Hematology
Chronic Immune Thrombocytopenia
Achieving Safe Platelet Counts in Immune Thrombocytopenia With Thrombopoietin Receptor Agonists
Overview
The main goal of treatment in patients with chronic immune thrombocytopenia (ITP) is to minimize the bleeding risk, and this should be done by achieving safe platelet counts with minimal side effects. After initial treatment, commonly with corticosteroids or intravenous immunoglobulin (IVIg), many patients with chronic ITP will require treatment with a second-line therapy, which commonly includes a thrombopoietin receptor agonist (TPO-RA), rituximab, or splenectomy. The TPO-RAs and splenectomy have been associated with positive long-term effects on platelet counts, with similar rates of response of 85% to 95% observed. Rituximab is associated with a lower (approximately 62%) platelet count response rate in adult patients with ITP, and it is associated with treatment toxicity and morbidity in some individuals. In addition, rituximab has been found to have a 38% response rate at 1 year and only a 21% response rate at 5 years in adult patients. Although effective, a risk of thrombosis and severe sepsis have been reported with splenectomy, but the TPO-RAs have been reported to have good tolerability, low toxicity rates, and long-term efficacy.
Expert Commentary
Howard A. Liebman, MD
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“Due to treatment with the TPO-RAs, we rarely see true refractory ITP anymore. It is very rare nowadays because we can get safe platelet counts in patients for a long period of time with TPO-RA treatment.”
Patients will respond to a TPO-RA even if they do not have ITP. Therefore, I love to see an initial response to treatment with corticosteroids in patients with ITP. I know that I am not going to cure the patient or provide long-term platelet control with corticosteroids 90% of the time, but an initial treatment response to corticosteroids or IVIg tells me that this is an immune-mediated process. That is very important. You have to use some immune modulation agent to maintain the platelet count because you do not want to keep patients on IVIg or corticosteroids long-term. Although patients improve their platelet count on corticosteroids or IVIg, you cannot wean them off of them and have patients unmaintained. As second-line therapy, platelet response with rituximab is only maintained in 21% of adult patients at 5 years, and thus is simply not a cure for approximately 80% of individuals. Therefore, you can use a TPO-RA at this point as second-line therapy to achieve safe platelet counts long-term. Due to treatment with the TPO-RAs, we rarely see true refractory ITP anymore. It is very rare nowadays because we can get safe platelet counts in patients for a long period of time with TPO-RA treatment.
References
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Arnold DM, Dentali F, Crowther MA, et al. Systematic review: efficacy and safety of rituximab for adults with idiopathic thrombocytopenic purpura. Ann Intern Med. 2007;146(1):25-33.
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Kuter DJ, Bussel JB, Newland A, et al. Long-term treatment with romiplostim in patients with chronic immune thrombocytopenia: safety and efficacy. Br J Haematol. 2013;161(3):411-423.
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Provan D, Stasi R, Newland AC, et al. International consensus report on the investigation and management of primary immune thrombocytopenia. Blood. 2010;115(2):168-186.
Saleh MN, Bussel JB, Cheng G, et al; EXTEND Study Group. Safety and efficacy of eltrombopag for treatment of chronic immune thrombocytopenia: results of the long-term, open-label EXTEND study. Blood. 2013;121(3):537-545.
Thai LH, Mahévas M, Roudot-Thoraval F, et al. Long-term complications of splenectomy in adult immune thrombocytopenia. Medicine (Baltimore). 2016;95(48):e5098.
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