Brief communication: Successful treatment of pure red-cell aplasia with an anti-interleukin-2 receptor antibody (daclizumab).
BACKGROUND
Pure red-cell aplasia (PRCA) is a rare hematologic disease characterized by anemia, reticulocytopenia, and absence of bone marrow erythroid precursors. Most patients respond to some form of immunosuppressive treatment, but few prospective clinical trials have been performed.


OBJECTIVE
To examine the efficacy of a humanized monoclonal antibody to the interleukin-2 receptor (daclizumab) for treating PRCA.


METHODS
Pilot study.


METHODS
Federal government research hospital.


METHODS
15 patients with idiopathic PRCA.


METHODS
Daclizumab, 1 mg/kg of body weight, every 2 weeks for a total of 5 infusions. Pure red-cell aplasia was defined as transfusion-dependent anemia with a reticulocyte count of 60 x 10(9) cells/L or less and bone marrow showing absent or diminished erythroid precursors.


METHODS
Response to therapy was assessed by transfusion independence, increments in reticulocyte count, and nontransfused hemoglobin.


RESULTS
Daclizumab had little toxicity. Of the 15 patients, 6 patients (40%) responded to treatment. All responders became transfusion-independent and achieved normal or near-normal hemoglobin values and normal reticulocyte counts.


CONCLUSIONS
The study was unblinded, and the number of patients was too small to assess drug safety reliably.


CONCLUSIONS
Daclizumab seems safe. Its efficacy in this pilot protocol suggests that expanded study in PRCA and other bone marrow failure syndromes is warranted.
Sloand
Elaine M
EM
Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. sloande@nih.gov
Scheinberg
Phillip
P
Maciejewski
Jaroslaw
J
Young
Neal S
NS
D000293:Adolescent; D000368:Aged; D000911:Antibodies, Monoclonal / Q000009:adverse effects* / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D002648:Child; D000077561:Daclizumab; D005076:Exanthema / Q000139:chemically induced; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000009:adverse effects* / Q000627:therapeutic use*; D007166:Immunosuppressive Agents / Q000009:adverse effects* / Q000627:therapeutic use*; D053645:Interleukin-2 Receptor alpha Subunit; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D015375:Receptors, Interleukin-2 / Q000037:antagonists & inhibitors*; D012010:Red-Cell Aplasia, Pure / Q000188:drug therapy*
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; C508017:IL2RA protein, human; D007074:Immunoglobulin G; D007166:Immunosuppressive Agents; D053645:Interleukin-2 Receptor alpha Subunit; D015375:Receptors, Interleukin-2; D000077561:Daclizumab