A Pilot Study of the Thrombopoietin-Receptor Agonist Eltrombopag in Refractory Aplastic Anemia Patients

Study Summary

Severe aplastic anemia (SAA) is a life-threatening blood disease which can be effectively treated with immunosuppressive drug regimens or allogeneic stem cell transplantation. However, 20-40% of patients without transplant options do not respond to immunosuppressive therapies, and have persistent severe cytopenias, requiring regular platelet transfusions, which are expensive and inconvenient, and are a risk for further serious bleeding complications. Thrombopoietin (TPO) is the principal endogenous regulator of platelet production and also stimulates hematopoietic stem and progenitor cells. A small molecule oral TPO-agonist, eltrombopag has been shown to increase platelets in healthy subjects and in patients with immune thrombocytopenic purpura (ITP), and received FDA approval in 2008 for the treatment of thrombocytopenia in ITP. This Phase 2, non-randomized pilot study of eltrombopag in aplastic anemia patients with immunosuppressive therapy refractory thrombocytopenia will test the safety and potential efficacy of eltrombopag treatment patients with refractory thrombocytopenia following immunosuppression for aplastic anemia. Subjects will initiate study medication at an oral dose of 50 mg/day, which will be increased up to 150 mg/day as clinically indicated to the lowest dose that maintains a stable platelet count 20,000/(micro)L above baseline while maximizing tolerability. Response will be assessed at 3-4 months. Platelet response is defined as platelet count increases to 20,000/L above baseline at three months. or stable platelet counts with transfusion independence for a minimum of 8 weeks. Erythroid response for subjects with a pretreatment hemoglobin of less than 9 g/dL will be defined as an increase in hemoglobin by greater than or equal to 1.5g/dL without packed red blood cell (PRBC) transfusion support, or a reduction in the units of transfusions by an absolute number of at least 4 PRBC transfusions for eight consecutive weeks compared with the pretreat

Primary Outcome

Defined as unilineage or multilineage recovery by 1 or more of the following: 1) platelet response (increase to 20 × 103/μL above baseline or stable platelet counts with transfusion independence for a minimum of 8 weeks in those who were transfusion dependent on entry into the protocol); (2) erythroid response (when pretreatment hemoglobin was \<9 g/dL, defined as an increase in hemoglobin by 1.5 g/dL or, in transfused patients, a reduction in the units of packed red blood cell transfusions by a

Interventions

• DRUG Eltrombopag