Interestingly, clear cell Renal Cell Carcinoma (ccRCC) demonstrates overexpression of a retroviral antigen derived from a member of the HERV-E family (CT-RCC HERV-E or ERVE-4), compared to healthy tissues, which can be identified by antigen-specific CD8(+) T -cells, as has been reported in a patient who experienced regression of metastatic ccRCC after allogeneic hematopoietic stem cell transplantation (221). This evidence concerns the gene CD8A and nonpapillary renal cell carcinoma.