The dissemination of tumor cells into the circulation is a necessary but not sufficient step in the metastatic process. Recent trials using an FDA cleared assay, show that circulating tumor cell number is a biomarker of prognosis, which is currently under study as a potential surrogate for survival in a phase 3 registration trial. These cells may also serve as a source of tumor tissue for biologic characterization to guide treatment selection, and to better understand the mechanisms of progression and sensitivity to treatment. Discussants will review the biology of disseminating tumor cells, new methods of isolation and analysis, the use of CTC"s in the development of an androgen receptor signaling inhibitor, and, focused on specific intended uses, discuss the regulatory pathways for qualification.
Special Session: Circulating Tumor Cells: Biology, and Applications for Research and Practice

Microfluidic detection and analysis of circulating tumor cells; Shyamala Maheswaran. Massachusetts General Hospital and Harvard Medical School, Charlestown, MA

Biological properties of disseminating tumor cells in cancer patients; Klaus Pantel. Univ. Medical Ctr. Hamburg-Eppendorf, Hamburg, Germany

Circulating tumor cells in drug development: Lessons from trials with abiraterone; Johann S. de Bono. Royal Marsden Hospital, Sutton, United Kingdom

Qualification of circulating tumor cells as a biomarker: Generating evidence for an intended use; Howard I. Scher. Memorial Sloan-Kettering Cancer Center, New York, NY,