Abstract PO5-18-09: Anthracycline-free neoadjuvant therapy with nab-paclitaxel and carboplatin in non-luminal breast cancer: a single-arm phase II trial

Abstract Background Anthracycline and taxane-based chemotherapy are the corner stone of neoadjuvant therapy in early breast cancer. Anthracycline-free regimens have been addressed widely because of cardiac toxicity especially in HER2-positive breast cancer when combining trastuzumab and pertuzumab. Aim of this trial was to assess the efficacy and safety of nab-paclitaxel combined with carboplatin in the neoadjuvant therapy of non-luminal breast cancer. Methods The Neopath trial was a prospective, single-arm phase II trial conducted in Comprehensive Breast Health Center, Ruijin Hospital between April 2019 and October 2021. Patients who had cT2-4NanyM0 or cTanyN1-3M0 triple negative breast cancer (TNBC) or HER2-positive breast cancer were enrolled. Patients were treated with neoadjuvant nab-paclitaxel (100 mg/m2) and carboplatin (area under the curve 2) on days 1, 8, and 15, for four 4-week cycles. Concurrent trastuzumab at 2 mg/kg (loading dose 4 mg/kg) and pertuzumab 420 mg (loading dose 840 mg) were given in patients with HER2-positive tumors. Surgery was performed after 4-6 cycles of neoadjuvant therapy. Trastuzumab and pertuzumab after surgery was continued every 3 weeks for a total duration of 1 year. The primary endpoint was pathological complete response (pCR) rate, defined as no invasive tumor in breast and axillary lymph nodes (ypT0/Tis N0) after neoadjuvant therapy. Secondary endpoints were pCR rate in predefined subgroups, pCR (ypT0 N0), objective response rate (ORR); event-free survival (EFS), breast conservation rate and toxicity. Results A total of 106 patients were enrolled in the study and 99 of them proceeded to surgery. The pCR (ypT0/is N0) rate was 41.41% in total, 33.78% in TNBC and 64.00% in HER2-positive breast cancer. Proportion of patients achieving pCR (ypT0 N0) was 38.38% in total, 31.08% in TNBC and 60.00% in HER2-positive tumors. In the ITT population, 93 patients were event-free at a median follow-up of 24 months, while 5 in TNBC group and 1 in HER2-positive group had relapse or distant metastasis. EFS in patients achieving pCR was higher than patients without pCR (HR=7.328, 95%CI=1.453-36.96, p=0.0158). ORR was 72.49% in total, 67.12% in TNBC and 88.00% in HER2-positive breast cancer. Total breast conservation rate was 10.1% and 12.2% in TNBC, 4.0% in HER2-positive subgroup. The most frequent grade 3 or higher adverse events were neutropenia (57%), vomiting (11%) and thrombocytopenia (8%). Conclusion Neoadjuvant anthracycline-free regimen of nab-paclitaxel combined with carboplatin in non-luminal breast cancer was an effective and well-tolerated regimen. Citation Format: Deyue Liu, Li Zhu, Jiayi Wu, Wei Wang, Shuning Ding. Anthracycline-free neoadjuvant therapy with nab-paclitaxel and carboplatin in non-luminal breast cancer: a single-arm phase II trial abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-18-09.