Six years after the European Patent Office grantedGenentech Inc. protection for its blood clot dissolver,tPA, the company Tuesday won a final appeal of itsintellectual property rights from three companies.

Officials of South San Francisco-based Genentech saidthe European Patent Office upheld the company's "broadclaims" related to preparation of tPA, rejecting challengesfrom Boehringer Mannheim GmbH, of Mannheim,Germany, Celltech Group plc, of Slough, England, andGlaxo Wellcome plc, of London.

Boehringer Ingleheim GmbH, of Ingleheim, Germany,markets tPA as Atleplase in Europe under an exclusivelicensing agreement with Genentech, which sells the clotbuster in the U.S. as Activase. The drug is marketed fortreatment of acute heart attacks and in the U.S. Activasecaptures 75 percent of the thrombolytic market.

Genentech was granted a European patent for tPA in1989. In June 1992, the European Patent Office ruledagainst seven drug companies that opposed the patent.Boehringer Mannheim, Celltech and the WellcomeFoundation Ltd. appealed rejection of their opposition.Earlier this year the Wellcome Foundation merged itssubsidiary, Burroughs Wellcome Co., of ResearchTriangle Park, N.C., with London-based Glaxo Holdingsplc forming Glaxo Wellcome.

The ruling granted Tuesday for Genentech ends theEuropean patent battle, company officials said, addingthat any firm developing thrombolytics may infringeGenentech's intellectual property protections.

In a prepared statement, Genentech officials said, "Thepatent claims cover the preparation of a tPA protein byexpression in a recombinant host organism and includesrecombinant human tPA, alleles and derivatives."

Of the three challengers, Boehringer Mannheim is theonly one with a thrombolytic compound in clinicaldevelopment. In March 1995, the company launched aPhase III study using its form of tPA, reteplase (rPA) in ahead-to-head evaluation against tPA for treatment ofheart attacks. Boehringer Mannheim is a subsidiary ofBermuda-based Corange Ltd.

In July 1993, Genentech won a permanent injunction inthe U.S. preventing Burroughs Wellcome from selling itsversion of tPA, called duteplase, until 2005 whenGenentech's U.S. patent protection expires. Wellcomesubsequently discontinued development of duteplase.

Although Celltech challenged the European patent, thecompany apparently never initiated clinical developmentof a thrombolytic agent.

In the U.S., sales for tPA were $281 million in 1994 and$225 million through the first three quarters of 1995.Sales figures for tPA in Europe were unavailable.

Genentech's stock (NYSE:GNE) closed Tuesday at$51.87, up 12 cents. The company is 70 percent owned byBasel, Switzerland-based Roche Holdings Ltd. n

-- Charles Craig

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