An open-label randomized, multicenter, phase II study on neoadjuvant treatment with trastuzumab plus docetaxel versus trastuzumab plus docetaxel plus bevacizumab according to positron emission tomography (PET) value modification in patients with early stage HER2-positive breast cancer (AVATAXHER): Design description

TPS646 Background: For patients with early HER2+ breast cancer at diagnosis, addition of trastuzumab (T) to 6 cycles of preoperative docetaxel (D) can reach a pathological complete response (pCR) in ~50% of cases, and a high rate of conservative surgery. pCR can be predicted by changes of Fluorodeoxyglucose (FDG) tumor uptake evaluated by Positon Emission Tomography (PET) after one cycle of therapy. In order to increase this pCR rate, adding an antiangiogenic compound could be considered. Pre-clinical and phase I-II data support that the combination of bevacizumab (B) and T is synergistic and safe when patients are chemotherapy naïve. The neoadjuvant AVATAXHER trial (EUDRACT 2009-013410-26) investigates the potential increase of pCR rate by combining B with T and D for patients with HER2+ breast cancer who are not predicted for pCR by FDG PET. Methods: In this multicenter, open-label, phase II trial, 2 phases are planned after a selection period: phase I: all patients receive two cycles of therapy combining T (8 mg/kg at the first cycle, then 6 mg/kg) and D (100 mg/m2). FDG PET is also performed within 7 days before cycle 1 (baseline) and less than 3 days before cycle 2 in order to calculate changes of the tumor FDG uptake between baseline and after cycle 1 (ΔSUV). Phase 2: if ΔSUV≥70%, patients will continue to receive T and D for (cycles 3 to 6: D 100 mg/m2 + T 6 mg/kg); if ΔSUV2 + T 6 mg/kg + B 15 mg/kg) or arm B ( cycles 3 to 6: D 100 mg/m2 + T 6 mg/kg). The primary endpoint is pCR rate evaluated post-surgery 4 to 6 weeks after the last treatment of cycle 6. Enrolment began in May 2010 and 125 patients were to be recruited in 26 sites. According to the hypothesis that 60% of patients will have a ΔSUV