Treatment patterns and outcomes in the prophylaxis of chemotherapy-induced (febrile) neutropenia with biosimilar filgrastim (the MONITOR-GCSF study)

PURPOSE: The purpose of this study is to examine the real-world treatment patterns and outcomes of chemotherapy-induced (febrile) neutropenia (chemotherapy-induced (CIN)/febrile neutropenia (FN)) prophylaxis with biosimilar filgrastim (Zarzio®).

METHODS: MONITOR-GCSF is an international (12 countries), multi-center (140), prospective (max. six cycles), observational, open-label, pharmaco-epidemiologic study of cancer patients (n = 1447) treated with myelosuppressive chemotherapy across a total of 6,213 cycles and receiving prophylaxis with Zarzio®. Data were analyzed using both the patient and cycle as unit of analysis.

RESULTS: Most (72.3 %) received primary prophylaxis; dosed mainly (53.2 %) at 30 MIU but differentiated by weight, chemotoxicity, and tumor type; and mainly (53.2 %) initiated in the 24-72h post-chemotherapy window but differentiated by prophylaxis type, tumor type, and chemotoxicity and for modal/median duration of 5 days. Relative to European Organisation for Research and Treatment of Cancer (EORTC) guidelines, 56.6 % were correctly prophylacted, 17.4 % under-prophylacted, and 26.0 % over-prophylacted. The following incidence rates were recorded: CIN grade 4 13.2 % of patients and 3.9 % of cycles, FN 5.9 % of patients and 1.4 % of cycles, CIN/FN-related hospitalizations 6.1 % of patients and 1.5 % of cycles, CIN/FN-related chemotherapy disturbances 9.5 % of patients and 2.8 % of cycles, and composite outcomes index 22.3 % of patients and 6.7 % of cycles. Rates varied by type of prophylaxis and tumor, chemotoxicity, initiation day, and prophylaxis duration. There were 1834 musculoskeletal events with 24.7 % of patients reporting bone pain of any grade (mostly mild to moderate), and 148 adverse drug reactions, including 4 serious, were recorded in 76 patients.

CONCLUSIONS: The clinical and safety outcomes are well within the range of historically reported data for originator filgrastim underscoring the clinical effectiveness and safety of biosimilar filgrastim in daily clinical practice.