Mobilization and harvesting of peripheral blood stem cells: randomized evaluations of different doses of filgrastim

The effects of different doses of filgrastim on yields of CD34(+) peripheral blood stem cells were evaluated in patients with breast cancer, 55 were randomized to receive filgrastim 10, 20, 30 or 40 mu g/kg/d with more CD34(+) cells/kg/apheresis harvested after the three highest dose levels. 35 additional patients were randomized to receive 10 or 30 mu g/kg. The median number of CD34(+) cells collected after 10 mu g/kg (n=31) was 0.7 x 10(6)/kg/apheresis (range 0.1-4.4) as compared to 1.2 (range 0.1-6.8) after 30 mu g/kg (n = 32) (P = 0.04). Among patients randomized to 10 v 30 mu g/kg, more (50%) achieved greater than or equal to 5.0 x 10(6) CD34(+) cells/kg and less aphereses were required to achieve greater than or equal to 2.5 x 10(6) CD34(+) cells/kg after the higher dose (P = 0.04). In multivariate analyses, patients receiving 10 mu g/kg (n = 31) had lower yields of CD34(+) cells (P = 0.026) and had a 3.3-fold increase in the probability of not achieving greater than or equal to 5.0 x 10(6) CD34(+) cells/kg as compared to patients receiving 20-40 mu g/kg (n=59). Patients who had received radiation had a 2.9-fold probability of not achieving greater than or equal to 2.5 x 10(6) CD34(+) cells/kg. These data suggest that, in patients with good marrow reserves, doses of filgrastim > 10 mu g/kg/d mobilized more CD34(+) cells and may be useful when high numbers of CD34(+) cells are desired.