Colony-Stimulating Factors for Febrile Neutropenia

Responses of the Authors:

Ishiguro and Toi and Kelly et al. question the wisdom of universal adherence to the 6-mg, fixed-dose formulation of pegfilgrastim currently approved by the Food and Drug Administration. Citing the pharmacokinetic data and preliminary clinical data, Ishiguro and Toi suggest that the most appropriate dose in Japanese patients should be 3.6 mg per cycle of chemotherapy and not the currently approved dose of 6 mg per cycle. Kelly et al. justifiably raise the issue of costs associated with the administration of CSF. They cite a small, nonrandomized, preliminary study suggesting that half-dose pegfilgrastim may be as effective as the standard 6-mg dose and potentially associated with less pain. Although we are sympathetic to these arguments, we also think that larger and more definitive studies should be conducted before the current package label is changed.

Buti et al. raise the issue of discrepancy in the literature, with some meta-analyses showing no effect of CSF on rates of infection-related death and overall survival, whereas others apparently do. Many factors can lead to discordant meta-analyses,1 the most common being the number and type of the studies selected for the meta-analysis, as Buti and colleagues indicate. The studies by Kuderer et al.2 and Lyman et al.3 showing that the use of CSF is associated with reduced mortality were more selective in scope and included far fewer patients and studies than did more comprehensive meta-analyses showing no such association in the context of either prophylaxis4 or treatment.5

Carton et al. outline a rare, but important, complication related to the management of breast cancer during pregnancy and provide their rationale for why the use of CSF should be avoided in pregnancy.

Benjamin Djulbegovic, M.D., Ph.D.
University of South Florida, Tampa, FL

LeAnn B. Norris, Pharm.D.
Charles L. Bennett, M.D., Ph.D.
University of South Carolina, Columbia, SC

Read More: GCSF

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