Figure 3. TH-302 has hypoxia-selective cytotoxicity against leukemia cell lines and primary AML samples.

A. KBM-5, KG-1, OCI-AML3, MOLM-13, REH, and Nalm-6 cells were exposed to the indicated doses of TH-302 for 6 h under normoxic (21% O_2, white bars) or hypoxic (1% O_2, black bars) conditions and then were washed and incubated for 48 h under normoxic conditions. Effects on apoptosis induction were determined by FACS. B. Three primary leukemia samples (samples #1 and 2 are from ALL patients, sample #3 is from an AML patient) were treated as indicated in A and then were allowed to recover for 24 h under normoxic conditions before cell death was assessed by FACS. C. For patient #3, effect of TH-302 was also determined on the leukemia stem cell–enriched compartment (CD34+/CD123+ cells). D. In vitro cytotoxic activity of TH-302 against normal bone marrow cells. MNC from normal BM samples were exposed to TH-302 as indicated for the primary leukemic samples. Effects on apoptosis induction on the whole population (N=4) or the CD34+ (N=1) cells were determined by FACS (mean of 3 repeats; error bars=SEM).