Genentech Inc. said Friday that it filed with the Food and DrugAdministration a product license application (PLA) to extendapproval of Activase tissue plasminogen activator (t-PA) todissolving blood clots caused by peripheral arterial occlusivedisease.

The clot-buster received FDA approval in late 1987 for treatingheart attacks and pulmonary embolisms, and later for treatingobstructions in lung arteries. Its sales are running at about$200 million a year.

Peripheral arterial occlusive (PAO) disease refers to clots thatprevent blood flow to the extremities, usually the legs. About180,000 patients are diagnosed annually with PAO in theUnited States. It is usually treated with surgery, although up toone-sixth of PAO patients are treated with urokinase orstreptokinase, said Genentech spokesman Jack Murphy.

The FDA has not yet approved a thrombolytic for the PAOindication. Genentech, of South San Francisco, Calif., proposesadministering Activase through a catheter to the blockedartery. Clinical trial results were encouraging, especially intreating persistent blood clots, Murphy said.

Without offering a specific forecast, Genentech (NYSE:GNE)anticipates healthy sales of Activase for PAO. However, Murphyacknowledged the need to educate doctors about the benefits ofthe drug.

As a heart attack treatment, Activase faces less-expensiverivals in streptokinase and Eminase thrombolytic drugs. --Carol Talkington Verser, Ph.D.

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