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

The detection of circulating tumor cells (CTCs) in peripheral blood may have important prognostic and predictive implications in breast cancer treatment. A limitation in this field has been the lack of a validated method of accurately measuring CTCs. While sensitivity has improved using RT-PCR, specificity remains a major challenge. The goal of this paper is to present a sensitive and specific methodology of detecting CTCs in women with HER-2-positive metastatic breast cancer, and to examine its role as a marker that tracks disease response during treatment with trastuzumab-containing regimens. The study included patients with HER-2-positive metastatic breast cancer enrolled on two different clinical protocols using a trastuzumab-containing regimen. Serial CTCs were measured at planned time points and clinical correlations were made. Immunomagnetic selection of circulating epithelial cells was used to address the specificity of tumor cell detection using cytokeratin 19 (CK19). In addition, the extracellular domain of the HER-2 protein (HER-2/ECD) was measured to determine if CTCs detected by CK19 accurately reflect tumor burden. The presence of CTCs at first restaging was associated with disease progression. We observed an association between CK19 and HER-2/ECD. The association of HER-2/ECD with clinical response followed a similar pattern to that seen with CK19. Finally, the absence of HER-2/ECD at best overall response and a change of HER-2/ECD from positive at baseline to negative at best overall response was associated with favorable treatment response. Our study supports the prognostic and predictive role of the detection of CTCs in treatment of HER-2-positive metastatic breast cancer patients. The association between CK19 and markers of disease burden is in line with the concept that CTCs may be a reliable measure of tumor cells in the peripheral blood of patients with metastatic breast cancer. The association of CTCs at first restaging with treatment failure indicates that CTCs may have a role as surrogate markers to monitor treatment response.

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Prospective monitoring of circulating tumor cells in breast cancer patients treated with primary systemic therapy—A translational project of the German Breast Group study GeparQuattro

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.21085 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 21085-21085 ◽

Cited By ~ 6

Author(s):

V. Mueller ◽

S. Riethdorf ◽

S. Loibl ◽

M. Komor ◽

J. Houber ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Patients ◽

Tumor Cells ◽

Circulating Tumor Cells ◽

Metastatic Breast ◽

Primary Diagnosis ◽

Breast Cancer Patients ◽

Primary Systemic Therapy ◽

Her 2 ◽

The Impact

21085 Background: The impact of circulating tumor cells (CTC) in patients with primary breast cancer is still unclear. Primary systemic treatment (PST) allows the assessment of therapeutic efficacy in breast cancer patients without long follow-up periods. Here we present first results on the presence of CTC in peripheral blood of patients enrolled in the “GeparQuattro” study. Methods: This study incorporates three different chemotherapy approaches and additional Trastuzumab (Herceptin®) treatment for patients with HER-2/neu-positive tumors. Recruitment finished in November 2006 and not all patients have completed therapy yet. We used the CellSearch™ system to evaluate CTC before PST from 245 patients and after PST from 67 patients. CTC from 45 samples were also examined for HER-2/neu expression by immunocytochemistry in the CellSearch™ system. Results: Before PST we detected CTC in 54/245 patients (22%). CTC numbers in 7.5 mL blood ranged between 1 and 200 (mean 6.5). In 8 CTC-positive samples (3.3%) = 5 CTC were found. Her-2/neu-positive CTC were observed in 25/45 cases (55.6%). CTC could be detected in 7/67 patients (10.4%) after PST (1 or 2 CTC). Before and after PST blood was analyzed from 43 patients, 27 of them were CTC-negative at both time points. Ten initially CTC-positive cases were CTC-negative after PST whereas 6 cases were detected CTC-positive after PST although no CTC could be found before PST. Conclusions: With the CellSearch™ system CTC can be detected in non-metastatic breast cancer patients at primary diagnosis and also after PST. To our knowledge, this is the largest study evaluating the presence of CTC in this context. With the availability of response information from more patients, it will be possible to examine the correlation between the incidence of CTC and response as well as kinetics of HER-2/neu expression during Trastuzumab treatment. [Table: see text]

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