A federal appeals court ruled Tuesday that Roche Holding AG's (RHHBY) Mircera anemia treatment infringes some patent claims held by Amgen Inc. (AMGN) and it refused to lift a permanent injunction barring Roche from selling Mircera in the United States.

A federal judge in Boston entered the injunction last fall, which barred Roche from competing in the U.S. with Amgen's anemia drugs Aranesp and Epogen.

Amgen's two anemia drugs brought the California-based biotechnology company $4.1 billion in U.S. revenue for 2008, more than 35% of the drug maker's U.S. product sales.

The U.S. Court of Appeals for the Federal Circuit issued a mixed 81-page ruling Tuesday that sided with each of the companies on some portions of the case.

But despite reversing the trial judge on several issues, the appeals court affirmed that Roche's drug did infringe on some of Amgen's patent claims.

"We do not disturb the court's injunction," the appeals court wrote.

It sent the case back for further proceedings and said the trial court was "free to reconsider the scope of its permanent injunction if it wishes."

Roche spokesman Christopher Vancheri said the company is considering its options.

"We obviously are disappointed the court did not find in Roche's favor on all of the matters," he said.

An Amgen spokesman did not respond to requests for comment.

The case is Amgen Inc. v. F. Hoffmann-La Roche Ltd., 2009-1020.

-By Brent Kendall, Dow Jones Newswires; 202-862-9222; brent.kendall@dowjones.com