Eltrombopag: a review of its use in patients with severe aplastic anaemia.

Eltrombopag (Promacta®) is an orally active thrombopoietin receptor agonist recently approved in the US for the treatment of patients with severe aplastic anaemia who have had an insufficient response to immunosuppressive therapy. This article reviews the efficacy and tolerability of eltrombopag in this indication and overviews its pharmacological properties. Eltrombopag does not compete with thrombopoietin and binds to a different site on the receptor, producing additive effects. It stimulates haematopoietic stem cells and promotes haematopoietic recovery in patients with aplastic bone marrow. Eltrombopag increased platelet counts and can also increase red blood cell and neutrophil counts. In patients with severe aplastic anaemia refractory to prior immunosuppressive therapy, oral eltrombopag at dosages ≤150 mg once daily for 12-16 weeks produced a haematological response in at least one cell lineage in 40 % of patients. Trilineage responses were achieved in nearly one-half of the responders during extended treatment. In robust responders, stable haematological counts were maintained after eltrombopag discontinuation. Eltrombopag was generally well tolerated, with increased liver transaminases as the only dose-limiting toxicity. Clonal cytogenetic abnormalities were observed in 19 % of patients and dysplasia in 5 % of patients.