Efficacy and safety of lipegfilgrastim compared with pegfilgrastim in patients with breast cancer who are receiving chemotherapy.
e19587 Background: Cancer chemotherapy frequently causes neutropenia, leading to an increased risk of infections and delays in subsequent chemotherapy treatments. Pegfilgrastim is a pegylated recombinant form of granulocyte colony stimulating factor (G-CSF) that extends the half-life and requires less frequent dosing than nonpegylated G-CSF. Lipegfilgrastim is a glycosylated and pegylated G-CSF. The objective of this study was to compare the efficacy and safety of lipegfilgrastim and pegfilgrastim in chemotherapy-naïve patients with breast cancer who are candidates to receive docetaxel/doxorubicin. Methods: In this double-blind, randomized, active-controlled, noninferiority trial, patients with high-risk stage II, III, or IV breast cancer and an absolute neutrophil count ≥1.5x109 cells/L were randomly assigned to lipegfilgrastim 6 mg (n=101) or pegfilgrastim 6 mg (n=101). Study medication was injected subcutaneously on day 2 of the chemotherapy cycle (4 cycles maximum). Primary efficacy endpoint was the duration of severe neutropenia (days with an absolute neutropenia count <0.5x109 cells/L) during cycle 1. Secondary endpoints included the incidence of febrile neutropenia. Efficacy analysis population included patients who were randomized but did not have major protocol violations. Results: Overall, 37%, 46%, and 17% of patients had stage II, III, and IV breast cancer, respectively. The mean duration of severe neutropenia in cycle 1 was 0.7 days in the lipegfilgrastim group and 0.8 days in the pegfilgrastim group (poisson regression least squares mean [95% CI] -0.218 [-0.498 to 0.062]). 56% and 49%, respectively, did not experience severe neutropenia in cycle 1. Three patients experienced febrile neutropenia; all were in the pegfilgrastim group during cycle 1. 28% of patients in the lipegfilgrastim group and 26% in the pegfilgrastim group had adverse events that the investigator considered to be related to study medication. Three and 7 patients, respectively had serious adverse events. Conclusions: The results of this study confirm that the efficacy of lipegfilgrastim is comparable with pegfilgrastim. No unexpected safety events were observed.