A Randomized, Double-Blind, Placebo-Controlled Phase 1/2 Study to Determine the Safety and Efficacy of Romiplostim in Children with Chronic Immune (Idiopathic) Thrombocytopenic Purpura (ITP).

Abstract

Abstract 680 Introduction: ITP is an autoimmune disorder characterized by thrombocytopenia due to accelerated destruction as well as suboptimal platelet production. Childhood ITP is most commonly an acute illness; however, chronic ITP (duration > 6 months) develops in 20%–30% of ITP cases. Romiplostim, a peptibody protein designed to increase platelet production, is approved for treating chronic ITP in adults. The objective of this study was to evaluate the safety and efficacy of romiplostim in the treatment of thrombocytopenia in children with chronic ITP. Patients and Methods: ITP patients aged 12 months to 20 × 109/L above baseline for 2 consecutive weeks without rescue therapy at any point during the treatment period). Treatment was initiated at 1 μg/kg once weekly by subcutaneous injection. The dose was adjusted in 2 μg/kg increments every two weeks, to a maximum dose of 10 μg/kg/week based on weekly platelet counts. The incidence of adverse events (AEs) during the 12-week treatment period and the number of patients achieving platelet counts >50 × 109/L for 2 consecutive weeks during the treatment period, or achieving an increase in platelet count >20 × 109/L above baseline for 2 consecutive weeks during the treatment period was recorded. Results: A total of 22 (romiplostim, 17; placebo, 5) patients were randomized; 16 (73%) were boys and 6 (27%) were girls. Eight patients had undergone splenectomy. The mean age was 9.5 (SD: 5.1) years, with 4 subjects aged 12 months - Conclusion: Treatment with romiplostim appeared to be well tolerated in pediatric ITP patients, with no new safety concerns observed in this study as compared to adults with chronic ITP. Romiplostim was effective in treating thrombocytopenia in children with chronic ITP. Disclosures: Buchanan:Amgen Inc.: Research Funding. Off Label Use: Use of romiplostim, a thrombopoietin mimetic, in treatment of thrombocytopenia in pediatric ITP patients. . Bomgaars:Novartis: Research Funding. Bussel:Eisai, Inc: Research Funding; Sysmex: Research Funding; Shionogi: Membership on an entity9s Board of Directors or advisory committees; Ligand: Membership on an entity9s Board of Directors or advisory committees, Research Funding; Immunomedics: Research Funding; Amgen: Equity Ownership, Membership on an entity9s Board of Directors or advisory committees, Research Funding; GlaxoSmithKline: Equity Ownership, Membership on an entity9s Board of Directors or advisory committees, Research Funding; Cangene: Research Funding; Genzyme: Research Funding; Scienta: Speakers Bureau. Nie:Amgen Inc.: Employment, Equity Ownership. Eisen:Amgen Inc.: Employment, Equity Ownership. Berger:Amgen Inc.: Employment, Equity Ownership.