Pharmacokinetic evaluation of darbepoetin alfa for the treatment of pediatric patients with chemotherapy-induced anemia

Background Cancer patients undergoing chemotherapy often develop anemia, which can increase the risk for transfusions and fatigue. The recombinant erythropoiesis‐stimulating agent darbepoetin alfa can effectively treat chemotherapy‐induced anemia (CIA) in adults, but limited data are available regarding its use in pediatric cancer patients. The goals of this phase 1, open‐label, uncontrolled study were to assess the pharmacokinetic profile and safety of darbepoetin alfa in pediatric patients with CIA. Procedure Pediatric patients with nonmyeloid malignancies and CIA received up to six doses of darbepoetin alfa 2.25 mcg/kg subcutaneously. After the first dose, the pharmacokinetic properties of darbepoetin alfa were assessed during a 14‐day sampling period. All subsequent doses were given weekly with predose blood samples collected before study drug administration. Results After a single dose of darbepoetin alfa, the mean (SD) peak serum concentration was 10.5 (3) ng/ml, and the median time to peak concentration was 71.4 hr. Darbepoetin alfa exhibited a mean (SD) terminal half‐life of 49.4 (32) hr. Upon repeated weekly administration, no evidence of darbepoetin alfa accumulation was observed though there was high intra‐ and inter‐individual variability. In addition, darbepoetin alfa was well tolerated; some study patients experienced increases in hemoglobin. Conclusions The pharmacokinetic profile of darbepoetin alfa indicated that it was slowly absorbed and exhibited a long terminal half‐life in these pediatric study patients with CIA. Pediatr Blood Cancer 2007;49:687–693. © 2006 Wiley‐Liss, Inc.