Efficacy of pegfilgrastim and darbepoetin alfa as hematopoietic support for dose-dense every-2-week adjuvant breast cancer chemotherapy

Abstract

Purpose: Dose-dense, every-2-week adjuvant chemotherapy using doxorubicin/cyclophosphamide (AC; 60/600 mg/m2 every 2 weeks x four cycles) followed by paclitaxel (175 mg/m2 every 2 weeks x four cycles), requiring filgrastim on days 3 through 10 of each cycle has been shown to improve survival compared with every-3-week treatment schedules but is associated with greater risk of RBC transfusion (13%). The role of long-acting hematopoietic growth factors in facilitating every-2-week chemotherapy and minimizing hematologic toxicity has not been established.

Patients and methods: Women with stage I to III breast cancer received dose-dense AC --> paclitaxel as neoadjuvant or adjuvant chemotherapy. Patients received pegfilgrastim 6 mg subcutaneous (SQ) on day 2 of each cycle. Darbepoetin alfa was initiated at 200 microg SQ every 2 weeks for hemoglobin < or = 12 g/dL, and administered thereafter, according to a preplanned algorithm. The primary end points were to evaluate the percentage of patients with febrile neutropenia and the percentage of patients requiring RBC transfusion.

Results: Among 135 women treated on this single arm study, there were two cases of febrile neutropenia (incidence 1.5%). No patients received RBC transfusion. Darbepoetin alfa therapy was initiated in 92% of patients. The modest leukocytosis seen during paclitaxel cycles was attributable, in part, to corticosteroid premedication. Other toxicity and dose-delivery were similar to dose-dense AC --> paclitaxel in Cancer and Leukemia Group B 9741.

Conclusion: Pegfilgrastim and darbepoetin alfa are effective and safe in facilitating every-2-week AC --> paclitaxel, minimizing rates of febrile neutropenia and RBC transfusion.