BACKGROUND: Filgrastim is an effective granulocyte colony-stimulating factor 
(G-CSF) used to reduce periods of neutropenia and the risk of infection after 
chemotherapy courses. Pegfilgrastim is a pegylated filgrastim with a longer 
plasma half-life that is administered once per cycle.
OBJECTIVE: The aim of this study was to compare the efficacy of pegfilgrastim 
and filgrastim administered after chemotherapy in children with Ewing sarcoma.
METHODS: We performed a retrospective chart review of pediatric patients with 
Ewing sarcoma. Every patient received both types of G-CSF in different treatment 
courses of chemotherapy, which consisted of vincristine, ifosfamide, 
doxorubicin, and etoposide (VIDE); vincristine, actinomycin D, and ifosfamide 
(VAI); or vincristine, actinomycin D, and cyclophosphamide (VAC). A single 
injection of pegfilgrastim 100 microg/kg SC or a daily injection of filgrastim 5 
to 10 microg/kg SC was administered 48 to 72 hours after the completion of 
chemotherapy. The following data were collected from the medical charts: 
proportion of chemotherapy courses with grade 4 neutropenia, duration of grade 4 
neutropenia, proportion with severe neutropenia, duration of severe neutropenia, 
proportion with febrile neutropenia, duration of antibiotic treatment, duration 
of hospitalization, and percentage of patients receiving transfusion. Grade 4 
neutropenia was defined as an absolute neutrophil count of <500 x 10(9)/L; 
severe neutropenia was defined as a count of <200 x 10(9)/L. Adverse events were 
collected from the medical charts.
RESULTS: Twenty children were included (13 girls and 7 boys). The patients' 
median age was 12.8 years (range, 9-17 years) and median weight was 45.2 kg 
(range, 28-90 kg). A total of 178 chemotherapy courses (108 VIDE; 70 VAI or VAC) 
were administered and evaluated, including 134 courses with pegfilgrastim and 44 
courses with filgrastim. Considering all types of chemotherapy combined, those 
courses in which pegfilgrastim was used were associated with a significantly 
lower incidence of severe neutropenia (0.21 vs 0.85; P = 0.03), a shorter 
duration of severe neutropenia (0.49 vs 2.36 days; P = 0.01), and a shorter 
duration of antibiotic treatment (1.07 vs 4.22 days; P = 0.03) compared with 
courses treated with filgrastim. No statistically significant differences were 
observed for the proportion and duration of grade 4 neutropenia, proportion of 
febrile neutropenia, duration of hospitalization, or red blood cell and platelet 
transfusions. Adverse effects were few and comparable between pegfilgrastim and 
filgrastim.
CONCLUSIONS: In this retrospective chart review of children with Ewing sarcoma, 
using pegfilgrastim after chemotherapy courses was associated with significantly 
reduced frequency and shorter duration of severe neutropenia compared with those 
courses followed by filgrastim. Randomized controlled trials are needed to 
confirm these preliminary observations.