CBP Modulates Sensitivity to Dasatinib in Pre-BCR⁺ Acute Lymphoblastic Leukemia

Dasatinib is a multi-tyrosine kinase inhibitor approved for treatment of Ph⁺ acute lymphoblastic leukemia (ALL), but its efficacy is limited by resistance. Recent preclinical studies suggest that dasatinib may be a candidate therapy in additional ALL subtypes including pre-BCR⁺ ALL. Here we utilized shRNA library screening and global transcriptomic analysis to identify several novel genes and pathways that may enhance dasatinib efficacy or mitigate potential resistance in human pre-BCR⁺ ALL. Depletion of the transcriptional coactivator CBP increased dasatinib sensitivity by downregulating transcription of the pre-BCR signaling pathway previously associated with dasatinib sensitivity. Acquired resistance was due, in part, to upregulation of alternative pathways including WNT through a mechanism, suggesting transcriptional plasticity. Small molecules that disrupt CBP interactions with the CREB KID domain or β-catenin showed promising preclinical efficacy in combination with dasatinib. These findings highlight novel modulators of sensitivity to targeted therapies in human pre-BCR⁺ ALL, which can be reversed by small-molecule inhibitors. They also identify promising therapeutic approaches to ameliorate dasatinib sensitivity and prevent resistance in ALL.Significance: These findings reveal mechanisms that modulate sensitivity to dasatinib and suggest therapeutic strategies to improve the outcome of patients with acute lymphoblastic leukemia.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/22/6497/F1.large.jpg Cancer Res; 78(22); 6497-508. ©2018 AACR.