Long-term outcomes in patients with PET-predicted poor-responsive HER2-positive breast cancer treated with neoadjuvant bevacizumab added to trastuzumab and docetaxel: 5-year follow-up of the randomised Avataxher study

{Background: The open-label, randomised Phase 2 AVATAXHER study (NCT01142778) demonstrated that early PET assessment identified HER2-positive breast cancer patients who responded poorly to neoadjuvant docetaxel plus trastuzumab. Adding neoadjuvant bevacizumab for PET-predicted poor-responders improved pathological complete response (pCR) rates (43.8% vs 24.0%). We investigated long-term study outcomes. Methods: Patients were treated in three groups. All patients initially received two cycles of standard neoadjuvant therapy with [F-18]-FDG PET conducted before each cycle. Those with >= 70% change in the maximum standardised uptake value (Delta SUVmax) received four further cycles of standard neoadjuvant therapy (PET responders). PET-predicted poor-responders (Delta SUVmax <70%) were randomised (2:1) to neoadjuvant therapy with (Group A) or without (Group B) bevacizumab for cycles 3-6. All patients received one further cycle of trastuzumab before surgery plus adjuvant trastuzumab (11 cycles). Findings: 142 patients were randomized and treated (PET responders