No preferential sensitivity of clonogenic AML cells to ASTA-Z-7557.
ASTA-Z-7557, an in vitro active metabolite of cyclophosphamide, has recently been introduced to purge autologous bone marrow grafts of patients with AML. The rationale of this approach assumes a relatively higher sensitivity of leukemic cells to the drug as compared to that of normal marrow precursors. We have investigated in direct comparison the sensitivity to ASTA-Z-7557 of normal bone marrow progenitors (GM-CFC and BFU-E) and clonogenic leukemic cells (L-CFC). Normal bone marrow cells and purified leukemic blast cells were exposed to varying concentrations of the drug. Dose-response relationships did not indicate a selective cytotoxic susceptibility of L-CFC to ASTA-Z-7557. The recovery of bone marrow precursors following exposure to ASTA-Z-7557 depended on the cell concentration during exposure and was higher for 2 X 10(7) cells/ml than for 1 X 10(6)/ml. To mimic minimal residual leukemia cell mixtures of 95% irradiated normal bone marrow cells with 5% leukemic blast cells were exposed to ASTA-Z-7557. In this mixture killing of L-CFC was largely decreased. These data suggest that in vitro incubation of autologous bone marrow grafts of patients with minimal residual leukemia with ASTA-Z-7557 might not offer a therapeutic advantage.
D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003520:Cyclophosphamide / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D006412:Hematopoietic Stem Cells / Q000187:drug effects*; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy* / Q000473:pathology
C037933:Asta Z 7557; D003520:Cyclophosphamide