Discovery of (4-Phenyl-cyclohexyl)acetate-Derived Tyrosylprotein Sulfotransferase 2 (TPST2) Inhibitors with Potent Anti-Tumor Activity for Immuno-Oncology Applications

Tyrosylprotein sulfotransferase 2 (TPST2) was recently reported to mediate the post-translational sulfation of interferon γ (IFNγ) receptor, contributing to immunosuppression in tumor microenvironment. Herein, we report the discovery of <b>77c</b> with an IC₅₀ value of 946 nM as a novel TPST2 inhibitor through the structure-activity relationship (SAR) studies and optimization of a hit compound, <b>44a</b>, identified in the enzyme-based screening of 6868 compounds from Korea Chemical Bank (KCB) library. <b>77c</b> was further evaluated for its binding affinity at TPST2 and effects in IFNγ signaling in cell-based functional assays. <i>In silico</i> docking analysis suggested the putative binding site of <b>77c</b> and key molecular interactions, providing structural insights into TPST2 inhibition. Furthermore, in the MC38 syngeneic tumor model, <b>77c</b> significantly suppressed tumor growth and synergized with anti-PD-1 therapy, leading to enhanced T cell-mediated antitumor immunity characterized by increased infiltration of effector CD8⁺ T cells and improved systemic immune activation.