Early Changes In Angiogenesis And Hypoxia Following Bevacizumab Therapy In Primary Breast Cancer

1066 Background: Bevacizumab (BV), a monoclonal antibody directed against vascular endothelial growth factor (VEGF), is an approved anti-angiogenic agent, but despite its widespread use, little is known about how tumours develop resistance to BV. We have conducted a window-of-opportunity study in which BV is administered as a short-term first-line treatment for primary breast cancer (PBC) patients, and assessed histological markers of tumour angiogenesis and hypoxia before and after therapy. Methods: 47 patients with locally advanced breast cancer were prospectively enrolled. Informed consent was obtained from all patients. A single infusion of BV (15 mg/kg) was given 2 weeks before starting neoadjuvant chemotherapy. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and core biopsies for immunohistochemistry (IHC) analysis were performed immediately prior to and 2 weeks after BV. 36 patients with invasive ductal carcinoma and good quality MRI scans and core biopsies were included in this anal...