Abstract B06: Development of selective LATS1/LATS2 inhibitors for the pharmacologic modulation of the Hippo signaling pathway

We performed a large-scale profiling of currently available kinase inhibitors (KI) to identify “off-targets” that could be repurposed/repositioned as the starting point for the rational development of novel and selective kinase inhibitors against underdrugged targets. We profiled 257 KI at a single dose against a panel of 365 wild-type kinases tested individually, for a total of about 100,000 in vitro drug/kinase data points. After unsupervised hierarchical clustering of this dataset based on percent inhibition values, we identified a well-resolved subcluster driven by 5 KI with limited polypharmacology and a clean kinase-inhibition profile, mostly targeting AGC group kinases. These inhibitors were the AKT inhibitors GSK-690693, AZD-5363, and AT-7867; the MSK inhibitor SB-747651-A; and the Rho kinases (ROCK) inhibitor GSK-269962A. Notably, the AGC and hippo kinases LATS1 and LATS2 were part of this subcluster and were both inhibited to significant extents by these 5 compounds. With the regenerative potential of a candidate LATS1/2 inhibitor in mind, we next developed several orthogonal biochemical and cellular assays to prioritize compounds that possessed the desired activity against LATS1/2 without the burden of cytotoxic “off-targets,” such as those resulting from strong AKT inhibition. Based on the results of these assays, we prioritized one of the initially identified kinase inhibitors as the starting point for an ongoing, rational structure-activity relationship (SAR) effort to develop novel, 1st-in-class, highly selective LATS1 and LATS2 inhibitors. We will present data showing how such novel LATS1/2 inhibitors efficiently block LATS1/2-dependent YAP phosphorylation, induce YAP nuclear translocation in a high cell-density setting, and promote the transcription of bona fide YAP target genes such as AMOTL2, CTGF, and CYR61. Finally, consistently with the activation of a YAP-dependent transcriptional program, small-molecule inhibitors of LATS1/2 kinases promoted proliferation/regeneration in an in vitro wound-healing assay. Altogether, we identified novel small molecules that can be used as chemical probes to acutely inactivate the Hippo signaling pathway and validated LATS1 and LATS2 kinases as novel druggable kinases whose inhibition could be exploited for several indications, spanning from regenerative medicine to cancer immunotherapy. Citation Format: Michele Ceribelli, Patrick Morris, Damien Duveau, Frances A. Tosto, Scott Hoyt, Craig J. Thomas. Development of selective LATS1/LATS2 inhibitors for the pharmacologic modulation of the Hippo signaling pathway [abstract]. In: Proceedings of the AACR Special Conference on the Hippo Pathway: Signaling, Cancer, and Beyond; 2019 May 8-11; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(8_Suppl):Abstract nr B06.