Circulating tumor cells (CTC) and circulating endothelial cells (CEC) in patients (pts) receiving adjuvant bevacizumab (B) plus dose-dense (dd) doxorubicin/cyclophosphamide (AC) followed by nab-paclitaxel (nab-P) for early-stage breast cancer (ESBC).

579 Background: Women with high risk ESBC remain at substantial risk of relapse despite adjuvant chemotherapy (AT). Current testing does not completely stratify individual risk of relapse, or assess response to AT. CTC predict outcome in metastatic BC, and CEC have been associated with response to antiangiogenic therapy. We evaluated CTC and CEC during AT plus the angiogenesis inhibitor B. Methods: In a phase II trial at 2 centers,80 pts with HER2- ESBC were treated with q2 week AC (60/600 mg/m2) × 4 followed by q2wk nab-P (260 mg/m2) × 4 with pegfilgrastin on day 2 plus B for one year (10 mg/kg IV q2wk × 8 with chemotherapy then 15 mg/kg q3wk); radiation and endocrine therapy per standard of care. The primary endpoint was cardiac safety. Blood for CTC and CEC was analyzed at baseline, week 2, 8, 16 and q3 mo for 12 mo. CTC were measured using a 2 step analysis. Cells were enriched using anti-EpCAM coated immunomagnetic beads; CTC were analyzed by multiparametric flow cytometry (FC) and defined as EpCAM+,...