The battle between Roche and Amgen over the former’s bid to launch Mircera has taken a fresh turn with the news that the Swiss firm is appealing against a preliminary court injunction that prevents US sales of the anemia drug.

Roche’s move comes a fortnight after a US district court judge delayed making a decision on whether Amgen should be granted a permanent injunction to block the sale of Mircera (methoxy polyethylene glycol-epoetin beta). Judge William Young is seeking the opinion of a third party who will compare dosing and pricing information between Mircera and Amgen's own erythropoiesis-stimulating agents Epogen (epoetin alfa) and Aranesp (darbepoetin alfa).

Amgen has asked the judge to permanently bar sales of the Roche drug, based on a decision last October by a jury in a US district court in Boston which agreed that Mircera does infringe on 11 of Amgen erythropoietin patent claims. However in February, Judge Young said he will consider allowing it onto the market if Roche pays a higher royalty rate on US sales of the product (22.5%) and agrees not to price it higher than Amgen’s drugs. The Swiss firm has agreed to these terms.

Now Roche says that “the judge in the federal court encouraged Roche to appeal” and it plans to “vigorously pursue this appeal”. The Basel-based company says it maintains its position that “all of Amgen’s patents… asserted against Roche are invalid and not infringed”.

Amgen is not budging for the moment, however, and said that “aa permanent injunction is the appropriate remedy in this case. We look forward to arguing the case for protection of intellectual property against a proven infringer in the appellate court”. The US biotechnology giant went on to claim that “rewarding theft of intellectual property discourages investment in developing innovative treatments for unmet medical needs”.