The systemic antitumor response is T-cell mediated. BALB/C mice were implanted with 5 × 10⁶ A20 cells on both flanks. (A) Local (treated site) and systemic effect of the treatment in the context of CD4 and/or CD8 T-cell depletion. Mice were treated with IT injection of STINGa and SC injection of anti-GITR. Treatment was given on day 6, 8, and 10 after tumor implantation. Depleting antibodies for CD4 and/or CD8 T-cell depletion were given on day 4, 5, 6, 11, and 14. One experiment with 10 mice per group. Statistical significance of tumor growth was calculated using 2-way ANOVA. (B-D) Tumor-specific CD4 and CD8 T cells in the spleen. On day 6, 8, and 10, mice were treated with IT injection of STINGa and/or SC injection of anti-GITR. On day 17, spleens were harvested. INF-γ–producing cells were monitored after restimulation with tumor cells (A20) or unrelated tumor cells (4T1). (B) Raw data of representative samples. (C) Percentage of CD44⁺INF-γ⁺ cell among the CD8 T cells. Statistical significance was calculated using 1-way ANOVA. (D) Percentage of CD44⁺INF-γ⁺ cell among the CD4 T cells. Statistical significance was calculated using 1-way ANOVA. (E) Treated tumor were harvested at 2 and 4 hours after IT injection of STINGa or vehicle control. Graphs illustrate percentage of CD8 T cell, CD4 T cell, Tregs (CD4⁺FoxP3⁺), and CD4eff (CD4⁺FoxP3⁻). Statistical significance was calculated using 1-way ANOVA. Error bars are SEM. *P < .05; **P < .01; ***P < .001.