P5-13-20: TOP2A Amplification Have Associated with Response to Anthracycline-Based Preoperative Chemotherapy in Primary Breast Cancer.

Abstract Background: Recent studies have suggested that HER2 gene amplification or overexpression have association with sensitivity of anthracycline-based chemotherapy. Preclinical studies found that TOP2A amplification or deletion only could be detected in HER2 amplification or over-expressive cases. And TOP2A protein is the target of anthracycline. In fact, the value of HER2 for predicting response to anthracycline-based chemotherapy in breast cancer may be more likely related to the concomitant amplification of the TOP2A gene. In this study we studied the association between TOP2A gene amplification and response to anthracycline-based preoperative chemotherapy. Methods: 309 early and local advanced breast cancer cases were enrolled in our study. HER2 proteins were qualitatively analysed by IHC, and TOP2A gene alterations were quantified by real-time polymerase chain reaction (RT-PCR) in primary tumor core biopsies from all HER2 over expressive cases. The enrolled patients received an intense dose dense (IDD) (CE, Cyclophosphamide + Epirubicin) or conventionally (TE, Paclitaxel+Epirubicin) scheduled anthracycline- based preoperative chemotherapy. The tumor was evaluated every two cycles. Median time on study for 309 patients with follow-up was 38 months. Results: The pCR was 14.3%. HER2 overexpression was found in 80/309 (25.9%) breast cancer cases, of which 61/80 cases have been tested for TOP2A status. 19/80 cases have not been tested for TOP2A status because of lacking core biopsies tumor tissue after pathological diagnosis. HER2 overexpression was associated with a significantly higher pCR rate compared to HER2 lower expression (27.5% vs. 9.6%, P<0.001). Further analysis was carried on and found the significantly higher pCR rate in TOP2A co-amplified cases compared to TOP2A deleted or normal cases (56.3% vs. 13.8%, P=0.001). HER2 overexpression was associated with a significantly higher pathologic complete response (pCR) rate only when TOP2A was co-amplified (56.3% vs. 9.6%, P<0.001), but not when deleted or normal (13.8% vs. 9.6%, P=0.183), compared to HER2 lower expression tumors. The interaction between HER2 or TOP2A and anthracycline-based regiment was observed not only in IDD but conventionally scheduled preoperative chemotherapy. Discussion: Previous studies demonstrate that TOP2A gene amplification may define a subtype of HER2−positive breast cancer, This subtype of breast cancer may be highly sensitive to anthracycline-based chemotherapy, which may improve progression in HER2 and TOP2A co-amplification cases. Howerver, this viewpoint needs suppose from preoperative chemotherapy. Using RT-PCR to test TOP2A statue from 61 primary breast cancer tumor tissue, we demonstrate that TOP2A amplification breast cancer have highly sensitive to anthracycline-based preoperative chemotherapy. This finding suggests that TOP2A as a predictive marker in breast cancer should be included in future studies. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-13-20.