PDCD1 and neoplasm: In addition, kidney cancer (clear cell renal cell carcinoma, ccRCC) express multiple hERVs. Cancer ERV expression, confirmed through ribosome profiling combined with validation for MHC binding and identification of ERV epitope-specific T cells, correlated with anti-PD-1 immunotherapy response in ccRCC [170], which is remarkably high in this cancer despite its relatively low tumor mutation burden (TMB) [22].