Fig. 8: CD47 blockade enhances T-DXd anti-tumor efficacy in vivo.
a Tumor-bearing (>500 mm3) HER2-transgenic mice were treated weekly for the first four weeks with control IgG1 antibody (rituximab 10 mg/kg), T-DXd (5.4 mg/kg), anti-CD47 (see Methods) or in combination. Animal survival is plotted. Log-rank (Mantel-Cox) test between T-DXd monotherapy versus combination therapy (n = 15 per group). b Anti-tumor humoral responses in serum from mice in (a) were assessed by ELISA quantification of mouse IgG against HER2. Two-way ANOVA with Tukey’s multiple comparisons (n = 15). c–f Intratumor macrophages (live CD45+/CD11b+/Gr1−/F/480+) analysis after 1 week of treatment with control IgG1 (n = 8), T-DXd (n = 7) or T-DXd plus anti-CD47 (n = 6). c Macrophage percentage, (d) phagocytosis of GFP+ tumor cells, (e) CD40 expression and (f) MHC-II expression were assessed by flow cytometry. g–j Tumor-infiltrating CD8+ T cells (live CD45+/CD11b-/CD8+) analysis after 4 weeks of treatment with control IgG1 (n = 8), T-DXd (n = 12) or T-DXd plus anti-CD47 (n = 6). g Percentage of infiltrated CD8+ T cells. h CD107a cytotoxic marker expression. i naive CD8 T cells (CD62L+/CD44−). j Activated effector CD8 T cells (CD62L−/CD44+). k Immunohistochemistry assessment of tumor-infiltrating T cells levels and spatial location. CD8+ (brown), CD4+ (blue) and FoxP3+ (red), intratumor T cells (black arrows), T cells in stroma (green arrows) are shown for representative sections for each group. l Ratio of quantified CD8+ counts in tumor bed versus stroma in (k) (n = 5 per group). c–l One-way ANOVA with Tukey’s multiple comparisons test. m HER2-transgenic mice with moderate tumor sizes (>150 mm3) were treated weekly with T-DXd (10 mg/kg) and anti-CD47. Complete tumor regressors were randomly assigned to CD8 depletion group or control depletion group. T-DXd and anti-CD47 treatments were halted, and mouse CD8 depletion antibodies (10 mg/kg) or PBS control were administered weekly. Tumor regression after combination therapy and relapse after CD8 depletion were monitored over time. Each line represents tumor growth from one animal subject. n Percentage of tumor-free animals in control versus CD8 depleted groups in (m). Log-rank (Mantel-Cox) test (n = 12). All data is presented as mean ± SEM with p values indicated.
