Eleni Politaki

Epithelial to mesenchymal transition markers expressed in circulating tumour cells of early and metastatic breast cancer patients

IntroductionEpithelial to mesenchymal transition (EMT) is considered an essential process in the metastatic cascade. EMT is characterised by upregulation of vimentin, Twist, Snail, Slug and Sip1 among others. Metastasis is also associated with the presence of circulating tumour cells (CTCs) and disseminated tumour cells in the blood and bone marrow, respectively, of breast cancer patients, but the expression of EMT markers in these cells has not been reported so far.MethodsThe expression of Twist and vimentin in CTCs of 25 metastatic and 25 early breast cancer patients was investigated by using double-immunofluorescence experiments in isolated peripheral blood mononuclear cell cytospins using anti-cytokeratin (anti-CK) anti-mouse (A45-B/B3) and anti-Twist or anti-vimentin anti-rabbit antibodies.ResultsAmong early breast cancer patients, vimentin-and Twist-expressing CK+ CTCs were identified in 77% and 73% of the patients, respectively, and in 100% of the patients with metastatic breast cancer for both markers (P = 0.004 and P = 0.037, respectively). Among patients with early disease, 56% and 53% of the CK+ CTCs were double-stained with vimentin and Twist, and the corresponding values for metastatic patients were 74% and 97%, respectively (P = 0.005 and P = 0.0001, respectively). The median expression of CK+vimentin+ and CK+Twist+ cells per patient in metastatic patients was 98% and 100%, and in an adjuvant chemotherapy setting the corresponding numbers were 56% and 40.6%, respectively. Triple-staining experiments revealed that all CK+Twist+ or CK+vimentin+ cells were also CD45-, confirming their epithelial origin. Immunomagnetic separation of CTCs and triple-immunofluorescence with anti-CK/anti-Twist/anti-vimentin antibodies demonstrated that both mesenchymal markers could be coexpressed in the same CK+ cell, since 64% of the total identified CTCs were triple-stained. There was a significant correlation (P = 0.005) between the number of CTCs expressing Twist and vimentin within the same setting.ConclusionsCTCs expressing Twist and vimentin, suggestive of EMT, are identified in patients with breast cancer. The high incidence of these cells in patients with metastatic disease compared to early stage breast cancer strongly supports the notion that EMT is involved in the metastatic potential of CTCs.

Different Prognostic Value of Cytokeratin-19 mRNA Positive Circulating Tumor Cells According to Estrogen Receptor and HER2 Status in Early-Stage Breast Cancer

PURPOSE To examine the prognostic value of cytokeratin-19 (CK-19) mRNA-positive circulating tumor cells (CTCs) in early-stage breast cancer patients focusing on clinically relevant subgroups based on estrogen receptor (ER) and HER2 expression. PATIENTS AND METHODS CK-19 mRNA-positive CTCs were detected by real-time reverse transcriptase polymerase chain reaction in the blood of 444 consecutive, stage I-III, breast cancer patients before initiation of adjuvant chemotherapy. The association between detection of CK-19 mRNA-positive CTCs and clinical outcome was analyzed for patients with ER-positive, ER-negative, triple-negative, HER2-positive, and ER-positive/HER2-negative tumors. RESULTS CK-19 mRNA-positive CTCs were detected in 181 (40.8%) of 444 patients; 109 (41.9%) of 260 patients with ER-positive tumors; 71 (40.6%) of 175 patients with ER-negative tumors; 27 (35%) of 77 patients with triple-negative tumors; 35 (39.8%) of 88 patients with HER2-positive tumors; and 82 (44.1%) of 186 patients with ER-positive/HER2-negative tumors. After a median follow-up of 53.5 months, patients with CK-19 mRNA-positive CTCs experienced reduced disease-free survival (DFS; P < .001) and overall survival (OS; P < .001); this was mainly observed in patients with ER-negative (P < .001 and P < .001, respectively) but not ER-positive tumors (P = .172 and P = .425, respectively) and in patients with triple-negative (P = .008 and P = .001, respectively) and HER2-positive (P = .023 and P = .040, respectively) but not ER-positive/HER2-negative tumors (P = .210 and P = .578, respectively). In multivariate analysis, the interaction between CK-19 mRNA-positive CTCs and ER status was the strongest independent prognostic factor for reduced DFS (hazard ratio [HR], 3.808; 95% CI, 2.415 to 6.003; P < .001) and OS (HR, 4.172; 95% CI, 2.477 to 9.161; P < .001). CONCLUSION Detection of CK-19 mRNA-positive CTCs before adjuvant chemotherapy predicts poor clinical outcome mainly in patients with ER-negative, triple-negative, and HER2-positive early-stage breast cancer.

Gene expression profile of circulating tumor cells in breast cancer by RT-qPCR

BackgroundCirculating tumor cells (CTCs) have been associated with prognosis especially in breast cancer and have been proposed as a liquid biopsy for repeated follow up examinations. Molecular characterization of CTCs is difficult to address since they are very rare and the amount of available sample is very limited.MethodsWe quantified by RT-qPCR CK-19, MAGE-A3, HER-2, TWIST1, hTERT α+β+, and mammaglobin gene transcripts in immunomagnetically positively selected CTCs from 92 breast cancer patients, and 28 healthy individuals. We also compared our results with the CellSearch system in 33 of these patients with early breast cancer.ResultsRT-qPCR is highly sensitive and specific and can detect the expression of each individual gene at the one cell level. None of the genes tested was detected in the group of healthy donors. In 66 operable breast cancer patients, CK-19 was detected in 42.4%, HER-2 in 13.6%, MAGE-A3 in 21.2%, hMAM in 13.6%, TWIST-1 in 42.4%, and hTERT α+β+ in 10.2%. In 26 patients with verified metastasis, CK-19 was detected in 53.8%, HER-2 in 19.2%, MAGE-A3 in 15.4%, hMAM in 30.8%, TWIST-1 in 38.5% and hTERT α+β+in 19.2%. Our preliminary data on the comparison between RT-qPCR and CellSearch in 33 early breast cancer patients showed that RT-qPCR gives more positive results in respect to CellSearch.ConclusionsMolecular characterization of CTCs has revealed a remarkable heterogeneity of gene expression between breast cancer patients. In a small percentage of patients, CTCs were positive for all six genes tested, while in some patients only one of these genes was expressed. The clinical significance of these findings in early breast cancer remains to be elucidated when the clinical outcome for these patients is known.

Molecular Detection and Prognostic Value of Circulating Cytokeratin-19 Messenger RNA–Positive and HER2 Messenger RNA–Positive Cells in the Peripheral Blood of Women with Early-Stage Breast Cancer

PURPOSE The aim of this study was to evaluate the clinical relevance of the simultaneous detection of cytokeratin (CK)-19 messenger RNA (mRNA)- and HER2 mRNA-positive cells in peripheral blood of women with early-stage breast cancer. PATIENTS AND METHODS CK-19 mRNA- and HER2 mRNA-positive cells were detected using a real-time and a nested reverse-transcriptase polymerase chain reaction assay, respectively, in a cohort of 185 women with early-stage breast cancer before the initiation of any adjuvant systemic treatment. Detection of CK-19 mRNA- and HER2 mRNA-positive cells in the peripheral blood was correlated with clinical outcome. RESULTS Overall, 63 of the 185 patients (34%) had detectable CK-19 mRNA-positive cells, and 33 (52.3%) also had detectable HER2 mRNA-positive cells. Patients with CK-19/HER2 mRNA-negative cells showed a trend toward longer disease-free survival (DFS) compared with patients with CK-19 mRNA-positive/HER2 mRNA-negative cells (P = .054) and had longer DFS than patients with CK-19/HER2 mRNA-positive cells (P < .001). Similarly, overall survival (OS) was higher in patients with CK-19/HER2 mRNA-negative cells compared with patients with CK-19 mRNA-positive/HER2 mRNA-negative cells (P = .039) or CK-19/HER2 mRNA-positive cells (P < .001). Patients with CK-19/HER2 mRNA-positive cells had shorter DFS but not OS compared with patients with CK-19 mRNA-positive/HER2 mRNA-negative cells. In multivariate analysis, the simultaneous detection of CK-19 mRNA- and HER2 mRNA-positive cells was independently associated with early relapse. CONCLUSION The simultaneous detection of CK-19 mRNA- and HER2 mRNA-positive cells in peripheral blood predicts poor clinical outcome for women with early-stage breast cancer.

Variable expression levels of keratin and vimentin reveal differential EMT status of circulating tumor cells and correlation with clinical characteristics and outcome of patients with metastatic breast cancer

BackgroundCTCs expressing variable levels of epithelial and mesenchymal markers in breast cancer have previously been reported. However, no information exists for keratin expression levels of CTCs in association with disease status, whereas assays for the characterization of transitional EMT phenotypes of CTCs in breast cancer are rather lacking. We investigated the correlation between keratin expression of CTCs and patients’ outcome and characterized the EMT status of CTCs via the establishment of a numerical “ratio” value of keratin and vimentin expression levels on a single cell basis.MethodsKeratin expression was evaluated in 1262 CTCs from 61 CTC-positive patients with metastatic breast cancer, using analysis of images obtained through the CellSearch System. For the determination of vimentin/keratin (vim/K) ratios, expression levels of keratin and vimentin were measured in cytospin preparations of luminal (MCF-7 and T47D) and basal (MDA.MB231 and Hs578T) breast cancer cell lines and 110 CTCs from 5 CTC-positive patients using triple immunofluorescence laser scanning microscopy and image analysis.ResultsMCF-7 and T47D displayed lower vim/K ratios compared to MDA.MB231 and Hs578T cells, while MCF-7 cells that had experimentally undergone EMT were characterized by varying intermediate vim/K ratios. CTCs were consisted of an heterogeneous population presenting variable vim/K values with 46% of them being in the range of luminal breast cancer cell lines. Keratin expression levels of CTCs detected by the CellSearch System correlated with triple negative (p = 0.039) and ER-negative (p = 0.025) breast cancer, and overall survival (p = 0.038).ConclusionsKeratin expression levels of CTCs correlate with tumor characteristics and clinical outcome. Moreover, CTCs display significant heterogeneity in terms of the degree of EMT phenotype that probably reflects differential invasive potential. The assessment of the vim/K ratios as a surrogate marker for the EMT status of CTCs merits further investigation as a prognostic tool in breast cancer.

International study on inter-reader variability for circulating tumor cells in breast cancer

IntroductionCirculating tumor cells (CTCs) have been studied in breast cancer with the CellSearch® system. Given the low CTC counts in non-metastatic breast cancer, it is important to evaluate the inter-reader agreement.MethodsCellSearch® images (N = 272) of either CTCs or white blood cells or artifacts from 109 non-metastatic (M0) and 22 metastatic (M1) breast cancer patients from reported studies were sent to 22 readers from 15 academic laboratories and 8 readers from two Veridex laboratories. Each image was scored as No CTC vs CTC HER2- vs CTC HER2+. The 8 Veridex readers were summarized to a Veridex Consensus (VC) to compare each academic reader using % agreement and kappa (κ) statistics. Agreement was compared according to disease stage and CTC counts using the Wilcoxon signed rank test.ResultsFor CTC definition (No CTC vs CTC), the median agreement between academic readers and VC was 92% (range 69 to 97%) with a median κ of 0.83 (range 0.37 to 0.93). Lower agreement was observed in images from M0 (median 91%, range 70 to 96%) compared to M1 (median 98%, range 64 to 100%) patients (P < 0.001) and from M0 and <3CTCs (median 87%, range 66 to 95%) compared to M0 and ≥3CTCs samples (median 95%, range 77 to 99%), (P < 0.001). For CTC HER2 expression (HER2- vs HER2+), the median agreement was 87% (range 51 to 95%) with a median κ of 0.74 (range 0.25 to 0.90).ConclusionsThe inter-reader agreement for CTC definition was high. Reduced agreement was observed in M0 patients with low CTC counts. Continuous training and independent image review are required.

Evaluation of Isolation Methods for Circulating Tumor Cells (CTCs).

Background: Detection of CTCs is a poor prognostic factor for many cancer types; however, their very low frequency represents an obstacle for their detection. The objective of the current study was to compare the performance of commonly used methods for CTCs isolation. Methods: The evaluated methods using spiking experiments of MCF7, SKBR3 and MDA MB-231 breast cancer cell lines were (i) ficoll density gradient separation (DGS), (ii) red blood cell lysis (Erythrolysis) isolation, (iii) positive immunomagnetic selection (EpCAM Dynal beads), (iv) two different negative immunomagnetic separation systems (Dynal vs Miltenyi CD45 beads) as well as (v) the Cell Search platform and (vi) the ISET system. Results: The recovery rates of Erythrolysis and DGS were 39% and 24%, respectively. Magnetic isolations are ranked from the worse to the best recovery rate as follows:, Myltenyi-anti-CD45 microbeads (24%); Dynal-anti-EpCAM beads (75%); Dynabeads-anti-CD45 (97%). CTCs isolation from blood samples using the CellSearch and ISET systems revealed that the recovery rate for Cell Search and ISET was 52% and 95%, respectively. Conclusions: Dynal-anti-CD45 beads have the best recovery rate compared to other magnetic methods. Furthermore the recovery rate of ISET was higher compared to Cell Search, especially for the more aggressive MDA-MB 231 cell line.

Heterogeneity of circulating tumor cells (CTCs) in patients with recurrent small cell lung cancer (SCLC) treated with pazopanib

OBJECTIVES To investigate the effect of pazopanib on different CTCs subpopulations in patients with recurrent SCLC and evaluate their clinical relevance. METHODS Peripheral blood was obtained before the administration of pazopanib (n=56 patients), after the first cycle (n=35 patients) and at disease progression (n=45 patients). CTCs were detected by CellSearch and double immunofluorescent staining using antibodies against the cytokeratins (CK), TTF-1, CD56 and VEGFR2. RESULTS Before treatment, CTCs could be detected in 50% of patients by CellSearch; phenotypic characterization of CTCs demonstrated that 50%, 46.6% and 27.6% of patients had CD45-/TTF1+, CD45-/CD56+ and TTF-1+/CD56+ CTCs, respectively. Additionally, 59% of CTCs were TTF-1+/VEGFR2+ and 53% CK+/VEGFR2+. One pazopanib cycle resulted to a significant decrease of the number of CTCs (CellSearch: p=0.043) and CK+/VEGFR2+ cells (p=0.027). At the time of PD, both the total number of CTCs (p=0.027) and the number of the different subpopulations were significantly increased compared to post-1st cycle values; this increased CTCs number was associated with a significant increase of TTF-1+/VEGFR2+ (p=0.028) and CK+/VEGFR2+ CTCs (p=0.018). In multivariate analysis, only the number of CTCs as assessed by CellSearch after one treatment cycle was significantly associated with OS (HR: 0.21; p=0.005). CONCLUSIONS Pazopanib has a significant effect on different subpopulations of CTCs in patients with relapsed SCLC; the detection of VEGFR2+ CTCs during treatment could be a surrogate marker associated with resistance to pazopanib.

ESR1 methylation: a liquid biopsy-based epigenetic assay for the follow up of patients with metastatic breast cancer receiving endocrine treatment

Purpose: Liquid biopsy provides real-time monitoring of tumor evolution and response to therapy through analysis of circulating tumor cells (CTCs) and plasma-circulating tumor DNA (ctDNA). ESR1 epigenetic silencing potentially affects response to endocrine treatment. We evaluated ESR1 methylation in CTCs and paired plasma ctDNA. We evaluated ESR1 methylation in CTCs and paired plasma ctDNA as a potential biomarker for response to everolimus/exemestane treatment. Experimental Design: A highly sensitive and specific real-time MSP assay for ESR1 methylation was developed and validated in (i) 65 primary breast tumors formalin-fixed paraffin-embedded (FFPE), (ii) EpCAM+ CTC fractions (122 patients and 30 healthy donors; HD), (iii) plasma ctDNA (108 patients and 30HD), and (iv) in CTCs (CellSearch) and in paired plasma ctDNA for 58 patients with breast cancer. ESR1 methylation status was investigated in CTCs isolated from serial peripheral blood samples of 19 patients with ER+/HER2− advanced breast cancer receiving everolimus/exemestane. Results: ESR1 methylation was detected in: (i) 25/65 (38.5%) FFPEs, (ii) EpCAM+ CTC fractions: 26/112 (23.3%) patients and 1/30 (3.3%) HD, and (iii) plasma ctDNA: 8/108 (7.4%) patients and 1/30 (3.3%) HD. ESR1 methylation was highly concordant in 58 paired DNA samples, isolated from CTCs (CellSearch) and corresponding plasma. In serial peripheral blood samples of patients treated with everolimus/exemestane, ESR1 methylation was observed in 10/36 (27.8%) CTC-positive samples, and was associated with lack of response to treatment (P = 0.023, Fisher exact test). Conclusions: We report for the first time the detection of ESR1 methylation in CTCs and a high concordance with paired plasma ctDNA. ESR1 methylation in CTCs was associated with lack of response to everolimus/exemestane regimen. ESR1 methylation should be further evaluated as a potential liquid biopsy-based biomarker. Clin Cancer Res; 24(6); 1500–10. ©2017 AACR.

TTF-1- and/or CD56-positive Circulating Tumor Cells in patients with small cell lung cancer (SCLC)

The aim of the study was to evaluate the phenotypic CTCs heterogeneity (TTF-1+ and/or CD56+) in SCLC patients and correlate it with the CellSearch. Peripheral blood was obtained from 108 consecutive patients. CTCs were detected by CellSearch and double-immunofluorescence using anti-CD45, anti-TTF-1 and anti-CD56 antibodies. Before chemotherapy TTF-1+/CD45−, CD56+/CD45− and TTF-1+/CD56+ CTCs were detected in 66(61.1%), 55(50.9%) and 46(42.6%) patients, respectively; 60.2% of patients were CellSearch+. Among the 22 patients with 0 CTCs/7.5 ml on CellSearch, TTF-1+/CD45−, CD56+/CD45− and TTF-1+/CD56+ CTCs were detected in 8(36.4%), 6(27.3) and 6(27.3%) patients, respectively; no CK+/EpCAM+ or TTF1+/EpCAM+ CTCs were detected in these patients. One-chemotherapy cycle decreased both the number of positive patients (p < 0.001) and their CTC number (p < 0.001), irrespectively of their phenotype and the detection method. The incidence and number of the different CTC subpopulations on PD, was significantly increased at their baseline levels. Multivariate analysis revealed that the increased number of CTCs at baseline and on PD were significantly associated with decreased PFS (p = 0.048) and OS (p = 0.041), respectively. There is an important CTC heterogeneity in such patients according to the expression of TTF-1 and CD56 which could detect EpCAM− CTC subpopulations and, thus, undetectable by CellSearch. These CTC subpopulations are dynamically correlated with treatment efficacy and disease-progression.