Fig. 1: Discovery of a novel potent STING agonist HB3089.

a Chemical structure of HB3089. b, c The thermal stability of human STING (R232) and mouse STING (R231) bound with HB3089 or diABZI (compound 3) in DSF assay. The data were shown as the mean values of d(RFU)/dt, n = 3. d HB3089 dose-dependently activated the ISG reporter in THP1-Dual cells after 24 h treatment. e The activation of ISG reporter by HB3089 (1 μM) was abolished in THP1-Dual-KO-STING cells after 24 h treatment. f HB3089 activated ISG reporter in RAW-Lucia cells after 24 h treatment. g The activation of ISG reporter by HB3089 (50 μM) was abolished in RAW-Lucia KO-STING cells after 24 h treatment. h Anti-tumor effect of HB3089 and diABZI (compound 3) in 4T1 breast tumor of Balb/c mice by intravenous (IV) administration on days 1, 4, 7, n = 6. i Anti-tumor effect of HB3089 in EMT6 breast tumor of Balb/c mice by IV administration, n = 6. Arrows indicate the days (1, 4, 7) of administration. ^**P < 0.01, ^****P < 0.0001, Two-way ANOVA. j EMT6 tumor growth in naïve mice and rechallenged mice, the number of EMT6 tumor-bearing mice and total mice were shown, respectively. k–n Frequency of CD86⁺DC, CD86⁺macrophages, GMZB⁺CD8T cells and IFNγ⁺CD8T cells in blood (24 h) and tumor tissues (24 h and 72 h) of 4T1 tumor-bearing Balb/c mice, n = 8. HB3089 was administrated by IV at 2 mg/kg. ns, not significant; ^*P < 0.05, ^***P < 0.001^, two-tailed Student’s t-test.