Serum Ferritin Is an Independent Predictive Marker for Stem Cell Mobilization Efficacy in Patients with Hematologic Malignancy.

Autologous stem cell transplantation has been performed to support high-dose chemotherapy in hematologic malignancy. A good mobilization is mainly achieved with several mobilization chemotherapies followed by granulocyte colony stimulating factor (G-CSF). Although the complex mechanism of mobilization of hematopoietic stem cell (HSC) is not fully understood, it may be the results of interactions between hematopoietic stem cell and microenvironment of bone marrow. So, severe accumulation of iron in bone marrow due to frequent transfusions may have some negative effect on not only HSC engraftment but also HSC mobilization. We evaluated 30 patients, 6 (20%) with multiple myeloma, 16 (53%) with malignant lymphoma and 8 (27%) with acute leukemia in order to assess the impact of serum ferritin and CD34⁺ HSC mobilization. All patients treated with high dose chemotherapy and G-SCF (5-10ug/kg) before HSC collecting procedure. Serum ferritin, iron, C-reactive protein levels were measured at the first peripheral blood HSC collection. By evaluating the efficacy of CD34⁺ HSC harvest, 20/30 patients (66%) were considered good mobilizer patients, defined as patients with a CD34⁺ cells collection of >1*10⁶ CD34⁺cells/kg/day, and a subset (5/30, 16.7%) as very poor mobilizer (<0.5*10⁶ CD34⁺cells/kg/day), 5 patients between 0.5 and 1*10⁶ CD34⁺cells/kg/day as poor mobilizer. There was no significant difference between 3 groups in age, diagnosis, disease status and previous treatment but notable statistical difference was found in serum ferritin level (median 1322 ng/mL in very poor group, 1068 ng/mL in poor group, 625 ng/mL in good group, P=0.027). The number of CD34⁺ cells/uL in the peripheral blood on the first day of apheresis was a surrogate marker of the efficacy of stem cell harvest (P<0.005) and it showed a strong correlation with serum ferritin (P=0.003). Especially serum ferritin over 1,000 ng/mL was significant correlated with poor mobilization efficacy (P=0.004). Age, diagnosis, disease status and previous chemotherapy had no correlation with mobilization efficacy in our study. In conclusion, severe accumulation of iron, measured by serum ferritin after repeated transfusion was adverse effect on HSC mobilization and serum ferritin might be independent predictive marker for mobilization efficacy.