UPDATE 2-US patent appeals court rules on Roche, Amgen fight

(Recasts, adds background, analyst comment)

WASHINGTON, March 19 (Reuters) - A U.S. appeals court that specializes in patent cases handed Roche Holding Ltd (ROG.VX: Quote, Profile, Research) on Wednesday a small win in a fight with Amgen Inc (AMGN.O: Quote, Profile, Research) over EPO anemia drugs, but Amgen won the right to have the lower court decide if the patent was infringed, said court documents.

In a parallel legal fight, Amgen had asked the U.S. District Court in Boston to bar Roche from selling its drug Mircera and was granted a preliminary injunction.

As part of that litigation, Roche said it would pay a 22.5 percent royalty to Amgen, but Amgen has not agreed.

Amgen's shares fell to their lowest level since 2002 on Tuesday after Roche agreed to the royalty payment and the U.S. government cut the rate it pays for Amgen's anemia drug Aranesp.

Amgen's shares, battered over the past year by concerns about the safety of its top-selling anemia drugs Epogen and Aranesp, were down nearly 5 percent on Tuesday and fell another three percent on Wednesday to close at $39.97. A year ago the stock stood at $59.14.

Amgen had asked the International Trade Commission, which hears patent cases over imported products, to bar Roche from importing recombinant human erythropoietin, or EPO, and its derivatives.

The ITC allowed the imports and the U.S. Appeals Court for the Federal Circuit agreed, on the grounds they were legal because they were not for sale but part of an effort to get approval from the Food and Drug Administration.

But the trade commission also said it did not have jurisdiction to judge whether the EPO infringed an Amgen patent because the product was not being sold in the United States.