OSU03012 is cytotoxic toward CLL cells in vitro. PBMCs from 11 patients with CLL were incubated in various concentrations (1 μM, 5 μM, 10 μM, and 50 μM) of OSU03012 for 24 (▪) or 72 hours (▦). MTT reagent was then added, and plates were incubated for an additional 24 hours before analysis. Each bar represents the mean of 11 patients. Error bars indicate standard deviation.