AMGEN FILES PATENT INFRINGEMENT SUIT.

Byline: Ronald Rosenberg The Boston Globe

An expected legal clash between giant Amgen Inc. and Transkaryotic Therapies Inc., a development-stage biotech, erupted Wednesday when Amgen filed a patent infringement suit against Transkaryotic.

The suit, filed in U.S. district court in Boston, casts a legal cloud over whether Transkaryotic will be able to make and sell an anti-anemia drug that would be its first commercial product.

For Thousand Oaks-based Amgen, the issue is protecting its crown jewel: erythropoetin, or EPO, also known by its trade name Epogen. The hormonal drug stimulates red blood cell production in bone marrow to fight anemia. With revenues last year of $1.07 billion, it is the world's best-selling drug and accounts for nearly half of Amgen's $2.2 billion in annual revenue.

Amgen, the world's largest biotech company, filed suit against Transkaryotic and its corporate partner Hoechst Marion Roussel to stop Transkaryotic, of Cambridge, Mass., from producing a substantially comparable version of EPO using an alternative manufacturing process.

Last year, Amgen's shares fell after Transkaryotic announced it would begin testing its own EPO product during the first half of 1997.

The question is whether Transkaryotic's alternative production method for EPO infringes on Amgen's five EPO patents - including one issued two days ago and another last week.

With Hoechst Marion Roussel, one of the world's largest pharmaceutical companies, as its partner, Transkaryotic has the deep financial pockets to battle Amgen. The large German pharmaceutical firm owns 13 percent of Transkaryotic Therapies and is reportedly prepared to invest up to $125 million for a new version of EPO.

Wednesday, Dr. Richard F. Selden, Transkaryotic's founder, chairman and chief executive, declined to comment about the Amgen lawsuit, although he and his company have indicated they expected it.

Wall Street reaction favored Amgen, whose shares rose 1-1/8 to 57, while Transkaryotic shares dropped 1-3/4 to 17-1/4 on Nasdaq.

Transkaryotic's strategy is to develop alternative versions of blockbuster biotech drugs using alternative manufacturing processes. Several companies have developed comparable strategies, such as Aeres-Serono SA of Switzerland, which last year gained U.S. Food and Drug Administration approval for its version of human-growth hormone made in mice. The original bioengineered human growth hormone was developed by Genentech Inc. in bacteria.

Amgen has a combination of product and manufacturing process patents that it plans to enforce. Amgen's EPO is Transkaryotic's ``prime and initial copycat target,'' according to the 21-page Amgen complaint. The suit noted the Cambridge biotech company has increased pilot production in Massachusetts and that Hoechst also has full-scale production capabilities.

Transkaryotic claims that its protein is made in human skin cells instead of through the traditional method of splicing genes into animal or bacteria cells. But the suit maintains that the newly issued Amgen patents now cover human and nonhuman methods of EPO production and that Transkaryotic thus violates Amgen's latest patents.