A Phase III Study of Balugrastim Versus Pegfilgrastim in Breast Cancer Patients Receiving Chemotherapy With Doxorubicin and Docetaxel

Objectives. This study aimed to evaluate the efficacy and safety of once-per-cycle balugrastim versus pegfilgrastim for neutrophil support in breast cancer patients receiving myelosuppressive chemotherapy. Methods. Breast cancer patients (n=256) were randomized to 40 or 50 mg of subcutaneous balugrastim or 6 mg of pegfilgrastim approximate to 24 hours after chemotherapy (60 mg/m(2) doxorubicin and 75 mg/m(2) docetaxel, every 21 days for up to 4 cycles). The primary efficacy parameter was the duration of severe neutropenia (DSN) in cycle 1. Secondary parameters included DSN (cycles 2-4), absolute neutrophil count (ANC) nadir, febrile neutropenia rates, and time to ANC recovery (cycles 1-4). Safety, pharmacokinetics, and immunogenicity were assessed. Results. Mean cycle 1 DSN was 1.0 day with 40 mg of balugrastim, 1.3 with 50 mg of balugrastim, and 1.2 with pegfilgrastim (upperlimit of 95% confidence intervals for between-group DSN differences was,1.0 day for both balugrastim doses versus pegfilgrastim). Between-group efficacy parameters were comparable except for time to ANC recovery in cycle 1 (40 mg of balugrastim, 2.0 days; 50mg of balugrastim, 2.1; pegfilgrastim, 2.6). Median terminal elimination half-life was approximate to 37 hours for 40 mg of balugrastim, approximate to 36 for 50 mg of balugrastim, and approximate to 45 for pegfilgrastim. Antibody response to balugrastim was low and transient, with no neutralizing effect. Conclusion. Once-per-cycle balugrastim is not inferior to pegfilgrastim in reducing cycle 1 DSN in breast cancer patients receiving chemotherapy; both drugs have comparable safety profiles.