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Long‐term use of the thrombopoietin‐mimetic romiplostim in children with severe chronic immune thrombocytopenia (ITP)
Author(s) -
Bussel James B.,
Hsieh Loan,
Buchanan George R.,
Stine Kimo,
Kalpatthi Ram,
Gnarra David J.,
Ho Richard H.,
Nie Kun,
Eisen Melissa
Publication year - 2015
Publication title -
pediatric blood and cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.116
H-Index - 105
eISSN - 1545-5017
pISSN - 1545-5009
DOI - 10.1002/pbc.25136
Subject(s) - romiplostim , medicine , thrombopoietin , adverse effect , splenectomy , platelet , surgery , pediatrics , genetics , spleen , stem cell , haematopoiesis , biology
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 × 10 9 /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 × 10 9 /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 1 µg/kg/week to maintain platelet counts (50–200 × 10 9 /L, maximum dose 10 µg/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 × 10 9 /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 × 10 9 /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. Pediatr Blood Cancer 2015;62:208–213. © 2014. The Authors. Pediatr Blood & Cancer published by Wiley Periodicals, Inc.