Stereoselective Degradation of Diacylglycerol Kinases Potentiate T cell Activation and Tumor Cell Cytotoxicity

ABSTRACT Stereoselective recognition is a powerful means to differentiate selective versus non-specific activity of small molecules in complex biological systems. Here, we disclose stereochemically defined, sulfonyl-triazole inhibitors of the lipid enzyme diacylglycerol kinase-alpha (DGKα), a key metabolic checkpoint for T cell effector function. Acute treatment with the covalent DGKα inhibitor AHL-7160 recruited endogenous DGKα to the plasma membrane in a stereoselective and isozyme-specific manner. The membrane translocation activity of AHL-7160 correlated with blockade of cellular phosphatidic acid production and potentiation of primary T cell-mediated killing of a glioblastoma cell line. Quantitative chemoproteomics revealed Y669 and K411 as sites of AHL-7160 modification on endogenous DGKα in cells. Extended treatments resulted in proteasome-dependent and proteome-wide selective degradation of DGKα in T cells. Collectively, these findings establish covalent DGKα ligands as potent molecular glues with translational potential in immunotherapy. Competing Interest Statement K.-L.H. is a founder and scientific advisory board member of Hyku Biosciences. A patent application has been filed on the work presented in this manuscript.