Mobilization of peripheral blood progenitor cells with a combination of cyclophosphamide, r-metHuSCF and filgrastim in patients with breast cancer previously treated with chemotherapy

The objective of our study was to determine the effect of adding r-metHuSCF to Filgrastim and cyclophosphamide for mobilization of peripheral blood progenitor cells (PBPC), on collection of CD34(+) cells and engraftment after autologous stem cell transplant. Twenty-three patients with previously treated stage II-IV breast cancer received cyclophosphamide (3 g/m(2)), Filgrastim 5 mug/kg daily and r-metHuSCF 20 mug/kg daily. Two PBPC collections were performed on consecutive days starting the day the WBC count was above 7.5 x 10(3)/mul. Collection was performed between days +9 and +12 and the median number of CD34(+) cells collected was 9.9 x 10(6)/kg (1.1-53.1) and 6.6 x 10(6)/kg (1.4-33.8) for the first and second apheresis, respectively. Despite being previously treated patients, the target CD34(+) cell dose required for SCT was obtained in all patients. SCT was associated with rapid neutrophil and platelet engraftment and a highly significant correlation was observed between the number of CD34(+) cells infused and engraftment. Treatment with SCF plus filgrastim was well tolerated, with mild to moderate local skin rash being the most frequently reported adverse event. In conclusion, addition of r-metHuSCF induces mobilization of a large number of CD34(+) cells which results in shortening of time to engraftment and hospitalization.