PDCD1 and nonpapillary renal cell carcinoma: To model immune checkpoint inhibition therapy of human ccRCC we used an autochthonous mouse model of ccRCC based on tamoxifen-induced gene deletion in Ksp1.3-CreERT2; Vhlfl/fl; Trp53fl/fl, Rb1fl/fl mice19 (hereafter abbreviated as VpR) to test the effects of treatment with isotype control antibodies (hereafter ICI ctrl) or combined anti-PD-1 plus anti-CTLA-4 antibodies (immune checkpoint inhibition, hereafter ICI) (Fig. 1a).