Clinical trial simulation of a 200-microg fixed dose of darbepoetin alfa in chemotherapy-induced anemia

Abstract

Our objective was to assess, using clinical trial simulation, the feasibility of a fixed 200-microg dose of darbepoetin alfa (Aranesp) administered every 2 weeks in chemotherapy-induced anemia. A pharmacokinetic/pharmacodynamic model was developed using clinical data from 547 cancer patients who received darbepoetin alfa at various doses and schedules. Monte Carlo simulations were performed for weight-based (3 microg/kg every 2 weeks) and fixed-dose (200 microg every 2 weeks) regimens and were compared with observed clinical data. Mean hemoglobin changes from baseline to end of treatment were +1.61 g/dL, +1.83 g/dL, and +1.79 g/dL for observed data, the weight-based simulation, and the fixed-dose simulation, respectively. The rates of required transfusions (hemoglobin < or = 8 g/dL) were also similar between groups. For patients between 45 and 95 kg (over 90% of the population), the impact of a fixed dose on mean hemoglobin change was negligible. There was a slight weight effect at body weight extremes (< 45 kg and > 95 kg). Clinical outcomes from simulations of weight-based andfixed dosing of darbepoetin alfa were similar to those of observed weight-based data. Given the weight distribution of a typical cancer population, the majority would be expected to benefit equally from weight-based and fixed-dose darbepoetin alfa in the amelioration of chemotherapy-induced anemia.