Ex vivo effects of VLS-101 on RS cells. (A-B) Cell-cycle (A) and cell-viability (B) analyses, obtained by flow cytometry, after ex vivo incubation of RS cells from the 3 ROR1-expressing RS-PDX models (IP867/17, RS1316, and RS1050) with VLS-101 at the indicated doses for 72 hours and 48 hours, respectively (data from at least 3 independent experiments). Data are reported as a percentage of cells in the different cell-cycle phases (mean with standard error of the mean) (A) or percentage of apoptotic cells (B) and statistical analyses performed using the paired Student t test. Box plots of apoptotic data show the distribution of values: median, interquartile range, minimum and maximum values. (C) Western blot confirmation of the activation of the apoptotic cascade, by checking cleavage of poly (ADP-ribose) polymerase (PARP) and caspase-3, in RS cells treated ex vivo with VLS-101 at the indicated doses at 24 and 48 hours of exposure. Actin was used as a loading control. Numbers below bands indicate the mean fold change of VLS-101–treated cells over vehicle-treated ones (3 independent experiments). The fold change was calculated as follows: intensity of cleaved band over intensity of full-length band, both normalized over actin band. *P < .05; **P < .01; ***P < .001; ****P < .0001. CL, cleaved; FL, full-length; NT, vehicle-treated samples.