Function of eltrombopag-induced platelets compared to platelets from control patients with immune thrombocytopenia

Johanna Haselboeck; Alexandra Kaider; Ingrid Pabinger; Simon Panzer

doi:10.1160/TH12-07-0522

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 2013; 109(04): 676-683
DOI: 10.1160/TH12-07-0522

Platelets and Blood Cells

Schattauer GmbH

Function of eltrombopag-induced platelets compared to platelets from control patients with immune thrombocytopenia

Johanna Haselboeck

¹Department of Medicine I, Division of Haematology and Haemostaseology, Medical University of Vienna, Vienna, Austria

,

Alexandra Kaider

²Center for Medical Statistics, Informatics and Intelligent Systems, Section for Clinical Biometrics, Medical University of Vienna, Vienna, Austria

,

Ingrid Pabinger^*

¹Department of Medicine I, Division of Haematology and Haemostaseology, Medical University of Vienna, Vienna, Austria

,

Simon Panzer^*

³Department of Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Vienna, Austria

› Author Affiliations

Abstract

Summary

Data on the in vivo function of platelets induced by the thrombopoietin receptor agonist eltrombopag are scarce. To assess a possible influence of eltrombopag we compared platelet function of eltrombopag-treated immune thrombocytopenia (ITP) patients (group 1; n=10) after treatment response to that from control ITP patients (group 2; n=12). We further analysed platelet function at baseline and after one, three, and four weeks of eltrombopag treatment and estimated daily changes of platelet function during the eltrombopag-induced platelet rise. The formation of platelet-monocyte aggregates (PMA), P-selectin expression [MFI], and platelet adhesion under high shear conditions (surface coverage, SC) in vivo and after in vitro addition of agonists (ADP, TRAP-6, Collagen) were similar between both groups after response to eltrombopag treatment. Only TRAP-6 induced a lower SC in the eltrombopag group (p=0.03). All platelet function parameters except for Collagen-induced P-selectin expression changed significantly during treatment with eltrombopag. PMA, naïve and after addition of ADP or TRAP-6 increased with increasing platelet counts. P-selectin expression decreased, when measured without and upon addition of ADP, increased in the presence of TRAP-6, and remained unchanged after addition of Collagen. SC increased during the eltrombopag-induced platelet rise. All significant changes of platelet function correlated to changes in platelet counts. Two patients developed venous thromboses during eltrombopag treatment, but no association with any distinct single platelet function parameter or combinations thereof was identifiable. Thus, eltrombopag-induced platelets function similar to those from control ITP patients without discernible increased hyper-reactivity.

Keywords

Eltrombopag - immune thrombocytopenia - ITP - platelet function - thrombopoietin agonist

Full Text

References

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