Evaluation of efficacy and safety of pegfilgrastim when given less than two weeks from dose-dense chemotherapy regimens.

Introduction: In clinical practice, waiting 14 days between the administration of pegfilgrastim and subsequent chemotherapy cycle (as recommended by the prescribing information) is sometimes not feasible with multi-cycle dose-dense regimens. This study evaluated the practice related to the use of pegfilgrastim in oncology patients at a multi-hospital health system.

Methods: Patients who received pegfilgrastim as primary prophylaxis following dose-dense chemotherapy scheduled every 14 days were included. The primary endpoint was the impact of <14 elapsed days between pegfilgrastim administration and next chemotherapy cycle on the change in mean absolute neutrophil counts (ANC). A generalized linear mixed-effects model with fixed effects for pegfilgrastim delivery method, elapsed days between pegfilgrastim and chemotherapy (fixed categorical effect for 12, 13, 14 days), and ANC at subsequent cycle was fitted to the change in ANC between chemotherapy cycles.

Results: One hundred and sixty four patients with breast cancer who received pegfilgrastim support for dose dense doxorubicin and cyclophosphamide (ddAC) qualified for the model. The mean age was 52 ± 12 years. Eighty-eight percent received pegfilgrastim on-body injector while 13% received pegfilgrastim injection. The mean number of elapsed days between pegfilgrastim and subsequent chemotherapy was 13 ± 0.5 days. The method of pegfilgrastim delivery and elapsed days between pegfilgrastim and chemotherapy administration had no significant effect on the change in ANC (p = 0.8663 and p = 0.8434 respectively); however, patient's age (p = 0.0125) had a significant effect on the change in ANC.

Conclusion: The study findings suggest safety and efficacy when chemotherapy is administered 12-14 days from pegfilgrastim.