Figure 1.
Intratumoral 3M‐052 delivery slows primary tumor growth and prolongs survival in immunologically cold tumors. (a) C57BL6/J mice were injected with 1 × 105 E0771 cells into the 4th mammary fat pad, and palpable tumors were i.t. injected with vehicle or 3M‐052 on day 13 post‐inoculation and monitored for size. (b) BALB/c mice were injected with 1 × 105 4T1.2 cells into the 4th mammary fat pad, and palpable tumors were i.t. injected with vehicle or 3M‐052 on day 5 post‐inoculation and primary tumors were measured for size. Primary tumors from a separate group of mice resected on day 12 post‐inoculation were either (c) fixed and stained by IHC, with representative images for Ki67, c‐caspase‐3 and PD1 shown (10× magnification except H&E 4× magnification, scale bars = 100 µm, representative images shown); or (d) analysed by flow cytometry for primary tumor cellularity. (e) A proportion of lungs were taken on day 21 for H&E staining to assess metastatic burden; tumor regions are denoted by dotted line and ‘T’ (4× and 20× magnification, scale bars = 200 µm, representative images shown). (f) At endpoint, relative lung tumor burden (RTB) was assessed by RT‐qPCR on day 21. (g) A proportion of mice were assessed for metastasis‐free survival (Kaplan–Meier). MΦ: macrophage. Metastasis assay: n = 8–10 mice/group. Survival experiments: n = 10 mice/group; IHC: n = 3 mice/group; and flow cytometry: n = 7 mice/group. Experiments were independently repeated at least twice, and representative data are shown. Statistical analysis was performed by (a, b) one‐way RM ANOVA with post hoc Bonferroni's multiple comparison test; (d, f) the Student's two‐tailed t‐test; and (g) the Mantel–Cox log‐rank test. Error bars are SEM. *P < 0.05; **P < 0.01; and ****P < 0.0001.