Proteogenomic identification of an immunogenic antigen derived from human endogenous retrovirus in renal cell carcinoma

CD8(+) T cells can recognize tumor antigens displayed by HLA class I molecules and eliminate tumor cells. Despite their low tumor mutation burden, immune checkpoint blockade (ICB) is often beneficial in patients with renal cell carcinoma (RCC). Here, using a proteogenomic approach, we directly and comprehensively explored the HLA class I–presenting peptidome of RCC tissues and demonstrated that the immunopeptidomes contain a small subset of peptides derived from human endogenous retroviruses (hERV). A comparison between tumor and normal kidney tissues revealed tumor-associated hERV antigens, one of which was immunogenic and recognized by host tumor-infiltrating lymphocytes (TIL). Stimulation with the hERV antigen induced reactive CD8(+) T cells in healthy donor–derived (HD-derived) peripheral blood mononuclear cells (PBMC). These results highlight the presence of antitumor CD8(+) T cell surveillance against hERV3895 antigens, suggesting their clinical applications in patients with RCC.