Abstract P3-11-16: S0800: Nab-paclitaxel, doxorubicin, cyclophosphamide, and pegfilgrastim with or without bevacizumab in treating women with inflammatory or locally advanced breast cancer (NCI CDR0000636131)

Background. Locally advanced breast cancer (LABC) and inflammatory breast cancer (IBC) remain difficult challenges despite progress in multimodality treatment. The SWOG trial S0800 (clinicaltrial.gov NCT00856492) compared bevacizumab in combination with weekly nab-paclitaxel followed by dose-dense AC to nab-paclitaxel followed or preceded by AC as neoadjuvant treatment for HER2-negative IBC/LABC. The rationale was based on the proposed role of angiogenesis, potential role of improved flow and oxygenation in enhancing the delivery of chemotherapy agents, and the proapoptotic effect with certain chemotherapeutic agents, particularly taxanes.Methods. This was a randomized open-label Phase II trial with an accrual goal of 200 patients equally allocated to either bevacizumab (Arm 1) or no bevacizumab.Two patients were ineligible and five withdrew consent leaving 208 for analysis. The no bevacizumab group was further randomized to two sequences (Arm 2: nab-paclitaxel - AC+PEG-G versus Arm 3: AC+PEG-G- nab-paclitaxel) with 50 patients expected in each sequence. The primary endpoint of this study was pathologic complete response (pCR) defined as no evidence of invasive tumor at the primary site and axillary lymph nodes in the surgical specimen. The power for the primary comparison of bevacizumab (bev) versus no bevacizumab (no bev) ignoring sequence was 80% with a 1-sided α = 0.10. Randomization was stratified by hormone receptor status and type of disease (IBC or LABC).Results 215 patients were accrued May 2010 - September 2012. Most had LABC (88%) versus IBC (12%) and most tumors were hormone-receptor (HR) positive (67%). Fourteen (7%) patients had no definitive surgery (included as no pCR); 135 (65%) had residual disease (no pCR) and 59 (28%) had pCR. The bevacizumab pCR rate was higher (35/96; 38%) than that in the non-bevacizumab arms (24/112; 21%) (exact p=0.021; stratified p=0.015). In HR-positive disease there was slight improvement that was not statistically significant (bev 25% vs. non-bev 18%; p=0.41) while the difference was larger in HR-negative disease (bev 59% vs. non-bev 28%; p=0.014). In LABC the overall pCR rate was 29% with a higher rate in the bevacizumab patients (37% vs. 22%; p=0.035). For IBC there was improvement (30% vs. 14%), but not statistically significant (p=0.61) in a small sample. Overall, Grade 3 and 4 events were common in both (bev 67%; non-bev 65%), but did not differ by treatment. There were 21 deaths with 3-year overall survival (OS) of 87% and 83% for bevacizumab and non-bevacizumab, respectively (log-rank p=0.57).Conclusion Compared with combination anthracycline-taxane neoadjuvant chemotherapy, the Bev-Nab-paclitaxel-AC regimen significantly improved pCR rate overall, primarily for triple negative (TNBC) patients. This neoadjuvant regimen could be a good choice for TNBC/IBC . The observed pCR rate in ER negative disease (59%) suggests that the addition of bevacizumab to a standard chemotherapy backbone may improve outcome in this subset, and justifies further testing of such an approach. Correlative science studies to further delineate the biology of TNBC and the effects of bevacizumab are ongoing.Citation Format: Zeina A Nahleh, William E Barlow, Daniel F Hayes, Anne F Schott, Julie R Gralow, Edith A Perez, William M Sikov, Sudhathi Chennuru, Hamid Mirshahidi, Sarah Vidito, Danika L Lew, Lajos Pusztai, Robert B Livingston, Gabriel N Hortobagyi. S0800: Nab-paclitaxel, doxorubicin, cyclophosphamide, and pegfilgrastim with or without bevacizumab in treating women with inflammatory or locally advanced breast cancer (NCI CDR0000636131) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-11-16.