Last October, a Massachusetts jury found that Roche's anaemia drug Mircera infringed 11 Amgen patent claims, preventing Roche from launching the drug in the US.

Amgen accused Roche of breaching its patents over Aranesp, a drug that stimulates red blood cell production, and Epogen, a protein that mimics the action of a protein produced by the kidneys to stimulate the production of oxygen-transporting red blood cells.

Switzerland-headquartered Roche counter-claimed that Amgen's patents were invalid and argued that the company had misled the USPTO to obtain them. In April this year, Roche appealed the district court's issuance of a preliminary injunction to the Federal Circuit.

In last week's 150-page opinion, Judge William Young said that he would enter the permanent injunction once the pending appeal has been resolved.

The upcoming appeal marks the first time that the Federal Circuit will consider a challenge to a district court's grant of injunctive relief to a pharmaceutical patentee based on the four-factor test set forth in eBay v MercExchange.

In a release, Amgen's senior vice president and general counsel David Scott said that he was pleased with the ruling, which "reaffirms the infringement and validity of our patents".

Oral arguments in Roche's appeal are scheduled to be heard this Wednesday, October 8.