Persistence of HER2 overexpression on circulating tumor cells in patients after systemic treatment for HER2-positive breast cancer: Follow-up results of the German Success B trial

• Published in: Journal of clinical oncology Vol. 31; no. 15_suppl; p. 11043
• Main Authors: Neugebauer, Julia Katharina, Rack, Brigitte Kathrin, Jaeger, Bernadette Anna Sophia, Andergassen, Ulrich, Pestka, Aurelia, Fasching, Peter A., Friedl, Thomas W. P., Mouarrawy, Doraid, Clemens, Michael R., Ziemendorff, Gabriele, Heinrich, Georg, von Abel, Ekkehard, Schneeweiss, Andreas, Beckmann, Matthias W., Pantel, Klaus, Janni, Wolfgang
• Format: Journal Article
• Language: English
• Published: 20.05.2013
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/jco.2013.31.15_suppl.11043

Abstract only 11043 Background: The discordance between HER2-expression on circulating tumor cells (CTC) in peripheral blood and the primary tumor has already been shown by our study group for early breast cancer patients with HER2-positive tumors. Here, we compare the results to CTC prevalence and HER2-status of CTC after adjuvant chemotherapy. Methods: The SUCCESS B trial compares FEC-Docetaxel vs. FEC-Docetaxel-Gemcitabine and HER2-targeted therapy as adjuvant treatment for patients with early, HER2-positive, node positive or high risk node negative primary breast cancer. We prospectively analyzed 23ml peripheral blood before and after chemotherapy. CTC and HER2-status were assessed with the CellSearchSystem (Veridex, USA). After immunomagnetic enrichment with an anti-Epcam-antibody, cells were labeled with anti-CK 8/18/19, anti-CD45 antibodies as well as a fluorescein conjugate antibody for HER2-phenotyping. Cutoff for CTC positivity was ≥ 1 CTC. HER-positivity of CTC was assigned if at least one CTC showed strong HER2 staining (3+). Results: CTCs and their HER2-status both before and after chemotherapy were available for 392 patients. In 179 (45.7%) patients no CTC were detected before and after chemotherapy. CTC status changed from positive before to negative after chemotherapy in 104 (26.5%) patients and from negative before to positive after chemotherapy in 69 (17.6%) patients, while 40 (10.2%) patients had a consistently positive CTC status. Patients were significantly more likely to change their CTC status from positive to negative than from negative to positive (p = 0.01). Of the 40 patients with CTC both before and after chemotherapy, 14 (35%) patients had HER2-positive CTC before and after therapy, and 9 (22%) patients had HER2-negative CTC at both time points. 7 (18%) patients had HER2-positive CTC before but not after chemotherapy, while 10 (25%) patients showed the reverse pattern (p = 0.63). Conclusions: Cytotoxic treatment does not seem to influence the HER2-status on CTC. Follow-up data within the Success B trial will analyze the relevance of the HER2-expression of CTC to predict the efficacy of targeted treatment.