Median Circulating Tumor Cells Count Research Articles

Abstract B014: Prospective analysis of circulating tumor cell dynamics during preoperative radiotherapy in locally advanced breast cancer

Abstract Introduction: This is a per-protocol interim analysis of circulating tumor cell (CTC) dynamics among patients diagnosed with locally advanced breast cancer receiving preoperative radiotherapy (RT) on the TOPAz trial (“Trial of Preoperative Radiation”) with concurrent enrollment on a prospective observational cohort study (2022-0601). Methods: Eligible patients with clinical or pathologic T3-4 or node-positive non-metastatic breast cancer were prospectively enrolled. All patients received preoperative RT followed by mastectomy and were randomized to conventional fractionation (CFx, 50Gy/25Fx) versus hypofractionation (HFx, 40Gy/15Fx). CTCs were enumerated using the CellSearch® assay immediately prior to RT (Pre-RT) and within 1 week of completing RT (End of RT). Rates of CTC detection and clearance with RT were calculated. Results: As of August 2024, 46 enrolled patients had a Pre-RT assessment for CTCs, of which 45 (98%) received neoadjuvant chemotherapy (NAC), 30 (65%) had clinical T3-4 disease, 10 (22%) had advanced nodal (cN3) disease, 39 (85%) had estrogen receptor (ER)- positive disease, 3 (7%) overexpressed Her2, and 6 (13%) had triple negative disease. Prior to RT, 15 (33%) patients had ≥1 detectable CTC (median [IQR] = 2 cells [1-2.5]). Of the 14 CTC- positive patients with a completed “End of RT” blood draw to date, 11 (79%) achieved CTC clearance, while 3 patients had persistent CTCs (median [IQR] = 2 cells [1.5-2.5]). Patients who achieved CTC clearance had significantly lower median initial CTC count compared to patients who had persistent CTCs ((2 [1-2]) versus 8 [5-19], Kruskal-Wallis test, p<0.05). CTC status at either time point was not significantly associated with clinicopathologic or treatment variables. Of the 9 CTC-positive patients who achieved CTC clearance and completed surgery, 1 experienced pCR (11%) while all 3 patients with persistent CTCs had residual disease. The median RCB index score for patients without detectable CTCs at End of RT (n=33) was 2.9 [1.4- 3.4] versus 3.3 [2.2-3.4] for the 3 patients with persistent CTCs. In a subgroup of 37 patients with ER+ Her2- disease, 11 (30%) patients had detectable CTCs prior to RT. Of the 10 with completed “End of RT” blood draw to date, 8 (80%) achieved CTC-clearance. The median RCB index score for patients without detectable CTCs at End of RT (n=27) was 3.0 [1.5-3.6] versus 3.4 [3.4-3.4] for the 2 patients with persistent CTCs. Conclusion: In this prospective analysis of CTC dynamics during preoperative RT for patients with locally advanced breast cancer, one- third of patients had detectable CTCs prior to RT (33%). Following comprehensive RT, 79% of patients with detectable CTCs prior to RT experienced CTC clearance prior to surgical resection. All patients with persistent CTCs had residual disease at surgery. These interim results support further study of longitudinal monitoring of circulating tumor material as a potential real-time biomarker for residual locoregional disease in the preoperative setting. Citation Format: Chelain R Goodman, Simona F Shaitelman, Saleh Ramezani, Jonathan B. Strauss, Anam Zia, Nathan Comeaux, Ritupreet Virk, Ruitao Lin, Kevin Nead, Melissa P Mitchell, Karen E Hoffman, Eric Strom, Michael Stauder, George Perkins, Valerie Reed, Elizabeth Bloom, Melissa Joyner, Pamela Schlembach, Vicente Valero, Bora Lim, Carlos H Barcenas, Anthony Lucci, Wendy A Woodward, Benjamin D Smith. Prospective analysis of circulating tumor cell dynamics during preoperative radiotherapy in locally advanced breast cancer [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr B014.

The capture of circulating tumor cells by Labyrinth system as a tool for early stage lung cancer detection.

We focus on utilizing the Labyrinth system for the detection of circulating tumor cells (CTCs) in patients with lung nodules. Our aim is to evaluate CTCs isolated through the Labyrinth system as a biomarker for early-stage lung cancer (LC) detection. 167 patients with low dose computed tomography (LDCT) diagnostic results for lung nodules and 31 healthy volunteers (HV) were enrolled. Blood samples were processed for CTC detection. LDCT positive (LDCT+) patients underwent surgery and were categorized into those with LC and those with benign lung diseases (BLD) based on their biopsy results. BLD Patients, LDCT negative (LDCT-) patients and HV served as controls. The correlation of CTC counts with LC, BLD, LDCT- and HV was investigated. Receiver operating characteristic (ROC) curves were used to assess the Labyrinth system's diagnostic potential for early-stage LC. Median CTC counts for LC, BLD, LDCT- and HV were 2.7 CTC/mL, 0.6 CTC/mL, 0.4 CTC/mL, 0 CTC/mL, respectively. Statistical analysis indicated CTC counts could distinguish LC from BLD, LDCT- and HV (p-Values < 0.001). Using a cut-off of 1 CTC/mL, the study showed 84.4% sensitivity and 82.4% specificity for LDCT+ patients. Specificity increased to 85.9% for patients with lung nodules and 88.2% for all participants. In conclusion, CTCs detected by the Labyrinth system can serve as a biomarker for early-stage LC detection for patients with lung nodules. CTCs identified by the Labyrinth system are a promising biomarker for early-stage LC detection in clinical practice.

Detection of circulating tumor cells in non-metastatic prostate cancer through integration of a microfluidic CTC enrichment system and multiparametric flow cytometry.

Prostate cancer (PCa) is the second most common cancer among men and the fifth leading cause of cancer death. Circulating tumor cell (CTC) enumeration and characterisation in PCa has been shown to provide valuable information on prognosis of disease, therapy management and detection of resistance. Here, Cellsway's microfluidic platform for high-throughput enrichment of intact CTC populations was used to isolate CTCs from the blood of 20 localised PCa patients and 10 healthy donor samples to evaluate the clinical performance of the technology. To enumerate and characterise CTCs, a multi-parameter flow cytometry analysis was performed on the enriched CTC suspension using CTC-specific biomarkers. CTCs were detected in 17 of 20 patient samples, which corresponds to 85% CTC positivity. The median CTC count per 7.5 ml blood was 2 (1-9). In 80% of patients (n = 16), the number of CTCs ranged from 1 to 5, and in 5% of patients (n = 1) the number of CTCs was above 5. No CTCs were observed in the blood samples of 10 healthy volunteers, demonstrating the high specificity and low risk of false positives of the technology.

Abstract PO3-16-02: Trastuzumab and taxane chemotherapy in the first-line in MBC patients with a HER2-negative primary tumor and HER2-positive circulating tumor cells: a phase II trial

Abstract Purpose: HER2 overexpressing circulating tumor cells (CTCs) are observed in up to 20% of HER2-negative metastatic breast cancer patients. Since targeted anti-HER2 therapy has drastically increased the outcome of patients with HER2 positive breast cancer, we hypothesized that patients with HER2 overexpressing CTCs might benefit from the addition of trastuzumab to chemotherapy. Methods: In this single-arm, phase II trial, HER2 negative patients with HER2-positive CTCs received trastuzumab as addition to first-line treatment with taxane chemotherapy (trastuzumab group). Patients with detectable CTCs but without HER2 overexpression and that received taxane chemotherapy only, were used as internal control group (taxane monotherapy group). The primary outcome measure was progression-free rate at 6 months (PFR6). The study was powered to reach a PFR6 of 80%; in this case this strategy was considered worth further investigation. In November 2022, the study was terminated early due to slow patient accrual. Results: 63 HER2 negative patients with metastatic disease were screened, of which 8 patients had HER2-positive CTCs and were treated in the first line with trastuzumab in addition a taxane. Patients receiving taxane monotherapy were used as a control group (n = 27). The median number of CTCs was 15 (range 1 – 131) in patients with HER2-positive CTCs, compared to median 5 (range 1-1047) in the control group. PFR6 was 50% in the trastuzumab group and 64% in the taxane monotherapy group, with no significant difference in median PFS (8 versus 9 months, p=0.51). Excluding the patients that had no measurable CTCs, there was a borderline significant difference between median CTC count in the patients that did and that did not have HER2 positive CTCs (p=0.05). We confirmed a significant higher CTC-count in samples that had at least one HER2-postive CTC in an independent patient set (n=233, p&amp;lt; 0.001). Conclusions: Although this study was performed in a limited number of patients, no clinical benefit of trastuzumab was observed. Firstly, we conclude that our strategy was not feasible for clinical implementation due to high numbers needed to screen. And, second, due to the strong correlation between CTC numbers and detected CTC HER2 positivity, the prognostic value of the CTC numbers precludes judgement of any predictive value of the HER2 status of CTCs. Citation Format: Noortje Verschoor, Manouk Bos, Inge de Kruijff, Ngoc M Van, Jaco Kraan, Jan Drooger, Johanna Zuetenhorst, Saskia M Wilting, Stefan Sleijfer, Agnes Jager, John WM Martens. Trastuzumab and taxane chemotherapy in the first-line in MBC patients with a HER2-negative primary tumor and HER2-positive circulating tumor cells: a phase II trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-16-02.

Abstract 7500: Distribution and prognostic significance of circulating tumor cells (CTCs) and tumor-derived extracellular vesicles (tdEVs) in patients (pts) with lobular metastatic breast cancer (MBC)

Abstract Background: Invasive lobular carcinoma (ILC) has distinctive clinical and molecular features compared with invasive ductal carcinoma (IDC). CTCs and tdEVs are independent prognostic factors in MBC, however, liquid biopsy studies focusing on ILC are to date scarce. Higher CTC levels have been observed in ILC than IDC. One study including 28 ILC pts suggested the use of higher CTC cutoff for prognosis stratification. The clinical significance of tdEVs in ILC is unexplored. This study aimed to assess differences in the distribution and prognostic value of CTCs and tdEVs between ILC and IDC. Methods: Blood samples were collected from 304 pts with MBC before starting a new line of therapy at Northwestern University (Chicago, IL) between 2016 and 2021 (NU16B06 trial). Blood was processed with the CellSearch® system. The ACCEPT software was applied to CellSearch® images to automatically enumerate CTCs and tdEVs. Association of CTCs and tdEVs with overall survival (OS) was tested in ILC and IDC pts. A count of CTCs ≥ 5 was considered high. The cutoff levels for tdEVs were &amp;lt; 20 (low), 20-79 (intermediate), and ≥ 80 (high), as previously reported. Additional exploratory cutoffs for CTCs (≥ 20, ≥ 50, ≥ 80, and ≥ 100) and tdEVs (based on quartiles of tdEV distribution in the overall population and ILC) were also evaluated. Results: Of the 304 pts, 47 had ILC while 257 had IDC. 56% of pts received first-line therapy. Median CTC count was 8 [interquartile range (IQR) 2-35] in ILC and 1 (IQR 0-8) in IDC pts (P &amp;lt;.001). A significantly higher median tdEVs count was observed in ILC (36; IQR 18-115) than in IDC (11; IQR 2-86) pts (P =.002). High levels of CTCs (≥5) were not associated with OS in ILC (P =.88), even when higher cutoffs (≥ 20, ≥ 50, and ≥ 80) were used. Only the detection of ≥ 100 CTCs was significantly associated with OS in ILC pts (median OS 36 vs 10 months; HR 3.4; P =.028). In contrast, the prognostic effect of CTCs ≥ 5 was strong in IDC and maintained for all cutoffs. Similarly, while the prognostic value for tdEVs was confirmed for IDC using both 20-80 and exploratory cutoffs (3-105 and 18-155), no association between tdEV levels and OS was observed in ILC regardless of the cutoffs used. Conclusion: ILC is associated with higher CTCs and tdEVs compared to IDC, probably due to the impaired cell-cell adhesion that characterizes ILC. Unlike IDC, the prognostic effect for the established cutoff of ≥ 5 CTC was not observed in ILC. A higher CTC cutoff could be considered for this subtype of BC. For tdEV no association with OS was observed, regardless of the cutoff used. These findings emphasize that ILC is a distinct entity also in the liquid biopsy features. Because of the low prevalence of ILC, research efforts should be directed at combining data from ILC pts to better characterize this subtype of BC and understand the reason behind the different associations with OS as compared to IDC. Citation Format: Eleonora Nicolo, Lorenzo Gerratana, Lorenzo Foffano, Laura Munoz-Arcos, Mara S. Serafini, Maroua Manai, Letizia Pontolillo, Nadia Bayou, Elisabetta Molteni, Amanda K. Strickland, Caterina Gianni, Youbin Zhang, Paolo D'Amico, Andrew A. Davis, Jeannine Donahue, Huiping Liu, William J. Gradishar, Ami N. Shah, Giuseppe Curigliano, Carolina Reduzzi, Massimo Cristofanilli. Distribution and prognostic significance of circulating tumor cells (CTCs) and tumor-derived extracellular vesicles (tdEVs) in patients (pts) with lobular metastatic breast cancer (MBC) [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 7500.

Analyzing circulating tumor cells and epithelial-mesenchymal transition status of papillary thyroid carcinoma patients following thyroidectomy: a prospective cohort study.

This study investigated the prevalence and subtype distribution of circulating tumor cells (CTCs) in patients with papillary thyroid cancer (PTC) before and after thyroidectomy to determine the potential of CTC count as a non-invasive marker of the efficacy of surgical treatment in PTC. Between January 2021 and January 2022, 62 PTC patients who underwent thyroidectomy at OOOOOOO Hospital were prospectively evaluated. Peripheral blood samples (7.5ml) were collected from each patient for CTC analysis before surgery and at 2 weeks and 3 months after surgery. CTC count and the distribution of CTC subtypes, including epithelial, epithelial-mesenchymal, and mesenchymal phenotypes, were analyzed using the negative selection method and immunofluorescence staining. The relationship between CTC count and clinicopathological characteristics was analyzed before and after surgery. Before surgery, CTCs were detected in 87% (54/62) of patients; the mean CTC count was 8.0 and the median was 5.0 in 7.5ml of peripheral blood. The mesenchymal or epithelial-mesenchymal phenotypes were predominant. After thyroidectomy, the mean and median CTC count values decreased to 5.3 and 2.5, respectively, at 2 weeks and to 4.3 and 3.0, respectively, at 3 months. This postoperative reduction in CTCs was more pronounced in patients with lymphatic invasion, lymph node metastasis, or BRAF V600E mutation. CTCs were detected in patients with PTC with a predominance of cells undergoing epithelial-mesenchymal transition. The CTC count decreased postoperatively, suggesting that liquid biopsy with CTC detection could be a valuable non-invasive tool for monitoring the efficacy of surgery in PTC.

Prognostic value of tumor-derived extracellular vesicles and circulating tumor cells in metastatic breast cancer (BC): A focus on inflammatory BC.

1098 Background: Circulating tumor cells (CTCs) are an independent prognostic factor in metastatic breast cancer (MBC). The prognostic value of CTCs and the optimal cutoff for patients (pts) with inflammatory breast cancer (IBC), one of the most aggressive types of BC, has not been fully established. Recent evidence showed the complementary prognostic value of tumor-derived extracellular vesicles (tdEVs) to CTCs in MBC. The significance of tdEVs in IBC is unexplored. This study aimed to assess the prognostic value of CTCs and tdEVs in metastatic IBC. Methods: This study retrospectively analyzed 308 pts with MBC enrolled at Northwestern University (Chicago, IL) before starting a new line of therapy between 2016 and 2021 (NU16B06 trial). Blood samples were processed for CTCs using the CellSearch system. We applied the open source ACCEPT software to archived CellSearch images to enumerate CTCs and tdEVs. TdEVs cutoff levels were &lt;20 (low), 20-79 (intermediate), and ≥80 (high), as previously reported. The association of CTCs and tdEVs with overall survival (OS) was tested in the overall population (OvP) and IBC pts. Results: Of the 308 pts, 69 were diagnosed with IBC. 51% of pts received first-line therapy. CTCs enumerated by ACCEPT were strongly correlated with manual count (r=0.86) and hence used for this analysis. Median CTC count was 1 [interquartile range (IQR) 0-7] in IBC pts and 3 (IQR 0-14) in non-IBC (p=0.11). A significantly lower median tdEVs count was observed in IBC (7; IQR 3-45) than in non-IBC (22; IQR 4-137) pts (p=0.03). In IBC, higher CTC and tdEV counts were seen in the triple negative subtype (p=0.03) and non-visceral involvement (p=0.02), respectively. In the OvP median OS (mOS) was worse among pts with ≥5 CTCs (HR 2.6; p=0.001) and with elevated tdEVs (HR 3.3; p&lt;0.001). Only tdEVs were independently associated with poorer OS in multivariable analysis. In pts with &lt;5 CTCs there was a stepwise decrement in OS with increased tdEVs count (p=0.3); in pts with ≥5 CTCs, elevated tdEVs levels were associated with significantly worse OS (p=0.03). IBC pts with ≥5 CTCs had shorter mOS (8 vs 47 months; HR 3.6; p&lt;0.001); this association was weaker using ≥1 as CTC cutoff (HR 2.4; p=0.01). OS was adversely associated with increasing tdEVs levels (33 vs 23 vs 7 months for low, intermediate, and high subgroups, respectively; HR 3.7; p=0.001). Furthermore, elevated tdEVs were associated with shorter mOS in pts with ≥1 (p=0.055) and ≥5 CTCs (p=0.6). Among pts with &lt;5 CTCs no significant difference emerged among tdEVs subgroups (p=0.6). Conclusions: This study confirmed the strong prognostic significance of CTCs and tdEVs in MBC, including IBC. Pts with IBC had fewer CTCs and tdEVs compared to non-IBC, probably due to the predominant lymphatic spread of IBC. tdEVs offer the possibility to better define prognosis of IBC pts. Further studies are needed to evaluate their complementarity to CTCs.

Perioperative change of circulating tumor cells in cytoreductive radical prostatectomy for oligometastatic hormone-sensitive prostate cancer: the preliminary safety evidence from long-term oncologic outcomes.

Surgical manipulation has a risk of triggering the shedding of circulating tumor cells (CTCs) in patients with malignancies, However, perioperative change of circulating tumor cells in cytoreductive radical prostatectomy (CRP) for patients with oligometastatic hormone-sensitive prostate cancer (omHSPC) has not yet been well documented. This study aimed to assess whether CRP is a safe procedure for patients with omHSPC by monitoring the perioperative change of CTCs and investigating its impact on long-term oncologic outcomes. We have observed a significant decrease between the median CTC counts before and after surgery (6 vs. 4, p = 0.026). Comparing preoperative and postoperative CTC levels, seven patients increased (CTC increase group), one did not change and nineteen decreased (CTC non-increase group). PSA response rates in CTC increase group were lower than those in CTC non-increase group (73.0% vs 99.8%, p = 0.162), and nadir PSA was higher in CTC increase group (0.043 vs 0.003, p = 0.072). The CTC increase was positively correlated with the nadir PSA (r = 0.386, p = 0.047). The median follow-up period was 71.6months, we found that there was no significant difference in clinical-pathological, operative variables or long-term oncologic outcomes between perioperative CTC increase and non-increase groups. In the entire cohort, the CTC level significantly decreased after surgery. There was no significant differences in long-term oncologic outcomes between the CTC increase and non-increase groups, implying that CRP potentially represents a safe procedure for the treatment of patients with omHSPC. The results need to be confirmed in a prospective large-scale clinical trial.

The prognostic value of chemotherapy or endocrine therapy choice according to circulating tumor cell count in HR+HER2- metastatic breast cancer: a retrospective study.

BackgroundCirculating tumor cell (CTC) count have prognostic role for metastatic breast cancer (MBC). No clear biomarkers can guide selection of chemotherapy (CT) or endocrine therapy (ET) in 1st-line setting of hormone-receptor positive and human epidermal growth factor receptor 2 negative (HR+HER2−) MBC. The present study investigated the prognostic role CT or ET according to the CTC count in HR+HER2− MBC.MethodsWe consecutively collected the data of 53 HR+HER2− MBC patients who received 1st-line CT or ET, who had CTC count detected by our peptide-based nanomagnetic CTC isolation system (Pep@MNPs) from January 2014 to December 2015. The clinicopathological characteristics according the CTC count and 1st-line ET vs. CT were compared. Follow-up was conducted every 6 months. The primary endpoint was progression-free survival (PFS) and overall survival (OS). A Cox regression analysis was conducted to determine the prognostic roles of CTC and 1st-line therapy of ET vs. CT for PFS and OS.ResultsThe median CTC count of the 53 patients was 2 (range, 0–18). The clinicopathological characteristics of the patients in the CTC count <2 group and the CTC count ≥2 group were similar. The patients with a CTC count <2 had a significantly longer PFS than those with a CTC count ≥2 (P=0.005, hazard ratio =4.138, 12.1 vs. 7.1 months). The patients who received CT had a significantly longer PFS than those who received ET (P=0.041, hazard ratio =2.721, 9.9 vs. 7.2 months). In the CTC count ≥2 group, the patients who received CT had a significantly longer PFS than those who received ET (P=0.048, hazard ratio =2.475, 8.7 vs. 6.3 months). In the CTC count <2 group, there was no significant difference in PFS between the CT and ET groups (P=0.071). Additionally, the CTC count had no significant effect on OS (P=0.116, hazard ratio =2.391, 54.2 vs. 34.2 months).ConclusionsThe present study showed that CTC count determined by the Pep@MNP system confirmed the prognostic value in the HR+HER2− MBC patients. And it might be helpful in choosing a 1st-line treatment of CT or ET for HR+HER2− MBC patients.

Early ligation of the pulmonary vein can reduce the dissemination of shed tumor cells during thoracoscopic lobectomy

ObjectiveThe sequence of vessel ligation in lobectomy can significantly affect the hematogenous spread of circulating tumor cells (CTCs). Vein-first ligation substantially reduces CTC dissemination and achieves favorable survival compared with artery-first ligation. In this study, we further explored whether the timing of pulmonary vein (PV) ligation determined according to the early and late PV ligation technique is associated with CTC dissemination. MethodsA total of 44 patients who underwent uniform 2-port video-assisted thoracoscopic surgery lobectomy were enrolled; the subjects were divided into the early ligation group (n = 18) and late ligation group (n = 26) according to whether PV ligation was prioritized during surgery. PV blood was obtained before PV ligation and after lobe resection. CTCs were detected using telomerase reverse transcriptase-based CTC detection and validated using FlowSight and fluorescence in situ hybridization. ResultsThe median postoperative PV CTC (Post-PVCTC) count was 9 (interquartile range [IQR], 6-18), which was higher than the median preoperative PV CTC (Pre-PVCTC) count of 1 (IQR, 0-3; P < .001). Clinicopathologic correlation analysis showed that the Pre-PVCTC count correlated positively with TNM stage (P = .002) and lymph node metastasis (P = .002) and that the Post-PVCTC count correlated positively with tumor density (P = .043) and vessel/lymphatic invasion (P < .030). Interestingly, although no statistical difference in the median Pre-PVCTC count was observed, the median Post-PVCTC count in the early ligation group was 16 (IQR, 9.5-36.75), whereas that in the late ligation group it was 8 (IQR, 4.75-12.25), showing a significant difference (P = .004). ConclusionsWe provide the first evidence to show that early PV ligation can prevent PVCTCs from spreading into the circulation, offering an innovative surgical concept for the principle sequence of pulmonary vessel management.

Presence of CD133-positive circulating tumor cells predicts worse progression-free survival in patients with metastatic castration-sensitive prostate cancer.

ObjectiveTo investigate the clinical significance of the expression of the stemness marker CD133 in circulating tumor cells of newly diagnosed metastatic castration‐sensitive prostate cancer patients.MethodsFor this study, 104 metastatic castration‐sensitive prostate cancer patients treated at the Fudan University Shanghai Cancer Center from September 2015 to February 2017 were considered. After enrollment, the patients received androgen deprivation therapy (bicalutamide + goserelin). Circulating tumor cells were isolated and identified using the CanPatrol system, which can identify not only traditional epithelial markers but also mesenchymal markers in cells that have undergone epithelial mesenchymal transition. CD133 was used to characterize the circulating tumor cells. The primary endpoint of this research was to evaluate progression to castration resistance.ResultsAmong the 104 patients enrolled, 89 patients were circulating tumor cell positive at baseline, and the median circulating tumor cell count was four. The median follow‐up was 24 months, and at the end of follow‐up, the proportion of patients who progressed to castration‐resistant prostate cancer in the CTC+CD133+ group was 93.3%, which was significantly higher than that of the circulating tumor cell negative group (73.3%) and the CTC+CD133− group (75.0%), with P = 0.043. After follow‐up, progression‐free survival for CTC+CD133+, CTC+CD133−, and circulating tumor cell patients was 10.0, 13.0, and 14.0 months, respectively, with P = 0.022. Univariate and multivariate analyses also confirmed that the characterization of circulating tumor cells using CD133 can independently predict progression‐free survival in metastatic castration‐sensitive prostate cancer patients after receiving androgen deprivation therapy (P = 0.042; hazard ratio 1.396).ConclusionBaseline CTC+CD133+ was a poor independent prognostic factor for metastatic castration‐sensitive prostate cancer patients to progress to castration‐resistant prostate cancer after receiving androgen deprivation therapy.

OA09.03 Pembrolizumab in Combination With Platinum-Based Chemotherapy in Recurrent EGFR/ALK-Positive Non-Small Cell Lung Cancer (NSCLC)

Efficacy of single-agent immune checkpoint inhibitors is limited in patients with EGFR/ALK-altered NSCLC. We conducted a phase II study to assess the efficacy of pembrolizumab in combination with carboplatin and pemetrexed in these patients. Patients with recurrent EGFR-mutated or ALK-rearranged NSCLC, previously treated with targeted therapy, were eligible. Patients were treated with carboplatin AUC5, pemetrexed 500 mg/m2 and pembrolizumab 200 mg I.V. every 3 weeks. After 4 cycles patients were maintained on pemetrexed and pembrolizumab for up to 2 years. Disease was assessed every 2 cycles for the first 6 cycles, then per investigator discretion. The primary end-point was RECIST 1.1 defined response rate. Secondary endpoints included PFS and OS. Tumor PD-L1 expression was assessed locally. Blood for circulating tumor cells (CTCs) was collected prior to the 1st and 3rd cycles. The plan was to enroll 28 evaluable patients in each of two separate cohorts of EGFR-mutated and ALK-rearranged NSCLC. Slow enrollment led to early termination of the trial. Of the 33 patients enrolled, 26 had EGFR-mutated NSCLC (13 del19, 9 L858R), 64% were female and median age was 67 years. The median number of prior treatments was 1 (range 1-3). 22 of 26 EGFR+ NSCLC patients had received prior osimertinib. Median number of cycles was 6 (2-24 cycles), with 4 patients, all EGFR+, still on therapy. Response rates (95%CI) were 42% (23%, 63%) and 29% (4%, 71%) among EGFR+ and ALK+ patients, respectively. Median duration of response was 6.1 months in all patients and in EGFR+ patients. Other efficacy results are provided below. Tumor PD-L1 expression was available for 30 patients and was ≥ 1% in 17. There was no difference in survival between patients with tumor PD-L1 <1% vs. ≥ 1%. The median CTC count at baseline in 15 EGFR+ patients in whom samples were available was 4/ml (0-23). Median overall survival among EGFR+ patients with decreased vs. increased CTC count during treatment was not reached vs. 18.5 months, respectively (p=0.52 for OS). The most common adverse events were fatigue, nausea, cytopenias, cough and dyspnea. The most common ≥ grade 3 toxicities were neutropenia, thrombocytopenia, thromboembolism, and AST/ALT elevation. One patient developed pneumonitis.TableEFGR+ (n=26)ALK+ (n=7)All (n=33)Median PFS (months. 95%CI)8.3 (7.2, 16.5)2.9 (1.1, NE)7.3 (5.3, 14.1)12-month PFS (95% CI)29% (14%, 59%)14% (2%, 88%)26% (13%, 50%)Median OS (months, 95% CI)22.2 (20.6, NE)2.9 (1.1, NE)20.6 (10.1, NE)12-month OS (95% CI)76% (59%, 97%)14% (2%, 88%)61% (44%, 83%) Open table in a new tab Pembrolizumab in combination with chemotherapy demonstrated a response rate of 42% and median survival of 22 months among patients with recurrent EGFR-mutated NSCLC. These results warrant further study of this combination in this patient population.

Prospective Evaluation of a Circulating Tumor Cell Sensitivity Profile to Predict Response to Cisplatin Chemotherapy in Metastatic Breast Cancer Patients.

BackgroundCisplatin (cDDP) has regained interest for metastatic breast cancer (MBC) patients, given the platinum sensitivity in subtypes and better manageable toxicity. Here, the primary aim was to determine whether molecular characteristics of circulating tumor cells (CTCs) could identify patients responding to cDDP and to describe the outcomes to cDDP monotherapy in a large group of MBC patients pretreated with anthracycline- and taxane-based treatments.MethodsBased on cell line data, a CTC-cDDP-sensitivity profile was generated. Applying an A’Herns single-stage phase II design, further investigation was considered worthwhile if 5/10 patients with a favorable profile responded to cDDP. Patients received 70mg/m2 cDDP every three weeks, CTCs were enumerated and the CTC-cDDP-sensitivity profile was determined. In total, 65 heavily pretreated MBC patients (77% received ≥2 lines of previous chemotherapy for MBC) were eligible for the per-protocol analysis. Primary endpoint was response rate, secondary endpoints included best observed response, progression-free survival (PFS) and overall survival (OS).ResultsThe best observed response during cDDP therapy was a partial response in 7% and stable disease in 56% of the patients. None of the patients with a favorable CTC-cDDP-sensitivity profile had a response. The median baseline CTC count was 8 (range 0-3254). Patients with <5 CTCs had a better PFS and OS than patients with ≥5 CTCs (median PFS 4.5 months (95%CI 2.38-6.62) vs. 2.1 months [(95%CI 1.34-2.80)(p=0.009)] and median OS 13.1 months (95%CI 9.89-16.33) vs. 5.6 months [(95%CI 3.60-7.64)(p=0.003)]. No other factors than CTC count were associated with outcome to cDDP therapy, including triple-negative breast cancer versus ER-positive tumors.ConclusionsThe CTC-cDDP-sensitivity profile was unable to select patients responding to cDDP monotherapy. In an unselected group of heavily pretreated MBC patients, cDDP yields outcomes comparable to other chemotherapeutic regimens for heavily pretreated MBC patients. CTC count was the only factor associated with outcome in these patients.Clinical Trial Registration(https://www.trialregister.nl/trial/3885, identifier NTR4046)

Quantification of BIM mRNA in circulating tumor cells of osimertinib-treated patients with EGFR mutation-positive lung cancer

The response rate for osimertinib is high among patients with untreated epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancer (NSCLC). However, there exist no biomarkers to predict the efficacy of the same. This study investigated whether BIM-γ mRNA expression in circulating tumor cells (CTCs) predicts poor outcomes for osimertinib treatment in patients with EGFR mutation-positive NSCLC. Patients with advanced EGFR-tyrosine kinase inhibitor-untreated NSCLC or post-operative recurrence with EGFR-sensitive mutations (exon 19 deletion or L858R mutation) were included. Informed consent was obtained from all participants. The candidate biomarker BIM-γ was measured in CTCs after blood collection (10mL of whole blood) at baseline. CTCs were collected with the ClearCell FX system, and quantitative real-time PCR was performed. Relative expression of BIM-γ mRNA from CTCs, as normalized to the reference gene (GAPDH mRNA), was calculated using the KCL22cell line for calibration. We enrolled 30 EGFR mutation-positive NSCLC patients treated with osimertinib during the period from April 2018 through December 2019. All the patients had an EGFR mutation at the primary site: exon 19 deletion in 15 cases and L858R in 15 cases. Median CTC count at baseline was 12 (range 3-127)/7.5mL, and median BIM-γ mRNA expression was 0.073 (range 0-1.37). Furthermore, the response rate to osimertinib was worse in patients with high than in those with low BIM-γ mRNA expression (n=15 each) (26.6% vs. 73.3%, respectively; p=0.011). Progression-free survival did not significantly differ between groups (p=0.13). BIM-γ mRNA overexpression in CTCs from EGFR mutation-positive NSCLC patients is a potential a biomarker for poor response to osimertinib. UMIN:00032055.

Abstract 5367: Identification and clinical value of the circulating tumor cells (CTCs) in the colorectal cancer

Abstract The number of circulating tumor cells (CTCs) hase been found as a promising predictive and diagnostic biomarker of colorectal cancer (CRC). The purpose of the study was to enumerate and characterize CTCs from the CRC patients and evaluate the correlation with the clinical stages.Peripheral blood from 57 CRC patients and 6 healthy donors were subjected to isolate CTC by a negative selection (EasySepTM) method. The CTCs were detected by the immunofluorescence staining with the tumor cell markers such as epithelial cell adhesion molecule (EPCAM) and cytokeratin (CK) antibodies and counted them. The extent of positive expressions of EPCAM and cytokeratin (CK) proteins were used to characterize the CTCs and the subpopulations were correlated with the tumor stages of the CRC patients. P&amp;lt;0.05 was considered as statistically significant.CTCs were detected in 72% (41/57) of the CRC patients. Comparing to the healthy donors (HD), the CTC count was higher (p=0.0062) in the CRC patients. In addition, CTC clusters were found in 32% (18/57) of patients with CRC while total CTCs were significantly higher than the cluster count (p=0.001). Among the CRC patients, CTCs were more abundant in the advanced stages compared to the early stages (p=0.0019). Moreover, we found the length of the individual CTCs were significantly larger than the CTCs in the cluster (p&amp;lt;0.0001) and significantly correlated (p=0.036) with the tumor stages. However, we identified the EPCAMPosCkPos subclones in 38 (93%) out of 41 CTC positive cases and a median of 8.0 (range: 0-60) CTCs were counted. In contrast, EPCAMPosCkNeg subpopulations were detected in 27 (66%) patients and the median CTC count was 2.0 (range: 0-18). Interestingly, EPCAMPosCkPos CTC subclones were significantly higher (p=0.011) than EPCAMPosCkNeg subclones, and the number of EPCAMPosCkPos CTCs was merely associated (p=0.0068) with the tumor stages. We conclude that the morphological and phenotypic features of the CTCs are closely relevant to the clinical stages, which could provide vital information to improve the patient stratification and treatment selection. Citation Format: Faysal-Bin Hamid, Farhad Islam, Cu-Tai Lu, Marco Matos, Tracie Cheng, Vinod Gopalan, Alfred King-yin Lam. Identification and clinical value of the circulating tumor cells (CTCs) in the colorectal 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 5367.

Microsieves for the detection of circulating tumor cells in leukapheresis product in non-small cell lung cancer patients.

BackgroundCirculating tumor cells (CTC) in non-small cell lung cancer (NSCLC) patients are a prognostic and possible therapeutic marker, but have a low frequency of appearance. Diagnostic leukapheresis (DLA) concentrates CTC and mononuclear cells from the blood. We evaluated a protocol using two VyCAP microsieves to filter DLA product of NSCLC patients and enumerate CTC, compared with CellSearch as a gold standard.MethodsDLA was performed in NSCLC patients before starting treatment. DLA product equaling 2×108 leukocytes was diluted to 9 mL with CellSearch dilution buffer in a Transfix CTC tube. Within 72 hours the sample was filtered with a 7 µm pore microsieve and subsequently over a 5µm pore microsieve. CTC were defined as nucleated cells which stained for cytokeratin, but lacked CD45 and CD16. CellSearch detected CTC in the same volume of DLA.ResultsOf 29 patients a median of 1.4 mL DLA product (range, 0.5–4.1) was filtered (2% of total product) successfully in 93% and 45% of patients using 7 and 5 µm pores, respectively. Two DLA products were unevaluable for CTC detection. Clogging of the 5 µm but not 7 µm microsieves was positively correlated with fixation time (ρ=0.51, P<0.01). VyCAP detected CTC in 44% (12/27) of DLA products. Median CTC count per mL DLA was 0 [interquartile range (IQR): 0–1]. CellSearch detected CTC in 63% of DLA products (median =0.9 CTC per mL DLA, IQR: 0–2.1). CTC counts detected by CellSearch were significantly higher compared with VyCAP (P=0.05).ConclusionsVyCAP microsieves can identify CTC in DLA product, but workflows need to be optimized.

Anesthesia and Circulating Tumor Cells in Primary Breast Cancer Patients: A Randomized Controlled Trial.

The effect of anesthetic drugs on cancer outcomes remains unclear. This trial aimed to assess postoperative circulating tumor cell counts-an independent prognostic factor for breast cancer-to determine how anesthesia may indirectly affect prognosis. It was hypothesized that patients receiving sevoflurane would have higher postoperative tumor cell counts. The parallel, randomized controlled trial was conducted in two centers in Switzerland. Patients aged 18 to 85 yr without metastases and scheduled for primary breast cancer surgery were eligible. The patients were randomly assigned to either sevoflurane or propofol anesthesia. The patients and outcome assessors were blinded. The primary outcome was circulating tumor cell counts over time, assessed at three time points postoperatively (0, 48, and 72 h) by the CellSearch assay. Secondary outcomes included maximal circulating tumor cells value, positivity (cutoff: at least 1 and at least 5 tumor cells/7.5 ml blood), and the association between natural killer cell activity and tumor cell counts. This trial was registered with ClinicalTrials.gov (NCT02005770). Between March 2014 and April 2018, 210 participants were enrolled, assigned to sevoflurane (n = 107) or propofol (n = 103) anesthesia, and eventually included in the analysis. Anesthesia type did not affect circulating tumor cell counts over time (median circulating tumor cell count [interquartile range]; for propofol: 1 [0 to 4] at 0 h, 1 [0 to 2] at 48 h, and 0 [0 to 1] at 72 h; and for sevoflurane: 1 [0 to 4] at 0 h, 0 [0 to 2] at 48 h, and 1 [0 to 2] at 72 h; rate ratio, 1.27 [95% CI, 0.95 to 1.71]; P = 0.103) or positivity. In one secondary analysis, administrating sevoflurane led to a significant increase in maximal tumor cell counts postoperatively. There was no association between natural killer cell activity and circulating tumor cell counts. In this randomized controlled trial investigating the effect of anesthesia on an independent prognostic factor for breast cancer, there was no difference between sevoflurane and propofol with respect to circulating tumor cell counts over time.

Abstract B19: The impact of circulating tumor cells on treatment response in early breast cancer patients with hormone receptor-positive and HER2 positive who underwent the neoadjuvant therapy

Abstract Introduction: Accumulating evidence has described that circulating tumor cells (CTCs) imply a poor prognosis in patients with early breast cancer. In this study, we evaluated the association between CTCs and response of neoadjuvant therapy in patients with hormone receptor (HR)-positive and HER2-positive breast cancer. Method: The HERAKLES study was a prospective single-arm, multicenter, phase II trial designed to evaluate the efficacy and safety of letrozole and trastuzumab for neoadjuvant therapy in postmenopausal patients with HR-positive and HER2-positive breast cancer (NCT02214004). All patients received trastuzumab every 3 weeks for eight cycles and daily letrozole for 24 weeks, followed by the surgery. After neoadjuvant therapy, the clinical response was assessed by the radiologic modalities. The CTCs were investigated by using a microfabricated porous filter in which the size of the square pores was optimized as 8.5 × 8.5 μm for the nickel electroformed membrane filter from 10mL of whole blood. Then, immunofluorescence staining was conducted with antibodies against CD45, EpCAM, cytokeratins, and then counterstained with DAPI. The CTCs were determined as DAPI-positive, EpCAM-positive, CK-positive, and CD45-negative cells. The CTCs analysis before and after neoadjuvant therapy was performed in 21 patients. In addition, we classified the patients into 4 groups: Group A, CTC-negative at both times (n=4); Group B, presence of CTC at pretreatment and CTC-negative at post-treatment (n=4); Group C, CTC-negative at pretreatment and presence of CTC at post-treatment (n=6); Group D, presence of CTC at both times (n=7). Results: The CTCs were detected in 11 (52.4%; median CTCs count, 2; range, 1-26) patients at pre-treatment and 13 (61.9%; median CTCs count, 4; range, 1-11) patients at post-treatment. CTC detection and CTC changes after neoadjuvant therapy were not associated with primary tumor characteristics. There was no patient with disease progression after neoadjuvant therapy in group A and B. However, the disease progression was observed in one (16.7%) patient in group C and two (28.6%) patients in group D (p=0.470). When the CTC was analyzed as continuous value, the CTCs were increased in all (the average change of CTCs, +6.0) patients with disease progression after neoadjuvant therapy, although the CTCs were increased in 7 (38.9%; the average change of CTCs, -1.3) of 18 patients without progression disease (p=0.09). Conclusions: The increase in CTCs after neoadjuvant treatment, including aromatase inhibitor and trastuzumab, tended to be correlated with poor treatment response in HR+/HER2+ breast cancer patients, although it remains underpowered. Our results supported that the monitoring of CTCs may reflect the response to neoadjuvant aromatase inhibitor and trastuzumab therapy in HR+/HER2+ breast cancer. Citation Format: Soong June Bae, Soeun Park, Chi Hwan Cha, Dooreh Kim, Janghee Lee, Sung Gwe Ahn, Joon Jeong. The impact of circulating tumor cells on treatment response in early breast cancer patients with hormone receptor-positive and HER2 positive who underwent the neoadjuvant therapy [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 B19.

Clinical significance of circulating tumor cells in patients with locally advanced head and neck squamous cell carcinoma.

The present study aimed to investigate the clinical relevance of circulating tumor cells (CTCs) in patients with locally advanced head and neck squamous cell carcinoma (LA-HNSCC), particularly in patients with nasopharyngeal and hypopharyngeal squamous cell carcinoma. CTCs were isolated using negative immunomagnetic bead enrichment and were identified by fluorescence in situ hybridization. Youden's index and the receiver operating characteristic (ROC) curve were used to select the optimal CTC baseline value. χ2 test or Fisher's test were used to determine the association between CTC counts and clinical parameters, curative effects and prognosis. The Kaplan-Meier estimator was used to analyze overall survival (OS) and progression-free survival (PFS). In the present study, 356 peripheral blood samples (178 pretreatment samples and 178 post-treatment samples) from 178 patients were examined. The results revealed that the pretreatment CTC detection rate was 73.8%. The minimum, maximum and median CTC counts were 1, 22 and 2/3.2 ml, respectively. The number of polyploid CTCs was associated with distant metastasis (P=0.026). In addition, patients with undetectable CTCs, and decreasing or negative CTCs post-treatment tended to have a good prognosis (P<0.05). For nasopharyngeal squamous cell carcinoma, the PFS of patients with increased CTCs and CTCs ≥2/3.2 ml after treatment was significantly lower (P<0.05). For hypopharyngeal squamous cell carcinoma, it was suggested that CTCs with a cutoff value of 3 may be used to evaluate PFS and OS before and after treatment. In conclusion, CTCs may be used to monitor disease progression and the response to chemoradiotherapy for patients with LA-HNSCC. Furthermore, CTCs are a better predictor of the prognosis of hypopharyngeal squamous cell carcinoma than that of nasopharyngeal squamous cell carcinoma.

Abstract P4-01-04: The distribution and prognostic significance of circulating tumor cells are different in invasive lobular carcinoma compared to invasive ductal carcinoma of the breast

Abstract Background: Circulating tumor cells (CTCs) have repeatedly been shown to carry independent prognostic information in metastatic breast cancer (MBC). A CTC count of 5 cells per 7.5 mL blood is a generally accepted cut-off, where MBCs with &amp;lt;5 CTCs are classified as MBCindolent and ≥5 CTCs as MBCaggressive. Furthermore, several studies have shown that the presence of CTC clusters add prognostic information to CTC count alone. Invasive lobular carcinoma (ILC) is the second most common histological breast cancer (BC) type (~10%). The vast majority of all BCs (~80%) are classified as invasive ductal carcinoma (IDC). Many distinguishing clinicopathological and genomic features have been identified between these two types, but in spite of this, current clinical management strategies and treatments are similar and mainly based on studies dominated by IDCs. The aim of this study was to explore potential differences in the distribution and prognostic significance of CTC count and CTC clusters in metastatic ILC vs. IDC, in a prospective observational study. Patients and methods: Between April 2011 and June 2016, 139 women with newly diagnosed metastatic ILC (N=28) and IDC (N=111) were included. CTCs and CTC clusters were detected, using CellSearch technology (Menarini Silicon Biosystems), at baseline (BL) before first-line systemic therapy, and during the first 6 months of follow-up (FU). The primary endpoint was progression-free survival (PFS) and the secondary endpoint overall survival (OS). Median FU time was 49 (27-93) months. Results: There was a highly significant (P&amp;lt;0.001) difference in the median CTC count between ILC (70, range 0-2598) and IDC (2, range 0-668) at BL, and presence of CTC clusters was also higher (36% vs. 18%, P=0.07). These differences between ILC and IDC persisted in the luminal A-like subgroup. The CTC count and CTC clusters declined in both ILC (median count 4, range 0-85; clusters: 4%) and IDC (median count 0, range 0-263; clusters: 12%) after 1 month of systemic treatment, but the decline was most pronounced in ILC. Seventy-nine percent of the ILCs and 46% of the IDCs were classified as MBCaggressive (CTC ≥5) at BL (P=0.003). The prognostic value of CTC ≥5 on PFS (HR 1.5, 95% CI 0.55-4.0, P=0.44) and OS (HR 2.4, 95% CI 0.71-8.3, P=0.16) in ILC was weak, whereas significant prognostic effects were seen in IDC (PFS: HR 1.7, 95% CI 1.2-2.6, P=0.007; OS: HR 2.1, 95% CI 1.3-3.3, P=0.002). With higher cut-offs the prognostic impact of CTC count on PFS/OS was significant also in ILC (CTC ≥20: HR 3.0, 95% CI 1.3-6.8, P=0.01 / HR 3.1, 95% CI 1.2-8.3, P=0.02) (CTC ≥80: HR 3.6, 95% CI 1.5-8.8, P=0.004 / HR 5.9, 95% CI 2.0-17.8, P=0.002) and the prognostic effect in IDC remained. The presence of ≥1 CTC cluster was a negative prognostic factor significantly associated with impaired survival in ILC (PFS: HR 4.6, 95% CI 1.7-12.4, P=0.003; OS: HR 4.9, 95% CI 1.7-13.8, P=0.003), whereas the effect was weaker in IDC (PFS: HR 1.2, 95% CI 0.69-2.0, P=0.55; OS: HR 1.9, 95% CI 1.1-3.3, P=0.02). First-line systemic treatment was similar in ILC vs. IDC (endocrine 46% vs. 39% and chemotherapy 54% vs. 61%) and the overall prognosis did not differ (PFS: HR 0.89, 95% CI 0.57-1.4, P=0.59; OS: HR 0.99, 95% CI 0.60-1.6, P=0.96). Conclusions: In this study of metastatic ILC and IDC, the CTC count at BL was remarkably higher in ILCs and the presence of CTC clusters was also more common, in spite of the fact that no difference in prognosis was seen. The prognostic value of the generally accepted CTC cut-off (≥5) was clearly weaker and the presence of CTC clusters stronger in ILC vs. IDC. A higher cut-off might be more suitable in ILCs in order to better discriminate between MBCindolent and MBCaggressive forms, and CTC clusters could potentially add prognostic information. Citation Format: Ulrik Christoffer Narbe, Pär-Ola Bendahl, Kristina Aaltonen, Mårten Fernö, Carina Forsare, Charlotte Levin Tykjær Jørgensen, Anna-Maria Larsson, Lisa Rydén. The distribution and prognostic significance of circulating tumor cells are different in invasive lobular carcinoma compared to invasive ductal carcinoma of the breast [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-01-04.