Effectiveness of biosimilar filgrastim vs. original granulocyte colony-stimulating factors in febrile neutropenia prevention in breast cancer patients.

PURPOSE: The purpose of this study is to describe the effectiveness of biosimilar filgrastim and original granulocyte colony-stimulating factors (G-CSFs), lenograstim and pegfilgrastim, in febrile neutropenia (FN) prevention in breast cancer patients receiving docetaxel/doxorubicin/cyclophosphamide (TAC) as adjuvant/neoadjuvant treatment and to analyze their treatment patterns.
METHODS: A pharmacoepidemiology cohort study was developed in a university hospital (with 23 healthcare centers) with retrospective data collection (2012-2014). Effectiveness of G-CSFs was assessed by the FN incidence. Other parameters analyzed were as follows: moderate and severe neutropenia incidence, neutropenia-related hospitalizations, dosage, and duration. Data was analyzed using each cycle as a unit of analysis.
RESULTS: We identified 98 patients representing 518 chemotherapy cycles, 215 with original G-CSFs (35 lenograstim and 180 pegfilgrastim) and 303 with biosimilar filgrastim. The FN incidence was similar in both groups (3.7% original vs. 3.3% biosimilar; p = 0.79). No statistically significant differences were found in moderate and severe neutropenia incidence (4.7 vs. 6.3%; p = 0.43) or neutropenia-related hospitalizations (3.3 vs. 3.6%; p = 0.19). When the three drugs were evaluated separately, a higher FN incidence was observed with lenograstim than with pegfilgratim or biosimilar (p = 0.024). The dosage and duration of biosimilar were lower than lenograstim (4.9 vs. 5.7 μg/kg/day; 5 vs. 7 days; p < 0.001).
CONCLUSION: An abbreviated 5-day course of biosimilar filgrastim provided optimal primary prophylaxis against FN post-chemotherapy TAC in patients with breast cancer. The clinical relevance of the highest FN incidence in the lenograstim cohort needs further attention.