Abstract 1899: Predictive factors of anthracycline or taxan based chemotherapy: Analysis from a randomized phase II trial comparing docetaxel plus cyclophosphamide with epirubicin plus cyclophosphamide followed by docetaxel as neoadjuvant chemotherapy for hormone receptor-negative breast cancer

Abstract

Abstract Background: Taxane-based regimens have been developed and used widely to treat breast cancer. It has therefore become important to identify subgroups of patients in which anthracyclines are indispensable. Thus, we had conducted a randomized phase II NAC study to compare a taxane with and without an anthracycline in hormone receptor (HR) negative breast-cancer subtypes and examined predictive factors for each regimen. Aim: To examine the predictive factors for six cycles of docetaxel and cyclophosphamide (TC6) compared with 5-fluorouracil, epirubicin, and cyclophosphamide followed by docetaxel (FEC-D). Methods: Eligibility criteria were operable HR-negative breast cancer, age younger than 75 years and ECOG PS0-1. According to HER2 status, 103 patients were randomly assigned to TC (75/600 mg/m2) every 3 weeks ×6 or FEC (500/100/500 mg/m2) every 3 weeks ×3 followed by D (100 mg/m2) every 3 weeks ×3. Triple-negative (TN) breast cancer was subdivided by cytokeratin 5/6 and epidermal growth factor receptor into basal- and non-basal subtypes. The association of grade 3 pathological complete response (pCR) was examined with Ki-67, p53, aldehyde dehydrogenase (ALDH) 1 and topoisomerase 2A (TOP2A) by immunohistochemistry and TOP2A by fluorescence in situ hybridization) for each regimen. Results: Ninety-seven of 103 patients were analyzed successfully (50 for FEC-D and 47 for TC6). The pCR rate tended to be higher in FEC-D-treated patients compared with TC6-treated patients (pCR: 36.0 vs. 25.5%, n.s.). FEC-D treatment was significantly more effective than TC6 in basal-type (p=0.033) but not in non-basal and HER2 subtypes. ALDH1 was associated with resistance to both regimens (FEC-D: p=0.047, TC6: p=0.085) Conclusions: TC6 was not more effective than FEC-D in HR negative breast cancer. TC6 was significantly less active than FEC-D in basal subtype, and equivalent to FEC-D in HER2 and non-basal subtypes. ALDH1 could provide a marker for novel strategies such as stem cell-based therapies for breast cancer. The association of BRCAness with pCR is being investigated and will be presented at the meeting. Citation Format: Takashi Ishikawa, Kazutaka Narui, Kazuhiro Shimada, Kumiko Kida, Sadatoshi Sugae, Yasushi Ichikawa, Mikiko Tanabe, Itaru Endo, Mari S. Oba. Predictive factors of anthracycline or taxan based chemotherapy: Analysis from a randomized phase II trial comparing docetaxel plus cyclophosphamide with epirubicin plus cyclophosphamide followed by docetaxel as neoadjuvant chemotherapy for hormone receptor-negative breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1899. doi:10.1158/1538-7445.AM2014-1899