Leukemia Medication May Be Beneficial to Stroke Patients

A powerful medication that is highly effective in the fight against leukemia may boost the effectiveness and reduce complications of a common treatment used for stroke patients. According to an international team of researchers, studies in mice have shown that giving Gleevec (imatinib) significantly reduced bleeding in the brain caused by the emergency clot-busting drug called tPA (tissue plasminogen activator) and also appeared to extend the time window in which tPA could be given.

tPA has been the most effective emergency treatment for the most common kind of stroke for over a decade but can cause dangerous bleeding in the brain. In addition, the brain-saving power of tPA deteriorates quickly following the third hour after a stroke. Gleevec, made by Novartis AG and known as a wonder drug against cancers like chronic myelogenous leukemia (CML) will be tested for potentially limiting the side effects of tPA and boosting the effectiveness of the drug.

According to the World Health Organization ischemic strokes account for 80 percent of the 15 million strokes that occur each year worldwide. An ischemic stroke is a type of stroke caused when a blood clot obstructs blood flow to the brain. tPA is used to dissolve these blood clots within the first three hours of a stroke with significant success in reducing death and disability.

In actuality, less than 3 percent of patients with ischemic stroke receive tPA because the narrow safety window has often passed by the time a stroke patient reaches a hospital and is diagnosed. And, because the drug causes bleeding, it can't be used for other types of strokes such as an intracerebral hemorrhage, which occurs when a blood vessel in the head ruptures.

Daniel Lawrence of the University of Michigan Medical School who worked with researchers from the Karolinska Institute in Stockholm, Sweden explained, "You potentially could reduce the amount of side effects associated with tPA and increase the population that could receive it." The findings of the study were published in the journal Nature Medicine.

According to Lawrence, the study offered a better understanding of why tPA causes bleeding. When tPA trickles into the brain through stroke-damaged vessels, it seems to act on a protein involved in blood vessel formation called PDGF-CC and the PDGF-alpha receptor that it binds to. This weakens the mechanism that protects the brain from toxins in the blood and makes blood vessels dangerously leaky. Gleevec blocks the PDGF-alpha receptor and appears to counteract the effect.

The studies suggest that Gleevec could help prevent the blood vessel leakage associated with tPA and could also extend the time window in which it can be used. Lawrence said that if the findings are confirmed in humans it could give patients and doctors more time and that "it could have a huge benefit."

The first human trial will soon begin in Sweden by physicians at the Karolinska Institute Hospital in Stockholm. The trial will include 60 people to be treated within hours after they suffer strokes. Some people will be given Gleevec within three hours of the stroke in addition to tPA treatment while others whose treatment started later some reason will be given Gleevec in addition to tPA after the standard three-hour period. The results will be compared to similar stroke patients who received standard treatment. Results of the study should be available within a year.