Older Age But Not Donor Health Impairs Allogeneic Granulocyte Colony-Stimulating Factor (G-CSF) Peripheral Blood Stem Cell Mobilization

We evaluated stem cell mobilization in 195 consecutive sibling donors who underwent a uniform mobilization regimen of granulocyte colony-stimulating factor (G-CSF) at 10 μg/kg/day divided into twice daily dosing. On day 5, peripheral blood (PB) CD34 cells/μL were measured immediately prior to peripheral blood stem cell (PBSC) apheresis. Failed mobilization was defined as <20 CD34 cells/μL on day 5. The median age was 52 years and 73 (37%) were 55 years or greater. Comorbid conditions by the Charlson Comorbidity Index (CCI) occurred in 13%, but only 3% had Karnofsky performance status (PS) <100%. Eight (4%) failed mobilization, defined as <20 CD34 cells/μL on day 5. Older age was associated with fewer CD34 cells/μL (P = .002). In addition, 6/73 (8.2%) older donors failed mobilization compared to 2/122 (1.6%) younger donors (P = .054). Comorbidity, sex, race, and donor weight did not influence mobilization. Although low PS was very uncommon, it was associated with reduced mobilization (P = .021), but not mobilization failure. A small fraction of older donors mobilize poorly, and this is not explained by standard measures of comorbidity or PS.