Figure 5. PET imaging of ⁶⁸Ga-grazytracer in mouse models with or without inhibition of immune cell infiltration.

(A) Timeline of PET imaging, anti–PD-1 plus anti–CTLA-4 combinational immunotherapy, and FTY720 treatment in MC38 tumor–bearing mice. (B) Tumor growth curves of MC38 tumor–bearing mice after the indicated treatments: control (PBS), FTY720, anti–PD-1 plus anti–CTLA-4, and anti–PD-1 plus anti–CTLA-4 plus FTY720 (n = 6–9/group). (C and D) Representative PET images (C) and quantified tumor uptake (D) of ¹⁸F-FDG on days 0 and 6 in anti–PD-1– plus anti–CTLA-4–treated MC38 tumor–bearing mice with or without FTY720 treatment (n = 8–9/group). (E and F) Representative PET images (E) and quantified tumor uptake (F) of ⁶⁸Ga-grazytracer on days 0 and 6 in anti–PD-1– plus anti–CTLA-4–treated MC38 tumor–bearing mice with or without FTY720 treatment (n = 8–9/group). (G) Flow cytometric analysis depicting the proportion of NK1.1⁺ cells, CD4⁺ T cells, and CD8⁺ T cells in CD45⁺ cells in tumors harvested from mice after the indicated treatments (n = 5/group). Tumors are indicated by white arrows in PET images. All numerical data are presented as mean ± SD. *P < 0.05, **P < 0.01, ****P < 0.0001 by 2-way ANOVA (B), 2-tailed paired Student’s t test (D and F), and 2-tailed unpaired Student’s t test (G).