High- Versus Standard-Dose Filgrastim (rhG-CSF) for Mobilization of Peripheral-Blood Progenitor Cells From Allogeneic Donors and CD34+ Immunoselection

Abstract

PURPOSE: The efficacy of a high- versus a standard-dose filgrastim (recombinant human granulocyte colony-stimulating factor, or rhG-CSF) regimen to mobilize peripheral-blood progenitor cells (PBPCs) for allogeneic transplantation was investigated in 75 healthy donors. PATIENTS AND METHODS: From December 1994 to December 1997, 75 consecutive donors (median age, 38 years; range, 17 to 67 years) were assigned to two different schedules of rhG-CSF for PBPC mobilization. Fifty donors received 24 μg rhG-CSF/kg body weight (BW) divided into two daily subcutaneous injections (two doses of 12 μg, group A), whereas 25 were treated with 10 μg rhG-CSF once daily (group B). Apheresis was started on day 4 in group A and on day 5 in group B. Target CD34+ cell numbers in apheresis products were ≥ 4 × 106/kg recipient BW. RESULTS: Cytokine priming and collection of PBPCs were equally well tolerated in both groups. Significantly higher CD34+ cell numbers in group A with 3.7 × 106/kg recipient BW/apheresis (0.47 × 106/L apheresis) compared with 2 × 106/kg recipient BW/apheresis (0.25 × 106/L apharesis) in group B were obtained (P < .05). Using standard aphereses (median, 9 L), two doses of 12 μg rhG-CSF/kg allowed collection of ≥ 4 × 106/kg CD34+ cells with two aphereses (range, one to three) in group A versus three aphereses (range, one to six) in group B (P < .015). Donor age, sex, and BW influenced the collection of CD34+ cell numbers: in particular, significantly higher apheresis results were obtained in donors younger than 40 years compared with donors older than 40 years of age (P < .05). In 65 CD34+ selection procedures using avidin-biotin immunoabsorption columns (Ceprate SC System, CellPro, Bothell, WA), a median CD34+ purity of 53%, CD34+ recovery of 40%, and the collection of 2 × 106/kg CD34+ cells/selection were achieved. In group A with higher CD34+ cells/kg/apheresis, CD34+ purity, recovery, and cell yields were 60%, 45%, and 2.3 × 106/kg/selection, respectively, as compared with 48%, 31%, and 0.7 × 106/kg in group B (P < .05). CONCLUSION: Our results demonstrate that twice daily rhG-CSF (two doses of 12 μg/kg BM) compared with once daily rhG-CSF (10 μg/kg BW), in addition to being well tolerated, significantly improves PBPC mobilization, allows the collection of higher numbers of CD34+ cells with one or two standard aphereses, and facilitates subsequent selection procedures in healthy allogeneic donors.