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. 2019 Feb 11;129(3):1278–1294. doi: 10.1172/JCI97642

Figure 1. Murine fibrosarcoma CMS5a is highly refractory to checkpoint inhibition and lacks a specific CD8+ T cell response.

Figure 1

(A) The murine tumor cell line CT26, CMS7, CMS5a/NY, or CMS5a was subcutaneously inoculated into BALB/c mice. Checkpoint inhibitors including anti–PD-1 (200 μg/mouse), anti–CTLA-4 (100 μg/mouse), and anti-GITR (200 μg/mouse) Abs (n = 8–10 mice per group) or isotype control Abs (n = 8 mice per group) were i.p. injected on days 7, 9, and 11. (B) The experiment was performed in nude mice as described in A. (C and D) Induction of a tumor-specific CD8+ T cell response by checkpoint inhibition was evaluated. BALB/c mice bearing CT26, CMS7, CMS5a/NY, or CMS5a tumors were treated with checkpoint inhibitors. Seven days after the last administration, splenocytes were isolated and restimulated with peptides of predicted neoepitopes or known tumor antigens (AH-1 in CT26 and NY-ESO-1 p81 in CMS5a/NY tumors). The frequency of stimulated CD8+ T cells was quantified by (C) intracellular IFN-γ staining (n = 4 mice per group) or (D) the fold increase in CXCL9 mRNA levels compared with DMSO. The experiments were repeated at least 2 to 4 times with similar results. *P < 0.05, by Mann-Whitney U test.