Assessment of drug response in Vk*MYC MM. (A) IC50 (nM) of the indicated drugs obtained by MTT assay in various HMCLs. Each dot represents a cell line, and bars show median values plotted on a log10 scale. In green or red are labeled drugs with single-agent response rates in MM clinical trials above or below 20%, respectively. (B) SPEP and densitometric profile of Vk*MYC mice treated with known active antimyeloma drugs. The day 0 (filled) and day 14 (pink line) traces have been overlaid. The various serum fractions on the densitometry plot are labeled. Arrows point to M-spikes before (day 0) and after (day 14) treatment. (C) The response of Vk*MYC mice to drugs with known (green, red) or (D) unknown (black) activity. Drug activity is quantified by measuring M-spike levels at day 14 after treatment normalized to day 0. Each dot represents an individual M-spike. Bars show median M-spike levels at day 14 normalized to day 0. A blue line in each dot plot arbitrarily separates active drugs (> 50% M-spike reduction, on the left) from inactive ones (< 50% M-spike reduction, on the right). The P value of active drugs compared with vehicle is shown. PLD indicates pegylated liposomal doxorubicin.
