Blood Cells

A double-blind, multicenter, phase III study of Oral Eltrombopag for the treatment of chronic Idiopathic Thrombocytopenic Purpura (ITP), found that long-term therapy with eltrombopag, a thrombopoietin-receptor agonist, compared with placebo treatment significantly increased platelet counts, decreased bleeding symptoms, allowed for a reduction of baseline ITP therapy, and reduced the use of rescue medications in previously treated patients with chronic ITP. In chronic ITP, low blood platelet counts persist unless treated and can last for an indefinite amount of time.

In this study Gregory Cheng, MD and his team of researchers at the Chinese University of Hong Kong, Hong Kong, China, stratified 197 patients with platelet counts less than 30,000 microliters by splenectomy status, use of baseline ITP medication, and platelets of less than or equal to 15,000 microliters. Patients were randomized to receive either eltrombopag at a starting dose of 50 mg once daily (135 patients) or placebo once daily (62 patients).

Depending on individual platelet response, the dose of eltrombopag could be titrated within a range from 25 mg once daily to a maximum dose of 75 mg once daily. The primary endpoint of the study was the odds of achieving platelet counts between 50,000 and 400,000 microliters in patients receiving eltrombopag as compared with placebo. To measure the drug?s safety, bleeding symptoms were prospectively evaluated using the WHO Bleeding Scale.

Patients who received eltrombopag were eight times more likely to achieve platelet counts of 50,000 to 400,000 microliters during the six-month treatment period as compared with those in the placebo arm. While baseline median platelet counts were 16,000 microliters in both groups, platelet counts never exceeded 30,000 microliters in the placebo group. This is in contrast to median platelet counts rising to 36,000 microliters in the eltrombopag group after one week of treatment and ranging from 52,000 to 91,000 microliters for the remainder of the study. Median platelet counts returned to baseline levels two weeks after stopping eltrombopag.

Significantly fewer patients treated with eltrombopag experienced any bleeding or clinically significant bleeding throughout the study as compared with those in the placebo arm. Additionally, more patients in the eltrombopag arm were able to stop or reduce other ITP medication and required less rescue therapy compared with those in the placebo group. Overall incidence of adverse events was similar in both treatment groups and was mostly mild to moderate.

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Last editorial review: December 9, 2008.

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