Recombinant human glycosylated granulocyte colony-stimulating factor (rhG-CSF)-combined regimen for allogeneic bone marrow transplantation in refractory acute myeloid leukemia

Recombinant human glycosylated G-CSF (rhG-CSF) may stimulate proliferation of myeloid leukemia cells and thereby increase their susceptibility to anti cancer agents. By in vitro colony assay, the rhG-CSF-responsive NFS-60 leukemic cell clones are more effectively killed by Ara C in the presence of rhG-CSF than in the absence of rhG-CSF, while the killing of the rhG-CSF-unresponsive HL-60 cell clones is unaffected by rhG-CSF. Leukemia cell colony forming units (L-CFU) derived from most AML patients demonstrate similar results to those of the NFS-60 cell clone when treated in vitro. Encouraged by these in vitro results, we used rhG-CSF as a component of a conditioning regimen for 15 relapsed AML patients who were receiving allogeneic BMT. The patients were conditioned with total body irradiation (TBI) and high-dose Ara C. rhG-CSF was infused continuously at a dose of 5 μg/kg/day from 24 h before the beginning of TBI to the end of Ara C therapy. Proliferation of the leukemia cells in vivo in response to rhG-CSF was confirmed in 7 of 14 patients tested and the combined use of rhG-CSF had no additional adverse effects. After BMT, four patients died of non-leukemic causes and three patients had leukemic relapse: the other eight patients have remained disease-free for 200-1600 (median 417) days. The actuarial probabilities of relapse and disease free survival (DFS) at 4.4 years after BMT were 43.2% and 41.7%, respectively. These results suggest that the rhG-CSF-combined preparative regimen for BMT has potential benefit in prolonging the duration of remission after BMT and improving DFS rate in AML.