Systematic Review: Efficacy and Safety of Rituximab for Adults with Idiopathic Thrombocytopenic Purpura

2 January 2007 | Volume 146 Issue 1 | Pages 25-33

Background: Rituximab, a monoclonal anti-CD20 antibody, is increasingly used to treat idiopathic thrombocytopenic purpura (ITP).

Purpose: To systematically review the literature on the efficacy and safety of rituximab for the treatment of adults with ITP.

Data Sources: MEDLINE, EMBASE, the Cochrane Library, abstracts from the American Societies of Hematology and Clinical Oncology annual meetings, and bibliographies of relevant articles and reviews were searched in duplicate until April 2006.

Study Selection: Descriptive and comparative studies in any language that met predefined inclusion criteria were eligible. Efficacy analysis was restricted to studies enrolling 5 or more patients.

Data Extraction: Platelet count response, toxicities, dose, previous treatments, baseline platelet count, duration of ITP, study design, and sources of funding were extracted in duplicate.

Data Synthesis: We identified 19 eligible reports on efficacy (313 patients) and 29 on safety (306 patients). Weighted means for complete response (platelet count > 150 x 10⁹ cells/L) and overall response (platelet count > 50 x 10⁹ cells/L) with rituximab were 43.6% (95% CI, 29.5% to 57.7%) and 62.5% (CI, 52.6% to 72.5%), respectively. Responses lasted from 2 to 48 months. Nearly all patients had received corticosteroids, and 53.8% had undergone splenectomy. Nine patients (2.9%) died.

Limitations: There were no controlled studies, and no studies met all criteria for study quality. Reported deaths could not necessarily be attributed to rituximab. Overall, the number of rituximab-treated patients with ITP reported in the literature is small.

Conclusions: Rituximab resulted in an overall platelet count response in 62.5% of adults with ITP. However, this finding derives from uncontrolled studies that also reported significant toxicities, including death in 2.9% of cases. These data suggest that providers should avoid indiscriminate use of rituximab and that randomized, controlled trials of rituximab for ITP are urgently needed.

Author and Article Information

From McMaster University and Juravinski Cancer Centre, Hamilton, Ontario, Canada; Insubria University, Varese, Italy; National Cancer Institute of Canada Clinical Trials Group, Kingston, Ontario, Canada; Queen’s University, Kingston, Ontario, Canada; University of Waterloo, Waterloo, Ontario, Canada.

Acknowledgments: The authors thank the staff of the McMaster Transfusion Research Program for their administrative assistance with this research.

Grant Support: Dr. Arnold is a research fellow of the Canadian Institutes for Health Research and Canadian Blood Services; Dr. Crowther is a Career Investigator of the Heart and Stroke Foundation of Ontario; Dr. Cook is a Canada Research Chair; Dr. Fraser is a research fellow of The Terry Fox Foundation through an award from the National Cancer Institute of Canada; Dr. Lim is the recipient of the ISTH Clinical Research Fellowship.

Potential Financial Conflicts of Interest: Consultancies: R.M. Meyer (Hoffmann-LaRoche, Canada); Honoraria: R.M. Meyer (Hoffmann-LaRoche, Canada); Grants received: D.M. Arnold (Hoffmann-LaRoche, Canada); Grants pending: D.M. Arnold (Roche Canada).

Corresponding Author: Donald M. Arnold, MD, McMaster University Health Sciences Center, Room 3N-43, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada; e-mail, arnold{at}mcmaster.ca.

Current Author Addresses: Dr. Arnold and Mr. Sigouin: McMaster University Health Sciences Center, Room 3N-43, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada.

Dr. Dentali: Department of Clinical Medicine, Insubria University, Viale Borri 57, Varese, Italy 21100.

Dr. Crowther and Dr. Lim: St. Joseph’s Hospital, 50 Charlton Avenue East, Room L-208, Hamilton, Ontario L8N 4A6, Canada.

Dr. Meyer: Clinical Trials Division, Cancer Research Institute, Queen’s University, 10 Stuart Street, Kingston, Ontario K7L 3N6, Canada.

Dr. Cook: University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.

Dr. Fraser: Juravinski Cancer Centre, 699 Concession Street, Hamilton, Ontario L8V 5C2, Canada.

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