VSIR and malignant colon neoplasm: Strikingly, when B7-H3–CAR-T cells were injected into NCG mice bearing s.c. patient-derived xenograft (PDX) tumors of colon cancer, PD-1H expression was upregulated in human T cells that had infiltrated the spleen and tumor tissues, whereas PD-1H expression in T cells from blood remained low (Figure 6, B and C).