Efficacy and safety of balugrastim compared with pegfilgrastim in patients with breast cancer who are receiving chemotherapy.

Abstract

9125 Background: Patients receiving cancer chemotherapy are at an increased risk of neutropenia. Recombinant granulocyte colony stimulating factors (G-CSFs) have been developed to stimulate proliferation and differentiation of neutrophils. Pegfilgrastim is a pegylated recombinant G-CSF that allows for once-per-cycle dosing. Balugrastim is a long-acting G-CSF composed of a genetic fusion between recombinant human serum albumin and G-CSF. The objective of this study was to compare the efficacy and safety of balugrastim and pegfilgrastim in patients with histologically or cytologically confirmed breast cancer who were scheduled to receive doxorubicin and docetaxel. Methods: In this double-blind, randomized, active-comparator, noninferiority trial, patients with ≥1.5x109 neutrophils/L, and ≥100x109 platelets/L were randomly assigned to subcutaneous injections of balugrastim 40 mg (n=153) or pegfilgrastim 6 mg (n=151) with stratifications for weight, prior chemotherapy exposure, and global location. The primary efficacy endpoint was the duration of severe neutropenia (days with an absolute neutrophil count <0.5x109 cells/L) during the cycle 1 for the population of patients who did not have major protocol violations. Results: Mean duration of severe neutropenia in cycle 1 was 1.1 days in the balugrastim group and 1.0 days in the pegfilgrastim group (95% CI for difference between groups -0.13 to 0.37). Fifty-eight percent of patients in the balugrastim group and 59% in the pegfilgrastim group had severe neutropenia during cycle 1 (95% CI for difference between groups -11.98% to 10.41%). Two and 4 patients, respectively, had febrile neutropenia during cycle 1; no patients in either group had febrile neutropenia during cycles 2-4. Twenty percent of patients in the balugrastim group and 19% in the pegfilgrastim group had adverse events that the investigator considered to be related to study medication. Six and 7 patients, respectively, had serious adverse events. Conclusions: The results of this study support the noninferiority of balugrastim versus pegfilgrastim, demonstrating that both compounds have comparable efficacy. There were no unexpected safety events.