Biogen Inc. on Tuesday reported Phase II clinical trial results ofHirulog, its anti-coagulant for treating unstable angina, at the65th Annual American Heart Association Meeting in NewOrleans.

In short, the researchers have found that Hirulog is safe,effective, and easy to dose. Unstable angina is a severecardiovascular condition caused by a transient blockage of acoronary artery as a result of thrombosis. It can lead to a heartattack. The majority of people affected by this condition arecandidates for anti-coagulant therapy.

Hirulog, a 20-amino acid compound based on hirudin, thenatural anti-coagulating enzyme secreted by leeches, is aspecific inhibitor of free and clot-bound thrombin (a proteolyticenzyme that facilitates blood clotting). It is being positioned asa replacement therapy for heparin, currently the anti-coagulant drug of choice.

Together with researchers at hospitals and medical centers --including the Montreal Heart Institute and Boston's Brighamand Women's Hospital -- Biogen's John Maraganore andassociates studied Hirulog's anti-coagulating abilities in patientswith unstable angina, hip or knee surgery patients who were atrisk for developing venous thrombosis (blood clots), andpatients undergoing balloon angioplasty (percutaneoustransluminal coronary angioplasty).

In all cases, the trial data indicated that Hirulog is safe andeffective. There were no serious bleeding complications, and athigh doses, the compound appears to be better than currenttreatments in reducing the incidence of venous thrombosis injoint surgery and the incidence of abrupt vessel closure inangioplasties. Compared with heparin, Hirulog was also betterat preventing patients with unstable angina from progressingto intractable angina, coronary thrombosis or myocardialinfarction. Importantly, dosing regimens of Hirulog proved tobe predictable -- something that apparently doesn't alwayshold for heparin.

Given that the market for heparin as a generic is already $400million worldwide, the potential for any compound that couldsuccessfully replace it is enormous. But Hirulog isn't the onlyanti-thrombotic in development. "Ciba-Geigy has a hirudinproduct in the same stage of development as Biogen's Hirulog,"said Wole Fayemi, an analyst with Hambrecht & Quist, "andCentocor's anti-platelet product CentoRx is also in advanceddevelopment." Another potential competitor is Integrelin, aglycoprotein anti-thrombotic being developed by CorTherapeutics Inc. of South San Francisco, Calif.

About 1 million people suffer from unstable angina every yearin the U.S. Another 300,000 to 400,000 require balloonangioplasty every year, and there are about 2 million cases ofdeep vein thrombosis, 500,00 to 750,000 of which requirehospitalization, Fayemi said. Although the latter is the biggestpotential market, Fayemi said, it's not the one where Hirulog isapt to gain a significant share.

"In deep vein thrombosis, it doesn't seem to be much betterthan the new, lower-molecular-weight heparins," he said. Forarterial indications, however, Fayemi said Hirulog has realadvantages.

Amy Berler, an analyst with Alex. Brown & Sons in New York,prefers to wait for Hirulog's Phase III trial data before placingher bets as to whether "forms of hirudin may both displaceheparin and do so at an attractive price." Berler told BioWorldthat heparin is already very inexpensive. "It's a very toughmarket."

Biogen stock (NASDAQ:BGEN) was down $2 a share to $42.

-- Jennifer Van Brunt Senior Editor

(c) 1997 American Health Consultants. All rights reserved.

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