Abstract P5-16-06: Neoadjuvant weekly carboplatin and paclitaxel followed by dose dense epirubicin and cyclophosphamide in triple negative breast cancer patients: A single arm phase II study from the Belgian Society of Medical Oncology

Introduction: Triple negative breast cancer (TNBC) remains a challenging disease with dismal prognosis. Platinum analogs have not yet shown to improve long term outcome in this setting, but are associated with increased pathological complete response rate (pCR) at the cost of higher toxicity.

Aim: To further increase or maintain the high pCR rate with platinum containing schedules while decreasing toxicity by administering low dose weekly carboplatin instead of high-dose 3 weekly carboplatin as in CALGB 40603.(1)

Patients and methods: We evaluated the tolerability and the impact of the addition of weekly carboplatin (CP) to paclitaxel (P) and dose dense epirubicin-cyclofosfamide (EC) on pCR in an open-label multicenter phase II study in stage II/III TNBC patients (pts). Sixty three pts received dose dense paclitaxel (P:80mg/m2/wk) concurrent with carboplatin (CP: AUC=2) for 12 wks, followed by two-weekly epirubicin (E:90mg/m2) and cyclophosphamide (C:600mg/m2) for 4 cycles. The primary endpoint is pCR in the breast and axilla. Additionally treatment deliveryand adverse events are recorded. A correlative assessment of germline mutations in homologous recombination (HR) genes is planned. Pts are monitored for response by magnetic resonance and mammography and also for relapse free survival and time to treatment failure. The study size sample has been calculated according to the optimal Simon's two-stage design method. The target sample size was 63 patients with 80% power to detect a pCR rate of ≥47% (α= 0.05).

Results: Accrual to the study is completed with 63 eligible pts with operable, noninflammatory stage II and III TNBC included. Most patients were between 40 and 60 yrs old and were clinical stageT2 tumors. Half of the pts were clinically node + and 70% were G3. Sixty six percent had breast conserving surgery. Sixteen out of 26 (61.5%) of the currently evaluable pts achieved a pCR rate in the breast and axilla. The other ongoing patients have not yet reached this endpoint. Four out of 21 evaluable pts that completed the chemotherapy missed two or more doses of CP due to neutropenia(NP) G3/4(2), general deterioration G3(1) and polyneuropathy(PNP) G3(1) and seven pts needed one dose reduction of P and/or CP due to NP G3-4 (3-2) and PNP G2(1) and one abdominal infection.

Conclusion: These preliminary data suggest that the addition of weekly carboplatinum to neoadjuvant paclitaxel and EC is feasible and has a promising pCR rate in the breast and axilla as high as 61.5% in early TNBC pts. More mature toxicity and outcome data and correlation with genome analysis will be presented.

(1) Impact of the addition of carboplatin and/or bevacizumab to neoadjuvant once per week paclitaxel followed by dose-dense doxorubicin and cyclophosphamide on pathologic complete response rates in stage II to III triple-negative breast cancer: CALGB 40603(Alliance) Sikov WM et al. J Clin Oncol 33:13-21; 2014.

Citation Format: Fontaine C, Cappoen N, Renard V, Vuylsteke P, Van Den Bulck H, Glorieux P, t'Kint de Roodenbeke D, Dopchie C, Decoster L, Vanacker L, De Grève J, Awada A, Wildiers H. Neoadjuvant weekly carboplatin and paclitaxel followed by dose dense epirubicin and cyclophosphamide in triple negative breast cancer patients: A single arm phase II study from the Belgian Society of Medical Oncology [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-06.