Drugs Xagena
Amgen has informed Health Care Professionals that sections of the product prescribing information for Aranesp ( Darbepoetin alfa ) have been updated regarding the fact that pure red cell aplasia ( PRCA ) and severe anemia, with or without other cytopenias, associated with neutralizing
antibodies to erythropoietin have been reported in patients treated with Aranesp.
This has been reported predominantly in patients with CRF ( chronic renal failure ) receiving Aranesp by subcutaneous administration.
Any patient who develops a sudden loss of response to Aranesp, accompanied by severe anemia and low reticulocyte count, should be evaluated for the etiology of loss of effect, including the presence of neutralizing antibodies to erythropoietin.
If anti-erythropoietin antibody-associated anemia is suspected,withhold Aranesp and other erythropoietic proteins.
Aranesp should be permanently discontinued in patient s with antibody-mediated anemia.
Patients should not be switched to other erythropoietic proteins as antibodies may cross-react.
In clinical studies,the percentage of patients with antibodies to Aranesp was examined
using the BIAcore assay.
Sera from 1501 CRF patients and 1159 cancer patients were tested.
At baseline,prior to Aranesp treatment, binding antibodies were detected in 59 ( 4% )
of CRF patients and 36 ( 3% )of cancer patients.
While receiving Aranesp therapy ( range 22-177 weeks ), a follow-up sample was taken.
One additional CRF patient and eight additional cancer patients developed antibodies capable of binding Aranesp
None of the patients had antibodies capable of neutralizing the activity of Aranesp or endogenous
erythropoietin at baseline or at end of study.
No clinical sequelae consistent with PRCA were associated with the presence of these antibodies.
Source: FDA, 2005
XagenaMediicne_2005
