Table 1.

 Inhibitory effects of JTE‐607, Cytarabine, and Daunorubicin on proliferation of AML and MDS cell lines, and human bone marrow CFU‐GM colony formation

	JTE‐607		Cytarabine		Daunorubicin
	IC50 (μmol/L)	Ratio	IC50 (μmol/L)	Ratio	IC50 (μmol/L)	Ratio
hCFU‐GM	2.2 ± 0.1	—	0.0059 ± 0.0003	—	0.0068 ± 0.0006	—
U‐937	0.043 ± 0.002	51	0.0041 ± 0.0003	1.4	0.010 ± 0.002	0.68
HL‐60	0.058 ± 0.01	38	0.014 ± 0.001	0.42	0.0041 ± 0.00008	1.7
THP‐1	0.18 ± 0.02	12	0.19 ± 0.02	0.031	0.017 ± 0.0005	0.40
KG‐1	0.80 ± 0.3	2.8	0.011 ± 0.002	0.54	0.019 ± 0.0004	0.36
Kasumi‐1	0.11 ± 0.02	20	0.0036 ± 0.0002	1.6	0.011 ± 0.002	0.62
Kasumi‐3	4.0 ± 0.6	0.6	0.0045 ± 0.0004	1.3	0.055 ± 0.003	0.12
SKM‐1	0.26 ± 0.01	8.5	0.024 ± 0.005	0.25	0.015 ± 0.001	0.45

Human bone marrow mononuclear cells were incubated for 14 days in semi‐solid culture medium with or without various concentrations of test compound, and formed colony‐forming unit‐granulocyte/macrophage (CFU‐GM) colonies were counted. Acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) cells were cultured for 3 days in the presence of the compound, and were pulsed with [³H]‐thymidine during the last 6 h of the culture. The amount of [³H]‐thymidine incorporated was measured as an indicator of cell proliferation. Each IC₅₀ value represents the mean ± SEM of three independent experiments. Ratio = IC₅₀ from human CFU‐GM assay/IC₅₀ from cell proliferation assay.