Use of eltrombopag, a thrombopoietin receptor agonist, in post-transplantation thrombocytopenia.

Persistent thrombocytopenia after stem cell transplantation can lead to increased morbidity and mortality [1,2]. The underlying causes are often multifactorial in this patient population [3,4]. In autologous transplantation, thrombocytopenia is usually a result of poor engraftment or a sign of impending disease relapse. In allogeneic stem cell transplantation, the etiology is often more complex with engraftment deficits, medication effects, graft versus host disease (GVHD), and other immunologic processes potentially contributing. Eltrombopag is an orally available nonpeptide thrombopoietin (TPO) receptor agonist which interacts with the transmembrane domain of the receptor on bone marrow megakaryocytes and upstream progenitor/stem cells. It has been studied in patients with chronic idiopathic thrombocytopenic purpura [5] and in patients with thrombocytopenia secondary to hepatitis C infection [6]. Unlike the case with recombinant human TPO, its use has not been associated with anti-platelet antibody production [7]. We report two cases of post-transplantation thrombocytopenia, one allogeneic and one autologous, where eltrombopag was given to treat prolonged thrombocytopenia. The use of eltrombopag in these two cases was effective in elevating platelet counts to levels that eliminated the need for platelet transfusions.