Effect of concomitant use of G-CSF and myelosuppressive chemotherapy on bone marrow and peripheral granulocytes in a mouse model.

Granulocyte-colony stimulating factor (G-CSF) stimulates bone marrow progenitor cell proliferation and enhances neutrophil production. Exogenous G-CSF administration is indicated for chemotherapy-induced neutropenia management. However, there is a paucity of basic research examining the effects of the concomitant use of G-CSF and chemotherapy on myeloid cells in vivo. Whether concomitant G-CSF and chemotherapy adversely affect myeloid cell proliferation have not been determined. Herein, we examined the effects of the concomitant use of pegfilgrastim and 5-fluorouracil on myeloid cells and peripheral blood cells in mouse models. Balb/c mice were treated intraperitoneally with 5-fluorouracil (20 μg/g b.w.) or a vehicle as a control for 5 days, and pegfilgrastim was administered subcutaneously at 1 μg/g b.w. on day 3. As a result, we demonstrated that the concomitant use of pegfilgrastim suppressed the 5-fluorouracil-induced decrease of granulocytic cells in both bone marrow and peripheral blood in mice. To assess the clinical efficacy of early administration of pegfilgrastim during docetaxel, cisplatin, and 5-fluorouracil therapy in patients with esophageal cancer, we retrospectively identified 42 consecutive patients treated with this regimen. The incidence of both febrile neutropenia and grade 4 neutropenia was significantly lower in patients who received pegfilgrastim than in those who did not receive it (P = 0.002 and P = 0.002, respectively). These results suggest that the concomitant use of pegfilgrastim and chemotherapy, consisting of continuous infusions of 5-fluorouracil, improved chemotherapy-induced neutropenia without detrimental effects on proliferating myeloid granulocytic cells.