Background Patients with chronic immune thrombocytopenic purpura (ITP) only require treatment if they are bleeding, or prior to scheduled operations. Patients are also treated if platelet counts are very low. Some patients become refractory, relapse or do not respond to treatment with steroids. Splenectomy is effective in raising the platelet count in most patients, but as spontaneous remission may occur even after 1 year or more, it is justified to defer splenectomy. Furthermore, splenectomy and/or first-line treatment modalities may not suit all patients. Therefore, alternatives are desirable.
Materials This review will focus on anti-B cell therapy with rituximab, and two thrombopoietin mimetic agents that have entered clinical trials, AMG 531 and eltrombopag. These therapeutics have been studied in patients who were refractory to first-line treatment and/or splenectomy, and to defer splenectomy.
Results There are no controlled trials with rituximab, but clinical experience has shown a success rate of 40% to 60%. Encouraging phase 1 and 2 data have been published for both thrombopoietin mimetics; preliminary data from an open-label extension trial with AMG 531 and from phase 3 studies with eltrombopag further confirm their efficacy.
Conclusion Clinical experience will ultimately determine the appropriate indications of these new treatments for ITP.