– CAY10748 is an agonist of stimulator of interferon genes (STING; IC50= 0.3794 μM in a competition binding assay).1It activates STING in STING-expressing, but not STING knockout, THP-1 cells (EC50s = 0.287 and >100 μM, respectively, in a reporter assay). It induces phosphorylation of STING at the serine in position 366, as well as phosphorylation of TBK1 and IFN regulatory factor 3 (IRF3), indicating activation of the STING-TBK1-IRF3 signaling pathway. CAY10748 increases the secretion of IFN-β and the levels of chemokine (C-X-C motif) ligand 10 (CXCL10), and IL-6 in peripheral blood mononuclear cells (PBMCs) when used at a concentration of 10 μM. It also reduces tumor growth in a CT26 murine colon cancer model when administered at a dose of 0.15, but not 1.5, mg/kg.