Antileukemic activity of panobinostat alone, cytarabine alone, and panobinostat plus cytarabine in a U937 xenograft model.

<p>NOD-SCID-IL2Rγ^null (NSG) mice were injected with luciferase-labeled U937 cells and treated 3 days later with panobinostat (5 mg/kg once daily for 3 weeks), ara-C (6.25 mg/kg once daily for 4 weeks), or combination (panobinostat 5 mg/kg once daily for 3 weeks plus ara-C 6.25 mg/kg once daily for 4 weeks). Serial bioluminescence images of representative mice receiving panobinostat alone (n = 8), ara-C alone (n = 10), or panobinostat plus ara-C (n = 8) (<b>Panel A</b>). When bioluminescence reached 1.5×10⁷ p/s/cm²/sr, day 17 after injection of U937 cells, mice received panobinostat (5 mg/kg once daily×2). Four hours after the second dose mice were sacrificed and Bone Marrows were harvested. Pellets were lysed and subjected to Western Blot (<b>Panel B</b>). Tumor progression monitored by quantitative biophotonic imaging analysis of control and treatment groups (<b>Panel C</b>). A plot of overall survival probability, estimated with the Kaplan–Meier method (<b>Panel D</b>).