Stroke victims could benefit from bat-spit protein

Many years ago, scientists observed that when such bats bit other animals, they would cause their victims to bleed to death.

VANCOUVER — Hospitals across Canada are helping to test whether a genetically engineered drug made from a protein in vampire bat saliva can treat strokes.
It's part of an international trial taking place in nearly 100 nations.
The drug company-sponsored trial is investigating whether the experimental treatment, Desmoteplase, is safe and effective at breaking up brain clots in patients who arrive at hospital three to nine hours after the onset of symptoms.
Hospitals in Vancouver, Calgary, Edmonton, Toronto, Halifax are taking part in the trial.
The trial is randomized, double-blinded and placebo controlled, which means that patients who enrol have an equal chance of getting the drug or a placebo. Patients consenting to the trial will not know if they received the drug or the placebo.
Dr. Ashfaq Shuaib, the University of Alberta hospital neurologist who is the national co-ordinating investigator of the trial, said this week the intravenous drug originated with vampire bats native to Mexico and South America.
Many years ago, scientists observed that when such bats bit other animals, they would cause their victims to bleed to death.
He said that led to speculation that a drug made from their saliva might be effective at breaking up blood clots causing heart attacks or strokes.
At present, only one clot-busting drug — alteplase, also known as TPA — is approved for acute ischemic stroke patients.
Ischemi stroke is defined as death of brain tissue due to an inadequate supply of blood and oxygen to the brain, which results from blockage of an artery.
TPA can only be administered intravenously if patients get to hospital within 4 1/2 hours of the onset of symptoms.
People living in rural or remote regions often don't have access to such treatment, since it must be given in hospitals with stroke specialists and CT or MRI-imaging equipment to detect blood clots. TPA carries about a five per cent risk of inducing brain bleeding, Shuaib said.
Due to those limitations, only about three per cent of all stroke patients end up being treated with TPA.
At the International Stroke Conference a few months ago in San Antonio, Tex., H. Lundbeck, the Denmark-based drug company involved in the trials, said about 800 patients around the world would be enrolled in two trials.
The National Institutes of Health clinical trials website, an American registry of trials, estimates the trials will be completed by September 2011.
In a 2007 study in the journal Stroke, European researchers called desmoteplase a "promising alternative" to TPA.
The study noted pre-clinical evidence showed the experimental drug may offer benefits over TPA, including a reduced risk of brain hemorrhage, improved safety and a longer treatment window of opportunity.