Antibody-mediated acquired pure red cell aplasia (PRCA) after treatment with darbepoetin

Recombinant erythropoietin (EPO) is used successfully as treatment for anaemia in chronic kidney disease (CKD), to maintain stable haemoglobin levels, avoiding the need for multiple transfusions. From 1998, epoetin formulations, in particular epoetin alfa (Eprex®, Ortho Biologics LLC), have been associated with a substantial increase in the incidence of antibody (Ab)-mediated pure red cell aplasia (PRCA) [ 1 ]. PRCA is a rare immunopathological disorder characterized by a severe reticulocytopenia, the absence of marrow erythroid precursors, normal granulocytic and megakaryocytic precursors, and the identification of circulating antibodies against EPO [ 2 ]. Patients typically develop an abrupt onset of severe transfusion-dependent anaemia. Consequently, EPO must be withdrawn and therapy initiated to decrease the production of the anti-EPO antibodies. Darbepoetin alfa (Aranesp®, Amgen Inc., CA) is a second generation erythropoiesis stimulating agent with two extra carbohydrate chains and eight extra sialic acid residues as compared with epoetin alfa. It is suggested that the modifications to this molecule may make it more resistant to antibody development. There is only a single published case report of PRCA related to the exclusive use of darbepoetin alfa [ 3 ]; however, communication with Amgen Australia Pty Ltd indicate about four cases on their database. In a sole published case of PRCA due to darbepoetin alfa, the patient did not respond to treatment with steroids alone, intravenous immunoglobulin, cyclosporin or combination prednisolone and cyclophosphamide [ 3 ].