A STING inhibitor; binds to Cys91 on STING to block its and prevents recruitment and phosphorylation of TBK1 in HEK293T cells; selectively reduces STING-, but not RIG-I- or TBK1-, mediated IFN-β reporter activity in HEK293 cells from 0.01-1.25 μM; prevents increases in Ifnb1 expression induced by cyclic di-GMP, double-stranded DNA, and LPS in BMDMs at 0.5 μM