Combinatorial antitumor efficacy of ACY738 and ibrutinib treatment in CLL mice. (A) Overall survival data for adoptive transfer CLL mice treated as indicated until death or euthanasia (n = 8 per group), representative of 2 independent experiments. (B-C) CLL burden was quantified in peripheral blood or spleen after 12 weeks of indicated treatments; data are representative of 3 independent experiments. (D) Spleen weight at conclusion of experiment. (E) Representative spleens from indicated treatment groups are shown. Error bars correspond to standard errors of the mean. *P < .05, **P < .005, ***P < .0005, ****P < .00005.