Abstract
By attacking established tumor vasculature, vascular disrupting agents (VDAs) represent an alternative approach to the treatment of cancer. One such VDA, 5,6-dimethylxanthenone-4-acetic acid (DMXAA), is scheduled for phase III trials for prostate and lung cancer in combination with conventional chemotherapies. In this work, we identify interferon-β (IFN-β) as a central mediator in the host's response to DMXAA. In mice bearing Lewis lung adenocarcinomas, a single intraperitoneal dose of DMXAA was shown to effect a highly significant reduction in tumor growth rate in wild-type mice that was not seen in IFN-β-null mice. Moreover, intratumoral cytokine expression was shown to be dependent on host-derived IFN-β, as DMXAA-treated IFN-β-null mice demonstrated a lack of induction of not only IFN-β but also the antiangiogenic cytokine, IP-10, in excised tumor tissue. These results support the conclusion that DMXAA derives its potent anticancer properties in part through elicitation of IFN-β expression by host-derived elements.