Successful PBSC mobilization with high-dose G-CSF for patients failing a first round of mobilization

PBSC are the preferred source of stem cells for autologous transplantation. However, regardless of the mobilization procedure used, 10%-20% of patient s fail to collect an adequate number to ensure prompt engraftment. There is as yet no standard mobilization procedure for patients who fail a first mo bilization attempt. Here, we describe a highly efficient strategy to obtain an adequate number of stem cells for patients who failed a first mobilizat ion attempt. Seventy-four patients with various hematologic malignancies un derwent initial mobilization with various regimens including hematopoietic growth factors with or without chemotherapy. In 72% of patients, greater th an or equal to 2 x 10(6) CD34(+) stem cells/kg were collected in the initia l mobilization attempt, and patients engrafted in a median of 10 days for n eutrophils and 12 days for platelets. Eighteen patients failed to mobilize adequate numbers of stem cells, defined as the inability to collect 0.2 x 1 0(6) CD34(+) stem cells/kg/day in the first 2-3 days. These patients had th eir apheresis halted. Patients were immediately given G-CSF (32 mu g/kg/day ) for 4 days as a second attempt at mobilization. Eighty-eight percent of t hese patients achieved the target of greater than or equal to 2 x 10(6) CD3 4(+) cells/kg, with a median duration of apheresis of 5 days (including the first and second mobilizations). The mean CD34(+) cells/kg/day increased a fter administration of high-dose G-CSF from 0.16 after the first mobilizati on attempt to 0.61 (p = 0.0002) after the second mobilization. All patients engrafted in a median of 11 and 13 days for neutrophils and platelets, res pectively. We conclude that patients whose apheresis yield is <0.4 x 10(6) CD34(+) cells/kg after the first two apheresis collections can be successfu lly mobilized if high-dose G-CSF is administered immediately and continued until achieving greater than or equal to 2 x 10(6) CD34(+) stem cells/kg.