Abstract P2-02-03: The Collagen Receptor Endo180: A Metastatic Plasma Marker In Breast Cancer Modulated By Bisphosphonate Treatment

Abstract

Purpose: To establish whether the collagen remodelling receptor, Endo180, should be given consideration as a useful plasma marker in metastatic breast cancer. Patients and Methods: Analysis of MCF-7 and MDA-MB-231 cell conditioned medium validated the anti-human (39.10) monoclonal antibody as suitable for the detection of soluble Endo180 in plasma. Eighty-seven breast cancer patients with early primary, locally advanced and metastatic disease were included in the study. Correlations between Endo180, CA 15–3 antigen (MUC1; mucin 1) and bisphosphonate treatment were investigated. Results: Endo180 was elevated in metastatic compared to early breast cancer (P <.0001) and was able to differentiate locoregional disease and visceral and/or osseous metastasis (P = .0005). In combination CA 15–3 antigen (cut-off: 28 U/mL) and Endo180 (relative plasma level cut-off range: 0.95–1.65) had sensitivity of 94–97% and specificity of 52–68%. Endo180 levels were significantly higher in patients who were treatment naive (2.17 ± 0.82, N = 13) compared to those previously (1.82 ± 0.33, N = 5) or currently (1.37 ± 0.74, N = 24) receiving bisphosphonates (P = .011). In the bisphosphonate naive setting (N = 57) the combination of Endo180 (relative plasma level cut-off range: 0.95–1.65) and CA 15–3 antigen (cut-off: 28 U/mL) had a sensitivity of 87–92% and specificity of 72–79%. Conclusion: Endo180 is a plasma marker with high sensitivity in metastatic breast cancer that can be modulated by bisphosphonate treatment. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-02-03.