Extracorporeal Photoimmunotherapy for Circulating Tumor Cells

It is believed that metastasis through the cardiovascular system is primarily caused by circulating tumor cells (CTCs). We report an approach to eliminate circulating tumor cells from the blood stream by flowing the blood though an extracorporeal tube and applying photodynamic therapy (PDT). Chlorin e6 (Ce6), a photosensizer, was conjugated to antibody CD44 in order to target PC-3, a prostate cancer cell line. PC-3 cells were successfully stained by the Ce6-CD44 antibody conjugate. PDT was performed on whole blood spiked with stained PC-3 cells. As the blood circulated through a transparent medical tube, it was exposed to light of a specific wavelength generated by an LED array. A 2 minute exposure was sufficient to achieve selective cancer cell necrosis. Control studies showed no cell death.