Experimental study on safety for granulopoiesis in simultaneous therapy with recombinant human granulocyte colony-stimulating factor and chemotherapy.

Since recombinant human granulocyte colony-stimulating factor (rhG-CSF) recruits hematopoietic progenitor cells into the cell cycle, the possibility remains that simultaneous injection of rhG-CSF and chemotherapeutic agents may aggravate the chemotherapy-induced neutropenia by sensitizing normal progenitor cells to the cytotoxic effects of chemotherapeutic agents. Therefore, the use of rhG-CSF is usually restricted from the day after chemotherapy. In the present study, we investigated whether concurrent treatment with rhG-CSF and chemotherapeutic agents aggravated granulopoietic failure, using murine neutropenic models. Neutropenia induced by a single injection of cyclophosphamide, mitomycin C, adriamycin, vincristine, combination of mitomycin C+vincristine, or combination of cyclophosphamide+vincristine+adriamycin (CHOP) was not aggravated by simultaneous injection of rhG-CSF (30 micrograms/kg, SC). In contrast, a single concurrent injection of rhG-CSF and 5-fluorouracil aggravated the neutropenia and the decrease in marrow colony-forming unit-granulocyte/macrophage counts, but simultaneous and following injections of rhG-CSF enhanced the recovery of neutrophils. Moreover, neutropenia induced by successive treatment with cisplatin was prevented by concurrent treatment with rhG-CSF during the period of the chemotherapy. From these results, concurrent treatment with rhG-CSF and chemotherapeutic agents with the exception of 5-fluorouracil may be feasible and well-tolerated in clinical use.