Abstract 1966: Dr

Background: According to recent publications of our group, JUNB and CXCR4 were overexpressed in CTCs and DTCs isolated from breast cancer patients. This expression was related with patients’ clinical outcome. Current study investigates for the first time, the expression of JUNB and CXCR4 in CTCs from patients with Non-Small Cell Lung cancer (NSCLC) and Small Cell Lung Cancer (SCLC).

Methods: Forty four patients were enrolled in this study (30 NSCLC and 14 SCLC patients, before the initiation of 1st line treatment). ISET system was used for NSCLC patients' samples preparation, while the CTCs from SCLC patients were isolated using Ficoll density gradient. Triple immunofluorescence experiments were performed, using CK, JUNB, and CXCR4 antibodies. Results conducted using confocal laser scanning microscopy for NSCLC samples and the VyCAP system for SCLC samples.

Results: Sixteen out of 30 NSCLC patients (53.33%), were positive for CTCs, while all SCLC patients harbored CK-positive cells. Most common phenotypes in CK-positive NSCLC patients were the [(CK+/JUNB+/CXCR4+): 50% (8/16patients)], [(CK+/JUNB+/CXCR4-): 43.75%, (7/16)] and the [(CK+/JUNB-/CXCR4-): 37.5% (6/16)]. Less frequent phenotype was the [(CK+/JUNB-/CXCR4+): 6.25%, (1/16)]. Analysis of the mean isolated CTCs/patient revealed that most of the isolated CTCs belonged to the (CK+/JUNB+/CXCR4+) phenotype (42.19%), while less frequent were the (CK+/JUNB+/CXCR4-): 33.13%, (CK+/JUNB-/CXCR4-): 18.44% and the (CK+/JUNB-/CXCR4+): 6.25% phenotypes. Survival analysis revealed that the presence of (CK+/JUNB+/CXCR4+) was related to poorer OS (cox regression: p=0.008) and PFS (Log Rank, p=0.014) All SCLC patients had detectable CTCs in their blood with 13 out of 14 of them having the (CK+/JUNB-/CXCR4-) phenotype (92.86%). The rest of CTC’s phenotypes (CK+/JUNB+/CXCR4+), (CK+/JUNB+/CXCR4-) and (CK+/JUNB-/CXCR4+) where found in 10 out of 14 patients (71.43%) each. Examination of the mean percentage of the total isolated CTCs/patient indicated that the (CK+/JUNB-/CXCR4-) phenotype was the most frequent (49.71%), while the percentages for the rest phenotypes were [(CK+/JUNB+/CXCR4-): 25.94%], [(CK+/JUNB-/CXCR4+): 12.65%] and (CK+/JUNB+/CXCR4+): 11.70%].

Conclusion: JUNB and CXCR4 were upregulated in CTCs from NSCLC and SCLC patients. However, in NSCLC the most frequent phenotype (CK+/JUNB+/CXCR4+) was also related to patients’ outcome, underlying the key role of these molecules in metastatic dissemination. Further examination will determine the role of this expression in all lung cancer subtypes. Acknowledge: This research has been co-financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH - CREATE - INNOVATE (project code: T2ΕΔΚ-01562).

Citation Format: Argyro Roumeliotou, Evangelia Pantazaka, Anastasia Xagara, Thomas Makatsoris, Angelos Koutras, Vassilis Georgoulias, Athanasios Kotsakis, Galaktia Kallergi. Dr [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1966.

Evaluation of Monocarboxylate Transporter 4 (MCT4) Expression and Its Prognostic Significance in Circulating Tumor Cells From Patients With Early Stage Non-Small-Cell Lung Cancer

Purpose: Monocarboxylate transporter 4 (MCT4) can influence the amount of lactate in the tumor microenvironment and further control cancer cell proliferation, migration, and angiogenesis. We investigated for the first time the expression of MCT4 in circulating tumor cells (CTCs) derived from early stage Non-Small Cell Lung Cancer patients (NSCLC) and whether this is associated with clinical outcome.

Experimental Design: A highly sensitive RT-qPCR assay for quantification of MCT4 transcripts was developed and validated and applied to study MCT4 expression in CTC isolated through the Parsortix size-dependent microfluidic device from 53 and 9 peripheral blood (PB) samples of NSCLC patients at baseline (pre-surgery) and at relapse, respectively, as well as the “background noise” was evaluated using peripheral blood samples from 10 healthy donors (HD) in exactly the same way as patients.

Results:MCT4 was differentially expressed between HD and NSCLC patients. Overexpression of MCT4 was detected in 14/53 (26.4%) and 3/9 (33.3%) patients at baseline and at progression disease (PD), respectively. The expression levels of MCT4 was found to increase in CTCs at the time of relapse. Kaplan-Meier analysis showed that the overexpression of MCT4 was significantly (P = 0.045) associated with progression-free survival (median: 12.5 months, range 5–31 months).

Conclusion:MCT4 overexpression was observed at a high frequency in CTCs from early NSCLC patients supporting its role in metastatic process. MCT4 investigated as clinically relevant tumor biomarker characterizing tumor aggressiveness and its potential value as target for cancer therapy. We are totally convinced that MCT4 overexpression in CTCs merits further evaluation as a non-invasive circulating tumor biomarker in a large and well-defined cohort of patients with NSCLC.

Evaluation of α-tubulin, detyrosinated α-tubulin, and vimentin in CTCs: identification of the interaction between CTCs and blood cells through cytoskeletal elements

Background

Circulating tumor cells (CTCs) are the major players in the metastatic process. A potential mechanism of cell migration and invasion is the formation of microtentacles in tumor cells. These structures are supported by α-tubulin (TUB), detyrosinated α-tubulin (GLU), and vimentin (VIM). In the current study, we evaluated the expression of those cytoskeletal proteins in CTCs.

Methods

Forty patients with breast cancer (BC) (16 early and 24 metastatic) were enrolled in the study. CTCs were isolated using the ISET platform and stained with the following combinations of antibodies: pancytokeratin (CK)/VIM/TUB and CK/VIM/GLU. Samples were analyzed with the ARIOL platform and confocal laser scanning microscopy.

Results

Fluorescence quantification revealed that the ratios CK/TUB, CK/VIM, and CK/GLU were statistically increased in MCF7 compared with more aggressive cell lines (SKBR3 and MDA-MB-231). In addition, all of these ratios were statistically increased in MCF7 cells compared with metastatic BC patients’ CTCs (p = 0.0001, p = 0.0001, and p = 0.003, respectively). Interestingly, intercellular connections among CTCs and between CTCs and blood cells through cytoskeleton bridges were revealed, whereas microtentacles were increased in patients with CTC clusters. These intercellular connections were supported by TUB, VIM, and GLU. Quantification of the examined molecules revealed that the median intensity of TUB, GLU, and VIM was significantly increased in patients with metastatic BC compared with those with early disease (TUB, 62.27 vs 11.5, p = 0.0001; GLU, 6.99 vs 5.29, p = 0.029; and VIM, 8.24 vs 5.38, p = 0.0001, respectively).

Conclusions

CTCs from patients with BC aggregate to each other and to blood cells through cytoskeletal protrusions, supported by VIM, TUB, and GLU. Quantification of these molecules could potentially identify CTCs related to more aggressive disease.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0993-z) contains supplementary material, which is available to authorized users.

Abstract P2-02-03: HER2 expression on circulating tumor cells before adjuvant chemotherapy and during follow-up in patients with HER2-negative early breast cancer

Background: Detection of circulating tumor cells (CTCs) before adjuvant chemotherapy as well as during follow-up is related to poor prognosis in early breast cancer. The presence of HER2-positive CTCs has been also associated with significantly decreased disease-free and overall survival. We hereby assessed the HER2 status of CTCs in HER2-negative patients with early breast cancer, before the initiation of adjuvant chemotherapy and during follow-up. Methods: Double staining immunofluorescent experiments using pancytokeratin (A45-B/B3) and HER2 antibodies were performed in peripheral blood mononuclear cells (PBMCs) of patients. Patients were evaluated before adjuvant therapy (n=103) and during follow-up (n=290) at intervals ranging from 6 months to 20 years post-chemotherapy. Results: CTCs were detected in 28 (27.2%) out of 103 patients pre-chemotherapy and in 94 (32.4%) out of 290 during follow-up. The mean CTC count detected at ≤2 years of follow-up was not significantly different compared to baseline [3.4 CTCs (range 1-13) vs 2.9 (range 1-12), respectively]. However, this value showed a significant decrease from 2-5 to ≥10 years of follow-up (4.2, range 1-11 vs. 1.8, range 1-4). Among CTC-positive patients, CTCs expressing HER2 were detected in 21 (75%) and in 73 (77.7%) patients pre-chemotherapy and during follow-up, respectively. The mean proportion of HER2-positive CTCs per patient was 73.5% pre-chemotherapy and 67% at follow-up. This proportion showed a significant increase at follow-up time points ≤2, 2-5 and 5-10 years [52% (p=0.0027), 65.6% (p=0.0476) and 69% (p=0.0440), respectively] compared to ≥10 years (89.2%). Conclusions: These data demonstrate that CTCs persist during follow-up in a significant percentage of early breast cancer patients. Similarly, HER2 positive CTCs are detected in a significant proportion of patients both at baseline and during follow-up. Mean CTC count appears to decrease after 10 years, whereas the population of HER2 positive CTCs seems to increase during follow-up. These results suggest that targeting HER2-positive CTCs may have implications for the prevention of late relapses.

Citation Format: Markomanolaki H, Mavroudis D, Kallergi G, Vetsika E-K, Stratigos M, Makrigiannaki K, Georgoulias V, Agelaki S. HER2 expression on circulating tumor cells before adjuvant chemotherapy and during follow-up in patients with HER2-negative early breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-03.

Abstract 1592: CXCR4 pathways in CTCs: from bioinformatics to immunophenotype

Introduction: Bioinformatics’ analysis regarding gene expression in Normal tissue vs cancer tissue, Normal blood vs cancer patients’ blood and Normal blood vs cancer tissue revealed a subgroup of 24 genes which potentially could be overexpressed in CTCs. Among these genes are: CXCR4, a chemokine receptor which is involved in tumor metastasis and, JUNB a transcription factor participating in CXCR4 pathway. The objective of this study was to confirm the results of bioinformatics’ analysis in samples from breast cancer patients and therefore to evaluate the expression of CXCR4 and JUNB in CTCs.

Methods: Triple staining immunofluoresence with panytokeratin/CXCR4/JUNB antibodies were performed in SKBR3, MDA-MB231, MCF7 and Hela cell lines. The same experiments were performed in PBMCs from normal (n = 10.) subjects and in PBMCs (n = 55) from untreated metastatic breast cancer patients.

Results: Since CXCR4, as a chemokine receptor is also expressed on hematopoietic cells, its expression on CTCs was quantified using the ARIOL system. We used cell lines and both normal vs patients’ PBMCs in order to establish an expression pattern of both molecules. Quantification experiments among cell lines revealed that CXCR4 was overexpressed in SKBR3 following the subsequent hierarchy SKBR3>MCF7>MDA-MB231>Hela. Accordingly, the expression pattern of JUNB in cell lines was SKBR3>Hela>MCF7>MDA-MB231 with higher expression in SKBR3 and lower in MDA-MB 231. Statistical analysis revealed significant differences in the expression of both molecules between healthy donors’ PBMCs and patient's PBMCs.

Subsequently, CTCs were detected in 17 out of 55 screened patients (31%). Mean intensity of CTCs for CXCR4 was 34.38 and it was higher than Hela and lower than SKBR3. Patients with CXCR4-positive CTCs (with mean expression higher than 95% of normal PBMCs) were 53%. In addition 84% of the examined CTCs had expression profile higher than normal PBMCs.

JUNB expression in CTCs (above 95% of normal PBMCs) was identified in 76.92% of patients. JUNB mean expression in CTCs was 26.1 and it was lower than SKBR3 and higher than MCF7. Furthermore 64.3% of the total CTCs have expression higher than Normal PBMCs.

Conclusion: CXCR4 and JUNB are highly expressed in CTCs derived from breast cancer patients, in agreement to bioinformatics’ analysis. Quantification of immunofluoresence potentially delineates a subgroup of patients with high expression of CXCR4 and JUNB that could benefit from target therapies.

Citation Format: G. Kallergi, V. Tsintari, S. Sfakianakis, M. Zervakis, D. Mavroudis, V. Georgoulias. CXCR4 pathways in CTCs: from bioinformatics to immunophenotype. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1592. doi:10.1158/1538-7445.AM2015-1592

Abstract P1-04-08: Co-expression of putative stemness and epithelial-to-mesenchymal transition markers on single circulating tumour cells from patients with early and metastatic breast cancer

Background: The detection of circulating tumor cells (CTCs) in peripheral blood (PB) of patients with breast cancer (BC) has been associated with poor disease outcome. Cancer cells with stemness and epithelial-to-mesenchymal transition (EMT) properties are considered to display enhanced metastatic potential. The presence of these features in CTCs could be an important determinant of increased metastatic behaviour. A new methodology was developed to investigate the co-expression of the stemness marker ALDH1 and the EMT marker TWIST on CTCs from patients with early and metastatic breast cancer, at the single-cell level.

Patients and Methods : PBMC’ cytospins were prepared from PB obtained from 80 patients with early and 50 with metastatic breast cancer. Triple immunofluorescence staining was performed using anti-pancytokeratin (A45-B/B3), anti-ALDH1 and anti-TWIST antibodies. Classification of ALDH1 expression levels (high or low) and TWIST subcellular localization (nuclear or cytoplasmic) was performed in HepG2 control cells and three representative BC cell lines, using the ARIOL system. A total of 500.000 PBMCs per patient were subsequently analyzed.

Results : CTCs were detected in 13 out of 80 (16%) and in 25 out of 50 (50%) patients with early and metastatic BC, respectively. Although co-expression of ALDH1 and TWIST was observed on almost all CTCs in both patient groups, CTCs expressing the phenotype ALDH1high/TWISTnuclear were more frequently detected among patients with metastatic compared to early disease (76% vs. 15% of patients, p = 0.0004). Moreover, a higher proportion of ALDH1high/TWISTnuclear CTCs was confirmed in the metastatic setting (62% vs. 13% of CTCs, p<0.0001). On the contrary, the phenotype ALDH1low/TWISTcytoplasmic was more prevalent among CTCs detected in early disease (32% vs. 8% of CTCs, p = 0.0006).

Conclusions : A new assay is provided for the evaluation of ALDH1 and TWIST co-expression at the single-CTC level. CTCs bearing the ALDH1high/TWISTnuclear phenotype were more commonly detected in metastatic compared to early BC, suggesting that this phenotype prevails during disease progression. The characterization of CTCs according to these markers could be used to improve risk stratification in BC.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-04-08.

Abstract P1-04-12: Prognostic value of CTC detection by RT-PCR and the CellSearch system before first-line chemotherapy in metastatic breast cancer

Background: CTCs have significant prognostic role in patients with breast cancer. Several techniques developed for CTC detection might help in monitoring treatment efficacy. The CellSearch System is the only clinically validated for use in patients with metastatic breast cancer (MBC). We have previously shown a concordance between RT-PCR for cytokeratin 19 (CK-19) and CellSearch System in the detection of CTCs in MBC. In this study we aimed to evaluate the prognostic value of CTC detection using these assays in the same cohort of patients. Methods: Blood was obtained from patients with MBC before the initiation of first-line chemotherapy. Different aliquots of the same blood sample were evaluated for the presence of CTCs by RT-PCR for CK-19 mRNA and by the CellSearch System. Disease progression and response to treatment were determined using standard clinical and imaging criteria. Results: In 142 patients with available clinical data, CTC evaluation was performed using both methods. Median age was 60.7 years (range, 23-82), 74.6% were post-menopausal and 16.9% were HER2-positive. CTCs were detected in 52.1% and 36.6% of patients by the CellSearch System (cut-offs ≥2 and ≥5 CTCs/7.5 ml, respectively) and in 38.7% by RT-PCR; 27.5% (cut-off ≥2) and 20.4% (cut-off ≥5) of patients were CTC-positive by both methods. Response rate was 40% in patients with CTCs detected by CellSearch (cut-off ≥2) vs 62% in CTC-negative patients; there was no difference in objective responses using the ≥5 cut-off, or using RT-PCR for CTC detection. Median PFS was 9.0 (cut-off ≥2) and 7.5 months (cut-off ≥5) for CTC-positive versus 20.0 (cut-off ≥2) and 18.7 months (cut-off ≥5) for CTC-negative patients using the CellSearch System (p = 0.0001). No significant difference in PFS was evident according to CTC detection by RT-PCR (10.0 vs 13.1 months, p = 0.253). Median survival was 24.7 vs 57.3 (cut-off ≥2) and 18.5 vs 53.7 (cut-off ≥5) months for CTC-positive vs CTC-negative patients using the CellSearch System (p = 0.0001); by RT-PCR, median survival was 30.3 and 50.1 months for CTC-positive and CTC-negative patients, respectively (p = 0.021). Conclusions: The detection of CTCs before first-line chemotherapy using either the CellSearch System or RT-PCR for CK-19 mRNA has significant prognostic value in patients with MBC.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-04-12.

Abstract P2-01-07: Effect of first-line chemotherapy in the expression of stemness and epithelial-to-mesenchymal transition markers in circulating tumor cells of patients with metastatic breast cancer

Introduction: Cancer stem cells (CSCs) are suggested to be the active source of metastatic spread. Epithelial-to-Mesenchymal transition (EMT) is considered as a crucial event in metastasis, which in addition, generates cells with stemness properties. Circulating tumor cells (CTCs) with stem cell- like and EMT characteristics could escape apoptosis and demonstrate chemoresistance. In the present study we aimed to investigate the co-expression of ALDH1, a stemness marker, and TWIST, an EMT marker, in CTCs from patients with metastatic breast cancer before and after chemotherapy, at the single cell level.

Patients and Methods: Paired PBMCs cytospins were prepared from 154 patients with metastatic breast cancer, before and after first-line chemotherapy. Triple immunofluorescence experiments were performed in samples using the pancytokeratin anti-mouse antibody (A45-B/B3), ALDH1 anti-mouse and TWIST anti-rabbit antibodies, by Zenon technology. ALDH1 expression was characterized as high or low (according to ALDH1 expression quantified in the control cell line HepG2), while TWIST expression was characterized as nuclear or cytoplasmic. 500.000 PBMCs per patient were analyzed using the ARIOL system.

Results: CTCs were identified in 81 (53%) out of 154 patients before treatment, with a total of 2.056 CTCs detected and a median of 2 CTCs per patient (range: 1–600). Up to now, in 38 out of these 81 patients, samples were also evaluated after treatment. A total of 1.232 CTCs were detected in 22 (58%) out of 38 patients, with a median of 10 CTCs per patient (range: 1–828). The great majority of CTCs expressed ALDH1 both before and after chemotherapy, however high ALDH1 expression levels in CTCs were more frequently observed after treatment (91% vs 54%). The median percentage of ALDH1high expressing CTCs per patient was also increased after chemotherapy (86% vs 64%). TWIST expression was observed in the great majority of CTCs both before and after chemotherapy, however nuclear localization of TWIST in CTCs was more often encountered after treatment (92% vs 54%). The median percentage of TWISTnuclear expressing CTCs per patient also increased after chemotherapy (89% vs 48%). High ALDH1 expression in CTCs was positively correlated with nuclear localization of TWIST, both pre- and post-chemotherapy (p = 0.0000001 and p = 0.001, respectively, Spearman analysis). Concerning the co-expression of these molecules, the phenotype ALDH1high TWISTnuclear was the most abundant at both time points, however it was more frequently observed after treatment (90% vs 41% of CTCs). In addition, the median percentage of ALDH1high TWISTnuclear expressing CTCs per patient was also increased after chemotherapy (71% vs 0%).

Conclusions: Stemness and EMT markers are co-expressed in CTCs from patients with metastatic breast cancer, both before and after the first-line chemotherapy. However chemotherapy seems to enrich these characteristics on CTCs, suggesting that CTCs possessing or acquiring these features are resistant to chemotherapy. Evaluation of the post-chemotherapy samples is ongoing and final results will be presented.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-01-07.

Abstract 2379: Expression of truncated HER2 receptor in circulating tumor cells (CTCs) of breast cancer patients

Introduction: HER2 receptor is overexpressed in 15-25% of patients with breast cancer. In HER2 positive breast cancer the administration of trastuzumab has changed the outcome of disease. However, most patients will eventually develop resistance to trastuzumab. The presence of a truncated receptor with loss of the extracellular portion of HER2 (p95HER2) has been proposed as a potential mechanism of resistance. Preclinical and clinical data suggest that the expression of p95HER2 is associated with poor overall prognosis, resistance to trastuzumab and sensitivity to lapatinib, a dual EGFR and HER2 tyrosine kinase inhibitor. We have recently shown that approximately 50% of breast cancer patients express HER2 in their CTCs (Kallergi et al., 2007; Kallergi et al., 2008). The aim of the present study was to characterize, for the first time, the expression of p95HER2 in CTCs of breast cancer patients. Methods: Triple staining immunofluorescent (IF) experiments were performed in peripheral blood mononuclear cells (PBMC) cytospins of patients with early (n=24) and metastatic (n=33) breast cancer who were CK-19 mRNA-positive by real time PCR. Pancytokeratin A45-B/B3 antibody (as a marker of CK-positive cells) was coupled with antibodies against the extracellular and the intracellular domains of HER2. Slides were analysed with either confocal laser scanning microscopy or with the Ariol system. Results: Cytokeratin positive cells were identified in 17 (71%) out of 24 early and in 20 (61%) out of 33 metastatic patients. HER2 positive CTCs were identified in 53% of early and 50% of metastatic CTC-positive breast cancer patients. HER2-positive CTCs lacking the extracellular domain of the receptor (p95HER positive CTCs) were identified in 35% of metastatic and 12% of early breast cancer patients. Exclusively p95HER2 positive CTCs were detected in 12% of patients with metastatic but not in patients with early disease. Conclusions: These data suggest that the truncated p95HER2 receptor is expressed in CTCs of both early and metastatic breast cancer patients. This finding has important therapeutic implications and may explain the observed increased efficacy of the trastuzumab plus lapatinib combination in HER2 positive breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2379. doi:1538-7445.AM2012-2379

Abstract 3411: A pilot feasibility study to evaluate the efficacy of lapatinib in the elimination of HER2-positive circulating tumor cells in peripheral blood of women with metastatic breast cancer

Background: The monitoring of circulating tumor cells (CTCs) detected in peripheral blood (PB) of patients (pts) with metastatic breast cancer (BC) has been proven a potent prognostic tool. CTCs detected after the completion of therapy are theoretically chemo- and/or hormone-resistant and could lead to disease progression. EGFR and HER2 expression has been demonstrated in CTCs from pts with BC. In the present trial we aimed to evaluate the efficacy of lapatinib, a dual EGFR and HER2 tyrosine kinase inhibitor, in eliminating HER2 positive (+) CTCs of women with metastatic BC. Pts and methods: Pts with metastatic BC and HER2+ CTCs detected despite disease stabilization or response after the completion of prior therapy were eligible. Pts received lapatinib, 1500 mg/day orally till disease or CTC progression, whichever occurred first. HER2 expression was evaluated in cytospins of peripheral blood mononuclear cells’ (PBMCs) prepared from PB obtained at baseline and monthly thereafter. Cytospins were stained with HER2 along with cytokeratin antibody; a total of 10^6 PBMCs/pt were analyzed by double immunofluorescence. Results: Nineteen pts were enrolled from September 2008 to October 2011. Median age was 62 years, 12 (63.2%) pts were post-menopausal and 2 had HER2+ tumors. Twelve (63.2%) pts had visceral disease and 7 (36.8%) had received β3 lines of treatment. One pt discontinued treatment prior to the completion of the first cycle due to toxicity and 2 pts are not evaluable yet. The median duration of treatment was 4.0 (range, 0.5 - 34.0) months (mo). CTC counts declined in 15 out of 16 pts during treatment with a maximum percentage of decrease of 100% in all of them. The median time to and the median duration of nadir CTC counts were 1 mo (range, 1 - 3 mo) and 1 mo (range, 0 - 7 mo), respectively. Prior to the second treatment cycle, a decrease in CTC counts was observed in 14 (88%) pts, in 1 (7%) the CTC count increased by 33% and in 1 (7%) remained stable. Median percentage of CTC count decrease per pt was 100% (range, 45-100%). At baseline, a total of 2642 HER2+ CTCs were detected (median: 79/pt, range 2 - 617), whereas after the completion of first cycle a total of 430 HER2+ CTCs were identified (median: 0, range 0 - 223). Disease evaluation revealed stable disease in 5 pts and progressive disease in 11. In pts with stable disease a sustained decrease in CTC counts over 2 to 7 mo was observed. On the contrary, in 9 out of 11 pts with disease progression, the decrease in CTC counts was short-lasting (median 1.0 mo, range 0 - 4). Conclusions: Lapatinib is effective in decreasing HER2+ CTCs in pts with metastatic BC, irrespective of the HER2 status of the primary tumor. Sustained CTC reduction was associated with disease stabilization. The above results suggest that tailoring therapy according to targets present on CTCs could be an effective therapeutic strategy in BC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3411. doi:1538-7445.AM2012-3411

Trastuzumab decreases the incidence of clinical relapses in patients with early breast cancer presenting chemotherapy-resistant CK-19mRNA-positive circulating tumor cells: results of a randomized phase II study

BACKGROUND

Since the detection of circulating tumor cells (CTCs) which express HER2 is an adverse prognostic factor in early breast cancer patients, we investigated the effect of trastuzumab on patients' clinical outcome.

PATIENTS AND METHODS

Seventy five women with HER2 (-) breast cancer and detectable CK19 mRNA-positive CTCs before and after adjuvant chemotherapy, were randomized to receive either trastuzumab (n=36) or observation (n=39). CK19 mRNA-positive CTCs were detected by RT-PCR and double stained CK(+)/HER2(+) cells by immunofluorescence. The primary endpoint was the 3-year disease-free survival rate.

RESULTS

Fifty-one (89%) of the 57 analyzed patients had HER2-expressing CTCs. After trastuzumab administration, 27 of 36 (75%) women became CK19 mRNA-negative compared to seven of 39 (17.9%) in the observation arm (p=0.001). After a median follow up time of 67.2 months, four (11%) and 15 (38%) relapses were observed in the trastuzumab and observation arm, respectively (p=0.008); subgroup analysis indicated that this effect was mainly confined to women with >3 involved axillary lymph nodes (p=0.004). The median DFS was also significantly higher for the trastuzumab-treated patients (p=0.008).

CONCLUSION

Administration of trastuzumab can eliminate chemotherapy-resistant CK19 mRNA-positive CTCs, reduce the risk of disease recurrence and prolong the DFS.

P4-07-20: Apoptosis in Circulating Tumor Cells (CTCs) of Early and Metastatic Breast Cancer Patients

Background: Metastasis has been associated with the presence of circulating (CTCs) and disseminated (DTCs) tumor cells in peripheral blood and bone marrow of breast cancer patients, respectively. Recent studies have confirmed that the detection of CTCs and DTCs represents a strong and independent prognostic factor for decreased disease-free and overall survival. However, it is not clear so far whether all CTCs are capable to generate metastasis or some of them are destined to die. The aim of the present study was to analyze the presence of apoptotic CTCs in patients with early and metastatic breast cancer. Patients and methods: Double staining immunofluorescent (IF) expreriments were performed in peripheral blood mononuclear cells (PBMC) cytospins of patients with early (n=23) and metastatic breast cancer (n=29), prior to the initiation of adjuvant and first-line chemotherapy, respectively. Pancytokeratin A45-B/B3 antibody (as a marker of CK-positive cells) was coupled with either M30 (marker of apoptotic cells) or Ki67 (marker of proliferating cells) antibodies. Apoptotic CTCs were also evaluated using a polycaspase detection kit. Results: Significantly lower proportions of apoptotic CTCs were detected in metastatic compared to early breast cancer patients using the polycaspase kit (3% vs 49%, p=0.0001). These results were confirmed with M30 staining (32% vs 67%, in metastatic and early disease, respectively, p=0.023). The median percentage of apoptotic CTCs per patient was also lower in advanced compared to early disease patients (0% vs 100% with the polycaspase kit and 15% vs 70% with M30 staining). Ki67 positive CTCs were identified in 56% of early and metastatic patients, while the ratio of Ki67-positive/Total CTCs was 15% and 36% respectively. Conclusions: Apoptotic CTCs are more commonly observed in early compared to metastatic breast cancer, whereas, Ki-67 positive CTCs are more frequently encountered in metastatic disease. The differential incidence of apoptotic and proliferative CTCs in early and metastatic disease is probably related to disease progression. The evaluation of these markers in CTCs from patients with breast cancer may provide useful prognostic information and could be used to monitor the effectiveness of therapy.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-07-20.

P4-07-15: Insulin-Like Growth Factor Receptor I (IGFIR) Expression in Circulating Tumor Cells (CTCs) of Patients with Early and Metastatic Breast Cancer (BC)

Background: Components of the insulin-like growth factor system are deregulated and IGFIR overexpression is commonly observed in BC, however the expression of the receptor in CTCs of patients with BC has not been studied.

Methods: IGFIR expression was assessed in CTCs from 65 patients with early and 101 with metastatic breast cancer before the start of adjuvant and first-line chemotherapy, respectively. Peripheral blood mononuclear cells’ (PBMCs) cytospins were stained with a monoclonal A45-B/B3 anti-cytokeratin (CK) antibody and IGFIR β-subunit anti-rabbit antibody. IGFIR(+)CK(+) CTCs were detected using immunofluorescent microscopy (Ariol system). Phosphorylated IGFIR was also evaluated after staining with phospho-IGFIR-β (Tyr1131)/Insulin Receptor-β (Tyr1146) antibody.

Results: CK(+) CTCs were detected in 23 (35.3%) patients with early and 48.5% with metastatic BC. IGFIR(+) CTCs were identified in all (100%) patients with early and in 38 (78%) out of 49 patients with metastatic BC (p=0.014). Eighteen (78%) out of 23 patients with early disease had exclusively IGFIR(+) CTCs and 5(22%) had both IGFIR(+) and IGFIR(−) CTCs. There were no patients in whom exclusively IGFIR(−) CTCs were identified. The respective values in patients with metastatic disease were 19 (39%), 19 (39%) and 11 (22%) (p=0.004, compared to early disease). The median percentage of the expression of IGFIR(+) and IGFIR(−) CTCs per patient was 100% (range 25–100) and 0% (range 0–75), in early and 68% (range, 0–100) and 32% (range 0–100), in metastatic disease, respectively (p=0.003). A total of 222 and 386 CTCs were detected in patients with early and metastatic disease, respectively. IGFIR expression was observed in 84% and 64% of all detected CTCs in adjuvant and metastatic patients, respectively (p<0.001). Phosphorylated IGFIR has been evaluated in PBMCs’ cytospins from 6 patients with adjuvant and 6 with metastatic disease. Interestingly, among 18 CTCs detected in early BC, all expressed phosphorylated IGFIR, whereas, among 34 CTCs identified in metastatic patients, none expressed the phosphorylated form of the receptor. The evaluation of phosphorylated IGFIR is ongoing and updated results will be presented.

Conclusions: IGFIR expression is commonly observed in CTCs of patients with BC. IGFIR expression is detected in a higher proportion of patients and in a higher proportion of the total number of CTCs identified in early compared to metastatic disease. The above observations suggest that metastatic progression is associated with loss or downregulation of IGFIR expression in breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-07-15.

Abstract PD04-04: Cytokeratin-19 mRNA Positive Circulating Tumor Cells during Follow-Up of Patients with Early Breast Cancer: Prognostic Relevance for Late Relapse

PURPOSE: We reported previously that the detection of CK-19 mRNA-positive circulating tumor cells (CTCs) after adjuvant chemotherapy in patients with early breast cancer is associated with poor clinical outcome. Reliable prognostic markers for late disease relapse are not available. In this study we investigated the prognostic value of CTCs’ detection during the first 5 years of follow-up in predicting late disease relapse. PATIENTS AND METHODS: Blood was obtained from 281 patients with early breast cancer who had not experienced disease relapse during the first two years of follow up. CTCs were detected using a real-time reverse transcriptase polymerase chain reaction for CK 19 mRNA after the completion of adjuvant chemotherapy and every six months thereafter for a 5-year follow up period. Patients were classified into four groups based on the CTCs’ status during the first two years and the subsequent three years of follow up (persistently negative, persistently positive, negative turned to positive and the opposite).

RESULTS: The vast majority of patients (92.9%) received some kind of hormonal therapy in addition to chemotherapy. Sixty-nine (24.6%) patients remained CTCs-free throughout the 5-year period. A change in CK-19 mRNA status was observed in 126 (44.9%) patients; 60 (21.4%) patients with initially CK-19 mRNA-positive CTCs during the first 24 months turned CTC-negative afterwards while 66 (23.5%) patients who were initially CTC-negative became CTC-positive. Eighty-six (30.6%) patients remained persistently CK-19 mRNA-positive for the entire 5 years. After 94 months of median follow up (range: 51-147), the relapse rate for each of the above groups of patients is illustrated in the following table.

Table 1: CTCs’ detection status and risk of late disease repapse.

Compared to the persistently negative, only the group of CK-19 mRNA-persistently positive patients had a statistically significant higher risk of relapse (38.4% versus 7.2%, p< 0.001), shorter progression-free survival (not reached vs 135 months, P<0.001) and significant difference in overall survival (not reached vs 146 months, p=0.045).

CONCLUSION: Persistent detection of CK-19 mRNA-positive CTCs in the blood during the first 5 years of follow up after adjuvant chemotherapy is associated with an increased risk of late disease relapse indicating the presence of chemotherapy-and hormonetherapy-resistant residual disease. This prognostic evaluation may be useful when deciding on subsequent adjuvant systemic therapy.

VEGF, VEGFR2 and HIF-1α expression in circulating tumor cells (CTCs) of breast cancer patients

Abstract #1028

Background: Development of metastasis is associated with the presence of circulating (CTCs) and disseminated (DTCs) tumor cells in peripheral blood and bone marrow of breast cancer patients, respectively. Hypoxia and Vascular Endothelial Growth Factor (VEGF) play an important role in angiogenesis. There is no data published concerning the expression of HIF-1α and VEGF/VEGFR in CTCs. Methods: Double staining immunofluoresent experiments were designed to test the expression of VEGF, VEGFR and HIF-1α in CK (Cytokeratin)-positive CTCs from 34 metastatic breast cancer patients. PBMC cytospins were double stained with a monoclonal pancytokeratin antibody (A45-B/B3) along with each of the following: VEGF, VEGFR2 or HIF-1α polyclonal antibodies, respectively. Results: According to our experiments, CTCs from 62%, 47% and 76% of patients expressed VEGF, VEGFR2 and HIF-1α, respectively. In addition, VEGF, VEGFR2 and HIF-1α were expressed in 73%, 71% and 56% of the total number of examined CTCs, respectively. In 24% of the patients CTCs expressed all the investigated molecules. VEGF expression in CTCs was confirmed by performing RT-PCR with VEGF-specific primers in immunomagnetically-separated epithelial cells. Double and triple staining experiments and confocal microscopic analysis of immunomagnetically-isolated CTCs confirmed that VEGF was co-expressed with HIF-1α and VEGFR. Discussion: VEGF and VEGFR2 colocalization in CTCs indicate the presence of an autocrine loop in these cells. Our results demonstrate VEGF, VEGFR2 and HIF-1α expression in CTCs of patients with metastatic breast cancer and thus constitute the basis for using anti-angiogenic therapy for their elimination.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1028.

Molecular basis of gynecological cancer

Alterations in the cellular genome affecting the expression or function of genes controlling cell growth and differentiation are considered to be the main cause of cancer. Genes that cause cancer are of two distinct types: oncogenes and onco-suppressor genes. The normal proto-oncogene can be converted into an active oncogene by deletion or point mutation in its coding sequence, gene amplification, and by specific chromosome rearrangements. Mutations and abnormal expression in ras, myc, c-erbB-2, and other oncogenes have been reported in several types of gynecological cancer. Onco-suppressor genes are involved in gynecological cancer, their functions are localized in different phases of the cell cycle. Structural changes and deletions of these genes can cause cancer. Mutations in the p53, BRCA1, DCC, and PTEN genes have been reported in gynecological cancers such as ovarian, cervical, and endometrial cancer. Human papillomaviruses are of major interest because specific types (HPV-16, -18, and several others) have been identified as causative agents in at least 90% of cancers of the cervix. In this study we summarize the available information regarding the implication of specific oncogenes, onco-suppressor genes, and HPV in the development of female genital malignancies.