The more, the less: age and chemotherapy load are predictive of poor stem cell mobilization in patients with hematologic malignancies.

Background: Intensive treatment such as autologous peripheral blood stem cell (PBSC) transplantation is an important therapeutic strategy in many hematologic malignancies. A number of factors have been reported to impact PBSC mobilization, but the predictive factors varied from one study to another. This retrospective study assessed our current mobilization and collection protocols, and explored the factors predictive of PBSC mobilization in patients with hematologic malignancies.

Methods: Data of 64 consecutive patients with hematologic malignancies (multiple myeloma, n = 22; acute leukemia, n = 27; lymphoma, n = 15) who underwent PBSC mobilization for over 1 year were analyzed. Four patients with response to treatment of near complete remission or better were administered granulocyte colony-stimulating factor (G-CSF) to mobilize PBSCs. Sixty patients received G-CSF followed by chemotherapy mobilizing regimens. Poor mobilization (PM) was defined as when ≤ 2.0'10(6) CD34(+) cells/kg body weight were collected within three leukapheresis procedures.

Results: The incidence of PM at the first mobilization attempt was 19% (12/64). The PM group was older than the non-PM group (median age, 51 vs. 40 years; P = 0.013). In univariate analysis, there were no significant differences in gender, diagnosis, and body weight between the PM and non-PM groups. A combination of chemotherapy and G-CSF was more effective than G-CSF alone as a mobilizing regimen (P = 0.019). Grade III or IV hematopoietic toxicity of chemotherapy had no significant effect on the mobilization efficacy. Supportive care and the incidence of febrile neutropenia were not significantly different between the two groups. In multivariate analysis, age (odds ratio (OR), 9.536; P = 0.002) and number of previous chemotherapy courses (OR 3.132; P = 0.024) were two independent negative predictive factors for CD34(+) cell yield. PM patients could be managed well by remobilization.

Conclusion: Older age and a heavy load of previous chemotherapy are the negative risk factors for PBSC mobilization.