The combination of romidepsin and KU60019 is synergistic in a xenograft model of MCL. (A) The in vivo therapeutic efficacy of romidepsin and KU60019 as single agents and combination was evaluated using a SCID Beige xenograft mouse model of MCL. The effectiveness of romidepsin in combination with KU60019 was evaluated in a 3 week cycle administration. Romidepsin was administered weekly at days 1, 8, and 15. KU60019 was given at days 1, 2, 3, 4, and 5 of each week. The data are expressed as average tumor volume (mm3) per group as a function of time. A two-tailed t test confirmed that combination was statistically superior to both the single agents and the control in inhibiting tumor growth (0.001 < P < 0.05). (B) Statistical analysis of survival following the 3 weeks administration cycle. When compared to control, only the romidepsin plus KU60019 combination was statistically significant. P-value, standard error of the mean (SEM), coefficient of determination (R squared), and coefficient of correlation (r) of comparisons.