Circulating endothelial cells (CECs), progenitors (CEPs), and circulating tumor cells (CTCs) for prediction of response in patients with advanced breast cancer (ABC) receiving metronomic oral vinorelbine (oV): Preliminary results

e14572 Background: Metronomic administration of chemotherapy given once or more per week with no extended gaps was shown to be effectively anti-angiogenic, causing growth arrest or apoptosis of endothelial cells in tumor neo-vessels. Preclinical and clinical studies indicate that ultra-low concentrations of various microtubule inhibitors inhibit proliferation or migration of endothelial cells. We investigated in a phase II study the activity of metronomic administration of oV in ABC, kinetics and response prediction of CECs, CEPs, CTCs and of other biomarkers of angiogenesis (soluble VEGF, VEGFr2, TSP1, bFGF). CT perfusion scans were also performed. Methods: From February 2008, 47 pts with ABC received oV (50 mg/die TTW). Currently 20 pts are evaluable for both activity and biomarker assessment. Baseline levels of biomarkers of angiogenesis were correlated with clinical response. Results: Shown in Table. Conclusions: We found that the baseline value of apoptotic cells (expressed as % of total cells) was s...