New options after first-line therapy for chronic immune thrombocytopenic purpura.

PURPOSE

The pharmacology of immunomodulatory agents and thrombopoietic agonists with novel mechanisms of action, the role of these agents in the management of chronic immune thrombocytopenic purpura (ITP), and potential adverse effects that may complicate use of these agents are reviewed.

SUMMARY

Long mired by the toxicity of available treatments and a paucity of randomized, controlled trials evaluating therapeutic options, the treatment of chronic ITP has advanced in recent years. Based on an improved understanding of the pathophysiology of chronic ITP, these advances include the incorporation of immunomodulatory therapy and the development of thrombopoietic stimulating agents. Rituximab, romiplostim, and eltrombopag are promising agents that have recently demonstrated the ability to increase platelet counts in patients with chronic ITP. They have shown benefit in splenectomized and nonsplenectomized patients, including those who have not sustained benefit from multiple other agents. At this time there are insufficient data on the long-term risk associated with continued use of thrombopoietic agents beyond six months. The risk of thrombosis, myelofibrosis, and development of hematologic malignancies with continued use of thrombopoietic stimulating agents is unknown.

CONCLUSION

Rituximab, romiplostim, and eltrombopag are effective in some patients that are unresponsive to other therapies and warrant consideration in patients with relapsed or refractory ITP. Further studies need to be done to define the risks of long-term use of thrombopoietic stimulating agents and the benefit of these novel agents in comparison to other therapies that provide a durable response off therapy.