Abstract 2241: Molecular characterization of circulating tumor cells in head and neck squamous cell carcinoma: Direct comparison of a label-independent size-based microfluidic device with EpCAM-based CTC enrichment

Background: Circulating tumor cells (CTCs) heterogeneity is highly affecting the efficiency of their isolation and thus the reliability of downstream analysis. Especially in Head and Neck Squamous Cell Carcinoma (HNSCC) epithelial mesenchymal transition (EMT) is highly affecting CTC isolation and downstream analysis. We directly compared two different approaches used for CTC isolation, a label-independent size-based microfluidic-based system versus an EpCAM-based positive selection for downstream molecular characterization of CTC both at the gene expression and DNA methylation level in HNSCC.

Methods: Peripheral blood (PB) in EDTA (20mL) was collected from 50 HNSCC patients and 18 healthy donors (HD). A size-based microfluidic device (Parsortix, ANGLE) and an EpCAM-based positive immune-magnetic isolation procedure were applied in parallel, using 10mL PB in each case. Total RNA was isolated from enriched CTCs and RT-qPCR was used to study the expression levels of CK-19, PD-L1, EGFR, TWIST1, CDH2 and B2M. Real time methylation specific PCR (MSP) was used to study the methylation status of SOX17, RASSF1A and MLL3 genes in DNAs isolated from the same enriched CTCs.

Results: In identical blood draws, the label-free size-based CTC-isolation system was superior in terms of sensitivity when compared to the EpCAM-based CTC enrichment, since a significantly higher percentage of identical PB samples was found positive for all genes tested both at the gene expression and DNA methylation level, while the specificity was not affected.

Conclusions: In HNSCC CTC molecular characterization at the gene expression and DNA methylation level should be based on a label-free size-based isolation system.

Citation Format: Martha Zavridou, Sophia Mastoraki, Areti D. Strati, George Koutsodontis, Apostolos Klinakis, Amanda Psyrri, Evi S. Lianidou. Molecular characterization of circulating tumor cells in head and neck squamous cell carcinoma: Direct comparison of a label-independent size-based microfluidic device with EpCAM-based CTC enrichment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2241.

Abstract 2290: Expression pattern of androgen receptor (AR), splice variant 7 (AR-V7) and splice variant 567 (AR-567) in circulating tumor cells and paired plasma-derived exosomes in metastatic castration resistant prostate cancer

INTRODUCTION: Androgen-receptor splice variant 7 (AR-V7)is a highly promising liquid biopsy predictive biomarker indicating primary or acquired resistance to novel androgen receptor signaling inhibitors in metastatic castration resistant prostate cancer (mCRPC). We present for the first time the expression pattern of AR-FL, AR-V7, and AR-567es at a quantitative level in circulating tumor cells (CTCs) and paired plasma-derived exosomes in mCRPC.

METHODS: We first developed and analytically validated a novel multiplex RT-qPCR assay for AR full length (AR-FL), AR-V7, AR-567es and AR-total. We then quantified the expression levels of AR-splice variants, CK-19 (epithelial marker) and B2M (reference gene) in EpCAM+ CTCs and paired plasma-derived exosomes isolated from peripheral blood (20mL) of 62 mCRPC patients and 10 healthy donors.

RESULTS: In CTCs AR-FL was detected in 57/62(92%),AR-V7 in 32/62(52.0%),AR-567es in15/62(24.2%) and AR-total in 56/62(90.0%). In paired plasma-derived exosomes, AR-FL was detected in 45/62(72.5%), AR-V7 in 4/62(6.5%), AR-567 in 2/62(3.2%) and AR total in 47/62(75.8%).CK-19 expression was detected in 18/62(29.0%) of CTCs and in 28/62(45.2%) of exosomes. In all cases AR splice variants were expressed at higher levels in CTCs than in paired exosomes, while AR-V7 was detected at higher percentages than AR-567es.

CONCLUSIONS: Our results reveal for the first time a remarkable heterogeneity on the expression levels of AR-FL, AR-V7 and AR-567es in EpCAM+ CTCs and paired exosomes between individual mCRPC patients. The clinical significance of this finding will be further investigated in large patient cohorts in respect to therapy response.

Citation Format: Areti D. Strati, Martha Zavridou, Evangelos Bournakis, Sophia Mastoraki, Evi S. Lianidou. Expression pattern of androgen receptor (AR), splice variant 7 (AR-V7) and splice variant 567 (AR-567) in circulating tumor cells and paired plasma-derived exosomes in metastatic castration resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2290.

Abstract 503: Molecular characterization of in vivo isolated EpCAM-positive circulating tumor cells in breast cancer

Introduction: In the early stages of cancer, the chance to detect rare CTCs is increasing by increasing the sample volume. The aim of our study was to evaluate the diagnostic sensitivity of a novel clinical device for the in-vivo isolation of EpCAM-positive CTCs (CellCollectorTM, GILUPI, GmBH), by using highly sensitive RT-qPCR molecular assays.

Patients and methods: 29 breast cancer patients without overt metastases before the beginning of adjuvant chemotherapy (M0), 26 breast cancer patients with overt metastases before starting of therapy (M1) and 12/26 of them before the second cycle of therapy (M2), as well as 18 healthy donors participated in the study. After in-vivo isolation, total RNA was extracted from captured cells, lysed in Trizol, followed by cDNA synthesis. RT-qPCR was used for the molecular characterization of captured cells, for: CK-19, HER-2, TWIST1, VEGF, ER, PR, EGFR, CD44, CD24, and ALDH1, while B2M was used as a reference gene. Peripheral blood was also collected for CTC analysis by the FDA cleared CellSearchTM system. In addition, immunofluorescence staining of cytospins was performed and screened for CTCs using the ARIOL system, using ER, HER2, CK (8, 18, 19) and CD45 for CTC identification.

Results: Results are shown in Table 1. At least one gene was expressed in 10(34.5%) of M0, 15(57.7%) of M1 and 4(33.3%) of M2 patient groups, but in none of healthy donors 0/18(0%). CellSearchTM gave positive results in 5(17.2%) of M0, 10(38.5%) of M1 and 0(0%) of M2. Immunofluorescence (Ariol system) was positive for ER, HER2, CK (8, 18, 19) in 5/15(33.3%) M0, in 4/12(33.3%) M1 and in 1/7(14.3%) M2 groups. Table 1.Gene expression in CTCHealthy N = 18M0 N = 29M1 N = 26M2 N = 12CK-190 (0%)6(20.7%)6 (23.1%)2 (16.7%)HER20 (0%)2 (6.9%)0 (0%)0 (0%)ER0 (0%)2 (6.9%)0 (0%)0 (0%)PR0 (0%)0 (0%)0 (0%)0 (0%)EGFR0 (0%)0 (0%)0 (0%)0 (0%)TWIST10 (0%)1 (3.4%)0 (0%)2 (16.7%)VEGF0 (0%)3 (10.3%)5 (19.2%)1 (8.3%)CD44+/CD24−,0 (0%)4 (13.8%)3 (11.5%)1 (8.3%)ALDH1high/CD24−,0 (0%)2 (6.9%)8 (30.8%)1(8.3%)

Conclusions: In-vivo isolation of CTC is minimally invasive, and in combination with high specific and sensitive RT-qPCR assays for CTC detection and molecular characterization seems promising. Comparison studies with the CellSearch and immunofluorescence have shown poor agreement. These results should be validated in large patient cohorts, and in respect to the clinical outcome.

Citation Format: Areti D. Strati, Martha Zavridou, Galateia Kallergi, Eleni Politaki, Tobias Gorges, Andra Kuske, Anna-Lena Bohnen, George Koutsodontis, Amanda Psyrri, Klaus Lucke, Vasilis Georgoulias, Klaus Pantel, Evi Lianidou. Molecular characterization of in vivo isolated EpCAM-positive circulating tumor cells in breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 503.

Abstract 4018: Development and analytical validation of a novel real-time multiplex RT-qPCR assay for the simultaneous quantification of ER, PR, HER-2 and EGFR mRNA expression in circulating tumor cells of breast cancer patients

Introduction: Circulating Tumor Cells (CTCs) represent an important biological link in the spread of breast cancer from primary to metastatic disease. CTCs have already been established as strong predictors of prognosis in patients with metastatic breast cancer. Triple-negative breast cancers have a more aggressive clinical outcome than other forms of breast cancer. The aim of our work was to develop a quantitative real-time multiplex RT-qPCR assay for studying the expression of ER, PR, HER-2 and EGFR in CTC of breast cancer patients.

Materials and Methods: A quadruplex quantitative real time RT-qPCR assay for ER, PR, HER-2 and EGFR was developed based on the de novo in-silico design of eight primers and four dual hybridization probes. All primers and probes were designed to avoid cross-reactions and primer dimer formation and to match the assay conditions, such as amplicon sizes, and melting temperatures. The specificity of all primer and hybridization probe sequences was first tested by homology searches in the nucleotide database (NCBI, nucleotide BLAST). Each probe set included a 3′-fluorescein (F) donor probe and a 5′- LC acceptor probe that was different for each gene set: ER at 610nm, PR at 640nm, HER-2 at 670nm, EGFR at 705nm. A color compensation test was performed by using pure dye spectra so that spectral overlap between dyes was corrected. The LightCycler 2.0 platform, (Roche, Diagnostics) was used since it allows detection of six multiple reporter dyes in the same capillary. The assay was designed, so that only 1 μL of cDNA is used and the total reaction volume is 10 μL.

Results: The assay sensitivity was evaluated by performing spiking experiments. For this reason known numbers of MCF7 and SKBR-3 cells, as well as external quantification calibrators ranging from 105 copies/μL to 10 copies/μL, were used. The specificity was evaluated by carefully designed cross reaction studies, performed for each gene target in the presence of all other targets. Our assay, under optimized conditions has shown a very high specificity for each analyte.

Conclusions: We report for the first time a highly sensitive, specific and reproducible quantitative multiplex real-time RT-qPCR assay for the simultaneous quantification of ER, PR, HER-2 and EGFR. The assay is currently validated in CTC isolated from a large number of breast cancer patients.

Citation Format: Areti D. Strati, Evi S. Lianidou. Development and analytical validation of a novel real-time multiplex RT-qPCR assay for the simultaneous quantification of ER, PR, HER-2 and EGFR mRNA expression in circulating tumor cells of breast cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4018. doi:10.1158/1538-7445.AM2014-4018

Abstract 1465: Prognostic significance of stem cell and EMT phenotype in Circulating Tumor Cells

Background: Circulating tumor cells (CTCs) are associated with prognosis and can be used as a liquid biopsy for repeated follow up examinations. The subpopulation of CTCs that successfully establish distant metastases share EMT and stemness features. These cells have been found to be associated with resistance to anti-cancer therapies and treatment failure.

Patients and methods: Peripheral blood (20 mL in EDTA) was obtained and after density gradient centrifugation, immunomagnetic Ber-EP4 coated capture beads were used to enrich for epithelial cells from 102 patients with early breast cancer and 23 patients with verified metastasis. Messenger RNA was isolated from enriched epithelial cells using oligo (dT)25 coated magnetic beads. After cDNA synthesis the expression of CK-19, MAGE-A3, HER-2, PBGD and CD24, CD44, ALDH1, HPRT was tested, using two different quadruplex RT-qPCR assays. Moreover we performed RT-qPCR for the expression of TWIST1, hMammaglobin and hTERT α+β+.

Results: The presence of circulating tumor cells was evaluated using CK-19, MAGE-A3, HER-2, hTERT α+β+, and mammaglobin gene transcripts. In 102 operable breast cancer patients 31 patients (30.4%) were found positive for the presence of CTCs. CTC biomarkers were significantly correlated with lymph nodes (P=0.032). In the CTC+ group, 10 patients (32.3%) were positive for TWIST1 and 16 (51.6%) were positive for CD44+/CD24-/low and ALDH1+ cell phenotype. We found a significant correlation between HER2 negative tumors with TWIST1 expression (P=0.027) and Stem Cell phenotype (P=0.012). The detection of both EMT and Stem Cell characteristics was associated with shorter disease-free survival (P=0.024). In the CTC positive group of patients with verified metastasis (39.1%) 1 patient (11.1%) was positive for TWIST1 and 4 (44.4%) were positive for CD44+/CD24-/low and ALDH1+ cell phenotype. The detection of CK19+, Stem Cell and Stem Cell and/or EMT phenotype was associated with shorter overall-free survival (P=0.036, P=0.001 and P=0.002).

Discussion: CTCs in breast cancer patients share both stem cell and/or EMT phenotype. The detection and molecular characterization of CTCs with an EMT or stem cell-like characteristics could be a powerful diagnostic tool for the determination of prognosis and designing new therapeutic drugs for the elimination of minimal residual disease.

Citation Format: Areti D. Strati, Vasilis Georgoulias, Evi Lianidou. Prognostic significance of stem cell and EMT phenotype in Circulating Tumor Cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1465. doi:10.1158/1538-7445.AM2013-1465

Abstract LB-306: Multiplex RT-qPCR study on the expression of stem cell markers CD24, CD44, and ALDH1 in circulating tumor cells of breast cancer patients

Background: Molecular characterization of Circulating Tumor Cells (CTC) can give important information on their suspected connection to cancer stem cells. In breast cancer, putative cancer stem cells have been identified to have a CD44+CD24-/low and ALDH1+ cell phenotype. Patients and methods: We developed a tetraplex quantitative RT-qPCR assay for CD24, CD44, ALDH1 and HPRT based on the in-silico design of primers and probes with different fluorescence emission spectra. Specificity and sensitivity experiments were performed using the SKBR-3 cancer cell line. We isolated CTC from peripheral blood according to our previously described methodology (Strati et al, BMC cancer 2011) from 40 patients with early breast cancer before the administration of adjuvant chemotherapy, 23 patients with verified metastasis and 18 female healthy volunteers. We evaluated all our data with respect to CD24, CD44, ALDH1 expression of healthy volunteers using the 2βΔΔCt method. Results: In 23 patients with verified metastasis 9.0% were found to have CD44+CD24-/low phenotype and 13% ALDH1high/CD24-/low phenotype. In 40 operable breast cancer patients 8 patients (20.0%) were found to have CD44+CD24-/low phenotype and 12 patients (30.0%) were found to have ALDH1high/CD24-/low phenotype. CK-19, MAGE-A3, HER-2, TWIST1, hTERT α+β+, and mammaglobin gene transcripts were also quantified in the same samples. Discussion: Molecular characterization of CTC has shown that in breast cancer patients CTCs are partly characterized by a putative stem cell phenotype. The clinical significance of these findings in early breast cancer remains to be elucidated when the clinical outcome of these patients is known.

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 LB-306. doi:1538-7445.AM2012-LB-306

Abstract 86: DNA methylation of tumor suppressor and metastasis suppressor genes in circulating tumor cells

Background: Circulating tumor cells (CTCs) are associated with prognosis in a variety of human cancers and have been proposed as a liquid biopsy for follow up examinations. We show, that established tumor suppressor and metastasis suppressor genes (CST6, BRMS1, and SOX17) are epigenetically silenced in CTCs isolated from peripheral blood of breast cancer patients.

Methods: Peripheral blood was obtained from 56 patients with operable breast cancer, 27 patients with verified metastasis and 23 healthy individuals. Extraction of genomic DNA was performed in the EpCAM positive immunomagnetically selected CTC fraction of peripheral blood mononuclear cells (PBMC). DNA samples were subjected to sodium bisulphite conversion and tested for the presence of methylated and unmethylated gene promoter sequences by methylation specific PCR (MSP). All samples were also checked for CK-19 expression by RT-qPCR.

Results: In CTCs of patients with operable breast cancer, CST6 promoter methylation was observed in 17.9%, BRMS1 promoter methylation in 30.4%, and SOX17 promoter methylation in 53.6%. In CTCs of patients with verified metastasis, CST6 promoter methylation was observed in 37.0%, BRMS1 promoter methylation in 44.4%, and SOX17 promoter methylation in 74.1%.

Conclusions: Our results provide the first evidence that DNA methylation of tumor suppressor and metastasis suppressor genes is a hallmark feature of CTCs and confirm their heterogeneity. Our findings add a new dimension on the malignant nature of CTCs and may underlie the acquisition of malignant properties, including their stemlike phenotype. Moreover, these epigenetic markers open new possibilities for the exploitation of CTCs in monitoring cancer metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 86. doi:10.1158/1538-7445.AM2011-86

Abstract 2040: Gene expression profile of circulating tumor cells in breast cancer by RT-qPCR

Background: Circulating tumor cells (CTCs) are associated with prognosis and can be used 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.

Patients and methods: We 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 compared our results with the CellSearch system in 33 patients with early breast cancer.

Results: RT-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%. The comparison between RT-qPCR and CellSearch, showed that RT-qPCR was more sensitive than CellSearch.

Discussion: Molecular 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.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2040. doi:10.1158/1538-7445.AM2011-2040

Abstract 1142: Development and validation of a multiplexed PCR-coupled liquid bead array for gene expression in circulating tumor cells

INTRODUCTION: The aim of our study was to develop and validate a multiplexed PCR-coupled liquid bead array to detect the expression of multiple genes in Circulating Tumor Cells (CTCs), and application of this assay in peripheral blood samples of breast cancer patients.

PATIENTS AND METHODS: We designed a novel multiplexed PCR-coupled liquid bead array that consist of the following steps: a) in silico designed gene-specific primers and capture probes for CK-19, HER-2, Mammaglobin (hMAM), MAGE-A3, TWIST-1 and PBGD (as a control gene), b) RNA isolation from immunomagnetically enriched CTCs, c) multiplex PCR, d) sequence hybridization array, e) detection in the Luminex platform. We performed extensive optimization experiments using the SKBR3 and MDA-MB-231 cell lines as positive controls, to maximize analytical sensitivity and specificity and we further validated the performance of this array in respect to cross reactivity and intra and inter-precision. Finally, we applied the developed methodology in peripheral blood samples of 37 patients with operable breast cancer, 25 patients with verified metastasis and 17 healthy individuals.

RESULTS: The analytical performance of the developed array was evaluated in tumor cell lines in respect to analytical sensitivity and specificity. Cross reaction studies were performed for each gene target in the presence of all other targets. The assay is highly specific for each gene in complex multiplexed formats, since the discriminatory power of fluorescent bead sets is unique to specifically detect by sequence hybridization the presence of individual gene specific PCR products. The developed liquid bead-based array is highly sensitive, since it can detect the expression of each individual gene at one SKBR3 cell level. The validation of the array included within day and between-days precision studies. None of the genes tested was detected in the CTC fraction of healthy donors while in patients with verified metastasis, CK-19 was detected in 45%, HER-2 in 20%, MAGE-A3 in 30%, hMAM in 15% and TWIST-1 in 20%. In operable breast cancer patients, CK-19 was detected in 13.5%, HER-2 in 5%, TWIST-1 in 16.2%, MAGE-A3 in 37.8% while hMAM was not detected in any sample.

CONCLUSIONS: Our results show that individual gene expression can be readily measured in CTCs using a bead-based platform. This may form an efficient basis for a multiplex approach to measure multiple genes (up to 100) in the same sample, thus saving sample volume and reducing the total cost and time of analysis. This is the first time that the Luminex technology is used for gene expression studies in CTCs.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1142.

Abstract 840: Development and validation of a real-time multiplex PCR assay for the simultaneous quantification of CK-19, MAGE-A3, HER-2 and PBGD in circulating tumor cells of breast cancer patients

Introduction: Circulating tumor cells (CTCs) represent an important biological link in the spread of breast cancer from primary to metastatic disease. CTCs have already been established as strong predictors of prognosis in patients with metastatic breast cancer. The aim of our work was to develop a quantitative real-time multiplex PCR assay for CK-19, MAGE-A3, HER-2 and PBGD and validate its performance in CTCs of early and metastatic breast cancer patients.

Materials and Methods: A tetraplex quantitative real time assay for CK-19, MAGE-A3, HER-2 and PBGD was developed based on the in-silico design of primers and four hybridization probe pairs with different fluorescence emission spectra. The LightCycler 2.0 platform, (Roche, Diagnostics) was used since it allows detection of six multiple reporter dyes in the same capillary. Specificity and sensitivity experiments were performed using the SKBR-3 cancer cell line as a positive control. The method was applied in 73 patients with early breast cancer before the administration of adjuvant chemotherapy, 27 patients with verified metastasis and 17 female healthy volunteers. Peripheral blood (20 mL in EDTA) was obtained and after density gradient centrifugation, immunomagnetic Ber-EP4 coated capture beads were used to enrich for epithelial cells, keeping for each sample two fractions: the CTC and corresponding PBMC fraction. Messenger RNA was isolated from enriched epithelial cells using oligo (dT)25 coated magnetic beads. After cDNA synthesis the expression of CK-19, MAGE-A3, HER-2 and PBGD was tested, in both fractions.

Results: The analytical performance of the method was evaluated in SKBR-3 tumor cell line in respect to analytical sensitivity and specificity. Cross reaction studies, performed for each gene target in the presence of all other targets have shown a very high specificity for each analyte. RNA quality in all samples was evaluated by PBGD gene expression. We found 30/73 (41%) patients with early breast cancer positive for CK-19, 14/73 (19,2%) for MAGE-A3 and 11/73 positive for HER-2 (15,1%). In patients with verified metastasis we found 14/27 patients positive for CK-19 (51.8%) 4/27 for MAGE-A3 (14,8%), 5/27 patients positive for HER-2 (18,5%). In healthy individuals we found 1/17 positive for CK-19 (5,9%) while no samples were found positive for MAGE-A3 and HER-2 (0%).

Conclusions: We report for the first time a highly specific, reproducible and sensitive quantitative multiplex real-time PCR assay for the simultaneous detection of CK-19, MAGE-A3, HER-2 and PBGD. The expression of these genes in CTCs will be further examined in a larger number of patients and results will be correlated with their clinical outcome.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 840.