Amgen Inc. is once again facing legal claims against its patent onrecombinant human erythropoietin (EPO). This time the challengecomes from Elanex Pharmaceuticals Inc., a privately held companybased in Bothell, Wash., that markets its own version of EPO incountries outside the U.S.

Amgen (NASDAQ:AMGN) of Thousand Oaks, Calif., filed suit againstElanex and its licensees on Oct. 26, 1993, in Seattle District Court,claiming that Elanex was violating Amgen's U.S. EPO patent byexporting host cells necessary for the production of the recombinanthormone. Amgen's patent on EPO, used to treat anemia associatedwith renal disease, expires Oct. 27, 2004.

In a Dec. 16, 1993, answer and counterclaim, Elanex stated that itscurrent operations do not infringe the Amgen patent, and thatAmgen's EPO patent is invalid. Although Elanex has not yet filed itsformal arguments against Amgen, the company stated that it willoppose Amgen's patent on the grounds that the two EPO technologiesand EPO products are distinctly different.

In March 1991 the U.S. Court of Appeals for the Federal Circuit ruledthat Amgen's patent was valid and enforceable, and was infringed byGenetics Institute's EPO patent.

According to an Elanex document describing its current patentlitigation strategy, the company believes the 1991 decision in Amgenv. Chugai Pharmaceutical Co. Ltd. (GI's marketing partner) restrictsAmgen's U.S. patent to cover "only those variant forms of EPO thatwere actually taught in the patent." GI lost its challenge to Amgen'sEPO business because GI was producing the same EPO as Amgen andnot an analog, the document states.

"There are strong arguments for narrowing the scope of coverage ofAmgen's patent," it continues. "This is necessarily so because Elanexcame along with a superior variant EPO which was nevercontemplated nor taught in the Amgen patent. Our EPO is the casethat demonstrates that the Amgen patent is overly broad."

Elanex's director of international operations, Gregory Barker, toldBioWorld that Elanex's EPO is derived from baby hamster kidneycells, while Amgen's comes from Chinese hamster ovary cells. He alsosaid Elanex's product differs from Amgen's in molecular weight andprotein structure, and is taken from a different gene fragment.Elanex's strategy document further states that it "can prove thatElanex EPO is both structurally and chemically different from AmgenEPO. It is more potent and has less side effects than Amgen EPO."

Elanex's December 16 counterclaim also charges that Amgen "agreedthat so long as Elanex engaged in EPO activities outside of the (U.S.),neither Amgen nor its licensees would take any action to interferewith Elanex's non-USA activities."

Elanex announced last week that will seek to market the drug in theU.S. if it can gain a favorable court decision. The company hasretained Northwest Capital Inc. to pursue licensing agreements withU.S. pharmaceutical companies. Elanex's largest current market forEPO is in India; the company also sells its product or has licensingagreements with companies in Argentina, South Africa, Korea,Germany and several Latin American countries.

Elanex will also dispute Amgen's infringement claim, arguing that itslicensees are in accordance with the patent laws of their respectivecountries and that its own domestic activities do not constituteinfringement.

Amgen would not comment on the litigation.

Elanex also is currently opposing European patents to EPO held byAmgen and GI. Elanex, like the other two companies, holds a patentto EPO granted by the European Patent Office. The company also haspatents for its EPO product in Australia, Portugal, Sri Lanka andSwitzerland. Elanex has applied for patents in Brazil, Canada, China,Denmark, Finland, Japan, Mexico, Norway, the Philippines and theU.S.

In Europe, the company has mapped out several potential litigationstrategies. With the European Patent Office, the strategy documentstates, Elanex can only seek to have Amgen's "very broad" patentinvalidated. The company is considering several different courses inindividual European countries, however. "We can move to have theAmgen patent revoked or restricted so that our patents co-exist," thedocument states. Alternatively, it continues, Elanex could seekcompulsory licensing in countries where Amgen is unwilling to enterinto voluntary licensing agreements or "we can prove that our EPO isnoninfringing," it concludes.

Elanex was founded in 1984. The company's only product is itsrecombinant human EPO, which it licensed from the University ofWashington in the mid-1980s.

-- Karl A. Thiel Associate Editor

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