Vampires Go to Bat for Stroke Treatment
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Vampires aren’t usually cast in the role of saviors, but stroke experts are hoping a blood thinner that mimics a chemical in vampire saliva will help save brain cells in stroke patients.
University of Wisconsin School of Medicine and Public Health is one of several centers worldwide currently enrolling patients in a large new clinical trial of desmoteplase, a drug based on an enzyme in vampire bat saliva. The enzyme thins the blood of the bats’ victims to prevent it from clotting as the bats feed. Its name comes from the scientific name for vampire bats, Desmodus Rotundus.
Early trials of the drug shows that it may be able to extend the window of medical treatment up to nine hours after the onset of a stroke. The current gold standard for stroke treatment, alteplase, has been shown to be effective only up to four and a half hours, and carries a risk of serious bleeding in a small percentage of patients.
After the initial promising findings, desmoteplase showed disappointing results in the second round of trials in which the entire group of patients taking it did only as well as those who got the placebo. But Dr. Matt Jensen, a UW Health stroke neurologist, says that a more careful look at the data suggest that there may be some patients who are better suited for the drug.
“We think that there is a group of patients who may benefit," he says. “With more advanced imaging, we hope to be able to identify people who are more likely to respond to the drug.”
In an ischemic stroke, a blood clot blocks an artery to part of the brain, and over several hours without oxygenated blood, the brain cells begin to die. But Jensen explains that some patients have better circulation to the brain that allows enough blood to get around the blockage through other arteries. This can allow the brain cells to survive longer until the blood clot is broken up, and good blood flow is restored. Physicians at UW Hospital will use advanced imaging techniques using MRI and CT to find stroke patients who are better candidates for later treatments.
Jensen says that the physicians of the UW Health Comprehensive Stroke Program take calls from around the state from doctors looking to help patients who arrive too late for the standard treatments.
“As part of this trial, we will be able to treat certain people up to nine hours after the onset of stroke symptoms," he said. “With ground and helicopter transfers we can get people here quickly and potentially offer them a chance for this investigational treatment.”
