According to Adam Dicker, M.D., Ph.D., associate professor of radiation oncology and director of the Division of Experimental Radiation at Jefferson Medical College of Thomas Jefferson University in Philadelphia, traditionally, most cancer therapies are used in highest possible doses. But anti-angiogenesis drugs have caused people to rethink chemotherapy.
Dr. Dicker and others have previously published research showing that using chemotherapy in lower than usual doses can have antiangiogenic effects in the laboratory.
In the recent study, Dr. Dicker, a member of Jefferson's Kimmel Cancer Center, former graduate student Torian Williams, and their co-workers at Jefferson and GlaxoSmithKline in King of Prussia, Pa., filled pencil eraser-size osmotic pumps with low concentrations of paclitaxel (Taxol) and docetaxel (Taxotere). Such pumps allow drugs to diffuse continuously slowly. They placed the pumps in mice in which human choriocarcinoma - which is a very vascular tumor - had been implanted. The pumps slowly released low doses of the drugs. They found the tumors became smaller because the drugs inhibited the growth of endothelial cells, which are key to the development of new blood vessels.
When they sectioned the tissue and looked at the blood vessels, they found fewer blood vessels in the tumors that were treated with drugs. They also saw no toxic effects in the animals.
They reported their results April 8 at the American Association for Cancer Research meeting in San Francisco.
"These results become important," Dr. Dicker says, "because eventually there will be oral versions of these drugs that are currently given intravenously. It suggests that chronic, low dose concentrations of drug for patients will be effective in treating cancer. Companies are planning to come out with oral versions."
Dr. Dicker and his co-workers plan to expand the work to other cancerous tumors, including breast, prostate and brain tumors.
Editors: This information is embargoed for release April 8 at 4 p.m. EDT (1 p.m. PDT) at the American Association for Cancer Research meeting in San Francisco.
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