The Food and Drug Administration (FDA) approved romiplostim (Nplate), the first platelet producer for the treatment of adult chronic ITP (immune thrombocytopenic purpura).
FDA based its approval on two randomized clinical trials of about 125 patients who had received at least one prior ITP treatment. One study enrolled patients who still had their spleen, the other enrolled patients who did not.
During 6 months of treatment, patients who received Nplate had significantly higher platelet counts and maintained those higher counts, compared to those who did not receive the drug. The response to Nplate was higher in those patients who still had their spleen than in those patients who had undergone a splenectomy. In those patients who did not receive Nplate, only one experienced a sustained increase in platelet counts.
Amgen’s Nplate is currently not recommended in patients with myelodysplasia. In a study of 44 patients who had myelodysplasia and received Nplate, 4 patients developed leukemia. Further clinical trials in patients with predisposing conditions for leukemia will be needed to determine whether the development of leukemia may relate to the use of Nplate.
A Risk Evaluation and Mitigation Strategy (REMS) will be done by FDA to determine if NPlate’s risks outweigh its benefits. The REMS will require that all prescribers and patients enroll in a special program to track the long term safety of Nplate therapy.