Roche’s hopes to get its new anaemia treatment Mircera onto the market have been hampered by US regulators who have only issued an approvable letter for the compound, amid fears about the safety of erythropoiesis-stimulating agents.

The Switzerland-based group did not reveal the further information that the US Food and Drug Administration has requested about Mircera (continuous erythropoietin receptor activator), which it filed with the agency last April seeking approval for use of the treatment in anaemia associated with chronic kidney disease in patients on or not on dialysis. However the firm did say that it would not have to conduct additional clinical trials before approval and George Abercrombie, chief executive of Roche’s unit, said “we are confident that Mircera will be approved”.

The news of the letter comes in the wake of an FDA oncology advisory committee’s recommendation for further strengthening of the warning labels on Amgen's ESAs, Aranesp (darbepoetin alfa) and Epogen (epoetin alfa), as well as Johnson & Johnson's Procrit (also epoetin alfa). A second panel is expected to meet in the next few months to review ESAs (but not Procrit) for patients with kidney disease and Mr Abercrombie said that “we understand and support the FDA's initiative to convene an advisory panel to review the use of anaemia agents in the renal setting".

If Mircera does get the go-ahead, it would challenge the monopoly that Amgen’s products enjoy in the market to treat anaemia in people undergoing kidney dialysis. Furthermore, Roche believes that its drug has an advantage in that could be given as infrequently as once every four weeks, while the dosing regimen for Epogen and Procrit can be up to three times a week.

However, getting FDA approval may not be enough to get Mircera onto the market, as Roche and Amgen have been involved in a bitter patent battle, the latest round of which is due to come to court in September. Amgen believes that the drug contravenes its patent armoury and victory for the US biotechnology firm could leave Mircera in limbo.