Impact of Mobilization and Remobilization Strategies on Achieving Sufficient Stem Cell Yields for Autologous Transplantation

The purpose of this article was to examine historic institutional autologous stem cell mobilization practices and evaluate factors influencing mobilization failure and kinetics. In this retrospective study we analyzed clinical records of 1834 patients who underwent stem cell mobilization for autologous transplantation from November 1995 to October 2006 at the Washington University in St. Louis. Successful mobilization was defined as collection of ≥2 × 106 CD34+ cells/kg. From 1834 consecutive patients, 1040 met our inclusion criteria (502 non-Hodgkin's lymphoma [NHL], 137 Hodgkin's lymphoma, and 401 multiple myeloma [MM]). A total of 976 patients received granulocyte colony-stimulating factor (G-CSF) and 64 received G-CSF plus chemotherapy (G/C) for the initial mobilization. Although the median CD34+ cell yield was higher in G/C group than in G-CSF alone group, the failure rates were similar: 18.8% and 18.6%, respectively. Overall, 53% of patients collected ≥2 × 106 CD34+ cells/kg during the first apheresis with either mobilization regimen. Regardless of mobilization regimen used, MM patients had the highest total CD34+ cell yield and required less aphereses to collect ≥2 × 106 CD34+ cells/kg. Mobilized, preapheresis, peripheral blood CD34+ count correlated with first day apheresis yield (r = .877, P < .001) and 20 cells/μL was the minimum threshold needed for a successful day 1 collection. For the remobilization analysis we included patients from the whole database. A total of 269 of 1834 patients underwent remobilization using G/C, G-CSF, and/or GM-CSF, and G-CSF plus plerixafor. Only 23% of remobilized patients achieved ≥2 × 106 CD34+ cells/kg and 29.7% failed to pool sufficient number of stem cells from both collections. Patients receiving G-CSF plus plerixafor had lowest failure rates, P = .03. NHL patients remobilized with G-CSF who waited ≥25 days before remobilization had lower CD34+ cell yield than those who waited ≤16 days, P = .023. Current mobilization regimens are associated with a substantial failure rate irrespective of underlying disease. Patients who fail initial mobilization are more likely to fail remobilization. These findings suggest that there is a need for more effective first-line mobilization agents.