New treatments for idiopathic thrombocytopenic purpura: rethinking old hypotheses

BACKGROUND: The efficacy of thrombopoietin (TPO) mimetics in patients with idiopathic thrombocytopenic purpura (ITP) reaffirms that impaired platelet production is an important mechanism. New strategies to reduce platelet destruction, like rituximab, are also effective. OBJECTIVES: To describe the efficacy and safety of rituximab and the TPO mimetics, romiplostim and eltrombopag, and how they relate to ITP pathogenesis. METHODS: Narrative review summarizing full publications and meeting abstracts. RESULTS/CONCLUSIONS: A 4-week course of rituximab is associated with a platelet count response in 60% of patients with ITP, and durable responses have been observed. Subtle increases in infection have been reported. Romiplostim and eltrombopag are each associated with a 60 - 85% response while on treatment. Transient bone marrow reticulin with romiplostim and elevated liver enzymes with eltrombopag are rare side effects. The application of these agents in non-splenectomized patients requires further study.