WP1130 reduces the growth of CML tumors and Bcr/Abl-expressing cells in nude mice. K562 cells were inoculated subcutaneously into nude mice as described. Initial tumor volumes were measured 10 days later, and the mice were randomly assigned to 3 treatment groups (5 animals/group). Animals were treated with WP1130 (30 mg/kg every other day for 9 days, 5 injections) or imatinib mesylate (50 mg/kg every day for 9 days, 9 injections). Tumors were measured with electronic calipers, and volumes were calculated in cubic millimeters by determining the length × breadth × height of each tumor. Results are expressed as mean ± standard error of the mean of the measurements from all 5 animals per group during the treatment. Animals were weighed when the tumors were measured, and no difference in body weight was noted between treated or control animals (data not shown). (B) BaF/3/WT- or BaF/3/T315I Bcr/Abl-expressing cells were injected (intravenously) into nude mice as described in “Materials and methods.” One day later, animals were randomly separated into 3 groups. One group received vehicle alone (control), the second group received imatinib mesylate daily, and the third group was treated with WP1130 every other day. Fifteen days after tumor cell inoculation, animals were killed, and their spleens were removed, weighed, and photographed. Spleens from non–tumor-bearing animals (normal spleen) were also photographed for comparison. (C) The average ± SEM spleen weight from each treatment group is shown. P < .01 from Student t test.