Comprehensive tumor-immune profiling reveals mediators of paradoxical immune sensitivity in sarcomatoid renal cell carcinoma.

Renal cell carcinoma with sarcomatoid features (sRCC) is a highly aggressive tumor type yet preferentially responds to immune checkpoint blockade (ICB). To better understand microenvironmental mediators of this paradoxical immune sensitivity, we performed single-cell analyses of human sRCC tumors compared against clear cell RCC (ccRCC), with validation spatially and in bulk transcriptomic datasets totaling over 3,000 RCC tumors. We describe a robust immune network in sRCC using these orthogonal approaches: tumor-infiltrating T cells in sRCC are more activated, and subsequently exhausted, while being enriched for CXCL13 expression.