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.
Detection of circulating tumor cells (CTCs) in patients with lung carcinoma by real-time fluorescent quantitative-PCR approach before and after chemotherapy
