title: Long-term use of the thrombopoietin-mimetic romiplostim in children with severe chronic immune thrombocytopenia (ITP).
abstract: 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.
  
  
  
  Patients received weekly subcutaneous romiplostim, adjusted by 1 µg/kg/week to maintain platelet counts (50-200 × 109/L, maximum dose 10 µg/kg). Bone marrow examinations were not required.
  
  
  
  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 5.4 µg/kg (Q1, Q3: 4.3, 8.0 µg/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.
  
  
  
  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. Pediatr Blood Cancer 2015;62:208-213. © 2014. The Authors. Pediatr Blood & Cancer published by Wiley Periodicals, Inc.
authors.affiliation: Department of Pediatrics, Division of Hematology, Weill Medical College of Cornell University, New York, New York.
authors.forename: James B
authors.initials: JB
authors.lastname: Bussel
authors.affiliation: Children's Hospital of Orange County/University of California, Irvine, California.
authors.forename: Loan
authors.initials: L
authors.lastname: Hsieh
authors.affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas.
authors.forename: George R
authors.initials: GR
authors.lastname: Buchanan
authors.affiliation: Arkansas Children's Hospital, Little Rock, Arkansas.
authors.forename: Kimo
authors.initials: K
authors.lastname: Stine
authors.affiliation: Children's Mercy Hospital, Kansas City, Missouri.
authors.forename: Ram
authors.initials: R
authors.lastname: Kalpatthi
authors.affiliation: Children's Hospital and Medical Center, University of Nebraska Medical Center, Omaha, Nebraska.
authors.forename: David J
authors.initials: DJ
authors.lastname: Gnarra
authors.affiliation: Department of Pediatrics, Monroe Carell Jr. Children's Hospital at Vanderbilt, Nashville, Tennessee.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Ho
authors.affiliation: Amgen Inc., Thousand Oaks, California.
authors.forename: Kun
authors.initials: K
authors.lastname: Nie
authors.affiliation: Amgen Inc., Thousand Oaks, California.
authors.forename: Melissa
authors.initials: M
authors.lastname: Eisen
mesh_terms: D000293:Adolescent; D001792:Blood Platelets / Q000187:drug effects*; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D010976:Platelet Count; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000188:drug therapy*; D011961:Receptors, Fc / Q000627:therapeutic use*; D053628:Receptors, Thrombopoietin / Q000819:agonists*; D011993:Recombinant Fusion Proteins / Q000009:adverse effects / Q000627:therapeutic use*; D013926:Thrombopoietin / Q000009:adverse effects / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D011961:Receptors, Fc; D053628:Receptors, Thrombopoietin; D011993:Recombinant Fusion Proteins; D013926:Thrombopoietin; C488777:romiplostim
keywords: autoimmunity; bleeding; platelets; thrombopoietin