US regulators have given the green light to Roche's new anaemia drug Mircera, but no launch across the Atlantic is likely for some time as the Swiss firm is embroiled in a legal dispute it is losing against rival Amgen.

The US Food and Drug Administration has approved Mircera (methoxy polyethylene glycol-epoetin beta) for the treatment of anaemia associated with chronic renal failure in adults, making it the only agency-approved erythropoiesis-stimulating agent to provide correction of the disease with once-every-two-week dosing. It also offers the added convenience of storage at room temperature for extended periods when necessary, Roche added.

Nevertheless this may not be much use in the near future as Roche cannot sell Mircera in the USA yet. The problem is that a jury in a district court in Boston last month ruled that the drug infringes on 11 Amgen erythropoietin (EPO) patent claims. The decision was a significant victory for Amgen which was facing competition for its anaemia drugs Epogen (epoetin alfa) and Aranesp (darbepoetin alfa) and the US biotechnology major is seeking an injunction on Roche’s product. The hearing is scheduled to begin later today.

How that case develops will determine if US patients can gain access to Mircera, though the Boston decision suggests that Amgen has the upper hand. Elsewhere, the drug has already been launched in Austria, Sweden, Germany, the UK and Norway.

George Abercrombie, chief executive of Roche in the USA, said the firm was pleased that the approved FDA label “reflects the differentiating characteristics of Mircera", which the Swiss firm says has the longest half-life of all FDA-approved ESAs, up to six times longer than Aranesp and up to 20 times longer than Epogen. He noted that in Europe, thousands of patients “are receiving effective, predictable and convenient anaemia treatment” with Roche’s drug, “and we are hopeful that patients and healthcare providers in the USA will be able to have access to Mircera as soon as possible, in a responsible and legal manner."