Pan-AKI and TRAIL combination therapy has potent antitumor activity in vivo against drug-resistant human MM xenograft model. (Ai) When tumor size reached 250 mm3, mice were randomly assigned (n = 10/group) to receive vehicle alone, MK-0457 (50 mg/kg), PHA-680632 (50 mg/kg), TRAIL (300 μg/mouse), or the combination MK-0457/TRAIL or PHA-680632/TRAIL. TRAIL was administered once on days 3 and 6. Pan-AKIs were administered once each day for 11 days. Results are tumor volume, mean ± SD mm3, plotted against time (P < .001 MK-0457/TRAIL or PHA-680632/TRAIL vs either treatment alone; Dunnet test). Inset shows tumors resected from control (vehicle) and pan-AKI/TRAIL-treated mice after 11 days of treatment (endpoint). (ii) Kaplan-Meier survival curve was evaluated from the first day of treatment until death or sacrifice using JMP version 7.0 statistical software (SAS Institute, Cary, NC). Survival was significantly prolonged in MK-0457/TRAIL-treated animals vs control (P = .0015 after Bonferroni correction). The black bar on the abscissa represents the 11-day period of treatment. After 6 days of treatment, mice from each treatment group (n = 3/group) were humanely killed, and the tumors were removed for assay. RPMI 8226/R5-derived tumors were analyzed by immunohistochemical staining for (B) phospho-Histone H3 (×10, ×20, and ×40 magnification), (C) hematoxylin and eosin (H&E), and cleaved caspase-3 (×4, ×10, and ×20 magnification). The microphotographs shown are representative of similar observations in 3 different mice receiving the same treatment. (D) Tumor tissues from mice treated for 6 days were harvested and processed, and lysates were analyzed by immunoblotting analysis for PARP, cleaved-PARP, and cleaved caspase-3. Anti-actin immunoblotting was performed as loading control.
