G-CSF serum pharmacokinetics during peripheral blood progenitor cell mobilization: neutrophil count-adjusted dosage might potentially improve mobilization and be more cost-effective.

The optimal dosing schedule of G-CSF for peripheral blood progenitor cell (PBPC) mobilization is still under investigation although many centers use 10 microg/kg/day in a single subcutaneous dose. However, G-CSF clearance increases with increasing absolute neutrophil count (ANC). Hence a G-CSF dosage adjusted to ANC might be a reasonable approach. We measured G-CSF trough serum levels by sandwich ELISA assay at different ANCs in eight patients undergoing treatment with filgrastim at 10 microg/kg/day in a single subcutaneous dose. A total of 26 samples were analyzed, and a strong correlation between increasing ANC and decreasing G-CSF levels was found by linear regression analysis (P < 0.0003, r2 = 0.4199). For ANC values above 5000/microl the trough serum levels, ie 24 h after administration, were consistently below the level that provides maximal clonogenic precursor stimulation in vitro (10 ng/ml). Serial serum G-CSF measurements performed in three patients at 0, 3, 6, 9 and 24 h after G-CSF administration, showed a reduction of the area under the curve (AUC) with increasing ANC. For an ANC of 20000/microl or greater, the G-CSF serum level fell under the maximal in vitro stimulation threshold of 10 ng/ml within 12 h. This preliminary pharmacokinetic data seems to suggest that an ANC-adjusted G-CSF dosing schedule might improve the design of PBPC mobilization regimens.

Pediatric peripheral blood progenitor cell collection: haemonetics MCS 3P versus COBE Spectra versus Fresenius AS104.

BACKGROUND: An increasing number of apheresis machines are becoming available for peripheral blood progenitor cell (PBPC) collection in children. STUDY DESIGN AND METHODS: At the Children's Hospital of Florence (Italy), three apheresis machines were evaluated: MCS 3P (Haemonetics) (10 procedures in 4 patients, aged 10-12 years, weight 23.5-64 kg), Spectra, (COBE) (8 procedures in 3 patients, aged 4-17 years, weight 19-59 kg), and AS104 (Fresenius) (24 procedures in 9 patients, aged 2-16 years, weight 13.6-60 kg). For PBPC quantitative analysis, CD34 cytofluorimetry was employed. Relevant variables analyzed included efficiency of CD34+ cell extraction and enrichment, mononuclear cell purity and red cell contamination of the apheresis components, and platelet count decreases after leukapheresis. RESULTS: No significant differences in CD34+ cell-extraction abilities were found. However, the AS104 provided consistently purer leukapheresis components in terms of mononuclear cell and CD34+ cell enrichment (441 +/- 59%, vs. 240 +/- 35% and 290 +/- 42% for MCS 3P and Spectra, respectively). Postapheresis platelet counts dropped the least with the AS104. The smallest patient who underwent apheresis with MCS 3P (the only machine working on discontinuous flow and hence with greater volume shifts) weighed 23.5 kg and tolerated the procedure well, with no signs of hemodynamic instability. No significant complications were observed. CONCLUSION: All machines seem to have comparable PBPC extraction efficiency, but the AS104 seems to give the component with the greatest PBPC enrichment. This feature might be relevant for further ex vivo cell processing (CD34+ cell selection, expansion, and so on).