Abstract 362: Molecular characterization of circulating tumor cells allows stratifying for prognosis in breast cancer patients undergoing neoadjuvant therapy
Authors: König Lisa , Hoffmann Oliver , Kimmig Rainer , Kasimir-Bauer Sabine 
Published: August 2015

Background: Primary systemic neoadjuvant therapy in breast cancer (BC) is considered to convert inoperable to operable primary tumors and is undertaken to improve surgical options. However, patients might have metastatic relapse despite achieving a pathologic complete remission (pCR). Here we characterized CTCs of BC patients before and after primary systemic neoadjuvant therapy by molecular profiling including HER2, the hormonal receptors estrogen (ER) and progesterone (PR), the tumor stemcell marker ALDH1 as well as markers involved in epithelial mesenchymal transition (EMT) to a) correlate these findings with response to therapy, progression free survival (PFS) and overall survival (OS), b) identify insufficiently treated patients for possible secondary treatment options.

Materials and Methods: Two x 5 ml blood samples from BC patients were collected before (n = 142) and after (n = 132) primary systemic therapy. CTCs were analyzed using the AdnaTest BreastCancer (AdnaGen AG) for the detection of EpCAM, MUC-1 and HER-2 transcripts. Expression of the ER and PR receptor was assessed in an additional RT-PCR. Furthermore the recovered c-DNA was additionally multiplex tested for three EMT markers (Twist1, Akt2, PI3Kα) using the AdnaTest EMT and separately for ALDH1 applying the AdnaTest StemCell. The analysis of PCR products was performed by capillary electrophoresis on the Agilent Bioanalyzer 2100.

Results: Before therapy, CTCs were detected in 36/142 (25%) of the patients expressing EpCAM (17%), MUC-1 (37%), HER-2 (79%), ER (23%) and PR (6%), respectively. After therapy, 13/132 (10%) of the patients were still positive for CTCs expressing EpCAM and HER2 (each 54%), MUC-1 (43%), ER (17%) and PR (0%), respectively. In addition, 49% of the patients were positive for at least one of the EMT markers before and 14% after therapy, respectively. For ALDH1, the values were 18% and 12%, respectively. CTCs detected after therapy significantly correlated with therapy response whereas no significant associations were found for all CTC-subgroups with regard to PFS and OS. Interestingly, when CTCs were stratified for ER-pos and ER-neg CTCs, ER-neg CTCs before therapy were significantly correlated with reduced PFS (p = 0.03) and OS (p = 0.05) while ER-neg CTCs in EMT before therapy were associated with reduced PFS (p = 0.05).

Conclusion: CTCs found before treatment, displaying either ER-neg or EMT characteristics, might serve as an indicator for therapy resistant tumor cell populations. On the other hand, patients with ER-pos CTCs before therapy had the best prognosis. In conclusion, these findings indicate that the identification of the molecular CTC-subtype appears mandatory to differentiate such populations that are correlated with poor prognosis but also such CTC that indicate good responsiveness as well as long term benefit of systemic therapeutic regimens.

Citation Format: Lisa König, Oliver Hoffmann, Rainer Kimmig, Sabine Kasimir-Bauer. Molecular characterization of circulating tumor cells allows stratifying for prognosis in breast cancer patients undergoing neoadjuvant therapy. [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 362. doi:10.1158/1538-7445.AM2015-362