Single cell sequencing of anti-PD-1 treated xenograft from mice bladder urothelium with Trp53, Rb1, PTEN mutations on C57 BL/6J

To determine the immune mechanism of anti-PD1 therapy, we carried out an anti-PD1 treatment on C57 BL/6J mice bearing mouse bladder urothelial carcinoma with three gene knockout. Anti-PD-1 immunotherapy resulted in a mixed pattern of treatment responses in individual tumors. Then, we performed single cell transcriptome profiling for tumor xenografts from Control IgG, anti-PD-1 non-responders and anti-PD-1 responders group. Duplicate tumors in each group were mixed and sequenced together as one representative sample. In results, we captured 4762 cells from Control IgG group, 4459 cells from anti-PD-1 non-responders group and 4861 cells from anti-PD-1 responders group. identified 8 clusters of immune cells in treated samples (basophils, B cells, dendritic cells, macrophages, monocytes, neutrophils, NK cells, and T cells). Responder xenografts displayed significantly increased immune cell infiltration (15.2%, 742 immune cells / 4861 total cells) compared to the non-responder tumors (10.1%, 452 immune cells/ 4459 total cells, Fisher Exact Test p<0.0001). Specifically, there were more T cells (46/4861 vs 18 /4459, p=0.002), and macrophages (420/4861 vs 287/4459, p=0.002) in responder xenografts than in non-responder xenografts. Compared to control IgG tumors, response tumors exhibited an immune-inflamed phenotype with significant infiltration of T cells and NKT cells, whereas non-responder tumors showed no significant change. The higher percentage of T cells and macrophages tumor infiltration in responders suggests a potential role of innate immune microenvironment for the Immune checkpoint inhibitor (ICI) treatment response. This study provides the insights of immune environments in ICI-treated bladder tumor xenograft on C57 mice. Overall design: Single cell transcriptome profiling of control IgG or anti-PD-1 treated xenograft on C57 BL/6J