Systematic Review and Meta-Analysis Of Rituximab For The Treatment Of Immune Thrombocytopenia In Adults

Rituximab, a monoclonal anti-CD20 antibody is commonly used to treat immune thrombocytopenia (ITP). Results of randomized controlled trials (RCTs) evaluating the efficacy of rituximab are conflicting. We conducted a systematic review and meta-analysis of RCTs to determine a more precise estimate of the effect of rituximab on platelet count response in adults with ITP.

We searched MEDLINE (from 1946), EMBASE (from 1980), and the Cochrane database using the MeSH terms antibodies, monoclonal, and purpura thrombocytopenia idiopathic and the textwords rituximab, rituxan, mabthera, and immune thrombocytopenic purpura. In duplicate, two reviewers independently assessed study eligibility, abstracted data and assessed each study for methodological quality.

We identified 4 RCTs (n=360) that met our eligibility criteria. Each trial compared rituximab to placebo combined with other ITP treatments, including dexamethasone, or standard of care. Each trial enrolled non-splenectomized patients only. The likelihood of achieving a platelet count >100 x10⁹/L at 6 months was greater with rituximab than placebo (relative risk [RR] 1.38, 95% CI 1.08-1.76). More patients receiving rituximab achieved a platelet count greater than 50 x10⁹/L at 6 months (RR 1.46, 95% CI 1.18-1.80) compared to placebo. Rituximab was not associated with a reduction in the risk of any bleeding (RR 1.49, 95% CI 0.55-4.04) or an increase in the risk of infection (RR 1.33, 95% CI 0.74-2.38).

Rituximab is associated with a modest increase in the likelihood of achieving a platelet count greater than >100 x10⁹/L at 6 months compared to placebo. No significant reduction in bleeding or increased risk of infection was observed at 6 months. Randomized trials were generally small, with relatively short follow-up. Large pragmatic multicenter comparative trials are needed to examine durability of response over a longer period of follow-up.

Arnold:Amgen: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; GlaxoSmithKline: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Hoffman-LaRoche: Research Funding. Lim:Leo Pharma: Honoraria, Research Funding; Pfizer: Consultancy, Honoraria. Crowther:Asahi Kasai: Membership on an entity’s Board of Directors or advisory committees; Baxter: Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Boehringer Ingelheim: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees; CSL Behring: Speakers Bureau; Leo Pharma: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Merck: Consultancy; Octapharma: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Research Funding; Sanofi-Aventis: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Viropharma: Membership on an entity’s Board of Directors or advisory committees.