Biogen Inc. announced Friday that it has begun Phase IIIclinical trials to study hirulog as a potential treatment forunstable angina. The drug is the first proprietary productBiogen has supported by itself to reach a Phase III trial stage.

"It's major product for us," said Amy Seltzer, director ofinvestor relations for Biogen. "You can compare it to heparin,which has a $500 million market worldwide," she said. Heparin,which is also used to treat unstable angina, is currently thetreatment of choice.

Seltzer said hirulog has had a better safety record so far thanheparin. "The problem with heparin is that it doesn't work aswell in arteries as it does in veins," she said. "It's an indirectthrombin inhibitor. Hirulog is a direct thrombin inhibitor."

Seltzer said one of heparin's problems is that it depends on theamount of anti-thrombin 3 in the blood. This level differs inevery patient, so the use of heparin must be administered andmonitored carefully. Since hirulog does not depend on theamount of anti-thrombin 3 in the blood, it is easier to setdosages.

Seltzer said another problem with heparin is that it can causehemorrhaging. "There is bleeding associated with heparin thatwe have not had in our trials so far with hirulog," she said."Heparin has a clinically significant bleeding rate of 6.6 percent.Hirulog has shown no clinically significant bleeding rate."Seltzer also said that Biogen's studies have shown the bodydoes not form antibodies against hirulog. "There is no bleeding,no antibodies formed, no problems -- and it works," Seltzersaid. "We are positioning it as better than other anti-coagulanttherapy."

The Phase III trials will involve two pivotal studies. The firstone, announced Friday, began in May and should be completedby the end of the year, according to Seltzer. It will beconducted using only a few hundred patients. The second,which will begin shortly after the completion of the first trial,will involve 1,000 to 2,000 patients.

"The trials should end in about 12 to 16 months," Seltzer said."Most analysts are predicting the end of 1993 or the beginningof 1994 for filing (with the FDA). I'm comfortable with that."

In addition to the unstable angina indication, Seltzer saidBiogen is discussing with the FDA registration trials usinghirulog, such as the possibility for using hirulog for angioplastyand thrombosis.

-- Steve Payne BioWorld Staff

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