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Platelet Biology & its Disorders
Long-term treatment with romiplostim and treatment-free platelet responses in children with chronic immune thrombocytopenia
Ferrata Storti Foundation
Haematologica 2019 Volume 104(11):2283-2291
Michael D. Tarantino,1 James B. Bussel,2 Victor S. Blanchette,3 Donald Beam,4 John Roy,5 Jenny Despotovic,6 Ashok Raj,7 Nancy Carpenter,8 Bhakti Mehta,9 and Melissa Eisen9
1The Bleeding and Clotting Disorders Institute, University of Illinois College of Medicine- Peoria, Peoria, IL, USA; 2Department of Pediatrics, Division of Hematology, Weill Cornell Medicine, New York, NY, USA; 3Department of Pediatrics, University of Toronto, Division of Hematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada; 4Cook Children’s Medical Center, Fort Worth, TX, USA; 5Children’s Health Queensland and Pathology Queensland, South Brisbane, Queensland, Australia and The University of Queensland, Saint Lucia, Queensland, Australia; 6Texas Children’s Hematology Center, Houston, TX, USA; 7Pediatric Cancer and Blood Disorders Clinic, Louisville, KY, USA; 8Amgen Ltd., Uxbridge, Middlesex, UK and 9Amgen Inc., Thousand Oaks, CA, USA
ABSTRACT
Children with immune thrombocytopenia for ≥6 months completing a romiplostim study received weekly subcutaneous romiplostim (1-
9
10 μg/kg targeting platelet counts of 50-200x10 /L) in this extension
to examine romiplostim’s long-term safety and efficacy. Sixty-five children received romiplostim for a median of 2.6 years (range: 0.1-7.0 years). Median baseline age was 11 years (range: 3-18 years) and platelet count was 28x109/L (range: 2-458x109/L). No patient discontinued treatment for an adverse event. Median average weekly dose was 4.8 mg/kg (range: 0.1-10 mg/kg); median platelet counts remained >50x109/L, starting at week 2. Nearly all patients (94%) had ≥1 platelet response (≥50x109/L, no rescue medication in the previous 4 weeks), 72% had responded at ≥75% of visits, and 58% had responded at ≥90% of visits. Treatment-free response (platelets ≥50x109/L ≥24 weeks without immune thrombocytopenia treat- ment) was seen in 15 of 65 patients while withholding romiplostim doses. At onset of treatment-free response, the nine girls and six boys had a medi- an immune thrombocytopenia duration of four years (range: 1-12 years) and had received romiplostim for two years (range: 1-6 years). At last obser- vation, treatment-free responses lasted for a median of one year (range: 0.4- 2.1 years), with 14 of 15 patients still in treatment-free response. Younger age at first dose and platelet count >200x109/L in the first four weeks were associated with treatment-free responses. In this 7-year open-label exten- sion, three-quarters of the patients responded ≥75% of the time, and romi- plostim was well tolerated, with no substantial treatment-related adverse events. Importantly, 23% of children maintained treatment-free platelet responses while withholding romiplostim and all other immune thrombo- cytopenia medications for ≥6 months. (Registered at clinicaltrials.gov identifi- er: 01071954)
Introduction
Chronic immune thrombocytopenia (ITP) in children is an autoimmune disorder characterized by increased platelet destruction and suboptimal platelet production.1 Newly diagnosed and persistent ITP in children have high rates of spontaneous remission; only a small minority develop clinically severe chronic disease.2 However, these children often have very low platelet counts that are very difficult to treat, have an ongoing risk of intracranial hemorrhage and other bleeding, and have an impaired quality of life.3,4 There are few data on long-term improvement
Correspondence:
MICHAEL D. TARANTINO
mtarantino@ilbcdi.org
Received: July 20, 2018. Accepted: March 6, 2019. Pre-published: March 7, 2019.
doi:10.3324/haematol.2018.202283
Check the online version for the most updated information on this article, online supplements, and information on authorship & disclosures: www.haematologica.org/content/104/11/2283
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haematologica | 2019; 104(11)
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