Researchers affiliated with an international study have reported that long-term use of eltrombopag is safe and effective for the treatment of chronic idiopathic thrombocytopenic purpura (ITP). This study was presented at the 2007 meeting of the American Society of Hematology (ASH) in Atlanta, Georgia, December 10-11, 2007.[1]

Eltrombopag is an oral non-peptide thrombopoietin receptor agonist with a low immunogenic potential.  A Phase I trial of 73 subjects was previously presented demonstrating that this drug increases the platelet counts in healthy volunteers in a dose-dependent fashion.  The results of a Phase II placebo-controlled double-blind trial were presented at ASH 2006.  In this study, the platelet counts of 117 patients with chronic ITP were analyzed after six weeks of therapy with 30, 50, or 75 mg of daily eltrombopag. Notably, all patients in this trial had at least one prior form of therapy, and the patients were allowed to continue prednisone therapy while they received the test drug. Approximately 75% of the ITP patients exposed to the two higher daily doses of eltrombopag for six weeks had a median platelet count greater than 50,000/µl, and 40% of the patients had a platelet count greater than 200,000/µl. In contrast, patients receiving placebo had a mean platelet count of 16,000/µl.  Headache was the most common adverse event, and the remaining adverse events were mild.  These data have subsequently been published in the New England Journal of Medicine.[2] The data presented thus far, suggests that eltrombopag is a well-tolerated oral TPO-mimetic with excellent response rates in the treatment of chronic ITP. Other similar new agents for treatment of chronic ITP include romiplostim (AMG531) and AKR-501.

The EXTEND study involved 94 patients who had been previously enrolled on clinical trials of eltrombopag. The goal was to evaluate the long-term effects of eltrombopag of chronic administration of a titrated dose of eltrombopag. The starting dose of eltrombopag was 50/mg/day with the goal of maintaining platelet levels at 50,000. Ninety patients were evaluable for initial treatment, 17 were tapering other therapies for ITP, 46 were in the process of titrating eltrombopag to maintain platelet levels and 27 were in the long-term maintenance phase of treatment. Treatment duration averaged 151 days (2-333 days). Forty-three percent of patients in this trial had platelet levels <15,000 and 63% had evidence of bleeding. Seventy-three percent achieved a platelet count of 50,000 or greater. Most adverse events were described as mild. A separate presentation was made summarizing the safety of eltrombopag in ITP patients participating in four randomized trials.[3]

Comments: These data suggest that eltrombopag is effective for the long-term treatment of patients with chronic ITP.

Related News:

AMG 531 Maybe Effective in Treating Thrombocytopenia in Patients with MDS (06/11/2007)

Romiplostim (AMG531) Effective in Chronic Immune Thrombocytopenic Purpura (12/12/2007)

References: