UPDATE 2-Amgen says court backs one patent claim vs Roche

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By Lisa Baertlein

LOS ANGELES, Aug 28 (Reuters) - Amgen Inc said on Tuesday a federal court has ruled a Roche Holding AG product infringes an Amgen anemia drug patent, sending the shares of the world's biggest biotechnology company up more than 2 percent.

The Amgen (AMGN.O: Quote, Profile, Research, Stock Buzz) victory is for a composition of matter patent, which analysts said is often the most important because it covers chemical compounds and is considered an effective tool for blocking rival drugs or generics.

Amgen's anemia franchise, which had sales of $6.6 billion last year, has been under siege due to safety concerns and a pullback of coverage by the U.S. agency that oversees Medicare and Medicaid.

The company, based in Thousand Oaks, California, has long battled to keep Roche's (ROG.VX: Quote, Profile, Research, Stock Buzz) Mircera, which is approved in the European Union, out of the market in the United States.

If approved, Mircera would compete with Amgen blockbusters Epogen and Aranesp and Johnson & Johnson's (JNJ.N: Quote, Profile, Research, Stock Buzz) Procrit.

Roche has argued its drug is different, claiming Mircera is longer lasting than other available anemia drugs.