Clemons, M., Fergusson, D., Simos, D., Mates, M., Robinson, A., Califaretti, N., Zibdawi, L., Bahl, M., Raphael, J., Ibrahim, M.F.K., Fernandes, R., Pitre, L., Aseyev, O., Stober, C., Vandermeer, L., Saunders, D., Hutton, B., Mallick, R., Pond, G.R., and Awan, A.
The optimal duration of filgrastim as primary febrile neutropenia (FN) prophylaxis in early breast cancer patients is unknown, with 5, 7 or 10 days being commonly prescribed. This trial evaluates whether 5 days of filgrastim was non-inferior to 7/10 days. In this randomised, open-label trial, early breast cancer patients who were to receive filgrastim as primary FN prophylaxis were randomly allocated to 5 versus 7 versus 10 days of filgrastim for all chemotherapy cycles. A protocol amendment in November 2017 allowed subsequent patients (N = 324) to be randomised to either 5 or 7/10 days. The primary outcome was a composite of either FN or treatment-related hospitalisations. Secondary outcomes included chemotherapy dose reductions, delays and discontinuations. Analyses were carried out by per protocol (primary) and intention-to-treat, and the non-inferiority margin was set at 3% for the risk of having FN and/or hospitalisation per cycle of chemotherapy. Patients (N = 466) were randomised to receive 5 (184, 39.5%), or 7/10 (282, 60.5%) days of filgrastim. In our primary analysis, the difference in risk of either FN or treatment-related hospitalisation per cycle was −1.52% [95% confidence interval (CI): −3.22% to 0.19%] suggesting non-inferiority of a 5-day filgrastim schedule compared with 7/10-days. The difference in events per cycle for FN was 0.11% (95% CI: −1.05 to 1.27) while for treatment-related hospitalisations it was −1.68% (95% CI: −2.73% to −0.63%). The overall proportions of patients having at least one occurrence of either FN or treatment-related hospitalisation were 11.8% and 14.96% for the 5- and 7/10-day groups, respectively (risk difference: −3.17%, 95% CI: −9.51% to 3.18%). Five days of filgrastim was non-inferior to 7/10 days. Given the cost and toxicity of this agent, 5 days should be considered standard of care. NCT02428114 and NCT02816164. • Multicentre randomised trial of 466 breast cancer patients compared schedules of filgrastim administration. • Provides real-world data showing filgrastim use beyond 5 days did not significantly improve co-primary or secondary outcomes. • 5 days of filgrastim should be considered the standard of care. [ABSTRACT FROM AUTHOR]