PEG-ZnPP and SMA-ZnPP inhibit growth of primary CML cells. Isolated leukemic cells from patients with newly diagnosed CP CML (A,B) or advanced phase CML (C: AP; D: BP) were stimulated with GM-CSF (100 U/mL) for 7 days and then incubated with control medium (0), various concentrations of PEG-ZnPP (left panels), or various concentrations of SMA ZnPP (right panels) at 37°C for 48 hours. Thereafter, ³H-thymidine incorporation was determined. Results show the percentage of ³H-thymidine uptake compared with control (100%) and represent the mean (± SD) of triplicates in each patient. (E) Sorted pure CD34-positive progenitor cells from a patient with newly diagnosed CP CML were incubated with control medium (0) or various concentrations of SMA-ZnPP at 37°C for 48 hours. Thereafter, ³H-thymidine uptake was determined. Results are expressed as percent ³H-thymidine uptake compared with control (100%) and represent the mean (± SD) of triplicates. (F) CD34-positive progenitor cells from 3 CML patients were incubated with control medium (Co) or SMA-ZnPP (20 μM) for 48 hours. Thereafter, ³H-thymidine incorporation was determined. Results represent the mean (± SD) of 3 independent experiments (3 patients). *P < .05 compared with control. (G) Isolated CD34⁺ CML progenitor cells were cultured in control medium (left panel) or in the presence of SMA-ZnPP (10 μM) (right panel) for 4 days. Thereafter, the percentage of apoptotic cells was determined by annexin V staining and FACS analysis.