The patent battle between Amgen and Roche over the latter’s anaemia drug Mircera is likely to go on for quite a while yet as a judge has delayed making a decision on whether the Swiss company should be allowed to launch the treatment for patients suffering from kidney disease in the USA.

US District Court Judge William Young says he will delay making a decision on whether Amgen should be granted a permanent injunction to block the sale of Roche's anaemia drug Mircera (methoxy polyethylene glycol-epoetin beta), in order to seek an opinion of a third party. The latter will compare dosing and pricing information between Mircera and Amgen's own erythropoiesis-stimulating agents Epogen (epoetin alfa) and Aranesp (darbepoetin alfa).

Both firms have 15 days to submit a list of potential candidates, and the appointed expert will then have another 60 days to make the requested findings.

Last October, a jury in a US district court in Boston agreed that Mircera does infringe on 11 of Amgen erythropoietin patent claims, but judge William Young said last month that 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.

Explaining the delay, Judge Young said that he "continues to grapple with complex issues related to Amgen's request" for a permanent injunction and has therefore ordered the appointment of a "special master" to make recommendations regarding price parity and dosage. Mircera was approved by US regulators back in November last year, but the company has been unable to launch it there because of the ongoing court battle but getting the green light could have a very damaging effect on the sales of Amgen’s ESAs.