FDA Approves Romiplostim for Paediatric Patients with Immune Thrombocytopenia

Approval is based on results from two double-blind placebo-controlled clinical trials

On 14 December 2018, the US Food and Drug Administration (FDA) approved romiplostim (NPLATE, Amgen Inc.) for paediatric 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 paediatric 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 randomised (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 enrolment were randomised (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 paediatric patients, the most common adverse reactions (≥ 25%) include contusion, upper respiratory tract infection, and oropharyngeal pain.

The recommended initial romiplostim dose for paediatric 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.

Full prescribing information for NPLATE is available here.

FDA granted this application orphan product designation.

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.