To confirm and quantify the infiltration of subcutaneous MC38 syngeneic colon cancer tumors with CXCR3-expressing T cells both at baseline and after ICI therapy (α-PD-1/α-CTLA-4 combination treatment) in a sufficient number for imaging, the following cohorts were investigated using imunohistochemistry (IHC) and immunofluorescence (IF) methods: [1] an untreated control group [2], a treated group receiving one cycle of ICI therapy and [3] a treated group receiving two cycles of ICI therapy at days 7 and 10 post tumor inoculation, respectively. The gene discussed is PDCD1; the disease is colonic neoplasm.