On December 14, 2018, the U.S. Food and Drug Administration (FDA) approved romiplostim (Nplate) for pediatric patients at least 1 year old with immune thrombocytopenia for at least 6 months who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. Approval was based on two double-blind placebo-controlled clinical trials in pediatric patients 1 year and older with immune thrombocytopenia for at least 6 months’ duration.
Trials Supporting Approval
In one study (ClinicalTrials.gov identifier NCT01444417), patients whose disease was refractory or relapsed after at least one prior immune thrombocytopenia therapy were randomly assigned (2:1) to receive romiplostim (n = 42) or placebo (n = 20). A durable platelet response (at least 6 weekly platelet counts ≥ 50 × 109/L during weeks 18 through 25 of treatment) was achieved in 22 patients (52%) who received romiplostim and 2 patients (10%) on the placebo arm. Overall platelet response—defined as a durable or transient platelet response—was achieved in 30 (71%) and 4 (20%) patients, respectively. Patients who received romiplostim had platelet counts ≥ 50 x 109/L for a median of 12 weeks, compared to 1 week in patients who received placebo. The results for all 3 endpoints were statistically significant, with P values all less than .05.
In the other study (ClinicalTrials.gov identifier NCT00515203), patients diagnosed with immune thrombocytopenia at least 6 months prior to enrollment were randomly assigned (3:1) to receive romiplostim (n = 17) or placebo (n = 5). Fifteen patients who received romiplostim achieved a platelet count ≥ 50 x 109/L for 2 consecutive weeks and an increase in platelet count of ≥ 20 × 109/L above baseline for 2 consecutive weeks during the treatment period (88%, 95% confidence interval = 64%–99%). No patient receiving placebo achieved either endpoint.
In pediatric patients, the most common adverse reactions (≥ 25%) included contusion, upper respiratory tract infection, and oropharyngeal pain.
The recommended initial romiplostim dose for pediatric patients is 1 μg/kg based on actual body weight and administered as a weekly subcutaneous injection. Dose should be adjusted in increments of 1 μg/kg until the patient achieves a platelet count ≥ 50 x 109/L. Reassessment of body weight every 12 weeks is recommended.
The FDA granted this application Orphan Drug designation. View the full prescribing information for romiplostim.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.