Current and Future Possibilities for Influencing Immune Thrombocytopenia
The possibilities for treating immune thrombocytopenia (ITP) are quite broad today, with a major advancement for many patients being the advent of thrombopoietin receptor agonists. However, for some patients, optimal treatment is still not available, and their hope lies in further research.
Current Treatment Options for ITP
Immune thrombocytopenia is an autoimmune disease characterized by the destruction of platelets and decreased platelet production. The result is a reduced platelet count and an increased risk of bleeding. Given the immunological mechanisms of ITP etiopathogenesis, the first line of treatment usually involves corticosteroids or intravenous immunoglobulins (IVIG). If there is an insufficient response to first-line therapy, other options include the administration of anti-CD20 antibody (rituximab), thrombopoietin receptor agonists (TPO-RA), or immunosuppressants, or performing a splenectomy.
Mechanisms and Benefits of TPO-RA
TPO-RAs not only increase platelet production from megakaryocytes but also improve megakaryocyte proliferation in the bone marrow. Some research even suggests that TPO-RAs may positively influence anti-platelet immunity as well. Data from studies show that TPO-RAs are well-tolerated and very effective for many patients with ITP. They increase and maintain platelet counts even in refractory and pre-treated patients. Furthermore, it has been shown in numerous cases that it is possible to gradually reduce or discontinue other treatments, or even the TPO-RAs themselves.
Outlook for the Near Future
Despite the significant change brought about by the advent of TPO-RAs in the therapy of ITP, there are still numerous patients for whom currently available treatments do not work. Therefore, new substances are being developed that could be used either alone or in combination with established treatments. The most recent addition − in 2020 − is a tyrosine kinase inhibitor (TKI) fostamatinib, registered by the European Medicines Agency (EMA), which has proven efficacy against spleen tyrosine kinase (SYK). Its active metabolite inhibits the signaling of Fc-activating and B-cell receptors, thereby reducing antibody-mediated platelet destruction. It is indicated for patients refractory to other types of chronic ITP treatments. The State Institute for Drug Control (SÚKL) is currently gathering data to determine the reimbursement of this new drug from health insurance. The expert assessment, along with the issuance of an opinion, is also being contributed to by the Czech Hematology Society ČLS JEP.
Further research is focused on influencing mechanisms responsible for platelet destruction and possibly understanding and influencing other mechanisms involved in the manifestation of ITP.
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Sources:
1. Witkowski M., Witkowska M., Robak T. Autoimmune thrombocytopenia: current treatment options in adults with a focus on novel drugs. Eur J Haematol 2019; 103 (6): 531−541, doi: 10.1111/ejh.13319.
2. Meeting Note No. 16 from the Committee of the Czech Hematology Society ČLS JEP, April 25, 2022. Available at: www.hematology.cz/wp-content/uploads/2022/04/220425-Schuze-Zapis.pdf
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