Brito, M., Esteves, S., Andre, R., Isidoro, M., & Moreira, A. (2016). Comparison of effectiveness of biosimilar filgrastim (Nivestim), reference Amgen filgrastim and pegfilgrastim in febrile neutropenia primary prevention in breast cancer patients treated with neo(adjuvant) TAC: A non-interventional cohort study. Supportive Care in Cancer, 24, 597–603. 

To compare the effectiveness of a new biosimilar colony-stimulating factor (CSF) compared to reference CSF medications

Data were obtained from medical records in a tertiary cancer center for women with breast cancer who had received TAC chemotherapy. The febrile neutropenia management protocol was the same in all cohorts. Outcomes were compared across cohorts of patients who had received the biosimilar filgrastim, reference filgrastim, and pegfilgrastim.

• N = 420
• MEDIAN AGE = 50 years 
• AGE RANGE = 25–76 years
• FEMALES: 100%
• KEY DISEASE CHARACTERISTICS: All women had breast cancer.

• SITE: Single site  
• SETTING TYPE: Not specified  
• LOCATION: Portugal

• PHASE OF CARE: Active antitumor treatment

• Retrospective cohort comparison

• Febrile neutropenia (FN) defined at body temperature ≥ 38 C and ANC ≤ 500 cell/mcl
• ANC
• FN-related treatment delays, reductions, or terminations

FN episode rates were 16%, 9%, and 16% in the reference filgrastim, pegfilgrastim, and biosimilar groups respectively. ANC at the time of FN diagnosis was lower in the biosimilar group in comparison with reference filgrastim (p = 0.015), and FN episodes were more frequent in the biosimilar group compared to both other groups (p ≤ 0.02). There were more chemotherapy delays in the biosimilar group compared with pegfilgrastim (p = 0.04). There were no other differences between groups.

Findings suggest the need for ongoing studies to determine comparative efficacy of this biosimilar CSF for prevention of febrile neutropenia and related complications in patients receiving cancer treatment.

• Baseline sample/group differences of import
• Risk of bias (no blinding)
• Risk of bias (no random assignment)
• Key sample group differences that could influence results
• There were differences among cohorts in age, extent of disease, and use of antibiotic prophylaxis, which could have influenced results.

There are a growing number of biosimilar CSF agents being produced, and it is not yet clear if there are important clinical differences in bioavailability and activity in the clinical setting. Nurses should be aware of patients who are receiving biosimilar agents and monitor them for signs of FN or infection. Ongoing research is needed to determine safety and efficacy of these newer CSF agents over time.