A Phase II Study Evaluating the Safety and Efficacy of Sunitinib Malate in Combination With Weekly Paclitaxel Followed by Doxorubicin and Daily Oral Cyclophosphamide Plus G-CSF as Neoadjuvant Chemotherapy for Locally Advanced or Inflammatory Breast Cancer

INTRODUCTION Neoadjuvant chemotherapy is standard treatment for locally advanced (LABC) or inflammatory breast cancer (IBC). We hypothesized adding sunitinib, a tyrosine kinase inhibitor with anti-tumor and anti-angiogenic activity, to an anthracycline and taxane regimen would improve pathologic complete response (pCR) rates to a prespecified endpoint of 45% in patients with HER2 negative LABC or IBC. PATIENTS AND METHODS We conducted a multicenter, phase II trial of neoadjuvant sunitinib with paclitaxel (S+T) followed by doxorubicin and cyclophosphamide plus G-CSF for patients with HER2 negative LABC or IBC. Patients received sunitinib 25 mg PO daily with paclitaxel 80 mg/m2 IV weekly x12 followed by doxorubicin 24 mg/m2 IV weekly + cyclophosphamide 60 mg/m2 PO daily with G-CSF support. Response was evaluated using pCR in the breast and the Clinical-pathologic scoring + estrogen receptor (ER) and grade (CPS+EG) score. RESULTS Seventy patients enrolled and 66 were evaluable for efficacy. Eighteen patients (27%) had pCR in the breast (10 had ER+ disease and 8 had triple negative disease). When defining response as pCR and/or CPS+EG score ≤ 2, 47% were responders. In ER+ patients, 23 (64%) were responders. The most common toxicities were cytopenias and fatigue. CONCLUSIONS Neoadjuvant S+T followed by AC+G-CSF was safe and tolerable in LABC and IBC. The study did not meet the prespecified endpoint for pCR. However, 47% were responders using pCR and/or CPS+EG score ≤2. ER+ patients had the highest response rate (64%). The addition of sunitinib to neoadjuvant chemotherapy may provide promising incremental benefit for ER+ patients.