Sensitive location and characterization of circulating tumor cells for improving therapy selection and monitoring treatment efficacy

For metastatic disease, biomarker profiling of distant metastases is done only when feasible because biopsy of metastases is invasive and associated with potential morbidity without proven benefit. So although biomarker expression may differ in distant metastases, treatment with targeted therapies is almost always based on biomarker targets derived from a patient¹s primary breast tumor, usually excised years before development of metastatic disease. Circulating tumor cells (CTCs) in the blood have been linked to disease outcome in patients with metastatic breast cancer...We have developed a sensitive CTC detection tool using Fiber Array Scanning Technology (FAST) that can rapidly locate CTCs on a substrate and uses abundant cytokeratins not EpCAM as targets. We have developed a protocol that enables testing for protein expression of 5 markers in addition to the ones needed for CTC identification.