OBJECTIVES

: Despite the demonstrated efficacy and safety of biosimilar filgrastim, limited studies investigated the outcomes of switching between original and biosimilar brands. Our study aimed to assess the effectiveness and safety of filgrastim switching strategy.

METHODS

: This is a cross sectional retrospective cohort study. All adult cancer patients who required primary prophylaxis between 2014 and 2016 were identified. Cohort1: patients who used biosimilar filgrastim. Cohort 2: patients who used original filgrastim. Cohort 3: the switch population. Primary endpoint was: the incidence of febrile neutropenia. The secondary end points were: incidence of adverse drug reactions, incidence of admission due to febrile neutropenia and mean hospitalization length of stay.

RESULTS

: A total of 282 patients were identified. Cohort 1 (n=156), cohort 2 (89) and cohort 3 (n=37). Sixty percent of the patients were males. The mean age of patients was 47 ± 16.6 years. Forty nine percent of the patients had solid tumors and 51% had hematological malignancy. The incidence of febrile neutropenia was 10% in cohort 1, 15% in cohort 2 and 20% in cohort 3. Cohort 3 was associated with the highest percentage of febrile neutropenia that resulted in admission (15.6%) followed by cohort 1 (7.2%) and cohort 2 (12.6%). There was no statistically significant difference among the three cohorts in febrile neutropenia incidence (p=0.231) nor in admission incidence (p=0.212). There was a statistically significant difference in the mean duration of hospitalization between the three cohorts (p=0.0125). Cohort 1 (5.4 days, 95%CI: 1.4, 9.3), cohort 2 (6.4 days, 95%CI: 4.6, 8.2), and cohort 3 (7 days, 95%CI: 1.5, 12.5). There was no statically significant difference in ADRs incidence among the three cohorts (p=0.636).

CONCLUSIONS

: Filgrastim switching strategy is considered to have comparable effectiveness and safety outcomes relative to using original filgrsatim or biosimilar filgrastim.