Brief Communication: Successful Treatment of Pure Red-Cell Aplasia with an Anti–Interleukin-2 Receptor Antibody (Daclizumab)

Brief Communication: Successful Treatment of Pure Red-Cell Aplasia with an Anti–Interleukin-2 Receptor Antibody (Daclizumab)

From National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland.

Abstract

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.

Design: Pilot study.

Setting: Federal government research hospital.

Patients: 15 patients with idiopathic PRCA.

Intervention: 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 × 10⁹ cells/L or less and bone marrow showing absent or diminished erythroid precursors.

Measurements: 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.

Limitations: 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.

Article and Author Information

Acknowledgments: The authors thank Colin Wu, who provided statistical expertise and helped develop stopping rules for the study, and Barbara Weinstein, who screened and recruited patients and managed the data for the study.
Grant Support: No outside funding was received for this study.
Potential Financial Conflicts of Interest: None disclosed.
Requests for Single Reprints: Elaine M. Sloand, MD, Hematology Branch, National Heart, Lung, and Blood Institute, 9000 Rockville Pike, Building 10 CRC 4E5230, Bethesda, MD 20892; e-mail, sloande{at}nih.gov.
Current Author Addresses: Dr. Sloand: Hematology Branch, National Heart, Lung, and Blood Institute, 9000 Rockville Pike, Building 10 CRC 4E5230, Bethesda, MD 20892.
Drs. Scheinberg and Young: Hematology Branch, National Heart, Lung, and Blood Institute, 9000 Rockville Pike, Building 10 CRC 3E, 3-5142, Bethesda, MD 20892.
Dr. Maciejewski: Cleveland Clinic Foundation, Taussig Cancer Center, 9500 Euclid Avenue, Cleveland, OH 22195.
Author Contributions: Conception and design: E.M. Sloand, J. Maciejewski, N.S. Young.
Analysis and interpretation of the data: E.M. Sloand, J. Maciejewski, N.S. Young.
Drafting of the article: E.M. Sloand, J. Maciejewski, N.S. Young.
Critical revision of the article for important intellectual content: E.M. Sloand, N.S. Young.
Final approval of the article: E.M. Sloand, J. Maciejewski, N.S. Young.
Provision of study materials or patients: E.M. Sloand, P. Scheinberg, J. Maciejewski, N.S. Young.
Obtaining of funding: N.S. Young.
Administrative, technical, or logistic support: E.M. Sloand, N.S. Young.
Collection and assembly of data: E.M. Sloand.