Amgen’s anaemia drug Aranesp® has been dealt a further blow after it was confirmed that full results from a phase III clinical study showed a higher mortality rate in cancer patients receiving the drug.
As reported in January, Aranesp (darbepoetin alfa) failed to reduce the number of red blood cell transfusions in cancer patients not receiving chemotherapy or radiotherapy. And, although the adverse event rate was similar between the groups, more patient deaths were recorded in the Aranesp arm: 48.5% versus 46% in those taking a placebo.
Although researcher John Glaspy commented that there was “no clear explanation for the increase of deaths in the Aranesp group”, media reports say it has been suggested that the Aranesp patients might have been more ill at the start of the trial than patients in the placebo group.
However, Reuters reports that Amgen will no longer file the drug for anaemia of cancer in the USA, because the findings suggest the benefits of taking Aranesp do not outweigh the risks in patients with unexplained anaemia and active cancer.
This is not the only time the safety of erythropoiesis-stimulating agents has been put in the spotlight. In March, US regulators requested that new safety and dosage information be added to the labels of Amgen’s Aranesp and Epogen® (epoetin alfa) and Johnson & Johnson’s Procrit® (epoetin alfa).
The new boxed warnings advise doctors to monitor red blood cell levels and to adjust the dose to maintain the lowest haemoglobin level necessary to avoid the need for blood transfusions, and doctors and patients are being warned to carefully weigh the risks of these products against transfusion risks.
At the time, the US Food and Drug Adminstration said it acted because recent studies had described “an increased risk of death, blood clots, strokes, and heart attacks in patients with chronic kidney failure when ESAs were given at higher than recommended doses”. Furthermore, other findings revealed more rapid tumour growth among patients with head and neck cancer who received these higher doses.
Aranesp, which is approved to treat anaemia associated with chronic renal failure, is currently Amgen’s number one drug, raking in sales of US$1.11bn in the fourth quarter of 2006 alone.