Safety and efficacy of pegfilgrastim in pediatric oncology patients: The M.D. Anderson Cancer Center experience

Abstract

8272 Background: The growth factor filgrastim (G-CSF) reduces the severity and duration of neutropenia in cancer patients. Due to its short half-life, it has to be injected daily, usually for 7–10 days, which is a special challenge in treating children. Pegfilgrastim, a pegylated form of G-CSF, has a long half-life and thus only has to be injected once per chemotherapy cycle. Data on the use of pegfilgrastim in children is limited. Therefore we evaluated the safety and efficacy of pegfilgrastim in children. Methods: To date, we have retrospectively reviewed the charts of 21 pediatric patients (12 males, ages 4–20, median 13 yrs) with various cancers (19 solid tumors and 2 lymphomas) who received pegfilgrastim. All patients had life expectancy > 6 weeks and baseline lab values acceptable to receive chemotherapy. A total of 101 doses (median/patient 5, range 2–9) of pegfilgrastim were administered (98% 24–72 hours post-chemotherapy). Patients ≥ 45 kg received 6 mg each (44 doses), and patients < 45 kg received an average dose of 110 mcg/kg (57 doses). We evaluated the efficacy [measured by total white blood cell (WBC) recovery] and safety [measured by adverse drug reactions (ADRs)] of pegfilgrastim in these patients. Results: Of the 101 pegfilgrastim doses, 82 were followed by grade 3 or 4 neutropenia [absolute neutrophil count (ANC) < 1 x 109/L], 13 were not, and six could not be evaluated because of infrequent clinic visits. For the doses involving neutropenia, the average time to achieving an ANC ≥ 1 x 109/L was 10 days. For the 95 evaluable doses, the average time to peak WBC count was 12.5 days, and 25 admissions for febrile neutropenia (grade 3 or 4) occurred prior to WBC recovery. Identifiable ADRs included: 4 episodes of bone/muscular pain, 1 episode of chills, and 28 episodes of leukocytosis (8 cases of WBC > 2 times upper limit of normal for age). No reports of organ dysfunction were noted. Conclusions: Pegfilgrastim appears to be a safe and effective alternative to G-CSF in children with cancer, and we continue to use this agent at our center. No significant financial relationships to disclose.