The pathogenesis of chronic idiopathic thrombocytopenic purpura (ITP) involves
antibody-mediated platelet destruction and reduced platelet production. Stimulation
of platelet production may be an effective treatment for this disorder.
We conducted a trial in which 118 adults with chronic ITP and platelet counts of
less than 30,000 per cubic millimeter who had had relapses or whose platelet count
was refractory to at least one standard treatment for ITP were randomly assigned to
receive the oral thrombopoietin-receptor agonist eltrombopag (30, 50, or 75 mg daily)
or placebo. The primary end point was a platelet count of 50,000 or more per cubic
millimeter on day 43.
In the eltrombopag groups receiving 30, 50, and 75 mg per day, the primary end
point was achieved in 28%, 70%, and 81% of patients, respectively. In the placebo
group, the end point was achieved in 11% of patients. The median platelet counts
on day 43 for the groups receiving 30, 50, and 75 mg of eltrombopag were 26,000,
128,000, and 183,000 per cubic millimeter, respectively; for the placebo group the
count was 16,000 per cubic millimeter. By day 15, more than 80% of patients receiving
50 or 75 mg of eltrombopag daily had an increased platelet count. Bleeding also
decreased during treatment in these two groups. The incidence and severity of adverse
events were similar in the placebo and eltrombopag groups.
Eltrombopag increased platelet counts in a dose-dependent manner in patients with
relapsed or refractory ITP. (ClinicalTrials.gov number, NCT00102739.)
資料來源：n engl j med 357;22 www.nejm.org november 29, 2007