Targeting the PI5P4K Lipid Kinase Family in Cancer Using Covalent Inhibitors

The PI5P4Ks have been demonstrated to be important for cancer cell proliferation and other diseases. However, the therapeutic potential of targeting these kinases is understudied due to a lack of potent, specific small molecules available. Here, we present the discovery and characterization of a pan-PI5P4K inhibitor, THZ-P1-2, that covalently targets cysteines on a disordered loop in PI5P4Kα/β/γ. THZ-P1-2 demonstrates cellular on-target engagement with limited off-targets across the kinome. AML/ALL cell lines were sensitive to THZ-P1-2, consistent with PI5P4K's reported role in leukemogenesis. THZ-P1-2 causes autophagosome clearance defects and upregulation in TFEB nuclear localization and target genes, disrupting autophagy in a covalent-dependent manner and phenocopying the effects of PI5P4K genetic deletion. Our studies demonstrate that PI5P4Ks are tractable targets, with THZ-P1-2 as a useful tool to further interrogate the therapeutic potential of PI5P4K inhibition and inform drug discovery campaigns for these lipid kinases in cancer metabolism and other autophagy-dependent disorders. [Display omitted] •Inhibitor THZ-P1-2 shows PI5P4K enzyme inhibition and target engagement in cells•THZ-P1-2 covalently targets unannotated cysteines outside the PI5P4K active site•AML/ALL cell lines are broadly sensitive to THZ-P1-2's covalent effects•PI5P4K inhibition causes autophagy disruption and upregulates TFEB signaling PI5P4K, an understudied kinase family, is essential in various disease contexts. Sivakumaren et al. develop and characterize PI5P4K inhibitor THZ-P1-2, which targets unique cysteines, exhibits effects in biochemical and cellular assays, displays anticancer activity in leukemia cell lines, and causes defects in autophagy similar to PI5P4K gene knockdown or deletion.