pyrimidinones and mafosfamide

Human acute myelogenous or lymphoblastic leukemia cells of the K-562 and CCRF-SB lines were mixed with an excess of normal human bone marrow cells to simulate a leukemia remission marrow. The cell mixtures were then incubated in vitro with mafosfamide (AZ) followed by the photoreactive dye merocyanine-540 (MC). Treated cells (1 x 10(4] were seeded in microwell plates, and increasing numbers of the line used to contaminate the normal marrow were added. Treatment with AZ alone produced total elimination (i.e., 6 logs) of CCRF-SB cells, while addition of merocyanine-540 increased the cloning efficiency from 22% to 24.4%. After treatment of the K-562-contaminated cell mixtures with AZ, nearly 1.6 logs of K-562 acute myelogenous blasts were still present, whereas AZ purging followed by MC-mediated photosensitization resulted in 100% elimination of clonogenic cells. Moreover, the combined treatment caused an increase of the cloning efficiency from 37.3% to 62%, clearly indicating that cleansing by the two agents combined was more effective than treatment with one agent alone.

Topics: Antineoplastic Agents; Bone Marrow; Cell Line; Colony-Forming Units Assay; Cyclophosphamide; Dye Dilution Technique; Humans; Leukemia; Light; Pyrimidinones; Radiation-Sensitizing Agents; Tumor Stem Cell Assay

To stimulate a leukemia remission marrow, cell suspensions of normal human bone marrow were mixed with human acute lymphoblastic or myelogenous leukemic cells of the CCRF-SF, Nalm-6, and K-562 lines. The cell mixtures were incubated in vitro with mafosfamide (AZ) or with the photoreactive dye merocyanine 540 (MC-540). A quantity of 10(4) cells of the treated suspensions was dispensed into microculture plates, and graded cell numbers of the line used to contaminate the normal marrow were added. Limiting-dilution analysis was used to estimate the frequency of leukemia cells persisting after treatment with the decontaminating agents. Treatment with AZ or MC-540 produced a total elimination (ie, 6 logs or 5.3 logs respectively) of B cell acute leukemia cells (CCRF-SB), whereas nearly 1.7 logs and 2 logs of K-562 acute myelogenous blasts were still present in the cell mixtures after treatment with MC-540 and AZ, respectively. Treatment of the Nalm-6-contaminated cell mixtures with AZ resulted in 100% elimination of clonogenic cells, whereas nearly 80% decontamination was obtained with MC-540. Our results suggest that treatment with AZ could be an effective method of eliminating clonogenic tumor cells from human bone marrow. MC-540, shown by previous studies to spare sufficient pluripotential stem cells to ensure hemopoietic reconstitution in the murine model and in clinical application, has comparable effects and merits trials for possible clinical use in autologous bone marrow transplantation.

Topics: Bone Marrow; Bone Marrow Cells; Cell Line; Cyclophosphamide; Humans; Leukemia, Lymphoid; Leukemia, Myeloid, Acute; Pyrimidinones; Radiation-Sensitizing Agents