Long-term use of the thrombopoietin-mimetic romiplostim in children with severe chronic immune thrombocytopenia (ITP)

James B. Bussel, Loan Hsieh, George R. Buchanan, Kimo Stine, Ram Kalpatthi, David J. Gnarra, Richard H. Ho, Kun Nie, Melissa Eisen

Research output: Contribution to journalArticle

37 Scopus citations

Abstract

Background: Treatment of chronic severe pediatric ITP is not well studied. In a phase 1/2 12-16-week study, 15/17 romiplostim-treated patients achieved platelet counts ≥50×109/L, and romiplostim treatment was well tolerated. In a subsequent open-label extension (≤109 weeks), 20/22 patients received romiplostim; all achieved platelet counts >50×109/L. Twelve patients continued in a second extension (≤127 weeks). Longitudinal data from start of romiplostim treatment through the two extensions were evaluated to investigate the safety and efficacy of long-term romiplostim treatment in chronic severe pediatric ITP. Procedure: Patients received weekly subcutaneous romiplostim, adjusted by 1μg/kg/week to maintain platelet counts (50-200×109/L, maximum dose 10μg/kg). Bone marrow examinations were not required. Results: At baseline, patients were median age 10.0 years; median ITP duration 2.4 years; median platelet count 13×109/L; 73% were male; and 36% had prior splenectomy. Median romiplostim treatment duration was 167 weeks (Q1, Q3: 78,227 weeks), and median average weekly dose was 5.4μg/kg (Q1, Q3: 4.3, 8.0μg/kg). Seven patients discontinued treatment: four withdrew consent, two were noncompliant, and one received alternative therapy. None withdrew because of adverse events (AEs). After the first 12 weeks, median platelet counts remained >50×109/L. Eight (36.4%) patients received rescue medication, and 14 (63.6%) used concurrent ITP therapy. Seven patients (31.8%) reported serious AEs, and two (9.1%) reported life-threatening AEs (both thrombocytopenia); there were no serious AEs attributed to treatment and no fatalities. Conclusions: Long-term romiplostim treatment in this small cohort increased and maintained platelet counts for over 4 years in children with ITP with good tolerability and without significant toxicity.

Original languageEnglish (US)
Pages (from-to)208-213
Number of pages6
JournalPediatric Blood and Cancer
Volume62
Issue number2
DOIs
StatePublished - Feb 1 2015

Keywords

  • Autoimmunity
  • Bleeding
  • Platelets
  • Thrombopoietin

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Hematology
  • Oncology

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