Guidelines for Complications of Cancer Treatment Vol VIII Part B

Darbopoietin Vs Epoetin Alfa: Is There anyDifference?Compared with Erythropoietin alfa, Darbopoietin has anincreased number of sialic-containing N-linked carbohydratechains, which renders it less susceptible to catabolism therebyincreasing its serum half-life 3-fold. Pooled data from 3 clinicaltrials in which 300 mcg of darbopoietin was given every 2weeks to patients undergoing multicycle chemotherapydemonstrated a baseline change in Hemoglobin >/= 2 g/dL in71% of the 115 patients included. [22] Similarly, in a dose-findingstudy, Darbopoietin was given as either a 3-mcg/kg or a 5-mcg/kg injection every 2 weeks, while EPO was given at adose of 40,000 units (increased to 60,000 U after 4 weekswhen Hemoglobin increase was < 1 g/dL). Patients whoachieved hematologic response were 66% and 84% for thetwo Darbopoietin doses respectively as compared to 63%response rate for epoetin alfa [22] .Although there are currently no published head-to-head studiescomparing EPO with darbepoetin alfa, a pilot study by Glaspyet al [23] explored the feasibility and safety of Darbopoietinalfa as a front loading dose (4.5mcg/kg/week for 4 weeks)followed by 3 different maintenance dosing (1.5, 2.25 and 4.5mcg/kg/week), against once-weekly EPO (40000 units/ weekincreased to 60000 units at 6 weeks) as an active control. Therewas a marked increase in Hemoglobin concentration notedearly in all the Darbopoietin arms with no decrease in efficacywhen frequency was reduced. However, the increase was stillsmaller than the mean change of 2 g/dl seen in previous trialswith erythropoietin alfa. The study though not powered todetect differences between treatment arms did however suggesta higher activity for Darbopoietin. [24,25]484