Coadministration of MLN4924 and belinostat suppresses tumor growth in a murine xenograft flank model. Nude mice were s.c. inoculated in the right rear flank with 5 × 106 luciferase-expressing U937 cells. Treatment was initiated after luciferase signal was detected. MLN4924 was reconstituted weekly with 20% HPbCD (HY-100; ONBIO) and administrated at a dose of 30 mg/kg via s.c. injection twice daily for 3 continuous days followed by 2 days off every 5 days. Stock solution of 50 mg/mL belinostat in 100 mg/mL l-arginine (Sigma A8094; belinostat: l-arginine = 1:2) was formulated and stored at −20°C. Belinostat stock solution was freshly diluted in isotonic saline and administrated at a dose of 40 mg/kg via i.p. injection daily 5 days a week. Control animals were administered equal volumes of vehicle. (A) Tumor growth was monitored every other day after i.p. injection with 150 mg/kg luciferin using the IVIS 200 imaging system. Representative images of 3 mice are shown. Red crossed lines indicate that mice were euthanized when tumor size reached 1700 mm3 or other humane end points (eg, abscessed or necrotic tumors) were reached. (B) Western blot analysis was performed to monitor the indicated candidate PD markers, identified from in vitro experiments, in tumors excised from representative mice.
