Romiplostim treatment for children with immune thrombocytopenia: Results of an integrated database of five clinical trials

Background: Treatment for chronic immune thrombocytopenia (cITP) in children is largely limited to immunosuppressive agents. Thrombopoietin receptor agonists (TRAs) have been used to treat cITP in adults for over a decade. The objective of this integrated analysis was to examine the safety and efficacy of the TRA romiplostim in children with ITP. Methods: We examined efficacy and safety in children with ITP across five romiplostim trials: final data from two double-blind placebo-controlled trials and two open-label extensions, and interim data from an ongoing single-arm trial. Results: Patients (n\ua0=\ua024 initially placebo; n\ua0=\ua0262 initially romiplostim) had a median age of 10.0\ua0years (Q1: 6.0, Q3: 13.0), ITP duration of 1.9\ua0years (Q1: 1.0, Q3: 4.0), and baseline platelet count of 14.3\ua0×\ua010/L (Q1: 7.5, Q3: 23.0). Among 282 patients receiving romiplostim, median treatment duration was 65\ua0weeks (range 8-471\ua0weeks) and median weekly dose was 6.6\ua0μg/kg (range 0.1-9.7\ua0μg/kg). Overall, 89% of romiplostim-treated patients had platelet responses. Nineteen patients (7%) maintained treatment-free responses for ≥6\ua0months while withholding all ITP therapy. Grade 3 and 4 adverse events of bleeding occurred in 10% and 12\ua0months at baseline. Conclusions: Across five pediatric clinical trials, romiplostim was well tolerated. Most patients had a platelet response; some maintained responses for at least 6\ua0months while withholding all ITP therapy