Abstract P2-16-10: Disease free survival rate with dose dense Doxorubicin and Cyclophosphamide followed by weekly Paclitaxel with Trastuzumab and Pertuzumab (ddACTHP) in patients with HER2-positive early stage breast cancer: A single institution experience

Background: Trastuzumab and pertuzumab (HP) with standard chemotherapy is approved for use in the neoadjuvant setting. We performed a retrospective analysis of patients (pts) treated with dose-dense doxorubicin and cyclophosphamide (AC) → paclitaxel, trastuzumab, pertuzumab (THP) in the neoadjuvant setting followed by adjuvant anti-HER2 therapy. Here we report the invasive disease-free survival (iDFS) rate, defined as the time from surgery to the first documented event of ipsilateral invasive local recurrence, ipsilateral locoregional invasive recurrence, distant recurrence, contralateral invasive breast cancer, or death from any cause Methods: We abstracted medical records of patients who were treated with pertuzumab-based therapy in the neoadjuvant setting from September 1, 2013 to March 1, 2016. Charts were analyzed for pt demographics, stage of breast cancer, surgical data, pathologic complete response (pCR)(ypT0/is ypN0) and information on systemic therapy. Results: Charts from 236 pts were reviewed. One patient was excluded as she developed metastatic disease during NAC and did not have surgery. Median follow up was 3.8 years. Median age was 49 years (range 26-79 years). Of 235 pts, 215 (91%) had operable breast cancer (T1-3, N0-1, M0) of which 10 (4%) had clinical stage I disease (T1N0)]; 225 (96%) had stage II/III (T2-4d N0-3 M0); 18 (8%) had locally advanced disease (T2-3, N2-3, M0 or T4a-c, any N, M0), and 9 (3.8%) had inflammatory breast cancer (T4d, any N, M0). 153 (65%) and 82 (35%) had hormone receptor (HR)-positive and negative diseases, respectively. All patients had HER2-positive breast cancer defined as immunohistochemistry (IHC) 3+ and/or fluorescent in-situ hybridization (FISH) of ≥ 2.0. Median number of preoperative HP cycles was 5.5 (range 1-9). 121pts (51%) underwent mastectomy, 113 pts (48%) underwent lumpectomy, 1 patient underwent axillary dissection only. Out of 235 evaluable pts, 146 (62%) had pCR; 80/153 (52%) with HR-positive and 65/82 (78%) with HR-negative diseases had pCR, respectively. After a median follow-up of 3.8 years, there were 21 iDFS events and 10 OS events (n=9-Breast cancer, n=1-Acute Myeloid Leukemia). The 3-year iDFS was 91% (95% C.I. 88-95%) for all, 94% (95% C.I. 90-98%) for pts w/ pCR, and 87% (95% C.I. 80-95%) for pts w/ non pCR (p-value=0.051). The 3-year OS was 96% (95% C.I. 94-99%) for all, 98% (95% C.I. 95-100%) for pts w/ pCR, and 93% (95% C.I. 88-99%) for pts w/ non pCR (p-value=0.12) Conclusions: At our single center experience, the iDFS and OS for patients who received neoadjuvant ddACTHP followed by adjuvant anti-HER2 treatment was 91% and 96%, respectively. Patients with pCR had better outcomes than those with residual disease. Citation Format: Jasmeet C Singh, Sujata Patil, Larry Norton, Mark Robson, Chau Dang. Disease free survival rate with dose dense Doxorubicin and Cyclophosphamide followed by weekly Paclitaxel with Trastuzumab and Pertuzumab (ddACTHP) in patients with HER2-positive early stage breast cancer: A single institution experience [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-16-10.