Targeting TREX1 awakes systemic antitumor immunity. (A–D) C57BL/6J mice were transplanted s.c. with 2 × 10⁶ MC38 on the right flank on day 0 and with 2 × 10⁶ MC38, MC38-Trex1^−/−, MC38-Cgas^−/−, and MC38-Trex1^−/−Cgas^−/− cells on the left flank on day 3. Flowchart of bilateral tumors (A). Tumor growth of right tumors (B) and left tumors (C) was presented (n = 4–6). (D) Survival of tumor-bearing mice (n = 12). (E) C57BL/6 mice (n = 5 or 6) were transplanted s.c. with 2 × 10⁶ MC38 or MC38 with different ratios MC38-Trex1^−/− cells. Tumor growth of tumors was presented. (F–H) C57BL/6 mice (n = 3 or 4) were transplanted s.c. with 1 × 10⁷ MC38 or MC38 with different ratios MC38-Trex1^−/− cells. 12 days later, tumor tissues were collected and analyzed by flow cytometry. The percentage of CD8⁺ T cell (F) and CD69⁺CD8⁺ T cell in CD45⁺CD3⁺ cells (G) and PD1⁺TIM3⁺ CD8⁺ T cell (H) in CD8⁺ cells is shown. (I) BALB/c mice (n = 6) were transplanted s.c. with 5 × 10⁵ 4T1, 4T1-Mlh1^−/− (day 48) cells; tumors were treated i.t. with or without TREX1 inhibitor (TREX1-IN-1, HY-160785, MCE) treatment (120 μg/tumor) on day 7, 8, 9, and 10. (J) C57BL/6 mice (n = 7–10) were transplanted s.c. with 2 × 10⁶ MC38; tumors were treated i.t. with or without TREX1 inhibitor (TREX1-IN-1, HY-160785, MCE) treatment (120 μg/tumor) on day 7, 8, 9, and 10. (K) The working model of this study. Data indicate mean ± SEM and are representative of two (A–J) independent experiments. The statistical analysis was performed by two-way ANOVA in B–E, I, and J and unpaired Student’s two-tailed t test in F–H. NS, not significant, *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001.