TOP2A amplification in breast cancer is a predictive marker of anthracycline-based neoadjuvant chemotherapy efficacy

Anthracycline is a DNA topoisomerase 2-α (TOP2A) inhibitor and its concomitant over expression with Human Epidermal Growth Factor Receptor 2 (HER2) was investigated of being predictive for the response to anthracycline-based chemotherapies in breast cancer. 309 early and local advanced breast cancer patients were treated with anthracycline-based neoadjuvant chemotherapies in intense dose dense (IDD) (CE, Cyclophosphamide + Epirubicin) or conventional (TE, Paclitaxel + Epirubicin) regimens. HER2 proteins were qualitatively analyzed by immunohistochemistry (IHC) of primary tumor core biopsies, and TOP2A gene amplification levels of HER2 over-expressing cases were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). Overall pathological complete response rate (pCR) was achieved in 14.3 %. HER2 was over expressed in 80/309 (25.9 %) cases, of which 61/80 cases have been tested for their TOP2A status. Over expression of HER2 was significantly positively correlated with higher pCR rates compared to low HER2 expression (27.5 % vs. 9.6 %, P < 0.001). Concurrent high TOP2A amplification led to a significantly higher pCR rate compared to low or no TOP2A amplification (56.3 % vs. 13.8 %, P = 0.001). HER2 over expression was associated with a significantly higher pCR rate only when TOP2A was also amplified (56.3 % vs. 9.6 %, P < 0.001), but not when it was deleted or normal (13.8 % vs. 9.6 %, P = 0.183) compared to HER2 low-expressing tumors. The interaction between HER2 or TOP2A and anthracycline-based regimen was observed in IDD and conventional neoadjuvant chemotherapies. The TOP2A amplification is related to anthracycline-based neoadjuvant chemotherapy sensitivity, and TOP2A should be included in future studies in breast cancer as a predictive marker.