On December 21, 2017, the US Food and Drug Administration (FDA) granted regular approval to hydroxyurea (Siklos, Addmedica) to reduce the frequency of painful crises and the need for blood transfusions in pediatric patients from 2 years of age and older with sickle cell anemia with recurrent, moderate to severe painful crises.

This is the first FDA approval of hydroxyurea for use in pediatric patients with sickle cell disease.

Approval was based on data from an open-label, single-arm trial, the European Sickle Cell Disease Cohort study (ESCORT HU, NCT02516579), of 405 pediatric patients with sickle cell disease from 2-18 years of age, of which 141 had not been previously treated with hydroxyurea prior to enrollment. Among this pediatric population analyzable for efficacy (n = 141), Siklos use resulted in an increase in hemoglobin F. The percentage of patients with at least one vaso-occlusive episode, one episode of acute chest syndrome, one hospitalization due to sickle cell disease, or one blood transfusion decreased after 12 months of hydroxyurea treatment.

Most common adverse reactions to Siklos (incidence >10%) include infections and neutropenia.

The recommended initial dose of hydroxyurea is 20 mg/kg once daily.

FDA granted priority review and Orphan Drug designation to this application.