Abstract P1-14-04: A randomized phase II neoadjuvant (NACT) study of sequential eribulin followed by FAC/FEC-regimen compared to sequential paclitaxel followed by FAC/FEC-regimen in patients (pts) with operable breast cancer not overexpressing HER-2

Background: Neoadjuvant chemotherapy (NACT) is an integral component for locally advanced and large operable breast cancer. The sequence of taxanes followed by anthracyclines has been the standard of care for almost 20 years. Eribulin (E) is a synthetic analogue of halichondrin B with distinct mechanism of action as microtubule dynamics inhibitor. The FDA approved E in 11/2010 for the treatment of patients (pts) with metastatic breast cancer who have previously received at least two chemotherapeutic regimens for the treatment of metastatic disease. Research Hypothesis: Sequential administration of eribulin followed by FAC/FEC-regimen, would have greater pathologic complete response (pCR) rate than sequential administration of paclitaxel followed by FAC/FEC-regimen as primary systemic therapy for woman with operable breast cancer. Methods: This is a phase II, randomized, single institution, open label study. Pts were randomized 1:1 to receive E (1.4 mg/m2 d1 and d8 q 21 days x 4) or paclitaxel (P) (80 mg/m2 weekly x12). Both arms received FAC/FEC regimen x 4 doses followed by surgery. Eligible pts were women age 18 or older, Karnosfky PS 80 – 100, histologically confirmed invasive breast cancer, clinical T2-T3, N0-3, M0, HER2-negative. Baseline LVEF of > 50% and normal hematology, liver and kidney laboratory function tests. Primary endpoint was pathologic complete response (pCR/RCB-0) assessed by residual cancer burden (RCB). [Symmans F, 2007]. This protocol (2012-0167) IRB of The University of Texas, MD Anderson Cancer Center. Results: A preplanned interim analysis aimed to validate trial assumption was conducted after treatment of 54 randomized pts. Between 8/2012 to 7/2014, 54 pts were randomized and 49 were evaluable for pCR(27 P arm and 22 E arm). Tumor response by RCB is shown in the table. pCR rates were 30% and 4.5% in the P and E arm, respectively. 53 pts were evaluable for toxicity. The combination was safe with mostly grade 1 and 2 toxicities in both arms. In the P arm grade 3 peripheral neuropathy and neutropenia was seen in 3% and 7%, respectively. In the E arm one patient died due to multiorgan failure during cycle 1. There was no other grade 3-5 toxicity. Biomarker analysis using CTCs by AdnaTest Breast were evaluated in 39 pts at baseline. 5/39 pts were positive for CTCs. 3 pts had transcripts for EpCAM, 1 for Muc-1 and another had both. 30 pts had an additional sample post therapy. 2 pts were positive for CTC at baseline as well as at follow up (FU) visit at 180 days. None of the samples showed CTC-EMT at baseline or at FU visits. Conclusions: The interim analysis demonstrated that E arm lead to significantly lower pCR/RCB1 rate compared to P arm. Ongoing biomarker analyses include TIL, hot spot mutation analysis (HSMA) and molecular inversion probes (MIP) will be presented at the time of the meeting. Clinical trial information: NCT01593020. Citation Format: Alvarez RH, Koenig KB, Ensor JE, Ibrahim NK, Chavez-MacGregor M, Litton JK, Schwartz Gomez JK, Cyriac A, Krishnamurty S, Caudle AS, Shaitelman SF, Whitman GJ, Booser DJ, Reuben JM, Valero V. A randomized phase II neoadjuvant (NACT) study of sequential eribulin followed by FAC/FEC-regimen compared to sequential paclitaxel followed by FAC/FEC-regimen in patients (pts) with operable breast cancer not overexpressing HER-2. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-04.