CAL-101 enhances the activity of several different cytotoxic agents against CLL cells cocultured with MSCs. (A) CLL cells were cocultured with MSCs in medium alone (control) or in medium containing the indicated concentrations of CAL-101, dexamethasone, bendamustine, or fludarabine, or the drugs combined. Displayed are representative contour plots that depict CLL cell viability after 48 hours and after staining with DiOC6 and PI (horizontal and vertical axes, respectively). The viable cell population is characterized by bright DiOC6 staining and PI exclusion, and is gated in the lower right corner of each contour plot. The percentage of viable cells is displayed above each of these gates. (B) The bar diagram represents the mean relative viabilities of CLL cells cocultured with MSCs and the indicated concentrations of CAL-101, dexamethasone, bendamustine, fludarabine, or the drugs combined. Viabilities of drug-treated samples were normalized to the viabilities of control samples at the respective timepoints (100%). Displayed are the means (± SEM) from 9 different patient samples, assessed after 24, 48, and 72 hours. CLL cell survival in the presence of MSC was significantly reduced by combination therapy, with P < .05, as indicated by the asterisks describing the comparison of results from each drug-treated culture to the results from the control culture. Similar data were generated with lower CAL-101 concentration (1μM, 0.5μM, and 0.1μM; see supplemental Figure 4).
