Abstract
Restoring the tumor suppressive activity of the Hippo signaling pathway lost through dysregulation of the NUAK1/2 and MARK2/3 kinase axis and downstream transcriptional effectors YAP/TAZ has emerged as a new modality for the treatment of several human cancers. Small molecule inhibition of NUAK1/2 and MARK2/3 constitutes a rational approach to block YAP/TAZ nuclear translocation and prevent a pro-oncogenic gene expression program. Modest structural changes to lead compound OICR14489, discovered through computational studies using a NUAK2 homology model, afforded the potent and selective dual NUAK1/2 and MARK2/3 inhibitor OICR16422. Further optimization led to inhibitor OICR19451, which produced an increase in YAP phosphorylation and enhanced cytoplasmic YAP/TAZ localization. In vitro growth inhibition of several cancer cell lines, coupled with the robust in vivo pharmacokinetic properties of OICR19451 marked it as an advanced tool compound suitable for in vivo evaluation. Accordingly, in an orthotopic model of highly metastatic breast cancer, MDA-MB-231 tumor-bearing mice treated with OICR19451 showed reduced metastases, tumor encapsulation and an overall increase in survival indicative of favorable Hippo pathway modulation.