evaluated in CUP. A total of 110 patients with a confirmed diagnosis of CUP according to the European Society for Medical Oncology (ESMO) guidelines, who presented to our clinic between July 2021 and May 2023, provided blood samples for CTC quantification using CellSearch methodology. CTC counts were correlated with demographic, clinical, and molecular data generated by comprehensive genomic profiling of tumor tissue. CTCs were detected in 26% of all patients at initial presentation to our department. The highest CTC frequency was observed among patients with unfavorable CUP (35.5%), while patients with single-site/oligometastatic CUP harbored the lowest CTC frequency (11.4%). No statistically significant association between CTC positivity and the number of affected organs (P = 0.478) or disease burden (P = 0.120) was found. High CTC levels (≥5 CTCs/7.5 mL; 12/95 analyzed patients) predicted for adverse overall survival compared to negative or low CTC counts (6-months overall survival rate 90% vs 32%, log-rank P < 0.001; HR 5.43; 95% CI 2.23-13.2). CTC dynamics were also prognostic for overall survival by landmark analysis (log-rank P < 0.001, HR 10.2, 95% CI 1.95-52.9). CTC frequency is a strong, independent predictor of survival in patients with CUP. CTC quantification provides a useful prognostic tool in the management of these patients.

The circulation stage of the metastatic cascade: A mathematical description and its clinical implications

Metastatic cascade is a multi-stage process that starts with separation of a cancer cell from the primary tumor and ends with the emergence of a detectable metastasis. In the process the initiator cancer cell enters the circulatory system (intravasates), flows with the blood, and exits the circulation (extravasates) into an organ or tissue. The time period between intravasation and extravasation constitutes the circulation stage of the metastatic cascade. This stage is unique in that it lends itself naturally to various non-invasive observations and measurements in an individual cancer patient. This creates an opportunity for gaining insight into metastasis, its mathematical modeling, and designing diagnostic/prognostic tools and new cancer therapies. Although mechanisms of intravasation, survival and extravasation of circulating tumor cells (CTCs) are very complex and largely unknown, mathematical modeling of the circulation stage of the metastatic cascade is facilitated by two inter-related factors: a relative simplicity of the circulatory network and the cyclic nature of blood flow. The article presents a single-subject stochastic model of CTC dynamics that leads to simple formulas, applicable to any homogeneous CTC population, for organ-specific extravasation probabilities, the distribution and expected value of the number, X, of circulation cycles completed by a CTC prior to extravasation, and the average circulation time. In particular, we found that the distribution of random variable X is geometric G(x), where parameter x is measurable, at least in principle, in an individual subject. We also discuss implications of our results for cancer research and treatment.

Circulating tumor cells in patients with hormone receptor-positive, HER2-negative metastatic breast cancer receiving palbociclib with fulvestrant after progression on palbociclib with an aromatase inhibitor.

e13018 Background: High levels of circulating tumor cells (CTCs) at initiation of therapy in patients with metastatic breast cancer (MBC) are associated with worse prognosis. In patients with hormone receptor–positive (HR+), HER2-negative MBC, the benefit of maintaining CDK4/6 inhibitor (CDK4/6i) after progression on first-line therapy with endocrine therapy and CDK4/6i is not fully defined. To study the relationship between CTCs, tumor characteristics, and clinical outcomes, we enumerated CTC dynamics in patients with HR+ HER2- MBC enrolled on a phase II, multi-center, open-label interventional trial of palbociclib and fulvestrant after disease progression on prior palbociclib with an aromatase inhibitor (NCT02738866). Methods: Blood samples from study participants were collected at baseline (pretreatment), cycle 2 (C2, 8 weeks after initiation of fulvestrant and palbociclib), and at disease progression. Using a previously analytically validated assay (CellSearch), CTCs were enumerated. Progression-free survival (PFS) was estimated using the Kaplan Meier method. The relationship between CTC count at baseline (&lt; 5, &gt;5/7.5 ml Whole Blood (WB)) and PFS was analyzed using Cox proportional hazards regression. The association between PFS and CTC count among patients with baseline CTC ≥5 was estimated with a Cox proportional hazards model, adjusting for age, race, and progesterone receptor (PgR). Results: Between May 2017 and September 2022, baseline samples were collected from 52 of 60 trial participants enrolled at 5 centers in the United States, mean age 55 years (SD 14). Baseline CTC counts were &lt;5 in 30/52 (58%) and &gt;5 in 22/52 (42%) of participants. Among participants at baseline, only tissue PgR negativity was associated with higher likelihood of having elevated CTCs &gt;5 (p = 0.04). Association of CTCs &gt;5 and select patient and tumor characteristics is shown in Table 1. There was no statistically significant association between continuously measured CTC and PFS among those with elevated CTCs at baseline. Median duration of therapy among the entire 52 participant cohort was 4 months. Median PFS in participants with baseline CTC &lt;5 vs &gt;5/7.5 ml WB was 7.83 (95% CI [5.37, 12.60]) and 2.83 (95% CI [1.77, 4.73]) months, respectively (HR): 2.10, 95% CI [1.15, 3.82], p = 0.01). Conclusions: Baseline CTCs &gt;5/7.5 ml WB conferred a 2-fold increased risk of disease progression. Tissue PgR negativity was associated with baseline CTCs &gt;5. These data can be used to inform new studies in which baseline and early change in CTCs may inform second line treatment decisions in women with HR+, HER2- MBC. [Table: see text]

Circulating tumor cells dynamics during chemotherapy predict survival and response in advanced non-small-cell lung cancer patients.

Circulating tumor cells (CTCs) are prognostic biomarker in non-small-cell lung cancer (NSCLC). CTCs could also be used as predictor of efficacy of systemic treatments in advanced NSCLC. We described the dynamic changes of CTCs during first-line platinum-based chemotherapy in advanced NSCLC and clarified the correlation between CTC counts and efficacy of chemotherapy. Chemotherapy is administered and blood specimens are collected at four time points from baseline to disease progression for CTC detection. This multicenter prospective study enrolled patients with previously untreated stage III or IV NSCLC fit for standard platinum-based chemotherapy. Bloods were sampled as per standard operating procedures at baseline, cycle 1 and cycle 4 of chemotherapy, and at disease progression for CTC analysis using the CellSearch system. Among 150 patients enrolled, median overall survival (OS) was 13.8, 8.4, and 7.9 months in patients with CTC-, KIT-CTC, and KIT+CTC at baseline (p = 0.002). Patients with persistent negative CTC (46.0%) had longer progression-free survival [5.7 months, 95% confidence interval (CI): 5.0-6.5 versus 3.0 months, 0.6-5.4; hazard ratio (HR): 0.34, 95% CI: 0.18-0.67) and OS (13.1 months, 10.9-15.3 versus 5.6 months, 4.1-7.1; HR: 0.17, 0.08-0.36) compared with patients with persistent positive CTC (10.7%), which was not impacted by chemotherapy. Chemotherapy decreased CTC from 36.0% (54/150) to 13.7% (13/95). CTC persistent presence during treatment represents poor prognosis and resistance to chemotherapy in advanced NSCLC. Chemotherapy could effectively eliminate CTCs. Molecular characterization and the functionalization of CTC will be warranted for further intensive investigation. NCT01740804.

Circulating Tumor Cells in Desmoid Tumors: New Perspectives.

IntroductionDesmoid tumor (DT) is a rare neoplasm with high local recurrence rates, composed of fibroblastic cells that are characterized by the expression of key molecules, including the intermediate filament vimentin, cyclooxygenase-2 (COX-2), and nuclear β-catenin, and lack of epithelial markers. Circulating tumor cells (CTCs) isolated from the peripheral blood of patients with sarcomas and other neoplasms can be used as early biomarkers of tumor invasion and dissemination. Moreover, CTCs can also re-colonize their tumors of origin through a process of “tumor self-seeding.”ObjectivesWe aimed to identify CTCs in the peripheral blood of patients with DT and evaluate their expression of β-catenin, transforming growth factor receptor I (TGF-βRI), COX-2, and vimentin proteins.Material and MethodsWe conducted a prospective study of patients with initial diagnosis or relapsed DT with measurable disease. Blood samples from each patient were processed and filtered by ISET® (Rarecells, France) for CTC isolation and quantification. The CTC expression of β-catenin, COX-2, TGF-βRI, and vimentin was analyzed by immunocytochemistry (ICC).ResultsA total of 18 patients were included, and all had detectable CTCs. We found a concordance of β-catenin expression in both CTCs and primary tumors in 42.8% (6/14) of cases by using ICC and immunohistochemistry, respectively.ConclusionsOur study identified a high prevalence of CTCs in DT patients. Concordance of β-catenin expression between primary tumor and CTCs brings new perspectives to assess the dynamics of CTCs in the blood compartment, opening new avenues for studying the biology and behavior of DT. In addition, these results open the possibility of using CTCs to predict DT dynamics at the time of disease progression and treatment. Further studies with larger sample sizes are needed to validate our findings.

Dissecting spatial heterogeneity and the immune-evasion mechanism of CTCs by single-cell RNA-seq in hepatocellular carcinoma

Little is known about the transcriptomic plasticity and adaptive mechanisms of circulating tumor cells (CTCs) during hematogeneous dissemination. Here we interrogate the transcriptome of 113 single CTCs from 4 different vascular sites, including hepatic vein (HV), peripheral artery (PA), peripheral vein (PV) and portal vein (PoV) using single-cell full-length RNA sequencing in hepatocellular carcinoma (HCC) patients. We reveal that the transcriptional dynamics of CTCs were associated with stress response, cell cycle and immune-evasion signaling during hematogeneous transportation. Besides, we identify chemokine CCL5 as an important mediator for CTC immune evasion. Mechanistically, overexpression of CCL5 in CTCs is transcriptionally regulated by p38-MAX signaling, which recruites regulatory T cells (Tregs) to facilitate immune escape and metastatic seeding of CTCs. Collectively, our results reveal a previously unappreciated spatial heterogeneity and an immune-escape mechanism of CTC, which may aid in designing new anti-metastasis therapeutic strategies in HCC.

Abstract LB060: Circulating tumor cells in desmoid tumors

Abstract Introduction: Desmoid tumor (DT) is a rare neoplasm with high local recurrence rates. CTNNB1 mutations are found in most sporadic cases and are located in exon 3, usually in codons 41 or 45 (p.T41A, p.S45F and p.S45P). Circulating tumor cells (CTCs) isolated from the peripheral blood of patients with sarcomas and other neoplasms can be early biomarkers of tumor invasion and dissemination. Moreover, CTCs can also re-colonize their tumors of origin through a process of “tumor self-seeding.” Objectives: To identify CTCs in the peripheral blood of patients with DT; to evaluate their expressions of β- catenin and vimentin proteins. Materials and methods: We conducted a prospective study of patients with initially diagnosed and relapsed DT with measurable disease. Blood samples from each patient were processed and filtered by ISET® (Rarecells, France) for the isolation and quantification of CTCs. The expressions of β -catenin and vimentin in CTCs were analyzed by immunocytochemistry (ICC). Results: A total of 18 patients were included, and all had detectable CTCs. We found a concordance of β-catenin expression in CTCs and in primary tumors in 42.85% of cases by using ICC and immunohistochemistry respectively. Conclusions: Our study identified a high prevalence of CTCs in DT patients. Concordance of β-catenin expression between primary tumor and CTCs bring new perspectives to assess the dynamics of CTCs in the blood microenvironment, opening new avenues for studying the biology and behavior of DT. In addition, these results open the possibility of using CTCs to predict DT dynamics at the time of progression and during treatment. Further studies with larger sample sizes are needed to validate our findings. Citation Format: Alexcia Camila Braun, Fernando Campos, Emne Ali Abdallah, Anna Paula Ruano, Milena Tariki, Fabio Pinto, Celso Abdon de Mello, Vilma Regina Martins, Ludmilla Thome Chinen. Circulating tumor cells in desmoid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB060.

Clinical Relevance of Viable Circulating Tumor Cells in Patients with Metastatic Colorectal Cancer: The COLOSPOT Prospective Study.

Circulating tumor cells (CTCs) allow the real-time monitoring of tumor course and treatment response. This prospective multicenter study evaluates and compares the early predictive value of CTC enumeration with EPISPOT, a functional assay that detects only viable CTCs, and with the CellSearch® system in patients with metastatic colorectal cancer (mCRC). Treatment-naive patients with mCRC and measurable disease (RECIST criteria 1.1) received FOLFIRI-bevacizumab until progression or unacceptable toxicity. CTCs in peripheral blood were enumerated at D0, D14, D28, D42, and D56 (EPISPOT assay) and at D0 and D28 (CellSearch® system). Progression-free survival (PFS) and overall survival (OS) were assessed with the Kaplan-Meier method and log-rank test. With the EPISPOT assay, at least 1 viable CTC was detected in 21% (D0), 15% (D14), 12% (D28), 10% (D42), and 12% (D56) of 155 patients. PFS and OS were shorter in patients who remained positive, with viable CTCs between D0 and D28 compared with the other patients (PFS = 7.36 vs. 9.43 months, p = 0.0161 and OS = 25.99 vs. 13.83 months, p = 0.0178). The prognostic and predictive values of ≥3 CTCs (CellSearch® system) were confirmed. CTC detection at D28 and the D0-D28 CTC dynamics evaluated with the EPISPOT assay were associated with outcomes and may predict response to treatment.

In vivo flow cytometry reveals a circadian rhythm of circulating tumor cells

Circulating tumor cells (CTCs) is an established biomarker of cancer metastasis. The circulation dynamics of CTCs are important for understanding the mechanisms underlying tumor cell dissemination. Although studies have revealed that the circadian rhythm may disrupt the growth of tumors, it is generally unclear whether the circadian rhythm controls the release of CTCs. In clinical examinations, the current in vitro methods for detecting CTCs in blood samples are based on a fundamental assumption that CTC counts in the peripheral blood do not change significantly over time, which is being challenged by recent studies. Since it is not practical to draw blood from patients repeatedly, a feasible strategy to investigate the circadian rhythm of CTCs is to monitor them by in vivo detection methods. Fluorescence in vivo flow cytometry (IVFC) is a powerful optical technique that is able to detect fluorescent circulating cells directly in living animals in a noninvasive manner over a long period of time. In this study, we applied fluorescence IVFC to monitor CTCs noninvasively in an orthotopic mouse model of human prostate cancer. We observed that CTCs exhibited stochastic bursts over cancer progression. The probability of the bursting activity was higher at early stages than at late stages. We longitudinally monitored CTCs over a 24-h period, and our results revealed striking daily oscillations in CTC counts that peaked at the onset of the night (active phase for rodents), suggesting that the release of CTCs might be regulated by the circadian rhythm.

Short-Term Circulating Tumor Cell Dynamics in Mouse Xenograft Models and Implications for Liquid Biopsy.

MotivationCirculating tumor cells (CTCs) are widely studied using liquid biopsy methods that analyze fractionally-small peripheral blood (PB) samples. However, little is known about natural fluctuations in CTC numbers that may occur over short timescales in vivo, and how these may affect detection and enumeration of rare CTCs from small blood samples.MethodsWe recently developed an optical instrument called “diffuse in vivo flow cytometry” (DiFC) that uniquely allows continuous, non-invasive counting of rare, green fluorescent protein expressing CTCs in large blood vessels in mice. Here, we used DiFC to study short-term changes in CTC numbers in multiple myeloma and Lewis lung carcinoma xenograft models. We analyzed CTC detections in over 100 h of DiFC data, and considered intervals corresponding to approximately 1%, 5%, 10%, and 20% of the PB volume. In addition, we analyzed changes in CTC numbers over 24 h (diurnal) periods.ResultsFor rare CTCs (fewer than 1 CTC per ml of blood), the use of short DiFC intervals (corresponding to small PB samples) frequently resulted in no detections. For more abundant CTCs, CTC numbers frequently varied by an order of magnitude or more over the time-scales considered. This variance in CTC detections far exceeded that expected by Poisson statistics or by instrument variability. Rather, the data were consistent with significant changes in mean numbers of CTCs on the timescales of minutes and hours.ConclusionsThe observed temporal changes can be explained by known properties of CTCs, namely, the continuous shedding of CTCs from tumors and the short half-life of CTCs in blood. It follows that the number of cells in a blood sample are strongly impacted by the timing of the draw. The issue is likely to be compounded for multicellular CTC clusters or specific CTC subtypes, which are even more rare than single CTCs. However, we show that enumeration can in principle be improved by averaging multiple samples, analysis of larger volumes, or development of methods for enumeration of CTCs directly in vivo.

Investigating the Interaction Between Circulating Tumor Cells and Local Hydrodynamics via Experiment and Simulations

The biological and mechanical properties of circulating tumor cells (CTCs) in combination with the hemodynamics affect the preference of metastatic sites in the vasculature. Despite the extensive literature on the effects of biological properties on cell adhesion, the effects of hydrodynamic forces on primary attachment remains an active area of research. Using simulations in conjunction with experimentation, we provide new insight into the interplay of CTCs dynamics and local hydrodynamics. A flow experiment of CTC attachment was performed within a bioprinted, double branching endothelialized vessel. Simulations of fluid flow and CTC transport in the reconstructed and idealized bifurcated vessel were respectively performed by HARVEY, our in-house massively parallel computational fluid dynamics solver. HARVEY is based on the lattice Boltzmann and finite element methods to model the fluid and cells dynamics. The immersed boundary method is employed for resolving the fluid-structure interaction. CTC attachment was quantified experimentally at all regions of the complex vessel. The results demonstrate a clear preference for CTCs to attach at the branch points. To elucidate the effect of the vessel topology on the location of attachment, a fluid-only simulation was performed assessing the differences in the hydrodynamics along the vessel. CTC transport in idealized bifurcated vessels was subsequently studied to examine the effects of cell deformability on the local hydrodynamics patterns and, thus, the preference of attachment sites. The current work provides evidence on the correlation of the hydrodynamics forces arising from the vessel topology and CTC properties on the attachment regions.

Clinical relevance of circulating tumor cells in ovarian, fallopian tube and peritoneal cancer

PurposePresence of circulating tumor cells (CTCs) is associated with impaired clinical outcome in several solid cancers. Limited data are available on the significance of CTCs in gynaecological malignancies. The aims of the present study were to evaluate the dynamics of CTCs in patients with ovarian, fallopian tube and peritoneal cancer during chemotherapy and to assess their clinical relevance.Methods43 patients with ovarian, fallopian tube and peritoneal cancer were included into this prospective study. Patients received chemotherapy according to national guidelines. CTC analysis was performed using the CellSearch system prior to chemotherapy, after three and six cycles.ResultsIn 26% of the patients, ≥ 1CTC per 7.5 ml of blood was detected at baseline (17% of patients with de novo disease, compared to 35% in recurrent patients). Presence of CTCs did not correlate with other factors. After three cycles of therapy, CTC positivity rate declined to 4.8%. After six cycles, no patient showed persistent CTCs. Patients with ≥ 1 CTC at baseline had significantly shorter overall survival and progression-free survival compared to CTC-negative patients (OS: median 3.1 months vs. not reached, p = 0.006, PFS: median 3.1 vs. 23.1 months, p = 0.005). When only the subgroup with newly diagnosed cancer was considered, the association between CTC status and survival was not significant (OS: mean 17.4 vs. 29.0 months, p = 0.192, PFS: 14.3 vs. 26.9 months, p = 0.085). Presence of ≥ 1 CTC after three cycles predicted shorter OS in the entire patient cohort (p < 0.001).ConclusionsHematogenous tumor cell dissemination is a common phenomenon in ovarian, fallopian tube and peritoneal cancer. CTC status before start of systemic therapy correlates with clinical outcome. Chemotherapy leads to a rapid decline in CTC counts; further research is needed to evaluate the clinical value of CTC monitoring after therapy.

First-Line Doublet Chemotherapy for Metastatic Triple-Negative Breast Cancer: Circulating Tumor Cell Analysis of the tnAcity Trial.

PurposeCirculating tumor cells (CTCs) are prognostic biomarkers in metastatic breast cancer, but their role in predicting treatment outcomes in metastatic triple-negative breast cancer (mTNBC) is less clear. The tnAcity trial demonstrated a significant progression-free survival (PFS) benefit with nab-paclitaxel (nab-P)/carboplatin (C) over nab-P/gemcitabine (G) or G/C in patients with mTNBC. We assessed the correlation between CTC dynamics and clinical benefit in all patients and by treatment arm.MethodsCTC enumeration, performed using CELLSEARCH technology (Menarini Silicon Biosystems, Huntingdon Valley, PA, USA), was a prespecified exploratory endpoint in the tnAcity trial. Patients with TNBC were categorized based on pre- and post-treatment CTC levels: Group 1 (+ + +; elevated CTCs at baseline and postbaseline), Group 2 (+ ± ±; CTCs elevated at baseline and cleared postbaseline [cycle 3 and/or cycle 5]), or Group 3 (−; no CTCs detected at baseline). The baseline cutoff was ≥1 CTC/7.5 mL for the main analysis; cutoffs of ≥2 and ≥5 CTCs were used for supporting analyses.ResultsThe main analysis included 126 patients (Group 1, n = 24; Group 2, n = 54; and Group 3, n = 48). The median PFS was longer in Group 2 vs Group 1 (8.5 vs 4.7 months; HR, 0.30 [95% CI, 0.17–0.54]). These results were supported by the ≥2- and ≥5-CTC cutoff analyses. The median overall survival rates were 17.8, 16.0, and 9.8 months in Groups 2, 3, and 1, respectively. The overall response rates were 79.6%, 43.8%, and 29.2%, respectively. A numerically higher percentage of patients had CTC clearance during nab-P/C treatment vs nab-P/G or G/C.ConclusionEfficacy outcomes trended positively with chemotherapy-induced elimination of CTCs, suggesting that CTC clearance may predict the chemosensitivity of mTNBC tumors.Trial registrationEudraCT Number: 2013-000113-20; ClinicalTrials.gov number: NCT01881230.

Circulating tumor cells as a response monitor in stage IV non-small cell lung cancer

BackgroundMonitoring circulating tumor cells (CTC) has been shown to be prognostic in most solid malignancies. There is no CTC assay in clinical use for lung cancer therapy monitoring due to inconclusive clinical utility data. Limited data has been published outside of the standard CTC enumerations, regarding clinical significance of phenotypic heterogeneity of CTCs in late stage NSCLC and its ability to correlate with treatment outcomes.MethodsIn 81 patients with stage IV NSCLC, multiple timepoints for CTC analysis were collected after initiation of treatment across 139 lines of therapy using single cell high definition diagnostic pathology imaging of all nucleated cells from 362 peripheral blood samples as a liquid biopsy.ResultsWe analyzed the subset of 25 patients with complete time series data, totaling 117 blood samples, to determine the significance of HD-CTC kinetics during the initiation of treatment. These kinetics follow three distinct patterns: an increase in HD-CTCs with therapy (mean + 118.40 HD-CTCs/mL), unchanged HD-CTCs numbers (stable; mean 0.54 HD-CTCs/mL), and a decrease in HD-CTCs numbers (mean − 81.40 HD-CTCs/mL). Patients with an increasing CTC count during the first 3 months post initiation of new treatment had a better PFS and OS compared to the other groups. There was weak correlation between the absolute number of HD-CTCs at a single time point of therapy and patient outcomes (OS p value = 0.0754). In the whole cohort of 81 patients, HD-CTCs were detected in 51 (63%) patients at initiation of therapy with a median of 2.20 (range 0–509.20) and a mean of 26.21 HD-CTCs/mL (± 15.64).ConclusionsCTCs are identifiable in most patients with stage IV NSCLC. While absolute HD-CTC counts do not correlate with prognosis, the changes in CTC counts were predictive of survival in patients with metastatic lung cancer receiving chemotherapy. The level and dynamics of CTCs indicate very different biological and pharmacological phenomena at different stages of disease and timepoints of treatment, highlighting the complex role of CTCs in cancer research and clinical management.

The change in circulating tumor cells before and during concurrent chemoradiotherapy is associated with survival in patients with locally advanced head and neck cancer.

This study aimed to evaluate the role of baseline circulating tumor cells (CTCs) before and during concurrent chemoradiotherapy and attempted to determine the impacts of CTCs on the outcomes in patients with head and neck squamous cell carcinoma. CTCs were detected using a negative selection strategy and flow cytometry protocol. We observed a significant correlation between baseline CTCs and staging (P = 0.001). The CTC counts were significantly reduced within 2-4 weeks in 47 concurrent chemoradiotherapy responders (P < 0.001). Change of CTC counts correlates with progression-free survival (PFS, P = 0.01) and overall survival (OS, P = 0.01). CTC decline status was an independent prognostic factor in PFS (P = 0.03) and OS (P = 0.05) in multivariate analyses. In chemoradiotherapy responders, CTCs are significantly reduced. CTC decline within the first month indicates a longer PFS and OS, suggesting that the dynamics of CTCs could be more important than CTC number alone.

Molecular Subtype Conversion between Primary and Metastatic Breast Cancer Corresponding to the Dynamics of Apoptotic and Intact Circulating Tumor Cells.

The presence of circulating tumor cells (CTCs), detected as a form of liquid biopsy is associated with poor survival in both early and metastatic breast cancer. Monitoring tumor biology based on intrinsic subtypes delivers treatment-relevant information on the heterogeneity or biomarker conversion between primary and metastatic tumors. This study aimed to correlate the change of the apoptotic and intact CTC counts with mRNA-assessed intrinsic subtype change. Thirty-four breast cancer patients with available triplets of primary tumors, distant metastasis biopsies and data on intact and apoptotic CTC dynamics were included in the analysis. The intrinsic subtype was determined per RT-qPCR quantification of the gene expression ESR1, PGR, ERBB2 and MKI67. Both luminal (p = 0.038) and triple negative (p = 0.035) patients showed a significant downregulation of apoptotic CTCs. Repeated biopsies of distant metastatic sites, as well as determining a potential shift of the intrinsic subtype, combined with data on intact and apoptotic CTC dynamics from liquid biopsies might help personalize systemic therapy and generate additional surrogate markers for successful systemic therapy.

Circulating tumor cells dynamics in pancreatic adenocarcinoma correlate with disease status: Results of the prospective cluster study

OBJECTIVES Previous retrospective studies demonstrated that circulating tumor cells (CTCs) subtypes correlate with overall survival in patients with pancreatic ductal adenocarcinoma (PDAC). Herein, we report results of a prospective observational study on CTCs dynamics to assess their clinical significance. METHODS The CLUSTER study is a prospective longitudinal study on PDAC CTCs dynamics (NCT02974764). Multiple peripheral blood samples were collected from 200 consecutively enrolled patients with presumed PDAC diagnosis. CTCs were isolated and characterized by immunofluorescence. RESULTS Two major CTCs subtypes were identified in PDAC patients: epithelial CTCs (eCTCs) and epithelial/mesenchymal CTCs (mCTCs). Patients who received neoadjuvant chemotherapy had significantly lower total CTCs (tCTCs, P = 0.007), eCTCs (P = 0.007), and mCTCs (P = 0.034), compared with untreated patients eligible for upfront resection. Surgical resection of the primary tumor resulted in significant reduction, but not disappearance, of CTCs burden across all cell subtypes (P < 0.001). In multivariable logistic regression analysis, preoperative numbers of all CTCs subpopulations were the only predictors of early recurrence within 12 months from surgery in both chemo-naive and post-neoadjuvant patients (odds ratio 5.9 to 11.0). Alterations in CTCs were also observed longitudinally, before disease recurrence. A risk assessment score based on the difference of tCTCs increase accurately identified disease recurrence within the next 2 months, with an accuracy of 75% and 84% for chemo-naive and post-neoadjuvant patients, respectively. CONCLUSION We report novel findings regarding CTCs from a large prospective cohort of PDAC patients. CTCs dynamics reflect progression of disease and response to treatment, providing important information on clinical outcomes, not available by current tumor markers and imaging.

Circulating Tumor Cells Dynamics in Pancreatic Adenocarcinoma Correlate With Disease Status: Results of the Prospective CLUSTER Study.

Previous retrospective studies demonstrated that circulating tumor cells (CTCs) subtypes correlate with overall survival in patients with pancreatic ductal adenocarcinoma (PDAC). Herein, we report results of a prospective observational study on CTCs dynamics to assess their clinical significance. The CLUSTER study is a prospective longitudinal study on PDAC CTCs dynamics (NCT02974764). Multiple peripheral blood samples were collected from 200 consecutively enrolled patients with presumed PDAC diagnosis. CTCs were isolated and characterized by immunofluorescence. Two major CTCs subtypes were identified in PDAC patients: epithelial CTCs (eCTCs) and epithelial/mesenchymal CTCs (mCTCs). Patients who received neoadjuvant chemotherapy had significantly lower total CTCs (tCTCs, P = 0.007), eCTCs (P = 0.007), and mCTCs (P = 0.034), compared with untreated patients eligible for upfront resection. Surgical resection of the primary tumor resulted in significant reduction, but not disappearance, of CTCs burden across all cell subtypes (P < 0.001). In multivariable logistic regression analysis, preoperative numbers of all CTCs subpopulations were the only predictors of early recurrence within 12 months from surgery in both chemo-naive and post-neoadjuvant patients (odds ratio 5.9 to 11.0). Alterations in CTCs were also observed longitudinally, before disease recurrence. A risk assessment score based on the difference of tCTCs increase accurately identified disease recurrence within the next 2 months, with an accuracy of 75% and 84% for chemo-naive and post-neoadjuvant patients, respectively. We report novel findings regarding CTCs from a large prospective cohort of PDAC patients. CTCs dynamics reflect progression of disease and response to treatment, providing important information on clinical outcomes, not available by current tumor markers and imaging.

AB015. S015. Circulating tumor cells dynamics in pancreatic adenocarcinoma correlate with disease status: data from a prospective trial

AB015. S015. Circulating tumor cells dynamics in pancreatic adenocarcinoma correlate with disease status: data from a prospective trial

Molecular signatures of circulating melanoma cells for monitoring early response to immune checkpoint therapy

A subset of patients with metastatic melanoma have sustained remissions following treatment with immune checkpoint inhibitors. However, analyses of pretreatment tumor biopsies for markers predictive of response, including PD-1 ligand (PD-L1) expression and mutational burden, are insufficiently precise to guide treatment selection, and clinical radiographic evidence of response on therapy may be delayed, leading to some patients receiving potentially ineffective but toxic therapy. Here, we developed a molecular signature of melanoma circulating tumor cells (CTCs) to quantify early tumor response using blood-based monitoring. A quantitative 19-gene digital RNA signature (CTC score) applied to microfluidically enriched CTCs robustly distinguishes melanoma cells, within a background of blood cells in reconstituted and in patient-derived (n = 42) blood specimens. In a prospective cohort of 49 patients treated with immune checkpoint inhibitors, a decrease in CTC score within 7 weeks of therapy correlates with marked improvement in progression-free survival [hazard ratio (HR), 0.17; P = 0.008] and overall survival (HR, 0.12; P = 0.04). Thus, digital quantitation of melanoma CTC-derived transcripts enables serial noninvasive monitoring of tumor burden, supporting the rational application of immune checkpoint inhibition therapies.