Long-term safety and efficacy of romiplostim for treatment of immune thrombocytopenia

Inhibition of platelet production and mediated by antiplatelet antibodies is a well-known mechanism causing low platelet counts in immune thrombocytopenia (ITP). Use of thrombopoietin receptor agonists increases platelet counts and decreases the risk of bleeding in patients with ITP. Two such thrombopoietin receptor agonists, romiplostim and eltrombopag, are approved by the US Food and Drug Administration to treat thrombocytopenia in adults, and most recently, children with persistent or chronic ITP. This review focuses on the efficacy data and safety analysis of the pooled data from the clinical trials evaluating romiplostim for treatment of adults with ITP. The rates of hemorrhage, thrombosis, hematologic and nonhematologic cancers, and myelodysplastic syndrome were not overrepresented among the groups who received romiplostim versus placebo or other standard-of-care treatments. Yet, as after-market experience with thrombopoietin receptor agonists increases, there are emerging reports of increased incidence of thrombosis and bone marrow reticulin among patients who are treated with long-term use of these agents. Ongoing clinical research will continue to evaluate romiplostim's efficacy and safety in other primary and secondary thrombocytopenic states.