The FDA approved the first emergency treatment for stroke Tuesdayby expanding use of Genentech Inc.'s clot-dissolving drug, Activase,to patients who get medical attention within three hours of sufferingthe brain-damaging condition.
The approval came less than two weeks after the FDA's Peripheraland Central Nervous System Drugs Advisory Committeeunanimously recommended marketing Activase, or tPA, under strictguidelines for acute ischemic stroke, which accounts for about 80percent of the 500,000 cases each year in the U.S.
The other 20 percent of strokes are caused by bleeding, not clotsshutting off the flow of blood to the brain, and those patients wouldnot be eligible for Activase.
Restricting use of the drug to within three hours was based on datashowing intracerebral bleeding, a side effect of Activase, becomesmore of a problem the longer it takes to administer the treatment.Even when patients get Activase in three hours, a National Institutesof Health (NIH) study showed 6.4 percent of them experiencedhemorrhages within 36 hours compared with .6 percent in the placebogroup.
However, that five-year NIH trial with 624 patients found thosetreated with Activase within the time limit were 30 percent morelikely to achieve complete or near complete recovery when evaluatedthree months after their strokes. An earlier study in Europedemonstrated the drug, when administered within six hours, did notachieve clinical benefits.
NIH officials said Tuesday findings from their study demonstrated "asignificant benefit to treatment despite an increased risk of brainhemorrhage." Stroke is the third leading cause of death in the U.S.and the leading cause of adult disability.
NIH officials said the trials showed the importance of treatingischemic stroke as an emergency and they urged implementation ofeducational campaigns for health care professionals and the public torecognize the signs of stroke and seek medical care immediately.
In addition to administering Activase within three hours of onset of astroke, another limiting factor for use of the drug is evidence ofbleeding, which can be detected with a computed tomography scan.
Activase, which is marketed by Genentech, of South San Francisco,for acute heart attack and pulmonary embolism, sells for $2,000 perdose and is the company's biggest money maker, generating revenuesof $300 million in 1995. The drug captures 75 percent of allthrombolytic sales in the U.S.
Wall Street analysts have estimated modest gains in sales forActivase under the expanded label because of the three-hour timelimit on administering the drug.
However, Toni Claudio, analyst with Smith Barney in New York,said approval of the first-ever treatment for stroke is "very exciting."She noted Genentech is conducting an additional trial to determinethe benefit of treating patients between three and five hours afteronset of the condition.
Claudio also suggested Activase may be effective in combinationwith other drugs, which are being developed to prevent cell damagefrom ischemic stroke but have difficulty getting into the brainbecause of the blocked arteries.
Genentech's stock (NYSE:GNE) closed Tuesday down 12 cents to$53.12. Genentech is about 70 percent owned by Roche HoldingLtd., of Basel, Switzerland. n
-- Charles Craig
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