Efficacy and Safety of Balugrastim Compared With Pegfilgrastim in Patients With Breast Cancer Receiving Chemotherapy

Background Recombinant granulocyte colony-stimulating factors (G-CSFs) reduce the incidence and duration of chemotherapy-induced neutropenia and febrile neutropenia when given as adjunct therapy to patients receiving myelosuppressive chemotherapy. Balugrastim is a long-acting G-CSF composed of a genetic fusion between recombinant human serum albumin and G-CSF. We compared the efficacy and safety of balugrastim and pegfilgrastim, a long-acting pegylated recombinant G-CSF, in patients with breast cancer who were scheduled to receive chemotherapy. Patients and Methods In this double-blind randomized phase III trial, patients with ≥ 1.5 × 109 neutrophils/L were randomly assigned to subcutaneous injections of balugrastim 40 mg (n = 153) or pegfilgrastim 6 mg (n = 151). The primary efficacy end point was the duration of severe neutropenia (DSN) (days with an absolute neutrophil count [ANC] < 0.5 × 109 cells/L) during cycle 1. Efficacy analyses were performed in the per-protocol (PP) population. In a separate open-label single-arm study, newly recruited patients (n = 77) received balugrastim 40 mg and were included in the safety analysis. Results The mean DSN in cycle 1 was 1.1 days in the balugrastim group and 1.0 days in the pegfilgrastim group (95% confidence interval [CI], −0.13-0.37). Two and 4 patients, respectively, had febrile neutropenia during cycle 1. Twenty percent of patients in the balugrastim group and 19% in the pegfilgrastim group had adverse events (AEs) considered to be related to study medication; 3.9% and 4.7% of patients, respectively, experienced serious AEs. Conclusions This study demonstrates the comparable safety and efficacy profile of balugrastim and pegfilgrastim and the noninferiority of balugrastim for reduction in DSN. There were no unexpected safety events.