Results of a multicenter pilot study of weekly nab-paclitaxel, carboplatin with bevacizumab, and trastuzumab as neoadjuvant therapy in HER2+ locally advanced breast cancer with SPARC correlatives

Abstract 527 Background: The addition of targeted therapies to standard chemotherapy has resulted in improved outcomes in metastatic, neoadjuvant and early stage breast cancer. A phase III study in MBC demonstrated improved efficacy with nab paclitaxel (nab-P) compared with standard solvent-based paclitaxel. The secreted protein acidic rich in cysteine (SPARC) is a poor prognostic factor for survival and may mediate enhanced intratumoral accumulation of nab-P via an interaction with albumin. This multicenter phase II pilot study was designed to evaluate the feasibility, safety, and preliminary efficacy of dual VEGF and HER-2 monoclonal antibodies of bevacizumab (B) and trastuzumab (T) administered in with neoadjuvant nab-P and carboplatin (C) with SPARC tumor correlatives. Eligibility: clinical T1c-T4d and/or N0-3, M0 (T1N0M0 excluded) chemo naive, ECOG PS 0-2, normal LVEF, adequate organ function. nab-P 125 mg/m(2) D1, 8, 15 with C AUC 6 D1 q28 days plus T 4 mg/kg load followed by 2 mg/kg/wk and B 5 mg/kg/wk x 6 cycles followed by surgery. Post surgery T and B continued for 52 wks. SPARC tumor expression was measured by immunohistochemistry. 29 pts are enrolled and evaluable for safety. Median age: 52 years (29-76), ECOG PS 0-93%, median tumor size 3.2 cm, 54% ER-/PR-, 72% node positive. G3/4 neutropenia was 38% with no febrile neutropenia. Nonheme toxicity: G3/4 hyperglycemia 10%, proteinuria and hypertension, each in 7%. 8 pts were hospitalized (infection-4, ↓LVEF-1, wound dehiscence-1 pt, other-2). 5 pts did not complete neoadjuvant therapy (↓LVEF-1, noncompliance-1, pt request-3) and 10 pts did not complete post op therapy ((pt request-2, toxicity-3, wound-2, unk-3). Pathologic responses are available for 20 pts. pCR was noted in 13/20 pts (65%) and PR was noted in 7/20 pts (35%). 77% of the pCR pts (10/13) and 86% of the PR pts (6/7) were positive for SPARC. Neoadjuvant B, T with nab-P and C is feasible and highly active with a remarkable pCR of 65%. SPARC tumor correlations with pathologic response data reveal a concordance between the high response rate and high incidence of SPARC positivity. [Table: see text].