Quantifying the reduction in immunoglobulin use over time in patients with chronic immune thrombocytopenic purpura receiving romiplostim (AMG 531)

Patients with Immune thrombocytopenic purpura (ITP) often require immunoglobulin (Ig) therapy with intravenous 19 (IVIG) or anti-D to prevent or treat the serious bleeding events. Because the thrombopoietin (TPO) mimetic romiplostim (AMG 531; Nplate) elevates platelet counts in patients with chronic ITP, we quantified to what extent it reduced the incidence of Ig rescue therapy in two randomized (vs. placebo) trials of romiplostim for chronic ITP. Our analysis shows that significantly fewer romiplostim patients than placebo patients required Ig therapy over the course of 24 weeks (1-6% vs. 19-37%, respectively; P <0.05 for each 4-week interval), and romiplostim-treated patients were 5.31-fold less likely to receive Ig therapy (P <0.001).