GAINESVILLE---A substance first identified in the bark of an African tree magnifies the tumor-cell killing power of radiation therapy by as much as 500 times in laboratory animals, University of Florida researchers reported today (11/23).
"We are always pursuing new avenues to enhance our conventional cancer therapies, radiation and chemotherapy," said Dietmar Siemann, a professor of radiation oncology in UF's College of Medicine. Siemann, his graduate student Lingyun Li, and pathologist Amyn Rojiani of the Moffitt Cancer Center in Tampa authored the paper in the November issue of the International Journal of Radiation Oncology, Biology, Physics.
"The results with combretastatin A-4 prodrug are very encouraging. We're able to achieve these effects by giving relatively low doses that produce no side effects in mice," Siemann said. Combretastatin A-4 prodrug, one of a new class of compounds that launch an indirect attack on tumors by interfering with their blood supply, is seen as a potentially effective therapy for solid tumors, which represent the vast majority of cancers.
Siemann's research was supported in part by a grant from OXiGENE Inc., the developer of the drug. Earlier this month, the Boston- and Sweden-based biopharmaceutical company announced it has begun Phase I clinical trials in human patients with advanced cancers to test the safety and maximum tolerated doses of combretastatin. Following successful Phase I trials, further clinical testing would be required to measure the drug's effectiveness, to determine dosages and to compare its tumor-destruction results with standard treatments. Combretastatin, a small organic molecule found in the bark of the African bush willow tree Combretum caffrum, was identified a decade ago by George R. Pettit and his colleagues at Arizona State University. In collaboration with the National Cancer Institute and the Gray Laboratory in the United Kingdom, they have since demonstrated it can kill tumor cell
Contact: Victoria White
University of Florida