Aranesp may cause antibody production leading to RBC aplasia and anemia

Darbepoetin (Aranesp) is often given to patients with anemia of chronic disease (e.g. due to ESRD) to stimulate RBC production.

Postmarketting studies showed that Aranesp can induce the development of neutralizing antibodies to erythropoietin. These antibodies suppress RBC production leading to pure red cell aplasia (PRCA) and profound anemia. Other blood cell lines may also be affected resulting in cytopenia.

This side effect of Aranesp use was known for a while now and the new development is that FDA added a warning to the drug label. The "Dear Health Care Professional" letter was sent in November 2005 (pdf).

Any patient who develops a sudden loss of response to Aranesp, anemia and low reticulocyte counts should be evaluated for causative factors. If no cause is found, the patient should be tested for antibodies to erythropoietin and Aranesp therapy should be stopped.

Do the other recombinant human erythropoietins cause PRCA?

Yes, all recombinant erythropoetins can cause PRCA. This is not Aranesp-specific.

How often does PRCA occur with recombinant erythropoietin use?

Antibody-associated PRCA is extremely rare. During the first 10 years of therapy with recombinant human erythropoietin, only three cases of PRCA have been reported. There was a peak in the incidence of PRCA in 2001 and 2002 which was likely due to a change in the formulation of one of the epoetins.

Update 3/28/2007:

FDA added a black box warning to the labels of all currently available Erythropoiesis Stimulating Agents (ESAs). Source: ASN.

References:
FDA Safety Changes: Cipro, Aranesp, Marcaine. Medscape.
Epoetin-Induced Autoimmune Pure Red Cell Aplasia. J Am Soc Nephrol 16: 67-69, 2005
Aranesp® Prescribing Information: Adverse Reactions.
Pure Red-Cell Aplasia and Epoetin Therapy. NEJM, Volume 351:1403-1408, September 30, 2004, Number 14.
Pure Red Cell Aplasia With Anti-Erythropoietin Antibodies Occurs More Commonly With One Formulation of Epoetin Alfa than Another. Medscape.
Pure Red Cell Aplasia. eMedicine.

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