Study further supports eltrombopag’s efficacy in adult chronic ITP

More than half of patients with chronic idiopathic thrombocytopenic purpura assigned to the 50-mg dose of eltrombopag, an oral thrombopoietin-receptor agonist, responded to the treatment by achieving platelet counts ≥50,000 per mcL.

“[This] report clearly shows that eltrombopag can further enhance platelet production, which supports the idea of impaired thrombopoiesis in adults with ITP,” Simon Panzer, MD, of the clinical division of hematology and hemostaseology at the Medical University Vienna, wrote in an accompanying editorial.

Researchers enrolled 110 patients from 63 sites in 23 countries into the phase-3, double blind, placebo-controlled study. All patients had chronic ITP, platelet counts <30,000 per mcL and had tried at least one prior treatment for their disease.

Patients were randomly assigned in a 2:1 ratio to 50 mg eltrombopag (Promacta, GlaxoSmithKline; n=73) or placebo (n=37). Patients who did not achieve target platelet counts by week three could increase their eltrombopag dose to 75 mg.

Fifty-nine percent of patients assigned eltrombopag responded compared with 16% of those assigned placebo (OR=9.61; 95% CI, 3.31-27.86). This response was not affected by predefined study stratification criteria such as baseline platelet counts, concomitant ITP medications or splenectomy status.

Twenty-nine percent of patients who increased their dose to 75 mg eltrombopag also responded. Those patients assigned eltrombopag had less bleeding at any time than those assigned placebo. Patients in both groups had a similar frequency of grade-3 and grade-4 adverse events.

Lancet. 2009;373:641-648.