Effectiveness of cytopenia prophylaxis for different filgrastim and pegfilgrastim schedules in a chemotherapy mouse model

Markus Scholz¹, Manuela Ackermann², Frank Emmrich², Markus Loeffler¹, Manja Kamprad²

¹Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Haertelstrasse 16–18, 04107 Leipzig, Germany; ²Institute for Clinical Immunology and Transfusion Medicine, University of Leipzig, Johannisallee 30, 04103 Leipzig, Germany

Objectives: Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is widely used to treat neutropenia during cytotoxic chemotherapy. The optimal scheduling of rhG-CSF is unknown and can hardly be tested in clinical studies due to numerous therapy parameters affecting outcome (chemotherapeutic regimen, rhG-CSF schedules, individual covariables). Motivated by biomathematical model simulations, we aim to investigate different rhG-CSF schedules in a preclinical chemotherapy mouse model.

Methods: The time course of hematotoxicity was studied in CD-1 mice after cyclophosphamide (CP) administration. Filgrastim was applied concomitantly in a 2 × 3-factorial design of two dosing options (2 × 20 μg and 4 × 10 μg) and three timing options (directly, one, and two days after CP). Alternatively, a single dose of 40 μg pegfilgrastim was applied at the three timing options. The resulting cytopenia was compared among the schedules.

Results: Dosing and timing had a significant influence on the effectiveness of filgrastim schedules whereas for pegfilgrastim the timing effect was irrelevant. The best filgrastim and pegfilgrastim schedules exhibited equivalent toxicity. Monocytes dynamics performed analogously to granulocytes. All schedules showed roughly the same lymphotoxicity.

Conclusion: We conclude that effectiveness of filgrastim application depends heavily on its scheduling during chemotherapy. There is an optimum of timing. Dose splitting is better than concentrated applications. Effectiveness of pegfilgrastim is less dependent on timing.

Keywords: rhG-CSF, chemotherapy toxicity, mice, cyclophosphamide, cytopenia, neutropenia