Blood-derived stem cell collection in acute nonlymphoblastic leukemia: predictive factors for a good yield

Blood-derived stem cell (BDSC) autografting represents an interesting theoretical approach to the treatment of acute nonlymphoblastic leukemia (ANLL). The feasibility and safety of this procedure have now been established by several observations of rapid hematopoietic recovery following high-dose chemotherapy and autologous reinfusion of BDSCs harvested during remission. Using clonogenic assays for granulocyte-macrophage colony-forming units (CFU-GM) and granulocyte erythrocyte monocyte colony-forming units (CFU-GEM), we tested peripheral blood samples from 20 consecutive patients recovering from induction chemotherapy for ANLL. Results were correlated with other clinical and hematological factors in order to define optimal criteria for successful BDSC harvesting. Two different patterns of increment were observed in the number of peripheral blood progenitor cells during early recovery from chemotherapy in our patients, suggesting that a total period of 10-12 days should be covered for ideal BDSC harvesting by cytapheresis. Associated clinical factors that appear predictive for a better yield are: 1) chemotherapy with daunorubicin, cytosine arabinoside, and thioguanine (DAT), 2) synchronous recovery of monocytes and platelets, and 3) a good overall performance status of the patient. Complete remission status and absence of ongoing infection should also be considered when selecting patients for BDSC harvesting. No correlation was found between the number of circulating CFUs, as indicated by the clonogenic assays, and that of either My-10- or HLA-Dr-positive cells identified by immunofluorescence on the same blood samples. In this study, less than 50% of patients with newly diagnosed ANLL would have been considered good candidates for a BDSC harvesting program.