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June 23, 2008 -- A leukemia drug may help make a clot-busting drug used to treat strokes more effective and safer to use.
Blood clots in the brain cause about 80% of the 15 million strokes that occur each year worldwide. Immediate treatment of these strokes is limited to the use of tissue plasminogen activator (tPA), which works by dissolving clots.
While tPa can reduce potential brain damage associated with stroke, the downside is that it is only given within three hours of the start of a stroke, and it carries the risk of dangerous bleeding in the brain.
But a new study suggests giving the cancer drug Gleevec prior to tPA can extend the time frame during which the clot-busting drugs are effective as well as reduce the risk of bleeding in the brain. So far, the combination has been studied only in mice, but researchers say the findings are promising.
"Our findings may have immediate clinical relevance, and could be applied to find new treatments that will benefit stroke patients," says researcher Daniel Lawrence, PhD, professor of cardiovascular medicine at the University of Michigan Medical School, in a news release.
In the study, published in Nature Medicine, researchers examined the effects of Gleevec on mice with induced strokes.
First, they induced strokes in two groups of mice and gave one group Gleevec an hour after the stroke began.
The results showed mice that received Gleevec experienced less leakage in the brain as a result of the stroke, and 72 hours later the Gleevec-treated mice had 34% less brain damage than the others.
Then the researchers evaluated Gleevec as a pretreatment before clot-busting tPA therapy. Mice were given Gleevec one hour after the stroke began and then a dose of tPA five hours after the onset of the stroke.
Researchers assessed bleeding in the brain by measuring the amount of hemoglobin in the stroke-affected side of the brain. Mice who received Gleevec prior to tPA treatment had significantly less bleeding in the brain area than those who didn't receive pretreatment.
Researchers say this last finding is especially encouraging because stroke diagnosis often takes hours. If these findings are confirmed in humans, Gleevec could be given immediately when a stroke is suspected to extend the window in which tPA may be given.