(Philadelphia, PA) -- New approaches are needed to treat solid malignant tumors that cannot be removed surgically and are resistant to traditional powerful chemotherapy drugs. In a Phase I clinical trial, a team of researchers at the University of Pennsylvania Cancer Center has found that patients with solid cancerous tumors were able to safely tolerate a new drug, originally derived from a South African willow bush, that interacts with the tumor's blood supply. James P. Stevenson, MD, assistant professor of medicine at Penn and lead author of the study, will present these findings at the 91st American Association of Cancer Research Meeting on Tuesday, April 4, 2000 in San Francisco.
Combretastatin A4 phosphate is a drug that is classified as a vascular targeting agent. It selectively targets and reduces or destroys blood vessels supplying malignant tumors while sparing the vasculature of normal tissues. Vascular targeting agents like combretastatin attack proliferating blood vessels that already exist, whereas angiogenesis inhibitors generally stop new blood vessels from developing.
In this study, 29 patients with a range of solid tumors, unresponsive to traditional chemotherapy, were treated with a daily intervenous dose of combretastatin for five consecutive days every three weeks. All of the patients were given CT scans before and at the end of the treatment cycle to determine changes in tumor blood supply. Nine patients who were given the highest dose of combretastatin were monitored via MRI. Dr. Stevenson's team found evidence of a decrease in blood flow to the tumor following combretastatin therapy in five of the nine patients who were followed by MRI.
"These early results are promising and suggest that combretastatin may affect tumor blood supply," says Stevenson. "We will continue investigating this drug for its potential benefits in fighting advanced cancers."