Evaluation of the US Oncology Network's recommended guidelines for therapeutic substitution with darbepoetin alfa 200 microg every 2 weeks in both naïve patients and patients switched from epoetin alfa.

STUDY OBJECTIVE

To evaluate the efficacy of darbepoetin alfa 200 microg subcutaneously every 2 weeks after therapeutic substitution for epoetin alfa.

DESIGN

Retrospective multicenter chart review.

SETTING

Three US Oncology-affiliated outpatient sites.

PATIENTS

Three hundred thirty anemic patients with nonmyeloid malignancies, of whom 174 had been treated previously with epoetin alfa (switched group) and 156 had not been treated recently with epoetin alfa (naive group).

INTERVENTIONS

Therapeutic substitution with darbepoetin alfa was started according to the US Oncology Pharmacy and Therapeutics Committee's recommended dosing guidelines: anemic patients with cancer received a starting dosage of darbepoetin alfa 200 microg every 2 weeks regardless of whether or not they had previously received epoetin alfa. Hematologic and darbepoetin alfa usage data were abstracted from consecutive medical records dated from May 2002-March 2003.

MEASUREMENTS AND MAIN RESULTS

Median exposure to darbepoetin alfa was 10 weeks (25th quartile 6 wks, 75th quartile 17 wks) and 10 weeks (25th quartile 5 wks, 75th quartile 18 wks) for the naive and switched groups, respectively. The week before the switch to darbepoetin alfa, the 174 patients receiving epoetin alfa were administered the following weekly doses: less than 40,000 U (9%), 40,000 U (50%), or 45,000-90,000 U (41%). Mean hemoglobin level increased from baseline (wk 0) in both the naive and switched groups. The proportion of patients receiving a red blood cell transfusion in the darbepoetin alfa treatment phase was low (15% in each group). No variation in transfusion rates was observed across weight categories in patients who received a fixed dosage of darbepoetin alfa. Darbepoetin alfa was well tolerated. A detailed usage algorithm was validated by these results and is being used in these three US Oncology-affiliated practices.

CONCLUSION

A darbepoetin alfa starting dosage of 200 microg subcutaneously every 2 weeks administered according to US Oncology-recommended dosing guidelines is effective in treating chemotherapy-induced anemia in both epoetin alfa-naive patients and those switched from epoetin alfa.