Background G-CSF biosimilars are an emerging class of biopharmaceutical agents that may become an interesting cost saving alternative to cope with the increasing burden of cancer. Frequently, these drugs are supported by limited clinical data at the time of approval, and it is necessary to add experience in daily clinical practice to demonstrate their equivalence.

Purpose To compare the effectiveness of biosimilar filgrastim (Zarzio) with original G-CSF (Granocyte and Neulasta) in febrile neutropenia (FN) prevention in breast cancer patients receiving docetaxel/doxorubicin/cyclophosphamide (TAC), and to analyse treatment patterns for these drugs.

Material and methods This was a comparative cohort study developed in a tertiary referral hospital with retrospective data collection (2012 to 2014). The analysis included patients with breast cancer that received FN primary prophylaxis with G-CSF during TAC treatment. Variables were extracted from the electronic database (Pharmatools) and the medical centre intranet which contain demographic data, diagnoses, treatment plans, medical histories, allergies, and laboratory and test results. Effectiveness of G-CSF was evaluated by FN incidence. Other parameters evaluated were: severe neutropenia (G3, G4 and FN) incidence and hospitalisations due to severe neutropenia. Data were analysed using each cycle as a unit of analysis. Continuous variables were assessed using the independent t test while categorical variables were compared using the χ2. All statistical analysis was performed using SPSS v.15.0, with a significance level of p < 0.05.

Results We identified 98 patients (97 females) representing 518 chemotherapy cycles (215 original G-CSF and 303 biosimilar G-CSF). The incidence of FN was similar in both groups, 3.7% in the original cohort versus 3.3% in the biosimilar cohort (p = 0.797). No statistically significant differences were found in severe neutropenia incidence (4.7% vs 6.3%) or hospitalisations due to this cause (3.3% vs 3.6%). In relation to treatment patterns of G-CSF, mean (SD) duration of Granocyte prophylaxis was 7.1 (1.9) days per cycle, 5.6 (1.4) days with Zarzio and 1 day with Neulasta (p < 0.001).

Conclusion No differences between original and biosimilar G-CSF effectiveness were detected. Zarzio was considered a lower cost alternative and equally as effective as its comparators in reducing FN incidence in breast cancer patients receiving TAC.

References and/or Acknowledgements Thanks to the Pharmacy Service.

No conflict of interest.