Bat Saliva-Based Stroke Drug Disappoint...( But the study's design may be to blam...),Health

But the study's design may be to blame for desmoteplase's poor showing, researchers say

THURSDAY, Dec. 18 (HealthDay News) -- An experimental clot-busting drug derived from the saliva of the vampire bat has failed to reduce stroke damage in a major trial.

But hope for the drug, called desmoteplase, remains alive, experts say, because the study may not have been large enough to provide clear results.

"The sample size was underpowered to detect any benefit," said study co-author Dr. Anthony J. Furlan, chairman of neurology at Case Western Reserve University, in Cleveland. "The simplest answer is that stroke is an extremely heterogeneous condition, and it is difficult to predict what the outcomes will be from a smaller size population."

Two earlier and smaller studies showed a benefit when desmoteplase was given intravenously to reopen brain arteries blocked by clots. But there was no significant difference in outcome in the latest trial, called DIAS-2, between stroke victims given desmoteplase and those who got a placebo, said a report to be published online on Dec. 17 in The Lancet Neurology.

But there remains vigorous debate about the best method to use in selecting those stroke patients who will be treated in the next trial, which is in the planning stage, Furlan added.

Desmoteplase was originally spotted in the saliva of the vampire bat, which uses the chemical to keep its victims' blood flowing freely, so it can suck a full meal.

The drug is contending to replace tissue plasminogen activator (tPA), the only current treatment for ischemic strokes, which are caused by blockage of a blood vessel. Most strokes are ischemic strokes; tPA is given by intravenous injection and works quickly to dissolve clots.

"But tPA must be given within three hours of a stroke, so only a small percentage of patients can get the treatment," Furlan noted. "We hope to triple that window to
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