Circulating biomarkers of bevacizumab activity in patients with breast cancer

Purpose: Noninvasive markers of anti-vascular endothelial growth factor (VEGF) therapy are needed. Soluble vascular cell adhesion molecule (sVCAM-1), soluble VEGF receptor-2 (sVEGFR-2), and plasma VEGF levels were assessed as potential biomarkers of therapy with bevacizumab. Tumor samples were evaluated for VEGFR-2 mutations before and after bevacizumab.Experimental Design: Twenty-one patients with breast cancer underwent neoadjuvant treatment with bevacizumab for 1 cycle followed by 6 cycles of bevacizumab, chemotherapy, and filgrastim. Peripheral blood samples were collected at baseline, post cycles 1, 4 and 7. sVCAM-1, VEGF and sVEGFR-2 levels were measured by enzyme-linked immunosorbent assay (ELISA). Exons 17-26 of VEGFR-2 were sequenced on tissue samples from 20 patients at baseline and post cycle 1 to evaluate for tumor mutations.Results: From baseline to post cycle 1, sVCAM-1 and sVEGFR-2 values increased by a median of 180.5 ng/ml (p