The Food and Drug Administration (FDA) has approved Nplate (romiplostim; Amgen) for use in pediatric patients aged ≥1 year with immune thrombocytopenia (ITP) for ≥6 months who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. Previously, Nplate was approved for use in patients aged ≥18 years.

The expanded approval was supported by data from 2 double-blind, placebo-controlled trials in patients aged ≥1 year with ITP for at least 6 months. One study (NCT01444417) randomized 62 patients with refractory or relapsed disease after ≥1 prior ITP therapy to receive either romiplostim or placebo. The data showed durable platelet response (≥6 weekly platelet counts ≥50 x 109/L during weeks 18-25) was seen in 22 patients in the romiplostim arm vs 2 patients in the placebo arm. Overall platelet response was observed in 30 patients in the romiplostim arm vs 4 patients in the placebo arm. In addition, romiplostim-treated patients had platelet counts ≥50 x 109/L for median 12 weeks vs 1 week in placebo-treated patients. All endpoints were statistically significant (all P <.05). 

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The second study (NCT00515203) randomized 22 patients with ITP for ≥6 months to receive either romiplostim or placebo. In the romiplostim group, 15 of 17 patients achieved a platelet count ≥50 x 109/L for 2 consecutive weeks and an increase in platelet count of ≥20 x 109/L above baseline for 2 consecutive weeks during the treatment phase (88%, 95% CI, 64%, 99%). No patients in the placebo group achieved either endpoint. 

Contusion, upper respiratory tract infection, and oropharyngeal pain were the most frequent adverse events (occurring in ≥25%). 

Nplate, a thrombopoietin receptor agonist, is available as 250mcg and 500mcg strength vials for subcutaneous (SC) injection after reconstitution. 

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