CR4 cells are highly resistant to treatment with cytotoxic drugs (comparative cytotoxicity of paclitaxel and new-generation taxoids against CR4 cells).

<p>Commonly used Paclitaxel (Taxol) in doses lower than 10 µM is not effective against CR4 cells and often increases their proliferation. In contrast, several new-generation taxoids induce dose-dependent inhibition of proliferation of these potent tumor-initiating cells. (MTT assay after drug treatment for 48 hr). The obtained <i>p</i> values for all the drugs and all the drug concentrations were much smaller that 0.05. The largest <i>p</i> value was obtained for SBT-1214 at 10 nM concentration (<i>p</i> = 0.0131); in particular, at 10 µM concentration of SBT-1214 <i>p</i> = 0.00032.