The effect of filgrastim or pegfilgrastim on survival outcomes of patients with cancer receiving myelosuppressive chemotherapy

Abstract

Background: Primary prophylaxis with granulocyte colony-stimulating factor (G-CSF) is associated with higher chemotherapy relative dose intensity, which may lead to improved outcomes; however, the association between G-CSF primary prophylaxis and overall survival (OS) is not well characterized. This study assessed the effect of G-CSF primary prophylaxis on patient outcomes in randomized, controlled, registrational clinical trials of filgrastim and pegfilgrastim.

Patients and methods: Three placebo-controlled and two non-inferiority clinical trials of filgrastim and/or pegfilgrastim in patients receiving myelosuppressive chemotherapy for lung, breast, or colorectal cancer were included. The median OS, 6- and 12-month survival rates, and hazard ratios [HRs; unadjusted Cox model with 95% confidence intervals (CIs)] were estimated for patients receiving ≥1 dose of filgrastim, pegfilgrastim, or placebo. Comparisons were based on a log-rank test. A fixed-effect meta-analysis assessed the effect of primary prophylaxis with filgrastim/pegfilgrastim on OS in the placebo-controlled trials.

Results: In patients with lung cancer receiving filgrastim versus placebo, the median OS was 14.1 versus 11.1 months (HR, 0.81; 95% CI 0.48-1.35; P = 0.412); in patients who crossed over to filgrastim from placebo after cycle 1, the median OS was 16.9 months (HR, 0.75; 95% CI 0.43-1.28; P = 0.286). The median OS was inestimable in at least one treatment arm in the other studies because of the small number of OS events. Where estimable, 6- and 12-month survival rates were generally greater among patients receiving filgrastim/pegfilgrastim versus placebo. In the meta-analysis of placebo-controlled studies comparing G-CSF primary prophylaxis with placebo in the as-treated analysis sets, the HR (95% CI) for OS was 0.77 (0.58-1.03).

Conclusions: In this retrospective analysis, OS point estimates were greater among patients receiving filgrastim versus placebo, but the differences were not statistically significant. Further studies evaluating patient outcomes with G-CSF prophylaxis are warranted.

Clinical trial registration: NCT00035594, NCT00094809.

Keywords: G-CSF; filgrastim; neutropenia; overall survival; pegfilgrastim.

© The Author 2015. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For permissions, please email: journals.permissions@oup.com.