Cancer Therapy: Preclinical Dasatinib Plus Nutlin-3 Shows Synergistic Antileukemic Activity in Both p53 and p53 B Chronic Lymphocytic Leukemias by Inhibiting the Akt Pathway

Purpose: To analyze the effect of the combination of Dasatinib, a multikinase inhibitor, plus Nutlin-3, a nongenotoxic activator of the p53 pathway, in primary B chronic lymphocytic leukemia (B-CLL) patient samples and B leukemic cell line models. Experimental Design: The induction of cytotoxicity was evaluated in both primary B-CLL cell samples (n 1⁄4 20) and in p53 (EHEB, JVM-2) and p53 (MEC-2, BJAB) B leukemic cell lines. The role of Akt in modulating leukemic cell survival/apoptosis in response to Dasatinib or Dasatinib þ Nutlin-3 was documented by functional experiments carried out using specific pharmacological inhibitors and by overexpression of membrane-targeted constitutively active form of Akt. Results: The combination of Dasatinib þ Nutlin-3 exhibited a synergistic cytotoxicity in the majority (19 out of 20) of B-CLL samples, including patients carrying 17p(n 1⁄4 4), and in both p53 and p53 B leukemic cell lines. At the molecular level, Dasatinib significantly counteracted the Nutlin-3-mediated induction of the p53 transcriptional targets MDM2 and p21 observed in p53 leukemic cells. Conversely, Nutlin-3 did not interfere with the ability of Dasatinib to decrease the phosphorylation levels of ERK1/2, p38/MAPK, and Akt in both p53 and p53 B leukemic cell lines. A critical role of Akt downregulation in mediating the antileukemic activity of Dasatinib and Dasatinib þ Nutlin-3 was demonstrated in experiments carried out by specifically modulating the Akt pathway. Conclusions: These findings suggest that Dasatinib þ Nutlin-3 might represent an innovative therapeutic combination for both p53 and p53 B-CLL. Clin Cancer Res; 17(4); 762–70. 2010