Figure 7 from Trabectedin Enhances the Antitumor Effects of IL-12 in Triple-Negative Breast Cancer

Anti–PD-L1 therapy improves response to combination IL-12 and trabectedin treatment. Mice bearing ∼50 mm³ 4T1 tumors were treated with 0.5 μg IL-12 i.p. 3×/week and 0.15 mg/kg trabectedin i.v. 1×/week for 7 days with either αPD-L1 therapy (100 μg 3×/week, n = 5) or isotype control IgG (100 μg 3×/week, n = 6). A, Tumor growth curves throughout treatment. B, Tumor images after excision. One mouse from the triple combination group had a complete response and therefore had no tumor for imaging. For statistical analyses of tumor volumes, linear mixed modeling was used to model longitudinal tumor volume for mice under each treatment. Comparisons were done at each time point and averaged across all time points using t-statistics. The Tukey–Kramer method was used for adjusting raw P values for multiple comparisons across treatment groups. C, Individual tumor growth curves of mice treated with PBS + αPD-L1, IL-12 and trabectedin + IgG, and IL-12 and trabectedin + αPD-L1. D, Plasma levels of IFN-γ in mice treated with IL-12 and trabectedin + IgG or αPD-L1 at day 15 (n = 3–5). Statistical analysis was performed using two-tailed unpaired student t tests. E–I, Percentages of splenic immune cells at day 15. An ordinary one-way ANOVA with the Tukey multiple comparisons test was used for statistical analyses of mass cytometry data. Data represent mean ± SEM. J, Proposed mechanism of IL-12 and trabectedin–induced antitumor immunity. Trabectedin reduced inhibitory immune cells (MDSC and TAMs) in mice bearing TNBC tumors. Without the presence of a highly immunosuppressive TME, trabectedin and/or IL-12 may be able to activate NK cells and lead to increased CCL5 and XCL1 production. CCL5 and XCL1 can attract CXCL10-producing cDC1 into the TME, where these cells can cross-present antigen to CD8⁺ T cells and promote an improved antitumor response. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001. TCR, T-cell receptor; Trab, trabectedin.