Are CK+/CD45+ Double-Positive Circulating Cells of Tumor-origin? Characterization in METAstatic Breast Cancer

"* A single blood sample will be taken before initiation of the metastatic treatment line. The volume of total blood sampled is 34mL.~* A tumour sample (FFPE block already archived) from a metastasis (other than bone) if available or, failing this, from the primary breast tumour, will be sent to the sponsor in order to meet the objectives of the study.~Once the blood sample has been taken, patients will have completed their participation in the study."