Factors influencing stem cell mobilization in patients with hematologic malignancies and solid tumors

Mobilized peripheral blood stem cells (PBSC) have become the main source for autologous and allogeneic hemopoietic stem cells transplantation (HSCT) following myeloablative therapy in patients with hematological malignancies or solid tumors. Classical strategies for PBSC mobilization include administration of granulocyte colony-stimulating factor (G-CSF) alone or in combination with other agents or myelosuppressive chemotherapy. PBSC mobilization and collection have been optimized in numerous clinical trials, but a proportion of patients fail to mobilize. The aim of the study was to establish the influence of diagnosis, sex, age, number of previous courses of chemotherapy, mobilization regimen, and bone marrow (BM) involvement on the outcome of peripheral blood stem cell mobilization. Patients and methods. 121 patients with hematological malignancies and solid tumors were included in the study (Hodgkin’s lymphoma (HD) (n=24), non-Hodgkin lymphomas (NHL) (n=29), multiple myeloma (MM) (n=32), acute leukemias (AL) (n=15), and solid tumors (ST) (n=21)). 100 patients (82%) were mobilized with G-CSF, and a combination of chemotherapy and G-CSF was used in 21 patients (18%). 57 patients (49%) received more than six courses of chemotherapy and 74 (51%) less than six respectively. The criterion for adequate mobilization was a score of at least 2.0 x 106 CD34+ cells/kg of body weight. Results. In our trial there was no correlation between PBSC yield and the patient’s diagnosis, age, or gender. BM involvement does not seem to be an independent factor, with significant adverse influence on PBSC mobilization (p=0.78). Stem cell yield was significantly higher in those patients who received fewer than six courses of chemotherapy (10.0 ± 2.2 х 106 CD34+/kg against 5.5 ± 1.7 х 106 CD34+/kg (p=0.006)). A better outcome was seen in patients mobilized with chemotherapy plus G-CSF than with G-CSF alone (8.12 ± 1.12 х 106 CD34+/kg against 6.9 ± 0.9 х 106 CD34+/kg (p= 0.008)).Conclusions. Diagnosis, age, sex, and bone marrow involvement does not influence the outcome of stem cell mobilization. Better stem cell yield was seen in patients who received fewer than six courses of chemotherapy, and in patients mobilized with cytokines combined with chemotherapy than cytokines alone.