Optimising parameters for peripheral blood leukapheresis after r-metHuG-CSF (filgrastim) and r-metHuSCF (ancestim) in patients with multiple myeloma: a temporal analysis of CD34+ absolute counts and subsets

Patients (n = 69) with multiple myeloma undergoing peripheral blood stem cell collection (PBSC) were treated with cyclophosphamide and a combination of recombinant methionyl human granulocyte colony-stimulating factor (r-metHuG-CSF, filgrastim) and recombinant methionyl human stem cell factor (r-metHuSCF, ancestim). The objectives of this study were to determine: (1) The proportion of patients reaching a target yield of ⩾5 × 106 CD34+ cells/kg in one or two successive large-volume (20 liter) leukapheresis procedures; (2) the optimal collection time for leukapheresis; (3) mobilization kinetics of CD34+ subsets in response to G-CSF/SCF. All patients were mobilized with cyclophosphamide (2.5 g/m2) on day 0 followed by filgrastim (10 μg/kg) plus ancestim (20 μg/kg) commencing day 1 and continuing to day 11 or 12. Of the 65 evaluable patients, 57 were considered not heavily pretreated and 96.5% obtained a target of ⩾5 × 106/kg in one collection. The median CD34+ cells/kg was 39.5 × 106 (range: 5.2–221.2 × 106). Subset analysis demonstrated the number of CD38−, CD33−, and CD133+ peaked at day 11; and CD34+, CD90+ cells peaked at day 10. The optimum day for leukapheresis was determined to be day 11. The median absolute peripheral blood CD34+ cell numbers on day 11 was 665 × 106/l (range: 76–1481 × 106/l). Eight of the 10 heavily pretreated patients were evaluable: three achieved the target dose in one leukapheresis (37.5%) and three (37.5%) achieved the target dose with two leukaphereses. Use of this mobilization strategy allowed the collection of high numbers of CD34+ cells and early progenitors and the ability to predictably schedule leukapheresis.