December 14, 2018
On December 14, 2018, the Food and Drug Administration approved romiplostim (NPLATE, Amgen Inc.) for pediatric patients 1 year of age and older with immune thrombocytopenia (ITP) 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 ITP for at least 6 months duration. In one study (NCT01444417), patients whose disease was refractory or relapsed after at least one prior ITP therapy were randomized (2:1) to receive romiplostim (n=42) or placebo (n=20). 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 (10%) on the placebo arm. Overall platelet response, defined as a durable or a 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 three endpoints were statistically significant, with p-values all less than 0.05.
In the other study (NCT00515203), patients diagnosed with ITP at least 6 months prior to enrollment were randomized (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% CI: 64%, 99%). No patient receiving placebo achieved either endpoint.
In pediatric patients, the most common adverse reactions (≥ 25%) include contusion, upper respiratory tract infection, and oropharyngeal pain.
The recommended initial romiplostim dose for pediatric patients is 1 mcg/kg based on actual body weight and administered as a weekly subcutaneous injection. Dose should be adjusted in increments of 1 mcg/kg until the patient achieves a platelet count ≥ 50 x 109/L. Reassessment of body weight is recommended every 12 weeks.
FDA granted this application orphan product designation. A description of FDA expedited programs is in the Guidance for Industry: Expedited Programs for Serious Conditions-Drugs and Biologics.
Healthcare professionals should report all serious adverse events suspected to be associated with the use of any medicine and device to FDA’s MedWatch Reporting System by completing a form online at http://www.fda.gov/medwatch/report.htm, by faxing (1-800-FDA-0178) or mailing the postage-paid address form provided online, or by telephone (1-800-FDA-1088).